Molecular cloning and characterization of Dmc1, a gene involved in gametogenesis, from the whiteleg shrimp Litopenaeus vannamei

Abstract

In order to gain a better understanding of the developmental processes of shrimp germ cells, the molecular cloning and characterization of a meiosis-related gene, Dmc1, was carried out using the whiteleg shrimp Litopenaeus vannamei. The cDNA of the L. vannamei Dmc1 homologue (LvDmc1) was 1,647 bp long and contained a 1,023-bp open reading frame corresponding to 341 amino acid residues. The deduced amino acid sequence contained motifs conserved in the RecA/Rad51 superfamily to which Dmc1 homologues belong and showed high identities with Dmc1 of other animals, including invertebrate and vertebrate species. RT-PCR revealed the presence of transcripts of LvDmc1 in gonads having meiotic germ cells. In situ hybridization analysis showed that LvDmc1 mRNA was abundantly expressed in premeiotic spermatogonia and oogonia, but not in gonadal somatic cells. LvDmc1 is thus a potentially useful indicator of the early stages of germ cell development.

Molecular Cloning and Characterization of Dmc1 from the Chinese Mitten Crab (Eriocheir sinensis)

“…This expression pattern would suggest EsDmc1 could be expressed at earlier developmental stages before reproductive maturity in E. sinensis. Contrary to the results from L. vannamei, P. monodon Dmc1 did not show gonad-specific expression [14][15][16], indicating the complex roles of Dmc1 in crustaceans. Further investigations regarding crab Dmc1, particularly functional studies, are needed to determine the biological roles of this gene in crustaceans.…”

“…EsDmc1 displayed 87.3% identity with published Dmc1 of L. vannamei (LvDmc1), 86.5% with P. monodon (PmDmc1), 77.4% with Ixodes scapularis (IsDmc1), 75.9% with Anguilla japonica (AjDmc1) and 74.8% with Homo sapiens (HsDmc1). As reported in LvDmc1 [16], multiple alignments revealed that EsDmc1 contained motifs conserved in the RecA/Rad51 superfamily, including L1 and L2 loops, which are single-strand DNA binding motifs [25,26], and the Walker A and B motifs of the ATP binding site [26,27] (Figure 3). Moreover, the helix-hairpin-helix (HhH) motif, a double-strand DNA binding site that is commonly present in Rad51 and Dmc1, but not in RecA [26,28,29], was also detected in EsDmc1.…”

“…The EsDmcl transcripts could be detected in all examined larval stages with the highest expression level in the fifth zoeal stage. These results suggest that EsDmc1 could be expressed before reproductive maturity and might have complex functions in crab reproduction.monodon [14,15] and whiteleg shrimp Litopenaeus vannamei [16]. Despite the finding of Dmc1 from testis transcriptome [17], no study has described the sequence characterization and expression pattern of Dmc1 in E. sinensis.…”

“…Most studies on expression profiles of Dmc1 transcripts have focused on the gonads and somatic tissues of adults or subadults [12,[14][15][16]. However, little is known about the expression pattern of Dmc1 in larval developmental stages.…”

“…monodon [14,15] and whiteleg shrimp Litopenaeus vannamei [16]. Despite the finding of Dmc1 from testis transcriptome [17], no study has described the sequence characterization and expression pattern of Dmc1 in E. sinensis.…”