ORCID Profile
0000-0001-5679-2404
Current Organisations
CSIRO
,
CSIRO Armidale
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Publisher: Public Library of Science (PLoS)
Date: 03-03-2009
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.PARINT.2022.102539
Abstract: Haemonchus contortus is the most prevalent and pathogenic gastrointestinal nematode infecting sheep and goats. The two CSIRO sheep resource flocks, the Haemonchus-selected flock (HSF) and Trichostrongylus-selected flock (TSF) were developed for research on host resistance or susceptibility to gastrointestinal nematode infection. A recent study focused on the gene expression differences between resistant and susceptible sheep within each flock, with lymphatic and gastrointestinal tissues. To identify features in the host transcriptome and understand the molecular differences underlying host resistance to H. contortus between flocks with different selective breeding and genetic backgrounds, we compared the abomasal transcriptomic responses of the resistant or susceptible animals between HSF and TSF flocks. A total of 11 and 903 differentially expressed genes were identified in the innate infection treatment in HSF and TSF flocks between resistant and susceptible sheep respectively, while 52 and 485 genes were identified to be differentially expressed in the acquired infection treatment, respectively. Among them, 294 genes had significantly different gene expression levels between HSF and TSF flock animals within the susceptible sheep by both the innate and acquired infections. Moreover, similar expression patterns of the 294 genes were observed, with 273 genes more highly expressed in HSF and 21 more highly expressed in the TSF within the abomasal transcriptome of the susceptible animals. Gene ontology enrichment of the differentially expressed genes identified in this study predicted the likely differing function between the two flock's susceptible lines in response to H. contortus infection. Nineteen pathways were significantly enriched in both the innate and adaptive immune responses in susceptible animals, which indicated that these pathways likely contribute to the host resistance development to H. contortus infection in susceptible sheep. Biological networks built for the set of genes differentially abundant in susceptible animals identified hub genes of PRKG1, PRKACB, PRKACA, and ITGB1 for the innate immune response, and CALM2, MYL1, COL1A1, ITGB1 and ITGB3 for the adaptive immune response, respectively. Our results offered a quantitative snapshot of host transcriptomic changes induced by H. contortus infection between flocks with different selective breeding and genetic backgrounds and provided novel insights into molecular mechanisms of host resistance.
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.TVJL.2013.03.029
Abstract: Modern livestock breeding practices provide new opportunities for producing animals that are adapted to their production environment and are free of disease. Using current knowledge of biology and by seeking 'the desired outcome' animal selection strategies can be designed that deliver more precisely defined results so maximising genetic gain and minimising risk. This review briefly describes the evolution of genetic selection in livestock and considers some of the positive and negative aspects of selection practices over time. The selection of sheep to withstand gastro-intestinal nematode parasitism is used as an ex le to explain how developments in selection strategy have improved genetic progress for complex traits. Re-evaluation of the understanding of the outcomes of selection for parasite resistance is used here to examine whether a more sophisticated approach is desirable, and to propose a number of additional phenotype measurement strategies that could complement and improve the quality of information used for animal selection. Finally some ideas are presented for creating a situation where a designed, highly defined breeding objective might be used to increase precision and reduce risk. This may become possible via research to adapt or develop tools for more sophisticated phenotypic evaluation, to discover biological processes integral to desired breed changes, and to define desired animal types which match economic and societal expectations.
Publisher: Elsevier BV
Date: 2019
DOI: 10.3382/PS/PEY383
Abstract: Ascaridia galli is one of the most abundant nematode parasites in poultry. A. galli infections can significantly impact the profitability of egg farms and have negative implications for bird health and welfare. The main objectives of this study were to determine whether A. galli specific antibodies in egg yolks can be used to detect prior or current exposure to A. galli in laying hens, and to distinguish between eggs obtained from caged and free-range hens. Twenty-two laying hen flocks from different production systems (10 free-range, 2 barn-housed, and 9 caged flocks) were enrolled in the study. An in-house enzyme-linked immunosorbent assay was used to analyze levels of A. galli specific antibodies in yolk. The numbers of A. galli eggs in hen excreta were also determined in a subset of farms. Free-range flocks had higher and also more variable levels of anti-A. galli antibodies in the egg yolk compared to those of the cage flocks (0.50 ± 0.39 vs. 0.16 ± 0.13 OD units) (P < 0.001). Results also confirmed that excreta from free-range and barn-housed flocks contained higher numbers of A. galli eggs than did excreta from caged flocks in which no A. galli eggs were detected. In conclusion, analysis of anti-A. galli antibodies in the egg yolk can be used to detect worm exposure in commercial layer flocks. However, the method used in this study cannot be used in isolation to distinguish between eggs from cage and free-range production systems as anti-A galli antibodies were detected in egg yolk s les from all production systems, and the range of antibody levels overlapped between production systems.
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.VETIMM.2019.04.006
Abstract: The primary function of the mammary gland is to produce milk to feed the suckling young. In ruminants, ingestion of maternal antibodies in mammary secretions facilitates the transfer of passive immunity from mother to young, providing antibody-mediated immunity to protect the neonate against disease while their own immune system develops. Antibodies in mammary secretions also play a role in protecting the gland itself against infection. Here we provide a brief history of studies on immunoglobulins in ruminant mammary secretions and review recent findings describing the mechanisms by which antibody-producing plasmablasts are recruited to the gland and immunoglobulins are transported into ruminant mammary secretions. An improved understanding of the complex interaction of factors which regulate immunoglobulin production and transfer to the ruminant mammary gland may provide opportunities to enhance antibody concentrations in mammary secretions during normal lactation and in response to immunisation. Strategies aimed at increasing antibody concentrations in ruminant mammary secretions have the potential to improve the ability of animals to resist mammary infections, enhance the transfer of passive immunity from mother to young and increase the feasibility of harvesting antibodies from the mammary secretions for use in commercial therapeutic applications for humans and domesticated animals.
Publisher: Elsevier BV
Date: 04-1999
Publisher: Proceedings of the National Academy of Sciences
Date: 28-08-2001
Abstract: We have identified a nuclear-encoded Hb from plants (GLB3) that has a central domain similar to the “truncated” Hbs of bacteria, protozoa, and algae. The three-dimensional structure of these Hbs is a 2-on-2 arrangement of α-helices, distinct from the 3-on-3 arrangement of the standard globin fold [Pesce, A., Couture, M., Dewilde, S., Guertin, M., Yamauchi, K., Ascenzi, P., Moens, L. & Bolognesi, M. (2000) EMBO J. 19, 2424–2434]. GLB3- like genes are not found in animals or yeast, but our analysis reveals that they are present in a wide range of Angiosperms and a Bryophyte. Although cyanobacteria and Chlamydomonas have 2-on-2 Hbs (GLBN), GLB3 is more likely related to GLBO-type 2-on-2 Hbs from bacteria. Consequently, GLB3 is unlikely to have arisen from a horizontal transfer between the chloroplast and nuclear genomes. Arabidopsis thaliana GLB3 protein exhibits unusual concentration-independent binding of O 2 and CO. The absorbance spectrum of deoxy-GLB3 is unique the protein forms a transient six-coordinate structure after reduction and deoxygenation, which slowly converts to a five-coordinate structure. In A. thaliana , GLB3 is expressed throughout the plant but responds to none of the treatments that induce plant 3-on-3 Hbs. Our analysis of the sequence, ligand interactions, and expression profile of GLB3 indicates that this protein has unique biochemical properties, evolutionary history, and, most likely, a function distinct from those of other plant Hbs.
