Displaying publications 61 - 80 of 175 in total

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  1. Cheng TH, Saidin J, Danish-Daniel M, Gan HM, Mat Isa MN, Abu Bakar MF, et al.
    Genome Announc, 2018 Feb 08;6(6).
    PMID: 29439033 DOI: 10.1128/genomeA.00022-18
    Serratia marcescens
    subsp.sakuensisstrain K27 was isolated from sponge (Haliclona amboinensis). The genome of this strain consists of 5,325,727 bp, with 5,140 open reading frames (ORFs), 3 rRNAs, and 67 tRNAs. It contains genes for the production of amylases, lipases, and proteases. Gene clusters for the biosynthesis of nonribosomal peptides and thiopeptide were also identified.
  2. Foo SM, Eng WWH, Lee YP, Gui K, Gan HM
    Genome Announc, 2017 May 11;5(19).
    PMID: 28495773 DOI: 10.1128/genomeA.00302-17
    The acquisition of Photorhabdus insect-related (Pir) toxin-like genes in Vibrio parahaemolyticus has been linked to hepatopancreatic necrosis disease in shrimp. We report the whole-genome sequences of genetically virulent and avirulent V. parahaemolyticus isolated from a Malaysian aquaculture pond and show that they represent previously unreported sequence types of V. parahaemolyticus.
  3. 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.
  4. Torres ME, Cox T, Hong WL, McManus J, Sample JC, Destrigneville C, et al.
    Geobiology, 2015 Nov;13(6):562-80.
    PMID: 26081483 DOI: 10.1111/gbi.12146
    We present data from sediment cores collected from IODP Site C0012 in the Shikoku Basin. Our site lies at the Nankai Trough, just prior to subduction of the 19 Ma Philippine Sea plate. Our data indicate that the sedimentary package is undergoing multiple routes of electron transport and that these differing pathways for oxidant supply generate a complex array of metabolic routes and microbial communities involved in carbon cycling. Numerical simulations matched to pore water data document that Ca(2+) and Cl(1-) are largely supplied via diffusion from a high-salinity (44.5 psu) basement fluid, which supports the presence of halophile Archean communities within the deep sedimentary package that are not observed in shallow sediments. Sulfate supply from basement supports anaerobic oxidation of methane (AOM) at a rate of ~0.2 pmol cm(-3) day(-1) at ~400 mbsf. We also note the disappearance of δ-Proteobacteria at 434 mbsf, coincident with the maximum in methane concentration, and their reappearance at 463 mbsf, coinciding with the observed deeper increase in sulfate concentration toward the basement. We did not, however, find ANME representatives in any of the samples analyzed (from 340 to 463 mbsf). The lack of ANME may be due to an overshadowing effect from the more dominant archaeal phylotypes or may indicate involvement of unknown groups of archaea in AOM (i.e., unclassified Euryarchaeota). In addition to the supply of sulfate from a basement aquifer, the deep biosphere at this site is also influenced by an elevated supply of reactive iron (up to 143 μmol g(-1)) and manganese (up to 20 μmol g(-1)). The effect of these metal oxides on the sulfur cycle is inferred from an accompanying sulfur isotope fractionation much smaller than expected from traditional sulfate-reducing pathways. The detection of the manganese- and iron-reducer γ-Proteobacteria Alteromonas at 367 mbsf is consistent with these geochemical inferences.
  5. 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.

  6. 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.
  7. Robledo-Ruiz DA, Gan HM, Kaur P, Dudchenko O, Weisz D, Khan R, et al.
    Gigascience, 2022 Mar 29;11.
    PMID: 35348671 DOI: 10.1093/gigascience/giac025
    BACKGROUND: The helmeted honeyeater (Lichenostomus melanops cassidix) is a Critically Endangered bird endemic to Victoria, Australia. To aid its conservation, the population is the subject of genetic rescue. To understand, monitor, and modulate the effects of genetic rescue on the helmeted honeyeater genome, a chromosome-length genome and a high-density linkage map are required.

