AREA OF RESEARCH SPECIALIZATIONS 

(Listed in alphabetical order)

Dr. P. Gunasekaran:

His team has been working on Zymomonas mobilis, an unique bacterium producing ethanol. He confirmed that the lower efficiency of ethanol production from sucrose by this organism is due to levan and sorbitol formation. He has isolated novel mutants (levan non-forming) with an improved efficiency of ethanol production and he optimized conditions for ethanol production without levan and sorbitol formation. He has identified three different sucrases in Z. mobilis and their role in sucrose fermentation. (a) an intracellular sucrase (SacA) - found to have no significant role in sucrose fermentation (b) an extracellular levansucrase (SacB) - found to be responsible for levan production and decrease in fermentation efficiency and (c) an extracellular sucrase (SacC) - found as key enzyme in sucrose hydrolysis and in improved fermentation efficiency. He also identified, cloned, sequenced and characterized their corresponding sucrase genes and found sacB and sacC encoding the extracellular enzymes were located close to each other, forming a gene cluster and related to each other but without leader peptide sequence while sacA coding for an intracellular enzyme is unrelated

Dr. M. H. Munavar & Dr. R. Jayaraman

Our laboratory has been studying control of transcription in E. coli for a very long time. Initially by way of identifying a temperature sensitive transcription defective mutant (fitA 76) and subsequently by way of identifying two of its suppressors, (fitA24 and fitB). Two genes (fitA and fitB) whose products control transcription have been identified. Genetic, physiological and biochemical studies indicated that these two gene products (FitA and FitB) interact with each other as well as with RNA polymerase, probably b-subunit, and regulate expression of a few classes of genes, among them could be the genes coding for ribosomal proteins. Molecular cloning and characterization of fitA gene together with available results indicate that FitA and FitB products could be same as a and b-subunits of enzyme phenylananyl tRNA synthetase (PheRS), an enzyme primarily involved in translation. Thus our work on transcription control led to the elucidation of the new second function associated with the enzyme PheRS. Further it has been shown that the originally identified fitA 76 mutant itself harbours two lesions. a G₂₉₃       A₂₉₃ transition in pheS , locus (pheS5) arid another mutation, named fit95, possibly located in the pheT  locus. It is well known that pheS5 mutation by itself confers a primary defect in translation at 42°C and our work indicates that both pheS5 and fit95 are needed together to elicit the phenotype characteristic of fitA 76 mutant.  Recently, another suppressor named (fitC4) capable of suppressing the Ts phenpotype of pheS5 mutant but not that of fitA 76 mutant has been identified. We are currently interested in further characterizing both fit95 and fitC4 mutations. In future, we would like to identify the genes defined by these mutations and also identify the actual lesions in these mutants. Also, we would like to identify as many as possible genes whose transcription is dependent on Fit factors. Using such Fit dependent genes we would like to develop an assay system to monitor the Fit function in vitro. 

We have been working on adaptive mutagenesis for the past 7-8 years. Initial work revealed that the product of mutS and mulL genes negatively regulate the two pathways of adaptive mutagenesis. Recently, another mutation designated ppm (for post-plating mutagenesis) mapping close to rpsL locus has been identified. It has been shown that there is a correlation between leakiness of genetic markers and susceptibility to post- plating mutagenesis and it is believed that ppm mutation, increases the intrinsic leakiness of genetic markers perhaps due to increased translational errors. Recently a mutagenic ochre suppressor mutation has been identified. It has been shown that the mutagenic effect of this mutation is dependent on the ppm mutation. In future, we would like to further characterize ppm and the mutagenic ochre suppressor mutations and also would like to identify the genes and lesions defined by both ppm and mutagenic ochre suppressor mutations.

Dr. G. Kulandaivelu

Identified the molecular targets of UV-B radiation and the ameliorative properties of other stresses in this.

