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Proc Biol Sci. 2005 Sep 22;272(1575):1935-40.

Sex as a response to oxidative stress: stress genes co-opted for sex.

Author information

1
Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 6E1. anedelcu@unb.ca

Abstract

Despite a great deal of interest, the evolutionary origins and roles of sex remain unclear. Recently, we showed that in the multicellular green alga, Volvox carteri, sex is a response to increased levels of reactive oxygen species (ROS), which could be indicative of the ancestral role of sex as an adaptive response to stress-induced ROS. To provide additional support for the suggestion that sex evolved as a response to oxidative stress, this study addresses the hypothesis that genes involved in sexual induction are evolutionarily related to genes associated with various stress responses. In particular, this study investigates the evolutionary history of genes specific to the sexual induction process in V. carteri--including those encoding the sexual inducer (SI) and several SI-induced extracellular matrix (ECM) proteins. Surprisingly, (i) a highly diversified multigene family with similarity to the V. carteri SI and SI-induced pherophorin family is present in its unicellular relative, Chlamydomonas reinhardtii (which lacks both a SI and an ECM) and (ii) at least half of the 12 identified gene members are induced (as inferred from reported expressed sequence tags) under various stress conditions. These findings suggest an evolutionary connection between sex and stress at the gene level, via duplication and/or co-option.

PMID:
16191600
PMCID:
PMC1559886
DOI:
10.1098/rspb.2005.3151
[Indexed for MEDLINE]
Free PMC Article

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