# Caenorhabditis elegans brc-1 mutation increases the number of COSA-1 foci in him-8 and zim-2 mutants

## TL;DR

This study shows that a mutation in the brc-1 gene increases COSA-1 foci in specific mutants of C. elegans, affecting chromosome pairing and crossover formation.

## Contribution

The study reveals a novel role for brc-1 in regulating COSA-1 foci in mutants with pairing defects.

## Key findings

- zim-1 mutants show increased COSA-1 foci compared to expected levels.
- brc-1 mutation suppresses the excess COSA-1 foci in zim-1 mutants.
- brc-1 mutation increases COSA-1 foci in him-8 and zim-2 mutants during oogenesis.

## Abstract

Crossover designation factors such as
COSA-1
are concentrated at the specific DNA double-strand break (DSB) sites to promote crossover formation.

zim-1

mutants, which show defects in the homologous chromosome pairing of chromosomes II and III, increase the
COSA-1
foci/normal bivalent state compared to the expected value. The excess designation was suppressed by an additional mutation in

brc-1

in

zim-1

mutants. We demonstrated that the number of
COSA-1
foci in

him-8

and

zim-2

mutants, showing defects in the pairing of the X and V chromosomes, respectively, increased compared to the expected value, and

brc-1

mutation accelerated the number of
COSA-1
foci in oogenesis.