ORCID Profile
0000-0002-9142-2107
Current Organisation
Australian National University
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Central Nervous System | Neurosciences | Biochemistry And Cell Biology Not Elsewhere Classified | Neurogenetics | Genetics | Medical Biotechnology | Medical Biochemistry: Proteins And Peptides | Medical Microbiology | Gene Expression | Neurology And Neuromuscular Diseases | Organometallic Chemistry | Innate Immunity | Animal Physiology—Systems | Medical Parasitology | Medical Biotechnology Diagnostics (incl. Biosensors) | Photonics, Optoelectronics and Optical Communications |
Nervous system and disorders | Plastic products (incl. Construction materials) | Endocrine organs and diseases (incl. diabetes) | Biological sciences | Living resources (flora and fauna) | Field crops not elsewhere classified | Diagnostic Methods | Medical Instruments | Disease distribution and transmission | Blood Disorders | Cancer and Related Disorders | Immune System and Allergy | Infectious Diseases
Publisher: Springer Science and Business Media LLC
Date: 26-10-2015
Publisher: Springer Science and Business Media LLC
Date: 29-07-2015
Publisher: Cold Spring Harbor Laboratory
Date: 08-03-2017
DOI: 10.1101/114959
Abstract: Allelic heterogeneity is a common phenomenon where a gene exhibit different phenotype depending on the nature of its genetic mutations. In the context of genes affecting malaria susceptibility, it allowed us to explore and understand the intricate host-parasite interactions during malaria infections. In this study, we described a gene encoding erythrocytic ankyrin-1 ( Ank-1 ) which exhibits allelic-dependent heterogeneous phenotypes during malaria infections. We conducted an ENU mutagenesis screen on mice and identified two Ank-1 mutations, one resulted in an amino acid substitution (MRI95845), and the other a truncated Ank-1 protein (MRI96570). Both mutations caused hereditary spherocytosis-like phenotypes and confer differing protection against Plasmodium chabaudi infections. Upon further examination, the Ank-1 (MRI96570) mutation was found to inhibit intra-erythrocytic parasite maturation, whereas Ank-1 (MW95845) caused increased bystander erythrocyte clearance during infection. This is the first description of allelic heterogeneity in ankyrin-1 from the direct comparison between two Ank-1 mutations. Despite the lack of direct evidence from population studies, this data further supported the protective roles of ankyrin-1 mutations in conferring malaria protection. This study also emphasized the importance of such phenomenon to achieve a better understanding of host-parasite interactions, which could be the basis of future studies.
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.NBD.2011.01.003
Abstract: Absence-like seizures in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS) model are believed to arise in hyperexcitable somatosensory cortical neurons, however the cellular basis of this increased excitability remains unknown. We have previously shown that expression of the Transmembrane AMPA receptor Regulatory Protein (TARP), stargazin, is elevated in the somatosensory cortex of GAERS. TARPs are critical regulators of the trafficking and function of AMPA receptors. Here we examine the developmental expression of stargazin and the impact this may have on AMPA receptor trafficking in the GAERS model. We show that elevated stargazin in GAERS is associated with an increase in AMPA receptor proteins, GluA1 and GluA2 in the somatosensory cortex plasma membrane of adult epileptic GAERS. Elevated stargazin expression is not seen in the epileptic WAG/Rij rat, which is a genetically distinct but phenotypically similar rat model also manifesting absence seizures, indicating that the changes seen in GAERS are unlikely to be a secondary consequence of the seizures. In juvenile (6 week old) GAERS, at the age when seizures are just starting to be expressed, there is elevated stargazin mRNA, but not protein expression for stargazin or the AMPA receptor subunits. In neonatal (7 day old) pre-epileptic GAERS there was no alteration in stargazin mRNA expression in any brain region examined. These data demonstrate that stargazin and AMPA receptor membrane targeting is altered in GAERS, potentially contributing to hyperexcitability in somatosensory cortex, with a developmental time course that would suggest a pathophysiological role in the epilepsy phenotype.
Publisher: Springer Science and Business Media LLC
Date: 11-12-2004
Publisher: Proceedings of the National Academy of Sciences
Date: 13-10-2005
Abstract: Chronic microbial infections are associated with fibrotic and inflammatory reactions known as granulomas showing similarities to wound-healing and tissue repair processes. We have previously mapped three leishmaniasis susceptibility loci, designated lmr1 , - 2 , and - 3 , which exert their effect independently of T cell immune responses. Here, we show that the wound repair response is critically important for the rapid cure in murine cutaneous leishmaniasis caused by Leishmania major . Mice congenic for leishmaniasis resistance loci, which cured their lesions more rapidly than their susceptible parents, also expressed differentially genes involved in tissue repair, laid down more ordered collagen fibers, and healed punch biopsy wounds more rapidly. Fibroblast monolayers from these mice repaired in vitro wounds faster, and this process was accelerated by supernatants from infected macrophages. Because these effects are independent of T cell-mediated immunity, we conclude that the rate of wound healing is likely to be an important component of innate immunity involved in resistance to cutaneous leishmaniasis.
Publisher: Informa UK Limited
Date: 13-05-2013
DOI: 10.4161/CIB.23653
Publisher: Oxford University Press (OUP)
Date: 1986
Abstract: We have determined the nucleotide sequence of the gene encoding the ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum, an antigen that has been shown to confer protective immunity on monkeys. The sequence has enabled us to predict the structure of the RESA gene and the amino acid sequence of its protein product. The gene consists of two exons with a short intron located near the 5' end of the coding region. A hydrophobic amino acid segment predicted for the 3' end of exon 1 is consistent with the possibility that exon 1 encodes trafficking signal sequences. We show that restriction fragment length polymorphisms can be used to define two different alleles of RESA, represented by isolates FC27 and NF7, and compare the FC27 sequence with that of a long cDNA clone from NF7 described previously.
