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，人口普查显示其数量约为350只。我正在测试一个假设，即该物种的低繁殖成功率是由于主要组织相容性复合体（MHC）位点的遗传多样性低。我们有来自390个个体的550个样本的DNA图谱（35个微卫星位点，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对母子，其中90头小牛被指定为父亲。对169个样本的MHC dr ß-样基因外显子2变异进行了初步调查，通过SSCP分析、克隆和测序鉴定出10个等位基因。每个个体中最多存在4个等位基因，表明有一个重复位点。通过遵循已知家族群体的遗传模式，6个等位基因被分配到一个位点（DRß-1），其余4个等位基因被分配到第二个位点（DRß-2）。单倍型被分配到28个信息丰富的雄性，具有指定的父系，并确定了父亲对小牛的贡献。我们测试了一个假设，即MHC单倍型更像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，这使得它不像它的母亲，在8个案例中，单倍型使它更像它的母亲。这种传递偏倚是非常显著的，而来自中性微卫星位点的等位基因的传递基本上是孟德尔式的。这个建议是在MHC中描述更多的I类和II类位点，并开发单倍型，以增加信息丰富的父亲的数量。我们目前有62名父亲没有提供信息，并且正在分析最近实地季节的另外100个样本，这应该会使父亲的数量至少增加20个。我们将描述引物已经在其他鲸鱼物种中开发的MHC位点，并针对同源位点，如人类HLA-G位点，直接参与怀孕期间的免疫耐受。我们还将研究交配群体中的MHC基因型，以评估交配是否像物种的混杂精子竞争假说所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.