Deuterium retention and erosion in liquid Sn samples exposed to D2 and Ar plasmas in GyM device

The use of tin (Sn) as a liquid metal for plasma facing components has been recently proposed as a solution to the high heat load issue on the divertor target plates in nuclear fusion reactors. Due to its low vapor pressure, low reactivity with hydrogen and good resilience to neutron impact, tin is a good candidate as plasma facing component. However its high atomic number poses concerns about plasma contamination.In this paper two fundamental aspects have been investigated: deuterium retention and erosion fluxes from the Sn surface towards the plasma. The samples were exposed to plasma inside the linear machine GyM in magnetic cusp configuration. This setup permits to expose free liquid specimens without the need for the Capillary Porous System. Moreover it permits to lower the magnetic field in order to increase Sn Larmor radius and consequently limit Sn re-deposition in erosion experiments.Ex-situ analyses by ion beam diagnostics on solid samples exposed to deuterium plasma have proved that the amount of retained atomic deuterium is very low, approximately 0.18 at% estimated by Nuclear Reaction Analysis and 0.25 at% estimated by Elastic Recoil Detection Analysis.In the framework of erosion studies, the spectroscopic parameter S/XB was evaluated in Ar plasma for the SnI line at 380.1 nm by Optical Emission Spectroscopy and mass loss measurements in the 5–11 eV Te range, at a density ne ∼ 1.5 × 1011 cm−3. An average value of 150 ± 23 was obtained. Keywords: Liquid metals, Deuterium retention, Erosion, Double-cusp magnetic configuration, Ion beam diagnostics, S/XB spectroscopic paramete

The relationship between seminal leukocytes, oxidative status in the ejaculate, and apoptotic markers in human spermatozoa

The aim of this study was to investigate the relationship between seminal leukocytes, reactive oxygen species (ROS) production in the ejaculate, and markers of apoptosis in human spermatozoa. Semen samples were collected from 60 patients attending fertility clinics at the Reproductive Biology Unit at Tygerberg Academic Hospital and Vincent Pallotti Hospital, Cape Town, South Africa. The concentration of seminal leukocytes was determined and was correlated with ROS production in the ejaculate, the percentage of superoxide (·O2 )- and hydrogen peroxide (H2O2)-positive spermatozoa, glutathione activation in the ejaculate, and with markers of apoptosis in spermatozoa, namely cysteine-dependent aspartate-directed proteases (caspase)-3/7 activation, mitochondrial membrane potential (ΔΨm), and the percentage of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive sperm. Significant correlations with the concentration of seminal leukocytes were found for ROS production in the ejaculate, the percentage of ·O2 -positive spermatozoa, and caspase-3/7 activation in the ejaculate. Leukocytospermic samples showed significantly higher ROS production, percentage of ·O2 -positive sperm, GSH activation, and caspase-3/7 activation compared to non-leukocytospermic samples. The percentage of ·O2 -positive sperm was significantly correlated with sperm ΔΨm and caspase-3/7 activation in the ejaculate. Sperm ΔΨm and TUNEL-positive sperm did not correlate with seminal leukocyte concentration. Data demonstrate that high seminal leukocyte concentrations that leads to increased seminal ROS production, and is also associated with caspase activation in the male germ cell and increased mitochondrial ROS production. The latter could possibly be a result of disturbed ΔΨm. The activation of caspase-3/7 could then follow the increased intrinsic superoxide levels due to depleted intrinsic glutathione (GSH). These cellular events might not directly and immediately lead to DNA fragmentation as an endpoint of apoptosis because of topological hindrances.Web of Scienc

Chewing Through the Miocene: An Examination of the Feeding Musculature in the Ground Sloth Hapalops from South America (Mammalia: Pilosa)

