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Condensation Status (condensation + status)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Nuclear aggregates of polyamines

IUBMB LIFE, Issue 2 2006
Luciano D'Agostino
Abstract Nuclear aggregates of polyamines (NAPs) are cyclic supramolecular compounds made of polyamines and phosphate groups. Three different aggregates, s-NAP, m-NAP and l-NAP, with a molecular weight of 1035, 5175 and 9552 Da, respectively, are described. These molecules interact with genomic DNA. In consequence of this interaction, NAPs not only protect DNA from nucleases with extraordinarily greater efficiency than single polyamines (spermine, spermidine and putrescine), but also induce noticeable changes in DNA condensation status, as shown by temperature-dependent modifications of DNA electrophoretic properties. The biochemical characterization of these compounds has allowed the definition of a structural model for each NAP. According to this model, five s-NAPs assemble together to form a m-NAP unit. We hypothesize that the complexation of s-NAP into m-NAP favours the transition to Z-DNA through the progressive widening of DNA strands and the exposure of bases. We propose that NAPs, by wrapping the DNA helixes, form supramolecular tunnel-like structures that confer efficient protection without affecting DNA elasticity. iubmb Life, 58: 75-82, 2006 [source]

Effect of Ram Age on Structural and Functional Competence of Frozen,Thawed Spermatozoa in Dairy Sheep

REPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2010
AG Lymberopoulos
Contents The objectives of this study were to investigate the influence of ram age on structural and functional competence of frozen,thawed spermatozoa and to test the hypothesis that increasing number of sperm bound to the zona pellucida in vitro was associated with decreasing in vivo fertility of frozen semen. Rams were allocated into two groups. Each group consisted of five rams aged either 1,2 years (young) or 4,5 years (mature). Three successive ejaculates were collected from each ram using an artificial vagina. Only ejaculates of , 2.5 × 109 sperm/ml and 80% sperm progressive motility were pooled per ram, diluted with Bioxcell® medium and frozen in 0.25 ml straws. The end points of post-thawing semen evaluation were computer-assisted cell motility analysis, sperm capacitation (chlortetracycline assay), simultaneous assessment of plasma membrane integrity, mitochondrial membrane potential and condensation status of nucleus, per-cell analysis of lipid peroxidation using C11-BODIPY581/591, sperm-hemizona binding (HZB) ability and sperm fertility after laparoscopic insemination of ewes (n = 114) in the progestagen-synchronized oestrus. The results showed that mature rams had significantly lower values of sperm hyperactivated motility and peroxidized sperm, higher percentages of live non-capacitated sperm and sperm cells with intact plasma membrane, functional mitochondria and condensed chromatin, as well as, greater lambing rate and ewe prolificacy. Sperm HZB binding ability was higher (p < 0.05) for young than for mature rams. Significant correlations were found between number of spermatozoa bound to the zona pellucida and semen fertility (r = ,0.63 to ,0.71). In conclusion, mature rams have better semen quality and in vivo fertility than young rams. Cryocapacitation can be involved in decreasing ram semen fertility as evidenced by the high number of spermatozoa bound to the zona pellucida in vitro. [source]

Histone H1 and MAP Kinase Activities in Bovine Oocytes following Protein Synthesis Inhibition

REPRODUCTION IN DOMESTIC ANIMALS, Issue 3-4 2001
B Meinecke
In vitro nuclear maturation is associated with known activity profiles of the M-phase promoting factor (MPF) and the mitogen-activated protein (MAP) kinases, which are two key regulators of mitotic and meiotic cell cycles. Initiation of meiotic resumption in vitro can be prevented by cycloheximide treatment and after removal of the inhibitor germinal vesicle breakdown takes place nearly twice as fast as in untreated controls. In this study experiments were conducted in order to examine the chromosome condensation status and the dynamics of MPF and MAP kinase activities after cycloheximide treatment (10 ,g/ml) of cumulus-enclosed oocytes for 17 and 24 h, respectively, and subsequent culture in inhibitor-free medium for various times. Bovine oocytes displayed variations in the degree of chromosome condensation at the end of the inhibitor treatment phase. Following removal of the inhibitor germinal vesicle breakdown occurred after 4,5 h of subsequent culture in inhibitor-free medium. MPF and MAP kinase exhibited low activities during the first 1,3 h following cycloheximide treatment. Increasing levels of enzyme activities were detected 4,7 h following cycloheximide treatment for 17 and 24 h, respectively, and subsequent culture in inhibitor-free medium. The patterns of enzyme activities corresponded with the accelerated nuclear maturation process. It can be concluded that cycloheximide treatment does not lead to a more synchronous course of nuclear maturation and that the activities of both, MPF and MAP kinase are initiated at least 2,5 h earlier in comparison with untreated oocytes. [source]

Leucocytes and intrinsic ROS production may be factors compromising sperm chromatin condensation status

ANDROLOGIA, Issue 2 2010
R. Henkel
Summary Considering that the final protection of the DNA against major assaults in terms of chromatin condensation is finalised in the epididymis, it is not known how sperm production of reactive oxygen species (ROS) and inflammatory processes can contribute to protamine deficiency that is predetermined in the testes. Therefore, this study aimed at investigating relationships between poor chromatin condensation, morphology, ROS production, DNA damage and the impact of the presence of leucocytes. In 70 patients, sperm DNA status was determined using TUNEL and chromomycin A3 (CMA3) assays, and ROS-production by means of dihydroethidine. Morphology was evaluated according to strict criteria. The percentage of CMA3 -positive spermatozoa and leucocyte concentration (r = 0.178, P = 0.0377) as well as percentage of ROS-positive spermatozoa (r = 0.3010; P = 0.012) correlated significantly. Particularly, patients with leucocyte counts >0.5 × 106 ml,1 exhibited higher CMA3 positivity. No association was found between CMA3 positivity, TUNEL positivity and sperm morphology. While P- (poor prognosis: 0,4% normal morphology) and G-pattern (good prognosis: 5,14% normal morphology) morphology did not differ regarding chromatin condensation, P-pattern patients had a significantly higher percentage of DNA fragmentation (P = 0.0323). As oxidative stress is associated with disturbed chromatin condensation, results suggest that the idea that under-protamination of sperm DNA will automatically lead to DNA fragmentation might have to be revisited. [source]