    RESULTS: We used a combination of Illumina, Oxford Nanopore, and Hi-C sequencing technologies to assemble a chromosome-length genome of the helmeted honeyeater, comprising 906 scaffolds, with length of 1.1 Gb and scaffold N50 of 63.8 Mb. Annotation comprised 57,181 gene models. Using a pedigree of 257 birds and 53,111 single-nucleotide polymorphisms, we obtained high-density linkage and recombination maps for 25 autosomes and Z chromosome. The total sex-averaged linkage map was 1,347 cM long, with the male map being 6.7% longer than the female map. Recombination maps revealed sexually dimorphic recombination rates (overall higher in males), with average recombination rate of 1.8 cM/Mb. Comparative analyses revealed high synteny of the helmeted honeyeater genome with that of 3 passerine species (e.g., 32 Hi-C scaffolds mapped to 30 zebra finch autosomes and Z chromosome). The genome assembly and linkage map suggest that the helmeted honeyeater exhibits a fission of chromosome 1A into 2 chromosomes relative to zebra finch. PSMC analysis showed a ∼15-fold decline in effective population size to ∼60,000 from mid- to late Pleistocene.

    CONCLUSIONS: The annotated chromosome-length genome and high-density linkage map provide rich resources for evolutionary studies and will be fundamental in guiding conservation efforts for the helmeted honeyeater.

