MyMedR

The complete mitogenome of the freshwater crayfish Cherax cainii (Crustacea: Decapoda: Parastacidae)

Austin CM, Tan MH, Croft LJ, Gan HM

Mitochondrial DNA, 2016;27(1):126-7.

PMID: 24438281 DOI: 10.3109/19401736.2013.878907

The complete mitochondrial genome of Cherax cainii was recovered from partial genome sequencing data using the HiSeq platform. The mitogenome consists of 15,801 base pairs (69% A + T content) containing 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs and a 783 bp non-coding AT-rich region. This is the second completely sequenced mitogenome from the genus Cherax after the first reported Cherax destructor mitogenome nearly a decade ago.

The complete mitogenome of the crayfish Cherax glaber (Crustacea: Decapoda: Parastacidae)

Austin CM, Tan MH, Croft LJ, Gan HM

Mitochondrial DNA, 2016;27(1):220-1.

PMID: 24484586 DOI: 10.3109/19401736.2014.880897

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%.

Fulltext The NGS Magic Pudding: A Nanopore-Led Long-Read Genome Assembly for the Commercial Australian Freshwater Crayfish, Cherax destructor

Austin CM, Croft LJ, Grandjean F, Gan HM

Front Genet, 2021;12:695763.

PMID: 35126445 DOI: 10.3389/fgene.2021.695763

Cherax destructor, the yabby, is an iconic Australian freshwater crayfish species, which, similar to other major invertebrate groups, is grossly under-represented in genomic databases. The yabby is also the principal commercial freshwater crustacean species in Australia subject to explotation via inland fisheries and aquaculture. To address the genomics knowledge gap for this species and explore cost effective and efficient methods for genome assembly, we generated 106.8 gb of Nanopore reads and performed a long-read only assembly of the Cherax destructor genome. On a mini-server configured with an ultra-fast swap space, the de novo assembly took 131 h (∼5.5 days). Genome polishing with 126.3 gb of PCR-Free Illumina reads generated an assembled genome size of 3.3 gb (74.6% BUSCO completeness) with a contig N50 of 80,900 bp, making it the most contiguous for freshwater crayfish genome assemblies. We found an unusually large number of cellulase genes within the yabby genome which is relevant to understanding the nutritional biology, commercial feed development, and ecological role of this species and crayfish more generally. These resources will be useful for genomic research on freshwater crayfish and our methods for rapid and super-efficient genome assembly will have wide application.

The complete mitogenome of the bluespotted ribbontail ray Taeniura lymma (Forsskål, 1775) (Elasmobranchii: Myliobatiformes: Dasyatidae)

Austin CM, Tan MH, Croft LJ, Meekan MG, Gan HY, Gan HM

Mitochondrial DNA A DNA Mapp Seq Anal, 2016 09;27(5):3205-7.

PMID: 25693694 DOI: 10.3109/19401736.2015.1007348

The complete mitogenome of the ray Taeniura lymma was recovered from genome skimming using the HiSeq sequencing system. The T. lymma mitogenome has 17,652 base pairs (59.13% A + T content) made up of 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs and a 1906 bp non-coding AT-rich region. This mitogenome sequence is the second for a ray from Australian waters, the first for the genus Taeniura and the ninth for the family Dasyatidae.

The complete mitogenome of the cow tail ray Pastinachus atrus (Macleay, 1883) (Elasmobranchii; Myliobatiformes; Dasyatidae)

Austin CM, Tan MH, Lee YP, Croft LJ, Meekan MG, Gan HM

Mitochondrial DNA A DNA Mapp Seq Anal, 2016;27(2):1372-3.

PMID: 25103432 DOI: 10.3109/19401736.2014.947586

The complete mitogenome of the ray Pastinachus atrus was recovered from a partial genome scan using the HiSeq sequencing system. The P. atrus mitogenome has 18,162 base pairs (61% A + T content) made up of 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs, and a 2516 bp non-coding AT-rich region. This mitogenome sequence is the first for a ray from Australian waters, the first for the Genus Pastinachus, and the 6th for the family Dasyatidae.

The complete mitogenome of the whale shark parasitic copepod Pandarus rhincodonicus norman, Newbound & Knott (Crustacea; Siphonostomatoida; Pandaridae)--a new gene order for the copepoda

Austin CM, Tan MH, Lee YP, Croft LJ, Meekan MG, Pierce SJ, et al.

Mitochondrial DNA, 2016;27(1):694-5.

PMID: 24779605 DOI: 10.3109/19401736.2014.913147

The complete mitochondrial genome of the parasitic copepod Pandarus rhincodonicus was obtained from a partial genome scan using the HiSeq sequencing system. The Pandarus rhincodonicus mitogenome has 14,480 base pairs (62% A+T content) made up of 12 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs, and a putative 384 bp non-coding AT-rich region. This Pandarus mitogenome sequence is the first for the family Pandaridae, the second for the order Siphonostomatoida and the sixth for the Copepoda.

