Anomalies in DNA replication, repair and recombination in ataxia-telangiectasia (A-T) point to a defect in structure or function of chromatin. In this study we have compared DNA-protein binding in nuclear extracts from control and A-T cells using two assay systems, filter-binding and DNA-accessibility. Interestingly, the extent of DNA protein binding over a range of protein concentration was significantly lower in A-T extracts. In addition the accessibility of the restriction enzyme Eco R1 to protein-bound plasmid was greater when A-T extracts were used. This is in keeping with the reduced binding observed in the filter-binding assay.
Termitomyces are delicious edible mushrooms found in Africa and South-East Asia including Malaysia. These mushrooms were found to grow symbiotically with termites around termite nests. Numerous efforts have been made worldwide to develop a cultivation method for these mushrooms. Unfortunately, none of those attempts were successful. The main obstacles encountered were the difficulty to identify and isolate pure termitomyces culture. The problem became prevalent as the culture gets contaminated by other fungi. Termitomyces can easily be identified by its mushroom fruiting body eventually but certainly not at the mycelium and hyphea stages. In this study a simple PCR-based genetic marker detection method for confirmation of termitomyces at any culture stage was developed. Using this method, four distinctive PCR assays
were developed using specific PCR primers designed based on the DNA sequence of the termitomyces mushroom. The PCR results showed that the PCR assays using intact termitomyces
DNA as template was not suitable for this purpose. However, PCR using BamHI and EcoRI predigested termitomyces DNA as template showed identical polymorphism pattern for both
termitomyces mushroom DNA and termitomyces culture DNA. Thus, the method reported here can be used for the identific.
In the search for universal vaccine candidates for the prevention of avian influenza, the non-structural (NS)-1 protein of avian influenza virus (AIV) H5N1 has shown promising potential for its ability to effectively stimulate the host immunity. This study was aimed to produce a bacterial expression plasmid using pRSET B vector to harbour the NS1 gene of AIV H5N1 (A/Chicken/Malaysia/5858/2004 (H5N1)) for protein expression in Escherichia coli (E. coli). The NS1 gene (687 bp) was initially amplified by polymerase chain reaction (PCR) and then cloned into a pGEM-T Easy TA vector. The NS1 gene was released from pGEM-T-NS1 using EcoRI and XhoI restriction enzymes (RE). The pRSET B vector was also linearized using the same RE. The digested NS1 gene and linearized pRSET B were ligated using T4 DNA ligase to form the expression plasmid, pRSET B-NS1. The NS1 gene sequence in pRSET B-NS1 was confirmed by DNA sequencing. To prepare recombinant bacterial cells for protein expression in the future, pRSET B-NS1 was transformed into E. coli strain BL21 (DE3) by heat-shock. Colonies bearing the recombinant plasmid were screened using PCR. The DNA sequencing analysis revealed that the NS1 gene sequence was 97% homologous to that of AIV H5N1 A/Chicken/Malaysia/5858/2004 (H5N1). These results indicated that the NS1 gene of influenza A/Chicken/Malaysia/5858/2004 (H5N1) was successfully amplified and cloned into a pRSET B vector. Bacterial colonies carrying pRSET B-NS1 can be used for the synthesis of NS1-based influenza vaccine in the future and thereby aid in the prevention of avian influenza.
