Comparative transcriptome sequencing analysis of the narrow-clawed crayfish Pontastacus leptodactylus (Eschscholtz, 1823) and discovery of candidate sex-related genes

The comparative analysis of the gonads transcriptomes of the narrow-clawed crayfish Pontastacus leptodactylus were conducted to screen for sex-differentiation related genes based on Illumina RNA-seq technology. The transcriptome sequencing of cDNA libraries generated 543 million clean reads, and the N50 and mean length of the identified 59,348 unigenes were 1205 and 746 bp, respectively. A total of 4875 differentially expressed genes (DEGs) were obtained between the two sexes, of which 1627 predicted to be up-regulated in ovaries and 3248 in testes. A total of 86 candidate genes known to be associated with sexual differentiation and development were searched in the transcriptome of P. leptodactylus. Our results showed that the highly expressed male-related genes (dmrt1, amh, gsdf, spata 1, spata 13, spata 2, srm and smox) were significantly up -regulated to a substantial degree, suggesting the potential roles of these genes in gonads of P. leptodactylus. In addition, 11,989 potential simple sequence repeats (SSRs) and 190,655 putative single nucleotide polymorphisms (SNPs) were detected. The putative DEGs between the gonads provide an important source of information for further study of the sex-differentiation related genes in P. leptodactylus as well as development of molecular markers.