DEVELOPMENT OF INTERMUSCULAR BONE IN TELEOSTS

Intermuscular bone (IB), which occurs only in the myosepta of lower teleosts, is attracting more attention because they are difficult to remove and make the fish unpleasant to eat. By gaining a better understanding of the genetic regulation of IB development, an integrated analysis of miRNAs and mRNAs expression profiling was performed on one typical Cyprinidae species, blunt snout bream (Megalobrama amblycephala). Four key development stages related to IB's development were selected for transcriptome and small RNA sequencing. A number of significantly differentially expressed miRNAs/genes associated with bone formation and differentiation were identified and the functional characteristics of these miRNAs/genes were revealed by GO function and KEGG pathway analysis. These were involved in TGF-β, ERK and osteoclast differentiation pathways known in the literature to affect bone formation and differentiation. MiRNA-mRNA interaction pairs were detected from comparison of expression between different stages.

Besides IBs, ribs are also a part of skeletal system in teleosts, but IBs and ribs have different developing process. The chemical composition of fish IBs and ribs as well as the underlying mechanism about their development have not been investigated. In our study, histological structures showed that one bone cavity containing osteoclasts were existed in ribs, but not in IBs of M. amblycephala. We constructed the first proteomics map for fish bones including IBs and ribs, as well as to identify the differentially expressed proteins between IBs and ribs through iTRAQ LC-MS/MS proteomic analysis. The proteins extracted from IBs and ribs were quantified 2342 proteins, with 1451 proteins annotated with GO annotation in biological processes, molecular function and cellular component. A number of bone related proteins as well as pathways were identified in the study.

Our study provided the first comprehensive transcriptome and proteomics resources of intermuscular bone for teleosts.