Emeritus Professor David Catcheside

Contact Details

Key Responsibilities

• Professor of Biological Sciences

Teaching

• Molecular Biology, Genetics and Genomics, Biodiversity of fungi

Research

Gene conversion of a fluorescent marker in Neurospora

We have identified and cloned genes that regulate the frequency of genetic recombination in specific regions of the chromosomes of the filamentous fungus Neurospora crassa. We have also found extensive natural DNA sequence polymorphisms within and between gene loci. Together, these provide a set of tools for investigating the molecular mechanism of genetic recombination and its control within meiotic cells. We have focused on recombination hotspots close to the his-3 and am loci. Using molecular tags within and nearby these genes, we have found that progeny which experienced a conversion event at his-3, which is near the strong recombination hotspot cog, frequently also have a crossover in the flanking region. In contrast, conversion events at am initiated by a weak recombination hotspot rarely experience associated crossovers, suggesting there may be no direct mechanistic relationships between these two types of recombination. Other recent findings are that 1) the DNA repair synthesis that leads to conversion events probably makes several excursions between the homologous chromosomes, giving rise to progeny with several patches of sequence derived from the homologue, 2) recombination events can pass several kb of total sequence mismatch in the homologous chromosomes and 3) that conversion events are initiated at the cog recombination hotspot in at least 30% of meiotic cells and may extend over as much as 14 kb of DNA sequence. Our current focus is on mapping recombination in octads at high resolution using molecular genetic and fluorescent markers and characterisation of the effect of specific gene knockouts on recombination.

Directed evolution of proteins: We have developed the cog recombination hotspot for gene shuffling in vivo. This allows the generation of novel proteins with a broad range of applications such as industrial enzymes and synthesis of novel drugs. We currently have collaborations with other laboratories to create novel proteins.

Biodiversity of Macrofungi in South Australia – a collaboration with Pam Catcheside, Honorary Research Associate at the South Australian Plant Biodiversity Centre, seeks to document the biodiversity of this Cinderella group in South Australia. The larger fungi are crucial to ecosystems where they play a major role in recycling of wood and other organic matter and form symbiotic mycorrhizal associations essential for the well-being of an estimated 90-95% of all trees and other plants. Despite their ecological importance, the macrofungi in South Australia have received little attention in comparison with plants and animals, with only one major study, conducted by Professor JB Cleland in the early part of the last century, which established a collection that provides a valuable resource for taxonomists. We are extending the range of habitats surveyed and depositing our collections in the Plant Biodiversity Centre. Reports of our findings, together with species descriptions can be obtained from the South Australian Department for Environment and Heritage.

Current members of the Laboratory

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