Abstract
Oocyte maturation and ovarian development are sequentially coordinated events critical to reproduction. In the ovaries of adult oviparous animals such as birds, bony fish, insects, and crustaceans, vitellogenin receptor (VgR) is a plasma membrane receptor that specifically mediates vitellogenin (Vg) transport into oocytes. Accumulation of Vg drives sexual maturation of the female crustaceans by acting as a pivotal regulator of nutritional accumulation within oocytes, a process known as vitellogenesis. However, the mechanisms by which VgR mediates vitellogenesis are still not fully understood. In this study, we first identified a unique VgR (Lv-VgR) and characterized its genomic organization and protein structural domains in Litopenaeus vannamei, a predominant cultured shrimp species worldwide. This newly identified Lv-VgR phylogenetically forms a group with VgRs from other crustacean species within the arthropod cluster. Duplicated LBD/EGFD regions are found exclusively among arthropod VgRs but not in paralogs from vertebrates and nematodes. In terms of expression patterns, Lv-VgR transcripts are specifically expressed in ovaries of female shrimps, which increases progressively during ovarian development, and rapidly declines toward embryonic development. The cellular and subcellular locations were For analyzed by in situ hybridization and immunofluorescence, respectively. The Lv-VgR mRNA was found to be expressed in the oocytes of ovaries, and Lv-VgR protein was found to localize in the cell membrane of maturing oocytes while accumulation of the ligand Vg protein assumed an even cytoplasmic distribution. Silencing of VgR transcript expression by RNAi was effective for stunting ovarian development. This present study has thus provided new insights into the regulatory roles of VgR in crustacean ovarian development.
Highlights
Ovarian development of oviparous animal comprises the stages of oogonia, previtellogenesis and vitellogenesis (Charniauxcotton, 1985)
The full-length cDNA of vitellogenin receptor (VgR) has been obtained from Pacific white shrimp L. vannamei (Supplementary Figure S1), with predictions of its corresponding gene structure (Figure 1A) and protein structural domains (Figure 1B)
The Class A, epidermal growth factor (EGF)-like and YWTD repeats present in almost all VgRs in oviparous animals, but the specific numbers for these repeats vary in different species (Figure 3B)
Summary
Ovarian development of oviparous animal comprises the stages of oogonia, previtellogenesis and vitellogenesis (Charniauxcotton, 1985). Vitellogenesis occurs as a key process for accumulation of proteins, fats and other nutrients. The size of oocytes expands rapidly by several hundred times after the inception of vitellogenesis, with a mass of nutrients accumulated (Chen et al, 2018a). Vitellogenin (Vg) is a protein precursor of vitellin, and it is considered to be synthesized, processed, transported, absorbed and forms the yolk (Wahli et al, 1981). In the case of exogenous Vg, the protein is transported through blood or hemolymph and absorbed into the oocytes through endocytosis mediated by vitellogenin receptor (VgR) (Li et al, 2001; Warrier and Subramoniam, 2002)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
