Kartout-Benmessaoud Yasmine, Ouchia-Benissad Siham, Mahiddine-Aoudjit Leila, Ladjali-Mohammedi Kafia
Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene (USTHB), Laboratory of Cellular and Molecular Biology, Team of Developmental Genetics. PO box 32 El-Alia, Bab-Ezzouar, 16110, Algiers, Algeria University of Sciences and Technology Houari Boumediene (USTHB) Algiers Algeria.
Faculty of Nature and Life Sciences, Department of Physico-Chemical Biology, University Abderrahmane Mira, Campus Targa Ouzemour, 06000, Bejaia, Algeria University Abderrahmane Mira Bejaia Algeria.
Comp Cytogenet. 2024 Dec 3;18:213-237. doi: 10.3897/compcytogen.18.135056. eCollection 2024.
Birds are one of the most diverse groups among terrestrial vertebrates. They evolved from theropod dinosaurs, are closely related to the sauropsid group and separated from crocodiles about 240 million years ago. According to the IUCN, 12% of bird populations are threatened with potential extinction. Classical cytogenetics remains a powerful tool for comparing bird genomes and plays a crucial role in the preservation populations of endangered species. It thus makes it possible to detect chromosomal abnormalities responsible for early embryonic mortalities. Thus, in this work, we have provided new information on part of the evolutionary history by analysing high-resolution GTG-banded chromosomes to detect inter- and intrachromosomal rearrangements in six species. Indeed, the first eight autosomal pairs and the sex chromosomes of the domestic fowl Linnaeus, 1758 were compared with five species, four of which represent the order Galliformes (Common and Japanese quail, Gambras and Chukar partridge) and one Otidiformes species (Houbara bustard). Our findings suggest a high degree of conservation of the analysed ancestral chromosomes of the four Galliformes species, with the exception of (double, terminal, para and pericentric) inversions, deletion and the formation of neocentromeres (1, 2, 4, 7, 8, Z and W chromosomes). In addition to the detected rearrangements, reorganisation of the Houbara bustard chromosomes mainly included fusions and fissions involving both macro- and microchromosomes (especially on 2, 4 and Z chromosomes). We also found interchromosomal rearrangements involving shared microchromosomes (10, 11, 13, 14 and 19) between the two analysed avian orders. These rearrangements confirm that the structure of avian karyotypes will be more conserved at the interchromosomal but not at intrachromosomal scale. The appearance ofa small number of inter- and intrachromosomal rearrangements that occurred during evolution suggests a high degree of conservatism of genome organisation in these six species studied. A summary diagram of the rearrangements detected in this study is proposed to explain the chronology of the appearance of various evolutionary events starting from the ancestral karyotype.
鸟类是陆生脊椎动物中最多样化的群体之一。它们由兽脚亚目恐龙进化而来，与蜥形纲关系密切，约在2.4亿年前与鳄鱼分道扬镳。根据国际自然保护联盟（IUCN）的数据，12%的鸟类种群面临潜在灭绝的威胁。经典细胞遗传学仍然是比较鸟类基因组的有力工具，在濒危物种种群保护中发挥着关键作用。因此，它能够检测导致早期胚胎死亡的染色体异常。因此，在这项工作中，我们通过分析高分辨率GTG带型染色体来检测六个物种的染色体间和染色体内重排，从而提供了部分进化历史的新信息。的确，将家鸡（林奈，1758）的前八对常染色体和性染色体与五个物种进行了比较，其中四个代表鸡形目（普通鹌鹑和日本鹌鹑、蓝胸鹑和石鸡），一个鸨形目物种（细嘴鸨）。我们的研究结果表明，除了（双着丝粒、末端、臂间和着丝粒周围）倒位、缺失和新着丝粒的形成（1、2、4、7、8、Z和W染色体）外，四个鸡形目物种分析的祖先染色体具有高度保守性。除了检测到的重排外，细嘴鸨染色体的重组主要包括涉及大染色体和小染色体（特别是2、4和Z染色体）的融合和裂变。我们还发现了两个分析的鸟类目之间涉及共享小染色体（10、11、13、14和19）的染色体间重排。这些重排证实，鸟类核型结构在染色体间尺度上更保守，但在染色体内尺度上并非如此。进化过程中发生的少量染色体间和染色体内重排的出现表明，在所研究的这六个物种中基因组组织具有高度保守性。本文提出了本研究中检测到的重排的示意图，以解释从祖先核型开始的各种进化事件出现的时间顺序。
