2,222 research outputs found
Interleukin-18 is expressed in rat testis and may promote germ cell growth
No full textMona-Lisa Strand, Aida Wahlgren, Konstantin Svechnikov, Cecilia Zetterstroma, Brian P. Setchell, Olle Sode
Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis
No full textAbstractThe D-isomer of aspartic acid (D-Asp) has been found in rat testes. In the present study, samples of testicular venous blood plasma, rete testis fluid, interstitial extracellular fluid, luminal fluid from the seminiferous tubules, testicular parenchymal cells, epididymal spermatozoa and peripheral blood plasma were collected and analyzed for D-Asp by two methods, an enzymatic and a chromatographic HPLC method. The two methods gave very similar results for all samples. The highest concentrations of D-Asp (about 120 nmol/ml) were found in testicular venous blood plasma, with slightly lower concentrations in rete testis fluid (95 nmol/ml) and epididymal spermatozoa (80 nmol/g wet weight). Lower levels were found in testicular parenchymal cells (which would comprise mostly spermatids and spermatocytes), luminal fluid from the seminiferous tubules and interstitial extracellular fluid (26, 23 and 11 nmol/ml respectively). However, these values were all higher than those for peripheral blood plasma (6 nmol/ml). It would appear that D-Asp is being secreted by the testis mostly into the venous blood, passing thence into the rete testis fluid and being incorporated into the spermatozoa at the time or after they leave the testis. The distribution of D-Asp is thus quite different from that of testosterone, and its role and the reason for its high concentration in the male reproductive tract remain to be elucidated
SIRT6 in mouse spermatogenesis is modulated by diet-induced obesity
No full textMale obesity is associated with reduced sperm function and increased incidence of sperm DNA damage; however, the underlying molecular mechanisms have not yet been identified. Mammalian SIRT6 protein is involved in caloric-dependant DNA damage repair in other tissue types, yet a possible role for SIRT6 in male obesity and subfertility has not been investigated previously. To assess SIRT6 levels and activity in the testes, male mice (n = 12 per diet) were fed either a control diet (CD; 6% fat) or a high-fat diet (HFD; 21% fat) for 16 weeks before the collection of testes and spermatozoa. SIRT6 protein was localised to the nucleus of transitional spermatids and the acrosome of mature spermatozoa, with levels significantly decreased in HFD-fed male mice (P < 0.05). This decrease in SIRT6 protein was associated with transitional spermatids having increased levels of acetylated H3K9 in the nucleus (P < 0.01) and increased DNA damage (P < 0.001). We propose a role for SIRT6 in spermiogenesis and potentially protamination processes, which are known to be compromised by male obesity.Nicole O. Palmer, Tod Fullston, Megan Mitchell, Brian P. Setchell and Michelle Lan
Whole-body heat exposure induces membrane changes in spermatozoa from the cauda epididymidis of laboratory mice
No full textThis study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice (n = 7) were housed in a microclimate chamber at 37ºC–38ºC for 8 h per day for three consecutive days, while control mice (n = 7) were kept at 23ºC–24ºC. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups (P = 0.23), but after heat treatment, a significant reduction in the percentage of motile sperm was present (P < 0.0001). Membrane changes of the spermatozoa were investigated by staining with phycoerythrin (PE)- conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D (7-AAD), which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V–PE or 7-AAD or both, was significantly higher (P < 0.05) in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37ºC–38ºC induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.Harsha Wechalekar, Brian P. Setchell, Eleanor J. Peirce, Mario Ricci, Chris Leigh and William G. Bree
Improving metabolic health in obese male mice via diet and exercise restores embryo development and fetal growth
No full textPaternal obesity is now clearly associated with or causal of impaired embryo and fetal development and reduced pregnancy rates in humans and rodents. This appears to be a result of reduced blastocyst potential. Whether these adverse embryo and fetal outcomes can be ameliorated by interventions to reduce paternal obesity has not been established. Here, male mice fed a high fat diet (HFD) to induce obesity were used, to determine if early embryo and fetal development is improved by interventions of diet (CD) and/or exercise to reduce adiposity and improve metabolism. Exercise and to a lesser extent CD in obese males improved embryo development rates, with increased cell to cell contacts in the compacting embryo measured by E-cadherin in exercise interventions and subsequently, increased blastocyst trophectoderm (TE), inner cell mass (ICM) and epiblast cell numbers. Implantation rates and fetal development from resulting blastocysts were also improved by exercise in obese males. Additionally, all interventions to obese males increased fetal weight, with CD alone and exercise alone, also increasing fetal crown-rump length. Measures of embryo and fetal development correlated with paternal measures of glycaemia, insulin action and serum lipids regardless of paternal adiposity or intervention, suggesting a link between paternal metabolic health and subsequent embryo and fetal development. This is the first study to show that improvements to metabolic health of obese males through diet and exercise can improve embryo and fetal development, suggesting such interventions are likely to improve offspring health.Nicole O. McPherson, Hassan W. Bakos, Julie A. Owens, Brian P. Setchell, Michelle Lan
