ORCID Profile
0000-0002-3303-9134
Current Organisation
University of Otago
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Publisher: Cambridge University Press (CUP)
Date: 18-11-2020
DOI: 10.1017/S0022149X19000981
Abstract: The superfamily Pronocephaloidea Looss, 1899 comprises digeneans occurring in the gut and respiratory organs of fishes, turtles, marine iguanas, birds and mammals. Although many life cycles are known for species of the Notocotylidae Lühe, 1909 maturing in birds and mammals, relatively few are known for the remaining pronocephaloid lineages. We report the cercariae of five pronocephaloid species from marine gastropods of the Queensland coast, Australia. From Lizard Island, northern Great Barrier Reef, we report three cercariae, two from Rhinoclavis vertagus (Cerithiidae) and one from Nassarius coronatus (Nassariidae). From Moreton Bay, southern Queensland, an additional two cercariae are reported from two genotypes of the gastropod worm shell Thylacodes sp. (Vermetidae). Phylogenetic analysis using 28S rRNA gene sequences shows all five species are nested within the Pronocephaloidea, but not matching or particularly close to any previously sequenced taxon. In combination, phylogenetic and ecological evidence suggests that most of these species will prove to be pronocephalids parasitic in marine turtles. The Vermetidae is a new host family for the Pronocephaloidea.
Publisher: Cold Spring Harbor Laboratory
Date: 20-11-2022
DOI: 10.1101/2022.11.18.517140
Abstract: Epilepsy, a clinical diagnosis characterized by paroxysmal episodes known as seizures, affects 1% of people worldwide. Safe and patient-specific treatment is vital and can be achieved by the development of rapid pre-clinical models of for identified epilepsy genes. Epilepsy can result from either brain injury or gene mutations, and can also be induced chemically. Xenopus laevis tadpoles could be a useful model for confirmation of variants of unknown significance found in epilepsy patients, and for drug re-purposing screens that could eventually lead to benefits for patients. Here, we characterise and quantify seizure-related behaviours in X. laevis tadpoles arrayed in 24-well plates. To provoke acute seizure behaviours, tadpoles were chemically induced with either pentylenetetrazole (PTZ) or 4-aminopyridine (4-AP). To test the capacity to adapt this method for drug testing, we also exposed induced tadpoles to the anti-seizure drug valproate (VPA). Four induced seizure-like behaviours were described and manually quantified, and two of these (darting, circling) could be accurately detected automatically, using the video analysis software TopScan. Additionally, we recorded swimming trajectories and mean swimming velocity. Automatic detection showed that either PTZ or 4-AP induced darting behaviour and increased mean swimming velocity compared to untreated controls. Both parameters were significantly reduced in the presence of VPA. In particular, darting behaviour was a shown to be a sensitive measure of epileptic seizure activity. While we could not automatically detect the full range of seizure behaviours, this method shows promise for future studies, since X. laevis is a well-characterised and genetically tractable model organism.
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.IJPARA.2016.11.002
Abstract: Blood flukes of the family Spirorchiidae are significant pathogens of both free-ranging and captive marine turtles. Despite a significant proportion of marine turtle mortality being attributable to spirorchiid infections, details of their life cycles remain almost entirely unknown. Here we report on the molecular elucidation of the complete life cycle of a marine spirorchiid, identified as Amphiorchis sp., infecting vermetid gastropods and captive hatched neonate Caretta caretta in the Oceanogràfic Aquarium, in Valencia, Spain. Specimens of a vermetid gastropod, Thylaeodus cf. rugulosus (Monterosato, 1878), collected from the aquarium filtration system housing diseased C. caretta, were infected with sporocysts and cercariae consistent with the family Spirorchiidae. We generated rDNA sequence data [internal transcribed spacer 2 (ITS2) and partial 28S rDNA] from infections from the vermetid which were identical to sequences generated from eggs from the serosa of the intestine of neonate C. caretta, and an adult spirorchiid from the liver of a C. caretta from Florida, USA. Given the reliability of these markers in the delineation of trematode species, we consider all three stages to represent the same species and tentatively identify it as a species of Amphiorchis Price, 1934. The source of infection at the Oceanogràfic Foundation Rehabilitation Centre, Valencia, Spain, is inferred to be an adult C. caretta from the western Mediterranean being rehabilitated in the same facility. Phylogenetic analysis suggests that this Amphiorchis sp. is closely related to other spirorchiids of marine turtles (species of Carettacola Manter & Larson, 1950, Hapalotrema Looss, 1899 and Learedius Price, 1934). We discuss implications of the present findings for the control of spirorchiidiasis in captivity, for the better understanding of epidemiology in wild in iduals, and the elucidation of further life cycles.