Publisher: Cambridge University Press (CUP)
Date: 14-04-2010
DOI: 10.1017/S003118201000020X
Abstract: This study aimed to identify putative quantitative trait loci (QTL) that significantly affect internal parasite resistance in a backcross sheep population. A Romney×Merino backcross (to Merino) flock was challenged in 3 separate infections with Trichostrongylus colubriformis (primary and secondary) and Haemonchus contortus (tertiary). Haematological parameters were measured and faecal worm egg counts (FWEC) were established to estimate parasite burden. QTL mapping was conducted for FWEC and for the changes in haematocrit following H. contortus challenge and in eosinophil numbers following T. colubriformis challenge. Animals were genotyped for 55 microsatellite markers on selected chromosomes 2, 3, 6, 11, 13, 15, 21, and 22. Four putative quantitative trait loci were found these being for eosinophil change in the primary infection (OAR 21), for FWEC in the first infection and eosinophil change in the secondary infection (OAR 3) and for FWEC in the secondary infection (OAR 22). No significant quantitative trait loci were detected for FWEC or haematocrit change during the Haemonchus contortus infection. The position of the putative quantitative trait loci for eosinophil change on OAR 3 is consistent with other reports of parasite resistance quantitative trait loci, implying some commonality between studies.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.3382/PS/PEY068
Abstract: A study was conducted to determine the performance, egg quality, and liver lipid reserves of laying hens exposed to ranges contaminated with Ascaridia galli. Sixteen-week-old Lohmann Brown laying hens (n = 200) were ided into 4 treatments with 5 replicates containing 10 hens per pen. Hens of treatment 1 [negative control (NC)] ranged on a decontaminated area, and hens of treatments 2 (low infection) and 3 (medium infection) ranged on areas previously contaminated by hens artificially infected with 250 and 1,000 embryonated A. galli eggs, respectively. The hens of treatment 4 [positive control (PC)] ranged on areas previously contaminated by hens artificially infected with 2,500 embryonated A. galli eggs, and in addition these hens were orally inoculated with 1,000 embryonated eggs. Results indicated that hens of the medium infection group had a higher number of intestinal A. galli worms and A. galli eggs in the coprodeum excreta (43.9 ± 4.0 and 3,437 ± 459 eggs/g) compared to hens of the low infection group (23.8 ± 4.0 and 1,820 ± 450 eggs/g) (P 0.05). Egg production, egg mass, feed intake, and feed conversion ratio (FCR) were not affected by A. galli infection (P > 0.05). Egg quality parameters (egg weight, shell reflectivity, shell weight, shell thickness, shell percentage, shell breaking strength, deformation, albumen height, Haugh unit, and yolk score) were not affected by A. galli infection (P > 0.05). Highly infected hens had lower liver lipid content (2.72 ± 0.51 g) compared to uninfected hens (4.46 ± 0.58 g, P < 0.01). The results indicate that exposure to ranges contaminated with A. galli resulted in infection of the ranging hens, but this did not affect egg production or egg quality. Infection with A. galli lowered the liver lipid reserves of the host significantly, suggesting infected hens use more energy reserves for maintenance and production.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.VETPAR.2011.11.055
Abstract: Traditional methods for the diagnosis of parasitic helminth infections of livestock have a number of limitations, such as the inability to distinguish mixed-species infections, a heavy reliance on technical experience and also sub-s ling errors. Some of these limitations may be overcome through the development of rapid and accurate DNA-based tests. For ex le, DNA-based tests can specifically detect in idual species in a mixed infection at either the larval or egg stages, in the absence of morphological differences among species. Even so, some diagnostic problems remain the same, irrespective of whether a DNA-based or traditional method is used. For ex le, sub-s ling errors from an aggregated distribution are likely to persist. It is proposed, however, that DNA-based diagnostic technologies offer an opportunity to expand diagnostic capabilities, and are discussed in the current review. The future introduction of DNA-based diagnostic technologies into routine diagnostic settings will also be discussed.
Publisher: American Meteorological Society
Date: 15-11-2004
DOI: 10.1175/3199.1
Abstract: The analysis of climatological data often involves statistical significance testing at many locations. While the field significance approach determines if a field as a whole is significant, a multiple testing procedure determines which particular tests are significant. Many such procedures are available, most of which control, for every test, the probability of detecting significance that does not really exist. The aim of this paper is to introduce the novel “false discovery rate” approach, which controls the false rejections in a more meaningful way. Specifically, it controls a priori the expected proportion of falsely rejected tests out of all rejected tests additionally, the test results are more easily interpretable. The paper also investigates the best way to apply a false discovery rate (FDR) approach to spatially correlated data, which are common in climatology. The most straightforward method for controlling the FDR makes an assumption of independence between tests, while other FDR-controlling methods make less stringent assumptions. In a simulation study involving data with correlation structure similar to that of a real climatological dataset, the simple FDR method does control the proportion of falsely rejected hypotheses despite the violation of assumptions, while a more complicated method involves more computation with little gain in detecting alternative hypotheses. A very general method that makes no assumptions controls the proportion of falsely rejected hypotheses but at the cost of detecting few alternative hypotheses. Despite its unrealistic assumption, based on the simulation results, the authors suggest the use of the straightforward FDR-controlling method and provide a simple modification that increases the power to detect alternative hypotheses.
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1016/J.IJPARA.2007.04.016
Abstract: Gastrointestinal nematode infections of livestock animals are prevalent and costly problems worldwide. Currently, infections are controlled by anthelmintic chemicals but increasing drug resistance has prompted research interest to shift towards alternative methods of control such as vaccine development and selection of worm-resistant animals. The present study analyses proteins from Trichostrongylus colubriformis infective L3s that are recognised by IgG of immune sheep. Following protein separation via two-dimensional electrophoresis and Western blot probing with plasma from sheep resistant to T. colubriformis, mass spectrometry-based proteomic analyses were used to identify immuno-reactive protein spots. We were able to identify 28 immune targets, including aspartyl protease inhibitor, enolase, chaperone proteins, galectin, glycolytic enzymes, kinase, phosphatase and structural muscle proteins such as myosin, paramyosin, calponin and DIM-1. The data suggest that immune responses to T. colubriformis are dispersed over a relatively large number of parasite antigens, including several cytoplasmically expressed proteins. The results have new implications for understanding the molecular mechanisms that underpin host-parasite interaction during gastrointestinal nematode infections.
Publisher: Informa UK Limited
Date: 12-12-2016
DOI: 10.1080/03079457.2016.1248898
Abstract: Infectious bursal disease virus (IBDV) is endemic to most poultry-producing countries worldwide. Immunosuppressive classical and variant IBDV strains endemic to Australia are genetically distinct from other international strains. We report the results of infection experiments with Australian classical strain 06/95 and variant strain 02/95 in SPF chickens. We tested the effects of strain and age of infection on bursal atrophy, viral RNA (vRNA) load in bursa of Fabricius (bursa), spleen, thymus, caecal tonsils, faeces, litter and exhaust dust as determined by real-time reverse transcriptase polymerase chain reaction. The two IBDV strains did not differ in the degree of bursal atrophy induced, lymphoid organ distribution and faecal shedding but variant strain 02/95 induced a greater antibody response to the infection than classical strain 06/95 which was associated with a more rapid decline in IBDV vRNA genome copy number (VCN) in lymphoid organs and faeces. Infection at 14 days of age induced greater bursal atrophy and higher vRNA copy number in lymphoid tissues than infection on the day of hatching, indicating true age susceptibility independent of maternal antibody (Mab) status. The direction of the association between rankings for IBDV vRNA load in bursa and relative bursal weight changed from positive at 3 and 6 days post-infection to negative at 28 days post-infection. Intra-tracheal administration of dust collected from chickens infected with IBDV resulted in successful transmission of IBDV. IBDV vRNA was detected successfully at high levels in the environmental litter and dust s les.
