Angelier N, Penrad-Mobayed M, Billoud B, Bonnanfant-Jaïs M L, Coumailleau P
Laboratoire de Biologie Moléculaire et Cellulaire du Développement, Université Pierre et Marie Curie, Paris, France.
Int J Dev Biol. 1996 Aug;40(4):645-52.
The biological significance of lampbrush chromosomes from urodelan amphibians is far from being elucidated. Their particularly well developed lateral loops are the site of intense transcriptional activity, which can be visualized in electron microscopy using the Miller spreading procedure. All transcription units functioning in lampbrush loops synthesize RNA at a maximum rate. In situ hybridization has provided evidence for transcription of both unique coding sequences and highly repetitive sequences. The role of lampbrush transcripts in the production of maternal information remains unclear. RNAs transcribed from unique coding sequences are exported to the cytoplasm; there, they contribute either to maintaining the required level of maternal messenger RNA in a basal state during late oogenesis, or to increasing the store of these maternal RNAs throughout oocyte growth, i.e., until stage VI. For repetitive sequences, their intense transcription appears to be non-productive, in that RNAs are not translatable and might be useless products of readthrough transcription. The non-productive transcription of repetitive sequences, the expression of which is directly related to hyperdevelopment of lateral loops, raises the issue of the role of lampbrush chromosome transcription.
有尾两栖动物灯刷染色体的生物学意义远未阐明。它们特别发达的侧环是强烈转录活动的场所，使用米勒铺展法在电子显微镜下可以观察到这种活动。在灯刷环中发挥作用的所有转录单位都以最大速率合成RNA。原位杂交为独特编码序列和高度重复序列的转录提供了证据。灯刷转录本在母体信息产生中的作用仍不清楚。从独特编码序列转录的RNA被输出到细胞质中；在那里，它们要么有助于在卵母细胞发生后期维持基础状态下所需的母体信使RNA水平，要么在整个卵母细胞生长过程中，即直到VI期，增加这些母体RNA的储备。对于重复序列，它们的强烈转录似乎是无效的，因为RNA不可翻译，可能是通读转录的无用产物。重复序列的无效转录与侧环的过度发育直接相关，这就引发了灯刷染色体转录作用的问题。
