Confocal Analysis of Nuclear Lamina Behavior during Male Meiosis and Spermatogenesis in <i>Drosophila melanogaster</i>

Lamin family proteins are structural components of a filamentous framework, the nuclear lamina (NL), underlying the inner membrane of nuclear envelope. The NL not only plays a role in nucleus mechanical support and nuclear shaping, but is also involved in many cellular processes including DNA replication, gene expression and chromatin positioning. Spermatogenesis is a very complex differentiation process in which each stage is characterized by nuclear architecture dramatic changes, from the early mitotic stage to the sperm differentiation final stage. Nevertheless, very few data are present in the literature on the NL behavior during this process. Here we show the first and complete description of NL behavior during meiosis and spermatogenesis in Drosophila melanogaster. By confocal imaging, we characterized the NL modifications from mitotic stages, through meiotic divisions to sperm differentiation with an anti-laminDm0 antibody against the major component of the Drosophila NL. We observed that continuous changes in the NL structure occurred in parallel with chromatin reorganization throughout the whole process and that meiotic divisions occurred in a closed context. Finally, we analyzed NL in solofuso meiotic mutant, where chromatin segregation is severely affected, and found the strict correlation between the presence of chromatin and that of NL.核纤层蛋白家族（Lamin family proteins）是构成丝状骨架结构——核纤层（nuclear lamina, NL）的结构组分，该骨架附着于核被膜的内膜下方。核纤层不仅在细胞核机械支撑与核形态塑造中发挥作用，还参与诸多细胞过程，包括DNA复制、基因表达与染色质定位。精子发生（Spermatogenesis）是极为复杂的分化过程，其各个阶段均伴随核架构的显著变化，从早期有丝分裂阶段直至最终的精子分化阶段。然而，目前文献中关于该过程中核纤层行为的相关数据极少。本研究首次完整阐述了黑腹果蝇（Drosophila melanogaster）减数分裂与精子发生过程中的核纤层行为。我们通过靶向识别果蝇核纤层主要组分的抗laminDm0抗体，借助共聚焦成像（confocal imaging）对核纤层的修饰变化进行了表征，涵盖从有丝分裂阶段、减数分裂直至精子分化的全过程。研究发现，核纤层结构的持续变化与整个过程中的染色质重塑同步发生，且减数分裂以封闭形式进行。最后，我们对solofuso减数分裂突变体中的核纤层进行了分析，该突变体的染色质分离过程受到严重影响，结果发现染色质的存在与核纤层的存在二者间存在严格的相关性。