Transcriptome analysis of sika deer in China.

Sika deer is of great commercial value because their antlers are used in tonics and alternative medicine and their meat is healthy and delicious. The goal of this study was to generate transcript sequences from sika deer for functional genomic analyses and to identify the transcripts that demonstrate tissue-specific, age-dependent differential expression patterns. These sequences could enhance our understanding of the molecular mechanisms underlying sika deer growth and development. In the present study, we performed de novo transcriptome assembly and profiling analysis across ten tissue types and four developmental stages (juvenile, adolescent, adult, and aged) of sika deer, using Illumina paired-end tag (PET) sequencing technology. A total of 1,752,253 contigs with an average length of 799 bp were generated, from which 1,348,618 unigenes with an average length of 590 bp were defined. Approximately 33.2 % of these (447,931 unigenes) were then annotated in public protein databases. Many sika deer tissue-specific, age-dependent unigenes were identified. The testes have the largest number of tissue-enriched unigenes, and some of them were prone to develop new functions for other tissues. Additionally, our transcriptome revealed that the juvenile-adolescent transition was the most complex and important stage of the sika deer life cycle. The present work represents the first multiple tissue transcriptome analysis of sika deer across four developmental stages. The generated data not only provide a functional genomics resource for future biological research on sika deer but also guide the selection and manipulation of genes controlling growth and development.