Characterization and comparative profiling of MiRNA transcriptomes in bighead carp and silver carp

Area of Science:

• Genomics
• Molecular Biology
• Evolutionary Biology

Background:

• MicroRNAs (miRNAs) are crucial post-transcriptional regulators, but their transcriptomes in teleost fishes remain understudied.
• Previous research has focused on individual miRNAs, neglecting a comprehensive analysis of miRNA populations in fish.

Purpose of the Study:

• To identify and characterize conserved and novel microRNAs (miRNAs) in bighead carp (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix).
• To compare miRNA expression patterns and investigate potential regulatory functions and evolutionary dynamics of miRNA genes in these species.

Main Methods:

• High-throughput sequencing to identify conserved and novel miRNAs in bighead and silver carp.
• Hierarchical clustering analysis and log2 ratio to compare miRNA expression patterns.
• Computational strategies utilizing zebrafish genome and un-annotated data to discover novel miRNAs.

Main Results:

• Identified 167 conserved miRNAs in bighead carp and 166 in silver carp, belonging to 108 families.
• Observed varied expression patterns despite sequence conservation, with some miRNAs showing significant expression differences.
• Discovered novel miRNAs, including 8 and 22 potentially zebrafish-homologous miRNAs and 31-32 carp-specific miRNAs with low expression.
• Detected miRNA* sequences with potential regulatory functions and observed gain/loss of miRNA family members.

Conclusions:

• High-throughput sequencing provides a powerful tool for comprehensive miRNA transcriptome analysis in teleost fishes.
• MiRNA sequence conservation does not always correlate with expression conservation, indicating complex post-transcriptional regulation.
• The findings suggest evolutionary processes like gene duplication contribute to miRNA gene family expansion and diversification in fish.