Hummon Margaret Raper, Costello Walter J
Department of Zoological and Biomedical Sciences/College of Osteopathic Medicine, Ohio University, 45701, Athens, OH, USA.
Rouxs Arch Dev Biol. 1992 Apr;201(2):88-94. doi: 10.1007/BF00420419.
A blastoderm fate map has been prepared for Drosophila, using mosaics of a temperature-sensitive mutation, shibire (shi). The mutation can cause abnormal flight muscle morphology, inducible only by a short heat pulse in early metamorphosis. Thus muscle lineage and development are unperturbed until the heat pulse in the early pupa. The developmental focus of the shi muscle phenotype maps to the ventral thorax at the expected site of thoracic mesoderm, and probably indicates the blastoderm progenitors of the adult flight muscle. The fate map provides greater detail than previously available for the dorsolongitudinal fibers (DLM) of flight muscle, showing wide separation of the fibers of flight muscle. DLM fibers a and b map close together, and far anterior to fibers e and f, which also map together. On a fate map, common developmental focus indicates a common blastoderm origin. Thus, the observed pattern for DLM fibers suggests that the blastoderm progenitors for each of these syncytial fiber pairs (a, b; e, f) include only one or two cells. It follows that there is usually a single genotype within each fiber pair (a, b; e, f), and that this genotype is directly reflected in the fiber phenotype. In a large number of cases, DLM fibers a and b differ in phenotype from other DLM fibers, in parallel with their other differences (e.g., timing of development in pupa, innervation, motor activity). The separation of fate map locations of the developmental focus for DLM fibers within mesoderm suggests that specific fibers of flight muscle may, in normal development, originate in all three thoracic mesodermal parasegments.
利用温度敏感突变体“失活”（shi）的镶嵌体，已经绘制出了果蝇的胚盘命运图谱。该突变会导致飞行肌形态异常，仅在变态初期短时间热脉冲诱导下才会出现。因此，在蛹早期热脉冲之前，肌肉谱系和发育不受干扰。shi肌肉表型的发育焦点映射到胸腹中胚层预期位置的腹侧胸部，这可能表明了成年飞行肌的胚盘祖细胞。该命运图谱比以前可获得的飞行肌背纵纤维（DLM）的图谱提供了更详细的信息，显示出飞行肌纤维的广泛分离。DLM纤维a和b映射在一起，且远在纤维e和f的前方，纤维e和f也映射在一起。在命运图谱上，共同的发育焦点表明有共同的胚盘起源。因此，观察到的DLM纤维模式表明，这些合胞体纤维对（a，b；e，f）中每一对的胚盘祖细胞仅包括一两个细胞。由此可见，每个纤维对（a，b；e，f）内通常只有单一基因型，并且这种基因型直接反映在纤维表型中。在大量情况下，DLM纤维a和b在表型上与其他DLM纤维不同，这与它们的其他差异（例如蛹期发育时间、神经支配、运动活动）并行。中胚层内DLM纤维发育焦点的命运图谱位置分离表明，在正常发育中飞行肌的特定纤维可能起源于所有三个胸段中胚层副节。
