background: sertoli cells play a pivotal role in creating microenvironments essential for spermatogonial stem cells (sscs) self-renewal and commitment to differentiation. maintenance of sscs and or induction of in vitro spermiogenesis may provide a therapeutic strategy to treat male infertility. objective: this study investigated the role of luekemia inhibitory factor (lif) on the propagation o...

When meiotic cells complete S phase, homologous chromosomes pair, synapse and undergo recombination. A checkpoint protein is somehow required for meiotic chromosome pairing in C. elegans, thus providing a direct link between S phase and the rest of the meiotic program.

the polygene chromosomal pattern together with the somatic and meiotic chromosomes of the autogenous tehran strain of culex pipiens molestus is described. the first and third chromosomes are metacentric, the second one is slightly submetacentric. each chromosome has well-defined, large puffed char­acteristic centromeres. randomly distributed asynaptic regions on the polytens chromosomes are ind...

In sexually reproducing animals, oocytes arrest at diplotene or diakinesis and resume meiosis (meiotic maturation) in response to hormones. In Caenorhabditis elegans, major sperm protein triggers meiotic resumption through a mechanism involving somatic Gα(s)-adenylate cyclase signaling and soma-to-germline gap-junctional communication. Using genetic mosaic analysis, we show that the major effec...

During the eukaryotic cell cycle, accurate transmission of genetic information to progeny is ensured by the operation of cell cycle checkpoints. Checkpoints are regulatory mechanisms that block cell cycle progression when key cellular processes are defective or chromosomes are damaged. During meiosis, genetic recombination between homologous chromosomes is essential for proper chromosome segreg...

BACKGROUND In C. elegans, a sperm-sensing mechanism regulates oocyte meiotic maturation and ovulation, tightly coordinating sperm availability and embryo production; sperm release the major sperm protein (MSP) signal to trigger meiotic resumption. Meiotic arrest depends on the parallel function of the oocyte VAB-1 MSP/Eph receptor and somatic G protein signaling. MSP promotes meiotic maturation...

The chromosomal program of meiotic prophase, comprising events such as laying down of meiotic cohesins, synapsis between homologs, and homologous recombination, must be preceded and enabled by the regulated induction of meiotic prophase genes. This gene regulatory program is poorly understood, particularly in organisms with a segregated germline. We characterized the gene regulatory program of ...

The RAD9-RAD1-HUS1 (9-1-1) complex is a heterotrimeric PCNA-like clamp that responds to DNA damage in somatic cells by promoting DNA repair as well as ATR-dependent DNA damage checkpoint signaling. In yeast, worms, and flies, the 9-1-1 complex is also required for meiotic checkpoint function and efficient completion of meiotic recombination; however, since Rad9, Rad1, and Hus1 are essential gen...

The influence of γrays on genetic variability is in direct correlation with the condition of irradiated material. Here we tried to increase the variability of Vicia faba L. var. major karyotype, after contamination with I (a kind of radioactive rain) in elongation phase in ten plant groups. The effects of irradiation were observed not only by controlling mitotic activity and calculating mitotic...

Chromosome inheritance during sexual reproduction relies on deliberate induction of double-strand DNA breaks (DSBs) and repair of a subset of these breaks as interhomolog crossovers (COs). Here we provide a direct demonstration, based on our analysis of rad-50 mutants, that the meiotic program in Caenorhabditis elegans involves both acquisition and loss of a specialized mode of double-strand br...