The complete mitogenome of the Murray Cod, Maccullochella peelii (Mitchell, 1838) (Teleostei: Percichthyidae)

Austin CM, Tan MH, Lee YP, Croft LJ, Gan HM

Mitochondrial DNA, 2016;27(1):729-30.

PMID: 24779601 DOI: 10.3109/19401736.2014.913162

The complete mitochondrial genome of the iconic Australian freshwater fish, the Murray Cod, Maccullochella peelii, was recovered from partial genome sequencing data using the HiSeq platform (Illumina, San Diego, CA). The mitogenome consists of 16,442 bp (58% A + T content) containing 13 protein-coding genes, 2 ribosomal subunit genes, 22 transfer RNAs, and a 768 bp non-coding AT-rich region. This is the first mitogenome sequence for the genus Maccullochella, and the fourth for the family Percichthyidae.

Fulltext Whole Genome Sequencing of the Asian Arowana (Scleropages formosus) Provides Insights into the Evolution of Ray-Finned Fishes

Austin CM, Tan MH, Croft LJ, Hammer MP, Gan HM

Genome Biol Evol, 2015 Oct;7(10):2885-95.

PMID: 26446539 DOI: 10.1093/gbe/evv186

The Asian arowana (Scleropages formosus) is of commercial importance, conservation concern, and is a representative of one of the oldest lineages of ray-finned fish, the Osteoglossomorpha. To add to genomic knowledge of this species and the evolution of teleosts, the genome of a Malaysian specimen of arowana was sequenced. A draft genome is presented consisting of 42,110 scaffolds with a total size of 708 Mb (2.85% gaps) representing 93.95% of core eukaryotic genes. Using a k-mer-based method, a genome size of 900 Mb was also estimated. We present an update on the phylogenomics of fishes based on a total of 27 species (23 fish species and 4 tetrapods) using 177 orthologous proteins (71,360 amino acid sites), which supports established relationships except that arowana is placed as the sister lineage to all teleost clades (Bayesian posterior probability 1.00, bootstrap replicate 93%), that evolved after the teleost genome duplication event rather than the eels (Elopomorpha). Evolutionary rates are highly heterogeneous across the tree with fishes represented by both slowly and rapidly evolving lineages. A total of 94 putative pigment genes were identified, providing the impetus for development of molecular markers associated with the spectacular colored phenotypes found within this species.

Fulltext Finding Nemo: hybrid assembly with Oxford Nanopore and Illumina reads greatly improves the clownfish (Amphiprion ocellaris) genome assembly

Tan MH, Austin CM, Hammer MP, Lee YP, Croft LJ, Gan HM

Gigascience, 2018 03 01;7(3):1-6.

PMID: 29342277 DOI: 10.1093/gigascience/gix137

Background: Some of the most widely recognized coral reef fishes are clownfish or anemonefish, members of the family Pomacentridae (subfamily: Amphiprioninae). They are popular aquarium species due to their bright colours, adaptability to captivity, and fascinating behavior. Their breeding biology (sequential hermaphrodites) and symbiotic mutualism with sea anemones have attracted much scientific interest. Moreover, there are some curious geographic-based phenotypes that warrant investigation. Leveraging on the advancement in Nanopore long read technology, we report the first hybrid assembly of the clown anemonefish (Amphiprion ocellaris) genome utilizing Illumina and Nanopore reads, further demonstrating the substantial impact of modest long read sequencing data sets on improving genome assembly statistics.

Results: We generated 43 Gb of short Illumina reads and 9 Gb of long Nanopore reads, representing approximate genome coverage of 54× and 11×, respectively, based on the range of estimated k-mer-predicted genome sizes of between 791 and 967 Mbp. The final assembled genome is contained in 6404 scaffolds with an accumulated length of 880 Mb (96.3% BUSCO-calculated genome completeness). Compared with the Illumina-only assembly, the hybrid approach generated 94% fewer scaffolds with an 18-fold increase in N50 length (401 kb) and increased the genome completeness by an additional 16%. A total of 27 240 high-quality protein-coding genes were predicted from the clown anemonefish, 26 211 (96%) of which were annotated functionally with information from either sequence homology or protein signature searches.

Conclusions: We present the first genome of any anemonefish and demonstrate the value of low coverage (∼11×) long Nanopore read sequencing in improving both genome assembly contiguity and completeness. The near-complete assembly of the A. ocellaris genome will be an invaluable molecular resource for supporting a range of genetic, genomic, and phylogenetic studies specifically for clownfish and more generally for other related fish species of the family Pomacentridae.

Fulltext Insights into microbial community structure and diversity in oil palm waste compost

Khalid NA, Rajandas H, Parimannan S, Croft LJ, Loke S, Chong CS, et al.

