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Christopher M Austin - One of the best experts on this subject based on the ideXlab platform.
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The complete mitogenome of the endangered freshwater crayfish Cherax tenuimanus (Smith 1912) (Crustacea: Decapoda: Parastacidae).
Mitochondrial DNA. Part A DNA mapping sequencing and analysis, 2015Co-Authors: Christopher M Austin, Mun Hua Tan, Huan You Gan, Han Ming GanAbstract:Next-Gen sequencing was used to recover the complete mitochondrial genome of Cherax tenuimanus. The mitogenome consists of 15,797 base pairs (68.14% A + T content) containing 13 protein-coding genes, two ribosomal subunit genes, 22 transfer RNAs, and a 779 bp non-coding AT-rich region. Mitogenomes have now been recovered for all six species of Cherax native to Western Australia.
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The complete mitogenome of the crayfish Cherax glaber (Crustacea: Decapoda: Parastacidae)
Mitochondrial DNA. Part A DNA mapping sequencing and analysis, 2014Co-Authors: Christopher M Austin, Mun Hua Tan, Laurence J. Croft, Han Ming GanAbstract:The complete mitochondrial genome of Cherax glaber was sequenced using the HiSeq platform. The mitogenome consists of 15,806 base pairs containing 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs and a non-coding AT-rich region. The Cherax glaber has a base composition of 32.39% for T, 22.42% for C, 33.73% for A and 11.46% for G, with an AT bias of 66.12%.
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Molecular phylogeny and zoogeography of the freshwater crayfish genus Cherax Erichson (Decapoda: Parastacidae) in Australia
Biological Journal of the Linnean Society, 2004Co-Authors: D. H. N. Munasinghe, Christopher P. Burridge, Christopher M AustinAbstract:The evolutionary history and biogeography of freshwater-dependent taxa in Australia is of intrinsic interest given the present-day aridity of this continent. Cherax is the most widespread and one of the most species-rich of Australia's nine freshwater crayfish genera. The phylogenetic relationships amongst 19 of the 23 Australian Cherax were established from mitochondrial DNA sequences representing the 12S rRNA and 16S rRNA gene regions. The relationships among species support an initial east–west separation, followed by a north–south divergence in eastern Australia. Molecular clock estimations suggest that these divergences date back to the Miocene. The phylogenetic relationships support endemic speciation within geographical regions and indicate that long-distance dispersal has not led to recent speciation as previously hypothesized. This new evolutionary scenario is consistent with the climatic history of Australia and the evolutionary history of other similarly distributed freshwater-dependent organisms in Australia.
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The systematics of freshwater crayfish of the genus Cherax Erichson (Decapoda : Parastacidae) in eastern Australia re-examined using nucleotide sequences from 12S rRNA and 16S rRNA genes
Invertebrate Systematics, 2004Co-Authors: D. H. N. Munasinghe, Christopher P. Burridge, Christopher M AustinAbstract:Nucleotide sequence data were used to re-examine systematic relationships and species boundaries within the genus Cherax from eastern Australia. Partial sequences were amplified from the 12S (~365 bp) and 16S (~545 bp) rRNA mitochondrial gene regions. Levels of intra- and inter-specific divergence for Cherax species were very similar between the two gene regions and similar to that reported for other freshwater crayfish for 16S rRNA. Phylogenetic analyses using the combined data provided strong support for a monophyletic group containing 11 eastern Australian species and comprising three well-defined species-groups: the ' C. destructor ' group containing three species, the ' C. cairnsensis ' group containing four species and the ' C. cuspidatus ' group containing two species. Cherax dispar and C. robustus are distinct from all other species and each other. In addition, two northern Australian and a New Guinean species were placed in the ' Astaconephrops ' group, which is the sister- group to the eastern Australian Cherax lineage. Several relationships were clarified, including: the status of northern and southern C. cuspidatus as separate species; a close relationship between C. cairnsensis and C. depressus ; the validity of C. rotundus and C. setosus as separate species and their close affinities with C. destructor ; and the distinctiveness of the northern forms of Cherax . The analysis of the 12S rRNA and 16S rRNA data is highly concordant with the results of previous allozyme studies.
