Detterbeck S, Morandini P, Wetterauer B, Bachmair A, Fischer K, MacWilliams H K
Zoologisches Institut, Ludwig-Maximilians-Universität, München, Germany.
Development. 1994 Oct;120(10):2847-55. doi: 10.1242/dev.120.10.2847.
In transgenic strains of Dictyostelium discoideum that express beta-galactosidase under the control of a prespore-specific promoter, only early slugs show reporter confined to the prespore zone. As slugs migrate beta-galactosidase-positive cells accumulate in the prestalk zone; ultimately, there may be so many that the prestalk-prespore boundary is no longer distinguishable (Harwood, A., Early, A., Jermyn, K. and Williams, J. (1991) Differentiation 46, 7-13). It is not clear whether these 'anomalous' reporter-positive cells currently express prespore genes; another possibility is that they are ex-prespore cells that have transformed to prestalk and sorted to the prestalk zone (Sternfeld, J. (1993) Roux Archiv. Dev. Biol. 201, 354-363), while retaining their previously produced reporter. To test the activity of the prespore genes in these cells, we have made prespore reporter constructs whose products decay quickly; these are based on constructs used to investigate protein turnover in yeast (Bachmair, A., Finley, D. and Varshavsky, A. (1986) Science 234, 179-186). In strains bearing such constructs, beta-galactosidase-positive cells do not appear in the prestalk zone. The apparent deterioration of the prestalk/prespore pattern in older slugs is thus an artefact of reporter stability.
在盘基网柄菌的转基因菌株中，β-半乳糖苷酶在孢子前体特异性启动子的控制下表达，只有早期蛞蝓显示报告基因局限于孢子前体区域。随着蛞蝓迁移，β-半乳糖苷酶阳性细胞在前柄区域积累；最终，可能会有如此多的阳性细胞以至于前柄-孢子前体边界不再可区分（哈伍德，A.，厄尔利，A.，杰明，K.和威廉姆斯，J.（1991年）《分化》46卷，第7 - 13页）。目前尚不清楚这些“异常”的报告基因阳性细胞是否表达孢子前体基因；另一种可能性是它们是已转变为前柄细胞并分选到前柄区域的前孢子细胞（施特恩费尔德，J.（1993年）《鲁克斯发育生物学文献》201卷，第354 - 363页），同时保留它们之前产生的报告基因。为了测试这些细胞中孢子前体基因的活性，我们构建了孢子前体报告基因构建体，其产物快速降解；这些构建体基于用于研究酵母中蛋白质周转的构建体（巴赫迈尔，A.，芬利，D.和瓦尔沙夫斯基，A.（1986年）《科学》234卷，第179 - 186页）。在携带此类构建体的菌株中，β-半乳糖苷酶阳性细胞不会出现在前柄区域。因此，较老蛞蝓中前柄/孢子前体模式的明显恶化是报告基因稳定性的一种假象。
