Grain weight is a major component of rice grain yield and is controlled by quantitative trait loci. Previously, a rice grain weight quantitative trait locus (qGW6) was detected near marker RM587 on chromosome 6 in a backcross population (BC2F2) derived from a cross between Oryza rufipogon IRGC105491 and O. sativa cv. MR219. Using a BC2F5 population, qGW6 was validated and mapped to a region of 4.8 cM (1.2 Mb) in the interval between RM508 and RM588. Fine mapping using a series of BC4F3 near isogenic lines further narrowed the interval containing qGW6 to 88 kb between markers RM19268 and RM19271.1. According to the Duncan multiple range test, 8 BC4F4 near isogenic lines had significantly higher 100-grain weight (4.8 to 7.5% over MR219) than their recurrent parent, MR219 (P < 0.05). According to the rice genome automated annotation database, there are 20 predicted genes in the 88-kb target region, and 9 of them have known functions. Among the genes with known functions in the target region, in silico gene expression analysis showed that 9 were differentially expressed during the seed development stage(s) from gene expression series GSE6893; however, only 3 of them have known functions. These candidates provide targets for further characterization of qGW6, which will assist in understanding the genetic control of grain weight in rice.
The genus Curcuma is a member of the ginger family (Zingiberaceae) that has recently become popular for use as flowering pot plants, both indoors and as patio and landscape plants. We used PCR-based molecular markers (SSRs) to elucidate genetic variation and relationships between five varieties of Curcuma (Curcuma alismatifolia) cultivated in Malaysia. Of the primers tested, 8 (of 17) SSR primers were selected for their reproducibility and high rates of polymorphism. The number of presumed alleles revealed by the SSR analysis ranged from two to six alleles, with a mean value of 3.25 alleles per locus. The values of HO and HE ranged from 0 to 0.8 (mean value of 0.2) and 0.1837 to 0.7755 (mean value of 0.5102), respectively. Eight SSR primers yielded 26 total amplified fragments and revealed high rates of polymorphism among the varieties studied. The polymorphic information content varied from 0.26 to 0.73. Dice's similarity coefficient was calculated for all pairwise comparisons and used to construct an unweighted pair group method with arithmetic average (UPGMA) dendrogram. Similarity coefficient values from 0.2105 to 0.6667 (with an average of 0.4386) were found among the five varieties examined. A cluster analysis of data using a UPGMA algorithm divided the five varieties/hybrids into 2 groups.
This study was directed at the understanding of the function of CCoAOMT isolated from Acacia auriculiformis x Acacia mangium. Full length cDNA of the Acacia hybrid CCoAOMT (AhCCoAOMT) was 1024-bp long, containing 750-bp coding regions, with one major open reading frame of 249 amino acids. On the other hand, full length genomic sequence of the CCoAOMT (AhgflCCoAOMT) was 2548 bp long, containing three introns and four exons with a 5' untranslated region (5'UTR) of 391 bp in length. The 5'UTR of the characterized CCoAOMT gene contains various regulatory elements. Southern analysis revealed that the Acacia hybrid has more than three copies of the CCoAOMT gene. Real-time PCR showed that this gene was expressed in root, inner bark, leaf, flower and seed pod of the Acacia hybrid. Downregulation of the homologous CCoAOMT gene in tobacco by antisense (AS) and intron-containing hairpin (IHP) constructs containing partial AhCCoAOMT led to reduction in lignin content. Expression of the CCoAOMT in AS line (pART-HAS78-03) and IHP line (pART-HIHP78-06) was reduced respectively by 37 and 75% compared to the control, resulting in a decrease in the estimated lignin content by 24 and 56%, respectively. AhCCoAOMT was found to have altered not only S and G units but also total lignin content, which is of economic value to the pulp industry. Subsequent polymorphism analysis of this gene across eight different genetic backgrounds each of A. mangium and A. auriculiformis revealed 47 single nucleotide polymorphisms (SNPs) in A. auriculiformis CCoAOMT and 30 SNPs in A. mangium CCoAOMT.
