Molecular Characterization of a cDNA Encoding Vitellogenin and Its Expression in the Hepatopancreas and Ovary during Vitellogenesis in the Kuruma Prawn, Penaeus japonicus

Abstract

In Crustacea, reproductive function and mechanisms regulating vitellogenesis have not been fully elucidated. This is due in great part to a lack of information concerning the biochemical nature of the vitellogenin molecule, the hemolymph precursor of yolk protein, vitellin, as well as the functional expression of the vitellogenin-encoding gene. We have therefore cloned a cDNA encoding vitellogenin in the kuruma prawn, Penaeus japonicus based on the N-terminal amino acid sequence of the 91 kDa subunit of vitellin. The open reading frame of this cDNA encoded 2,587 amino acid residues. This is the first investigation reporting a full-length cDNA and its corresponding amino acid sequence for vitellogenin in any crustacean species.Northern blot analysis and in situ hybridization have revealed that mRNA encoding vitellogenin was expressed in both the follicle cells in the ovary and the parenchymal cells in the hepatopancreas. In nonvitellogenic females, vitellogenin mRNA levels were negligible in both the ovary and hepatopancreas, but in vitellogenic females, levels were dramatically increased in both tissues. In the ovary, highest levels were observed during the early exogenous vitellogenic stage, and thereafter rapidly decreased, whereas in the hepatopancreas, high levels were maintained until the onset of the late vitellogenic stage. Differing profiles of vitellogenin mRNA levels in the ovary and hepatopancreas suggest that the contribution of these tissues to vitellogenin synthesis harbor separate and complementary roles during vitellogenesis.

Molecular diversity and evolution of the large lipid transfer protein superfamily

“…Additional sequences of LLTPs from arachnids may help define the context of the divergence of M-177. Importantly, the Vtg of decapodan Crustacea is not directly related to the Vtg genes of other taxons, as assumed by others (52)(53)(54)(55)(56)(57)(58)(59)(60), but is an apoB-like LLTP. This observation explains previous phylogenetic analyses on Vtgs only (57,62,69,70), in which decapodan Vtg failed to group with other invertebrate Vtgs.…”

“…In another class of arthropods, the decapodan Crustacea (e.g., lobster, crayfish, crab, shrimp), two distinct LLTPs have been identified, a CP (7,8) and a yolk protein named Vtg (52)(53)(54)(55)(56)(57)(58)(59)(60). Although both LLTPs have been identified only in distinct species, the relatively close relationship among these species as well as the divergence of the identified proteins strongly suggest that the subset of LLTPs present in decapodan Crustacea con-sists at least of one CP and one Vtg.…”

“…In view of the presence of other Vtg-like LLTPs in insects (e.g., Vtgs), MEP appears to originate from a duplicated Vtg gene that has been retained as a result of the acquisition of a novel function. CP, the single Vtg-like LLTP identified in decapodan Crustacea to date, may represent another example of neofunctionalization, as this protein functions as the major hemolymph coagulogen rather than as a yolk protein (7,8,50,52,53). In the same taxon, an apoB-like LLTP, named Vtg, constitutes the major yolk protein, rather than a Vtg-like LLTP as in most animals.…”

Intestinal water absorption through aquaporin 1 expressed in the apical membrane of mucosal epithelial cells in seawater-adapted Japanese eel

“…RNA extraction and northern blot analysis were carried out as described above. Hybridization signals were quantified as described previously (Tsutsui et al, 2000). The highest mRNA level determined in the posterior intestine of a seawater eel was designated an arbitrary value of 100.…”

Perspectives on Hormonal Manipulation of Shrimp Reproduction

“…Based on expression of vitellogenin mRNA, the vitellogenin synthesis sites have been determined as ovaries and hepatopancreas in Mar. japonicus by Tsutsui et al 25 , and as hepatopancreas in Mac. rosenbergii by Yang et al 29 .…”