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Senescence in fungi: the view from Neurospora

Maheshwari, Ramesh and Navaraj, Arunasalam (2008) Senescence in fungi: the view from Neurospora. In: FEMS Microbiology Letters, 280 (2). pp. 135-143.

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Some naturally occurring strains of fungi cease growing through successive subculturing, i.e., they senesce. In Neurospora, senescing strains usually contain intramitochondrial linear or circular plasmids. An entire plasmid or its part(s) integrates into the mtDNA, causing insertional mutagenesis. The functionally defective mitochondria replicate faster than the wild-type mitochondria and spread through interconnected hyphal cells. Senescence could also be due to spontaneous lethal nuclear gene mutations arising in the multinucleated mycelium. However, their phenotypic effects remain masked until the nuclei segregate into a homokaryotic spore, and the spore germinates to form a mycelium that is incapable of extended culturing. Ultimately the growth of a fungal colony ceases due to dysfunctional oxidative phosphorylation. Results with senescing nuclear mutants or growth-impaired cytoplasmic mutants suggest that mtDNA is inherently unstable, requiring protection by as yet unidentified nuclear-gene-encoded factors for normal functioning. Interestingly, these results are in accord with the endosymbiotic theory of origin of eukaryotic cells.

Item Type: Editorials/Short Communications
Publication: FEMS Microbiology Letters
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Keywords: Neurospora;aging;senescence;mitochondria;mtDNA;plasmids.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 30 Mar 2010 12:23
Last Modified: 19 Sep 2010 05:58
URI: http://eprints.iisc.ac.in/id/eprint/26703

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