Barklis E, Lodish H F
Cell. 1983 Apr;32(4):1139-48. doi: 10.1016/0092-8674(83)90297-0.
Prespore and prestalk cells in Dictyostelium discoideum aggregates can be separated by density gradient centrifugation. Using poly(A+) RNA from the fractionated cells to probe a cDNA library of mRNAs from postaggregation cells, we were able to identify six cDNA clones representing RNAs enriched in prespore or prestalk cells. Remarkably, transcripts of six of seven cDNA clones, previously selected to encode mRNAs present in postaggregating cells but low or absent in growing cells, also are enriched in RNA from either prestalk or prespore cells. By hybridization of cDNA probes to nitrocellulose blots of formaldehyde RNA gels, these 13 mRNA species have been examined with respect to cell type specificity, temporal pattern of accumulation, and affect of disaggregation and cAMP on accumulation. Aggregation-stage mRNAs tend to fit into three different classes. All prespore mRNAs are similar in all aspects of their regulation, while prestalk mRNAs fall into two co-regulated classes. All mRNAs that are present at significant levels during growth and differentiation are found in both cell types at comparable levels. Our results indicate that there is coordinate control of expression of genes specific for the two principal cell types.
盘基网柄菌聚集体中的前孢子细胞和前柄细胞可通过密度梯度离心分离。利用分级分离细胞中的聚腺苷酸（poly(A+)）RNA探测聚集后细胞mRNA的cDNA文库，我们能够鉴定出六个代表在前孢子或前柄细胞中富集的RNA的cDNA克隆。值得注意的是，先前选择用于编码聚集后细胞中存在但生长细胞中低表达或不表达的mRNA的七个cDNA克隆中的六个转录本，在前柄或前孢子细胞的RNA中也有富集。通过将cDNA探针与甲醛RNA凝胶的硝酸纤维素印迹杂交，对这13种mRNA在细胞类型特异性、积累的时间模式以及解聚和环磷酸腺苷（cAMP）对积累的影响方面进行了检测。聚集期mRNA倾向于分为三种不同类型。所有前孢子mRNA在其调控的各个方面都相似，而前柄mRNA分为两个共同调控的类型。在生长和分化过程中大量存在的所有mRNA在两种细胞类型中的水平相当。我们的结果表明，对两种主要细胞类型特异性基因的表达存在协同控制。