Publisher: Public Library of Science (PLoS)
Date: 31-08-2016
Publisher: Wiley
Date: 25-02-2012
DOI: 10.1111/WRR.13003
Abstract: Xenopus laevis tadpoles can regenerate functional tails, containing the spinal cord, notochord, muscle, fin, blood vessels and nerves, except for a brief refractory period at around 1 week of age. At this stage, utation of the tadpole's tail may either result in scarless wound healing or the activation of a regeneration programme, which replaces the lost tissues. We recently demonstrated a link between bacterial lipopolysaccharides and successful tail regeneration in refractory stage tadpoles and proposed that this could result from lipopolysaccharides binding to Toll‐like receptor 4 (TLR4). Here, we have used 16S rRNA sequencing to show that the tadpole skin microbiome is highly variable between sibships and that the community can be altered by raising embryos in the antibiotic gentamicin. Six Gram‐negative genera, including Delftia and Chryseobacterium , were over‐represented in tadpoles that underwent tail regeneration. Lipopolysaccharides purified from a commensal Chryseobacterium spp. XDS4 , an exogenous Delftia spp . or Escherichia coli , could significantly increase the number of antibiotic‐raised tadpoles that attempted regeneration. Conversely, the quality of regeneration was impaired in native‐raised tadpoles exposed to the antagonistic lipopolysaccharide of Rhodobacter sphaeroides . Editing TLR4 using CRISPR/Cas9 also reduced regeneration quality, but not quantity, at the level of the cohort. However, we found that the editing level of in idual tadpoles was a poor predictor of regenerative outcome. In conclusion, our results suggest that variable regeneration in refractory stage tadpoles depends at least in part on the skin microbiome and lipopolysaccharide signalling, but that signalling via TLR4 cannot account for all of this effect.
Publisher: Frontiers Media SA
Date: 22-10-2019
Publisher: Springer Science and Business Media LLC
Date: 2015
DOI: 10.1007/S11230-014-9535-Y
Abstract: Adult blood flukes of the genera Hapalotrema Looss, 1899 and Learedius Price, 1934 were collected from turtles off Queensland and the Hawaiian Islands. Specimens were identified as Hapalotrema pambanensis Mehrotra, 1973, H. synorchis Luhman, 1935, H. postorchis Rao, 1976 and Learedius learedi Price, 1934 on the basis of morphology. No major morphological differences were found between specimens from this study and previously published descriptions. DNA was also extracted and sequences obtained using custom spirorchiid-specific primers for the ITS2 and 28S rDNA regions, in order to confirm species identification and investigate phylogenetic relationships. Intraspecific genetic variation was generally low. However the ITS2 region of H. postorchis and to a lesser extent that of L. learedi showed considerable variation between specimens from the Pacific and Atlantic oceans. Further studies will be required to determine whether this variation should be considered inter- or intra-specific. Maximum likelihood phylogenetic analyses were completed for both sequenced genes. Learedius learedi was unequivocally nested among species of Hapalotrema, suggesting that the status of the genus Learedius may need to be reassessed.
Publisher: American Society of Parasitologists
Date: 12-2017
DOI: 10.1645/16-31
Abstract: Neospirorchis (Digenea: "Spirorchiidae") are blood flukes of sea turtles. Trematodes tentatively identified as Neospirorchis sp. infect various sites within sea turtles inhabiting waters of the southeastern United States, but efforts to obtain specimens adequate for morphologic study has proven difficult. Two genetic targets, the internal transcribed spacer region of the ribosomal RNA gene and the partial mitochondrial cytochrome c oxidase subunit I gene, were used to investigate potential ersity among parasite specimens collected from stranded sea turtles. Sequence data were obtained from 215 trematode and egg specimens collected from 92 in idual free-ranging cheloniid sea turtles comprising 4 host species. Molecular analysis yielded more than 20 different genotypes. We were able to assign 1 genotype to 1 of the 2 recognized species, Neospirorchis pricei Manter and Larson, 1950 . In many ex les, genotypes exhibited host and site specificity. Our findings indicate considerable ersity of parasites resembling Neospirorchis with evidence of a number of uncharacterized blood flukes that require additional study.
