To understand plant evolution and diversification, information regarding chromosome number meiotic behavior is imperative. The present study was carried out to determine the count, behavior, pollen fertility, seed set of a medicinally important Peganum harmala. Two cytotypes, diploid tetraploid are growing in western Himalaya; cytotype (2n=2x=24) Kashmir Himalaya, (2n=4x=48) Trans Ladakh. Chrom...

In conjugation of Tetrahymena thermophila, the paroral zone, cortical cytoplasm in the vicinity of the cytostome, is the site where nuclear selection occurs; one of the four meiotic products is selected in this site prior to the production of gametic pronuclei. During inbreeding cross experiments, several sterile strains were obtained which showed aberrant nuclear behavior. Conjugants of these ...

The genus Brachiaria (Trin.) Griseb. has achieved considerable importance to cattle production systems, as a result of the good production and adaptation of a few cultivars to poor and acid soils of the Brazilian savannas. Many of its species and accessions are polyploid and apomictic, which limits direct hybridization. To assist the breeding program, cytogenetic characterization has been under...

Early stages of meiotic prophase are characterized by complex and dramatic chromosome dynamics. Chromosome behavior during this period is associated with several critical meiotic processes that take place at the molecular level, such as recombination and homologous chromosome recognition and pairing. Studies to characterize specific patterns of chromosome dynamics and to identify their exact ro...

objective(s): sertoli cells support in vivo germ cell production; but, its exact mechanism has not been well understood. the present study was designed to analyze the effect of sertoli cells in differentiation of mouse embryonic stem cells (mescs) to germ cells.   materials and methods: a fusion construct composed of a stra8 gene promoter and the coding region of enhanced green fluorescence pro...

A strong correlation between GC content and recombination rate is observed in many eukaryotes, which is thought to be due to conversion events linked to the repair of meiotic double-strand breaks. In several organisms, the length of conversion tracts has been shown to decrease exponentially with increasing distance from the sites of meiotic double-strand breaks. I show here that this behavior l...

Kinetochores are considered to be the key structures that physically connect spindle microtubules to the chromosomes and play an important role in chromosome segregation during mitosis. Due to different mechanisms of spindle assembly between centrosome-containing mitotic cells and acentrosomal meiotic oocytes, it is unclear how a meiotic spindle generates the poleward forces to drive two rounds...

The meiotic properties of paracentric inversion heterozygotes have been well studied in insects and plants, but not in mammalian species. In essence, a single meiotic recombination event within the inverted region results in the formation of a dicentric chromatid, which usually breaks or is stretched between the two daughter nuclei during the first meiotic anaphase. Here, we provide evidence th...

Molecular mechanisms that initiate meiosis have been studied in fungi and mammals, but little is known about the mechanisms directing the meiosis transition in other organisms. To elucidate meiosis initiation in plants, we characterized and cloned the ameiotic1 (am1) gene, which affects the transition to meiosis and progression through the early stages of meiotic prophase in maize. We demonstra...

We have examined the meiotic recombination characteristics of artificial chromosomes in Saccharomyces cereuisiae. Our experiments were carried out using minichromosome derivatives of yeast chromosome ZZZ and yeast artificial chromosomes composed primarily of bacteriophage X DNA. Tetrad analysis revealed that the artificial chromosomes exhibit very low levels of meiotic recombination. However, w...