Comparative Transcriptome Of Prothoracic Glands From Two Silkmoths Antheraea Pernyi And Bombyx Mori

The prothoracic gland(PG)is one of the most important endocrine organ of synthesis and secretion of ecdysteroids that play critical roles in regulating growth,moulting and metamorphosis of insects.Yet,advances in understanding this important organ at the molecular level have been severely limited because basic genomic information is lacking.To fill this gap,here,we used a comparative transcriptomic approach to characterize the PGs from two economically important insect species,domesticated silkworm Bombyx mori and wild silkworm Antheraea pernyi.Based on the transcriptome data obtained here,we identified a set of genes involved in circadian clock in the two PGs.Furthermore,simple sequence repeats(SSRs)were also detected and analyzed in A.pernyi transcriptome.The results provide extremely valuable information resources for insight into the understanding of the characteristics and functions of this important endocrine organ.The main results are as follows.1.The transcriptome sequencing and comparative analysis of Antheraea pernyi and Bombyx mori PG.A reference-based transcriptome assembly for B.mori is generated containing 49,287 transcripts(average length of 1064 bp)derived from 32,303 Unigenes,and a de novo transcriptome assembly for A.pernyi is generated containing 64,301 transcripts(average length of 657 bp)derived from 44,067 Unigenes.The data of Antheraea pernyi and Bombyx mori have been deposited in the NCBI Sequence Read Archive.Registration number is SRR5119598 and SRR5119600,respectively.A total of 22,402 and 23,157 Unigenes have matched homologous hits in A.pernyi and B.mori PG transcriptome,respectively.Comparative analysis indicates the two PG transcriptomes shared an overall similarity based on the distribution of GO terms?COG category and KO assignments.Furthermore,6,357 pairs of the orthologous genes are identified between A.pernyi and B.mori PG transcriptomes.2.The identification and RT-PCR detection of circadian clock genes.The circadian clock plays an important role in regulating the behavior and physiology of insects.13 circadian clock genes are identified from the transcriptome data of A.pernyi and B.mori,including cryptochrome 1?cryptochro,me 2?period.timeless?clock?cycle?shaggy?double-time?vrille?PAR-domain protein 1?slimb?casein kinase ?alpha?casein kinase ?beta.The result of RT-PCR test shows that these genes are expressed in the PG.These results suggest that there is also a peripheral clock in PG of insects.3.The SSR analysis in Antheraea pernyi.A total of 2322 SSRs that occurred in 1615 Unigenes are identified in the transcriptome data of A.pernyi,and the frequency of these SSRs is 37.60%and mean distance is 4.76 kb in the Unigenes.The mononucleotide repeat are the most abundant SSRs detected.The transcriptome data obtained provide the information basis for the design of SSR primers.And it further provides foundations for genetic diversity analysis,functional gene discovery and genetic map structure for Antheraea pernyi.