Carnegie Institution for Science, Baltimore, MD, USA.
Carnegie Institution for Science, Baltimore, MD, USA; Saint Petersburg State University, Saint Petersburg, Russia.
Exp Cell Res. 2021 Apr 15;401(2):112523. doi: 10.1016/j.yexcr.2021.112523. Epub 2021 Mar 3.
The lampbrush chromosomes (LBCs) in oocytes of the Mexican axolotl (Ambystoma mexicanum) were identified some time ago by their relative lengths and predicted centromeres, but they have never been associated completely with the mitotic karyotype, linkage maps or genome assembly. We identified 9 of the axolotl LBCs using RNAseq to identify actively transcribed genes and 13 BAC (bacterial artificial clone) probes containing pieces of active genes. Using read coverage analysis to find candidate centromere sequences, we developed a centromere probe that localizes to all 14 centromeres. Measurements of relative LBC arm lengths and polymerase III localization patterns enabled us to identify all LBCs. This study presents a relatively simple and reliable way to identify each axolotl LBC cytologically and to anchor chromosome-length sequences (from the axolotl genome assembly) to the physical LBCs by immunostaining and fluorescence in situ hybridization. Our data will facilitate a more detailed transcription analysis of individual LBC loops.
墨西哥蝾螈（Ambystoma mexicanum）卵母细胞中的灯刷染色体（LBCs）很久以前就因其相对长度和预测的着丝粒而被识别出来，但它们从未与有丝分裂核型、连锁图谱或基因组组装完全相关联。我们使用 RNAseq 鉴定了 9 个蝾螈 LBC，以鉴定活跃转录的基因，以及 13 个含有活性基因片段的 BAC（细菌人工克隆）探针。通过使用读取覆盖度分析来寻找候选着丝粒序列，我们开发了一个可以定位到所有 14 个着丝粒的着丝粒探针。相对 LBC 臂长的测量和聚合酶 III 定位模式使我们能够识别所有的 LBC。本研究提供了一种相对简单可靠的方法，可通过免疫染色和荧光原位杂交技术在细胞学上鉴定每个蝾螈 LBC，并将染色体长度序列（来自蝾螈基因组组装）锚定到物理 LBC 上。我们的数据将促进对单个 LBC 环的更详细转录分析。
