Samollow P B, Johnston P G, Ford A L, VandeBerg J L
Department of Biology, Lehigh University, Bethlehem, Pennsylvania 18015-3189.
Biochem Genet. 1989 Jun;27(5-6):313-20. doi: 10.1007/BF00554166.
Fibroblasts cultured from ear pinna biopsies of Virginia opossums (Didelphis virginiana) and red-necked wallabies (Macropus rufogriseus) were examined electrophoretically to determine the relative expression levels of the maternally and paternally derived alleles at X-linked, enzyme-coding loci. Only the maternally derived allele was expressed at the Pgk-A locus in fibroblasts of heterozygous D. virginiana (M. rufogriseus not examined), but fibroblasts of both species exhibited evidence of paternal allele expression at the Gpd locus. Furthermore, the heterozygous G6PD phenotypes in both species were skewed in favor of the maternal gene product, as expected if the paternal allele is only partially (incompletely) expressed. For M. rufogriseus this result is contrary to a previous finding which suggested equal expression of both Gpd alleles in cultured fibroblasts of this species. The present results suggest that X-linked genes in metatherian fibroblasts are subject to the same kind of determinate, paternal allele inactivation, incomplete at some loci, described previously for X-linked genes in adult tissues and that the pattern of paternal X-linked gene expression in these cells is independent of the patterns in the tissues from which the fibroblasts are derived.
对从弗吉尼亚负鼠（Didelphis virginiana）和红颈小袋鼠（Macropus rufogriseus）耳廓活检组织培养的成纤维细胞进行了电泳分析，以确定X连锁的酶编码基因座上母源和父源等位基因的相对表达水平。在杂合的弗吉尼亚负鼠（未检测红颈小袋鼠）的成纤维细胞中，仅母源等位基因在磷酸甘油酸激酶A（Pgk-A）基因座表达，但两个物种的成纤维细胞在葡萄糖-6-磷酸脱氢酶（Gpd）基因座均表现出父源等位基因表达的证据。此外，两个物种的杂合葡萄糖-6-磷酸脱氢酶（G6PD）表型均偏向母源基因产物，这与父源等位基因仅部分（不完全）表达时的预期一致。对于红颈小袋鼠而言，这一结果与之前的一项发现相反，该发现表明该物种培养的成纤维细胞中两个Gpd等位基因表达相等。目前的结果表明，有袋类动物成纤维细胞中的X连锁基因会经历与之前在成年组织中描述的X连锁基因相同类型的决定性父源等位基因失活，在某些基因座不完全失活，并且这些细胞中父源X连锁基因的表达模式与成纤维细胞来源组织中的模式无关。