‘Through the unknown, remembered gate’: the Brian Nettleton lecture – Outdoors Victoria conference, 2022
No full textThis paper is an adapted version of the Brian Nettleton Lecture given at the Outdoors Victoria Conference, 2022. It explores how the last two decades have seen an ever-accelerating Digital Revolution which has impacted on almost every aspect of human experience to the point that it is now omnipresent. Life is now mediated through the screen. As a result, children and young people have become hyper-vigilant, overly anxious, experience a sense of climate trauma, and have decreasing access to, and time spent in, the outdoors. In addition, children have just experienced two years of isolation as a result of the Covid-19 pandemic and evidence suggests that they are already experiencing significant mental health issues as a result. This paper considers the implications of this for Outdoors Victoria and Outdoor Education. © The Author(s) 2023
Partitioning of gases to ice in the atmosphere: effects on nitric acid and the formation of sulfate
No full textThis thesis describes the first implementation of gas-to-ice partitioning of three inorganic gases (HNO3, SO2 and H2O2), along with subsequent chemical reactions and changes in gas phase and particle mass concentrations in the Community Multiscale Air Quality (CMAQ) chemical transport model. Adsorbed HNO3 was assumed to condense and partition to the aerosol phase. Adsorbed SO2 and H2O2 reacted to form sulfate on the ice surface. Four different simulations were performed with CMAQv4.7.1 for August 12th-25th of 2005: 1) base case simulation without the addition of lightning-generated NOx, 2) a simulation with the addition of lightning-generated NOx, 3) 100% partitioning case and 4) 25% partitioning case. Simulations 3) and 4) provided an upper and lower bound for the partitioning of adsorbed HNO3 to remain in the aerosol phase. Considerable decreases, greater than 25% in gas phase HNO3, were noted in the 100% partitioning case for 200-600 mb, with the largest changes at 300 mb and 400 mb. Potential effects induced on other gases in the nitrogen budget (NOx and HONO) and oxidant cycling of atmosphere (O3) due to gas-to-ice partitioning of HNO3 were considered. Decreases in NOx and HONO gas mixing ratios were found to be as high 20%, but were generally less than 10%. Changes in O3 concentration were less than 1%. Increases in nitrate aerosol mass concentration were as high as 0.15 µg/m3 for the upper levels of the atmosphere. No changes in H2O2, SO2, or sulfate aerosol concentrations were observed.M.S.Includes bibliographical referencesby Brian P. Marm
The recycling of carbon in glucose, lactate and alanine in sheep
No full textPregnant ewes with catheters implanted in an artery and the uterine and recurrent tarsal veins were infused at a constant rate with U−¹⁴C-labelled glucose, alanine or bicarbonate. Measurements were made of the overall and local fractional contribution of glucose and alanine to CO₂ production and of the extent of interconversion of these metabolites. In the whole animal, by coupling the results with the authors’ previous study of lactate metabolism, a solution was obtained to an open unrestricted 4-compartment model of the exchange of carbon between glucose, lactate, alanine and CO₂. A more limited study was made with non-pregnant sheep because complete data for lactate interactions with alanine were not available. Our analysis of glucose/lactate/alanine/CO₂ interactions in pregnant sheep suggests that about two-thirds of the glycogenic carbon was oxidised fairly directly to CO₂. There was relatively little recycling of glucose carbon through lactate and alanine so that most of the remaining glycogenic carbon was stored as product with relatively long turnover time. It is possible that much of this was in the form of muscle glycogen, and analysis of glycogenic carbon exchange across the hind limb muscle was consistent with this conclusion. In non-pregnant ewes, the findings, although incomplete, suggested that there were no great differences from the findings in pregnant ewes.Derek B. Lindsay, Patrick J. Barker, Andrew J. Northrop, Brian P. Setchell, Graham J. Faichne
In Honour of Brian MacWhinney: A Personal Account
No full textWhile this volume and the writings have made it amply clear what significant contributions Professor Brian MacWhinney has made to the field at large, in this afterword, we begin with a senior member of our author team (Ping Li, PL) followed by a mid-career member (Helen Zhao, HZ) and an early career member (Zhe Gao, ZG), to provide our personal accounts of Brian not only as a leading scholar but also as a role model who touches and changes people’s lives
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