Alvarenga Elenice M, Imperador Carlos H L, Bardella Vanessa B, Rodrigues Vera L C C, Mondin Mateus, Cabral-de-Mello Diogo C, Moraes Alberto S, Mello Maria Luiza S
Department of Structural and Functional Biology, Institute of Biology, University of Campinas (Unicamp), 13083-862 Campinas, SP, Brazil.
Department of Biology, Institute of Biosciences, State University of São Paulo (Unesp), 13506-900 Rio Claro, SP, Brazil.
Acta Histochem. 2018 Aug;120(6):572-577. doi: 10.1016/j.acthis.2018.07.002. Epub 2018 Jul 10.
Panstrongylus megistus, a potential vector of Chagas disease, currently occupies a wider geographic distribution in Brazil than Triatoma infestans, another member of the hemipteran Reduviidae family and a vector of the same disease. A small heterochromatic body (chromocenter) formed by the Y chromosome is evident in the somatic cells of P. megistus, differing in size and chromosome type contribution from the well-studied chromocenters present in T. infestans. While the overall distribution of histone epigenetic marks differ when comparing the heterochromatin and euchromatin territories in T. infestans, no similar data have been established for other hemipteran reduviids, including P. megistus. In the present work, histone acetylation and methylation marks were investigated in cells of Malpighian tubules of P. megistus 5th instar nymphs using immunocytochemical assays and compared to previously published data for T. infestans. Although similarities between these species were found regarding absence of acetylated H3K9, H4K8 and H4K16, and H3K9me and H3K9me in the chromocenter, presence of these marks in euchromatin, and presence of H3K9me in the chromocenter, no intimate association of acetylated H4K8 and 18S rDNA was revealed in the chromocenter of P. megistus. The elevated abundance of H3K9me marks at the nuclear periphery in P. megistus cells, differing from data for T. infestans, is suggested to reflect differences in the interaction of lamina-associated chromatin domains with the nuclear lamina, methyl-transferase modulation and/or association with the last DNA endoreplication step in 5th instar nymphs, which is a matter for further investigation.
大劣按蚊是恰加斯病的潜在传播媒介，目前在巴西的地理分布范围比锥蝽更广，锥蝽是半翅目猎蝽科的另一个成员，也是同一种疾病的传播媒介。由Y染色体形成的一个小的异染色质体（染色中心）在大劣按蚊的体细胞中很明显，其大小和染色体类型贡献与锥蝽中研究充分的染色中心不同。虽然在比较锥蝽的异染色质和常染色质区域时，组蛋白表观遗传标记的总体分布有所不同，但对于包括大劣按蚊在内的其他半翅目猎蝽科昆虫，尚未建立类似的数据。在本研究中，使用免疫细胞化学分析方法，对大劣按蚊五龄若虫马氏管细胞中的组蛋白乙酰化和甲基化标记进行了研究，并与之前发表的锥蝽数据进行了比较。尽管在这些物种之间发现了一些相似之处，如在染色中心不存在乙酰化的H3K9、H4K8和H4K16，以及H3K9me和H3K9me，在常染色质中存在这些标记，且在染色中心存在H3K9me，但在大劣按蚊的染色中心未发现乙酰化的H4K8与18S rDNA有紧密关联。大劣按蚊细胞中核周边H3K9me标记丰度升高，与锥蝽的数据不同，这表明可能反映了核纤层相关染色质结构域与核纤层的相互作用、甲基转移酶调节和/或与五龄若虫最后一次DNA内复制步骤的关联存在差异，这有待进一步研究。