Publisher: Proceedings of the National Academy of Sciences
Date: 16-12-2002
Abstract: Overexpression of a class 1 Hb (GLB1) protects Arabidopsis thaliana plants from the effects of severe hypoxia. Overexpression of the bifunctional symbiotic Hb (GLB1S) from Parasponia andersonii in A. thaliana also increases survival after hypoxia. Plants overexpressing the Hb 1 protein, mutated to have a low oxygen affinity, are as susceptible to hypoxia as WT plants, suggesting that the protection against hypoxia depends on the ability of the Hb to bind ligands, such as oxygen, with high affinity. A mild hypoxia pretreatment (5%) induces the Hb gene and increases the survival of plants after severe hypoxic treatment (0.1%). These results with Hb 1 show that plant Hbs have a role other than in nitrogen-fixing root nodules. Plants overexpressing the GLB1 protein show early vigorous growth in nonhypoxic conditions and are 50% larger in weight than the controls at 14 days. The constitutive expression of GLB1 also resulted in a reduced number of root hairs and increased number of laterals in the root system.
Publisher: Springer Science and Business Media LLC
Date: 14-06-2009
DOI: 10.1007/S00438-009-0464-4
Abstract: Peach and almond have been considered as model species for the family Rosaceae and other woody plants. Consequently, mapping and characterisation of genes in these species has important implications. High-resolution melting (HRM) analysis is a recent development in the detection of SNPs and other markers, and proved to be an efficient and cost-effective approach. In this study, we aimed to map genes corresponding to known proteins in other species using the HRM approach. Prunus unigenes were searched and compared with known proteins in the public databases. We developed single-nucleotide polymorphism (SNP) markers, polymorphic in a mapping population produced from a cross between the cloned cultivars Nonpareil and Lauranne. A total of 12 SNP-anchored putative genes were genotyped in the population using HRM, and mapped to an existing linkage map. These genes were mapped on six linkage groups, and the predicted proteins were compared to putative orthologs in other species. Amongst those genes, four were abiotic stress-responsive genes, which can provide a starting point for construction of an abiotic resistance map. Two allergy and detoxification related genes, respectively, were also mapped and analysed. Most of the investigated genes had high similarities to sequences from closely related species such as apricot, apple and other eudicots, and these are putatively orthologous. In addition, it was shown that HRM can be an effective means of genotyping populations for the purpose of constructing a linkage map. Our work provides basic genomic information for the 12 genes, which can be used for further genetic and functional studies.
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.VETPAR.2011.05.027
Abstract: Since 1977, >2000 research papers described attempts to detect, identify and/or quantify parasites, or disease organisms carried by ecto-parasites, using DNA-based tests and 148 reviews of the topic were published. Despite this, only a few DNA-based tests for parasitic diseases are routinely available, and most of these are optional tests used occasionally in disease diagnosis. Malaria, trypanosomiasis, toxoplasmosis, leishmaniasis and cryptosporidiosis diagnosis may be assisted by DNA-based testing in some countries, but there are very few cases where the detection of veterinary parasites is assisted by DNA-based tests. The diagnoses of some bacterial (e.g. lyme disease) and viral diseases (e.g. tick borne encephalitis) which are transmitted by ecto-parasites more commonly use DNA-based tests, and research developing tests for these species makes up almost 20% of the literature. Other important uses of DNA-based tests are for epidemiological and risk assessment, quality control for food and water, forensic diagnosis and in parasite biology research. Some DNA-based tests for water-borne parasites, including Cryptosporidium and Giardia, are used in routine checks of water treatment, but forensic and food-testing applications have not been adopted in routine practice. Biological research, including epidemiological research, makes the widest use of DNA-based diagnostics, delivering enhanced understanding of parasites and guidelines for managing parasitic diseases. Despite the limited uptake of DNA-based tests to date, there is little doubt that they offer great potential to not only detect, identify and quantify parasites, but also to provide further information important for the implementation of parasite control strategies. For ex le, variant sequences within species of parasites and other organisms can be differentiated by tests in a manner similar to genetic testing in medicine or livestock breeding. If an association between DNA sequence and phenotype has been demonstrated, then qualities such as drug resistance, strain ergence, virulence, and origin of isolates could be inferred by DNA-based tests. No such tests are in clinical or commercial use in parasitology and few tests are available for other organisms. Why have DNA-based tests not had a bigger impact in veterinary and human medicine? To explore this question, technological, biological, economic and sociological factors must be considered. Additionally, a realistic expectation of research progress is needed. DNA-based tests could enhance parasite management in many ways, but patience, persistence and dedication will be needed to achieve this goal.
Publisher: Microbiology Society
Date: 11-2015
DOI: 10.1099/JGV.0.000268
Abstract: Infectious laryngotracheitis (ILT) is an important disease of chickens caused by ILT virus (ILTV). We used the Australian SA2 and A20 vaccine strains of ILTV to determine tissue distribution and excretion characteristics of ILTV in specific-pathogen-free chickens and to determine whether ILTV is readily detectable in environmental s les such as faeces, bedding material and dust using real-time quantitative PCR. Three groups of 10 freshly hatched chicks were placed in isolators and infected orally with high doses of the two strains of vaccine virus or left unchallenged as controls. Over a 28-day post-infection (p.i.) period, faecal and serum s les were collected at frequent intervals from six in idually identified chickens in each group. Dust and litter s les from the isolators were collected less frequently. Tissue s les were collected from three to four sacrificed or dead/euthanized birds at 6, 14 and 28 days p.i. Infection resulted in clinical ILT, a pronounced antibody response and sustained qPCR detection of the viral genome in the trachea, Harderian gland, lung and kidney up to 28 days p.i. A high level of the viral genome was also detected in faeces between 2 and 7 days p.i., declining by about approximately four orders of magnitude to low, but detectable, levels at 21 and 28 days p.i. The finding of high-level shedding of ILTV in faeces warrants further investigation into the epidemiological role of this, and the sustained high levels of ILTV observed in dust suggest that it may be a useful s le material for monitoring ILTV status in flocks.
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.JPROT.2012.01.016
Abstract: Sheep have a variable ability to resist gastrointestinal nematode infection, but the key factors mediating this response are poorly defined. Here we report the first large-scale application of quantitative proteomic technologies to define proteins that are differentially abundant between sheep selectively bred to have an enhanced (resistant) or reduced (susceptible) ability to eliminate nematodes. S les were collected from the abomasal mucosa three days after experimental challenge with the nematode, Haemonchus contortus. This timing reflects the initial interaction of host and parasite, and the tissue represents the immediate interface. We identified and quantified more than 4400 unique proteins, of which 158 proteins showed >1.5 fold difference between the resistant and susceptible sheep. Trefoil factor 2, a member of RAS oncogene family (RAP1A) and ring finger protein 126 were amongst the proteins found to be highly abundant in the abomasal surface of resistant sheep, whereas adenosine deaminase and the gastrokine-3 like precursor were found at higher levels in susceptible sheep. Construction of gut proteome interaction networks identified mitochondrial function and energetic partitioning as important components of an effective nematode eliminating response. The differentially abundant proteins may be useful targets for phenotypic tests that aim to identify sheep with an enhanced ability to resist nematode infection.
