Mohammad Ashraful Alam
 B.Sc. Fisheries (Hons) Bangladesh Agricultural University
 M.S. (Fish Biology and Genetics), Bangladesh Agricultural University
 M.Sc. (Reproductive Biology/Endocrinology), University of the Ryukyus (On-going)

Changing from one sex to another is not just a biological ingenuity; it is a way of life in some hermaphrodite fish. Honeycomb grouper, the conspicuously colorful teleost fish inhabiting coral reefs in the tropical Asia and Pacific, is a protogynous hermaphrodite (i.e., changing sex from female-to-male at a certain stage of life cycle). They born as female and commence sex change, when they grow approximately 20cm in total length, coinciding with the sexual maturity, i.e. it usually happens when they complete their first spawning cycle. This is an interesting event, but what triggers this transformation is not known yet. The sex hormones are likely factors to regulate this change, however, which hormones and when exactly they act on germ cells to change their fate are as yet unknown. Recently, our laboratory has unveiled a key factor that is essential for maintenance of female sex, i.e. estradiol-17β (E2). My plans are to unveil what triggers testicular differentiation during the onset of sex change. At the first phase of my research I have found that androgen-producing cells are located in the outer periphery and inside the ovary. These sites probably play important role in producing androgen, that eventually triggers hormonal/molecular cascades to induce male germ cell development in the ovary. In order to elucidate this process, I plan to use both recently developed sensitive biochemical and molecular biological tools.

Publications:

Alam, M.A., Komuro, H., Bhandari, R.K. , Nakamura, S., Soyano, K., and Nakamura, M., (2005). Immunohistochemical evidence identifying the site of androgen production in the ovary of the protogynous grouper, Epinephelus merra . Cell and Tissue Research (in press)

Alam, M.A., Bhandari, R.K., Kobayashi, Y., Soyano, K., and Nakamura, M. (2005). Changes in androgen-producing cell size and circulating 11-ketotestosterone levels during female-to-male sex change in Honeycomb grouper (Epinephelus merra). Submitted to the Journal of Endocrinology.

Alam, M.A., Bhandari, R.K., and Nakamura, M. (2005). Timecourses of gonadal restructuring during aromatase inhibitor-induced protogynous sex change in the honeycomb grouper (Epinephelus merra). in preparation.

Alam, M.A., Bhandari, R.K., and Nakamura, M. (2005). Secondary males of honeycomb grouper reverse sex with hormonal manipulation. in preparation.

Bhandari R.K., Alam, M.A., Higa, M., Soyano, K. and Nakamura, M. (2005). Evidence that estrogen regulates the sex change of honeycomb grouper (Epinephelus merra), a protogynous hermaphrodite fish. J. Exp. Zool. (in press)

Bhandari, R.K. , Alam, M.A., and Nakamura, M., (2005). Efficacy of aromatase inhibitor (Fadrozole) to suppress estradiol-17β production in the ovary of honeycomb grouper (Epinephelus merra). Aquaculture (in review)

Bhandari, R.K. , Alam, M.A., and Nakamura, M., (2005). Sex change in honeycomb grouper (Epinephelus merra).(review, in preparation)