For centuries, morphology-based fish identification has been applied without molecular evaluation. Many studies showed that specimens with a similar morphology are frequently found to be quite genetically distinct. One of the fish species that still remains taxonomically problematic is a commercial snapper species, Lutjanus johnii. Because of morphological ambiguities among local fish taxonomists in Malaysia, we examined the ability of the cytochrome oxidase I (COI) gene to genetically examine the taxonomic status of L. johnii. A 626-base pair COI region was successfully amplified and aligned with conspecific sequences that were retrieved from GenBank. The phylogenetic tree obtained showed two major clusters; the first cluster consists of L. johnii from Straits of Malacca, Thailand, Australia, and China while the second cluster comprises L. johnii from China and India. The latter group showed sequence divergence greater than 3.5%. After observing this, we suspected that there might be a cryptic species between the South China Sea and Indian Ocean. This is the first molecular report concerning the commercial species of snapper, L. johnii, in Malaysia, which had only gained provisional recognition from morphological examination.
The mosquito Aedes albopictus is indigenous to Southeast Asian and is a vector for arbovirus diseases. Studies examining the population genetics structure of A. albopictus have been conducted worldwide; however, there are no documented reports on the population genetic structure of A. albopictus in Malaysia, particularly in Penang. We examined the population genetics of A. albopictus based on a 445-base pair segment of the mitochondrial DNA cytochrome oxidase 1 gene among 77 individuals from 9 localities representing 4 regions (Seberang Perai Utara, Seberang Perai Tengah, Northeast, and Southwest) of Penang. A total of 37 haplotypes were detected, including 28 unique haplotypes. The other 9 haplotypes were shared among various populations. These shared haplotypes reflect the weak population genetic structure of A. albopictus. The phylogenetic tree showed a low bootstrap value with no genetic structure, which was supported by minimum spanning network analysis. Analysis of mismatch distribution showed poor fit of equilibrium distribution. The genetic distance showed low genetic variation, while pairwise FST values showed no significant difference between all regions in Penang except for some localities. High haplotype diversity and low nucleotide diversity was observed for cytochrome oxidase 1 mtDNA. We conclude that there is no population genetic structure of A. albopictus mosquitoes in the Penang area.
Growth factors are polypeptides that are critical for the initiation, progression, and metastasis of cancer. Most tumor cells are capable of synthesizing particular growth factors leading to constitutive pathway activation in these cells through autocrine signaling. Epidermal growth factor (EGF) is a potent mitogenic peptide that exerts direct effects on the proliferation and differentiation of tumor cells in carcinogenesis. By contrast, vascular endothelial growth factor (VEGF) is vital for the invasion and metastasis of neoplasms through the formation of new blood vessels from mature endothelial cells. In this study, we investigated the association between functional polymorphisms of both the EGF and VEGF genes and colorectal cancer (CRC) susceptibility. A total of 130 CRC patients and 212 healthy controls were recruited for this case-control study. Genotyping of genetic variants was conducted via real-time polymerase chain reaction (PCR) amplification with allele-specific TaqMan probes. None of the genotypes of the EGF +61 A>G and VEGF +936 C>T variants was significantly associated with CRC susceptibility among the Malaysian subjects evaluated (P > 0.05). The observed frequency distributions of the EGF +61 A>G polymorphism genotypes showed ethnic heterogeneity, which was not the case for the VEGF +936 C>T genotypes. In conclusion, no positive correlation between these functional polymorphisms and CRC risk was found in this Malaysian population. Studies of the EGF and VEGF genes and CRC susceptibility are scarce, and the results reported thus far differ from one population to another. Hence, more replication studies are warranted before any firm conclusions can be made.