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.VETPAR.2013.09.014
Abstract: The presence of gastrointestinal nematode eggs in faecal s les is diagnostic of infection by these parasites. However, this technique cannot be used to distinguish between species of importance. The faecal culture technique and subsequent microscopic analysis of developed larvae is currently used to determine which parasite species are present in the s les, but these techniques take a week to perform and have inherent limitations. To overcome these parasite detection and identification problems, we have developed a DNA extraction method for sheep faeces, and a quantitative multiplex PCR (qPCR) test which can both enumerate and identify Haemonchus, Trichostrongylus and Teladorsagia. We demonstrate that the technique is sensitive to 10 eggs per gram and that dilution of DNA to 0.1 fold can overcome PCR inhibition issues for s les obtained from the field, while maintaining assay sensitivity. Further development of these tests for commercial use is warranted, given their potential to provide consistently faster and more accurate diagnoses of these parasites using simple s le collection and laboratory methods which can be easily adapted for the detection of a variety of pathogens from the same faecal s le.
Publisher: Springer Science and Business Media LLC
Date: 15-08-2010
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.IJPARA.2016.07.001
Abstract: Haemonchus contortus (Barber's pole worm or "BPW") is the nematode "nemesis" of small ruminant production systems in tropical and subtropical regions of the world. Its reputation derives from a combination of high fecundity and a short generational interval that provides an enviable developmental plasticity for adaptation or resistance to control measures. This review critically examines the historical and current literature on the host-parasite-environment interaction for H. contortus, particularly in sheep, to highlight changes in parasite distribution and ecology on pasture, changes to the seasonal inhibition of fourth stage larvae and the most appropriate models to identify protective responses and assess vaccines. The review also proposes pathways to bring host genetics to fruition and avenues where advances in the parasite genome may complement control measures.
Publisher: Elsevier BV
Date: 10-2010
DOI: 10.1016/J.RVSC.2010.02.010
Abstract: Immunoglobulin (Ig) E is actively transported into ovine colostrum. Here we examine the degree of selectivity and the mechanism by which this transfer occurs in sheep. Results indicate that during colostrogenesis in sheep, transfer of immunoglobulins was most selective for IgG1 and IgA followed by IgE, IgM and IgG2. In milk, selectivity was greatest for IgA, followed by IgM, IgE, IgG1 and IgG2. The neonatal Fc receptor (FcRn) and poly immunoglobulin receptor (pIgR) mediate the transport of IgG1 and IgA across the ovine mammary epithelium respectively. In primates and rodents, the low-affinity IgE receptor, Fc epsilonRII, functions to transport IgE across the intestinal epithelium. We therefore investigated the expression of the low-affinity IgE receptor (CD23), pIgR and FcRn transcripts in the ovine mammary gland. The expression profiles of FcRn, pIgR and CD23 mRNA reflected concentrations of their Ig ligands in mammary secretions. These findings suggest a role for CD23 in transport of IgE across the mammary epithelium of sheep.
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.3382/PS/PEZ422
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.IJPARA.2009.09.007
Abstract: Resistance to an acute gastrointestinal nematode (GIN) infection is dependent on the ability of the host to recognise the parasite and mount a protective Th2 response. It is hypothesised that lambs which are genetically susceptible to GIN will differentially up-regulate Th1-type genes and therefore remain susceptible to chronic parasitism compared with genetically resistant lambs which will differentially up-regulate Th2-type genes and clear the parasite infection. Two selection flocks, in which lines of Merino sheep produced lambs genetically resistant or susceptible to GIN, were acutely challenged once or thrice with either Haemonchus contortus or Trichostrongylus colubriformis. Faecal-egg counts (FECs), and plasma and tissue anti-parasite (H. contortus or T. colubriformis) antibody isotype responses showed that resistant animals challenged three times with T. colubriformis established a protective Th2 response (negligible FEC, IgG1 and IgE) whereas susceptible animals required multiple challenges to establish a significant IgG1 response despite FECs remaining high. Trichostrongylus colubriformis elicited a more pronounced host response than H. contortus. RNA extracted from tissues at the site of each parasite infection and associated lymph nodes were interrogated by microarray and quantitative PCR analyses to correlate host gene expression to FECs and antibody responses. The IFN-gamma inducible gene cxcl10 was up-regulated in the susceptible line of the Trichostrongylus selection flock sheep after a tertiary challenge with the parasites H. contortus and T. colubriformis. However, a uniform pattern of genes was not up-regulated in resistant animals from both selection flocks during both parasite infections, suggesting that the mode of host resistance to these parasites is different, although some similarities in host susceptibility were apparent.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.VETPAR.2014.08.009
Abstract: Gastrointestinal nematodes remain a major limitation to the productivity of livestock systems. Selective breeding to produce populations that have an enhanced ability to resist infection is a viable and ongoing option to reduce this impact. The development of new phenotypes that facilitate this process is therefore of great interest. For this reason we explored relationships between haematological parameters and the ability of sheep to resist nematode infection. A multivariate analytical approach was used to define algorithms based on the blood parameters that can be used to rank the ability of sheep to resist nematode infection in a single blood s le and can be applied independent of infection status. The algorithms were shown to classify susceptible sheep with a 100% accuracy and resistant sheep with 80% accuracy. Further development of this platform approach may be an important advance for small ruminant production systems worldwide and might also be applied to other diseases of livestock or even environmental stressors such as heat.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.VETPAR.2016.02.031
Abstract: Resistance to the amino-acetonitrile derivative monepantel has been reported in several species of gastrointestinal nematodes over recent years. We were interested in the use of in vitro assays with free-living worm life-stages to detect resistance to this drug. We therefore used larval development and larval migration assays to examine dose response relationships for the drug against two susceptible and one resistant isolate of Haemonchus contortus. The resistant isolate was established by laboratory propagation of the survivors of a field treatment with Zolvix(®) that had originally resulted in a drug efficacy of over 99%. Drug efficacy against this field-derived laboratory-propagated resistant isolate in vivo was approximately 15%. The larval development assay proved able to discriminate between the susceptible and resistant isolates, with larvae of the resistant isolate showing an ability to develop at higher drug concentrations than the two susceptible isolates. The resistant isolate showed the presence of two distinct subpopulations, separated by a plateau in the dose-response curve. Sub-population 1 (approximately 40% of the total population) showed a low level of resistance with an IC50 increased approximately 7-fold compared to the baseline susceptible isolate, while sub-population 2 (the remaining 60% of the total population) showed an IC50 increased over 1000-fold compared to the baseline susceptible isolate. This level of resistance is unusually high for any gastrointestinal nematode species in drug dose-response in vitro assays. In contrast, the migration assay could not discriminate between the three isolates, with migration not reduced to zero at any of the drug concentrations tested. This study demonstrates that a larval development assay is able to detect resistance to monepantel in H. contortus, and that resistance can exist in two distinct forms. This suggests that at least two separate monepantel resistance mechanisms are acting within the worm isolate studied here, with one or more mechanisms conferring a much higher level of resistance than the other(s).
