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  1. Yew CW, Kumar SV
    Mol Biol Rep, 2012 Feb;39(2):1783-90.
    PMID: 21625851 DOI: 10.1007/s11033-011-0919-7
    MicroRNAs (miRNAs) are small RNAs (sRNAs) with approximately 21-24 nucleotides in length. They regulate the expression of target genes through the mechanism of RNA silencing. Conventional isolation and cloning of miRNAs methods are usually technical demanding and inefficient. These limitations include the requirement for high amounts of starting total RNA, inefficient ligation of linkers, high amount of PCR artifacts and bias in the formation of short miRNA-concatamers. Here we describe in detail a method that uses 80 μg of total RNA as the starting material. Enhancement of the ligation of sRNAs and linkers with the use of polyethylene glycol (PEG8000) was described. PCR artifacts from the amplification of reverse-transcribed sRNAs were greatly decreased by using lower concentrations of primers and reducing the number of amplification cycles. Large concatamers with up to 1 kb in size with around 20 sRNAs/concatamer were obtained by using an optimized reaction condition. This protocol provide researchers with a rapid, efficient and cost-effective method for the construction of miRNA profiles from plant tissues containing low amounts of total RNA, such as fruit flesh and senescent leaves.
  2. Redwan RM, Saidin A, Kumar SV
    DNA Res, 2016 Oct 01;23(5):427-439.
    PMID: 27374615 DOI: 10.1093/dnares/dsw026
    The introduction of the elite pineapple variety, MD-2, has caused a significant market shift in the pineapple industry. Better productivity, overall increased in fruit quality and taste, resilience to chilled storage and resistance to internal browning are among the key advantages of the MD-2 as compared with its previous predecessor, the Smooth Cayenne. Here, we present the genome sequence of the MD-2 pineapple (Ananas comosus (L.) Merr.) by using the hybrid sequencing technology from two highly reputable platforms, i.e. the PacBio long sequencing reads and the accurate Illumina short reads. Our draft genome achieved 99.6% genome coverage with 27,017 predicted protein-coding genes while 45.21% of the genome was identified as repetitive elements. Furthermore, differential expression of ripening RNASeq library of pineapple fruits revealed ethylene-related transcripts, believed to be involved in regulating the process of non-climacteric pineapple fruit ripening. The MD-2 pineapple draft genome serves as an example of how a complex heterozygous genome is amenable to whole genome sequencing by using a hybrid technology that is both economical and accurate. The genome will make genomic applications more feasible as a medium to understand complex biological processes specific to pineapple.
  3. Redwan RM, Saidin A, Kumar SV
    BMC Plant Biol, 2015;15:196.
    PMID: 26264372 DOI: 10.1186/s12870-015-0587-1
    Pineapple (Ananas comosus var. comosus) is known as the king of fruits for its crown and is the third most important tropical fruit after banana and citrus. The plant, which is indigenous to South America, is the most important species in the Bromeliaceae family and is largely traded for fresh fruit consumption. Here, we report the complete chloroplast sequence of the MD-2 pineapple that was sequenced using the PacBio sequencing technology.
  4. Ong WD, Voo CL, Kumar SV
    Mol Biol Rep, 2012 May;39(5):5889-96.
    PMID: 22207174 DOI: 10.1007/s11033-011-1400-3
    Improving the quality of the non-climacteric fruit, pineapple, is possible with information on the expression of genes that occur during the process of fruit ripening. This can be made known though the generation of partial mRNA transcript sequences known as expressed sequence tags (ESTs). ESTs are useful not only for gene discovery but also function as a resource for the identification of molecular markers, such as simple sequence repeats (SSRs). This paper reports on firstly, the construction of a normalized library of the mature green pineapple fruit and secondly, the mining of EST-SSRs markers using the newly obtained pineapple ESTs as well as publically available pineapple ESTs deposited in GenBank. Sequencing of the clones from the EST library resulted in 282 good sequences. Assembly of sequences generated 168 unique transcripts (UTs) consisting of 34 contigs and 134 singletons with an average length of ≈500 bp. Annotation of the UTs categorized the known proteins transcripts into the three ontologies as: molecular function (34.88%), biological process (38.43%), and cellular component (26.69%). Approximately 7% (416) of the pineapple ESTs contained SSRs with an abundance of trinucleotide SSRs (48.3%) being identified. This was followed by dinucleotide and tetranucleotide SSRs with frequency of 46 and 57%, respectively. From these EST-containing SSRs, 355 (85.3%) matched to known proteins while 133 contained flanking regions for primer design. Both the ESTs were sequenced and the mined EST-SSRs will be useful in the understanding of non-climacteric ripening and the screening of biomarkers linked to fruit quality traits.
