Ueda K, Kinoshita Y, Xu Z J, Ide N, Ono M, Akahori Y, Tanaka I, Inoue M
Biotechnology Institute, Akita Prefectural University, Ohgata, Japan.
Chromosoma. 2000 Mar;108(8):491-500. doi: 10.1007/s004120050401.
We have cloned three novel histone genes using antibodies that recognize only nuclei of the male gametic (generative and sperm) cells of Lilium longiflorum. The deduced amino acid sequence of each clone shows only between 40% and 50% identity with the H2A, H2B and H3 somatic core histones of other plant species. Transcripts of these genes were first detected in bicellular pollen soon after microspore mitosis, and their mRNAs, as revealed by in situ hybridization, were observed only in the cytoplasm of the generative cells. As expression of these three genes was specific to generative cells within the bicellular pollen, we designated the clones gH2A, gH2B and gH3. Immunocytochemistry further revealed that the proteins encoded by these genes accumulated in the elongating and condensing generative nucleus during development of bicellular pollen, and were most abundant in the two sperm nuclei within an elongated pollen tube. We therefore propose that these male gamete-specific core histones contribute to chromatin condensation of male gametes or to chromatin remodeling, and result in the repression of gene expression in male gametes.
我们利用仅识别麝香百合雄配子（生殖细胞和精细胞）细胞核的抗体，克隆了三个新的组蛋白基因。每个克隆推导的氨基酸序列与其他植物物种的H2A、H2B和H3体细胞核心组蛋白的同一性仅在40%至50%之间。这些基因的转录本在小孢子有丝分裂后不久首次在二细胞花粉中被检测到，原位杂交显示它们的mRNA仅在生殖细胞的细胞质中被观察到。由于这三个基因的表达在二细胞花粉内特定于生殖细胞，我们将这些克隆命名为gH2A、gH2B和gH3。免疫细胞化学进一步揭示，这些基因编码的蛋白质在二细胞花粉发育过程中在伸长和浓缩的生殖细胞核中积累，并在伸长的花粉管内的两个精核中含量最高。因此，我们认为这些雄配子特异性核心组蛋白有助于雄配子的染色质浓缩或染色质重塑，并导致雄配子中基因表达的抑制。