Publisher: Springer Science and Business Media LLC
Date: 2001
Abstract: Haemoglobin genes have been found in a number of plant species, but the number of genes known has been too small to allow effective evolutionary inferences. We present nine new non-symbiotic haemoglobin sequences from a range of plants, including class 1 haemoglobins from cotton, Citrus and tomato, class 2 haemoglobins from cotton, tomato, sugar beet and canola and two haemoglobins from the non-vascular plants, Marchantia polymorpha (a liverwort) and Physcomitrella patens (a moss). Our molecular phylogenetic analysis of all currently known non-symbiotic haemoglobin genes and a selection of symbiotic haemoglobins have confirmed the existence of two distinct classes of haemoglobin genes in the dicots. It is likely that all dicots have both class 1 and class 2 non-symbiotic haemoglobin genes whereas in monocots we have detected only class 1 genes. The symbiotic haemoglobins from legumes and Casuarina are related to the class 2 non-symbiotic haemoglobins, whilst the symbiotic haemoglobin from Parasponia groups with the class 1 non-symbiotic genes. Probably, there have been two independent recruitments of symbiotic haemoglobins. Although the functions of the two non-symbiotic haemoglobins remain unknown, their patterns of expression within plants suggest different functions. We examined the expression in transgenic plants of the two non-symbiotic haemoglobins from Arabidopsis using promoter fusions to a GUS reporter gene. The Arabidopsis GLB1 and GLB2 genes are likely to be functionally distinct. The class 2 haemoglobin gene (GLB2) is expressed in the roots, leaves and inflorescence and can be induced in young plants by cytokinin treatment in contrast to the class 1 gene (GLB1) which is active in germinating seedlings and can be induced by hypoxia and increased sucrose supply, but not by cytokinin treatment.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.IJPARA.2007.07.012
Abstract: Sheep have a varying ability to resist infection with gastrointestinal nematodes. This ability is due in part to genetic differences that exist between in iduals. In order to define these differences we have used real-time PCR to quantify gene expression responses in the gut mucosal surface of genetically resistant and susceptible sheep, following a nematode challenge. Expression profiles were determined in response to two different nematode species, Haemonchus contortus and Trichostrongylus colubriformis, and in ergent sheep originating from two different genetic backgrounds. Results show that the response generated differs between resistant and susceptible animals and is further impacted by the origin of the sheep and nematode species used for challenge. However, some conserved features of a response mounted by a resistant or a susceptible animal were identified. Genes found to be more abundantly expressed in resistant animals include markers of an early inflammatory response, several Toll-like receptors (TLR2, 4, 9) and free radical producing genes (DUOX1 and NOS2A). Conversely, genes differentiating susceptible animals indicate a prolonged response and development of a chronic inflammatory state, characterised by elevated expression of members of the NF-kappabeta signalling pathway (IKBKB and NFKBIA) together with delayed expression of regulatory markers such as IL2RA (CD25), IL10 and TGFbeta2. While multiple nematode response pathways were identified, the identification of conserved aspects of the response which associate with resistance provides evidence that alternative nematode control strategies, such as breeding for resistant animals, may be feasible.
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.VETPAR.2012.07.017
Abstract: A molecular procedure was developed to detect and quantify larvae of different strongylid parasite species recovered from pasture s les. Two lamb flocks (L and S) grazed separate paddocks with different natural larvae challenges (one low [Paddock L] and one high [Paddock S] challenge) on a commercial farm in Western Australia. Pasture s les were collected and analysed for larvae on 9 separate occasions from each paddock. Pregnant Merino ewes were s led on 3 separate occasions (2 pre-partum and 1 post-partum). Following lambing, 203 female crossbred lambs were identified, from which faecal s les were collected across five separate s lings. Lamb production and faecal attributes were recorded. Genomic DNA was extracted directly from lamb faeces, in addition to the genomic DNA extracts from strongylid larval species recovered from pastures. Faecal worm egg counts (FWECs) were undertaken. Species-specific qPCRs and conventional PCRs (ITS-2 nuclear ribosomal DNA) were used to screen s les for strongylid species (Teladorsagia circumcincta, Trichostrongylus spp., Haemonchus contortus, Chabertia ovina and Oesophagostomum venulosum). Negative correlations (r(2)>0.91) were found between qPCR C(q) values and log-transformed pasture larval counts for Trichostrongylus spp. and T. circumcincta. Moderate levels of agreement between pasture larval counts and qPCR results were observed (67%). A clear difference in pasture larval challenge levels was observed between the two flocks using both qPCR and conventional pasture larval counts. It is difficult to draw conclusions on the production performances of lambs from the two experimental flocks, as no further replicates were able to be conducted following this experiment. Flock L had higher dressing percentages than Flock S (P=0.038), along with significantly higher faecal consistency and breech fleece faecal soiling scores at successive s lings. The molecular procedures utilised in this study have the potential to be beneficial for livestock grazing management strategies and parasite surveillance, however further investigation is necessary before they can become part of routine diagnostics.
Publisher: Wiley
Date: 04-07-2023
DOI: 10.1111/AVJ.13267
Publisher: Wiley
Date: 2010
DOI: 10.1111/J.1365-3024.2009.01156.X
Abstract: To characterize the role of a range of oxidant, antioxidant and mucous-related genes in the primary response to gastrointestinal nematodes, groups of genetically resistant sheep were challenged with either Haemonchus contortus or Trichostrongylus colubriformis and necropsied for retrieval of tissue at days 0, 3, 7, 14 and 21. To determine if the response was localized to the site of parasite infection, four different gut tissues were s led: the abomasum, proximal and distal jejunum and ileum. Basal expression patterns of all candidate genes were determined using the day 0 (pre-challenge) s les. A conserved innate response involving elevated expression of dual oxidase, glutathione peroxidase and trefoil factor was initiated within 3 days of challenge and extended out to 21 days. An increase in host gene expression levels at the preferred site of infection (the abomasum for H. contortus and the proximal jejunum for T. colubriformis) was also common to both nematodes. However, these increases were concomitant with reduced expression in other areas of the gut suggesting a compartmentalized response. Other aspects of the response were parasite-specific, with T. colubriformis challenge inducing expression peaks at times corresponding to nematode life-stage transitions.
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.IJPARA.2012.01.007
Abstract: Gastrointestinal nematodes represent a major production problem for ruminant livestock. Enhancing immunity to gastrointestinal nematodes through vaccination is desirable but mechanistic understanding of initial host responses that facilitate gastrointestinal nematode protective immunity is limited. We hypothesise that gastrointestinal nematode invasion induces mucosal epithelium damage and alarmin (e.g. IL33) release, thereby contributing to initiation of protective gastrointestinal nematode immunity. To test this, an in vitro air-liquid interface human HT-29 epithelial cell-Trichostrongylus colubriformis co-culture system was developed. Exsheathed L3 T. colubriformis exhibited both sinusoidal and burrowing motions in the co-culture system. Burrowing parasites, but not ivermectin-paralysed larvae, induced necrotic death of epithelial cells (annexin V(+) ropidium iodide(+)/caspase 3/7(-)). Microscopy confirmed that larvae consumed labelled necrotic epithelial cell contents. Trichostrongylus colubriformis larvae and their post-exsheathment antigens (excretory/secretory products) significantly induced IL33 mRNA expression in the epithelial cells. Immunoblot confirmed that IL33 was released from epithelial cells due to the damage caused by motile larvae. Exposure of HT-29 cells to alum or Sigma proprietary adjuvants induced significant epithelial cell IL33 mRNA expression without inducing cellular necrosis. Hence, the intracellular contents were not released externally where they might exert alarmin activity and this may limit their ability to trigger a protective anti-gastrointestinal nematode response. We conclude that T. colubriformis motion at the infection site induces intestinal epithelial cell necrosis which facilitates the release of intracellular contents, including IL33, and may be fundamental to the initiation of an appropriate host response to gastrointestinal nematodes. Our co-culture model is useful for studying initial epithelial cell-parasite interactions without conducting expensive animal trials.