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The taxonomy and phylogeny of the Cherax destructor complex (Decapoda : Parastacidae) examined using mitochondrial 16S sequences
Australian Journal of Zoology, 2003Co-Authors: Christopher M Austin, Maliwan Meewan, Trang Thi Thuy Nguyen, Dean R. JerryAbstract:This study uses nucleotide sequences from the 16S rRNA mitochondrial gene to investigate the taxonomy and phylogeny of freshwater crayfish belonging to the 'Cherax destructor' complex. The sequencing of an approximately 440-bp fragment of this gene region from freshwater crayfish sampled from 14 locations identified significant haplotype diversity. Phylogenetic analysis found three distinct clades that correspond to the species C. rotundus, C. setosus and C. destructor. C. rotundus is largely confined to Victoria, and C. setosus is restricted to coastal areas north of Newcastle in New South Wales. C. destructor is widely distributed in eastern Australia and shows significant phylogeographic structure, with three well supported clades. None of these clades, however, correspond to species previously recognised as C. esculus, C. davisi or C. albidus. The failure to genetically distinguish these morphologically defined species is consistent with reproductive information and morphological plasticity relating to habitat similar to that documented for other Cherax species.
Leigh Owens - One of the best experts on this subject based on the ideXlab platform.
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Natural, in ovo, vertical transmission of the RNA viruses, Chequa iflavirus and Athtab bunyavirus, but not Cherax reovirus in redclaw crayfish (Cherax quadricarinatus)
Aquaculture, 2021Co-Authors: Wansadaj Jaroenram, Leigh Owens, Orachun Hayakijkosol, Jennifer EllimanAbstract:Abstract The first molecular evidence for natural, in ovo, vertical transmission of Chequa iflavirus and Athtab bunyavirus from farmed female redclaw crayfish (Cherax quadricarinatus) cultured in northern Queensland, Australia is presented. Cherax reovirus was also examined, but evidence that this is spread via in ovo vertically transmission is very limited. Amongst 57 broodstock-derived pools of fertilized eggs, 38 (66.7%), 34 (59.6%) and 6 (10.5%) were positive for Chequa iflavirus, Athtab bunyavirus and Cherax reovirus respectively with the respective average loads of 6.56 × 104, 2.33 × 103 and 1.03 × 101 copies/μl of tested samples. Grouping samples by farm origins, all viruses in most farms were statistically similar (P > 0.05) for viral loads. As two viruses are transovarial transmitted, surface sterilizing practices would be ineffective and the load remains high as is seen in Chequa iflavirus and Athtab bunyavirus, but extremely low on surface-treated eggs as appears with Cherax reovirus. Our evidence, plus the literature, supports the general rule that if the virus is in the gut, most of the vertical transmission is faecal /oral and can be drastically reduced by efficient egg surface sterilization. If the virus is spread in ovo, then RT-qPCR testing coupled with therapeutic methods and selection of resistant crayfish families or detection of viral negative, geographically isolated populations of crayfish is the way forward for the removal of Chequa iflavirus and Athtab bunyavirus.
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Reverse transcription polymerase chain reaction (RT-PCR) detection for Australian Cherax reovirus from redclaw crayfish (Cherax quadricarinatus)
Aquaculture, 2021Co-Authors: Orachun Hayakijkosol, Leigh Owens, Wansadaj Jaroenram, Jennifer EllimanAbstract:Reoviruses have been isolated from many aquatic animals including fish and crustaceans. Viral inclusion bodies of reovirus have been found in the cytoplasm of the hepatopancreatic cells of redclaw crayfish (Cherax quadricarinatus). In the past, reverse transcription polymerase chain reaction (RT-PCR) designed from across other hosts was attempted to detect reovirus in redclaw crayfish but no specific set of primers successfully identified infected crayfish. In this study, two new sets of primers (Reo35F - Reo585R and Reo35F - Seq.R1) producing a 551 bp product and a 1370 bp product respectively were designed using C. quadricarinatus reovirus partial sequence (NCBI GenBank accession no. KM405245). After the removal of primer sequences, the smaller PCR product was a 99.21% match to KM405245 while the larger product was a 99.32% match. Only three amino acid differences were observed between the Australian and Chinese sequences. The Australian sequence is the ancestral sequence so changes are reported in that order: i.e. Australian>Chinese: 19Arg>Lys; 363Leu>Met; 423Gly>Asp. The longer Australian Cherax reovirus sequence inclusive of primer sequence has been submitted to NCBI GenBank number MN308286. The second set of primers was used in the world's first RT-PCR diagnostic method to detect the Australian reovirus from redclaw crayfish. The method has the detection limit of 1000 reovirus genome equivalents, and showed no cross-reactions with other prawn pathogens indicating its high sensitivity and specificity for Cherax reovirus diagnosis.