Commercial flocks infected by Eimeria species parasites, including Eimeria maxima, have an increased risk of developing clinical or subclinical coccidiosis; an intestinal enteritis associated with increased mortality rates in poultry. Currently, infection control is largely based on chemotherapy or live vaccines; however, drug resistance is common and vaccines are relatively expensive. The development of new cost-effective intervention measures will benefit from unraveling the complex genetic mechanisms that underlie host-parasite interactions, including the identification and characterization of genes encoding proteins such as phosphatidylinositol 4-phosphate 5-kinase (PIP5K). We previously identified a PIP5K coding sequence within the E. maxima genome. In this study, we analyzed two bacterial artificial chromosome clones presenting a ~145-kb E. maxima (Weybridge strain) genomic region spanning the PIP5K gene locus. Sequence analysis revealed that ~95% of the simple sequence repeats detected were located within regions comparable to the previously described feature-rich segments of the Eimeria tenella genome. Comparative sequence analysis with the orthologous E. maxima (Houghton strain) region revealed a moderate level of conserved synteny. Unique segmental organizations and telomere-like repeats were also observed in both genomes. A number of incomplete transposable elements were detected and further scrutiny of these elements in both orthologous segments revealed interesting nesting events, which may play a role in facilitating genome plasticity in E. maxima. The current analysis provides more detailed information about the genome organization of E. maxima and may help to reveal genotypic differences that are important for expression of traits related to pathogenicity and virulence.
Calamus palustris Griff. is an economically important dioecious rattan species in Southeast Asia. However, dioecy and onset of flowering at 3-4 years old render uncertainties in desired female:male seedling ratios to establish a productive seed orchard for this rattan species. We constructed a subtractive library for male floral tissue to understand the genetic mechanism for gender determination in C. palustris. The subtractive library produced 1536 clones with 1419 clones of high quality. Reverse Northern screening showed 313 clones with differential expression, and sequence analyses clustered them into 205 unigenes, including 32 contigs and 173 singletons. The subtractive library was further validated with reverse transcription-quantitative polymerase chain reaction analysis. Homology identification classified the unigenes into 12 putative functional proteins with 83% unigenes showing significant match to proteins in databases. Functional annotations of these unigenes revealed genes involved in male flower development, including MADS-box genes, pollen-related genes, phytohormones for flower development, and male flower organ development. Our results showed that the male floral genes may play a vital role in sex determination in C. palustris. The identified genes can be exploited to understand the molecular basis of sex determination in C. palustris.
A genome-wide association study showed that the tagging single nucleotide polymorphism (SNP) rs7566605 in the insulin-induced gene 2 (INSIG2) was associated with obesity. Attempts to replicate this result in different populations have produced inconsistent findings. We aimed to study the association between the rs7566605 SNP with obesity and other metabolic parameters in Malaysian Malays. Anthropometric and obesity-related metabolic parameters and DNA samples were collected. We genotyped the rs7566605 polymorphism in 672 subjects using real-time polymerase chain reaction. No significant associations were found between the rs7566605 tagging SNP of INSIG2 with obesity or other metabolic parameters in the Malaysian Malay population. The INSIG2 rs7566605 SNP may not play a role in the development of obesity-related metabolic traits in Malaysian Malays.
Colorectal cancer (CRC) is one of the most common types of cancer in both developed and developing countries. This disease is triggered by and progresses via the sequential accumulation of multiple genetic alterations. In addition, the interaction between low-penetrance genes and environmental factors can also increase the risk of developing CRC. Since inflammatory bowel diseases (IBDs) are one of the predisposing factors for CRC, IBD-related genes might, to a certain extent, be associated with cancer initiation. The nucleotide oligomerization domain 2/caspase activating recruitment domain 15 gene (NOD2/CARD15) is the most well-established gene to be associated with increased susceptibility to Crohn's disease. Thus, various studies have been performed to investigate the potential contribution of this gene to CRC risk. In this study, we aimed to determine the frequency of the Arg702Trp, Gly908Arg, 3020insC, Pro268Ser, and JW1 variants of NOD2/CARD15, and to investigate their association with CRC susceptibility. A total of 130 CRC patients and 212 healthy controls were recruited for this study. Subsequently, real-time polymerase chain reaction with TaqMan was performed for the genotyping of these NOD2/ CARD15 variants. None of the NOD2/CARD15 variants was statistically associated to CRC susceptibility in our Malaysian population. Our findings were remarkably similar to those of other Asian cohorts, which indicated that these NOD2/CARD15 variants exhibit genetic heterogeneity between Caucasian and Asian populations.
