The second minireview describes the importance of
meiotic recombination in meiosis, and the current
understanding of this process and its control mecha-nisms. Imperfections in meiotic recombination have
been linked withde novo germline mutations, abnor-mal gametes, and infertility.
Homologous recombination (HR) serves to eliminate deleterious
lesions, such as double-stranded breaks and interstrand crosslinks,
from chromosomes. HR is also critical for the preservation of replication
forks, for telomere maintenance, and chromosome segregation
in meiosis I. As such, HR is indispensable for the maintenance
of genome integrity and the avoidance of cancers in humans. The
HR reaction is mediated by a conserved class of enzymes termed
In meiosis, the accurate segregation of maternal and paternal chromosomes
is accomplished by homologous recombination. A central player in meiotic
recombination is the Dmc1 recombinase, a member of the RecA⁄Rad51
recombinase superfamily, which is widely conserved from viruses to
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Analysis of anther transcriptomes to identify genes contributing to meiosis and male gametophyte development in rice
Recombination of homologous chromosomes is essential for correct reduc-tional segregation of homologous chromosomes, which characterizes meio-sis. To accomplish homologous recombination, chromosomes must find
their homologous partners and pair with them within the spatial con-straints of the nucleus.
Sexual reproduction depends on the success of faithful chromosome trans-mission during meiosis to yield viable gametes. Central to meiosis is the
process of recombination between paternal and maternal chromosomes,
which boosts the genetic diversity of progeny and ensures normal homo-logous chromosome segregation.
Meiotic recombination is initiated by DNA double-stranded breaks intro-duced by the SPO11 protein. Despite a decade of research, the biochemical
functions of SPO11 remain largely unknown, perhaps because of difficulties
in studying the functionally active SPO11.
In this review, we describe the role of a small ubiquitin-like protein modi-fier (SUMO)-conjugating protein, Ubc9, in synaptonemal complex forma-tion during meiosis in a basidiomycete, Coprinus cinereus. Because its
meiotic cell cycle is long and naturally synchronous, it is suitable for
molecular biological, biochemical and genetic studies of meiotic prophase
Sumoylation is a post-translational modification system that covalently
attaches the small ubiquitin-related modifier (SUMO) to target proteins.
Ubc9 is required as the E2-type enzyme for SUMO-1 conjugation to tar-gets. Here, we show that Ubc9 interacts with the meiosis-specific RecA
homolog, Lim15⁄Dmc1 in the basidiomyceteCoprinus cinereus(CcLim15),
and mediates sumoylation of CcLim15 during meiosis.
In eukaryotes, meiosis leads to genetically variable gametes through recom-bination between homologous chromosomes of maternal and paternal ori-gin. Chromatin organization following meiotic recombination is critical to
ensure the correct segregation of homologous chromosomes into gametes.
However, the mechanism of chromatin organization after meiotic recombi-nation is unknown.
Previously, the activity of DNA polymeraseawas found in
the meiotic prophase I including non-S phase stages, in the
basidiomycetes,Coprinus cinereus. To study DNA poly-merasea during meiosis, we cloned cDNAs for the
C. cinereusDNApolymeraseacatalytic subunit (p140) and
C. cinereusprimase small subunit (p48). Northern analysis
indicated that both p140 and p48 are expressed not only
at S phase but also during the leptotene/zygotene stages of
meiotic prophase I.
In this chapter, students will be able to understand: Contrast haploid and diploid chromosome numbers, explain what is meant by homologous chromosomes, describe the role of crossing-over in contributing to genetic variation, define independent assortment and describe how it contributes to genetic variation in the offspring,...
This chapter include objectives: Evaluate the effects of continuous variation, pleiotropic genes, lack of complete dominance, environmental modifications of genes, and epistasis on disease; understand the importance of crossing over in terms of gene assortment and construction of genetic maps; describe the many genetic disorders discussed in the text, their symptoms, relative frequency in specialized populations, and their genetic basis;...
This chapter distinguish between the following terms: somatic cell and gamete, autosome and sex chromosomes, haploid and diploid; describe the events that characterize each phase of meiosis; describe three events that occur during meiosis I but not mitosis; name and explain the three events that contribute to genetic variation in sexually reproducing organisms.
(BQ) Part 1 book "High-Yield cell and molecular biology - Cell and molecular biology" presents the following contents: Chromosomal DNA, chromosome replication, meiosis and genetic recombination, the human nuclear genome, the human mitochondrial genome, protein synthesis, control of gene expression, mutations of the dna sequence.
Trong cơ thể đa bào, có 1 số tế bào có hoạt động phân chia cao như tế bào tuỷ xương, có tế bào phân chia thấp như tế bào gan và cũng có những tế bào hoàn toàn không phân chia như các nơron thần kinh. Các mô ung thư có hoạt tính phân bào cao. 11.2.3. Sự phân bào giảm nhiễm (meiosis) 126.96.36.199. Đặc điểm của phân bào giảm nhiễm Như ta đã biết, nhờ phân bào nguyên nhiễm mà có sự phân bố đồng đều NST về các tế bào con, và các tế bào con dù...