Visa N, Gonzàlez-Duarte R, Santa-Cruz M C
Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Spain.
Chromosoma. 1988;97(2):171-7. doi: 10.1007/BF00327375.
Analysis of puffing patterns in Drosophila melanogaster salivary gland chromosomes indicates the existence of a developmentally specific puff in the 35B region. This puff seems to originate from bands 35B2 or 35B3, where Adh is located, and it is expanded in more than 60% of the nuclei examined. The presence of RNA polymerase II in this puff as well as its ability to incorporate tritiated uridine shows that it corresponds to a transcriptionally active site. RNA blotting and in situ hybridization experiments indicate that Adh is transcribed, although not very actively, in salivary glands during the third larval instar. However, this tissue does not display detectable levels of ADH activity. By contrast, we have found that in midgut polytene chromosomes the 35B region is not visibly puffed in spite of the high levels of Adh transcripts detected. These results seem to suggest that puffing at the 35B region could be mainly promoted by genes closely linked to Adh, possibly with a minor contribution of this gene.
对黑腹果蝇唾液腺染色体中胀泡模式的分析表明，在35B区域存在一种发育特异性胀泡。这种胀泡似乎起源于Adh所在的35B2或35B3带，并且在所检查的超过60%的细胞核中会扩展。该胀泡中存在RNA聚合酶II以及其掺入氚化尿苷的能力表明它对应于一个转录活性位点。RNA印迹和原位杂交实验表明，在第三龄幼虫期，Adh在唾液腺中被转录，尽管转录活性不是很高。然而，该组织未显示出可检测到的ADH活性水平。相比之下，我们发现，尽管检测到高水平的Adh转录本，但在中肠多线染色体中，35B区域并未明显胀泡。这些结果似乎表明，35B区域的胀泡可能主要由与Adh紧密连锁的基因促进，该基因可能起次要作用。