Publisher: Public Library of Science (PLoS)
Date: 22-04-2015
Publisher: Proceedings of the National Academy of Sciences
Date: 30-07-2002
Abstract: There is a great difference in susceptibility to v- abl transgene-induced plasmacytoma between the BALB/cAn and the relatively resistant C57BL/6J mouse strains. We have used the Mapmaker/SURVIVOR algorithm to analyze genome-wide scans on over 800 transgenic F 2 hybrid mice, and have mapped at least six loci on chromosomes 2, 4, 11, 17, and 18 that modify tumor-related morbidity. As in human multiple myeloma, males were found to be more prone to plasmacytomagenesis. Different loci influence tumor susceptibility in male and female mice. Survival in females may be largely controlled by a pair of interacting loci on chromosomes 2 and 17.
Publisher: Wiley
Date: 10-07-2012
DOI: 10.1111/J.1528-1167.2012.03585.X
Abstract: We aimed to refine the phenotypic spectrum and map the causative gene in two families with familial focal epilepsy with variable foci (FFEVF). A new five-generation Australian FFEVF family (A) underwent electroclinical phenotyping, and the original four-generation Australian FFEVF family (B) (Ann Neurol, 44, 1998, 890) was re-analyzed, including new affected in iduals. Mapping studies examined segregation at the chromosome 22q12 FFEVF region. In family B, the original whole genome microsatellite data was reviewed. Five subjects in family A and 10 in family B had FFEVF with predominantly awake attacks and active EEG studies with a different phenotypic picture from other families. In family B, reanalysis excluded the tentative 2q locus reported. Both families mapped to chromosome 22q12. Our results confirm chromosome 22q12 as the solitary locus for FFEVF. Both families show a subtly different phenotype to other published families extending the clinical spectrum of FFEVF.
Publisher: Springer Science and Business Media LLC
Date: 20-05-2005
DOI: 10.1007/S00439-005-1296-X
Abstract: Primary open-angle glaucoma (POAG) is one of the leading causes of blindness in the world. It is a clinically variable group of diseases with the majority of cases presenting as the late onset adult type. Several chromosomal loci have been implicated in disease aetiology, but causal mutations have only been identified in a small proportion of glaucoma. We have previously described a large six-generation Tasmanian family with POAG exhibiting genetic heterogeneity. In this family, approximately one third of affected in iduals presented with a glutamine-368-STOP (Q368STOP) mutation in the myocilin gene. We now use a Markov Chain Monte Carlo (MCMC) method to identify a second disease region in this family on the short arm of chromosome 3. This disease locus was initially mapped to the marker D3S1298 and a subsequent minimum disease region of 9 cM between markers D3S1298 and D3S1289 was identified through additional mapping. The region did not overlap with any previously described locus for POAG. Using a multiplicative relative risk model, we identified a positive association between this region and the Q368STOP mutation of myocilin on chromosome 1 in affected in iduals. These findings provide evidence of a new autosomal dominant glaucoma locus on the short arm of chromosome 3.
Publisher: Springer Science and Business Media LLC
Date: 30-11-2011
DOI: 10.1007/S00335-010-9302-6
Abstract: Malaria is a disease that infects over 500 million people, causing at least 1 million deaths every year, with the majority occurring in developing countries. The current antimalarial arsenal is becoming dulled due to the rapid rate of resistance of the parasite. However, in populations living in malaria-endemic regions there are many ex les of genetic-based resistance to the severe effects of the parasite Plasmodium. Defining the genetic factors behind host resistance has been an area of great scientific interest over the last few decades this review summarizes the current knowledge of the genetic loci involved. Perhaps the lessons learned from the natural variation in both the human populations and experimental mouse models of infection may pave the way for novel resistance-proof antimalarials.
Publisher: Wiley
Date: 08-2010
DOI: 10.1111/J.1365-2141.2010.08267.X
Abstract: A family history of a haematological malignancy (HM) is known to be a risk factor for HMs. However, collections of large families with multiple cases of varied disease types are relatively rare. We describe a collection of 12 families with dense aggregations of multiple HM subtypes. Cases were ascertained from a population based study conducted between 1972 and 1980 in Tasmania, Australia. Diagnoses were confirmed through review and re-examination of stored tissue, pathology reports, Tasmanian Cancer Registry and flow cytometry records. Family trees were generated and kinship coefficients were calculated for all pairs of affected in iduals. 120 cases were found in these families. Cases diagnosed with chronic lymphocytic leukaemia (CLL) demonstrated the most significantly increased aggregation (P 53 years), did not aggregate together in families with disease that presented at an earlier age (<20 years) (P = 0.009).
Publisher: Cold Spring Harbor Laboratory
Date: 31-08-2016
DOI: 10.1101/072587
Abstract: Genetic defects in various red blood cell (RBC) cytoskeletal proteins have been long associated with changes in susceptibility towards malaria infection. In particular, while ankyrin (Ank-1) mutations account for approximately 50% of hereditary spherocytosis (HS) cases, an association with malaria is not well-established, and conflicting evidence has been reported. We describe a novel N-ethyl-N-nitrosourea (ENU)-induced ankyrin mutation MRI61689 that gives rise to two different ankyrin transcripts: one with an introduced splice acceptor site resulting a frameshift, the other with a skipped exon. Ank-1 (MRI61689/+) mice exhibit an HS-like phenotype including reduction in mean corpuscular volume (MCV), increased osmotic fragility and reduced RBC deformability. They were also found to be resistant to rodent malaria Plasmodium chabaudi infection. Parasites in Ank-1 (MRI61689/+) erythrocytes grew normally, but red cells showed resistance to merozoite invasion. Uninfected Ank-1 (MRI61689/+) erythrocytes were also more likely to be cleared from circulation during infection the “bystander effect”. This increased clearance is a novel resistance mechanism which was not observed in previous ankyrin mouse models. We propose that this bystander effect is due to reduced deformability of Ank-1 (MRI61689/+) erythrocytes. This paper highlights the complex roles ankyrin plays in mediating malaria resistance.
