Mantle tissue from the black-lip pearl oyster, Pinctada margaritifera, was cultured in vitro using sterilized seawater supplemented with 0.1% yeast extract as the culture medium. Granular and agranular epithelial cells, hyalinocytes, and fibroblast-like cells were observed in the initial stages of culture. Epithelial cells later formed pseudopodial cell networks containing clusters of granulated cells, which upon maturation released their colored granules. These granules induced formation of nacre crystal deposits on the bottom of the culture plate. Cultures comprised of only granulated epithelial cells were established through periodic sub-culturing of mantle cells and maintained for over 18 mo in a viable condition. Reverse transcriptase PCR of cultured cells demonstrated gene expression of the shell matrix protein, nacrein. To further evaluate the functional ability of cultured granulated epithelial cells, nuclear shell beads were incubated in culture medium containing these cells to induce nacre formation on the beads. Observation of the bead surface under a stereomicroscope at periodic intervals showed the gradual formation of blackish yellow colored nacre deposits. Examination of the bead surface by scanning electron microscopy and energy dispersive X-ray analysis at periodic intervals revealed a distinct brick and mortar formation characteristic of nacre, comprised of aragonite platelets and matrix proteins. Calcium, carbon, and oxygen were the major elements in all stages examined. Our study shows that mantle epithelial cells in culture retain the ability to secrete nacre and can therefore form the basis for future studies on the biomineralization process and its application in development of sustainable pearl culture.

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The aim of the present study was to establish a suitable culture system for tissue explants from the mantle of the green mussel, Perna viridis. The experiments were conducted using healthy, live green mussels in the size range of 75 to 110 g collected from Pulicat Lake, Tamil Nadu. Three different culture media namely M199, Leibovitz L-15 and sterile seawater were used to assess the most suitable medium for growth, proliferation and viability of mantle epithelial cells. The effect of the addition of two supplements viz., 10% foetal calf serum (FCS) and 0.1% yeast extract to the culture media was also evaluated. After carefully isolating the pallial layer from the mantle tissue, 1-2 mm2 size explants were successfully cultured in 12-well plates at 25°C for up to 14 days. Cultures were monitored under light and phase contrast objectives in an inverted microscope. Cell counts were made and cell size was measured for each treatment. Cells were observed to migrate from the periphery of the explant within 24 h after initiation of cultures. The liberated cells were mostly round and were either granulocytes or hyalinocytes. Fibroblast-like cells were also observed. Our results showed that proliferation of epithelial cells from mantle tissue was maximum in seawater medium (7.4x104 cells ml-1), followed by L-15 medium (2.55x104 cells ml-1). Average cell size in seawater medium was 10.72 μm and that in L-15 and M199 media was 8.56 and 6.39 μm, respectively. Adherent cells were also more prominent and higher in number in seawater medium. Supplementation of culture media with 10% FCS and 0.1% yeast extract improved both cell proliferation and cell size in all the three culture media. Four concentrations of 0.1% yeast extract (@ 50 μl, 75 μl, 100 μl, 150 μl ml-1 medium) were tested in the present study and best results were obtained with 100 μl ml-1, with respect to both cell counts and size.

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Erratic monsoon and extreme climatic events cause considerable damage to life and property of the fishers in the country. Cuddalore District has been the worst affected of all districts in Tamil Nadu, in the recent past with the tsunami in 2004, cyclone Thane in 2011 and cyclone Neelam in 2012 creating a detrimental impact on coastal communities and their activities, particularly fishing. This in turn has affected their livelihood to a great extent. This coastal zone is largely low-lying with gentle slope, thus making it highly vulnerable to climate related changes. The vulnerability of this region to climate change and its devastating effects necessitates identifying vulnerability indices to assist in developing proactive policies by local government bodies in better disaster management. The vulnerability index of ten coastal villages of Cuddalore District was computed using Parameter, Attribute, Resilient indicator and Score (PARS) method. The study showed that the Cuddalore coast is highly vulnerable to climate change and related sea level rise. The villages of Pettodai, Reddiarpettai and Sothikuppam of Cuddalore District were identified as most vulnerable. The outcome of this study will be of use in the protection of coastal livelihoods and planning better adaptation policies and mitigation plans.