{"title":"苍蝇 Bradysia(Sciara)的非随机染色体分离和染色体淘汰。","authors":"Susan A Gerbi","doi":"10.1007/s10577-022-09701-9","DOIUrl":null,"url":null,"abstract":"<p><p>Mendelian inheritance is based upon random segregation of homologous chromosomes during meiosis and perfect duplication and division of chromosomes in mitosis so that the entire genomic content is passed down to the daughter cells. The unusual chromosome mechanics of the fly Bradysia (previously called Sciara) presents many exceptions to the canonical processes. In male meiosis I, there is a monopolar spindle and non-random segregation such that all the paternal homologs move away from the single pole and are eliminated. In male meiosis II, there is a bipolar spindle and segregation of the sister chromatids except for the X dyad that undergoes non-disjunction. The daughter cell that is nullo-X degenerates, whereas the sperm has two copies of the X. Fertilization restores the diploid state, but there are three copies of the X chromosome, of which one or two of the paternally derived X chromosomes will be eliminated in an early cleavage division. Bradysia (Sciara) coprophila also has germ line limited L chromosomes that are eliminated from the soma. Current information and the molecular mechanisms for chromosome imprinting and eliminations, which are just beginning to be studied, will be reviewed here.</p>","PeriodicalId":50698,"journal":{"name":"Chromosome Research","volume":null,"pages":null},"PeriodicalIF":2.4000,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10777868/pdf/","citationCount":"3","resultStr":"{\"title\":\"Non-random chromosome segregation and chromosome eliminations in the fly Bradysia (Sciara).\",\"authors\":\"Susan A Gerbi\",\"doi\":\"10.1007/s10577-022-09701-9\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Mendelian inheritance is based upon random segregation of homologous chromosomes during meiosis and perfect duplication and division of chromosomes in mitosis so that the entire genomic content is passed down to the daughter cells. The unusual chromosome mechanics of the fly Bradysia (previously called Sciara) presents many exceptions to the canonical processes. In male meiosis I, there is a monopolar spindle and non-random segregation such that all the paternal homologs move away from the single pole and are eliminated. In male meiosis II, there is a bipolar spindle and segregation of the sister chromatids except for the X dyad that undergoes non-disjunction. The daughter cell that is nullo-X degenerates, whereas the sperm has two copies of the X. Fertilization restores the diploid state, but there are three copies of the X chromosome, of which one or two of the paternally derived X chromosomes will be eliminated in an early cleavage division. Bradysia (Sciara) coprophila also has germ line limited L chromosomes that are eliminated from the soma. Current information and the molecular mechanisms for chromosome imprinting and eliminations, which are just beginning to be studied, will be reviewed here.</p>\",\"PeriodicalId\":50698,\"journal\":{\"name\":\"Chromosome Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.4000,\"publicationDate\":\"2022-09-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10777868/pdf/\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Chromosome Research\",\"FirstCategoryId\":\"99\",\"ListUrlMain\":\"https://doi.org/10.1007/s10577-022-09701-9\",\"RegionNum\":4,\"RegionCategory\":\"生物学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2022/7/6 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q3\",\"JCRName\":\"BIOCHEMISTRY & MOLECULAR BIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chromosome Research","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1007/s10577-022-09701-9","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2022/7/6 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 3
摘要
孟德尔遗传的基础是同源染色体在减数分裂过程中的随机分离,以及染色体在有丝分裂过程中的完美复制和分裂,从而使整个基因组内容传递给子细胞。苍蝇 Bradysia(以前称为 Sciara)的染色体机械结构不同寻常,它的典型过程有许多例外。在雄性减数分裂 I 中,存在单极纺锤体和非随机分离,所有父系同源染色体都远离单极并被淘汰。在雄性减数分裂 II 中,出现双极纺锤体和姐妹染色单体的分离,但 X 染色体不发生分离。受精后会恢复二倍体状态,但 X 染色体有三个拷贝,其中一个或两个父源 X 染色体会在早期裂殖分裂中被消除。Bradysia (Sciara) coprophila 也具有种系限制的 L 染色体,这些染色体会从体细胞中消除。本文将对染色体印记和消除的现有信息和分子机制进行综述,这些研究刚刚起步。
Non-random chromosome segregation and chromosome eliminations in the fly Bradysia (Sciara).
Mendelian inheritance is based upon random segregation of homologous chromosomes during meiosis and perfect duplication and division of chromosomes in mitosis so that the entire genomic content is passed down to the daughter cells. The unusual chromosome mechanics of the fly Bradysia (previously called Sciara) presents many exceptions to the canonical processes. In male meiosis I, there is a monopolar spindle and non-random segregation such that all the paternal homologs move away from the single pole and are eliminated. In male meiosis II, there is a bipolar spindle and segregation of the sister chromatids except for the X dyad that undergoes non-disjunction. The daughter cell that is nullo-X degenerates, whereas the sperm has two copies of the X. Fertilization restores the diploid state, but there are three copies of the X chromosome, of which one or two of the paternally derived X chromosomes will be eliminated in an early cleavage division. Bradysia (Sciara) coprophila also has germ line limited L chromosomes that are eliminated from the soma. Current information and the molecular mechanisms for chromosome imprinting and eliminations, which are just beginning to be studied, will be reviewed here.
期刊介绍:
Chromosome Research publishes manuscripts from work based on all organisms and encourages submissions in the following areas including, but not limited, to:
· Chromosomes and their linkage to diseases;
· Chromosome organization within the nucleus;
· Chromatin biology (transcription, non-coding RNA, etc);
· Chromosome structure, function and mechanics;
· Chromosome and DNA repair;
· Epigenetic chromosomal functions (centromeres, telomeres, replication, imprinting,
dosage compensation, sex determination, chromosome remodeling);
· Architectural/epigenomic organization of the genome;
· Functional annotation of the genome;
· Functional and comparative genomics in plants and animals;
· Karyology studies that help resolve difficult taxonomic problems or that provide
clues to fundamental mechanisms of genome and karyotype evolution in plants and animals;
· Mitosis and Meiosis;
· Cancer cytogenomics.