Displaying publications 1 - 20 of 97 in total

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  1. Genetic diversity of Asian water buffalo (Bubalus bubalis): mitochondrial DNA D-loop and cytochrome b sequence variation
    Lau CH, Drinkwater RD, Yusoff K, Tan SG, Hetzel DJ, Barker JS
    Anim. Genet., 1998 Aug;29(4):253-64.
    PMID: 9745663
    Swamp and river buffalo mitochondrial DNA (mtDNA) was sequenced for 303 bp of the cytochrome b gene for 54 animals from 14 populations, and for 158 bp of the D-loop region for 80 animals from 11 populations. Only one cytochrome b haplotype was found in river buffalo. Of the four haplotypes identified in swamp buffalo, one found in all populations is apparently ancestral both to the other swamp haplotypes and to the river haplotype. The phylogenetic relationships among the 33 D-loop haplotypes, with a cluster of 11 found in swamp buffalo only, also support the evolution of domesticated swamp and river buffalo from an ancestral swamp-like animal, most likely represented today by the wild Asian buffalo (Bubalus arnee). The time of divergence of the swamp and river types, estimated from the D-loop data, is 28,000 to 87,000 years ago. We hypothesise that the species originated in mainland south-east Asia, and that it spread north to China and west to the Indian subcontinent, where the rive type evolved and was domesticated. Following domestication in China, the domesticated swamp buffalo spread through two separate routes, through Taiwan and the Philippines to the eastern islands of Borneo and Sulawesi, and south through mainland south-east Asia and then to the western islands of Indonesia.
  2. Population structure of the Southeast Asian river catfish Mystus nemurus
    Usmani S, Tan SG, Siraj SS, Yusoff K
    Anim. Genet., 2003 Dec;34(6):462-4.
    PMID: 14687079
    A total of 143 microsatellites were isolated from Mystus nemurus using a 5' anchored polymerase chain reaction technique or the random amplified hybridization microsatellite method, the first set of microsatellite markers developed for the Southeast Asian river catfish. Twenty polymorphic microsatellite loci were used as markers for population characterization of M. nemurus from six different geographical locations in Malaysia (Perak, Kedah, Johor, UPM, Sarawak and Terengganu). The number of alleles per locus ranged from 2 to 11 with 6.3 as the average number of alleles per locus. Characterization of the populations showed relatively high levels of genetic variation compared with previous studies using allozyme markers. The highest genetic similarity was found between Perak and Kedah, while the highest genetic distance was found between Terengganu and Kedah. The majority of clustering was in accordance with geographical locations and the histories of the populations. Microsatellite analysis indicated that the Sarawak population might be genetically closer to the Peninsular Malaysian populations than has been previously shown by other molecular marker studies.
  3. Fulltext Microsatellite Characterization of Malaysian Mahseer (Tor spp.) for Improvement of Broodstock Management and Utilization
    Chew PC, Christianus A, Zudaidy JM, Ina-Salwany MY, Chong CM, Tan SG
    Animals (Basel), 2021 Sep 08;11(9).
    PMID: 34573599 DOI: 10.3390/ani11092633
    In this study, a mixture of Tor tambra and T. tambroides with unknown genetic background were collected from 11 localities in Malaysia for broodstock development and sperm cryo-banking. This study aims to assess the microsatellite (simple sequence repeat, SSR) variation, genetic diversity, genetic differentiation, level of gene flow, population structure, genetic relatedness and their demographic aspects among these Tor populations, in addition to establishing their SSR profile by employing 22 SSR markers via fragment analysis. Total genomic DNA was extracted from 181 samples (91 cryopreserved milt samples and 90 scale samples of live broodfish). Results showed the Tor spp. collection retained their genetic variation but exhibited excessive homozygosity among individuals within population. Moderate genetic differentiation was shown among the populations, with highly significant (p < 0.001) fixation indices (FST, FIS and FIT). A low gene flow over all loci (Nm 1.548) indicates little genetic variation transfer between populations. The genetic structures of all the populations were successfully resolved into four main clusters by an unweighted pair group method with arithmetic mean (UPGMA) dendrogram generated based on Nei's genetic distances. The population structures based on principal coordinates analysis (PCoA) and the Bayesian model also suggested four distinct clusters following geographical regions and eight closely related populations. This study provided a useful baseline reference for better genetic management and utilization of the Tor spp. stocks in their breeding and conservation programmes.