Developed UV-B radiation resistant strains of Cyanococcus and Scenedesmus through adaptive mutagenesis

Characterized the photsynthetic apparatus of UV-B mutants with reference to DI and 33kDa OEC protein

Dr. S. Mathavan:

Standardized the methods for gene transfer into the eggs of fish and silkworm. Demonstrated heritable genomic integration of injected gene in cat fish. Established sperm mediated gene transfer techniques for the first time in silkworm. We have also shown the extra chromosomal persistence and transmission of injected genes in the silkworm. Cloned and sequenced mariner transposable element for silkworm and looking for the possibilities of using it as germline transformation vector.

Baculovirus expression system

Established facility for gene expression using Bombyx mori baculovirus expression vectors in silkworm larvae and BmN cells. Successfully expressed human parathyroid hormone (hPTH) in the silkworm larvae. Demonstrated the biological activity of recombinant human parathyroid hormone produced in silkworm. There is a scope for commercialization of the project.

Baculovirus and Biocontrol:

Working on the production of recombinant baculovirus for the control of the insect pest Helicoverpa armegira and Amsacta albistriga. Completely mapped the 120 Kb nuclear polyhedrosis viral genome of the H. armigera and A. albistriga. At present making effort to construct transfer vector for the production of recombinant virus,

Dr. K. Manoharan

A cell plating methodology leading to the formation of highly embryogenic microcalli and subsequent development of plantlets was worked out for the indica rice cultivar IR 20. Also, an efficient protocol for DNA delivery by microprojectile bombardment into cells and the transient expression of b-glucuronidase gene in the plated cells was worked out.

Membrane lipid composition of total callus and its plasma membrane enriched fraction of rice cultures grown on media supplemented with various growth factors, such as choline (substrate for the biosynthesis of phosphatidylcholine), putrescine (a polyamine) and pectin (a soluble cell wall hydrolysate-oligosaccharide), was worked out. Choline was found to be growth stimulatory and putrescine/pectin were growth inhibitory in these cultures.

Dr. RM. Pitchappan

Human Leprosy Genome Scan has been completed in the collaborator laboratory at University of Oxford: 236 affected sib-pair families from Kumbakonam and Sakthinagar has been studied. Of the five different regions mapped with appreciable lod score, one of them -seems to have the highest lod score: This locus may be the prime one for leprosy susceptibility. Human Genome Scan for a S. Indian Leprosy patients has been completed in the collaborator laboratory, at University of Oxford, UK. The regions contributing to the disease development have thus been mapped and the paper is published in Nature Genetics. Further work on positional analysis is underway. HLA association of pulmonary tuberculosis in south India has again been reiterated employing molecular HLA typing methodologies. This supports the hypothesis ‘Not all the infected develop the disease’

Dr. C. Rajamanickam

Of the many questions that are raised in understanding the phenomenon of hypertrophic cardiac enlargement and subsequent myocardial failure the question of identification of various molecular biochemical factors which play an indispensable role in eliciting the hypertrophic growth response in the myocardium is very important and pertinent to the studies in this laboratory. The main objective of Prof. C.Rajamanickam's laboratory is to unravel the molecular mechanisms of heart diseases and introduce the molecular concepts in diagnostic and therapeutic approaches.

Following are the highlights of the investigations carried out so far in this laboratory:

Studies on the regulation of myofibrillar protein gene expression showed that both transcriptional and post-transcriptional regulations are operative in Beta MHC gene expression during the development of cardiac hypertrophy.

Further, these studies have lead to the identification and characterization of a transcription factor of molecular weight 45 kDa that specifically binds to the upstream regulatory sequences of Beta MHC gene and activates its expression during cardiac hypertrophy. These studies have brought out the essential role of this E-box binding, muscle specific and stage specific transcription factor in the process of cardiac hypertrophy.

Studies from this laboratory have also shown the presence of a novel cardiac hypertrophy specific serum protein of molecular weight 182 kDa in the sera of animals subjected to develop cardiac hypertrophy. It is suggested that this protein could be a specific signaling protein that signals hypertrophic growth of the myocardium under stress conditions. Evidences such as induction of proto- oncogenes and protein kinase C, induction of MLC2 and Beta MHC genes and scanning electron microscopic analysis of cardio myocytes showing expanded myofibers in the hearts of animals treated with this specific protein have established a signaling role for this protein through a signal transduction mechanism operating in the development of cardiac hypertrophy.