  8. Mohd Shaufi MA, Sieo CC, Chong CW, Gan HM, Ho YW
    Gut Pathog, 2015;7:4.
    PMID: 25806087 DOI: 10.1186/s13099-015-0051-7
    Chicken gut microbiota has paramount roles in host performance, health and immunity. Understanding the topological difference in gut microbial community composition is crucial to provide knowledge on the functions of each members of microbiota to the physiological maintenance of the host. The gut microbiota profiling of the chicken was commonly performed previously using culture-dependent and early culture-independent methods which had limited coverage and accuracy. Advances in technology based on next-generation sequencing (NGS), offers unparalleled coverage and depth in determining microbial gut dynamics. Thus, the aim of this study was to investigate the ileal and caecal microbiota development as chicken aged, which is important for future effective gut modulation.
  9. Harrisson K, Pavlova A, Gan HM, Lee YP, Austin CM, Sunnucks P
    Heredity (Edinb), 2016 Jun;116(6):506-15.
    PMID: 26883183 DOI: 10.1038/hdy.2016.8
    Climatic differences across a taxon's range may be associated with specific bioenergetic demands and may result in genetics-based metabolic adaptation, particularly in aquatic ectothermic organisms that rely on heat exchange with the environment to regulate key physiological processes. Extending down the east coast of Australia, the Great Dividing Range (GDR) has a strong influence on climate and the evolutionary history of freshwater fish species. Despite the GDR acting as a strong contemporary barrier to fish movement, many species, and species with shared ancestries, are found on both sides of the GDR, indicative of historical dispersal events. We sequenced complete mitogenomes from the four extant species of the freshwater cod genus Maccullochella, two of which occur on the semi-arid, inland side of the GDR, and two on the mesic coastal side. We constructed a dated phylogeny and explored the relative influences of purifying and positive selection in the evolution of mitogenome divergence among species. Results supported mid- to late-Pleistocene divergence of Maccullochella across the GDR (220-710 thousand years ago), bringing forward previously reported dates. Against a background of pervasive purifying selection, we detected potentially functionally relevant fixed amino acid differences across the GDR. Although many amino acid differences between inland and coastal species may have become fixed under relaxed purifying selection in coastal environments rather than positive selection, there was evidence of episodic positive selection acting on specific codons in the Mary River coastal lineage, which has consistently experienced the warmest and least extreme climate in the genus.
  10. Pavlova A, Gan HM, Lee YP, Austin CM, Gilligan DM, Lintermans M, et al.
    Heredity (Edinb), 2017 05;118(5):466-476.
    PMID: 28051058 DOI: 10.1038/hdy.2016.120
    Genetic variation in mitochondrial genes could underlie metabolic adaptations because mitochondrially encoded proteins are directly involved in a pathway supplying energy to metabolism. Macquarie perch from river basins exposed to different climates differ in size and growth rate, suggesting potential presence of adaptive metabolic differences. We used complete mitochondrial genome sequences to build a phylogeny, estimate lineage divergence times and identify signatures of purifying and positive selection acting on mitochondrial genes for 25 Macquarie perch from three basins: Murray-Darling Basin (MDB), Hawkesbury-Nepean Basin (HNB) and Shoalhaven Basin (SB). Phylogenetic analysis resolved basin-level clades, supporting incipient speciation previously inferred from differentiation in allozymes, microsatellites and mitochondrial control region. The estimated time of lineage divergence suggested an early- to mid-Pleistocene split between SB and the common ancestor of HNB+MDB, followed by mid-to-late Pleistocene splitting between HNB and MDB. These divergence estimates are more recent than previous ones. Our analyses suggested that evolutionary drivers differed between inland MDB and coastal HNB. In the cooler and more climatically variable MDB, mitogenomes evolved under strong purifying selection, whereas in the warmer and more climatically stable HNB, purifying selection was relaxed. Evidence for relaxed selection in the HNB includes elevated transfer RNA and 16S ribosomal RNA polymorphism, presence of potentially mildly deleterious mutations and a codon (ATP6113) displaying signatures of positive selection (ratio of nonsynonymous to synonymous substitution rates (dN/dS) >1, radical change of an amino-acid property and phylogenetic conservation across the Percichthyidae). In addition, the difference could be because of stronger genetic drift in the smaller and historically more subdivided HNB with low per-population effective population sizes.
  11. Froufe E, Bolotov I, Aldridge DC, Bogan AE, Breton S, Gan HM, et al.
    Heredity (Edinb), 2020 Jan;124(1):182-196.
    PMID: 31201385 DOI: 10.1038/s41437-019-0242-y
    Using a new fossil-calibrated mitogenome-based approach, we identified macroevolutionary shifts in mitochondrial gene order among the freshwater mussels (Unionoidea). We show that the early Mesozoic divergence of the two Unionoidea clades, Margaritiferidae and Unionidae, was accompanied by a synchronous split in the gene arrangement in the female mitogenome (i.e., gene orders MF1 and UF1). Our results suggest that this macroevolutionary jump was completed within a relatively short time interval (95% HPD 201-226 Ma) that coincided with the Triassic-Jurassic mass extinction. Both gene orders have persisted within these clades for ~200 Ma. The monophyly of the so-called "problematic" Gonideinae taxa was supported by all the inferred phylogenies in this study using, for the first time, the M- and F-type mitogenomes either singly or combined. Within Gonideinae, two additional splits in the gene order (UF1 to UF2, UF2 to UF3) occurred in the Mesozoic and have persisted for ~150 and ~100 Ma, respectively. Finally, the mitogenomic results suggest ancient connections between freshwater basins of East Asia and Europe near the Cretaceous-Paleogene boundary, probably via a continuous paleo-river system or along the Tethys coastal line, which are well supported by at least three independent but almost synchronous divergence events.
  12. Taheri S, Teo CH, Heslop-Harrison JS, Schwarzacher T, Tan YS, Wee WY, et al.
    Int J Mol Sci, 2022 Jun 30;23(13).
    PMID: 35806276 DOI: 10.3390/ijms23137269
    Boesenbergia rotunda (Zingiberaceae), is a high-value culinary and ethno-medicinal plant of Southeast Asia. The rhizomes of this herb have a high flavanone and chalcone content. Here we report the genome analysis of B. rotunda together with a complete genome sequence as a hybrid assembly. B. rotunda has an estimated genome size of 2.4 Gb which is assembled as 27,491 contigs with an N50 size of 12.386 Mb. The highly heterozygous genome encodes 71,072 protein-coding genes and has a 72% repeat content, with class I TEs occupying ~67% of the assembled genome. Fluorescence in situ hybridization of the 18 chromosome pairs at the metaphase showed six sites of 45S rDNA and two sites of 5S rDNA. An SSR analysis identified 238,441 gSSRs and 4604 EST-SSRs with 49 SSR markers common among related species. Genome-wide methylation percentages ranged from 73% CpG, 36% CHG and 34% CHH in the leaf to 53% CpG, 18% CHG and 25% CHH in the embryogenic callus. Panduratin A biosynthetic unigenes were most highly expressed in the watery callus. B rotunda has a relatively large genome with a high heterozygosity and TE content. This assembly and data (PRJNA71294) comprise a source for further research on the functional genomics of B. rotunda, the evolution of the ginger plant family and the potential genetic selection or improvement of gingers.
  13. Tang HC, Sieo CC, Abdullah N, Chong CW, Gan HM, Mohd Asrore MS, et al.
    J Anim Physiol Anim Nutr (Berl), 2020 Jan;104(1):116-125.
    PMID: 31556187 DOI: 10.1111/jpn.13208
    Inclusion of phytase in animal feedstuff is a common practice to enhance nutrients availability. However, little is known about the effects of phytase supplementation on the microbial ecology of the gastrointestinal tract. In this study, freeze-dried Mitsuokella jalaludinii phytase (MJ) was evaluated in a feeding trial with broilers fed a low available phosphorus (aP) diet. A total of 180 male broiler chicks (day-old Cobb) were assigned into three dietary treatments: Control fed with 0.4% (w/w) of available phosphorus (aP); Group T1 fed low aP [0.2% (w/w)] supplemented with MJ; and T2 fed low aP and deactivated MJ. The source of readily available P, dicalcium phosphate (DCP), was removed from low aP diet, whereby additional limestone was provided to replace the amount of Ca normally found in DCP. For each treatment, 4 replicate pens were used, where each pen consisted of 15 animals. The animals' energy intake and caecal bacterial community were monitored weekly for up to 3 weeks. The apparent metabolizable energy (AME) and apparent digestibility of dry matter (ADDM) of broilers fed with different diets were determined. In addition, the caecal microbial diversities of broilers were assessed using high-throughput next-generation sequencing targeting the V3-V4 region of bacterial 16S rRNA. The results showed that broilers fed with T1 diet have better feed conversion ratio (FCR) when compared to the Control (p 
  14. Saminathan M, Gan HM, Abdullah N, Wong CMVL, Ramiah SK, Tan HY, et al.
    J Appl Microbiol, 2017 Apr 23.
    PMID: 28434189 DOI: 10.1111/jam.13477
    AIMS: To evaluate the effects of condensed tannins (CTs) fractions of differing molecular weights (MWs) from a Leucaena leucocephala hybrid-Rendang on the rumen protozoal community in vitro.