Publisher: Cold Spring Harbor Laboratory
Date: 12-06-2002
DOI: 10.1101/GR.GR-1578R
Publisher: American Society of Hematology
Date: 12-2004
DOI: 10.1182/BLOOD-2004-06-2234
Abstract: In most myeloid leukemias induced in mice by γ-radiation, one copy of chromosome 2 has suffered a deletion. To search for a potential tumor suppressor gene in that region, we have delineated the deletions in a panel of these tumors. A commonly deleted region of 2 megabase pairs (Mbp) includes the gene encoding the PU.1 transcription factor, a powerful inducer of granulocytic/monocytic differentiation. Significantly, in 87% of these tumors the remaining PU.1 allele exhibited point mutations in the PU.1 DNA binding domain. Surprisingly, 86% of these mutations altered a single CpG, implicating deamination of deoxycytidine, a common mutational mechanism, as the origin of this lesion. The “hot spot” resides in the codon for a contact residue essential for DNA binding by PU.1. In keeping with a tumor suppressor role for PU.1, enforced expression of wild-type PU.1 in the promyelocytic leukemia cells inhibited their clonogenic growth, induced monocytic differentiation, and elicited apoptosis. The mutant PU.1 found in tumors retained only minimal growth suppressive function. The results suggest that PU.1 normally suppresses development of myeloid leukemia by promoting differentiation and that the combination of gene deletion and a point mutation that impairs its ability to bind DNA is particularly leukemogenic.
Publisher: Rockefeller University Press
Date: 05-05-1997
Abstract: In Leishmaniasis, as in many infectious diseases, clinical manifestations are determined by the interaction between the genetics of the host and of the parasite. Here we describe studies mapping two loci controlling resistance to murine cutaneous leishmaniasis. Mice infected with L. major show marked genetic differences in disease manifestations: BALB/c mice are susceptible, exhibiting enlarging lesions that progress to systemic disease and death, whereas C57BL/6 are resistant, developing small, self-healing lesions. F2 animals from a C57BL/6 × BALB/c cross showed a continuous distribution of lesion score. Quantitative trait loci (QTL) have been mapped after a non-parametric QTL analysis on a genome-wide scan on 199 animals. QTLs identified were confirmed in a second cross of 271 animals. Linkage was confirmed to a chromosome 9 locus (D9Mit67–D9Mit71) and to a region including the H2 locus on chromosome 17. These have been named lmr2 and lmr1, respectively.
Publisher: American Society for Microbiology
Date: 06-2010
DOI: 10.1128/IAI.00126-10
Abstract: Genetic linkage studies of the host response to Leishmania major , the causative agent of cutaneous leishmaniasis, have identified significant genetic complexity in humans and mice. In the mouse model, multiple loci have been implicated in susceptibility to infection, but to date, the genes underlying these loci have not been identified. We now describe the contribution of a novel candidate gene, Fli1 , to both L. major resistance and enhanced wound healing. We have previously mapped the L. major response locus, lmr2 , to proximal chromosome 9 in a genetic cross between the resistant C57BL/6 strain and the susceptible BALB/c strain. We now show that the presence of the resistant C57BL/6 lmr2 allele in susceptible BALB/c mice confers an enhanced L. major resistance and wound healing phenotype. Fine mapping of the lmr2 locus permitted the localization of the lmr2 quantitative trait locus to a 5-Mb interval comprising 21 genes, of which microarray analysis was able to identify differential expression in 1 gene— Fli1 . Analysis of Fli1 expression in wounded and L. major -infected skin and naïve and infected lymph nodes validated the importance of Fli1 in lesion resolution and wound healing and identified 3 polymorphisms in the Fli1 promoter, among which a GA repeat element may be the important contributor.
Publisher: Springer Science and Business Media LLC
Date: 25-01-2007
DOI: 10.1007/S00439-007-0323-5
Abstract: Dense sets of hundreds of thousands of markers have been developed for genome-wide association studies. These marker sets are also beneficial for linkage analysis of large, deep pedigrees containing distantly related cases. It is impossible to analyse jointly all genotypes in large pedigrees using the Lander-Green Algorithm, however, as marker density increases it becomes less crucial to analyse all in iduals' genotypes simultaneously. In this report, an approximate multipoint non-parametric technique is described, where large pedigrees are split into many small pedigrees, each containing just two cases. This technique is demonstrated, using phased data from the International Hapmap Project to simulate sets of 10,000, 50,000 and 250,000 markers, showing that it becomes increasingly accurate as more markers are genotyped. This method allows routine linkage analysis of large families with dense marker sets and represents a more easily applied alternative to Monte Carlo Markov Chain methods.
Publisher: Springer Science and Business Media LLC
Date: 28-03-2002
DOI: 10.1007/S00439-002-0705-7
Abstract: The minimum physical distance surrounding a candidate gene has been determined in founder populations by studying allele sharing and then mapping historical recombination events. In this study, we developed a novel minimalistic approach by using the genetically isolated population of Tasmania, Australia, to identify candidate gene loci in a small number of in iduals of unknown genetic relationship affected by a dominant disorder. Keratoconus, an inheritable non-inflammatory progressive degeneration of the cornea, is present at a five-fold increased incidence in Burnie, a coastal town on the island of Tasmania. Based on the fundamental assumption that in iduals with keratoconus from this town are likely to be related through a founder effect, a 10-cM interval genome scan was conducted on six patients of undefined genetic relationship and one affected sib-pair to identify commonly shared chromosomal segments for the elucidation of candidate gene loci. Analysis of allele sharing revealed four markers on three chromosomes where all eight in iduals shared a common allele on at least one chromosome, and thirteen markers where all but one patient shared common alleles. No excess of allele sharing was observed at any marker tested on chromosome 21, a suggested candidate chromosome for keratoconus. Further analysis of positive loci revealed suggestive association at 20q12, where significant deviation in allele frequency D20S119 ( P=2.1 x 10(-5)) is observed when additional Tasmanian keratoconus s les are genotyped. Identification of a conserved minimal chromosomal haplotype around D20S119 in related Tasmanian patients suggests association with this locus, however association with the nearby candidate gene MMP-9 has been excluded.
Publisher: American Society of Hematology
Date: 09-2016
DOI: 10.1182/BLOOD-2015-09-666834
Abstract: AMPD3 activation reduces red blood cell half-life, which is associated with increased oxidative stress and phosphatidylserine exposure. AMPD3 activation causes malaria resistance through increased RBC turnover and increased RBC production.
