Adler P N, Charlton J, Park W J
Biology Department, University of Virginia, Charlottesville 22903.
Genetics. 1994 Jul;137(3):829-36. doi: 10.1093/genetics/137.3.829.
The adult cuticular wing of Drosophila is covered with an array of distally pointing hairs. Mutations in the inturned (in) gene result in both abnormal hair polarity (i.e., hairs no longer point distally), and, in most cells forming more than one hair. We have isolated and characterized a collection of in alleles. Among this collection of alleles are a number of rearrangements that enable us to assign in to 77B3-5. Almost all of the in alleles, including putative null alleles, result in a stronger phenotype on the wing at 18 degrees than 29 degrees. The data argue that the in-dependent process is cold-sensitive. Temperature shift experiments with a hypomorphic allele show that this cold sensitivity can be relieved by several hours of incubation at the permissive temperature at a variety of times in the early pupae, but that this ability ends prior to the start of hair morphogenesis. One new allele showed a dramatic heat sensitivity. Temperature shift experiments with this allele revealed a very short temperature-sensitive period that is a few hours prior to the start of hair morphogenesis. That the temperature during hair morphogenesis is irrelevant for the phenotype of in is consistent with the hypothesis that the only role that in has in wing hair development is to regulate the initiation of hair morphogenesis.
果蝇成虫的表皮翅膀上覆盖着一系列指向远端的刚毛。内翻（in）基因的突变会导致刚毛极性异常（即刚毛不再指向远端），并且在大多数形成不止一根刚毛的细胞中也会出现这种情况。我们分离并鉴定了一系列in等位基因。在这些等位基因中，有许多重排使我们能够将in定位到77B3 - 5。几乎所有的in等位基因，包括假定的无效等位基因，在18摄氏度时翅膀上的表型比在29摄氏度时更强。数据表明in依赖的过程对温度敏感。用一个亚效等位基因进行的温度转换实验表明，在早期蛹期的不同时间，在允许温度下孵育几个小时可以缓解这种冷敏感性，但这种能力在刚毛形态发生开始之前就结束了。一个新的等位基因表现出显著的热敏感性。用这个等位基因进行的温度转换实验揭示了一个非常短的温度敏感期，即在刚毛形态发生开始前几个小时。刚毛形态发生期间的温度与in的表型无关，这与in在翅膀刚毛发育中唯一的作用是调节刚毛形态发生的起始这一假设是一致的。
