Identification and Characterization of a Novel Microvitellogenin from the Chinese Oak Silkworm Antheraea pernyi
Yanqun Liu1, Miaomiao Chen2, Junfang Su3
1Department of Sericulture, Shenyang Agricultural University, Shenyang, Liaoning, China; Sericultural Institute of Liaoning Province, Fengcheng, Liaoning, China.
Abstract:
Microvitellogenin (mVg) is a relatively small vitellogenic protein only characterized in the eggs of the lepidopteran insects Manduca sexta and Bombyx mori. In the present study, we report a novel mVg (ApmVg) isolated from the Chinese oak silkworm Antheraea pernyi. The obtained ApmVg cDNA sequence contains an open reading frame of 783 bp encoding a protein of 260 amino acids with a predicted molecular weight of 29.96 kDa. This gene does not contain introns. Structural analysis revealed that this protein shares putative conserved domains with the lepidopteran low-molecular weight lipoprotein, which belongs to the lipoprotein_11 superfamily. The protein sequence of ApmVg exhibits 48% sequence identity with mVg from M. sexta and 40-47% sequence identity with the 30K lipoproteins from B. mori. Phylogenetic analysis suggests that ApmVg is a novel member of the lepidopteran low-molecular weight lipoproteins. Transcriptional analysis indicated that ApmVg mRNA is mainly expressed in the fat body (both female and male) during post-diapause development of the pupal stage, and it was also detected in ovaries and spermaries in smaller amounts. RT-PCR and Western blot analyses revealed that ApmVg is synthesized by the fat body and secreted into hemolymph and ultimately accumulates in eggs. The ApmVg transcript can be detected in the fat bodies of female pupae four days after treatment with 20-hydroxyecdysone and shows an expression pattern distinct from that of vitellogenin (Vg), which is detectable throughout diapausing and in post-diapause development. ApmVg decreased dramatically during embryonic development. These results represent the first study of mVg outside M. sexta and B. mori and provide insight into the physiological role and evolution of mVgs.
Insights
Researchers identified a new microvitellogenin (mVg) in the Chinese oak silkworm, Antheraea pernyi. This novel protein, ApmVg, is synthesized in the fat body and accumulates in eggs, offering new insights into lepidopteran insect reproduction.
Area of Science:
- Insect Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Microvitellogenin (mVg) is a small vitellogenic protein previously identified only in Manduca sexta and Bombyx mori.
- Understanding mVg diversity is crucial for insect reproductive biology and evolution.
Purpose of the Study:
- To identify and characterize a novel mVg in the Chinese oak silkworm, Antheraea pernyi.
- To investigate the expression patterns and potential functions of this new mVg.
Main Methods:
- cDNA sequencing and analysis to determine the ApmVg gene and protein structure.
- Phylogenetic analysis to establish evolutionary relationships.
- Transcriptional analysis (RT-PCR) and protein detection (Western blot) to study expression and localization.
Main Results:
- A novel mVg, ApmVg, was isolated from Antheraea pernyi, with a predicted size of 29.96 kDa.
- ApmVg shares conserved domains with other lepidopteran low-molecular-weight lipoproteins and exhibits significant sequence identity with known mVgs.
- ApmVg mRNA is primarily expressed in the fat body during post-diapause pupal development and is secreted into hemolymph, accumulating in eggs.
- ApmVg expression is regulated by 20-hydroxyecdysone and differs from vitellogenin (Vg) expression patterns, decreasing during embryonic development.
Conclusions:
- ApmVg represents the first characterized mVg outside of M. sexta and B. mori, expanding the known diversity of these proteins.
- The findings provide insights into the physiological role of mVgs in Antheraea pernyi reproduction and their evolutionary history within Lepidoptera.
