Comparative genome analysis of parthenogenetic nematode

2016 Fiscal Year Final Research Report

• Project/Area Number: 25250025
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Genome biology
• Research Institution: National Institute of Genetics
• Principal Investigator: KOHARA Yuji 国立遺伝学研究所, 系統生物研究センター, 特任教授 (70135292)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: ゲノムアセンブリ / 線虫 / 単為生殖 / 進化 / 減数分裂 / ゲノム多様性

Outline of Final Research Achievements

Although sexual reproduction is prevailing among eukaryotes, the nematode Diploscapter coronatus, a close relative of the model C. elegans, reproduces parthenogenetically. Neither males nor sperm have been observed and some steps of meiosis are apparently skipped in this species. To uncover the genomic changes associated with parthenogenetic reproduction, we carried out a genome analysis and we found that nearly 90% of the 170 Mbp draft genome sequences constitute homologous pairs with a 5.7% heterozygosity on average, meaning that the 170 Mbp sequences correspond to the diploid genome. Fluorescent staining showed that the D. coronatus genome consists of two chromosomes (2n = 2). Although 59 % of the C. elegans genes were found in the genome, many genes including those involved in sex determination and meiosis were missing or very divergent. Among them the defect of meiotic kleisins (rec-8 and coh-3/4) may be related to parthenogenetic reproduction.

Free Research Field

ゲノム生物学