Sim4cc

Sim4cc performs cross-species spliced alignment of expressed sequence tags (ESTs), cDNA and genomic sequences to support gene identification and annotation in newly sequenced genomes.

Key Features:

• Universal Spaced Seeds: Incorporates universal spaced seeds to increase alignment sensitivity across diverse evolutionary distances.
• Powerful Splice Signal Models: Employs splice signal models to improve identification of splice junctions for gene model prediction.
• Evolutionarily-Aware Alignment Techniques: Uses alignment techniques sensitive to evolutionary changes to align distantly related sequences.
• Comparison Modes: Supports one-to-one and one-to-many comparisons between genomic and cDNA/EST sequences.
• Performance: Demonstrates sensitivity more than 10% higher than competing spliced aligners in vertebrate comparisons while maintaining speed comparable to sim4.

Scientific Applications:

• Comparative Genomics: Enables cross-species alignment for comparative analyses of gene structure and conservation.
• Functional Genomics: Aids mapping of ESTs and cDNA to genomes to infer exon–intron structures and transcript models.
• High-throughput Annotation: Applicable in large-scale annotation pipelines, exemplified by mapping 64,000 Fagus grandifolia ESTs and unigenes to the poplar genome.
• Gene Annotation of New Genomes: Facilitates identification and annotation of genes in newly sequenced genomes via cross-species cDNA comparisons.

Methodology:

Combines universal spaced seeds, splice signal models, and evolutionarily-aware alignment techniques; tested on vertebrate comparisons across diverse evolutionary distances, showing >10% higher sensitivity than competitors and runtime comparable to sim4.