Publisher: Elsevier BV
Date: 05-2018
DOI: 10.1016/J.VETPAR.2018.04.009
Abstract: Reliable methods for detection of A. galli infection using excreta egg count (EEC) and ELISA assays to determine A. galli specific IgY levels in serum and yolk s les were compared from hens infected naturally and artificially. Artificially infected hens were used to generate s les for analysis of preferred detection methods and to generate contaminated ranges for use in the naturally acquired infection study in which Lohmann Brown hens (n = 200) at 16 weeks of age were randomly assigned to four treatments with five replicate pens. Hens of negative control (NC) ranged on a decontaminated area, hens of low infection, medium infection and positive control (PC) ranged on the areas previously contaminated by hens artificially infected with 250, 1000 and 2500 A. galli eggs/hen, respectively. Additionally, hens of PC were orally infected with 1000 A. galli eggs/hen. Anti A. galli antibody levels in hen serum (SIgY) and yolk (YIgY) were measured before range access, and 2, 7 and 12 weeks after access to the contaminated ranges. In a natural infection study, eggs were detected in the excreta of all hens 4 weeks after range access, with the exception of NC in which no eggs were detected. EEC increased to reach maximum value (2204 ± 307 eggs/g) after 11 weeks of range access and then declined at 12 weeks (905 ± 307eggs/g) (p < 0.01). While SIgY OD values were not different in hens between any groups before range access, after 2 weeks, both SIgY and YIgY gradually increased in hens of PC (1.17 ± 0.03 and 0.88 ± 0.04) and medium infection (1.07 ± 0.03 and 0.96 ± 0.04) compared to low infection (0.38 ± 0.03 and 0.29 ± 0.04) (p < 0.01) and NC. After 12 weeks, SIgY were similar in hens of PC, medium and low groups whereas YIgY was higher in hens of low infection group (p < 0.01). Sensitivity of the serum and egg yolk antibody levels assay to detect A. galli infection was 100% and 96%, respectively, whereas the pooled EEC method yielded a sensitivity of 93%. The results of this study suggest that hens naturally infected with A. galli produce both SIgY and YIgY at different levels depending on the infection intensity and duration of exposure which allows the diagnosis of prior infection or early diagnosis of current infection. Use of the practical and non-invasive method of yolk s le analysis for detecting IgY can be just as informative as using serum s les to detect A. galli infection.
Publisher: Elsevier BV
Date: 1997
Publisher: International Society for Horticultural Science (ISHS)
Date: 07-2009
Publisher: Elsevier BV
Date: 12-2012
Publisher: Springer Science and Business Media LLC
Date: 10-09-2008
DOI: 10.1007/S00122-008-0870-8
Abstract: High resolution melting curve (HRM) is a recent advance for the detection of SNPs. The technique measures temperature induced strand separation of short PCR licons, and is able to detect variation as small as one base difference between s les. It has been applied to the analysis and scan of mutations in the genes causing human diseases. In plant species, the use of this approach is limited. We applied HRM analysis to almond SNP discovery and genotyping based on the predicted SNP information derived from the almond and peach EST database. Putative SNPs were screened from almond and peach EST contigs by HRM analysis against 25 almond cultivars. All 4 classes of SNPs, INDELs and microsatellites were discriminated, and the HRM profiles of 17 licons were established. The PCR licons containing single, double and multiple SNPs produced distinctive HRM profiles. Additionally, different genotypes of INDEL and microsatellite variations were also characterised by HRM analysis. By sequencing the PCR products, 100 SNPs were validated/revealed in the HRM licons and their flanking regions. The results showed that the average frequency of SNPs was 1:114 bp in the genic regions, and transition to transversion ratio was 1.16:1. Rare allele frequencies of the SNPs varied from 0.02 to 0.5, and the polymorphic information contents of the SNPs were from 0.04 to 0.53 at an average of 0.31. HRM has been demonstrated to be a fast, low cost, and efficient approach for SNP discovery and genotyping, in particular, for species without much genomic information such as almond.
Publisher: Informa UK Limited
Date: 20-06-2017
DOI: 10.1080/03079457.2017.1330536
Abstract: Broilers commonly suffer from necrotic enteritis (NE). Other gastrointestinal infectious diseases affect poultry, including nematode infections which are considered a re-emerging disease in barn and free-range systems. The aim of this study was to characterize the immune response of broilers after artificial infection with NE and contrast these with responses to the nematode Ascaridia galli and determine whether immune parameters measured during the course of infection can be used to distinguish infected from uninfected birds. A total of 96 one-day-old male Ross 308 broiler chickens were used in this study. At 10 days of age, broilers were randomly assigned to one of the following treatment groups: control birds (n = 32), A. galli infected birds (n = 32), or NE infected birds (n = 32) and inoculated with the appropriate infective agents. The immune response of birds was monitored through evaluation of haematology parameters, acute phase protein production, and intraepithelial intestinal lymphocyte population changes at 11, 16, 20, and 32 days of age. T-helper cells (CD4
Publisher: Cambridge University Press (CUP)
Date: 16-10-2010
DOI: 10.1017/S0031182009991521
Abstract: The use of DNA markers to track the development of anthelmintic resistance in parasites of livestock would allow informed choices for the management of this important problem. We describe a genetic mapping approach for the discovery of DNA markers for anthelmintic resistance in Haemonchus contortus . We crossed a multi-drug resistant field isolate of H. contortus with a well-characterized laboratory strain susceptible to 4 drug classes. The F 2 were separately selected with 5 anthelmintics from 4 drug classes, producing drug-resistant populations carrying gene variants derived from both the field isolate and the laboratory strain. In idual F 2 worms were analysed using licon length polymorphisms (ALPs). We looked for field isolate alleles over- or under-represented in F 2 populations compared to the unselected F 2 and/or the laboratory strain. The data we obtained suggest that marker association can be used to link neutral markers with resistance, but also that more markers and perhaps more inbred laboratory strains would make the procedure more likely to succeed.