Hapalops, a smaller-sized and early sloth of the Megatheroidea, appeared in the middle Miocene Santa Cruz formation of Argentina. This genus is part of the group from which later, larger megatheroids arose, i.e., Nothrotheriops and Megatherium. Many cranial characters support this idea; however Hapalops is not merely a smaller antecedent of the later forms. Specifically, Hapalops retains short anterior caniniform teeth, and a temporomandibular joint elevated above the cheek tooth row; a combination distinct among sloths. An elevated temporomandibular joint occurs in Bradypus, a tree sloth with anterior chisel-shaped teeth instead of caniniforms, and the tree sloth Choloepus, which is aligned with the megalonychids, has anterior caniniforms. Hapalops has an elongated zygomatic ascending process that is reminiscent of that in Bradypus; however, the Bradypus skull is extremely foreshortened while that of Hapalops is elongated, as in nothrotheres, but not deepened as in megatheres. Previous work identified many sloth cranial character complexes, and functional limitations on skull feature combinations. The unique Hapalops character patterns indicate a selective feeder with a mediolaterally oriented grinding stroke during mastication

Spermatozoal sensitive biomarkers to defective protaminosis and fragmented DNA

Human sperm DNA damage may have adverse effects on reproductive outcome. Infertile men possess substantially more spermatozoa with damaged DNA compared to fertile donors. Although the extent of this abnormality is closely related to sperm function, the underlying etiology of ensuing male infertility is still largely controversial. Both intra-testicular and post-testicular events have been postulated and different mechanisms have been proposed to explain the presence of damaged DNA in human spermatozoa. Three among them, i.e. abnormal chromatin packaging, oxidative stress and apoptosis, are the most studied and discussed in the present review. Furthermore, results from numerous investigations are presented, including our own findings on these pathological conditions, as well as the techniques applied for their evaluation. The crucial points of each methodology on the successful detection of DNA damage and their validity on the appraisal of infertile patients are also discussed. Along with the conventional parameters examined in the standard semen analysis, evaluation of damaged sperm DNA seems to complement the investigation of factors affecting male fertility and may prove an efficient diagnostic tool in the prediction of pregnancy outcome

Radiations and male fertility

During recent years, an increasing percentage of male infertility has to be attributed to an array of environmental, health and lifestyle factors. Male infertility is likely to be affected by the intense exposure to heat and extreme exposure to pesticides, radiations, radioactivity and other hazardous substances. We are surrounded by several types of ionizing and non-ionizing radiations and both have recognized causative effects on spermatogenesis. Since it is impossible to cover all types of radiation sources and their biological effects under a single title, this review is focusing on radiation deriving from cell phones, laptops, Wi-Fi and microwave ovens, as these are the most common sources of non-ionizing radiations, which may contribute to the cause of infertility by exploring the effect of exposure to radiofrequency radiations on the male fertility pattern. From currently available studies it is clear that radiofrequency electromagnetic fields (RF-EMF) have deleterious effects on sperm parameters (like sperm count, morphology, motility), affects the role of kinases in cellular metabolism and the endocrine system, and produces genotoxicity, genomic instability and oxidative stress. This is followed with protective measures for these radiations and future recommendations. The study concludes that the RF-EMF may induce oxidative stress with an increased level of reactive oxygen species, which may lead to infertility. This has been concluded based on available evidences from in vitro and in vivo studies suggesting that RF-EMF exposure negatively affects sperm quality

Acrosomal integrity, viability, and DNA damage of sperm from dasyurid marsupials after freezing or freeze drying