Publisher: Springer Science and Business Media LLC
Date: 05-02-2004
Publisher: Elsevier BV
Date: 2000
Publisher: Public Library of Science (PLoS)
Date: 03-04-2014
Publisher: Springer Science and Business Media LLC
Date: 2008
DOI: 10.2165/00063030-200822040-00003
Abstract: Systemic lupus erythematosus (SLE) is a classic autoimmune disease characterized by a myriad of immune system aberrations, most likely resulting from pathogenic autoantibody production, immune complex deposition, and subsequent end-organ damage. B cells play a key role in the pathogenesis therefore, B-cell-targeted therapies, including B-cell depletion and blockage of B-cell survival factors such as B-lymphocyte stimulator (BLyS), are potential therapeutic targets for SLE. In uncontrolled clinical trials from approximately 20 studies, rituximab--a mouse-human chimeric anti-CD20 monoclonal antibody that effectively depletes B cells--has been demonstrated to reduce disease activity and decrease serum autoantibodies, with a clinical response of 86% in a case series of approximately 400 SLE patients with refractory disease, with or without concomitant use of cyclophosphamide. Epratuzumab, a humanized anti-CD22 monoclonal antibody that partially depletes B cells, has also been shown to reduce disease activity but not to decrease autoantibody levels in patients with moderately active SLE. Randomized controlled phase I/II trials in patients with active SLE have documented that belimumab, a humanized anti-BLyS monoclonal antibody, reduces B-cell numbers, inhibits disease activity and decreases anti-double-stranded DNA autoantibody in SLE patients. All these therapies are well tolerated, but accompanying infectious complications have been observed. Other B-cell-targeted therapies such as 'humanized' monoclonal antibodies to CD20 (e.g. ocrelizumab) and agents that interrupt B-cell/T-cell interactions also have potential, and the efficacy of these, along with rituximab, belimumab and epratuzumab, needs to be determined by randomized controlled trials.
Publisher: Wiley
Date: 10-2008
DOI: 10.1111/J.1528-1167.2008.01593.X
Abstract: Studies in animal models and patients have implicated changes in hyperpolarization-activated cyclic nucleotide-gated cation channel (HCN) expression in the pathogenesis of temporal lobe epilepsy (TLE). However, the nature of HCN changes during the epileptogenic process and their commonality across different TLE models is unknown. Here HCN1 and HCN2 mRNA expression was quantitatively measured at different time points during epileptogenesis in two distinct animal models of TLE the kainic acid (KA)-induced status epilepticus (SE) and amygdala kindling models. Hippoc al subregions (CA1, CA3, and dentate gyrus [DG]) and entorhinal cortex were dissected at different time-points. For KA-induced SE animals this was 24 h, 7 days (preepileptic), and 6 weeks (epileptic) post status. For amygdala kindling animals this was 2 weeks after reaching either "partially kindled" (one class II/III seizure) or "fully kindled" (five class V seizures) states. Quantification of regional hippoc al neuronal loss in the KA-treated animals was done using NeuN immunofluorescence and confocal microscopy. HCN mRNA levels decreased in an isoform and region specific manner at all time points after KA-induced SE. The decrease in neuronal number could not account for all reductions in HCN mRNA levels post-KA insult, implicating transcriptional changes. A reduction in HCN2 mRNA levels was also observed in fully kindled animals in the CA3 region. A reduction in HCN mRNA levels is present in two different models of TLE. This supports the case that a reduction in HCN channel expression is an accompaniment of epileptogenesis in different adult models of TLE.
Publisher: American Thoracic Society
Date: 08-2011
Publisher: American Association for Cancer Research (AACR)
Date: 07-2015
DOI: 10.1158/1055-9965.EPI-14-0317
Abstract: Background: Genome-wide association studies have identified multiple genetic variants associated with prostate cancer risk which explain a substantial proportion of familial relative risk. These variants can be used to stratify in iduals by their risk of prostate cancer. Methods: We genotyped 25 prostate cancer susceptibility loci in 40,414 in iduals and derived a polygenic risk score (PRS). We estimated empirical odds ratios (OR) for prostate cancer associated with different risk strata defined by PRS and derived age-specific absolute risks of developing prostate cancer by PRS stratum and family history. Results: The prostate cancer risk for men in the top 1% of the PRS distribution was 30.6 (95% CI, 16.4–57.3) fold compared with men in the bottom 1%, and 4.2 (95% CI, 3.2–5.5) fold compared with the median risk. The absolute risk of prostate cancer by age of 85 years was 65.8% for a man with family history in the top 1% of the PRS distribution, compared with 3.7% for a man in the bottom 1%. The PRS was only weakly correlated with serum PSA level (correlation = 0.09). Conclusions: Risk profiling can identify men at substantially increased or reduced risk of prostate cancer. The effect size, measured by OR per unit PRS, was higher in men at younger ages and in men with family history of prostate cancer. Incorporating additional newly identified loci into a PRS should improve the predictive value of risk profiles. Impact: We demonstrate that the risk profiling based on SNPs can identify men at substantially increased or reduced risk that could have useful implications for targeted prevention and screening programs. Cancer Epidemiol Biomarkers Prev 24(7) 1121–9. ©2015 AACR.
Publisher: Public Library of Science (PLoS)
Date: 08-02-2011
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-02-2009
Abstract: Platelets play a critical role in the pathogenesis of malarial infections by encouraging the sequestration of infected red blood cells within the cerebral vasculature. But platelets also have well-established roles in innate protection against microbial infections. We found that purified human platelets killed Plasmodium falciparum parasites cultured in red blood cells. Inhibition of platelet function by aspirin and other platelet inhibitors abrogated the lethal effect human platelets exert on P. falciparum parasites. Likewise, platelet-deficient and aspirin-treated mice were more susceptible to death during erythrocytic infection with Plasmodium chabaudi . Both mouse and human platelets bind malarial-infected red cells and kill the parasite within. These results indicate a protective function for platelets in the early stages of erythrocytic infection distinct from their role in cerebral malaria.
