Weintraub H, Beug H, Groudine M, Graf T
Cell. 1982 Apr;28(4):931-40. doi: 10.1016/0092-8674(82)90072-1.
Chicken bone marrow cells infected in vitro with a temperature-sensitive avian erythroblastosis virus fall to produce hemoglobin at 36 degrees C. When the product or products of the transforming gene (erb) are inactivated by a temperature shift to 42 degrees C in culture, several different cloned lines of cells infected with the temperature-sensitive avian erythroblastosis virus begin to make hemoglobin. This shift in phenotype correlates with an increase in hemoglobin mRNA specific to both adult and embryonic alpha and beta globin. The switch is accompanied by the acquisition of DNAase I-hypersensitive sites in one cell line (clone 2); however, a hypothetically more mature line (clone 3) has already acquired globin DNAase-hypersensitive sites but does not express hemoglobin until the temperature shift. Several (but not all) specific restriction sites associated with both the alpha and beta domains become unmethylated after the switch from 36 degrees C to 42 degrees C. The magnitude of these methylation switches is small compared with changes that occur in these genes during normal avian erythropoiesis. The results suggest that changes in chromosomal structure precede transcription and are not a consequence of transcription. Since (presumptive) precursor cloned lines can be established with some, but not all, of the structural properties of active globin chromatin, it is likely that many of these properties can be independently established and are not obligatorily related.
体外感染温度敏感型禽成红细胞增多症病毒的鸡骨髓细胞在36℃时无法产生血红蛋白。当培养物中的温度转变为42℃使转化基因（erb）的一个或多个产物失活时，感染了温度敏感型禽成红细胞增多症病毒的几个不同克隆细胞系开始合成血红蛋白。这种表型转变与成年和胚胎α及β珠蛋白特异的血红蛋白mRNA增加相关。这种转变伴随着一个细胞系（克隆2）中出现对DNA酶I敏感的位点；然而，一个假设中更成熟的细胞系（克隆3）已经具有珠蛋白对DNA酶敏感的位点，但直到温度转变才表达血红蛋白。从36℃转变到42℃后，与α和β结构域相关的几个（但不是全部）特定限制性位点变得去甲基化。与正常禽类红细胞生成过程中这些基因发生的变化相比，这些甲基化转变的幅度较小。结果表明，染色体结构的变化先于转录，而不是转录的结果。由于可以建立具有活性珠蛋白染色质部分（但不是全部）结构特性的（推测的）前体细胞克隆系，很可能这些特性中的许多可以独立建立，并非必然相关。
