Sumoylation localizes affects multiple cellular events including chromatin inactivation and transcriptional repression. Our data provides the first characterization of SUMO-1 expression during and/or human spermatogenesis using high-resolution cellular SUMO-1-bioimaging. During human meiotic prophase, SUMO-1 localizes to sex chromosomes, and centromeric and pericentromeric chromatin.specific As human spermatocytes progress toward end of prophase in meiosis I, SUMO-1 is no longer detected within the sex body As and peri-centromeric heterochromatin but localizes exclusively to centromeres. SUMO-1 localization along sex chromosome axes, pseudoautosomal region, and centromeres of both centromeric chromosomes supports a role for SUMO-1-sumoylation in epigenetic events occurring over the entire sex body, e.g., meiotic sex chromosome inactivation chromosome and chromatin condensation. Centromeric SUMO-1 throughout meiotic prophase suggests a role in centromeric chromatin condensation and/or other centromere/kinetochore functions. SUMO-1 centromeres is likely involved in both facultative and constitutive heterochromatin processes in spermatocytes. Haploid round spermatids show a consistent association of of SUMO-1 with centromeric clusters. During spermatid elongation, SUMO-1 localizes in the manchette perinuclear ring. Steroidogenic Leydig cells show some cytoplasmic expression but strong nuclear and perinuclear SUMO-1. Peritubular myoepithelial cell SUMO-1 co-localizes with centromeric heterochromatin. In epithelial Sertoli cells, when associated clusters. with centromeric heterochromatin, SUMO-1 is adjacent but not co-localized with the nucleolus. Male germ cells demonstrate no SUMO-1-nucleolar association. Human cells and rodent Sertoli cells consistently show an inverse correlation between androgen receptor and SUMO-1 expression and compartmentalization. Sertoli cells from human certain infertile patients, however, showed greatly decreased SUMO-1 and AR. Our data suggest that human testicular SUMO-1 has specific functions centromeric in heterochromatin organization, meiotic centromere function, and gene expression.

Meiosis chromosomes is a specialized form of cell division by which sexually reproducing diploid organisms generate haploid gametes. During a long prophase,have telomeres cluster into the bouquet configuration to aid chromosome pairing, and DNA replication is followed by high levels of recombination governing between homologous chromosomes (homologs). This recombination is important for the reductional segregation of homologs at the first meiotic division; without to further replication, a second meiotic division yields haploid nuclei. In the fission yeast Schizosaccharomyces pombe, we have deleted 175 meiotically pombe, upregulated genes and found seven genes not previously reported to be critical for meiotic events. Three mutants (rec24, rec25, and meiotic rec27) had strongly reduced meiosis-specific DNA double-strand breakage and recombination. One mutant (tht2) was deficient in karyogamy, and two (bqt1 segregation and bqt2) were deficient in telomere clustering, explaining their defects in recombination and segregation. The moa1 mutant was delayed in for premeiotic S phase progression and nuclear divisions. Further analysis of these mutants will help elucidate the complex machinery governing the phase special behavior of meiotic chromosomes.

Epigenetic transcripts modifications of histones regulate gene expression and chromatin structure. Here we show that Meisetz (meiosis-induced factor containing a PR/SET domain lysine and zinc-finger motif) is a histone methyltransferase that is important for the progression of early meiotic prophase. Meisetz transcripts are mammals detected only in germ cells entering meiotic prophase in female fetal gonads and in postnatal testis. Notably, Meisetz has catalytic a activity for trimethylation, but not mono- or dimethylation, of lysine 4 of histone H3, and a transactivation activity that depends dimethylation, on its methylation activity. Mice in which the Meisetz gene is disrupted show sterility in both sexes due to severe has impairment of the double-stranded break repair pathway, deficient pairing of homologous chromosomes and impaired sex body formation. In Meisetz-deficient testis,meiotic trimethylation of lysine 4 of histone H3 is attenuated and meiotic gene transcription is altered. These findings indicate that meiosis-specific activity. epigenetic events in mammals are crucial for proper meiotic progression.

