Perlman S M, Ford P J, Rosbash M M
Proc Natl Acad Sci U S A. 1977 Sep;74(9):3835-9. doi: 10.1073/pnas.74.9.3835.
Complementary DNA transcribed from adult Xenopus laevis globin mRNA was used to assay ovary RNA from Xenopus for the presence of globin sequences by RNA.cDNA hybridization. These sequences are present at approximately the same concentration as the majority of poly(A)-containing ovary sequences. The sequences are also found at approximately 200,000 copies per cell in poly(A)-containing RNA extracted from mature oocytes. To rule out contamination of the oocytes with somatic cells, two additional experiments were performed. First, RNA isolated from ovulated unfertilized eggs, which are devoid of somatic cells, was also shown to contain the globin sequences. Second, globin mRNA was isolated from Xenopus tadpoles. Adult globin mRNA is free of the tadpole sequence and no homology was detected between adult and tadpoles globin RNA. The ovary was shown to contain tadpole globin RNA at nearly the same concentration as the adult sequences. Thus, the results cannot be explained by contamination with erythroid cells which should contain only the adult sequence. The swimming tadpole, which possesses an active circulatory system, was also assayed for the tadpole and adult globin sequences. Whereas the adult sequences are present at approximately the same concentration as in the mature oocyte, the concentration of the tadpole sequences increases at least 300-fold in the first 3 days following fertilization.
从成年非洲爪蟾珠蛋白mRNA转录而来的互补DNA，被用于通过RNA - cDNA杂交检测非洲爪蟾卵巢RNA中珠蛋白序列的存在情况。这些序列的浓度与大多数含poly(A)的卵巢序列大致相同。在从成熟卵母细胞中提取的含poly(A)的RNA中，这些序列的拷贝数约为每个细胞200,000个。为了排除卵母细胞被体细胞污染的可能性，又进行了另外两个实验。首先，从排卵后未受精的卵中分离出的RNA（这些卵不含体细胞）也被证明含有珠蛋白序列。其次，从非洲爪蟾蝌蚪中分离出珠蛋白mRNA。成年珠蛋白mRNA不含蝌蚪序列，并且在成年和蝌蚪的珠蛋白RNA之间未检测到同源性。结果表明，卵巢中蝌蚪珠蛋白RNA的浓度与成年序列的浓度几乎相同。因此，结果不能用仅应含有成年序列的红细胞污染来解释。对具有活跃循环系统的游动蝌蚪也进行了蝌蚪和成年珠蛋白序列的检测。成年序列的浓度与成熟卵母细胞中的大致相同，而蝌蚪序列的浓度在受精后的前3天至少增加了300倍。