  4. Genetic markers in a Malaysian population: variants of uridine monophosphate kinase (UMPK), phosphoglycolate phosphatase (PGP) and pancreatic amylase (AMY2)
    Zarinah KH, Abdullah F, Tan SG
    Ann Hum Biol, 1984 11 1;11(6):533-6.
    PMID: 6084457
    Three genetic markers, red-cell UMPK, PGP and serum AMY2 were investigated in Malaysians of Malay, Chinese and Indian ancestries using starch-gel and agarose-gel electrophoresis. UMPK was found to be polymorphic in all three races. Variants were observed for PGP in Malays; in Indians it is a polymorphic marker whereas it is monomorphic in Chinese. AMY2 was polymorphic only in Indians. The UMPK1 frequencies in Malays, Chinese and Indians, respectively, are 0.851, 0.880 and 0.942. The PGP1 frequencies are 0.991, 1.000, 0.962, and the AMY1(2) frequencies are 1.000, 1.000 and 0.983.
  5. Fulltext Mapping quantitative trait loci (QTLs) for fatty acid composition in an interspecific cross of oil palm
    Singh R, Tan SG, Panandam JM, Rahman RA, Ooi LC, Low ET, et al.
    BMC Plant Biol, 2009;9:114.
    PMID: 19706196 DOI: 10.1186/1471-2229-9-114
    Marker Assisted Selection (MAS) is well suited to a perennial crop like oil palm, in which the economic products are not produced until several years after planting. The use of DNA markers for selection in such crops can greatly reduce the number of breeding cycles needed. With the use of DNA markers, informed decisions can be made at the nursery stage, regarding which individuals should be retained as breeding stock, which are satisfactory for agricultural production, and which should be culled. The trait associated with oil quality, measured in terms of its fatty acid composition, is an important agronomic trait that can eventually be tracked using molecular markers. This will speed up the production of new and improved oil palm planting materials.
  6. Fulltext The first Malay database toward the ethnic-specific target molecular variation
    Halim-Fikri H, Etemad A, Abdul Latif AZ, Merican AF, Baig AA, Annuar AA, et al.
    BMC Res Notes, 2015;8:176.
    PMID: 25925844 DOI: 10.1186/s13104-015-1123-y
    The Malaysian Node of the Human Variome Project (MyHVP) is one of the eighteen official Human Variome Project (HVP) country-specific nodes. Since its inception in 9(th) October 2010, MyHVP has attracted the significant number of Malaysian clinicians and researchers to participate and contribute their data to this project. MyHVP also act as the center of coordination for genotypic and phenotypic variation studies of the Malaysian population. A specialized database was developed to store and manage the data based on genetic variations which also associated with health and disease of Malaysian ethnic groups. This ethnic-specific database is called the Malaysian Node of the Human Variome Project database (MyHVPDb).
  7. Fulltext RNA sequencing of kidney and liver transcriptome obtained from wild cynomolgus macaque (Macaca fascicularis) originating from Peninsular Malaysia
    Ee Uli J, Yong CS, Yeap SK, Alitheen NB, Rovie-Ryan JJ, Mat Isa N, et al.
    BMC Res Notes, 2018 Dec 22;11(1):923.
    PMID: 30577850 DOI: 10.1186/s13104-018-4014-1
    OBJECTIVE: Using high-throughput RNA sequencing technology, this study aimed to sequence the transcriptome of kidney and liver tissues harvested from Peninsular Malaysia cynomolgus macaque (Macaca fascicularis). M. fascicularis are significant nonhuman primate models in the biomedical field, owing to the macaque's biological similarities with humans. The additional transcriptomic dataset will supplement the previously described Peninsular Malaysia M. fascicularis transcriptomes obtained in a past endeavour.

    RESULTS: A total of 75,350,240 sequence reads were obtained via Hi-seq 2500 sequencing technology. A total of 5473 significant differentially expressed genes were called. Gene ontology functional categorisation showed that cellular process, catalytic activity, and cell part categories had the highest number of expressed genes, while the metabolic pathways category possessed the highest number of expressed genes in the KEGG pathway analysis. The additional sequence dataset will further enrich existing M. fascicularis transcriptome assemblies, and provide a dataset for further downstream studies.

  8. Fulltext The effects of different velogenic NDV infections on the chicken bursa of Fabricius
    Kristeen-Teo YW, Yeap SK, Tan SW, Omar AR, Ideris A, Tan SG, et al.
