Molecular cloning of a female-specific cDNA with unique repeat sequences from the fat body of the adult locust, Locusta migratoria

A cDNA clone encoding a 25-kDa protein (25K) was isolated from a cDNA libra ry made from RNA isolated from the adult fat body and ovaries of the locust , Locusta migratoria. The longest open reading frame of this cDNA clone enc odes a 225-amino acid polypeptide, the N-terminal end of which was similar to the 21-kDa and 19-kDa juvenile hormone induced proteins identified in th e locust hemolymph, but the C-terminal end was different. The C-terminal en d of the 25K cDNA contained seven unique repeat elements of 10 amino acids each, most of which are polar residues. Expression of the 25K mRNA was tiss ue-, development- and sex-specific. A 1.2-kb mRNA was detected using the 25 K cDNA as a probe only in the fat body of adult females. The mRNA started t o appear at day 4 after the insect molted to the adult and rapidly increase d by day 6. The mRNA was absent in the ovarian follicle cells and fat body of adult males. In vitro transcription and translation of the 25K cDNA prod uced a protein that migrated around 32 kDa on sodium dodecyl sulfate polyac rylamide gels. The 25K cDNA was expressed in a baculovirus expression syste m and the protein produced also migrated around 32 kDa, (C) 2000 Elsevier S cience Ltd. All rights reserved.