Identification of differentially expressed genes in the thoracic ganglion of the mud crab, Scylla paramamosain during ovarian maturation

Abstract

The thoracic ganglion is an important neuroendocrine organ in crabs. In order to isolate and clone differentially expressed genes in the thoracic ganglion of the mud crab, Scylla paramamosain, during ovarian maturation, a forward suppression subtractive hybridization cDNA library was constructed (crabs at maturation stage were used as the 'tester' and those at an early developmental stage as the 'driver'). cDNA obtained from suppression subtractive hybridization was inserted into an expression vector and was transferred into Escherichia coli. A total of 500 randomly selected clones were sequenced and 410 expressed sequence tags (ESTs) were obtained. The inserted fragment size was from 200 to 1500 bp. The insertion rate was up to 82%. This confirmed the successful construction of the library. The ESTs were recognized based on the BLAST searches in NCBI, clustered and assembled, annotated and finally categorized. Among the total of 139 genes, 124 genes (89.2%) were similar to known genes, while 15 genes (10.8%) were classified as a group of unknown function. This study accumulated a cohort of data for further research of functional genes in the thoracic ganglion.