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Open Access Research article

Characterisation of Caenorhabditis elegans sperm transcriptome and proteome

Xuan Ma1, Yingjie Zhu2, Chunfang Li2, Peng Xue3, Yanmei Zhao1, Shilin Chen2, Fuquan Yang3 and Long Miao1*

Author Affiliations

1 Laboratory of Non-coding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China

2 Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing 100094, China

3 Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China

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BMC Genomics 2014, 15:168  doi:10.1186/1471-2164-15-168

Published: 28 February 2014

Abstract

Background

Although sperm is transcriptionally and translationally quiescent, complex populations of RNAs, including mRNAs and non-coding RNAs, exist in sperm. Previous microarray analysis of germ cell mutants identified hundreds of sperm genes in Caenorhabditis elegans. To take a more comprehensive view on C. elegans sperm genes, here, we isolate highly pure sperm cells and employ high-throughput technologies to obtain sperm transcriptome and proteome.

Results

First, sperm transcriptome consists of considerable amounts of non-coding RNAs, many of which have not been annotated and may play functional roles during spermatogenesis. Second, apart from kinases/phosphatases as previously reported, ion binding proteins are also enriched in sperm, underlying the crucial roles of intracellular ions in post-translational regulation in sperm. Third, while the majority of sperm genes/proteins have low abundance, a small number of sperm genes/proteins are hugely enriched in sperm, implying that sperm only rely on a small set of proteins for post-translational regulation. Lastly, by extensive RNAi screening of sperm enriched genes, we identified a few genes that control fertility. Our further analysis reveals a tight correlation between sperm transcriptome and sperm small RNAome, suggesting that the endogenous siRNAs strongly repress sperm genes. This leads to an idea that the inefficient RNAi screening of sperm genes, a phenomenon currently with unknown causes, might result from the competition between the endogenous RNAi pathway and the exogenous RNAi pathway.

Conclusions

Together, the obtained sperm transcriptome and proteome serve as valuable resources to systematically study spermatogenesis in C. elegans.

Keywords:
C. elegans; Sperm; Transcriptome; Proteome