    BMC Vet Res, 2017 May 31;13(1):151.
    PMID: 28569155 DOI: 10.1186/s12917-017-1071-y
    BACKGROUND: Virulent Newcastle disease virus (NDV) was reported to cause rapid depletion of chicken bursa of Fabricius. Severe pathological condition of the organ is commonly associated with high levels of virus replication, intense inflammatory response and also the degree of apoptosis. In this study, the responses of chicken bursa of Fabricius infected with two different strains of velogenic NDV, namely AF2240 and IBS002, were investigated by observing cell population changes, oxidative stress, viral replication and cytokine expression in the organ. Subsequently, apoptosis of enriched bursal IgM+ cells was determined to help us elucidate possible host pathogen relationships between the chicken bursa of Fabricius and NDV infection.

    RESULTS: The depletion of IgM+ cells and infiltration of macrophages were observed to be higher in bursa infected with AF2240 as compared to IBS002. In line with the increment of the macrophage population, higher nitric oxide (NO) and malondialdehyde (MDA) contents which indicated higher oxidative stress were also detected in bursa infected with NDV AF2240. In addition, higher pro-inflammatory cytokines and chemokine gene expression such as chicken CXCLi2, IL-18 and IFN-γ were observed in AF2240 infected bursa. Depletion of IgM+ cells was further confirmed with increased cell death and apoptosis of the cells in AF2240 infected bursa as compared to IBS002. However, it was found that the viral load for NDV strain IBS002 was comparatively higher than AF2240 although the magnitude of the pro- inflammatory cytokines expression and cell apoptosis was lower than AF2240.

    CONCLUSION: The results of our study demonstrated that infection of NDV strains AF2240 and IBS002 caused apoptosis in bursa IgM+ cells and its severity was associated with increased expression of pro-inflammatory cytokines/chemokine, macrophage infiltration and oxidative stress as the infection duration was prolonged. However, of the two viruses, we observed that NDV AF2240 induced a greater magnitude of apoptosis in chicken bursa IgM+ cells in comparison to IBS002. This might be due to the high level of oxidative stress and inflammatory cytokines/chemokine as well as lower IL10 expression which subsequently led to a high rate of apoptosis in the chicken bursa of Fabricius although the detected viral load of AF2240 was lower than IBS002.

  9. PCR cycle sequencing protocol for population mitochondrial cytochrome b analysis
    Lau CH, Yusoff K, Tan SG, Yamada Y
    Biotechniques, 1995 Feb;18(2):262-6.
    PMID: 7727128
    Laboratories intending to adopt cycle sequencing of PCR products in their routine analysis often face a confusing range of methods and kits. Through the study of mitochondrial cytochrome b, we have shown that clean and highly reproducible sequences could be obtained by using a combination of existing simple and economical methods in the preparation of DNA templates, PCR, purification of PCR products and sequencing. Our protocol is useful in itself or as a standard in typing other PCR-amplified DNA at the population level.
  10. Identification of hybrids of painted and milky storks using FTA card-collected blood, molecular markers, and morphologies
    Yee EY, Zainuddin ZZ, Ismail A, Yap CK, Tan SG
    Biochem Genet, 2013 Oct;51(9-10):789-99.
    PMID: 23846110 DOI: 10.1007/s10528-013-9607-8
    Suspicious hybrids of painted storks and milky storks were found in a Malaysian zoo. Blood of these birds was sampled on FTA cards for DNA fingerprinting. Of 44 optimized primers, 6 produced diagnostic markers that could identify hybrids. The markers were based on simple, direct PCR-generated multilocus banding patterns that provided two sets of genetic data, one for each of the two stork species and another for the hybrids. It also revealed that large DNA fragments (3,000 bp) could be amplified from blood collected on FTA cards. When the results of each individual bird's DNA fingerprint were compared with plumage characters, the hybrids were found to express a range of intermediate phenotypic traits of the pure breeds with no dominant plumage characteristic from either parental species.
  11. Morphological and genetic variations of the freshwater leech, Hirudinaria spp., in Peninsular Malaysia
    Chong LK, Ong AH, Tan SG, Taranjeet KA, Peris MM, Sana AM, et al.
    Biochem Genet, 2014 Jun;52(5-6):283-95.