Anthracnose caused by Colletotrichum species is a common postharvest disease of banana fruit. We investigated and identified Colletotrichum species associated with anthracnose in several local banana cultivars based on morphological characteristics and sequencing of ITS regions and of the β-tubulin gene. Thirty-eight Colletotrichum isolates were encountered in anthracnose lesions of five local banana cultivars, 'berangan', 'mas', 'awak', 'rastali', and 'nangka'. Based on morphological characteristics, 32 isolates were identified as Colletotrichum gloeosporioides and 6 isolates as C. musae. C. gloeosporioides isolates were divided into two morphotypes, with differences in colony color, shape of the conidia and growth rate. Based on ITS regions and β-tubulin sequences, 35 of the isolates were identified as C. gloeosporioides and only 3 isolates as C. musae; the percentage of similarity from BLAST ranged from 95-100% for ITS regions and 97-100% for β-tubulin. C. gloeosporioides isolates were more prevalent compared to C. musae. This is the first record of C. gloeosporioides associated with banana anthracnose in Malaysia. In a phylogenetic analysis of the combined dataset of ITS regions and β-tubulin using a maximum likelihood method, C. gloeosporioides and C. musae isolates were clearly separated into two groups. We concluded that C. gloeosporioides and C. musae isolates are associated with anthracnose in the local banana cultivars and that C. gloeosporioides is more prevalent than C. musae.
Bats are important flagship species for biodiversity research; however, diversity in Southeast Asia is considerably underestimated in the current checklists and field guides. Incorporation of DNA barcoding into surveys has revealed numerous species-level taxa overlooked by conventional methods. Inclusion of these taxa in inventories provides a more informative record of diversity, but is problematic as these species lack formal description. We investigated how frequently documented, but undescribed, bat taxa are encountered in Peninsular Malaysia. We discuss whether a barcode library provides a means of recognizing and recording these taxa across biodiversity inventories. Tissue was sampled from bats trapped at Pasir Raja, Dungun Terengganu, Peninsular Malaysia. The DNA was extracted and the COI barcode region amplified and sequenced. We identified 9 species-level taxa within our samples, based on analysis of the DNA barcodes. Six specimens matched to four previously documented taxa considered candidate species but currently lacking formal taxonomic status. This study confirms the high diversity of bats within Peninsular Malaysia (9 species in 13 samples) and demonstrates how DNA barcoding allows for inventory and documentation of known taxa lacking formal taxonomic status.
Copy number variation (CNV) is a form of genetic variation in addition to single nucleotide polymorphisms. The significance of CNV in the manifestation of a number of diseases is only recently receiving considerable attention. We genotyped 163 dengue patients from Peninsular Malaysia for genes possibly linked to dengue infection using quantitative real-time PCR. Here, we report a serendipitous discovery of a novel rare CNV of the ABCF1 gene among the dengue patients. Among these patients, two had a gain of 1 copy (CN = 3) and one had lost 1 copy (CN = 1), indicating that a rare CNV of the ABCF1 gene was detected among dengue patients from Peninsular Malaysia. Although the gene is suspected to regulate inflammatory responses and pathogen-induced cytokine storm, its relevance to dengue requires further investigation.
