微卫星标记在不同壳色虾夷扇贝家系亲权鉴定的适用性
THE APPLICABILITY ANALYSIS ON MICROSATELLITE MARKERS FOR PARENTAGE DETERMINATION OF DIFFERENT SHELL COLOR LINES OF JAPANESE SCALLOP PATINOPECTEN YESSOENSIS
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摘要: 实验选取8 个多态性微卫星位点, 用于虾夷扇贝4 个不同壳色全同胞和半同胞家系160 个子代的亲权鉴定。在亲本未知和一亲本已知的情况下, 8 个微卫星位点累积排除概率分别为0.823 和0.961。鉴于亲权分析时子代的亲本在已知和未知情况下位点的累积排除概率不同, 实验采用了两种方法用于家系的亲权鉴定。方法1: 当子代的父母本情况未知时, 根据子代基因型数据, 通过CERVUS 2.0 软件计算子代所对应的候选亲本的LOD 值, 直接将候选亲本中具有最大的两个LOD 值的亲本确定为子代的父母本; 方法2: 在子代的亲本未知情况下, 视具有最大LOD 值的候选亲本为子代的第一候选亲本, 然后将该亲本视为已知, 通过CERVUS 2.0 软件重新计算每个侯选亲本的LOD 值, 再从中选择具有最大LOD 值的候选亲本作为该子代的第二候选亲本。结果表明, 采用方法2 得到的家系亲权鉴定成功率达到95%以上, 确定了微卫星标记在虾夷扇贝家系鉴定中的可行性。所检测的微卫星位点在子代中出现无效等位基因现象, 而无效等位基因存在会引起子代与亲本的错配。实验在家系鉴定时采用了无效等位基因存在(情况1)和缺失(情况2)两种子代基因型文件进行分析, 不同情况下同一方法家系鉴定成功率相差无几。这表明了基于多个微卫星位点计算候选亲本LOD 值大小寻找子代真实父母本可以降低由无效等位基因引起的错配的几率。研究表明了微卫星标记适合于不同壳色虾夷扇贝家系亲权鉴定工作。Abstract: 8 polymorphic microsatellite loci were selected for parentage determination on different shell color lines of Patinopecten yessoensis. 3 full-sib families and 1 half-sib family of P. yessoensis, each with 40 individuals, their parents were subjected to microsatellite analysis. The value of the total exclusionary power of 8 loci was 0.823 with the parents were unknown; when a typed single parent was known, the value of the total exclusionary power of 8 loci was 0.961. Two methods were used to analyze the parentage determination of all the offspring. The method 1: when only the genotype data of parents and progeny were known, the values of LOD of candidate parents were gained by CERVUS 2.0, and then two parents with the maximum LOD values were directly considered as the candidate parents. The method 2: when the values of every candidate parent of offspring as method 1 were calculated, the one with the maximum value of LOD was considered to the first candidate parent. In the condition that the first candidate was treated as a known parent, the LOD values of candidate parents of offspring were recalculated by CERVUS 2.0. The second candidate parent of every offspring was finally gained through selecting the candidate parents with maximum value of LOD again. The results showed that the accuracy rate exceeded 95% by the method 2, which suggested that the method 2 was suitable for the parentage identification of different shell color lines of Japanese scallop. As the null alleles were observed at the two loci of all the microsatellite loci from family F1 and F2, and which would lead to mismatch of the offspring and parents, two kinds of genotype files including the null alleles existing ones (situation 1) and the null alleles lost ones (situation 2) were used for the parentage analysis. The results suggested that there was no significant difference in the success rate of paternity testing in two situations, which revealed that the analysis for the value on LOD of candidate parents gained by some microsatellite loci would reduce the error occurred in parentage determination on the different shell color lines of P. yessoensis. Based on these results, it was concluded that the technique of microsatellite marker was competent for the task for parentage analysis of different shell color lines of P. yessoensis.