2 DISCRETE MODES OF HISTONE GENE-EXPRESSION DURING OOGENESIS IN DROSOPHILA-MELANOGASTER
2 DISCRETE MODES OF HISTONE GENE-EXPRESSION DURING OOGENESIS IN DROSOPHILA-MELANOGASTER
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DOI：
10.1016/0012-1606(85)90447-6
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发表时间：
1985-01-01
影响因子：
2.7
通讯作者：
SCHEDL, P
中科院分区：
文献类型：
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作者：
AMBROSIO, L;SCHEDL, P
我们使用卵巢组织切片的原位杂交来研究果蝇卵子发生过程中组蛋白基因的表达模式。我们的研究表明，卵子发生过程中组蛋白基因表达有两个不同的阶段。第一阶段发生在卵子发生早期到中期（阶段 5-10A），我们在卵室的 15 个护理细胞中观察到组蛋白 mRNA 的镶嵌模式：一些细胞具有非常高水平的 mRNA，而另一些细胞则具有很少或没有 mRNA。我们的分析表明，卵室中组蛋白 mRNA 存在周期性积累和随后的降解，并且很少有组蛋白 mRNA 被转运到生长中的卵母细胞中。此外，由于在此期间护士细胞的内有丝分裂复制周期是异步的，组蛋白信息的镶嵌分布表明每个护士细胞核中组蛋白基因的表达可能与大多数体细胞中的DNA复制耦合。第二阶段从阶段 10B 开始。在此期间，组蛋白基因表达似乎在卵室的所有 15 个护理细胞中被“诱导”，并且在所有细胞中都发现高水平的组蛋白 mRNA，而不是马赛克模式。与早期阶段不同，这种表达显然与护士细胞的内有丝分裂复制（在阶段 10A 结束时完成）脱钩。此外，许多新合成的组蛋白 mRNA 从护士细胞转运到卵母细胞中，在那里积累并储存以供早期胚胎发生期间使用。最后，我们还在非变性组织切片中观察到滋养细胞核内紧密聚集的颗粒。与细胞质组蛋白 mRNA 的情况一样，从第 5 阶段到第 10A 阶段，核颗粒呈镶嵌分布，而在第 10B 阶段，几乎所有滋养细胞核都具有颗粒簇。这些颗粒簇似乎是由于护士细胞组蛋白基因 DNA 与我们的探针杂交所致，并且位于细胞核的特定区域。
We have used in situ hybridization to ovarian tissue sections to study the pattern of histone gene expression during oogenesis in Drosophila melanogaster. Our studies suggest that there are two distinct phases of histone gene expression during oogenesis. In the first phase, which occurs during early to middle oogenesis (stages 5-10A), we observe a mosaic pattern of histone mRNA in the 15 nurse cells of the egg chamber: some cells have very high levels of mRNA, while others have little or no mRNA. Our analysis suggests that there is a cyclic accumulation and subsequent degradation of histone mRNA in the egg chamber and that very little histone mRNA is transported into the growing oocyte. Moreover, since the endomitotic replication cycles of the nurse cells are asynchronous during this period, the mosaic distribution of histone message would suggest that the expression of the histone genes in each nurse cell nucleus is probably coupled to DNA replication as in most somatic cells. The second phase begins at stage 10B. During this period, histone gene expression appears to be "induced" in all 15 nurse cells of the egg chamber, and instead of a mosaic pattern, high levels of histone mRNA are found in all cells. Unlike the earlier phase, this expression is apparently uncoupled from the endomitotic replication of the nurse cells (which are completed by the end of stage 10A). Moreover, much of the newly synthesized histone mRNA is transported from the nurse cells into the oocyte where it accumulates and is stored for use during early embryogenesis. Finally, we have also observed tightly clustered grains within nurse cell nuclei in non-denatured tissue sections. As was the case with cytoplasmic histone mRNA, there is a mosaic distribution of nuclear grains from stages 5 to 10A, while at stage 10B, virtually all nurse cell nuclei have grain clusters. These grain clusters appear to be due to the hybridization of nurse cell histone gene DNA to our probe, and are localized in specific regions of the nucleus.