Lee J J, Calzone F J, Britten R J, Angerer R C, Davidson E H
J Mol Biol. 1986 Mar 20;188(2):173-83. doi: 10.1016/0022-2836(86)90302-5.
The number of molecules of mRNA transcribed from each of five different actin genes are reported for developing embryos of the sea urchin Strongylocentrotus purpuratus. Transcripts of the cytoskeletal actin genes CyI, CyIIa, CyIIb and CyIIIa, and of the muscle actin gene M, were measured in unfertilized egg and embryo RNAs of cleavage, blastula, gastrula and pluteus stages. The measurements were obtained by probe excess titrations of these RNAs, using a set of single-stranded RNA probes each identifying the mRNA transcripts of a specific actin gene. These mRNAs can be identified by their distinct 3' non-translated trailer sequences. We confirm prior observations that the prevalence of actin mRNA in the unfertilized egg is low. Cytoskeletal actin genes CyI and CyIIIa each contribute 1 X 10(3) to 2 X 10(3) maternal mRNA molecules, and CyIIb contributes less than 2 X 10(2) mRNA molecules, while no detectable maternal mRNAs derive from cytoskeletal actin gene CyIIa or the muscle actin gene M. During certain periods of development, transcripts derived from the individual cytoskeletal actin genes accumulate rapidly, with kinetics specific to each mRNA. Transcripts of the muscle actin gene are absent until after gastrulation, when the initial muscle progenitor cells are formed. At late stages of development, each of the five genes studied is represented by 10(4) to 10(5) mRNA molecules per embryo. The present measurements permit calculation of the levels of each actin mRNA species in the particular cell types in which each gene functions in the fully differentiated embryo.
对于紫海胆强壮柱头虫发育中的胚胎，报告了从五个不同肌动蛋白基因转录的mRNA分子数量。在未受精卵以及卵裂期、囊胚期、原肠胚期和幼体期胚胎的RNA中，测量了细胞骨架肌动蛋白基因CyI、CyIIa、CyIIb和CyIIIa以及肌肉肌动蛋白基因M的转录本。这些测量是通过对这些RNA进行探针过量滴定获得的，使用一组单链RNA探针，每个探针识别特定肌动蛋白基因的mRNA转录本。这些mRNA可通过其独特的3'非翻译尾序列来识别。我们证实了之前的观察结果，即未受精卵中肌动蛋白mRNA的丰度较低。细胞骨架肌动蛋白基因CyI和CyIIIa各自贡献1×10³至2×10³个母体mRNA分子，而CyIIb贡献少于2×10²个mRNA分子，而未检测到来自细胞骨架肌动蛋白基因CyIIa或肌肉肌动蛋白基因M的母体mRNA。在发育的某些阶段，来自各个细胞骨架肌动蛋白基因的转录本迅速积累，每个mRNA具有特定的动力学。直到原肠胚形成初始肌肉祖细胞后，肌肉肌动蛋白基因的转录本才出现。在发育后期，每个研究的五个基因在每个胚胎中由10⁴至10⁵个mRNA分子代表。目前的测量结果允许计算在完全分化的胚胎中每个基因发挥功能的特定细胞类型中每种肌动蛋白mRNA的水平。