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First complete genome of an Ambidensovirus; Cherax quadricarinatus densovirus, from freshwater crayfish Cherax quadricarinatus.
Marine Genomics, 2015Co-Authors: Shaun Bochow, Kelly Condon, Jennifer Elliman, Leigh OwensAbstract:Abstract In 1999, the causative agent of an epizootic in Cherax quadricarinatus was described, and given the provisional name Cherax quadricarinatus parvovirus-like. Sequencing of the 6334 nt genome identified three open-reading frames on the top strand coding NS3 (35.55 kDa), NS1 (67.36 kDa) and NS2 (35.18 kDa) and on the bottom strand a single open reading frame which most likely encodes 4 structural proteins. Motifs characteristic of the Densovirinae were found in the ORFs. Phylogenetic analysis of the amino acids in NS1 places the genome in the genus Ambidensovirus, most closely related to the marine sea star densovirus (75%, E = 0.0) and distantly related to Acheta domestica densovirus (44.1%). The virus name is proposed as species Decapod ambidensovirus, variant Cherax quadricarinatus densovirus. This is the first Ambidensovirus to be found in decapod crustaceans and the first of the subfamily Densovirinae to be sequenced from a freshwater crayfish. Cherax quadricarinatus densovirus and sea star densovirus are the first highly related Densovirinae to infect phylogenetically disparate hosts and are thus far, unique among the Densovirinae.
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Age at first infection of Cherax quadricarinatus by Cherax quadricarinatus bacilliform virus and Cherax Giardiavirus-like virus, and production of putative virus-free crayfish
Aquaculture, 1997Co-Authors: Brett F. Edgerton, Leigh OwensAbstract:Abstract This study determined the age at which Cherax quadricarinatus is first susceptible to infection by Cherax quadricarinatus bacilliform virus (CqBV) and Cherax Giardiavirus -like virus (CGV). The first CqBV infected juvenile was diagnosed 2 weeks after the juvenile moulted into stage 3 (week 2), and the prevalence of CqBV rose steadily to 17.1% at the completion of the experiment (week 7). CGV was first diagnosed at week 1 and its prevalence rose dramatically to reach 58% by week 3 and 86% by week 6. Presumptive virus-free juvenile C. quadricarinatus were produced from infected females by removing the eggs at the eyed stage, sterilising and hatching them, and culturing the juveniles in uncontaminated water. These procedures may be used to prevent CqBV and CGV infections in aquaculture, or more importantly, prevent translocations of these viruses.
Antonin Kouba - One of the best experts on this subject based on the ideXlab platform.
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Cherax acherontis (Decapoda: Parastacidae), the first cave crayfish from the Southern Hemisphere (Papua Province, Indonesia).
Zootaxa, 2017Co-Authors: Jiří Patoka, Martin Bláha, Antonin KoubaAbstract:Cherax acherontis n. sp., is a crayfish endemic to the submerged river Yumugima in Hagepma/Jugurama cave in the New Guinea Highlands, Jayawijaya Regency, Papua Province, Indonesia. This species is the first cave crayfish from the Southern Hemisphere. The new species is most similar to Cherax monticola . Both species can be easily distinguished by certain morphological characteristics, which easily demonstrate C. acherontis n. sp. is a valid species.
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Cherax (Cherax) Subterigneus, A New Crayfish (Decapoda: Parastacidae) from West Papua, Indonesia
Journal of Crustacean Biology, 2015Co-Authors: Jiří Patoka, Martin Bláha, Antonin KoubaAbstract:Cherax ( Cherax ) subterigneus n. sp., is a crayfish endemic to the Aitinjo Lake of West Papua, Indonesia. This species is one of the field-captured species from this region that are exploited for ornamental purposes. Its commonly used commercial name in the pet trade is “Black Orange Tip Crayfish,” “Orange Tip Crayfish,” or “Red Tip Crayfish.” The new species is genetically and morphologically similar to Cherax holthuisi , however, both species can be easily distinguished by certain morphological characteristics or by using sequence divergence, which is substantial, for considering C. subterigneus n. sp. as a valid species. We have also added a note about the probable incorrect subgeneric assignment of the Cherax peknyi and mandatory change of incorrect original spelling of recently described C. gherardii as C. gherardiae .