  5. Mokhtar MA, Normah MN, Kumar SV, Baharum SN
    Genet. Mol. Res., 2011;10(2):885-8.
    PMID: 21644205 DOI: 10.4238/vol10-2gmr1117
    Epinephelus fuscoguttatus is a commercially important marine fish species in southeast Asia. Due to overfishing and water pollution, this species has been declared as near-threatened. Thus, to provide information to help maintain and preserve the species, microsatellites were developed, using an enriched genomic library method. Thirty individuals were collected from the hatchery of the Fishery Research Institute, Terengganu, Malaysia. These individuals, from four to six years old, originated from Sabah and are maintained in captive culture as broodstock. Genomic DNA was extracted from the fins of selected individuals that weighed 3-8 kg. Ten microsatellite loci were found to be polymorphic in this population, with 5 to 21 alleles per locus. Observed and expected heterozygosities ranged from 0.53 to 0.97 and 0.59 to 0.95, respectively. Only one locus deviated significantly from Hardy-Weinberg equilibrium and no significant linkage disequilibrium was found among the pairs of loci. These polymorphic microsatellite loci will be used by the Malaysian Fishery Research Institute for investigating genetic diversity and for developing breeding strategies.
  6. Abdullah MA, Abdullah SM, Kumar SV, Hoque MZ
    Hematol Rep, 2019 Sep 18;11(3):8167.
    PMID: 31579124 DOI: 10.4081/hr.2019.8167
    A 3-year-old male child was presented with worsening abdominal pain, abdominal distension, lethargy, pallor and hepatosplenomegaly. The patient had multiple outpatient visits in the past and was treated with oral antibiotics, oral anthelmintic agents, albeit with minimal benefit. The patient also had non-neutropenic pyrexia spikes and oral ulcers. The patient was an adopted child; hence details about his biological parents' previous history were unclear. Differential diagnosis of Chronic Myelomonocytic Leukemia (CMML), Juvenile Myelomonocytic Leukemia (JMML), Gaucher's disease, Thalassemia and discrete pancreatic pathology was considered. Hemoglobin electrophoresis was indicative of thalassemia. Also, molecular detection method by polymerase chain reaction confirms a concurrent infection with Plasmodium knowlesi malaria. The BCR-ABL fusion gene was found to be negative. Correlating with peripheral monocytosis, bone marrow aspiration and trephine biopsy with blasts only 3-4% and hepatosplenomegaly, a diagnosis of JMML was established. We present a rare phenomenon with an overlap of signs and symptoms between JMML, underlying thalassemia, and Plasmodium knowlesi, posing a diagnostic challenge to physicians.
  7. Eu CS, Kumar SV, Ali S, Hassan SK
    Saudi J Anaesth, 2017 2 22;11(1):86-88.
    PMID: 28217061 DOI: 10.4103/1658-354X.197333
    The usage of epidural infusion for intraoperative and postoperative pain relief is widely used in certain pediatric anesthetic practice because of the effectiveness and advantages. However, there is drawback for these techniques due to its potential complications such as inadvertent intrathecal placement, local anesthetic toxicity, catheter migration, infection, and breakage of epidural catheter. Though occur infrequently, epidural catheters have been known to snap during insertion or removal. The retained catheter tip may lead to multiple complications, including nerve injury, infection, and even catheter migration. Although there are literatures recommend options for management of removal of retained catheter, there are limited reports of these occurrences, especially among children. We report a case of sequestrated sheared epidural catheter segment in a child, aiming to share this experience for the future management of patients under similar condition.
  8. Robert R, Rodrigues KF, Waheed Z, Kumar SV
    PMID: 29521145 DOI: 10.1080/24701394.2018.1448080
    This study is aimed at establishing a baseline on the genetic diversity of the Acropora corals of Sabah, North Borneo based on variations in the partial COI and CYB nucleotide sequences. Comparison across 50 shallow-water Acropora morphospecies indicated that the low substitution rates in the two genes were due to negative selection and that rate heterogeneity between them was asymmetric. CYB appeared to have evolved faster than COI in the Acropora as indicated by differences in the rate of pairwise genetic distance, degrees of transition bias (Ts/Tv), synonymous-to-nonsynonymous rate ratio (dN/dS), and substitution patterns at the three codon positions. Despite the relatively high haplotype diversity (Hd), nucleotide diversity (π) of the haplotype datasets was low due to stringent purifying selection operating on the genes. Subsequently, we identified individual COI and CYB haplotypes that were each extensively shared across sympatrically and allopatrically distributed Indo-Pacific Acropora. These reciprocally common mtDNA types were suspected to be ancestral forms of the genes whereas other haplotypes have mostly evolved from autoapomorphic mutations which have not been fixed within the species even though they are selectively neutral. To our knowledge, this is the first report on DNA barcodes of Acropora species in North Borneo and this understanding will play an important role in the management and conservation of these important reef-building corals.
