Abstract:
A vasa-like gene, Mrvlg, from the ovary of the giant freshwater prawn,
Macrobrachium rosenbergii, was isolated and characterized by a reverse transcriptionpolymerase
chain reaction (RT-PCR) method. A full-length sequence was obtained by
the rapid amplification of cDNA end (RACE-PCR) method. Analysis of the
nucleotide sequence revealed that Mrvlg comprised 2,686 bps with an open reading
frame of 2,133 bps encoding 710 amino acids. The deduced amino acid sequence
contained four arginine-glycine-glycine motifs, three zinc-finger motifs and eight
conserved motifs belonging to the DEAD-box protein family. The MrVLG sequence
showed high similarity to Vasa homologue of zebrafish (73%). The Mrvlg transcripts
were specifically detected in the germ cells of the adult gonads and also detected in
early embryonic and larval stages. In situ hybridization analysis showed that Mrvlg
RNA was detected in the cytoplasm of oogonia, previtellogenic and vitellogenic
oocytes and was also detected in the nucleoplasm of mature oocytes. Similarly, the
Mrvlg transcripts were detected in the cytoplasm of spermatogonia and primary
spermatocytes and in the nuclei of secondary spermatocytes and sperm. Sequence
similarity and specific localization in the germ cells suggest that Mrvlg is the prawn
vasa homologue of the Drosophila gene and can be used as a molecular marker for
prawn germ cells