Publisher: Wiley
Date: 05-2000
DOI: 10.1046/J.1365-3024.2000.00305.X
Abstract: Infection of mice with Leishmania major has been used both as a model for the cutaneous disease in humans and as a model for the more general control and function of helper T cells in immunity. In both cases, disease patterns and disease progression have been assessed by two complementary methods, lesion size and parasite burden in the draining lymph nodes. We propose a much improved method for the graphical representation of lesion development which conveys more information with better accuracy. We also describe a polymerase chain reaction method for determining parasite burden, which is faster and allows the analysis of larger numbers of experimental animals than the current limiting dilution analysis. Moreover, these methods are equally applicable to other infectious diseases, an obvious one being schistosomiasis.
Publisher: Springer Science and Business Media LLC
Date: 10-2009
Publisher: American Society for Microbiology
Date: 11-2015
DOI: 10.1128/IAI.00926-15
Abstract: The treatment of iron deficiency in areas of high malaria transmission is complicated by evidence which suggests that iron deficiency anemia protects against malaria, while iron supplementation increases malaria risk. Iron deficiency anemia results in an array of pathologies, including reduced systemic iron bioavailability and abnormal erythrocyte physiology however, the mechanisms by which these pathologies influence malaria infection are not well defined. In the present study, the response to malaria infection was examined in a mutant mouse line, Tfrc MRI24910 , identified during an N -ethyl- N -nitrosourea (ENU) screen. This line carries a missense mutation in the gene for transferrin receptor 1 (TFR1). Heterozygous mice exhibited reduced erythrocyte volume and density, a phenotype consistent with dietary iron deficiency anemia. However, unlike the case in dietary deficiency, the erythrocyte half-life, mean corpuscular hemoglobin concentration, and intraerythrocytic ferritin content were unchanged. Systemic iron bioavailability was also unchanged, indicating that this mutation results in erythrocytic iron deficiency without significantly altering overall iron homeostasis. When infected with the rodent malaria parasite Plasmodium chabaudi adami , mice displayed increased parasitemia and succumbed to infection more quickly than their wild-type littermates. Transfusion of fluorescently labeled erythrocytes into malaria parasite-infected mice demonstrated an erythrocyte-autonomous enhanced survival of parasites within mutant erythrocytes. Together, these results indicate that TFR1 deficiency alters erythrocyte physiology in a way that is similar to dietary iron deficiency anemia, albeit to a lesser degree, and that this promotes intraerythrocytic parasite survival and an increased susceptibility to malaria in mice. These findings may have implications for the management of iron deficiency in the context of malaria.
Publisher: Cold Spring Harbor Laboratory
Date: 27-03-2019
DOI: 10.1101/589242
Abstract: An important component in host resistance to malaria infection are inherited mutations that give rise to abnormalities and deficiencies in erythrocyte proteins and enzymes. Understanding how such mutations confer protection against the disease may be useful for developing new treatment strategies. A mouse ENU-induced mutagenesis screen for novel malaria resistance-conferring mutations identified a novel nonsense mutation in the gene encoding porphobilinogen deaminase (PBGD) in mice, denoted here as Pbgd MRI58155 . Heterozygote Pbgd MRI58155 mice exhibited approximately 50% reduction in cellular PBGD activity in both mature erythrocytes and reticulocytes, although enzyme activity was approximately 10 times higher in reticulocytes than erythrocytes. When challenged with blood-stage P. chabaudi , which preferentially infects erythrocytes, heterozygote mice showed a modest but significant resistance to infection, including reduced parasite growth. A series of assays conducted to investigate the mechanism of resistance indicated that mutant erythrocyte invasion by P. chabaudi was normal, but that following intraerythrocytic establishment a significantly greater proportions of parasites died and therefore affected their ability to propagate. The Plasmodium resistance phenotype was not recapitulated in Pbgd -deficient mice infected with P. berghei , which prefers reticulocytes, or when P. falciparum was cultured in erythrocytes from patients with acute intermittent porphyria (AIP), which had modest (20-50%) reduced levels of PBGD. Furthermore, the growth of Pbgd -null P. falciparum and Pbgd -null P. berghei parasites, which grew at the same rate as their wild-type counterparts in normal cells, were not affected by the PBGD-deficient background of the AIP erythrocytes or Pbgd -deficient mice. Our results confirm the dispensability of parasite PBGD for P. berghei infection and intraerythrocytic growth of P. falciparum , but for the first time identify a requirement for host erythrocyte PBGD by P. chabaudi during in vivo blood stage infection. The causative agent of malaria, Plasmodium , adopts a parasitic lifestyle during erythrocyte infection, and as such relies on host cell factors for its survival and growth. Host-encoded mutations that alter the availability of these factors confer disease resistance, including several well-known genetic erythrocyte abnormalities that have arisen due to the historical evolutionary pressure of malaria. This study identified in mice a novel malaria resistance-conferring host mutation in the heme biosynthesis enzyme, porphobilinogen deaminase (PBGD), and compared the relative requirements by Plasmodium for the host versus parasite-encoded forms of PBGD in both in vivo and in vitro settings. The findings demonstrated that parasite PBGD was dispensable, but that the host enzyme was important specifically during in vivo infection by P. chabaudi , and collectively suggest that Plasmodium requires a certain threshold of the enzyme to sustain its intraerythrocytic growth. Plasmodium may therefore be vulnerable to other interventions that limit host PBGD activity.
Publisher: Elsevier BV
Date: 09-1998
Publisher: MyJove Corporation
Date: 05-04-2015
DOI: 10.3791/52736
Publisher: American Society for Microbiology
Date: 10-2006
DOI: 10.1128/IAI.01690-05
Abstract: Animals congenic for the char2 host response locus to the murine malarial parasite Plasmodium chabaudi have been bred, and they demonstrated a phenotypic difference from the parental lines. These congenic lines have been crossed back to the parental line to generate recombinants across the congenic intervals. The recombinants were inbred, and the subcongenic intervals were fixed. These lines were then challenged with parasites and assessed as being either resistant or susceptible. From the analysis of many subcongenic lines, it has become obvious that there are at least two loci underlying the char2 locus and that both of these mediate resistance when the haplotype derives from the resistant C57BL/6 strain.
