s:1993:"Background: There are many approaches that gene expression is controlled in eukaryotes. DNA methylation is one of several epigenetic mechanisms that cells use to control gene expression and lock genes in the "off" position. In addition, sperm DNA damage can correlate with DNA methylation defect. There is evidence that sperm of infertile men contain more DNA damage than fertile men and t...

Background: Alcohol abuse is considered as one of the problems associated with poor semen production and sperm quality. Both acute and chronic alcohol consumption may affect spermatozoal chromatin disorders through apoptosis. Therefore, for the first time, this experimental study was performed to evaluate the effect of ethanol consumption on sperm parameters and chromatin integrity of spermatoz...

introduction: to evaluate and compare efficiency of sil-select with percoll to recover sperm with normal chromatin in morphology and also studyeffect of these parameters on fertilization, embryo quality and cleavagescore. materials and methods: assessment of semen parameters, protamine deficiency (cma3) and excessive histone (aniline blue staining) were carried out before and after sperm proces...

Two populations of Astyanax altiparanae (Garutti & Britski, 2000) of the Água dos Patos stream/SP and lake Igapó/PR were analyzed. All individuals showed 2n = 50, however, different karyotypic formulae were observed. The population of the Água dos Patos stream showed 8m +24sm+6st+12a (NF=88) and the population of lake Igapó, 8m+28sm+4st+10a (NF=90). Nucleolus organizing regions (AgNORs) were ob...

BACKGROUND Varicocelectomy is considered as standard treatment for male infertility for clinical varicocele. The aim of this study is to address the effects of varicocelectomy on semen parameters, chromatin packaging, and pregnancy outcome. MATERIALS AND METHODS This retrospective study was carried out between June 2006 and February 2011 on 145 infertile men with grade II or III varicocele. M...

The aim of this work is to characterize Nephilengys cruentata in relation to the diploid number, chromosome morphology, type of sex determination chromosome system, chromosomes bearing the Nucleolar Organizer Regions (NORs), C-banding pattern, and AT or GC repetitive sequences. The chromosome preparations were submitted to standard staining (Giemsa), NOR silver impregnation, C-banding technique...

Most true lizards (Lacertidae) share a conservative karyotype, consisting of 18 pairs of macrochromosomes and one microchromosome pair. Homeologues of the microchromosome are present in other squamates and even in chickens. No structural autosomal microchromosome polymorphisms have been described previously in lizards. We found homozygous and heterozygous carriers of a microchromosome variant i...