Barclay S L, Henderson E J
Proc Natl Acad Sci U S A. 1982 Jan;79(2):505-9. doi: 10.1073/pnas.79.2.505.
A thermosensitive developmental mutant of Dictyostelium discoideum identifies a gene product that is nonessential for cell multiplication but is continuously required during aggregation and the period when multicellular mounds are formed. After mounds form a tip, which has the properties of an embryonic organizer, this gene product may be nonessential. Surgical removal of the tip from a polarized developing multicellular structure (the slug) leads to emergence of a new tip at the permissive temperature but not at the restrictive temperature. The mutant continues to develop abnormally when mixed with wild-type cells; therefore, a cell-limited rather than an exchangeable factor is altered. Assays show that the mutant has a thermosensitive defect in chemotaxis toward cAMP. The mutation reduces the number of cell surface cAMP receptors expressed at the restrictive temperature without affecting their dissociation constants or their apparent thermostability. The expression of two developmentally regulated enzymes, N-acetylglucosaminidase and cAMP phosphodiesterase, is unaffected by the mutation.
盘基网柄菌的一个热敏发育突变体鉴定出一种基因产物，该产物对细胞增殖并非必需，但在聚集以及形成多细胞丘的时期持续需要。在丘形成具有胚胎组织者特性的尖端后，这种基因产物可能不再必需。从极化发育的多细胞结构（蛞蝓体）中手术移除尖端，在允许温度下会导致新尖端出现，而在限制温度下则不会。该突变体与野生型细胞混合时会继续异常发育；因此，是一种细胞受限而非可交换因子发生了改变。检测表明，该突变体在对环磷酸腺苷（cAMP）的趋化性方面存在热敏缺陷。该突变在限制温度下减少了细胞表面cAMP受体的数量，而不影响其解离常数或表观热稳定性。两种受发育调控的酶，N - 乙酰葡糖胺酶和cAMP磷酸二酯酶的表达不受该突变影响。