Publisher: Informa UK Limited
Date: 2007
Publisher: American Society of Hematology
Date: 27-01-2011
DOI: 10.1182/BLOOD-2010-07-296475
Abstract: We describe a collection of 11 families with ≥ 2 generations of family members whose condition has been diagnosed as a hematologic malignancy. In 9 of these families there was a significant decrease in age at diagnosis in each subsequent generation (anticipation). The mean age at diagnosis in the first generation was 67.8 years, 57.1 years in the second, and 41.8 years in the third (P .0002). This was confirmed in both direct parent-offspring pairs with a mean reduction of 19 years in the age at diagnosis (P = .0087) and when the analysis was repeated only including cases of mature B-cell neoplasm (P = .0007). We believe that these families provide further insight into the nature of the underlying genetic mechanism of predisposition in these families.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 10-2005
DOI: 10.1167/IOVS.05-0312
Abstract: The purpose of this study was to identify genetic contributions to primary open-angle glaucoma (POAG) through investigations of two quantitative components of the POAG phenotype. Genome-wide multipoint variance-components linkage analyses of maximum recorded intraocular pressure (IOP) and maximum vertical cup-to-disc ratio were conducted on data from a single, large Australian POAG pedigree that has been found to segregate the myocilin Q368X mutation in some in iduals. Multipoint linkage analysis of maximum recorded IOP produced a peak LOD score of 3.3 (P = 0.00015) near marker D10S537 on 10q22, whereas the maximum cup-to-disc ratio produced a peak LOD score of 2.3 (P = 0.00056) near markers D1S197 to D1S220 on 1p32. Inclusion of the myocilin Q368X mutation as a covariate provided evidence of an interaction between this mutation and the IOP and cup-to-disc ratio loci. Significant linkage has been identified for maximum IOP and suggestive linkage for vertical cup-to-disc ratio. Identification of genes contributing to the variance of these traits will enhance understanding of the pathophysiology of POAG as a whole.
Publisher: Springer Science and Business Media LLC
Date: 07-1982
DOI: 10.1038/298090A0
Abstract: To assess how often older adults admitted to hospital for common non-cardiac conditions were discharged with intensified antihypertensive treatment, and to identify markers of appropriateness for these intensifications. Retrospective cohort study. US Veterans Administration Health System. Patients aged 65 years or over with hypertension admitted to hospital with non-cardiac conditions between 2011 and 2013. Intensification of antihypertensive treatment, defined as receiving a new or higher dose antihypertensive agent at discharge compared with drugs used before admission. Hierarchical logistic regression analyses were used to control for characteristics of patients and hospitals. Among 14 915 older adults (median age 76, interquartile range 69-84), 9636 (65%) had well controlled outpatient blood pressure before hospital admission. Overall, 2074 (14%) patients were discharged with intensified antihypertensive treatment, more than half of whom (1082) had well controlled blood pressure before admission. After adjustment for potential confounders, elevated inpatient blood pressure was strongly associated with being discharged on intensified antihypertensive regimens. Among patients with previously well controlled outpatient blood pressure, 8% (95% confidence interval 7% to 9%) of patients without elevated inpatient blood pressure, 24% (21% to 26%) of patients with moderately elevated inpatient blood pressure, and 40% (34% to 46%) of patients with severely elevated inpatient blood pressure were discharged with intensified antihypertensive regimens. No differences were seen in rates of intensification among patients least likely to benefit from tight blood pressure control (limited life expectancy, dementia, or metastatic malignancy), nor in those most likely to benefit (history of myocardial infarction, cerebrovascular disease, or renal disease). One in seven older adults admitted to hospital for common non-cardiac conditions were discharged with intensified antihypertensive treatment. More than half of intensifications occurred in patients with previously well controlled outpatient blood pressure. More attention is needed to reduce potentially harmful overtreatment of blood pressure as older adults transition from hospital to home.
Publisher: Emerald
Date: 16-11-2015
Abstract: – Networks and networking are ubiquitous concepts in tourism, their importance appreciated by scholars and practitioners. Tourism research has developed elaborate methods and concepts to grasp the numerous variants of tourism networks and to gain insights into their governance. In particular, Association Internationale D’Experts Scientifiques Du Tourisme (AIEST) and its official journal, Tourism Review , have made significant contributions to the achievements in this research area. After approximately two decades of intensive research on tourism networks, it is appropriate to pause for a moment to critically assess the results achieved, to compare them with partly old, partly newly, emerging real-world challenges, and to explore future directions. – This paper provides a selective and critical overview of the state-of-the-art in research on governing networks in tourism. This overview of eight major achievements is combined with an exploratory, comparative analysis of qualitative interviews with tourism practitioners. – Considering the two sources mentioned above, the study derives seven suggestions for future directions in research on network governance in tourism. These relate to the big picture of tourism governance, e-governance, disparities within networks, negative aspects of networking, dynamism of networks, network moderators and means of network steering. – Due to its design, the paper is uniquely able to compare real-world issues with up-to-date theoretical achievements, and will contribute to bringing them closer together in future approaches. Hence, it is relevant for both academic readers and practitioners.
Publisher: Society for Neuroscience
Date: 14-01-2009
DOI: 10.1523/JNEUROSCI.5295-08.2009
Abstract: Low-voltage-activated, or T-type, calcium (Ca 2+ ) channels are believed to play an essential role in the generation of absence seizures in the idiopathic generalized epilepsies (IGEs). We describe a homozygous, missense, single nucleotide (G to C) mutation in the Ca v 3.2 T-type Ca 2+ channel gene ( Cacna1h ) in the genetic absence epilepsy rats from Strasbourg (GAERS) model of IGE. The GAERS Ca v 3.2 mutation ( gcm ) produces an arginine to proline (R1584P) substitution in exon 24 of Cacna1h , encoding a portion of the III–IV linker region in Ca v 3.2. gcm segregates codominantly with the number of seizures and time in seizure activity in progeny of an F1 intercross. We have further identified two major thalamic Cacna1h splice variants, either with or without exon 25. gcm introduced into the splice variants acts “epistatically,” requiring the presence of exon 25 to produce significantly faster recovery from channel inactivation and greater charge transference during high-frequency bursts. This gain-of-function mutation, the first reported in the GAERS polygenic animal model, has a novel mechanism of action, being dependent on exonic splicing for its functional consequences to be expressed.
