Characterising alternate splicing and tissue specific expression in the chicken from ESTs.

Area of Science:

• * Genomics and Molecular Biology
• * Transcriptomics and Gene Expression Analysis
• * Avian Biology

Background:

• * Alternative splicing is a key mechanism generating transcriptomic complexity in eukaryotes.
• * Understanding alternative splicing in avian species is crucial for comparative genomics.
• * Previous large-scale analyses have been limited in non-mammalian vertebrates.

Purpose of the Study:

• * To analyze alternative splicing events in the chicken genome using extensive EST data.
• * To quantify the extent of alternative splicing and estimate novel transcripts.
• * To compare chicken alternative splicing patterns with other higher vertebrates.

Main Methods:

• * Mapped over 580,000 chicken EST sequences to the recently sequenced chicken genome.
• * Utilized the EXONERATE program with the est2genome model for EST-to-genome mapping.
• * Implemented rigorous quality control steps to filter erroneous mapping results.
• * Characterized splicing events at the exon level to classify events and identify novel transcripts.

Main Results:

• * Estimated that 50-60% of the chicken gene set undergoes alternative splicing.
• * Calculated an average of approximately 2.3 transcripts per gene for alternatively spliced genes.
• * Found that chicken alternative splicing levels are comparable to those in humans and mice.
• * Identified tissue-specific gene and transcript usage, highlighting genes like twinfilin-2 and embryonic heavy chain myosin.
• * Discovered several unannotated genes important in embryonic tissues exhibiting alternative splicing.

Conclusions:

• * Chicken exhibits a significant level of alternative splicing, comparable to other higher vertebrates.
• * The study provides the first large-scale analysis of alternative splicing in an avian species.
• * EST data is valuable for characterizing alternative splicing but requires broad tissue representation and large transcript datasets.
• * Identified novel and potentially important alternatively spliced genes in chicken embryonic tissues.