About Me:
This is to bring your kind attention that I am working as a Senior Research Fellow in National Botanical Research Institute (NBRI), Lucknow, India. I am looking forward to find post doc fellowship which has keen interest in addressing fundamental questions in the area of Virology/Biochemistry/Molecular biology/Gene-expression.
My work is focused on molecular characterization of cotton leaf curl virus associated with leaf curl disease infecting cotton and their vector whitefly (Bemisia tabaci) focusing on genomic component of Begomovirus DNA-A and their satellites DNA-beta and DNA-1 (nanovirus like particle). During Ph.D., I have carried out studies on ex-pression of genes like Replicase, Coat protein and beta C1 in tobacco both sense and antisense direction. Transgenic plants showed gene silencing on the basis of RNAi (RNA interference) not their protein. Further, I have also done studies on effect of beta C1 and their promoter in tobacco. During my research, I have exposed to recent molecular biology and cell biology techniques like: PCR, primer designing, gene expression in E.coli, blotting (Southern, Northern and Western), protein purification, cloning, transformation, Enzyme assays/ kinetics and tissue culture.
I believe that with my experience and knowledge, I can work independently on any project starting from designing of experiments to carrying them up to publication and successful completion.
Project Info:
Brief summary description of Ph.D Thesis
“Molecular characterization of DNA Components associated leaf curl disease of cotton”.
During Ph.D., the major objective of the research was to focus on molecular characterization of cotton leaf curl virus genomic components (DNA-A, DNA and DNA-1). Cotton leaf curl disease (CLCuD) is a major threat to the cotton industry and has a complex etiology. It was transmissible through whitefly a begomovirus (family Geminiviridae) containing ssDNA circular genome about 2.7 to 3 kb. Despite the identification and involvement of Begomovirus in Cotton leaf curl disease, its additional satellite DNA molecules were characterized (DNAβ and DNA-1 with CLCuD, the expected causative agents).
The identification and association of Cotton leaf curl virus (CLCuV, genus begomovirus) and additional satellite DNA molecules such as DNAβ and DNA-1 was established by PCR using overlapping primers and amplicons were cloned and sequenced. The sequence data of DNA-A (2753 bp GenBank Acc. No. DQ191160), DNA β (1350 bp Acc.No.191161) and DNA-1 a nanovirus like particle (GenBank Acc. No. EF121323) were submitted to GenBank.We have also monitor the virus in its vector whiteflie.
Geminiviruses are plant viruses with circular ssDNA genomes that are replicated by the host plant DNA polymerases. We have analyzed the genetic diversity of cotton leaf curl geminivirus (CLCuV). Genetic variability, estimated as nucleotide diversities at synonymous positions in open reading frames (ORFs) for the AC1 (Rep) protein and coat protein (AV1), was very high. Evidence for recombination was found for the AC1 and CP ORFs and for the noncoding intergenic region (IR). Data indicate that the origin of replication is a major recombination point in the IR. Analyses of the IR also suggest that recombinants may be frequent in the population and that recombination may have an important role in the generation of CLCuV variability.
Geminivirus have bidirectional promoter transcribe in both orientation. Analysis of the sequence identified six conserved predicted ORFs in (DNA-A) that encodes products termed V1 and V2 (coat protein) transcribed in clockwise direction whereas, C1 (Rep), C2, C3 and C4 are transcribed anticlockwise direction.
For the characterization of DNA β a satellite molecule have a symptom modulating agent. Mapped a DNA β transcript to a highly conserved open reading frame (βC1 ORF), an A-rich region, located between ORF βC1 and the SCR, may have been responsible for the size adaptation of DNA β from a preexisting progenitor component of unknown origin.
The βC1 ORF has the capacity to encode a 13.8 kDa protein comprising 118 amino acids is symptom modulating agents. N. benthamiana was transformed with βC1 gene, both in sense and antisense direction and data shows that, in sense transgenic lines plant exhibit symptoms like effect but those expressing βC1 in antisense confers stable heritable resistance to CLCuD in tobacco used as a model system. This resistance is likely to be due to RNA silencing by the geminiviral transgenes rather than by expression of trans-dominant proteins as lack the signal expected for protein synthesis.
Based on these observations, it is suggested that βC1 may play a role in developmental regulation by interfering with miRNA biosynthesis, even though the exact mechanism is not known. It is speculated that the βC1 protein may affect the activity of the DICER-like proteins in plants. The other suggested possibilities are that βC1 protein down regulates transcription of host protein that acts as a PTGS pathway in cytoplasm, or βC1 could activate transcription of host PTGS inhibitors.
It is my fervent hope that the combination of my background in Biochemistry and scientific research, along with an intense scientific curiosity and dedication, will stand me in good stead as a postdoctoral candidate. My diverse work experience in different fields has given me flexibility and maturity to adapt new circumstances. It would, therefore be my privilege to work as a postdoctoral fellow in your lab.
(JAVED AHMAD)