Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, Cidade Universitária, São Paulo 05508-090, Brazil.
Cells. 2020 Nov 5;9(11):2425. doi: 10.3390/cells9112425.
Dipterans exhibit a remarkable diversity of chromosome end structures in contrast to the conserved system defined by telomerase and short repeats. Within dipteran families, structure of chromosome termini is usually conserved within genera. With the aim to assess whether or not the evolutionary distance between genera implies chromosome end diversification, this report exploits two representatives of Sciaridae, , and .
Probes and plasmid microlibraries obtained by chromosome end microdissection, in situ hybridization, cloning, and sequencing are among the methodological approaches employed in this work.
The data argue for the existence of either specific terminal DNA sequences for each chromosome tip in , or sequences common to all chromosome ends but their extension does not allow detection by in situ hybridization. Both sciarid species share terminal sequences that are significantly underrepresented in chromosome ends of .
The data suggest an unusual terminal structure in chromosomes compared to other dipterans investigated. A putative, evolutionary process of repetitive DNA expansion that acted differentially to shape chromosome ends of the two flies is also discussed.
与端粒酶和短重复序列定义的保守系统相比，双翅目昆虫的染色体末端结构表现出显著的多样性。在双翅目科内，通常在属内保守染色体末端的结构。本报告旨在评估属间的进化距离是否暗示染色体末端多样化，为此利用了两个石蚕科的代表种， 和 。
本工作中采用的方法包括染色体末端显微切割、原位杂交、克隆和测序获得的探针和质粒微文库。
数据表明， 中的每条染色体末端都存在特定的末端 DNA 序列，或者存在所有染色体末端共有的序列，但它们的延伸无法通过原位杂交检测到。两种石蚕都共享在 染色体末端显著减少的末端序列。
与其他研究的双翅目昆虫相比， 的染色体末端结构异常。还讨论了一种可能的、重复 DNA 扩展的进化过程，该过程以不同的方式影响了两种苍蝇的染色体末端形成。
