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RNA-Seq technology has been widely applied to transcriptomics, genomics and functional gene study. Here, we performed de novo transcriptome sequencing to produce 23,842,172 clean reads representing a total of 4,815,798,404 (4.8 Gb) nucleotides from comprehensive transcript dataset for testis of Coilia nasus. Over 20 million Illumina reads were assembled into 194,636 unigenes, and 42,642 annotated genes were predicted by Blastx and ESTScan, respectively. Applying Blast analysis and functional annotation (e.g., GO, COG, SwissProt and KEGG) using the assembled gene models from catalogs of other species, we have sampled an extensive and diverse expressed gene catalog for C. nasus representing a large proportion of the genes involved in the onset of spermatogenesis. The results will provide a general clue to the potential spermatogenesis molecular mechanisms for this species. [ABSTRACT FROM AUTHOR]

Coilia nasus is an anadromous kind of small to moderate size fish species, and limited transcriptomics research has been performed. In the present study, we performed Illumina sequencing to produce a 22,996,612 clean reads representing with a total of 4,599,079,601 (4.5 Gb) nucleotides comprehensive transcript dataset for ovary of C . nasus . Over 20 million total reads were assembled into 63,141 unigenes, and 27,027 annotated genes were predicted by Blastx and ESTScan, respectively. Applying Blast analysis and functional annotation (e.g., GO, COG, Swissprot and KEGG), we have sampled an extensive and diverse expressed gene catalog for C . nasus representing a large proportion of the genes expressed in the ovary development process. This approach will assist in the discovery and annotation of novel genes that play key roles in anadromous fish spawning migration process. [ABSTRACT FROM AUTHOR]

FoxL2 is a member of the forkhead/HNF-3-related family of transcription factors which provides tissue specific gene regulation. It is known to regulate ovarian aromatase, which plays a crucial role in ovarian development and mature. To understand the role of FoxL2/ovarian aromatase encoded gene Cyp19a1a during ovarian development and recrudescence, we identified cDNA characteristics of FoxL2 and Cyp19a1a, analyzed its temporal expression both at transcript and protein levels in the anadromous fish, Coilia nasus. Tissue distribution pattern revealed that FoxL2 mRNA expression level was highest in ovary, while Cyp19a1a mRNA was highest in brain. During the upstream migration cycle, in ovary, the FoxL2 mRNA temporal expression peaked at the multiplication stage (stage III in May), the Cyp19a1a mRNA expression peaked at the onset stage (stage I in March). It was found that their mRNA transcripts were maintained at high level during the migration stage (from stage I in March to stage VI in July). Additionally, the strongest immunolabeling positive signals of Cyp19a1a and FoxL2 proteins were mainly found in the cytoplasm of olfactory bulb cell, stratum granulare and neurogliocyte cells and development stage oocytes. Data indicated that FoxL2 and Cyp19a1a were inducible and functional in the C. nasus ovary development and migration process. Therefore, the present results can be regarded as evidence for indispensable roles of FoxL2 and Cyp19a1a in the ovary development and migratory behavior at gene expression patterns and encoded protein distribution level. • FoxL2 and cyp19a1a were first characterized in Coilia nasus. • FoxL2 and cyp19a1a were inducible and functional in the C. nasus ovary development. • FoxL2 and Cyp19a1a could act as a co-stimulator in teleosts anadromous migration. [ABSTRACT FROM AUTHOR]