STUDIES ON METATHERIAN SEX-CHROMOSOMES .2. IMPROBABILITY OF A STABLE BALANCED POLYMORPHISM AT AN X-LINKED LOCUS WITH PATERNAL X INACTIVATION SYSTEM OF KANGAROOS
STUDIES ON METATHERIAN SEX-CHROMOSOMES .2. IMPROBABILITY OF A STABLE BALANCED POLYMORPHISM AT AN X-LINKED LOCUS WITH PATERNAL X INACTIVATION SYSTEM OF KANGAROOS
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DOI：
10.1071/bi9760245
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发表时间：
1976-01-01
期刊：
影响因子：
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通讯作者：
COOPER, DW
中科院分区：
文献类型：
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作者：
COOPER, DW
雌性袋鼠和其他雌性有袋动物对其体细胞中的 X 连锁基因具有独特的剂量补偿形式。在这些动物中，父系 X 不活跃。因此，杂合子女性具有一种或另一种纯合子的表型，其表达的等位基因来自其母亲。然而，未表达的父系衍生等位基因可以以通常的孟德尔方式传递给下一代并在那里表达。袋鼠 X 连锁基因的单倍体表型表达和二倍体基因型行为的这种组合使得它们的群体遗传学独一无二。检查了袋鼠 X 染色体系统中平衡选择的可能性，平衡多态性不太可能发生。如果1-a、1、1-b和1分别是α1雌性、α2雌性、α1雄性和α2雄性的选择系数(其中α1是A1表达时的表型，α2是A2表达时的表型)，则当雌性中A1的基因频率＝0.5时达到平衡(a-1 + b-1)，仅对 a 和 b 的少数生物学可能值取 0 到 1 之间的值。
Female kangaroos and perhaps other female marsupials have a unique form of dosage compensation for X-linked genes in their soma. In these animals the paternal X is inactive. Heterozygote females therefore have the phenotype of one or the other of the homozygotes, with the allele which is expressed coming from their mother. The unexpressed paternally derived allele may, however, be transmitted to the next generation in the usual Mendelian manner and there be expressed. Such a combination of haploid phenotypic expression and diploid genotypic behavior on the part of X-linked genes in kangaroos makes their population genetics unique. The possibilities for balancing selection in the kangaroo X chromosome system is examined and balanced polymorphisms are unlikely to occur. If 1-a, 1, 1-b, and 1 are the selection coefficients of the .alpha.1 females, .alpha.2 females, .alpha.1 males and .alpha.2 males, respectively (where .alpha.1 is the phenotype when A1 is expressed and .alpha.2 the phenotype when A2 is expressed), then the equilibrium is reached when the gene frequency of A1 in females = 0.5 (a-1 + b-1), which takes values between 0 and 1 for only a few of the biologically likely values of a and b.