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.NBD.2008.04.012
Abstract: Stargazin is membrane bound protein involved in trafficking, synapse anchoring and biophysical modulation of AMPA receptors. A quantitative trait locus in chromosome 7 containing the stargazin gene has been identified as controlling the frequency and duration of absence seizures in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS). Furthermore, mutations in this gene result in the Stargazer mouse that displays an absence epilepsy phenotype. GAERS stargazin mRNA expression is increased 1.8 fold in the somatosensory cortex and by 1.3 fold in the thalamus. The changes were present before and after the onset of absence seizures indicating that increases are not a secondary consequence of the seizures. Stargazin protein expression was also significantly increased in the somatosensory cortex after the onset of spontaneous seizures. The results are of significant importance beyond the GAERS model, as they are the first to show that an increase in stargazin expression may be pro-epileptic.
Publisher: Elsevier
Date: 2005
Publisher: Oxford University Press (OUP)
Date: 09-0001
Abstract: Allelic heterogeneity is a common phenomenon where a gene exhibits a different phenotype depending on the nature of its genetic mutations. In the context of genes affecting malaria susceptibility, it allowed us to explore and understand the intricate host–parasite interactions during malaria infections. In this study, we described a gene encoding erythrocytic ankyrin-1 (Ank-1) which exhibits allelic-dependent heterogeneous phenotypes during malaria infections. We conducted an ENU mutagenesis screen on mice and identified two Ank-1 mutations, one resulting in an amino acid substitution (MRI95845), and the other a truncated Ank-1 protein (MRI96570). Both mutations caused hereditary spherocytosis-like phenotypes and confer differing protection against Plasmodium chabaudi infections. Upon further examination, the Ank-1(MRI96570) mutation was found to inhibit intraerythrocytic parasite maturation, whereas Ank-1(MRI95845) caused increased bystander erythrocyte clearance during infection. This is the first description of allelic heterogeneity in ankyrin-1 from the direct comparison between two Ank-1 mutations. Despite the lack of direct evidence from population studies, this data further supported the protective roles of ankyrin-1 mutations in conferring malaria protection. This study also emphasized the importance of such phenomena in achieving a better understanding of host–parasite interactions, which could be the basis of future studies.
Publisher: Public Library of Science (PLoS)
Date: 18-03-2016
Publisher: Oxford University Press (OUP)
Date: 2005
DOI: 10.1093/BFGP/4.3.270
Abstract: Leishmaniasis encompasses a number of disease syndromes, caused by several species of the digenetic protozoan Leishmania, and is transmitted by sandflies. The mouse model of the disease has been used to identify genes involved in disease susceptibility--for ex le, the Slc11a1 gene, important in resistance to Leishmania donovani--and to map loci important in Leishmania major infection. The genetics of the host response to L. major has been shown to be complex and to involve much more than the T helper cell response.
Publisher: Springer Science and Business Media LLC
Date: 28-03-2018
DOI: 10.1007/S00335-018-9744-9
Abstract: Malaria remains a deadly parasitic disease caused by Plasmodium, claiming almost half a million lives every year. While parasite genetics and biology are often the major targets in many studies, it is becoming more evident that host genetics plays a crucial role in the outcome of the infection. Similarly, Plasmodium infections in mice also rely heavily on the genetic background of the mice, and often correlate with observations in human studies, due to their high genetic homology with humans. As such, murine models of malaria are a useful tool for understanding host responses during Plasmodium infections, as well as dissecting host-parasite interactions through various genetic manipulation techniques. Reverse genetic approach such as quantitative trait loci studies and random mutagenesis screens have been employed to discover novel host genes that affect malaria susceptibility in mouse models, while other targeted studies utilize mouse models to validate observation from human studies. Herein, we review the findings from the past and present studies on murine models of hepatic and erythrocytic stages of malaria and speculate on how the current mouse models benefit from the recent development in CRISPR/Cas9 gene editing technology.
Publisher: Elsevier BV
Date: 12-1994
Abstract: As part of a larger effort to create a complete physical map of the human genome, we have developed 110 new STSs specific for human chromosome 22. Clones isolated and sequenced from chromosome 22-enriched libraries provided a source of primers. These STSs were localized to regions of chromosome 22 using a panel of somatic cell hybrids. In building a refined physical map of chromosome 22, this set of STSs should provide a substantial backbone.
Publisher: Elsevier BV
Date: 09-2000
DOI: 10.1086/303048
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-12-2012
Abstract: Activated platelets bound to malaria parasite–infected red blood cells were once thought to contribute to pathogenesis, but recently the platelets have been found to have a protective effect. McMorran et al. (p. 1348 see the Perspective by Engwerda and Good ) extended this discovery to show that platelet activation releases intracellular granules containing a chemokine, PF4, which is internalized by Plasmodium falciparum –infected red cells. Subsequently, mature parasites within the cells die. The Duffy blood-group factor on red blood cells is known to act as a nonspecific receptor for chemokines, such as PF4, as well as a receptor for cell invasion by other species of malaria parasite. When the Duffy antigen was blocked by antibody treatment, platelets and PF4 were less able to kill the P. falciparum parasites within.
Publisher: Wiley
Date: 19-09-2007
DOI: 10.1111/J.1365-3024.2007.00969.X
Abstract: In the conventional mouse model for cutaneous leishmaniasis involving infection with stationary phase Leishmania major promastigotes at the base of the tail, mice congenic for leishmaniasis resistance loci designated lmr1,2,3 cured their lesions more rapidly and laid down more ordered collagen fibres than the susceptible parental BALB/c mice, while the opposite was the case for the congenic mice carrying the susceptibility loci on the resistant C57BL/6 background. In that model, we showed that wound healing and not T cell responses played a major role in determining the resolution of skin infection. Here, we show a similar disease phenotype in the mouse model that mimics more closely the situation in humans, that is, strictly intradermal infection in the ear pinna with small numbers of metacyclic promastigotes. The data show that at the site of infection the innate and adaptive immune responses act in concert to clear parasites, and induce tissue repair and wound healing. Importantly, the data show that the host responses controlled by the lmr loci, which act locally to control infection in the skin, are distinct from the host responses operating systemically in the draining lymph node.