The foxtail palm (Wodyetia bifurcata), an Australian native species, is an adaptable and fast-growing landscape tree. The foxtail palm is most commonly used in landscaping in Malaysia. Coconut yellow decline (CYD) is the major disease of coconut associated with 16SrXIV phytoplasma group in Malaysia (1). Symptoms consistent with CYD, such as severe chlorosis, stunting, general decline, and death were observed in foxtail palms from the state of Selangor in Malaysia, indicating putative phytoplasma infection. Symptomatic trees loses their green and vivid appearance as a decorative and landscape ornament. To determine the presence of phytoplasma, samples were collected from the fronds of 12 symptomatic and four asymptomatic palms in September 2012, and total DNA was extracted using the CTAB method (3). Phytoplasma DNA was detected in eight symptomatic palms using nested PCR with universal phytoplasma 16S rDNA primer pairs, P1/P7 followed by R16F2n/R16R2 (2). Amplicons (1.2 kb in length) were generated from symptomatic foxtail palms but not from symptomless plants. Phytoplasma 16S rDNAs were cloned using a TOPO TA cloning kit (Invitrogen). Several white colonies from rDNA PCR products amplified from one sample with R16F2n/R16R2 were sequenced. Phytoplasma 16S rDNA gene sequences from single symptomatic foxtail palms showed 99% homology with a phytoplasma that causes Bermuda grass white leaf (AF248961) and coconut yellow decline (EU636906), which are both members of the 16SrXIV 'Candidatus Phytoplasma cynodontis' group. The sequences also showed 99% sequence identity with the onion yellows phytoplasma, OY-M strain, (NR074811), from the 'Candidatus Phytoplasma asteris' 16SrI-B subgroup. Sequences were deposited in the NCBI GenBank database (Accession Nos. KC751560 and KC751561). Restriction fragment length polymorphism (RFLP) analysis was done on nested PCR products produced with the primer pair R16F2n/R16R2. Amplified products were digested separately with AluI, HhaI, RsaI, and EcoRI restriction enzymes based on manufacturer's specifications. RFLP analysis of 16S rRNA gene sequences from symptomatic plants revealed two distinct profiles belonging to groups 16SrXIV and 16SrI with majority of the 16SrXIV group. RFLP results independently corroborated the findings from DNA sequencing. Additional virtual patterns were obtained by iPhyclassifier software (4). Actual and virtual patterns yielded identical profiles, similar to the reference patterns for the 16SrXIV-A and 16SrI-B subgroups. Both the sequence and RFLP results indicated that symptoms in infected foxtail palms were associated with two distinct phytoplasma species in Malaysia. These phytoplasmas, which are members of two different taxonomic groups, were found in symptomatic palms. Our results revealed that popular evergreen foxtail palms are susceptible to and severely affected by phytoplasma. To our knowledge, this is the first report of a mixed infection of a single host, Wodyetia bifurcata, by two different phytoplasma species, Candidatus Phytoplasma cynodontis and Candidatus Phytoplasma asteris, in Malaysia. References: (1) N. Nejat et al. Plant Pathol. 58:1152, 2009. (2) N. Nejat et al. Plant Pathol. J. 9:101, 2010. (3) Y. P. Zhang et al. J. Virol. Meth. 71:45, 1998. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.
The DNA of three biological variants, G1, Ic and G2, which originated from the same greenhouse isolate of rice tungro bacilliform virus (RTBV) at the International Rice Research Institute (IRRI), was cloned and sequenced. Comparison of the sequences revealed small differences in genome sizes. The variants were between 95 and 99% identical at the nucleotide and amino acid levels. Alignment of the three genome sequences with those of three published RTBV sequences (Phi-1, Phi-2 and Phi-3) revealed numerous nucleotide substitutions and some insertions and deletions. The published RTBV sequences originated from the same greenhouse isolate at IRRI 20, 11 and 9 years ago. All open reading frames (ORFs) and known functional domains were conserved across the six variants. The cysteine-rich region of ORF3 showed the greatest variation. When the six DNA sequences from IRRI were compared with that of an isolate from Malaysia (Serdang), similar changes were observed in the cysteine-rich region in addition to other nucleotide substitutions and deletions across the genome. The aligned nucleotide sequences of the IRRI variants and Serdang were used to analyse phylogenetic relationships by the bootstrapped parsimony, distance and maximum-likelihood methods. The isolates clustered in three groups: Serdang alone; Ic and G1; and Phi-1, Phi-2, Phi-3 and G2. The distribution of phylogenetically informative residues in the IRRI sequences shared with the Serdang sequence and the differing tree topologies for segments of the genome suggested that recombination, as well as substitutions and insertions or deletions, has played a role in the evolution of RTBV variants. The significance and implications of these evolutionary forces are discussed in comparison with badnaviruses and caulimoviruses.