PARENT SESSION

(T356) IDENTIFICATION OF AN OOCYTE-SPECIFIC OXYSTEROL BINDING PROTEIN IN RAINBOW TROUT.

Ramachandra, Raghuveer¹, Yao, Jianbo¹, ¹ West Virginia University, Morgantown, WV

ABSTRACT- Normal reproductive development in rainbow trout as in any other organisms requires a coordinated expression of many gene products. Genes specifically expressed in oocytes are important for the development of oocytes and early embryos. By analyzing expressed sequence tags (ESTs) from a rainbow trout oocyte cDNA library, we identified a novel EST sequence that does not show homology to any sequences in the GenBank database. Analysis of tissue distribution of this transcript by reverse transcription polymerase chain reaction revealed that this gene was only expressed in unfertilized oocytes but not in 10 other tissues examined. The EST clone was retrieved and subjected to DNA sequence determination. The complete cDNA sequence of the clone was 3164 bp in length. Further sequence analysis revealed that the cDNA has an open reading frame coding for a protein of 492 amino acids and the predicted amino acid sequence has a conserved oxysterol binding protein domain at the C terminus that is characteristic of oxysterol binding proteins (OSBPs). OSBPs are known to play a significant role in the regulation of lipid metabolism and cholesterol homeostasis in higher vertebrates. They are also shown to be involved in apoptosis and cell differentiation. To date, 12 members of this protein family have been identified in humans and mice and many of the members are expressed in a tissue-specific manner. Unlike any other members in the OSBP family, this newly identified member is oocyte-specific and may play an important role in the synthesis, transportation and metabolism of lipids during oogenesis and embryogenesis in rainbow trout (Supported by a USDA cooperative agreement No. 58-1930-2-237).

KEY WORDS: rainbow trout, oocyte, OSBP, embryogenesis