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Cherax (Astaconephrops) gherardii, a new crayfish (Decapoda: Parastacidae) from West Papua, Indonesia.
Zootaxa, 2015Co-Authors: Jiří Patoka, Martin Bláha, Antonin KoubaAbstract:Cherax ( Astaconephrops ) gherardii n. sp. is a moderate burrowing crayfish endemic to the Ajamaru Lakes of West Papua, Indonesia. This species is one of the crayfish species from this region that are exploited for ornamental purposes. Its commonly used commercial name in the pet trade is “Rainbow Crayfish” or “Blue Moon Crayfish”, and its native name is “udang kuku biru”. The new species is genetically and morphologically similar to Cherax boesemani , however, both species may be easily distinguished morphologically or by using sequence divergence, which is substantial for considering C. gherardii n. sp. to be a valid species.
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comparative ultrastructure of spermatozoa of the redclaw Cherax quadricarinatus and the yabby Cherax destructor decapoda parastacidae
Micron, 2015Co-Authors: Antonin Kouba, Hamid Niksirat, Martin BláhaAbstract:Abstract Ultrastructure of spermatozoa of redclaw Cherax quadricarinatus and yabby Cherax destructor were described and compared. The acrosome complex and nucleus are located at the anterior and posterior region of the spermatozoon, respectively. The acrosome is a complex vesicle divided into two parts: the main body of the acrosome appears as a dense cup-shaped structure in longitudinal sagittal view, with the subacrosome zone occupying the central area of the vesicle. The acrosome is larger in C. quadricarinatus (width 2.37 ± 0.27 μm, length 1.31 ± 0.23 μm) than in C. destructor (width 1.80 ± 0.27 μm, length 1.01 ± 0.15 μm). There was no significant difference in L:W ratios of the studied species. The subacrosome zone in both species consists of two areas of different electron density. The nucleus is substantially decondensed and irregular in shape, with elaborate extended processes. The examined species exhibited a well-conserved structure of crayfish spermatozoon, similar to those of Cherax cainii and Cherax albidus. Small acrosome size, the absence of radial arms, and an extracellular capsule seem to be the morphological features that mostly distinguish Cherax from the Astacidae and Cambaridae.
Martin Bláha - One of the best experts on this subject based on the ideXlab platform.
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Cherax acherontis (Decapoda: Parastacidae), the first cave crayfish from the Southern Hemisphere (Papua Province, Indonesia).
Zootaxa, 2017Co-Authors: Jiří Patoka, Martin Bláha, Antonin KoubaAbstract:Cherax acherontis n. sp., is a crayfish endemic to the submerged river Yumugima in Hagepma/Jugurama cave in the New Guinea Highlands, Jayawijaya Regency, Papua Province, Indonesia. This species is the first cave crayfish from the Southern Hemisphere. The new species is most similar to Cherax monticola . Both species can be easily distinguished by certain morphological characteristics, which easily demonstrate C. acherontis n. sp. is a valid species.
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Cherax (Cherax) Subterigneus, A New Crayfish (Decapoda: Parastacidae) from West Papua, Indonesia
Journal of Crustacean Biology, 2015Co-Authors: Jiří Patoka, Martin Bláha, Antonin KoubaAbstract:Cherax ( Cherax ) subterigneus n. sp., is a crayfish endemic to the Aitinjo Lake of West Papua, Indonesia. This species is one of the field-captured species from this region that are exploited for ornamental purposes. Its commonly used commercial name in the pet trade is “Black Orange Tip Crayfish,” “Orange Tip Crayfish,” or “Red Tip Crayfish.” The new species is genetically and morphologically similar to Cherax holthuisi , however, both species can be easily distinguished by certain morphological characteristics or by using sequence divergence, which is substantial, for considering C. subterigneus n. sp. as a valid species. We have also added a note about the probable incorrect subgeneric assignment of the Cherax peknyi and mandatory change of incorrect original spelling of recently described C. gherardii as C. gherardiae .
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Cherax (Astaconephrops) gherardii, a new crayfish (Decapoda: Parastacidae) from West Papua, Indonesia.
