title: Identification and comparative analysis of the Tegillarca granosa haemocytes microRNA transcriptome in response to Cd using a deep sequencing approach.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are endogenous non-coding small RNAs (sRNAs) that can base pair with their target mRNAs, which represses their translation or induces their degradation in various biological processes. To identify miRNAs regulated by heavy metal stress, we constructed two sRNA libraries for the blood clam Tegillarca granosa: one for organisms exposed to toxic levels of cadmium (Cd) and one for a control group.
  
  
  RESULTS
  Sequencing of the two libraries and subsequent analysis revealed 215 conserved and 39 new miRNAs. Most of the new miRNAs in T. granosa were up- or down-regulated in response to Cd exposure. There were significant differences in expression between the Cd and control groups for 16 miRNAs. Of these, five miRNAs were significantly up-regulated and 11 were significantly down-regulated in the Cd stress library. Potential targets were predicted for the 16 differential miRNAs in pre-miRNAs identified according to sequence homology. Some of the predicted miRNA targets are associated with regulation of the response to stress induced by heavy metals. Five differentially expressed miRNAs (Tgr-nmiR-8, Tgr-nmiR-21, Tgr-miR-2a, Tgr-miR-10a-5p, and Tgr-miR-184b) were validated by qRT-PCR.
  
  
  CONCLUSIONS
  Our study is the first large-scale identification of miRNAs in T. granosa haemocytes. Our findings suggest that some miRNAs and their target genes and pathways may play critical roles in the responses of this species to environmental heavy metal stresses.
authors.affiliation: Zhejiang Key Laboratory of Aquatic Germplasm Resources, Zhejiang Wanli University, Ningbo, Zhejiang, China.
authors.forename: Yongbo
authors.initials: Y
authors.lastname: Bao
authors.affiliation: Zhejiang Key Laboratory of Aquatic Germplasm Resources, Zhejiang Wanli University, Ningbo, Zhejiang, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Zhejiang Key Laboratory of Aquatic Germplasm Resources, Zhejiang Wanli University, Ningbo, Zhejiang, China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Zhejiang Key Laboratory of Aquatic Germplasm Resources, Zhejiang Wanli University, Ningbo, Zhejiang, China.
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Lin
mesh_terms: D000818:Animals; D049893:Arcidae / Q000187:drug effects / Q000235:genetics*; D002104:Cadmium / Q000633:toxicity; D020869:Gene Expression Profiling; D006434:Hemocytes / Q000187:drug effects; D059014:High-Throughput Nucleotide Sequencing; D035683:MicroRNAs / Q000235:genetics*; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D035683:MicroRNAs; D002104:Cadmium