    METHODS AND RESULTS: The effects of unfractionated CTs (F0) and CT fractions of different MWs (F1 > F2 > F3 > F4 > F5) on protozoal population and community were evaluated in vitro using rumen microbes and ground guinea grass as the substrate. Higher-MW CT fractions F1 and F2 significantly (P 

  15. Osama A, Gan HM, Teh CS, Yap KP, Thong KL
    J Bacteriol, 2012 Dec;194(24):6933.
    PMID: 23209200 DOI: 10.1128/JB.01832-12
    The genome sequence analysis of a clinical Vibrio cholerae VC35 strain from an outbreak case in Malaysia indicates multiple genes involved in host adaptation and a novel Na(+)-driven multidrug efflux pump-coding gene in the genome of Vibrio cholerae with the highest similarity to VMA_001754 of Vibrio mimicus VMA223.
  16. Ho WS, Gan HM, Yap KP, Balan G, Yeo CC, Thong KL
    J Bacteriol, 2012 Dec;194(23):6691-2.
    PMID: 23144425 DOI: 10.1128/JB.01804-12
    Escherichia coli is an important etiologic agent of lower respiratory tract infections (LRTI). Multidrug-resistant E. coli EC302/04 was isolated from a tracheal aspirate, and its genome sequence is expected to provide insights into antimicrobial resistance as well as adaptive and virulence mechanisms of E. coli involved in LRTI.
  17. Chen JW, Gan HM, Yin WF, Chan KG
    J Bacteriol, 2012 Dec;194(23):6681-2.
    PMID: 23144419 DOI: 10.1128/JB.01866-12
    Roseomonas sp. strain B5 was isolated from Malaysian tropical soil that showed N-acylhomoserine lactone degradation. This is the first genome announcement of a member from the genus of Roseomonas and the first report on the quorum-quenching activity of Roseomonas spp.
  18. Hong KW, Gan HM, Low SM, Lee PK, Chong YM, Yin WF, et al.
    J Bacteriol, 2012 Dec;194(23):6610.
    PMID: 23144374 DOI: 10.1128/JB.01619-12
    Pantoea sp. strain A4 is a Gram-negative bacterium isolated from the Rafflesia flower. We present here, for the first time, the genome sequence of Rafflesia-associated Pantoea sp. strain A4, which exhibited quorum-sensing activity.
  19. Hong KW, Thinagaran Da, Gan HM, Yin WF, Chan KG
    J Bacteriol, 2012 Nov;194(22):6324.
    PMID: 23115161 DOI: 10.1128/JB.01608-12
    Cupriavidus sp. strain BIS7 is a Malaysian tropical soil bacterium that exhibits broad heavy-metal resistance [Co(II), Zn(II), Ni(II), Se(IV), Cu(II), chromate, Co(III), Fe(II), and Fe(III)]. It is particularly resistant to Fe(II), Fe(III), and Zn(II). Here we present the assembly and annotation of its genome.
  20. Chan GF, Gan HM, Rashid NA
    J Bacteriol, 2012 Oct;194(20):5716-7.
    PMID: 23012290
    Enterococcus sp. strain C1 is a facultative anaerobe which was coisolated with Citrobacter sp. strain A1 from a sewage oxidation pond. Strain C1 could degrade azo dyes very efficiently via azo reduction and desulfonation in a microaerophilic environment. Here the draft genome sequence of Enterococcus sp. C1 is reported.
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