Publisher: Wiley
Date: 17-05-2023
DOI: 10.1111/JNC.15836
Abstract: Epilepsy, a clinical diagnosis characterised by paroxysmal episodes known as seizures, affects 1% of people worldwide. Safe and patient‐specific treatment is vital and can be achieved by the development of rapid pre‐clinical models of for identified epilepsy genes. Epilepsy can result from either brain injury or gene mutations, and can also be induced chemically. Xenopus laevis tadpoles could be a useful model for confirmation of variants of unknown significance found in epilepsy patients, and for drug re‐purposing screens that could eventually lead to benefits for patients. Here, we characterise and quantify seizure‐related behaviours in X. laevis tadpoles arrayed in 24‐well plates. To provoke acute seizure behaviours, tadpoles were chemically induced with either pentylenetetrazole (PTZ) or 4‐aminopyridine (4‐AP). To test the capacity to adapt this method for drug testing, we also exposed induced tadpoles to the anti‐seizure drug valproate (VPA). Four induced seizure‐like behaviours were described and manually quantified, and two of these (darting, circling) could be accurately detected automatically, using the video analysis software TopScan. Additionally, we recorded swimming trajectories and mean swimming velocity. Automatic detection showed that either PTZ or 4‐AP induced darting behaviour and increased mean swimming velocity compared to untreated controls. Both parameters were significantly reduced in the presence of VPA. In particular, darting behaviour was a shown to be a sensitive measure of epileptic seizure activity. While we could not automatically detect the full range of seizure behaviours, this method shows promise for future studies since X. laevis is a well‐characterised and genetically tractable model organism. image
Publisher: Cold Spring Harbor Laboratory
Date: 10-12-2021
DOI: 10.1101/2021.12.09.472019
Abstract: Xenopus laevis tadpoles can regenerate functional tails, containing spinal cord, notochord, muscle, fin, blood vessels and nerves, except for a brief refractory period at around one week of age. At this stage, utation of the tadpole’s tail may either result in scarless wound healing, or the activation of a regeneration programme, which replaces the lost tissues. We recently demonstrated a link between bacterial lipopolysaccharides and successful tail regeneration in refractory stage tadpoles, and proposed that this could result from lipopolysaccharides binding to Toll-like receptor 4 (TLR4). Here, we have used 16S rRNA sequencing to show that the tadpole skin microbiome is highly variable between sibships and that the community can be altered by raising embryos in the antibiotic gentamicin. Six gram-negative genera, including Delftia and Chryseobacterium , were over-represented in tadpoles that underwent tail regeneration. Lipopolysaccharides purified from a commensal Chryseobacterium spp. XDS4 , an exogenous Delftia spp . or Escherichia coli could significantly increase the number of antibiotic-raised tadpoles that attempted regeneration. Conversely, the quality of regeneration was impaired in native-raised tadpoles exposed to the antagonistic lipopolysaccharide of Rhodobacter sphaeroides . Editing TLR4 using CRISPR/Cas9 also reduced regeneration quality, but not quantity, at the level of the cohort. However, we found that the editing level of in idual tadpoles was a poor predictor of regenerative outcome. In conclusion, our results suggest that variable regeneration in refractory stage tadpoles depends at least in part on the skin microbiome and lipopolysaccharide signalling, but that signalling via TLR4 cannot account for all of this effect.
Publisher: Public Library of Science (PLoS)
Date: 23-03-2016
Publisher: Inter-Research Science Center
Date: 28-03-2019
DOI: 10.3354/DAO03348
Abstract: Blood flukes of the family Spirorchiidae are important disease agents in marine turtles. The family is near cosmopolitan in distribution. Twenty-nine marine species across 10 genera are currently recognized, but taxonomic problems remain and it is likely that more species will be discovered. Spirorchiids infect the circulatory system, where they and their eggs cause a range of inflammatory lesions. Infection is sometimes implicated in the death of the turtle. In some regions, prevalence in stranded turtles is close to 100%. Knowledge of life cycles, important for control and epidemiological studies, has proven elusive until recently, when the first intermediate host identifications were made. Recent molecular studies of eggs and adult worms indicate that a considerable level of intrageneric and intraspecific ersity exists. The characterization of this ersity is likely to be of importance in exploring parasite taxonomy and ecology, unravelling life cycles, identifying the differential pathogenicity of genotypes and species, and developing antemortem diagnostic tools, all of which are major priorities for future spirorchiid research. Diagnosis to date has been reliant on copromicroscopy or necropsy, which both have significant limitations. The current lack of reliable antemortem diagnostic options is a roadblock to determining the true prevalence and epidemiology of spirorchiidiasis and the development of effective treatment regimes.
Publisher: Wildlife Disease Association
Date: 31-03-2020
DOI: 10.7589/2019-05-115
Abstract: An epizootic of coccidiosis in free-ranging green turtles (
Publisher: Wiley
Date: 15-11-2006
Publisher: Elsevier BV
Date: 04-2017
Publisher: Public Library of Science (PLoS)
Date: 22-02-2016
Publisher: American Society for Microbiology
Date: 16-12-2021
DOI: 10.1128/MRA.01050-21
Abstract: Here, we report the genome sequences of three bacterial isolates, Kinneretia sp. strain XES5, Shinella sp. strain XGS7, and Vogesella sp. strain XCS3, which were cultured from skin of adult female laboratory-bred Xenopus laevis .
Publisher: Cold Spring Harbor Laboratory
Date: 06-10-2023
No related grants have been discovered for Phoebe A Chapman.