Yeadon P J, Catcheside D E
School of Biological Sciences, Flinders University, Adelaide, South Australia.
Genetics. 1998 Jan;148(1):113-22. doi: 10.1093/genetics/148.1.113.
Multiple polymorphisms distinguish Emerson and Lindegren strains of Neurospora crassa within the histidine-3 gene and in its distal flank. Restriction site and sequence length polymorphism in a set of 14 PCR products covering this 6.9-kb region were used to identify the parental origin of DNA sequence information in prototrophic progeny of crosses heterozygous for auxotrophic mutations in his-3 and the silent sequence differences. Forty-one percent of conversion tracts are interrupted. Where the absence of rec-2+ permits activity of the recombination hotspot cog, conversion appears to originate at cog and conversion tracts are up to 5.9 kb long. The chromosome bearing cog(L), the dominant allele that confers a high frequency of recombination, is almost invariably the recipient of information. In progeny from crosses heterozygous rec-2/rec-2+, conversion tracts are much shorter, most are not initiated at cog and either chromosome seems equally likely to be converted. Although 32% of his-3 prototrophs have a crossover that may be associated with conversion, it is suggested that the apparent association between conversion and crossing over at this locus may be due to confounding of coincidental events rather than to a mechanistic relationship.
多个多态性区分了粗糙脉孢菌的艾默生菌株和林德格伦菌株的组氨酸-3基因及其侧翼远端。利用覆盖这个6.9kb区域的14个PCR产物中的限制性酶切位点和序列长度多态性，来确定在组氨酸-3中营养缺陷型突变杂合的杂交后代原养型子代中DNA序列信息的亲本来源以及沉默序列差异。41%的转换片段被打断。在缺乏rec-2+从而允许重组热点cog发挥活性的情况下，转换似乎起源于cog，转换片段长达5.9kb。携带cog(L)（赋予高重组频率的显性等位基因）的染色体几乎总是信息的接受者。在rec-2/rec-2+杂合杂交的后代中，转换片段要短得多，大多数不是从cog起始的，而且两条染色体似乎被转换的可能性相同。虽然32%的组氨酸-3原养型有一个可能与转换相关的交叉，但有人认为，在这个位点上转换与交叉之间明显的关联可能是由于偶然事件的混淆，而不是由于机制上的关系。
