Development of bacterial biosensors that sense toxic levels of Cd, Zn, Pb and Hg ions and express GFP at levels corresponding to the concentration of the pollutant.

A transgenic zebra fish that expresses green fluorescent protein on exposure to genotoxic stressors was developed as a part of overseas training in transgenesis at University of Minnesota, USA, funded by NATP in 2003. Tests were completed in F 0 fishes and work is to be continued for obtaining true transgenics.

Four novel genes associated with osmoregulation in P. monodon have been identified under an AP Cess funded project.

Molecular genetics studies were carried out on various fin and shellfish species using allozymes, MASA, RAPD and microsatellites. Salient findings are as follows:

A DNA profile (MASA, microsatellite associated sequence amplification) based method to distinguish between C. batrachus, C. gariepinus and H. fossilis. Studies on P. monodon populations from various geographical locations using allozyme, RAPD and microsatellite, morphometric markers showed high genetic variation within the species but insignificant variation between populations. Significant variation is present in economic characters, which can be utilised, for genetic selection and up-gradation of the animal. There is significant difference in the morphometric characters of wild and cultured animals implying the significance of management practices. The present study indicates that the abdominal segment circumference (girth) contributes more to the total variation than the abdominal length and it should find a place in selection criterions. Based on the present set of morphometric characters, the sample size from west coast and the statistical tests it can not be possible to detect conclusively the difference between east and west coast animals. Studies on selected M. rosenbergii populations using allozyme and RAPD revealed genetic variation within and between stocks. The phylogenetic relationship between stocks was analyzed.

Sub lethal concentrations of cadmium, zinc and lead caused genetic damage in Lates calcalifer and Chanos chanos in terms of chromosomal aberration. Cadmium caused maximum damage to the genetic constituent. Micronuclei Test was observed to be the fastest test to find out the heavy metal pollution status of the aquatic environment

Clarias batrachus milt was evaluated and its chemical and biochemical composition was analyzed. The milt was further extended in the artificially prepared extender with cryoprotectant. The milt was then cryopreserved under liquid nitrogen using horizontal freezing technique. SEM and TEM studies were conducted. Cryopreservation was successful for 2 months and fertility trials yielded 15-20% fertilization.

Inbreeding in carp stocks used in selected State hatcheries from Maharashtra, Gujarat and Karnataka was estimated and the stocks were found to be genetically closed. An un-intentional negative selection had crept in. A high probability exists for introgression because of the lacuna in reproductive management. Improvement measures were suggested to the hatcheries.

The optimal sperm: egg ratio (12000:1) was determined for rohu. This ratio may be adopted for having uniform dilution ratio in cryopreservation of rohu milt.

Intraspecific variations among the hatchery bred rohu population of three states, Maharashtra, Gujarat and Karnataka were estimated. The hatchery stocks vary with respect to truss measurements and as such need to be treated as separate stocks. There is need to develop separate broodstock management practices for these stocks so as to maintain the stock identity.