The genus Labisia (Myrsinaceae) is a popular medicinal plant in Malaysia. We examined the genetic relationship among three varieties of L. pumila var. pumila, L. pumila var. alata, L. pumila var. lanceolata and Labisia paucifolia using an ISSR assay. Fifty-eight primers were tested, among which 18 gave reliable polymorphic banding patterns; these yielded 264 polymorphic markers. A similarity matrix was used to construct a dendrogram, and a principal component plot was developed to examine genetic relationships among varieties. Jaccard's similarity coefficient among species ranged from 0.09 to 0.14. At a similarity of 0.117%, species were divided into two main clusters. The mean value of the observed number of alleles, the effective number of alleles, mean Nei's gene diversity, and Shannon's information index were 1.98, 1.64, 0.38, and 0.57, respectively.
Mutations in the PAX6 gene that cause aniridia have been identified in various ethnicities but not in the Malaysian population. Therefore, the objective of this study was to investigate the PAX6 mutation in a Malaysian family with congenital aniridia. In this study, a complete ophthalmic examination was performed on a Dusun ethnic family with aniridia. Genomic DNA was extracted from the peripheral blood of the subjects and screened for the PAX6 gene mutation using polymerase chain reaction amplification high-resolution melting curve analysis (PCR-HRM) followed by confirmation via direct DNA sequencing. A heterozygous G deletion (c.857delG) in exon 7 causing a frame shift in PAX6 was identified in all affected family members. Genotype-phenotype correlation analysis revealed congenital cataract and all affected family members showed a similar spectrum of aniridia with no phenotypic variability but with differences in severity that were age-dependent. In summary, by using a PCR-HRM approach, this study is the first to report a PAX6 mutation in a Malaysian family. This mutation is the cause of the aniridia spectra observed in this family and of congenital cataract.
Twelve introgressed oil palm (Elaeis guineensis) progenies of Nigerian dura x Deli dura were evaluated for bunch yield, yield attributes, bunch quality components and vegetative characters at the Malaysian Palm Oil Board Research Station, in Keratong, Pahang, Malaysia. Analysis of variance revealed significant to highly significant genotypic differences, indicating sufficient genetic variability among the progenies for bunch yield and its attributes, vegetative characters and bunch quality components, except fruit to bunch ratio. Fresh fruit bunch yield ranged from 167 kg·palm(-1)·year(-1) in PK1330 to 212 kg·palm(-1)·year(-1) in PK1351, with a mean yield of 192 kg·palm(-1)·year(-1). Among the progeny, PK1313 had the highest oil to bunch ratio (19.36%), due to its high mesocarp to fruit ratio, fruit to bunch ratio and low shell to fruit ratio. Among the progenies, PK1313 produced the highest oil yield of 31.4 kg·palm(-1)·year(-1), due to a high mesocarp to fruit ratio (61.2%) and a low shell to fruit ratio (30.7%), coupled with high fruit to bunch ratio (65.6%). PK1330 was found promising for selection, as it had desirable vegetative characters, including smaller petiole cross section (27.15 cm2), short rachis length (4.83 m), short palm height (1.85 m), and the lowest leaf number (164.6), as these vegetative characters are prerequisites for selecting palms for high density planting and high yield per hectare. The genetic variability among the progenies was found to be high, indicating ample scope for further breeding, followed by selection.
Oil palm tissues are rich in polyphenols, polysaccharides and secondary metabolites; these can co-precipitate with RNA, causing problems for downstream applications. We compared two different methods (one conventional and a kit-based method - Easy-Blue(TM) Total RNA Extraction Kit) to isolate total RNA from leaves, roots and shoot apical meristems of tissue culture derived truncated leaf syndrome somaclonal oil palm seedlings. The quality and quantity of total RNA were compared through spectrophotometry and formaldehyde gel electrophoresis. The specificity and applicability of the protocols were evaluated for downstream applications, including cDNA synthesis and RT-PCR analysis. We found that the conventional method gave higher yields of RNA but took longer, and it was contaminated with genomic DNA. This method required extra genomic DNA removal steps that further reduced the RNA yield. The kit-based method, on the other hand, produced good yields as well as well as good quality RNA, within a very short period of time from a small amount of starting material. Moreover, the RNA from the kit-based method was more suitable for synthesizing cDNA and RT-PCR amplification than the conventional method. Therefore, we conclude that the Easy-BlueTM Total RNA Extraction Kit method is suitable and superior for isolation of total RNA from oil palm leaf, root and shoot apical meristem.