Studies on this hypertrophy specific serum protein in human patients with hypertrophic hearts and in experimentally induced myocarditis in animals have raised the possibility of employing this protein in molecular diagnostic as well as in therapeutic approaches in cardiac ailments.

Dr. G. S. Selvam

Molecular cloning and expression of oxalyl CoA decarboxylase and formyl CoA transferase genes from Acinetobacter and Alcaligenes species. The ability to enzymatically degrade oxalate to less noxious substances, formate and CO₂, could benefit a great number of individuals in the biomedical field. The objectives of our work is cloning and expression of oxalate degrading enzyme genes of Acinetobacter and Alcaligenes sp. The recombinant enzyme will be employed for treating calcium oxalate stone disease. Biochemical and molecular studies of cadmium resistance and metal biosorption in bacterial species isolated from Cochin environment. Heavy metal affects every level of organisms from society to organ and sub-cellular level. The effect of heavy metal cadmium on the fresh water prawn Macrobrachium idella was studied using two different concentrations of cadmium ions at different exposure periods. An attempt was made to isolate and purify the metallothionin protein (MT proteins) from cytosolic fractions of liver tissues and the bioadsorption of the metal (Cadmium) by selected bacterial strains in order to find out efficiency in removing the metal. Isolation and characterization of growth hormone (GH) coding gene in Penaeus sp. Penaeid prawns, especially Penaeus indicus, P. monodon and P. semisulcalus is export commodity which fetch enormous foreign exchange. In aquaculture practice shortening life span, enhancing weight etc., could be achieved if the levels of growth hormones in individuals are altered through gene manipulation.

Dr. S. Shanmugasundaram & Dr. S. Suguna

Our group has isolated, cloned and expressed protease, lipase and amylase coding genes from bacterial strains. We have also identified novel restriction nucelases from the cyanobacterial periplasm. A rapid and simple method for the purification of these enzymes has been devised. Genetically tagged strains of cyanobacteria, were constructed and released in rice fields. Cyanobacterial DNA modifying enzymes have been identified.

Dr. G. Shanmugam

Demonstration of alterations in the ras oncogene and in the p53 tumor suppressor: gene of oral cancer. Ras gene mutations were relatively high and p53 mutations were low in oral cancers of Indians compared to those of the developing countries.  Prof. Shanrnugam and his group have discovered novel anticancer properties for a plant-derived compound called cleistanthin A.   This compound was found to be selectively toxic to tumor cells and does not affect the body weight or lympocyte count of treated animals. 

Dr. K. Chandaraj

The broad area of expertise is Genetic Engineering and Biochemistry towards application of bio-systems to industrial process.  A xylanase enzyme from newly isolated alkali-tolerant Asprgillus fischeri was purified and chareacterized. This enzyme to remove residual xylan from brown pulp during bio-bleaching was assessed. The possibility of regeneration of xylanase after biobleaching was assessed for recycling of xylanase in industries.

The biochemistry and molecular biology of levansucrase from Zymomonas mobilis a well known ethanologen was investigated. Levansucrase minimizes the yield of ethanol by converting fructose to levan a polymer of fructose. The levan-forming activity of levansucrase was eliminated by chemical modification of levansucrase using thiol-group specific reagents.

Cloned, expressed and characterized two bacterial pyruvate decarboxylase from Acetobacter pasteurianus and Zymobater palmae for construction of novel ethanol production operons. Metabolic engineering to improve ethanol yield requires the diversion of pyruvate to ethanol. PDC catalyses the oxidative decarboxylation of pyruvate to acetaldehyde which is subsequently converted to alcohol by ADH during ethanol fermentation. Currently, cloned and sequenced two pdc genes from gram –ve bacteria Acetobacer pasteurianus and Zymobacter palmae (Submitted to GENE DATABASE). Also the PDCs produced from the recombinant E. coli carrying these pdc genes were purified and characterized.