Balanced reciprocal and Robertsonian translocations are the most common structural chromosomal abnormalities in humans. Generally, they are without consequence for the carrier, but for various degrees of oligoasthenoteratozoospermia in men. As these carriers can produce a significant percentage of gametes with an unbalanced combination of the parental rearrangement, there is a more or less significant risk, according to cases, of chromosomal imbalances for their offspring. Therefore, techniques were developed to study the meiotic segregation of these translocations in males. Direct investigation of human sperm chromosomes became possible by karyotyping spermatozoa after penetration of zona-free hamster oocytes and, more recently, using fluorescent in situ hybridization (FISH). This paper reviews the results obtained using these techniques in Robertsonian and reciprocal translocations. The studies on spermatozoa from translocation carriers help the comprehension of the mechanisms of the meiotic segregation. They should be integrated in the genetic exploration of the infertile men, in order to give them a personalized risk assessment of unbalanced spermatozoa, specially as a correlation was found recently between the percentage of abnormal spermatozoa and that of abnormal embryos.
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http://dx.doi.org/10.1111/j.1365-2605.2004.00490.x | DOI Listing |
Plant Physiol
December 2024
Arameiosis Lab, South-Central Minzu University, Wuhan 430074, China.
Heat interferes with multiple meiotic processes, leading to genome instability and sterility in flowering plants, including many crops. Despite its importance for food security, the mechanisms underlying heat tolerance of meiosis are poorly understood. In this study, we analyzed different meiotic processes in the Arabidopsis (Arabidopsis thaliana) accessions Columbia (Col) and Landsberg erecta (Ler), their F1 hybrids, and the F2 offspring under heat stress (37°C).
View Article and Find Full Text PDFMol Biol Cell
December 2024
Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai-400076, India.
Chromosome condensation plays a pivotal role during faithful chromosome segregation, hence, understanding the factors that drive condensation is crucial to get mechanistic insight into chromosome segregation. Previously, we showed that in budding yeast, the absence of the non-essential kinetochore proteins affects chromatin-condensin association in meiosis but not in mitosis. A differential organization of the kinetochores, that we and others observed earlier during mitosis and meiosis may contribute to the meiotic-specific role.
View Article and Find Full Text PDFInt J Mol Sci
November 2024
Instituto de Biología Funcional y Genómica, IBFG, CSIC-USAL, 37007 Salamanca, Spain.
The cell cycle, essential for growth, reproduction, and genetic stability, is regulated by a complex network of cyclins, Cyclin-Dependent Kinases (CDKs), phosphatases, and checkpoints that ensure accurate cell division. CDKs and phosphatases are crucial for controlling cell cycle progression, with CDKs promoting it and phosphatases counteracting their activity to maintain balance. The nucleolus, as a biomolecular condensate, plays a key regulatory role by serving as a hub for ribosome biogenesis and the sequestration and release of various cell cycle regulators.
View Article and Find Full Text PDFbioRxiv
December 2024
Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Spindles are essential for accurate chromosome segregation in all eukaryotic cells. This study presents a novel approach for isolating fresh mammalian spindles from mouse oocytes, establishing it as a valuable model system for a wide range of possible studies. Our method enables the investigation of the physical properties and migration force of meiotic spindles in oocytes.
View Article and Find Full Text PDFbioRxiv
December 2024
Department of Biology, Johns Hopkins University, Baltimore, MD, USA 21218.
Chromosome mis-segregation is common in human meiosis and mitosis, and the resulting aneuploidies are the leading cause of pregnancy loss. Preimplantation genetic testing for aneuploidy (PGT-A) seeks to prioritize chromosomally normal embryos for transfer based on genetic analysis of a biopsy of approximately five trophectoderm cells from blastocyst-stage fertilized (IVF) embryos. While modern PGT-A platforms classify these biopsies as aneuploid, euploid, or mosaic (possessing a mixture of normal and aneuploid cells), the underlying incidences of aneuploid, euploid, and mosaic embryos and the rates of meiotic and mitotic error that produced them remain largely unknown.
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