  9. Yusuf NH, Ong WD, Redwan RM, Latip MA, Kumar SV
    Gene, 2015 Oct 15;571(1):71-80.
    PMID: 26115767 DOI: 10.1016/j.gene.2015.06.050
    MicroRNAs (miRNAs) are a class of small, endogenous non-coding RNAs that negatively regulate gene expression, resulting in the silencing of target mRNA transcripts through mRNA cleavage or translational inhibition. MiRNAs play significant roles in various biological and physiological processes in plants. However, the miRNA-mediated gene regulatory network in pineapple, the model tropical non-climacteric fruit, remains largely unexplored. Here, we report a complete list of pineapple mature miRNAs obtained from high-throughput small RNA sequencing and precursor miRNAs (pre-miRNAs) obtained from ESTs. Two small RNA libraries were constructed from pineapple fruits and leaves, respectively, using Illumina's Solexa technology. Sequence similarity analysis using miRBase revealed 579,179 reads homologous to 153 miRNAs from 41 miRNA families. In addition, a pineapple fruit transcriptome library consisting of approximately 30,000 EST contigs constructed using Solexa sequencing was used for the discovery of pre-miRNAs. In all, four pre-miRNAs were identified (MIR156, MIR399, MIR444 and MIR2673). Furthermore, the same pineapple transcriptome was used to dissect the function of the miRNAs in pineapple by predicting their putative targets in conjunction with their regulatory networks. In total, 23 metabolic pathways were found to be regulated by miRNAs in pineapple. The use of high-throughput sequencing in pineapples to unveil the presence of miRNAs and their regulatory pathways provides insight into the repertoire of miRNA regulation used exclusively in this non-climacteric model plant.
  10. Subramaniam R, Siddiquee S, Aguol KA, Hoque MZ, Kumar SV
    Data Brief, 2019 Apr;23:103796.
    PMID: 31372442 DOI: 10.1016/j.dib.2019.103796
    Members of the genus Tinctoporellus, which belong to the wood-degrading basidiomycetes, possess the ability to synthesize an array of industrially potent enzymes and metabolites. Here, we present the draft genome sequence of the species Tinctoporellus epimiltinus strain RS1, which is the first to represent its genus. The genome was sequenced using Illumina's 2 × 150 bp paired-end Nextera protocol. The draft genome assembly was 46.2 Mb in size consisting of 13,791 protein coding genes. Identification of carbohydrate active enzymes and laccases from the data may be useful in order to harness the metabolic potentials of the fungi. The data can be accessed at ENA under the accession number FTLJ00000000.
  11. Robert R, Lee DJ, Rodrigues KF, Hussein MA, Waheed Z, Kumar SV
    Zootaxa, 2016 Nov 29;4200(2):zootaxa.4200.2.2.
    PMID: 27988618 DOI: 10.11646/zootaxa.4200.2.2
    Acropora is the most biologically diverse group of reef-building coral, and its richness peaks at the Indo-Malay-Philippine Archipelago, the centre of global coral reef biodiversity. In this paper, we describe the species richness of Acropora fauna of North Borneo, East Malaysia, based on review of literature and as corroborated by voucher specimens. Eighty-three species of Acropora are reported here; four species are literature based and 79 are supported by voucher specimens that were subsequently photographed. New records for North Borneo were recorded for 12 species, including Acropora suharsonoi Wallace 1994 that was previously thought to be confined to a few islands along Lombok Strait, Indonesia. The diversity of Acropora in North Borneo is comparable to that of Indonesia and the Philippines, despite the area's smaller reef areas. This further reinforces its inclusion as part the global hotspot of coral biodiversity.
  12. Nurdalila AA, Bunawan H, Kumar SV, Rodrigues KF, Baharum SN
    Int J Mol Sci, 2015 Jul 02;16(7):14884-900.