The sympathetic nervous system plays a major role in blood pressure regulation. Beta 2 (β2) adrenoceptor gene polymorphisms have been associated with hypertension in different populations with conflicting results. We examined the association of three common polymorphisms, Arg16Gly, Gln27Glu, and Thr164Ile, of the β2 adrenoceptor gene in Malaysian hypertensive subjects. A total of 160 hypertensive and control subjects were recruited. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and anthropometric measurements were obtained from each subject. Biochemical analyses of lipid profiles were conducted with an autoanalyzer. DNA samples were extracted from blood and buccal cells. Genotyping was accomplished with polymerase chain reaction-restriction fragment length polymorphism. SBP, DBP, body mass index, and biochemical factors all differed significantly between case and control subjects (P < 0.05). The genotype frequencies of Arg16Arg, Arg16Gly, and Gly16Gly were 22.5, 70, and 7.5% among cases and 33.1, 63.1, and 3.8% among controls, respectively. The genotype frequencies of Gln27Gln, Gln27Glu, and Glu27Glu among cases were 41.1, 50, and 1.9% compared to 77.5, 20.6, and 1.9% among controls, respectively. In this study, the Gln27Glu polymorphism was significantly associated with Malaysian hypertensive subjects (P < 0.05). Therefore, the Gln27Glu polymorphism of the β2 adrenoceptor could be a risk factor associated with hypertension among Malaysians.
A phage display library of single chain variable fragment (scFv) against MCF-7 breast cancer cells was constructed from C3A8 hybridoma cells. RNA from the C3A8 was isolated, cDNA was constructed, and variable heavy and light immunoglobulin chain gene region were amplified using PCR. The variable heavy and light chain gene regions were combined with flexible linker, linked to a pCANTAB 5E phagemid vector and electrophoresed into supE strain of Escherichia coli TG1 cells. Forty-eight clones demonstrated positive binding activity to MCF-7 breast cancer cell membrane fragments and the strongest of 48 clones was selected for analysis. The anti-MCF-7 library evaluated by SfiI and NotI digests demonstrated that anti-MCF-7 scFv antibodies possess individual patterns that should be able to recognize distinct human breast cancer cells. The C3A8 scFv, with an apparent molecular weight of 32 kDa, showed high homology (99%) with single chain antibody against rice stripe virus protein P20. In summary, the anti MCF-7 scFv antibody can be used for pretargeting breast cancer for clinical diagnosis of patients; it also has potential for therapeutic applications.
Carbamazepine (CBZ) is used as the first line of treatment of complex partial seizures (CPS) in Malaysia. While this drug is known to be effective for the treatment of CPS, more than 30% of patients remain drug resistant to CBZ mono-therapy. We examined a possible relationship between patients' response to CBZ mono-therapy and the G2677T SNP of the ABCB1 gene. Three hundred and fourteen patients with CPS were recruited from the Neurology Department of the Kuala Lumpur Hospital, of whom 152 were responders and the other 162 were non-responders to CBZ mono-therapy. DNA was extracted from blood samples and real-time PCR was performed to detect the G2677T SNP of the ABCB1 gene. Results were described as genotype frequencies and compared by logistic regression analysis. Among the 152 responders, 74% had the GG genotype. However, among the 162 non-responders, 26.5% had the GT genotype and 39% had the TT genotype. There was a significant difference in genotype frequency (TT vs GG; odds ratio 4.70; 95% confidence interval, 2.70-8.20) between responders and non-responders. The presence of the T allele of the G2677T SNP appears to be a useful screening marker to determine if a patient is going to be resistant to CBZ as a single drug therapy in the treatment of CPS.