Transcriptomic information from the ovaries of red swamp crayfish (Procambarus clarkii) provides new insights into development of ovaries and embryos

Abstract

The red swamp crayfish Procambarus clarkii is a commercially important aquaculture species in inland China. Currently, the major constraint on the crayfish industry is the shortage of high-quality juveniles. Understanding the mechanisms that regulate ovarian development and maturation in female P. clarkii is crucial for the resolution of this problem. Through RNA-Seq technology, we first obtained the deep-coverage transcriptome sequencing data from the ovary of P. clarkii. A total of 31, 080, 133 clean reads were retrieved after removing the adapters in reads and filtering out low-quality data. All reads were assembled into 69, 261 unigenes with N50 of 1, 129 bp, of which 24, 014 unigenes matched sequences in the GenBank non-redundant database. From this transcriptome data, we obtained the full-length of one fragment that was previously identified to be differently expressed between precocious and normally grown P. clarkii ovaries. This gene encodes a peptide which shared the highest identity with RDH11 from other species, thus it was named PcRDH11 (P. clarkii retinol dehydrogenase 11). qRT-PCR analysis showed that PcRDH11 was highly transcribed in the ovary at the late vitellogenic stage. In situ hybridization exhibited specific expression of PcRDH11 in follicular cells around the early oocytes, but in the late vitellogenic stage, it moved to the ooplasm. Knockdown of PcRDH11 by injection of double-stranded RNA (dsRNA) resulted in decreased transcription of vitellogenin (Vg) and vitellogenin receptor (VgR). Treatment of early embryos with dsPcRDH11 caused arrest of the embryonic development and death of embryos. These results suggest that PcRDH11 may play an important role in ovarian development and embryogenesis. Our data provide insights into the molecular regulatory mechanisms of ovarian development in P. clarkii and other crustaceans, and will be helpful for the development of new techniques for artificial regulation of the reproductive process in crayfish aquaculture.