Molecular cloning and characteristics of DnaJa1and DnaJb1 in Coilia nasus: possible function involved in oogenesis during spawning migration.

Coilia nasus oogenesis/spawning migration is a well-defined synchronous arrangement process. DnaJs are indispensable molecular chaperones for oogenesis process. However, how DnaJs involved the anadromous spawning migration mechanism is outstanding and plausible. In this regard, two DnaJs (Cn-DnaJa1 and Cn-DnaJb1) are cloned from the Coilia nasus's ovary. Their structure both contains J domain, G/F domain and ZF domain. Their mRNA transcripts were found extensively expressed in all the sampled tissues and significantly highly in gonads, which probably mean that DnaJs involved in C. nasus's gonad development basal metabolic processes. In the process of spawning migration, Cn-DnaJa1 and Cn-DnaJb1 mRNA transcripts were also expressed with significant differences during oogenesis with highest levels in the development phase, and maintaining high levels during the multiplication, mature and spawning phase. Further study showed that the DnaJa1and DnaJb1protein have high distribution in the onset phase and mainly distributed in the oocyte cytoplasm especially during the migration development phase's. This experiment study demonstrated that DnaJs participate in reproductive regulation during the spawning migration process in C. nasus and possibly play a vital role in the ovary development process. These findings also provided a base knowledge for further molecular mechanism study of spawning migration.