Concerted evolution within a trypsin gene cluster in Drosophila

Area of Science:

• Genomics
• Molecular Evolution
• Drosophila melanogaster research

Background:

• A cluster of four trypsin genes was previously identified at position 47D-F in the Drosophila melanogaster genome.
• One gene was sequenced, and the others were detected via cross-hybridization.

Purpose of the Study:

• To present the complete DNA sequence of the genomic region encoding four trypsin genes.
• To identify and characterize a potential fifth trypsin gene within this cluster.
• To investigate the molecular evolution of this trypsin gene cluster by comparing it with a related species.

Main Methods:

• DNA sequencing of the genomic region encoding trypsin genes in Drosophila melanogaster.
• Isolation and sequencing of the homologous genomic region in Drosophila erecta.
• Comparative sequence analysis to infer evolutionary patterns.

Main Results:

• A fifth trypsin-coding sequence was identified within the gene cluster, showing over 30% divergence but retaining functional motifs.
• Comparative analysis with Drosophila erecta revealed evidence of concerted evolution among some gene family members.
• Differential evolutionary patterns were observed: two genes evolve in concert, one evolves independently, and two show intermediate evolution.

Conclusions:

• The trypsin gene cluster in Drosophila exhibits complex molecular evolution.
• A model involving chromosome looping and gene conversion is proposed to explain these evolutionary patterns.
• The findings provide insights into the dynamics of gene family evolution.