Meeting Abstract
The grapsid crab M. messor exhibits definite season dependent patterns of programming of molting and reproduction while Aug-Dec is devoted for breeding activity, Jan-May season is devoted for both molting and breeding. Jun-Jul however is characterized by molt reproductive repose; ovaries of the entire population would be inactive during Jun- Jul season, with no signs of yolk deposition and the entire population would remain in intermolt during this season. The ultrastructural and immunohistochemical (IHC) studies reveal that YO activity in M. messor is at its peak in premolt animals during Jan-May season. These results are being compared with the results of the ecdysteroid titer in relation to various seasons of the year and also pertaining to growth and reproduction. During the breeding season on the other hand the activity was much less than what was registered in premolt crabs. The RIA of the ecdysteroid level revealed the existence of a correlation between ecdysteroid levels and the YO activity. The ecdysteroid nature of the secretion was ascertained through IHC studies. We also report the sequence information on the DNA Binding Domain (DBD), linker (D domain) and Ligand Binding Domain (LBD) of M. messor ecdysteroid receptor (MmEcR) gene. We have also measured MmEcR mRNA transcript levels in the ovary and the hepatopancreas throughout the annual cycle, with special reference to seasons of molt and reproduction. MmEcR expression in both the tissues is found to be at its peak (<0.05) in late premolt crabs (Jan/May), implicating a possible ecdysteroid role in reproduction in M. messor.