Zootaxa, 2015Co-Authors: Jiří Patoka, Martin Bláha, Antonin KoubaAbstract:Cherax ( Astaconephrops ) gherardii n. sp. is a moderate burrowing crayfish endemic to the Ajamaru Lakes of West Papua, Indonesia. This species is one of the crayfish species from this region that are exploited for ornamental purposes. Its commonly used commercial name in the pet trade is “Rainbow Crayfish” or “Blue Moon Crayfish”, and its native name is “udang kuku biru”. The new species is genetically and morphologically similar to Cherax boesemani , however, both species may be easily distinguished morphologically or by using sequence divergence, which is substantial for considering C. gherardii n. sp. to be a valid species.
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comparative ultrastructure of spermatozoa of the redclaw Cherax quadricarinatus and the yabby Cherax destructor decapoda parastacidae
Micron, 2015Co-Authors: Antonin Kouba, Hamid Niksirat, Martin BláhaAbstract:Abstract Ultrastructure of spermatozoa of redclaw Cherax quadricarinatus and yabby Cherax destructor were described and compared. The acrosome complex and nucleus are located at the anterior and posterior region of the spermatozoon, respectively. The acrosome is a complex vesicle divided into two parts: the main body of the acrosome appears as a dense cup-shaped structure in longitudinal sagittal view, with the subacrosome zone occupying the central area of the vesicle. The acrosome is larger in C. quadricarinatus (width 2.37 ± 0.27 μm, length 1.31 ± 0.23 μm) than in C. destructor (width 1.80 ± 0.27 μm, length 1.01 ± 0.15 μm). There was no significant difference in L:W ratios of the studied species. The subacrosome zone in both species consists of two areas of different electron density. The nucleus is substantially decondensed and irregular in shape, with elaborate extended processes. The examined species exhibited a well-conserved structure of crayfish spermatozoon, similar to those of Cherax cainii and Cherax albidus. Small acrosome size, the absence of radial arms, and an extracellular capsule seem to be the morphological features that mostly distinguish Cherax from the Astacidae and Cambaridae.
S.g. Ryan - One of the best experts on this subject based on the ideXlab platform.
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Genetic diversity and translocation in the marron, Cherax tenuimanus (Smith): implications for management and conservation
Fisheries Management and Ecology, 2002Co-Authors: Thuy T. T. Nguyen, S.g. Ryan, Maliwan Meewan, Christopher M AustinAbstract:Approximately 440 base pairs (bp) of the mitochondrial 16S ribosomal ribose nucleic acid (rRNA) coding region were sequenced from 13 marron, Cherax tenuimanus (Smith), samples from six locations and samples of two additional Cherax species from Western Australia. The results indicated that, with the exception of the Margaret River, no variation was found within or between marron populations. In contrast, marron from the Margaret River were found to be polymorphic for two divergent haplotypes (2.76% divergence). These findings were consistent with allozyme data that highlight the general lack of genetic variability within and between populations of this species apart from the Margaret River stocks. The genetic polymorphisms in the Margaret River stocks contrasted with earlier studies and indicated the recent translocation and mixing of genetically differentiated stocks within this river system. The implications of these findings for the conservation and management of genetic diversity within marron are discussed.
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Allozyme evidence for a new species of freshwater crayfish of the genus Cherax Erichson (Decapoda : Parastacidae) from the south-west of Western Australia
Invertebrate Systematics, 2002Co-Authors: Christopher M Austin, S.g. RyanAbstract:The marron, Cherax tenuimanus (Smith), is one of the most easily recognisable members of the freshwater crayfish genus Cherax. Since its description in 1912, the taxonomy of the species has not been in dispute, but recent genetic studies have demonstrated that the species is not homogenous and consists of two genetically distinct forms. One of these forms is widespread and exploited via aquaculture and the other is restricted to a single river system, the Margaret River. This paper presents allozyme data, collected over a 19-year period, which documents the introduction of the widespread form into the Margaret River and the subsequent reproductive interactions between the two forms. These data indicate minimal interbreeding between the two forms of marron and so justify their recognition as distinct species. As the original description of the marron was based on specimens collected from the Margaret River, the form native to this river retains the name C. tenuimanus and a new species, Cherax cainii Austin is described for the common, widespread form of marron. An additional outcome of this study is that C. tenuimanus has been rapidly displaced by the introduced C. cainii within the Margaret River. Consequently, urgent conservation measures are required to protect C. tenuimanus and prevent its possible extinction.