    PMID: 24535156 DOI: 10.1007/s10528-014-9647-8
    In this study the genetic diversity of local freshwater leeches (Hirudinaria spp.) was inferred using mtDNA COI gene analysis and compared with the gross external variations of 26 freshwater leech specimens obtained from the wild and leech farms. Based on a neighbor-joining tree generated from 516 COI base sequences, four distinct clades of Hirudinaria were seen with interspecific genetic divergence in the range of 7.6-14.5%. The external morphological variations based on the presence of stripes, location of gonopores, and anus separated the samples into four morphologically distinct groups matching the four clades obtained from the molecular data. Two black stripes at the ventral region were observed only in specimens found clustered with clades that contained the GenBank-reported H. manillensis, whereas the brown or dark green coloration without stripes on the ventral region was seen in samples that clustered with H. javanica and H. bpling clades.
  12. Genetic studies of water buffalo blood markers. II. Carbonic anhydrase, esterase D, malate dehydrogenase, and malic enzyme
    Sreetharan K, Mukherjee TK, Tan SG, Selvaraj OS, Barker JS
    Biochem Genet, 1994 Feb;32(1-2):35-8.
    PMID: 8031293
  13. Genetic studies of water buffalo blood markers. I. Red cell acid phosphatase, albumin, catalase, red cell alpha-esterase-3, group-specific component, and protease inhibitor
    Tan SG, Barker JS, Selvaraj OS, Mukherjee TK, Wong YF
    Biochem Genet, 1993 Jun;31(5-6):223-30.
    PMID: 8259925
    We have developed the methodologies for typing and family studies to establish the modes of inheritance of water buffalo red cell acid phosphatase (Acp), protease inhibitor (Pi), and group-specific component (Gc) on isoelectric focusing and albumin (Alb), red cell alpha-esterase-3 (Est-3), and catalase (Cat) on polyacrylamide gel electrophoresis. Family studies showed that Pi, Gc, Alb, and Cat are coded by autosomal genes with two codominant alleles, while Est-3 is autosomal with two codominant alleles and a recessive null allele and Acp exhibits three codominant alleles.
  14. Interpopulation crosses, inheritance study, and genetic variability in the brown planthopper complex, Nilaparvata lugens (Homoptera: Delphacidae)
    Latif MA, Omar MY, Tan SG, Siraj SS, Ismail AR
    Biochem Genet, 2010 Apr;48(3-4):266-86.
    PMID: 19967400 DOI: 10.1007/s10528-009-9316-5
    Studies on hybridization, inheritance, and population genetics of brown planthoppers that infest rice and weeds were undertaken using starch gel electrophoresis to determine whether the weed-infesting population represents a biological race or a species. F(1) and F(2) generations were produced by crosses between parental insects from the two populations with little indication of hybrid sterility. Gpi, Mdh, and Idh loci were inherited in a simple Mendelian fashion in families of two sympatric populations. Sixteen populations of Nilaparvata spp. from eight locations were collected. The Mdh, Idh, Pgm, Gpi, 6Pgd, and Acp loci were polymorphic. The N. lugens of rice with high esterase activity were clustered into a group and characterized by the presence of alleles Gpi (110) and Gpi (120), whereas N. lugens from weeds with low esterase activity were clustered into another group and characterized by Gpi (100) and Gpi (90) . There was a lack of heterozygotes between the common alleles of the two populations. This means that the two groups of individuals belong to different gene pools.
  15. Development of microsatellite markers from an enriched genomic library for the genetic analysis of the Malaysian giant freshwater prawn, Macrobrachium rosenbergii
    See LM, Tan SG, Hassan R, Siraj SS, Bhassu S
    Biochem Genet, 2009 Oct;47(9-10):722-6.
    PMID: 19603264 DOI: 10.1007/s10528-009-9270-2
  16. The genetic structure of Oreochromis spp. (Tilapia) populations in Malaysia as revealed by microsatellite DNA analysis
    Bhassu S, Yusoff K, Panandam JM, Embong WK, Oyyan S, Tan SG
    Biochem Genet, 2004 Aug;42(7-8):217-29.
    PMID: 15487586
    The genetic make-up of five populations of Oreochromis spp. was examined by microsatellite analysis. Eleven polymorphic microsatellite loci showed significant departures from the Hardy-Weinberg equilibrium. The mean heterozygosity ranged from 0.6280 to 0.7040 for each population. The genetic distance values showed a clear separation between O. niloticus and O. mossambicus. The differentiation of the O. niloticus populations was then tested with various genetic measures, which are based on both the Infinite Allele and the Stepwise Mutation models. All these measures grouped the populations similarly.