Dasyurids are a diverse group of Australian native carnivores and insectivores that contains several threatened species. Despite successful cryopreservation of sperm from several marsupials, only 3% postthaw motility is reported for dasyurid marsupials. This study examined sperm preservation in the fat-tailed dunnart (Sminthopsis crassicaudata), an experimental model, with supplementary observations on the eastern quoll (Dasyurus viverrinus) and northern quoll (Dasyurus hallucatus). In S. crassicaudata, a toxicity trial demonstrated that incubation with up to 40% glycerol did not reduce sperm viability, suggesting that glycerol is not toxic to dasyurids. On the basis of this finding, S. crassicaudata, D. viverrinus, and D. hallucatus sperm were extended to a final concentration of 20% or 40% glycerol in Tris-citrate fructose and frozen in liquid nitrogen vapor. Postthaw sperm from all three species were nonmotile, and vital staining (SYBR14 and propidium iodide) indicated that sperm were nonviable. However, there was no evidence suggesting disruption of normal gross morphology or loss of acrosomal integrity when assessed by Bryan's staining. After freeze drying, Bryan's staining indicated that approximately 80% of S. crassicaudata sperm had normal acrosomes and no head loss. Despite being nonviable, terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling showed that S. crassicaudata sperm frozen in 40% glycerol or freeze-dried had no DNA damage compared with fresh controls. This study has described a method for preservation of the dasyurid sperm nuclei, but continued studies are required to achieve viable motile sperm and establish tools for the long-term storage of dasyurid sperm

The source and significance of DNA damage in human spermatozoa; a commentary on diagnostic strategies and straw man fallacies

This article considers the origins of DNA damage in human spermatozoa, the methods that are available to monitor this aspect of semen quality and the clinical significance of such measurements. DNA damage in spermatozoa appears to be largely oxidative in nature, inversely correlated with levels of nuclear protamination and frequently associated with the activation of a truncated apoptotic pathway. DNA base adducts formed as a result of oxidative attack are released from the spermatozoa into the extracellular space through the action of a glycosylase, OGG1. This creates an abasic site, which is not resolved until fertilization because spermatozoa do not possess the molecular machinery needed to continue the base excision repair pathway. The abasic sites so generated in human spermatozoa are readily detected by SCSA or the Comet assay; however, no signal is detectable with TUNEL. This is because spermatozoa lack the enzyme (APE1) needed to create the free 3′ hydroxyl groups required by this detection system. Nevertheless, spermatozoa do eventually become TUNEL positive as they enter the perimortem. The American Society of Reproductive Medicine Practice Committee has suggested that DNA damage in spermatozoa should not be assessed because the correlation with pregnancy is inconsistent across independent studies. However, this is a straw man argument. The reason why such assays should be undertaken is not just that they reflect the underlying quality of spermatogenesis but, more importantly, that the DNA damage they reveal may have detrimental effects on the developmental normality of the embryo and the health of possible future children

The senescence-accelerated mouse prone 8 as a model for oxidative stress and impaired DNA repair in the male germ line

The discovery of a truncated base excision repair pathway in human spermatozoa mediated by OGG1 has raised questions regarding the effect of mutations in critical DNA repair genes on the integrity of the paternal genome. The senescence-accelerated mouse prone 8 (SAMP8) is a mouse model containing a suite of naturally occurring mutations resulting in an accelerated senescence phenotype largely mediated by oxidative stress, which is further enhanced by a mutation in the Ogg1 gene, greatly reducing the ability of the enzyme to excise 8-hydroxy,2′-deoxyguanosine (8OHdG) adducts. An analysis of the reproductive phenotype of the SAMP8 males revealed a high level of DNA damage in caudal epididymal spermatozoa as measured by the alkaline Comet assay. Furthermore, these lesions were confirmed to be oxidative in nature, as demonstrated by significant increases in 8OHdG adduct formation in the SAMP8 testicular tissue (P<0.05) as well as in mature spermatozoa (P<0.001) relative to a control strain (SAMR1). Despite this high level of oxidative DNA damage in spermatozoa, reactive oxygen species generation was not elevated and motility of spermatozoa was found to be similar to that for the control strain with the exception of progressive motility, which exhibited a slight but significant decline with advancing age (P<0.05). When challenged with Fenton reagents (H₂O₂ and Fe²⁺), the SAMP8 spermatozoa demonstrated a highly increased susceptibility to formation of 8OHdG adducts compared with the controls (P<0.001). These data highlight the role of oxidative stress and OGG1-dependent base excision repair mechanisms in defining the genetic integrity of mammalian spermatozoa