    PMID: 26147421 DOI: 10.3390/ijms160714884
    Taxonomic confusion exists within the genus Epinephelus due to the lack of morphological specializations and the overwhelming number of species reported in several studies. The homogenous nature of the morphology has created confusion in the Malaysian Marine fish species Epinephelus fuscoguttatus and Epinephelus hexagonatus. In this study, the partial DNA sequence of the 16S gene and mitochondrial nucleotide sequences of two gene regions, Cytochrome Oxidase Subunit I and III were used to investigate the phylogenetic relationship between them. In the phylogenetic trees, E. fuscoguttatus was monophyletic with E. hexagonatus species and morphology examination shows that no significant differences were found in the morphometric features between these two taxa. This suggests that E. fuscoguttatus is not distinguishable from E. hexagonatus species, and that E. fuscoguttatus have been identified to be E. hexagonatus species is likely attributed to differences in environment and ability to camouflage themselves under certain conditions. Interestingly, this finding was also supported by Principal Component Analysis on Attenuated Total Reflectance-Fourier-transform Infrared (ATR-FTIR) data analysis. Molecular, morphological and meristic characteristics were combined with ATR-FTIR analysis used in this study offer new perspectives in fish species identification. To our knowledge, this is the first report of an extensive genetic population study of E. fuscoguttatus in Malaysia and this understanding will play an important role in informing genetic stock-specific strategies for the management and conservation of this highly valued fish.
  13. Lee J, Hughes T, Lee MH, Field H, Rovie-Ryan JJ, Sitam FT, et al.
    Ecohealth, 2020 09;17(3):406-418.
    PMID: 33226526 DOI: 10.1007/s10393-020-01503-x
    The legal and illegal trade in wildlife for food, medicine and other products is a globally significant threat to biodiversity that is also responsible for the emergence of pathogens that threaten human and livestock health and our global economy. Trade in wildlife likely played a role in the origin of COVID-19, and viruses closely related to SARS-CoV-2 have been identified in bats and pangolins, both traded widely. To investigate the possible role of pangolins as a source of potential zoonoses, we collected throat and rectal swabs from 334 Sunda pangolins (Manis javanica) confiscated in Peninsular Malaysia and Sabah between August 2009 and March 2019. Total nucleic acid was extracted for viral molecular screening using conventional PCR protocols used to routinely identify known and novel viruses in extensive prior sampling (> 50,000 mammals). No sample yielded a positive PCR result for any of the targeted viral families-Coronaviridae, Filoviridae, Flaviviridae, Orthomyxoviridae and Paramyxoviridae. In the light of recent reports of coronaviruses including a SARS-CoV-2-related virus in Sunda pangolins in China, the lack of any coronavirus detection in our 'upstream' market chain samples suggests that these detections in 'downstream' animals more plausibly reflect exposure to infected humans, wildlife or other animals within the wildlife trade network. While confirmatory serologic studies are needed, it is likely that Sunda pangolins are incidental hosts of coronaviruses. Our findings further support the importance of ending the trade in wildlife globally.
  14. Yew CW, Lu D, Deng L, Wong LP, Ong RT, Lu Y, et al.
    Hum Genet, 2018 Feb;137(2):161-173.
    PMID: 29383489 DOI: 10.1007/s00439-018-1869-0
    Southeast Asia (SEA) is enriched with a complex history of peopling. Malaysia, which is located at the crossroads of SEA, has been recognized as one of the hubs for early human migration. To unravel the genomic complexity of the native inhabitants of Malaysia, we sequenced 12 samples from 3 indigenous populations from Peninsular Malaysia and 4 native populations from North Borneo to a high coverage of 28-37×. We showed that the Negritos from Peninsular Malaysia shared a common ancestor with the East Asians, but exhibited some level of gene flow from South Asia, while the North Borneo populations exhibited closer genetic affinity towards East Asians than the Malays. The analysis of time of divergence suggested that ancestors of Negrito were the earliest settlers in the Malay Peninsula, whom first separated from the Papuans ~ 50-33 thousand years ago (kya), followed by East Asian (~ 40-15 kya), while the divergence time frame between North Borneo and East Asia populations predates the Austronesian expansion period implies a possible pre-Neolithic colonization. Substantial Neanderthal ancestry was confirmed in our genomes, as was observed in other East Asians. However, no significant difference was observed, in terms of the proportion of Denisovan gene flow into these native inhabitants from Malaysia. Judging from the similar amount of introgression in the Southeast Asians and East Asians, our findings suggest that the Denisovan gene flow may have occurred before the divergence of these populations and that the shared similarities are likely an ancestral component.