Publisher: American Society for Microbiology
Date: 08-2002
DOI: 10.1128/IAI.70.8.4750-4753.2002
Abstract: A major advance has been made towards the positional cloning of char2 (a quantitative trait locus encoding resistance to Plasmodium chabaudi malaria). Mice congenic for the locus have been used to fine map the gene and to prove that char2 plays a significant role in the outcome of malarial infection, independently of other resistance loci.
Publisher: Springer Science and Business Media LLC
Date: 17-03-2014
Publisher: Elsevier BV
Date: 02-2002
DOI: 10.1016/S0042-6989(01)00232-2
Abstract: We used the chemical mutagen, N-ethyl-N-nitrosourea, to induce random point mutations in the germline of the mouse strain C57BL/6 in order to generate models of retinal diseases. 1163 mutagenised first generation mice produced using this approach were examined for eye abnormalities. Approximately one-third (412) presented with some form of ocular abnormality. Most changes were unilateral and confined to the anterior segment of the eye. Less than 10% (44) of identified changes affected the posterior segment of the eye. 21 mice with varying ocular abnormalities, including 17 with retinal changes, were bred to produce second generation mice to confirm genetic inheritance. Genetic inheritance was confirmed in several of these lines including three with retinal changes.
Publisher: Oxford University Press (OUP)
Date: 2005
DOI: 10.1093/BFGP/4.3.214
Abstract: Malaria and trypanosomiasis are vector-borne protozoal diseases which disproportionately affect the poor. Both give rise to immense human suffering malaria exerts its effect directly on human health, while trypanosomiasis causes damage largely though its effect on the health and productivity of the livestock on which so many poor people depend. These diseases both have multifaceted and poorly understood mechanisms of pathogenesis, combined with relatively complex life cycles characterised by multiple stages in both insect vector and mammalian host. In both cases, there is a dramatic effect of host genotype on disease progression. This effect is apparent in both the human and cattle hosts and among inbred mouse strains. This provides an opportunity to use the mouse to probe the mechanisms underlying resistance or susceptibility to pathology. The availability of high-density linkage maps, the genome sequence and transcriptomics tools has transformed the power of the mouse to illuminate such fundamental aspects of the host--parasite interaction.
Publisher: Wiley
Date: 02-2010
DOI: 10.1002/ANA.21849
Publisher: Elsevier BV
Date: 30-05-2008
Publisher: Springer Science and Business Media LLC
Date: 23-03-2004
Publisher: Springer Science and Business Media LLC
Date: 08-2000
Abstract: Poor resolution, retarded progress of DNA through gels, and variable sizing of DNA fragments between and within gels hinder accurate genotyping of some simple sequence length polymorphism (SSLP) markers with the Perkin Elmer Applied Biosystems 377 Sequenator. These problems are similar to renaturation related problems observed in DNA sequencing gels. PCR products especially susceptible to these problems are shown to have higher melting temperatures (T(m)) than others. Gels containing increased concentrations of denaturants allow greater accuracy in allelic discrimination. This is especially beneficial where quantification is necessary.
Publisher: Public Library of Science (PLoS)
Date: 19-06-2012
Publisher: BMJ
Date: 07-05-2011
Abstract: Genetic susceptibility to multiple sclerosis (MS) has been recognised for many years. Considerable data exist from the northern hemisphere regarding the familial recurrence risks for MS, but there are few data for the southern hemisphere and regions at lower latitude such as Australia. To investigate the interaction between environmental and genetic causative factors in MS, the authors undertook a familial recurrence risk study in three latitudinally distinct regions of Australia. Immediate and extended family pedigrees have been collected for three cohorts of people with MS in Queensland, Victoria and Tasmania spanning 15° of latitude. Age of onset data from Queensland were utilised to estimate age-adjusted recurrence rates. Recurrence risks in Australia were significantly lower than in studies from northern hemisphere populations. The age-adjusted risk for siblings across Australia was 2.13% compared with 3.5% for the northern hemisphere. A similar pattern was seen for other relatives. The risks to relatives were proportional to the population risks for each site, and hence the sibling recurrence-risk ratio (λ(s)) was similar across all sites. The familial recurrence risk of MS in Australia is lower than in previously reported studies. This is directly related to the lower population prevalence of MS. The overall genetic susceptibility in Australia as measured by the λ(s) is similar to the northern hemisphere, suggesting that the difference in population risk is explained largely by environmental factors rather than by genetic admixture.
Publisher: Springer Science and Business Media LLC
Date: 08-2011
DOI: 10.1038/NATURE10251
Publisher: Elsevier BV
Date: 08-2009
Abstract: Leishmaniasis is one of the world's important infectious diseases. It is prevalent in tropical and subtropical regions of the world and endemic in 88 countries, with two million new cases of leishmaniasis reported annually. As a complex disease, the pathology of leishmaniasis varies and is determined by factors such as the environment, the insect vector, and parasite and host genetics. The contributing host genetics involve multiple genes thus, the mouse model of leishmaniasis has been exploited extensively in an attempt to identify and dissect the contribution of disease modifier genes to pathogenesis. This review summarizes recent advances in the identification of genetic loci involved in the host response to Leishmania spp. in the mouse model and in the human situation.
Location: United States of America
Location: Australia
Start Date: 2008
End Date: 12-2008
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2012
End Date: 12-2014
Amount: $280,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2008
End Date: 03-2011
Amount: $400,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 09-2013
End Date: 09-2016
Amount: $427,510.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2007
End Date: 12-2007
Amount: $570,000.00
Funder: Australian Research Council
View Funded Activity