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.VETPAR.2011.05.007
Abstract: Gastrointestinal nematodes are a major problem for pastoral ruminant production systems. This problem could be reduced by the application of breeding strategies that select for nematode resistant sheep, but no suitable molecular markers are available. Research selection flocks containing lines that are resistant (R) or susceptible (S) to gastrointestinal nematodes provide an excellent resource for discovering selectable markers, and for studying the underlying mechanisms of an effective anti-nematode response. In this study we have used a combination of quantitative real time PCR assays and ELISA to determine if nematode challenge impacts on the expression of the satiety-regulating hormone ghrelin. The expression responses were then compared between the selection flock R and S lines. The results show that the basal levels of ghrelin in plasma were greater than 2-fold higher in nematode naïve S line sheep. Three days after a primary nematode challenge ergent ghrelin expression patterns were observed between the selection lines, with levels increasing in R sheep while decreasing in S sheep. After a secondary challenge this trend was repeated, but following a third challenge ghrelin expression levels rose in both R and S sheep, by which time the S animals had acquired an effective immune response to the nematodes, as measured by a significant reduction in faecal egg output. Importantly, this phenomenon was observed in gene expression studies in gut tissues and also in ELISA measurements of ghrelin peptide levels in plasma. A regression analysis showed that ghrelin transcript expression in the gut accounted for >40% of the variation in faecal egg count measured following Haemonchus or Trichostrongylus infection. We therefore hypothesise that the direction of ghrelin expression (up or down) immediately following nematode exposure may play an important role in regulating the differing anti-nematode responses that occur in the R and S lines. Such differences identify ghrelin as a previously unrecognized factor influencing the acquisition of immunity to nematodes.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.VETPAR.2019.05.007
Abstract: Breeding for resistance to gastrointestinal nematodes (GIN) in sheep relies largely on the use of worm egg counts (WEC) to identify animals that are able to resist infection. As an alternative to such measures of parasite load we aimed to develop a method to identify animals showing resistance to GIN infection based on the impact of the infection on blood parameters. We hypothesized that blood parameters may provide a measure of infection level with a blood-feeding parasite through perturbation of red blood cell parameters due to feeding behaviour of the parasite, and white blood cell parameters through the mounting of an immune response in the host animal. We measured a set of blood parameters in 390 sheep that had been exposed to an artificial regime of repeated challenges with Trichostrongylus colubriformis followed by Haemonchus contortus. A simple analysis revealed strong relationships between single blood parameters and WECs with correlation coefficients -0.54 to -0.60. We then used more complex multi-variate methods based on supervised classifier models (including Bayesian Network) as well as regression models (Lasso and Elastic Net) to study the relationships between WECs and blood parameters, and derived algorithms describing the relationships. The ability of these algorithms to classify sheep GIN resistance status was tested using the WEC and blood parameters collected from a different group of 418 sheep that had acquired natural infections of H. contortus from pasture. We identified the most resistant and most susceptible animals (10% percentiles) of this group based on WECs, and then compared the identities of these animals to the identities of animals that were predicted to be most resistant and most susceptible by our algorithms. The models showed varying abilities to predict susceptible and resistant sheep, with up to 65% of the most susceptible animals and 30% of the most resistant animals identified by the Elastic Net model algorithms. The prediction algorithms derived from female sheep data performed better than those for male sheep in some cases, with the predicted animals accounting for up to 50-60% of the actual resistant and susceptible female animals. Heritability values were calculated for blood parameters and the aggregate trait descriptions defined by the novel prediction algorithms. The aggregate trait descriptions were moderately heritable and may therefore be suitable for use in genetic selection strategies. The present study indicates that multivariate models based on blood parameter data showed some ability to predict the resistance status of sheep to infection with H. contortus.
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.MOLBIOPARA.2021.111424
Abstract: Although many important mediators and critical pathways are found to be involved in host immune responses to Haemonchus contortus infection, the initial responses to infection in the naïve and in the previously exposed state have not been compared at the transcriptional level. To further understand the development of adaptive immunity to H. contortus infection, we compared the early abomasal gene expression patterns between a primary and a tertiary challenge for four lines of sheep to discover differentially expressed genes (DEGs). The sheep were from the resistant (R) and susceptible (S) lines of two flocks of sheep selected for ergent responses to gastro-intestinal parasites (HSF and TSF). The flocks have separate origins and were initiated using two different strains of Merino sheep. One of the DEGs, mast cell proteinase 1, had significantly lower expression in tertiary compared to primary infections for all four lines of sheep. This gene was not identified in previous studies where resistant and susceptible sheep s les were compared within infection time points. Comparing the differentially expressed genes (DEGs) for the two R lines reveals that responses differed very little between the primary and tertiary challenges for HSFR and only two genes were identified, in contrast to the TSFR where there were 134 genes identified including the two identified using the HSFR animals. Similarly, comparing the primary and tertiary challenges for HSFS identified 15 DEGs, whilst for TSFS there were 128 DEGs identified. It is surprising that so few genes respond similarly between the two challenge regimes across the four lines of sheep, and suggests significant differences in immune mechanisms between the two flocks (across the lines) and also between the lines within flocks. Our results offer a quantitative snapshot comparing the transcriptome in the ovine abomasum between primary and tertiary infections with H. contortus in both genetically resistant and susceptible sheep.
Publisher: Elsevier BV
Date: 03-2000
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.IJPARA.2007.11.001
Abstract: We believe this study is the first to consider the genetic and phenotypic ergence between isolates of Haemonchus contortus in Australia. Microsatellite markers have been used to investigate genetic ergence, whilst phenotypic ergence has been considered through in idual worm morphology, isolate life history traits and the effect of isolates upon the host. The results are discussed in the context of the likely introduction of H. contortus to Australia, its recent isolation, and the characteristics of sheep and goat farming which might act to either isolate or distribute parasites. We conclude that there is significant observable genetic ergence between isolates of H. contortus in Australia. The ergence may have been under-estimated in this study due to a variety of factors. Phenotypic ergence is also observed, and potentially has significant implications for both economic losses due to haemonchosis on in idual properties and for decisions regarding the regulation of stock movements in Australia.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.3382/PS/PEX347
Abstract: This study was conducted to determine the effect of Ascaridia galli infection on free-range laying hens. Lohmann Brown laying hens (n = 200) at 17 wk of age were allocated to 4 treatment groups (n = 50 per group), each with 5 replicate pens of 10 hens. Hens in 3 treatment groups were orally inoculated with different doses of embryonated A. galli eggs: low (250 eggs), medium (1,000 eggs), and high (2,500 eggs) levels, whereas hens of the control group were not infected. Infection levels were monitored using excreta egg counts and mature A. galli worm counts in the intestine. Anti A. galli antibody titers (IgY) in the serum were measured prior to infection, and at 6, 11, 15, and 20 wk post infection (PI) and in egg yolk at 11 and 20 wk PI. Parameters evaluated included feed intake, egg production, egg weight, egg mass, FCR, liver weight, liver fat, and intra epithelial immune cell infiltration. The results showed no difference in feed intake, body weight, or FCR among any treatment groups (P > 0.05). Egg production was lower in the low infection group compared to other groups at 20 wk of age (P < 0.01). Serum IgY was higher in the infected groups' hens at 20 wk PI compared to control group hens (P < 0.01). Yolk IgY increased significantly over time and was higher in infected hens compared to hens of the control group at 11 and 20 wk PI (P < 0.001). No differences were observed in liver lipid content or intraepithelial lymphocytes infiltration among treatment groups. Ascaridia galli eggs in the coprodeum content and adult A. galli worm count were higher in infected hens compared to hens of the control group (P < 0.01). In conclusion, the effects of artificial infection with A. galli on the parameters investigated were minor, and egg yolk antibody may be a more reliable indicator of A. galli infection than serum antibody or excreta egg count.
