Reversion from Roughest to Wild Type in Drosophila Melanogaster.
Reversion from Roughest to Wild Type in Drosophila Melanogaster.
复制标题
黑腹果蝇从粗糙型向野生型的逆转。
作者：
B. Kaufmann
OUGHEST是黑腹果蝇的一种伴性隐性性状，表现为凸出、粗糙的眼睛，其小面大小和形状不规则。等位基因roughest 3（mi 3）由GRUNEBERG（1935）从X射线实验中获得。rst 3果蝇的眼睛显示出平滑和粗糙的镶嵌面，雄性的粗糙斑块比雌性的更明显。如果果蝇在16至19°C的温度下饲养，粗糙度会加重;在较高的温度下，雌性果蝇在外观上更经常与野生型重叠。两性的生存能力和生育能力都很好。遗传分析（GRUNE-BERG 1935）表明，rst 3与X染色体中的长倒位（In（~）rst~）相关，从最粗糙的基因座延伸到基因bobbed的右侧。由P. CH. KOLLER进行的初步细胞学研究（在GRUNEBERG 1935中报告）表明，存在于倒位杂合子果蝇的唾液腺染色体中的环从小面和红宝石位点之间的一点延伸到X染色体的近端异染色质区。EMMENS（1937）对唾液腺染色体的分析表明，倒位的左侧断裂位于3C 2至3C 4区域。该实验室的研究证实了埃蒙斯的解释;左折沿带3C 3（布里奇斯1938年的地图），反演延伸到约20 B分区。因此，3C 4带与最粗糙的基因座相关（由DEMEREC和SLIZYNSKA 1937证实），在遗传图谱上位于1.7（GRUNEBERG 1937，来自rst 2的分析，其表现为等位基因）。
OUGHEST is a sex-linked, recessive character of Drosophila melano- gaster manifested phenotypically in bulging, roughened eyes that have facets irregular in size and shape. The allele roughest3 (mi3) was obtained by GRUNEBERG (1935) from an X-ray experiment. Eyes of rst3 flies show mosaics of smooth and rough facets with rough patches more pronounced in the males than in the females. Roughness is accentuated if flies are raised at temperatures between 16 and 19°C; at higher temperatures the females more frequently overlap the wild type in appearance. Viability and fertility are good in both sexes. Genetic analysis (GRUNE-BERG 1935) indicated that rst3 is associated with a long inversion in the X chromosome (In(~)rst~), extending from the roughest locus to the right of the gene bobbed. Preliminary cytological studies by P. CH. KOLLER (reported in GRUNEBERG 1935) showed that the loop present in the salivary gland chromosomes of flies heterozygous for the inversion extends from a point between the loci of facet and ruby to the proximal heterochromatic region of the X. Subsequent analysis of salivary gland chromosomes by EMMENS (1937) disclosed that the left break of the inversion is in the 3C2 to 3C4 region. Studies made in this laboratory have confirmed EMMENS’S interpretation; the left break follows band 3C3 (BRIDGES’S 1938 map) and the inversion extends to about subdivision 20B. It does not include the nucleolus-organizing region, can be seen best in prophases of dividing neuroblasts The 3C4 band is thus associated with the roughest locus (confirmed by DEMEREC and SLIZYNSKA 1937), which on the genetic map is placed at 1.7 (GRUNEBERG 1937, from an analysis of rst2, which behaves as an allele).