3 Biotech, 2019 Oct;9(10):364.

PMID: 31588388 DOI: 10.1007/s13205-019-1892-4

Empty fruit bunch (EFB) and palm oil mill effluent (POME) are the major wastes generated by the oil palm industry in Malaysia. The practice of EFB and POME digester sludge co-composting has shown positive results, both in mitigating otherwise environmentally damaging waste streams and producing a useful product (compost) from these streams. In this study, the bacterial ecosystems of 12-week-old EFB-POME co-compost and POME biogas sludge from Felda Maokil, Johor were analysed using 16S metagenome sequencing. Over ten phyla were detected, with Chloroflexi being the predominant phylum, representing approximately 53% of compost and 23% of the POME microbiome reads. The main bacterial lineage found in the compost and POME was Anaerolinaceae (Chloroflexi) with 30% and 18% of the total gene fragments, respectively. The significant differences between compost and POME communities were abundances of Syntrophobacter, Sulfuricurvum and Coprococcus. No methanogens were identified due to the bias in general 16S primers to eubacteria. The preponderance of anaerobic species in the compost and high abundance of secondary metabolite fermenting bacteria is due to an extended composting time, with anaerobic collapse of the pile due to the tropical heat. Predictive functional profiles of the metagenomes using 16S rRNA marker genes suggest that the presence of enzymes involved in degradation of polysaccharides such as glucoamylase, endoglucanase and arabinofuranosidase, all of which were strongly active in POME. Eubacterial species associated with cellulytic methanogenesis were present in both samples.

Fulltext Helicobacter pylori genetic diversity and gastro-duodenal diseases in Malaysia

Gunaletchumy SP, Seevasant I, Tan MH, Croft LJ, Mitchell HM, Goh KL, et al.

Sci Rep, 2014 Dec 11;4:7431.

PMID: 25503415 DOI: 10.1038/srep07431

Helicobacter pylori infection results in diverse clinical conditions ranging from chronic gastritis and ulceration to gastric adenocarcinoma. Among the multiethnic population of Malaysia, Indians consistently have a higher H. pylori prevalence as compared with Chinese and Malays. Despite the high prevalence of H. pylori, Indians have a relatively low incidence of peptic ulcer disease and gastric cancer. In contrast, gastric cancer and peptic ulcer disease incidence is high in Chinese. H. pylori strains from Chinese strains predominantly belong to the hspEAsia subpopulation while Indian/Malay strains mainly belong to the hspIndia subpopulation. By comparing the genome of 27 Asian strains from different subpopulations, we identified six genes associated with risk of H. pylori-induced peptic ulcer disease and gastric cancer. This study serves as an important foundation for future studies aiming to understand the role of bacterial factors in H. pylori-induced gastro-duodenal diseases.

Fulltext De novo genome assembly and annotation of Australia's largest freshwater fish, the Murray cod (Maccullochella peelii), from Illumina and Nanopore sequencing read

Austin CM, Tan MH, Harrisson KA, Lee YP, Croft LJ, Sunnucks P, et al.

Gigascience, 2017 08 01;6(8):1-6.

PMID: 28873963 DOI: 10.1093/gigascience/gix063

One of the most iconic Australian fish is the Murray cod, Maccullochella peelii (Mitchell 1838), a freshwater species that can grow to ∼1.8 metres in length and live to age ≥48 years. The Murray cod is of a conservation concern as a result of strong population contractions, but it is also popular for recreational fishing and is of growing aquaculture interest. In this study, we report the whole genome sequence of the Murray cod to support ongoing population genetics, conservation, and management research, as well as to better understand the evolutionary ecology and history of the species. A draft Murray cod genome of 633 Mbp (N50 = 109 974bp; BUSCO and CEGMA completeness of 94.2% and 91.9%, respectively) with an estimated 148 Mbp of putative repetitive sequences was assembled from the combined sequencing data of 2 fish individuals with an identical maternal lineage; 47.2 Gb of Illumina HiSeq data and 804 Mb of Nanopore data were generated from the first individual while 23.2 Gb of Illumina MiSeq data were generated from the second individual. The inclusion of Nanopore reads for scaffolding followed by subsequent gap-closing using Illumina data led to a 29% reduction in the number of scaffolds and a 55% and 54% increase in the scaffold and contig N50, respectively. We also report the first transcriptome of Murray cod that was subsequently used to annotate the Murray cod genome, leading to the identification of 26 539 protein-coding genes. We present the whole genome of the Murray cod and anticipate this will be a catalyst for a range of genetic, genomic, and phylogenetic studies of the Murray cod and more generally other fish species of the Percichthydae family.

Fulltext Multiple Genome Sequences of Helicobacter pylori Strains of Diverse Disease and Antibiotic Resistance Backgrounds from Malaysia

Rehvathy V, Tan MH, Gunaletchumy SP, Teh X, Wang S, Baybayan P, et al.

Genome Announc, 2013;1(5).

PMID: 24051312 DOI: 10.1128/genomeA.00687-13

Helicobacter pylori causes human gastroduodenal diseases, including chronic gastritis and peptic ulcer disease. It is also a major microbial risk factor for the development of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Twenty-one strains with different ethnicity, disease, and antimicrobial susceptibility backgrounds were sequenced by use of Illumina HiSeq and PacBio RS platforms.

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