Publisher: CSIRO Publishing
Date: 14-03-2023
DOI: 10.1071/AN22228
Abstract: Context The winter feed gap is a common problem for livestock grazing systems worldwide, and changes to climate have made these deficits more unpredictable and extreme. Dual-purpose crops are an important tool in many southern Australian mixed crop–livestock systems to help fill the winter feed gap. Providing more reliable feed over winter can remove feed constraints and allow for earlier lambing in autumn with potential whole-farm system benefits. Aims We simulated a whole-farm livestock enterprise in the Agricultural Production Systems Simulator (APSIM) to examine the implications of spring- and autumn-lambing systems relying on a standard pasture-only feedbase compared with a farm where 25% of its grazed area is allocated to dual-purpose crops. Methods Twelve simulations were run across four locations in New South Wales, Australia, that varied in climatic conditions (both rainfall total and distribution) including two lambing systems (spring vs autumn) × two feedbase types (100% pasture vs 75% pasture and 25% dual-purpose crops) × three stocking densities. Key results For autumn-lambing systems, integrating dual-purpose crops helped to fill the winter feed gap and reduced supplement demand on average by ~28% compared with a pasture-only system. Compared with the standard pasture-only spring-lambing system, integrating dual-purpose crops into spring- and autumn-lambing systems more than doubled gross margin returns due to economic grain yield and lower supplement demand. A shift from spring- to autumn-lambing facilitated by dual-purpose crops also led to better reproductive performance of ewes in the subsequent year. In higher-rainfall, cooler environments, autumn-lambing systems with dual-purpose crops had the highest system gross margins, lowest economic risk and allowed for a safe increase in stocking density. In lower-rainfall, warmer environments, integration of dual-purpose crops into spring-lambing systems returned marginally higher gross margins than for the autumn-lambing system, but differences were less apparent at high stocking density. In lower-rainfall environments, dual-purpose crops helped to mitigate some of the economic risk, but the benefits were less clear. Conclusions We show dual-purpose crops can help fill the winter feed gap and support earlier lambing in autumn across a range of environments, especially in higher-rainfall cooler environments, with significant improvements in total farm gross margins. Implications Integrating dual-purpose crops will enable farmers to change their livestock system to mitigate their risks, reduce supplementary feeding and capitalise on other potential benefits, such as improved marketing and avoiding animal health problems.
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.IJPARA.2009.03.002
Abstract: We evaluated a combined microscopic-molecular approach for the diagnosis of key strongylid infections in sheep using panels of well-defined control and test s les. The method established is based on the separation of nematode eggs from faecal s les using a salt flotation procedure, the extraction and column-purification of genomic DNA, followed by real-time PCR and melting-curve analysis. Specific and semi-quantitative lification from (a minimum of 0.1-2.0pg) genomic DNA of Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp., Cooperia oncophora, Oesophagostomum columbianum, Oesophagostomum venulosum or Chabertia ovina is achieved using a specific, forward oligonucleotide primer located in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) together with a conserved reverse primer in the large subunit of rDNA. Using a panel of well-defined genomic DNA s les from eggs from sheep monospecifically infected with H. contortus or Te. circumcincta, there was a correlation between cycle threshold (Ct) values in the PCR and numbers of egg per gram of faeces, thus allowing the semi-quantitation of parasite DNA in faeces. The findings of the present study indicate that a microscopic-molecular approach provides a useful tool for diagnosis, for epidemiological and ecological surveys as well as for integration into parasite monitoring, drug resistance (i.e. 'egg count reduction') testing or control programmes, particularly following semi- or full-automation.
Publisher: Springer Science and Business Media LLC
Date: 24-01-2019
Publisher: Wiley
Date: 18-04-2006
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.BIOTECHADV.2008.03.003
Abstract: Parasitic nematodes of livestock have a major economic impact worldwide. In spite of the health problems caused by nematodes and advances toward the development of vaccines and new therapeutic agents against some of them, relatively limited attention has been paid to the need for improved, practical methods of diagnosis. Accurate diagnosis and genetic characterization of parasitic nematodes of livestock are central to their effective control, particularly given the current, serious problems with anthelmintic resistance in nematode populations. Traditional diagnostic techniques have considerable limitations, and there have been some advances toward the development of molecular-diagnostic tools. This article provides a brief account of the significance of parasitic nematodes (order Strongylida), reviews the techniques that have been evaluated or used for diagnosis and describes developments in polymerase chain reaction (PCR)-based methods for the specific diagnosis of nematode infection/s and the genetic characterisation of the causative agents. The advances made in recent years provide a solid foundation for the development of practical, highly sensitive and specific diagnostic tools for epidemiological investigations and for use in control programmes.
Publisher: Elsevier BV
Date: 12-2014
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/AN19705
Abstract: Context In Australia and many other countries, free-range eggs can be sold at significantly higher prices than cage eggs. Mislabelling cage eggs as free-range eggs and vice versa has been documented, and has a significant impact on consumer trust and egg consumption. The development of methods to identify eggs produced from different production systems is necessary to satisfy consumer demand. Aims The objective of this study was to determine whether eggshell mineral composition could be used as a way to differentiate eggs originating from each production system. Our hypothesis was that birds with access to soil would have higher levels of trace minerals in shells. Methods Eggs were randomly collected from six commercial caged and six commercial free-range flocks in Australia. Twelve eggshell s les from each flock were analysed for mineral composition (Ca, P, Mg, Na, Al, B, Cu, Mn, Fe, K, S and Zn) by using inductively coupled plasma-optical emission spectrometry. Key results The results showed that free-range eggshells contained significantly higher contents of macro-minerals (P, Mg and Na) but lower contents of micro-minerals (Cu, Fe, K, S and Mn) than the cage eggshells (P & 0.05). For all minerals measured, a high variability was noted within and between production systems. Conclusions Analysis of eggshell mineral composition may not be effective for determining the origin of eggs. Implications Systematic studies of the bird’s environment, including analysis of mineral composition in diets, pastures, soil and drinking water are required for comprehensive evaluation of the influences of production systems of laying hens on mineral composition of eggs and eggshells.
Publisher: Springer Science and Business Media LLC
Date: 09-10-2010
Abstract: Despite a high genetic similarity to peach, almonds ( Prunus dulcis ) have a fleshless fruit and edible kernel, produced as a crop for human consumption. While the release of peach genome v1.0 provides an excellent opportunity for almond genetic and genomic studies, well-assessed segregating populations and the respective saturated genetic linkage maps lay the foundation for such studies to be completed in almond. Using an almond intraspecific cross between 'Nonpareil' and 'Lauranne' (N × L), we constructed a moderately saturated map with SSRs, SNPs, ISSRs and RAPDs. The N × L map covered 591.4 cM of the genome with 157 loci. The average marker distance of the map was 4.0 cM. The map displayed high synteny and colinearity with the Prunus T × E reference map in all eight linkage groups (G1-G8). The positions of 14 mapped gene-anchored SNPs corresponded approximately with the positions of homologous sequences in the peach genome v1.0. Analysis of Mendelian segregation ratios showed that 17.9% of markers had significantly skewed genotype ratios at the level of P 0.05. Due to the large number of skewed markers in the linkage group 7, the potential existence of deleterious gene(s) was assessed in the group. Integrated maps produced by two different mapping methods using JoinMap ® 3 were compared, and their high degree of similarity was evident despite the positional inconsistency of a few markers. We presented a moderately saturated Australian almond map, which is highly syntenic and collinear with the Prunus reference map and peach genome V1.0. Therefore, the well-assessed almond population reported here can be used to investigate the traits of interest under Australian growing conditions, and provides more information on the almond genome for the international community.
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Peter Hunt.