Characterization of the shrimp eyestalk cDNA encoding a novel fushi tarazu-factor 1 (FTZ-F1)

To study the role of ecdysone and the ecdysone inducible gene in the regula tion of molting and development in crustaceans, we have cloned a cDNA encod ing an orphan nuclear receptor family member from the eyestalk of the shrim p Metapenaeus ensis. The size of the cDNA is 4.3 kb with the longest open r eading frame (ORF) encoding a protein of 545 amino acid residues, The deduc ed amino acid sequence of the shrimp cDNA consists of regions that are char acteristic of those of the nuclear hormone receptors, It shows a high degre e of amino acid sequence identity in the DNA binding domain, ligand binding domain and the FTZ box as compared to those of invertebrates and vertebrat es. Unlike the insects Drosophila melanogaster and Bombyx mori, an AF2 tran sactivation domain was present in the shrimp FTZ-F1, Northern blot analysis using total RNA indicated that the FTZ-F1 mRNA could also be detected in t he mature ovary. Northern blot analysis and RT-PCR analysis showed that the shrimp FTZ-F1 transcripts could be detected in the ovary, newly hatched na uplius, testis, eyestalk and epidermis of the adult shrimp. Although the cD NA clone was isolated from the eyestalk library, the shrimp FTZ-F1 appeared to express most abundantly in the mature oocytes, The presence of abundant FTZ-F1 specific maternal message in the late vitellogenic ovary and early nauplius indicates that it may be important for the early embryonic and lar val development of the shrimp. Interestingly, shrimp FTZ-F1 can also be fou nd in testis of the male shrimp. The presence of FTZ-F1 in other tissues su ch as epidermis suggests that it may also be involved in other physiologica l processes such as molting. (C) 1999 Federation of European Biochemical So cieties.