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University of Iowa News Release


Nov. 3, 2006

UI Biologist Receives $347,340 Carver Grant To Study Sex And Meiosis In Fungi

John M. Logsdon Jr., assistant professor in the UI College of Liberal Arts and Sciences Department of Biological Sciences and the Roy J. Carver Center for Comparative Genomics, has received a three-year, $347,340 grant from the Roy J. Carver Charitable Trust to study the evolution of sex and meiosis in fungi.

The study would be an important milestone in understanding sexual reproduction by providing the first comprehensive analysis of the evolution of genes needed for sex in eukaryotes. Eukaryotes are cells with nuclei, including those found in plants, animals and fungi.

In a previous study, Logsdon and his colleagues investigated a single-celled parasite (Giardia intestinalis, an organism that causes diarrhea in animals and humans) thought to represent one of the most ancient branches on the eukaryotic tree of life. Although Giardia had long been thought to reproduce asexually, the organism was found to have five genes used in meiosis (the sexual process that halves an organism’s chromosomes to make gametes, such as sperm and eggs), thus suggesting that it is capable of sex and that the earliest such cells diverged after this process arose.

Logsdon says that the central goal of this new research is to study the evolution of meiotic genes essential for sex in fungi -- the closest relatives to animals on the tree of life. In previous research projects, several fungal species have served as model systems for studies of the mechanisms of meiosis and sex, yielding detailed knowledge of the genes required and their mechanisms of action.

“Over the past few years, almost 50 fungal genomes have been sequenced,” Logsdon says. “In this project, we will use available fungal genomes to find and characterize all of the genes that are known to be involved in the process of meiosis and which are essential for sex. For these meiotic genes, we will compare their sequences and determine their evolutionary histories. Our analyses will allow us to correlate evolutionary changes in these fungal genes to differences and similarities in sexual reproduction.”

He adds that the project also will isolate and analyze a subset of 10 of these meiotic genes from 20 additional fungal species representing key fungal groups whose genomes are not being sequenced. In several of these species, sex has not been observed. “If we find meiotic genes in these asexual species, we will determine if the genes are actually expressed and under what conditions,” Logsdon says.

“These results will provide the first comprehensive analysis of the evolution of genes needed for sex in any eukaryotic kingdom,” he adds. “It will also provide clear genetic evidence to determine if some fungi thought to be asexual are actually capable of sex.”

Logsdon and his colleagues plan to study other species in which sex has not been documented in order to learn whether meiosis is a requirement of all eukaryotes.

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