Meiotic silencing by unpaired DNA is expressed more strongly in the early than the late perithecia of crosses involving most wild-isolated Neurospora crassa strains and in self-crosses of N. tetrasperma
Meiotic silencing by unpaired DNA is expressed more strongly in the early than the late perithecia of crosses involving most wild-isolated Neurospora crassa strains and in self-crosses of N. tetrasperma
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DOI：
10.1016/j.fgb.2011.10.002
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发表时间：
2011-12-01
影响因子：
3
通讯作者：
Kasbekar, Durgadas P.
中科院分区：
文献类型：
--
作者：
Ramakrishnan, Mukund;Sowjanya, T. Naga;Kasbekar, Durgadas P.
未配对DNA的减数分裂沉默是一种假定的rnai介导的消除减数分裂中没有正确配对的同源基因的转录本的过程。根据与：：bml (r)和：：mei-3试验菌株杂交的β -微管蛋白（bml）和mei-3基因减数分裂沉默的表观强度，将80株粗神经孢子虫野生分离株分为3种类型。“OR”型和“Sad”型野生分离株分别沉默或不沉默这两个基因，而“Esm”型（68株）沉默bml而不沉默mei-3(+)，表明沉默强度中等。许多野生菌株，特别是Esm型菌株，与染色体片段重复Dp（EB4）值为148 kbp的菌株杂交可育，但与染色体片段重复Dp（lBj5）值为405 kbp的菌株杂交不育。较大的Dps可能包含更多的基因，这些基因对沉默的敏感性与bml相当，因此它们与OR型和Esm型菌株的杂交将同样不育，而较小的Dps，可能只有很少或没有bml型基因，在与Esm和Sad菌株的杂交中几乎没有基因沉默，因此仍然具有可育性。我们利用与Esm型菌株杂交的棒棒糖形腹膜作为沉默指标，以及四asperma神经孢子虫异位插入asm-1基因的杂合自交的白色孢子腹膜，发现这些杂交的减数分裂沉默在早期表达更强烈，而在晚期表达不强烈。(C) 2011爱思唯尔公司版权所有。
Meiotic silencing by unpaired DNA is a presumed RNAi-mediated elimination of the transcripts of any gene that is not properly paired with a homolog in meiosis. Eighty wild-isolated strains of Neurospora crassa were classified into three types based on the apparent strength of meiotic silencing of the bml (beta-tubulin) and mei-3 genes in crosses with the ::Bml(r) and ::mei-3 tester strains. "OR" and "Sad" type wild-isolates, respectively, did or did not silence both the genes, whereas the "Esm" type (68 strains) silenced bml but not mei-3(+), suggesting an intermediate strength of silencing. Many wild strains, especially of the Esm type, gave fertile crosses with strains bearing the 148 kbp chromosome segment duplication Dp(EB4) but their crosses with the 405 kbp Dp(lBj5) were barren. Larger Dps might include more genes whose sensitivity to silencing is comparable with that of bml, consequently their crosses with the OR and Esm type strains would be about equally barren, whereas small Dps, with presumably few or no bml-like genes suffer little gene silencing in crosses with Esm and Sad strains and thus remain fertile. Using lollipop-shaped asci as indicators of silencing in crosses of the ::act tester with Esm type strains, and white-spored asci in Neurospora tetrasperma self-crosses heterozygous for an ectopic insertion of the asm-1 gene, we found that meiotic silencing was expressed more strongly in the early but not in the late perithecia of these crosses. (C) 2011 Elsevier Inc. All rights reserved.