  17. Identification and characterization of Malaysian river catfish, Mystus nemurus (C&V): RAPD and AFLP analysis
    Chong LK, Tan SG, Yusoff K, Siraj SS
    Biochem Genet, 2000 Apr;38(3-4):63-76.
    PMID: 11100266
    This work represents the first application of the amplified fragment length polymorphism (AFLP) technique and the random amplified polymorphic DNA (RAPD) technique in the study of genetic variation within and among five geographical populations of M. nemurus. Four AFLP primer combinations and nine RAPD primers detected a total of 158 and 42 polymorphic markers, respectively. The results of AFLP and RAPD analysis provide similar conclusions as far as the population clustering analysis is concerned. The Sarawak population, which is located on Borneo Island, clustered by itself and was thus isolated from the rest of the populations located in Peninsular Malaysia. Both marker systems revealed high genetic variability within the Universiti Putra Malaysia (UPM) and Sarawak populations. Three subgroups each from the Kedah, Perak, and Sarawak populations were detected by AFLP but not by RAPD. Unique AFLP fingerprints were also observed in some unusual genotypes sampled in Sarawak. This indicates that AFLP may be a more efficient marker system than RAPD for identifying genotypes within populations.
  18. Biochemical genetic studies on wild populations of three species of green leafhoppers, Nephotettix, from Peninsular Malaysia
    Tan SG, Omar MY, Mahani KW, Rahani M, Selvaraj OS
    Biochem Genet, 1994 Dec;32(11-12):415-22.
    PMID: 7748158
    Nine populations of three species of Nephotettix (Insecta: Hemiptera) from Peninsular Malaysia were analysed for nine enzymes comprising 11 loci. Nei's (Genetics 89, 583, 1978) genetic distance, D, between N. virescens and N. malayanus was 0.181, that between N. virescens and N. nigropictus was 0.283, and that between N. malayanus and N. nigropictus was 0.203. The genetic distance between N. nigropictus from rice plant and from the weed-grass L. hexandra at Universiti Pertanian Malaysia was 0.004 and their genetic identity was 0.996, thus indicating that this insect species fees on both host plants. The proportion of polymorphic loci and the observed heterozygosities were higher in N. nigropictus, with a wider range of host plants, than in N. virescens and N. malayanus, restricted to rice and L. hexandra, respectively.
  19. Virus-like particle of Macrobrachium rosenbergii nodavirus produced in Spodoptera frugiperda (Sf9) cells is distinctive from that produced in Escherichia coli
    Kueh CL, Yong CY, Masoomi Dezfooli S, Bhassu S, Tan SG, Tan WS
    Biotechnol Prog, 2017 Mar;33(2):549-557.
    PMID: 27860432 DOI: 10.1002/btpr.2409
    Macrobrachium rosenbergii nodavirus (MrNV) is a virus native to giant freshwater prawn. Recombinant MrNV capsid protein has been produced in Escherichia coli, which self-assembled into virus-like particles (VLPs). However, this recombinant protein is unstable, degrading and forming heterogenous VLPs. In this study, MrNV capsid protein was produced in insect Spodoptera frugiperda (Sf9) cells through a baculovirus system. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed that the recombinant protein produced by the insect cells self-assembled into highly stable, homogenous VLPs each of approximately 40 nm in diameter. Enzyme-linked immunosorbent assay (ELISA) showed that the VLPs produced in Sf9 cells were highly antigenic and comparable to those produced in E. coli. In addition, the Sf9 produced VLPs were highly stable across a wide pH range (2-12). Interestingly, the Sf9 produced VLPs contained DNA of approximately 48 kilo base pairs and RNA molecules. This study is the first report on the production and characterization of MrNV VLPs produced in a eukaryotic system. The MrNV VLPs produced in Sf9 cells were about 10 nm bigger and had a uniform morphology compared with the VLPs produced in E. coli. The insect cell production system provides a good source of MrNV VLPs for structural and immunological studies as well as for host-pathogen interaction studies. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:549-557, 2017.
  20. Mercury levels in the green-lipped mussel Perna viridis (Linnaeus) from the west coast of peninsular Malaysia
    Yap CK, Ismail A, Tan SG
    Bull Environ Contam Toxicol, 2003 Sep;71(3):570-6.
    PMID: 14567584
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