Walawski Krzysztof, Czarnik Urszula, Wojciechowski Robert, Pareek Chandra S
Department of Animal Genetics, University of Warmia and Mazury in Olsztyn, ul. M. Oczapowskiego 5, 10-824 Olsztyn, Poland.
J Appl Genet. 2003;44(3):375-8.
The study was conducted on full-families of Black-and-White cattle obtained as 25 AI sire families and 355 cows, as well as their progenies, mostly heifers at the age of 1-3 months. The sire group was composed by the casual qualification of 10 PRNP 6/6 and 15 PRNP 6/5 individuals on the basis of accessible young progenies. The randomly selected group of cows is characterised by a very high frequency of PRNP 6/6 (74.9%), followed by lower frequency of PRNP 6/5 (24.5%) and a very low frequency of PRNP 5/5 genotype (0.6%). The progenies represent all expected genotypes, such as: PRNP 6/6 (60.5%), PRNP 6/5 (35.8%) and PRNP 5/5 (3.7%), respectively. Taking into consideration the genotypes of parents and progenies, the segregation of PRNP 6 and PRNP 5 alleles was analysed. Results of the non-informative mating variant of male symbol PRNP 6/6 x female symbol PRNP 6/6 (n = 87) are affected by the PRNP 6/6 progeny genotype in all cases. Subsequently, the results of mating variants male symbol PRNP 6/6 x female symbol PRNP 6/5 (n = 29) and male symbol PRNP 6/5 female symbol PRNP 6/6 (n = 179) showed statistically non-significant differences in both above-mentioned alternations. The progeny group related from male symbol PRNP 6/5 x female symbol PRNP 6/5 parental mating obtained fully informative and most valuable results based on the presented research concept. In the common group of 58 calves, the genotype PRNP 6/6 is represented by 26 individuals (44.8%), PRNP 6/5 - by 19 individuals (32.8%) and PRNP 5/5 - by 13 individuals (22.4%). Therefore, the theoretical genotype rate (25% : 50% : 25%) is drastically deformed and the differentiation between the observed and expected numbers of animals is statistically highly significant (chi(2) = 12.72; 2 df.). These differences are affected by two times higher PRNP 6/6 homozygous (chi(2) = 9.12; 1 df.) and responsively by the low number of PRNP 6/5 heterozygous animals (chi(2) = 3.45; 1 df.). Further investigations are carried out to explain the genetic determination of abnormal PRNP octa-peptide repeat allele segregation, which suggests possible lethal cis-trans linkage effects.
该研究以黑白花奶牛的全家族为对象，这些家族由25个人工授精父系家族和355头母牛及其后代组成，后代大多为1 - 3月龄的小母牛。父系组是根据可获取的年轻后代，随机挑选10头PRNP 6/6和15头PRNP 6/5个体组成。随机挑选的母牛组的特点是PRNP 6/6频率非常高（74.9%），其次是PRNP 6/5频率较低（24.5%），PRNP 5/5基因型频率极低（0.6%）。后代呈现出所有预期的基因型，分别为：PRNP 6/6（60.5%）、PRNP 6/5（35.8%）和PRNP 5/5（3.7%）。考虑到亲本和后代的基因型，分析了PRNP 6和PRNP 5等位基因的分离情况。雄性符号PRNP 6/6×雌性符号PRNP 6/6（n = 87）的非信息性交配变体结果在所有情况下均受PRNP 6/6后代基因型影响。随后，雄性符号PRNP 6/6×雌性符号PRNP 6/5（n = 29）和雄性符号PRNP 6/5×雌性符号PRNP 6/6（n = 179）的交配变体结果在上述两种交配中显示出统计学上无显著差异。基于所提出的研究概念，来自雄性符号PRNP 6/5×雌性符号PRNP 6/5亲本交配的后代组获得了完全信息且最有价值的结果。在58头小牛的共同组中，基因型PRNP 6/6由26头个体（44.8%）代表，PRNP 6/5由19头个体（32.8%）代表，PRNP 5/5由13头个体（22.4%）代表。因此，理论基因型比率（25% : 50% : 25%）严重变形，观察到的动物数量与预期数量之间的差异在统计学上高度显著（卡方 = 12.72；自由度为2）。这些差异受PRNP 6/6纯合子数量高出两倍（卡方 = 9.12；自由度为1）的影响，相应地受PRNP 6/5杂合动物数量较少（卡方 = 3.45；自由度为1）的影响。正在进行进一步研究以解释PRNP八肽重复等位基因异常分离的遗传决定因素，这表明可能存在致死性顺反连锁效应。
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