  15. Yew CW, Hoque MZ, Pugh-Kitingan J, Minsong A, Voo CLY, Ransangan J, et al.
    Ann. Hum. Genet., 2018 07;82(4):216-226.
    PMID: 29521412 DOI: 10.1111/ahg.12246
    The region of northern Borneo is home to the current state of Sabah, Malaysia. It is located closest to the southern Philippine islands and may have served as a viaduct for ancient human migration onto or off of Borneo Island. In this study, five indigenous ethnic groups from Sabah were subjected to genome-wide SNP genotyping. These individuals represent the "North Borneo"-speaking group of the great Austronesian family. They have traditionally resided in the inland region of Sabah. The dataset was merged with public datasets, and the genetic relatedness of these groups to neighboring populations from the islands of Southeast Asia, mainland Southeast Asia and southern China was inferred. Genetic structure analysis revealed that these groups formed a genetic cluster that was independent of the clusters of neighboring populations. Additionally, these groups exhibited near-absolute proportions of a genetic component that is also common among Austronesians from Taiwan and the Philippines. They showed no genetic admixture with Austro-Melanesian populations. Furthermore, phylogenetic analysis showed that they are closely related to non-Austro-Melansian Filipinos as well as to Taiwan natives but are distantly related to populations from mainland Southeast Asia. Relatively lower heterozygosity and higher pairwise genetic differentiation index (FST ) values than those of nearby populations indicate that these groups might have experienced genetic drift in the past, resulting in their differentiation from other Austronesians. Subsequent formal testing suggested that these populations have received no gene flow from neighboring populations. Taken together, these results imply that the indigenous ethnic groups of northern Borneo shared a common ancestor with Taiwan natives and non-Austro-Melanesian Filipinos and then isolated themselves on the inland of Sabah. This isolation presumably led to no admixture with other populations, and these individuals therefore underwent strong genetic differentiation. This report contributes to addressing the paucity of genetic data on representatives from this strategic region of ancient human migration event(s).
  16. Deng L, Lou H, Zhang X, Thiruvahindrapuram B, Lu D, Marshall CR, et al.
    BMC Genomics, 2019 Nov 12;20(1):842.
    PMID: 31718558 DOI: 10.1186/s12864-019-6226-8
    BACKGROUND: Recent advances in genomic technologies have facilitated genome-wide investigation of human genetic variations. However, most efforts have focused on the major populations, yet trio genomes of indigenous populations from Southeast Asia have been under-investigated.

    RESULTS: We analyzed the whole-genome deep sequencing data (~ 30×) of five native trios from Peninsular Malaysia and North Borneo, and characterized the genomic variants, including single nucleotide variants (SNVs), small insertions and deletions (indels) and copy number variants (CNVs). We discovered approximately 6.9 million SNVs, 1.2 million indels, and 9000 CNVs in the 15 samples, of which 2.7% SNVs, 2.3% indels and 22% CNVs were novel, implying the insufficient coverage of population diversity in existing databases. We identified a higher proportion of novel variants in the Orang Asli (OA) samples, i.e., the indigenous people from Peninsular Malaysia, than that of the North Bornean (NB) samples, likely due to more complex demographic history and long-time isolation of the OA groups. We used the pedigree information to identify de novo variants and estimated the autosomal mutation rates to be 0.81 × 10- 8 - 1.33 × 10- 8, 1.0 × 10- 9 - 2.9 × 10- 9, and ~ 0.001 per site per generation for SNVs, indels, and CNVs, respectively. The trio-genomes also allowed for haplotype phasing with high accuracy, which serves as references to the future genomic studies of OA and NB populations. In addition, high-frequency inherited CNVs specific to OA or NB were identified. One example is a 50-kb duplication in DEFA1B detected only in the Negrito trios, implying plausible effects on host defense against the exposure of diverse microbial in tropical rainforest environment of these hunter-gatherers. The CNVs shared between OA and NB groups were much fewer than those specific to each group. Nevertheless, we identified a 142-kb duplication in AMY1A in all the 15 samples, and this gene is associated with the high-starch diet. Moreover, novel insertions shared with archaic hominids were identified in our samples.

    CONCLUSION: Our study presents a full catalogue of the genome variants of the native Malaysian populations, which is a complement of the genome diversity in Southeast Asians. It implies specific population history of the native inhabitants, and demonstrated the necessity of more genome sequencing efforts on the multi-ethnic native groups of Malaysia and Southeast Asia.

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