The major histocompatibility complex and right whale reproduction

北大西洋露脊鲸是世界上最濒危的鲸鱼之一，人口普查数量约为350头。我正在验证一个假设，即物种的低繁殖成功率是由于主要组织相容性复合体(MHC)基因座的低遗传多样性所致。我们有代表390个个体的550个样本的DNA图谱(35个微卫星座位、线粒体DNA控制区序列和性别-Zfx/ZfY)。这代表了大约70%的物种，包括150对母牛，其中90对小牛已被指定为父亲。用SSCP分析、克隆和测序的方法，对169份样本进行了MHC DR？样基因外显子2变异的初步调查，共鉴定出10个等位基因。在每个个体中存在多达四个等位基因，表明存在重复的基因座。根据已知家系的遗传模式，将6个等位基因分配给一个座位(DR？1)，将其余4个等位基因分配给第二个座位(DR？2)。单倍型被分配给28个信息丰富的雄性，分配给父亲，并确定父亲对小牛的贡献。我们测试了一种假设，即MHC单倍型更像他们的母亲的胎儿更有可能被终止妊娠。在20个案例中，小牛接受了父亲的MHC单倍型，这使它不太像它的母亲，而在8个案例中，单倍型使它更像它的母亲。这种传递偏差是非常显著的，而来自中性微卫星座位的等位基因的传递基本上是孟德尔式的。这项建议是为了描述更多MHC中的I类和II类基因座，并开发单倍型来增加信息丰富的父亲的数量。我们目前有62个没有提供信息的父亲，正在对最近野外季节的另外100个样本进行分析，这些样本应该会使父子关系至少增加20个。我们将描述在其他鲸鱼物种中已经开发出的MHC基因座，以及目标同源基因座，例如直接与怀孕期间的免疫耐受有关的人类人类白细胞抗原-G基因座。我们还将观察交配群体中的MHC基因类型，以评估交配是否像从该物种的精子竞争混杂假说中预测的那样是随机的。

The North Atlantic right whale is one of the most endangered whales in the world, with a census population of about 350 individuals. I am testing the hypothesis that the low reproductive success of the species is due to the low genetic diversity at Major Histocompatibility Complex (MHC) loci. We have DNA profiles (35 microsatellite loci, the mitochondrial DNA control region sequence and gender - ZfX/ZfY) from 550 samples representing 390 individuals. This represents approximately 70% of the species and includes 150 mother calf pairs, of which 90 calves have been assigned paternity. A preliminary survey of exon 2 variation of the MHC DRß-like gene with 169 samples identified 10 alleles using SSCP analysis, cloning and sequencing. Up to four alleles were present in each individual indicating a duplicated locus. By following inheritance patterns of known family groupings, six alleles were assigned to one locus (DRß-1) and remaining four alleles were assigned to the second locus (DRß-2). Haplotypes were assigned to 28 informative males with assigned paternities and the paternal contribution to the calf determined. We tested the hypothesis that fetuses with MHC haplotypes more like their mother would be more likely to be terminated. In twenty cases the calf received the paternal MHC haplotype that made it less like its mother and in 8 cases the haplotype that made it more like its mother. This transmission bias is highly significant, while the transmission of alleles from the neutral microsatellite loci was essentially Mendelian. This proposal is to characterise more class I and II loci in the MHC and develop haplotypes to increase the number of informative fathers. We presently have 62 fathers that are not informative and are profiling another 100 samples from the recent field seasons that should increase the paternities by at least 20. We will characterise MHC loci for which primers have been developed in other whale species and target homologous loci such as the human HLA-G locus that is directly involved immune tolerance during pregnancy. We will also look at MHC genotypes in mating groups to assess whether mating is random as predicted from the promiscuous sperm competition hypothesis for the species.