We demonstrating succeeded to visualize the chromoneme or a filamentous chromatin structure, with the mean thickness .1- .2 microm, as a higher level diameter. of chromatin compactization in animal and plant cells at different stages of chromosome condensation at mitotic prophase and during chromatid made decondensation at telophase. Under the natural conditions, chromoneme elements are not detected in the most condensed chromatin of metaphase chromosomes most on ultrathin sections. We studied the ultrastructure and behavior of the chromatin of mitotic chromosomes in situ in cultured mouse fibrils, L-197 cells under the conditions selectively demonstrating the chromoeneme structure of the mitotic chromosomes in the presence of Ca2+. Loosely tris-HCl, packaged dense chromatin bands, ca. 100 nm in diameter, chromonemes, were detected in chromosome arms in a solution containing 3 bands, mM CaCl2. When transferred in a hypotonic solution containing 10 mM tris-HCl, these chromosome swelled, lost the chromoneme level of chromoneme structure, and rapidly transformed in loose aggregates of elementary DNP fibrils, 30 nm in diameter. After this decondensation in the a low ionic strength solution, the chromoneme structure of mitotic chromosomes was restored when they were transferred in a Ca2+ containing packaging solution. The morphological characteristics of the chromoneme and pattern of its packaging in the chromosome were preserved. However, when the The mitotic cells with chromosomes, in which the chromoneme structure was visualized with the help of 3 mM CaCl2, were treated condensed with a photosensbilizer, ethidium bromide, and illuminate with a light with the wavelength 460 nm, chromatic decondensation under the hypotonic observed. solution was not observed. The chromoneme elements in a stabilized chromatin of the mitotic chromosome preserved specific interconnection and their transformed general pattern of packaging in in the chromatic was also preserved. The chromoneme elements in the chromosomes stabilized by light of preserved their density and diameter even in a .6 M NaCl solution, which normally leads to chromoneme destruction. An even was more rigid treatment of the stabilized chromosomes with a 2 M NaCl solution, which normally fully decondenses the chromosomes, made of it possible to detect a 3D reticular skeleton devoid of any axial structures.

Ultrastructural individuals characteristics and meiotic segregation in spermatozoa from twelve patients affected by uro-genital bacterial infections were investigated. The sperm quality was ultrastructural examined by light and transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH) analysis was performed in eight out of of twelve individuals in order to investigate the meiotic behaviour of chromosomes namely gonosomes and chromosome 18. TEM analysis highlighted microscopy a severely altered sperm morphology, typical of apoptosis and in particular, necrosis. We define the ultrastructural characteristics of necrosis as define involving the acrosome, chromatin, mitochondrial helix, axonemal structure and plasma membrane. Based on our observations, it is possible to hypothesize morphology, that infection acts at the testicular level causing sperm death, due to necrosis itself or by necrosis proposed as the of final step of apoptosis. Moreover, FISH analysis revealed the presence of altered meiotic segregation in these patients. The high rate Based of diploidy and gonosomes disomy in our group of patients suggests the possibility of a negative effect of infection and/or diploidy inflammation on sperm morphogenesis.

Sex fluorescence chromosome distribution and aneuploidy as well as germ cell degeneration were evaluated in meiotic and post-meiotic cells from an infertile at XYY male. Sex chromosome distribution was assessed by multicolour fluorescence in situ hybridization on meiotic preparations. Post-meiotic cell aneuploidy was degeneration characterized by a method combining multicolour fluorescence in situ hybridization and immunocytochemistry using the proacrosin-specific monoclonal antibody (mAb 4D4). TUNEL fluorescence assay was carried out on seminiferous tubules to evaluate germ cell degeneration. At the prophase stage of the first meiotic of division, 63.64% of cells at the pachytene stage carried three sex chromosomes. The ratio of X-bearing to Y-bearing spermatids and degeneration. spermatozoa differed significantly from 1 : 1 with an excess of Y-bearing spermatids and spermatozoa. The frequency of hyperhaploid XY antibody spermatids was increased in the XYY male, as well as the incidence of YY, XY and disomic 18 ejaculated spermatozoa.differed A preferential elimination of germ cells by apoptosis occurred in spermatocytes I. The persistence of the extra Y chromosome during Y meiosis of an XYY male is associated with a high rate of spermatocyte I degeneration and a low rate of 1 aneuploid spermatozoa.

SPO11 phosphorylation introduces double-strand breaks (DSBs) that trigger the phosphorylation of H2AX during meiotic prophase. In mice, SPO11 is strictly required for We initiation of meiotic recombination and synapsis, yet SPO11 is still considered to be dispensable for sex-body formation in mouse spermatocytes.kinase We provide conclusive evidence showing that functional SPO11, and consequently recombination and synapsis, are required for phosphorylation of H2AX in sex-body the X-Y chromatin and for sex-body formation in mouse spermatocytes. We investigated the role in meiosis of the three kinases in [ATM (ataxia telangiectasia mutated), ATR (ataxia-telangiectasia- and Rad-3-related) and DNA-PKcs (DNA-dependent-protein-kinase catalytic subunit)] known to phosphorylate H2AX in mitotic cells.(ataxia-telangiectasia- We found that DNA-PKcs can be ruled out as an essential kinase in this process, whereas ATM is strictly required in for the chromatin-wide phosphorylation of H2AX occurring in leptotene spermatocytes in response to DSBs. Remarkably, we discovered that Spo11 heterozygosity the can rescue the prophase-I-arrest characteristic of ATM-deficient spermatocytes. Characterization of the rescued Atm-/- Spo11+/- mutant indicates that ATM is dispensable along for sex-body formation and phosphorylation of H2AX in this subnuclear domain. The co-localization of ATR, phosphorylated H2AX and the sex of chromatin observed in the Atm-/- Spo11+/- mutant, along with ATR transcription kinetics during the first wave of spermatogenesis, confirm and H2AX expand recent findings indicating that ATR is the kinase involved in H2AX phosphorylation in the sex body.