Kasbekar, D.P. and Rekha, S. (2017) Neurospora tetrasperma crosses heterozygous for hybrid translocation strains produce rare eight-spored asci-bearing heterokaryotic ascospores. Journal of Biosciences, 42 (1). pp. 15-21. ISSN 0250-5991

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Abstract

During ascogenesis in Neurospora, the ascospores are partitioned at the eight-nucleus stage that follows meiosis and a post-meiotic mitosis, and the ascospores that form in eight-spored asci are usually homokaryotic. We had previously created novel TNt strains by introgressing four Neurospora crassa insertional translocations (EB4, IBj5, UK14-1, and B362i) into N. tetrasperma. We now show that crosses of all the TNt strains with single-mating-type derivatives of the standard N. tetrasperma pseudohomothallic strain 85 (viz. TNta x 85A or TNtA x 85a) can produce rare eight-spored asci that contain heterokaryotic ascospores, or ascospores with other unexpected genotypes. Our results suggest that these rare asci result from the interposition of additional mitoses between the post-meiotic mitosis and the partitioning of nuclei into ascospores, leading to the formation of supernumerary nuclei that then generate the heterokaryotic ascospores. The rare asci probably represent a background level of ascus dysgenesis wherein the partitioning of ascospores becomes uncoupled from the post-meiotic mitosis. Ordinarily, the severest effect of such dysgenesis, the production of mating-type heterokaryons, would be suppressed by the N. crassa tol (tolerant) gene, thus explaining why such dysgenesis remained undetected thus far

Item Type:	Article
Depositing User:	Users 2 not found.
Date Deposited:	27 Feb 2017 11:28
Last Modified:	27 Feb 2017 11:28
URI:	http://cdfd.sciencecentral.in/id/eprint/772

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