Thorp Michael W, Chapman Eric J, Simmons Michael J
Department of Genetics, Cell Biology and Development, University of Minnesota, St. Paul, MN 55108-1095, USA.
Genet Res (Camb). 2009 Oct;91(5):327-36. doi: 10.1017/S001667230999022X.
Strains carrying the X-linked telomeric P elements TP5 or TP6 varied in their ability to repress hybrid dysgenesis. The rank ordering of these strains was consistent across different genetic assays and was not related to the type of telomeric P element (TP5 or TP6) present. Strong repression of dysgenesis was associated with weak expression of mRNA from the telomeric P element and also with a reduced amount of mRNA from a transposase-producing P element contained within a transgene inserted on an autosome. A strictly maternal component of repression, transmitted independently of the telomeric P element, was detected in the daughters but not the sons of females from the strongest repressing strains. However, this effect was seen only when dysgenesis was induced by crossing these females to males from a P strain, not when it was induced by crossing them to males homozygous for a single transposase-producing P element contained within a transgene. These findings are consistent with the hypothesis that the P cytotype, the condition that regulates P elements, involves an RNA interference mechanism mediated by piRNAs produced by telomeric P elements such as TP5 and TP6 and amplified by RNAs produced by other P elements.
携带X连锁端粒P因子TP5或TP6的菌株在抑制杂种不育的能力上存在差异。这些菌株的排名顺序在不同的遗传检测中是一致的，并且与所存在的端粒P因子的类型（TP5或TP6）无关。对杂种不育的强烈抑制与端粒P因子mRNA的弱表达相关，也与插入常染色体上的转基因中所含产生转座酶的P因子的mRNA量减少有关。在来自最强抑制菌株的雌性后代而非雄性后代中检测到一种严格的母系抑制成分，它独立于端粒P因子进行传递。然而，只有当通过将这些雌性与P品系的雄性杂交来诱导杂种不育时才会出现这种效应，而当通过将它们与转基因中所含单个产生转座酶的P因子纯合的雄性杂交来诱导杂种不育时则不会出现这种效应。这些发现与以下假设一致：调节P因子的P细胞型涉及一种RNA干扰机制，该机制由端粒P因子（如TP5和TP6）产生的piRNA介导，并由其他P因子产生的RNA进行扩增。
