Revisiting summer infertility in the boar: impact of heat stress on the quality and DNA integrity of spermatozoa, and its mitigation by antioxidant therapy

Summer infertility in the pig continues to affect both productivity and profitability among pig producers in tropical and subtropical regions, with losses due to heat stress amounting to at least $300 million per year in the US swine industry alone. Given the wide scale production of pork globally, with at least five tropical countries among the top producers in the world, there is a need to revisit the problem of summer infertility in the pig and identify putative boar factors likely to contribute to poor reproductive performance during periods of heat stress. An important endpoint with this approach is to improve boar management practices and develop strategies to mitigate summer infertility in the pig. While the scrotum, pampiniform plexus, and cremaster and dartos muscles in mammals are specific adaptations to ensure sperm production in a regulated environment 4-6 °C below body temperature, the boar's inefficient capacity to sweat, non-pendulous scrotum, and low antioxidant activity in the semen, can make the it particularly vulnerable to the effects of heat stress. In Chapter 2, we demonstrated for the first time the link between summer heat stress and sperm DNA damage in Large White boars. Boars raised in the dry tropics of Townsville, Queensland, Australia during summer (peak wet) showed 16-fold more sperm DNA damage than early dry (cool and dry), and nearly 9-fold more than the late dry (warm and humid) season, respectively. Sperm concentration also decreased significantly in the peak wet. Sperm DNA damage has been previously demonstrated to contribute to early embryonic death in the mouse, and this magnitude of fragmentation is known to cause a reduction in litter size in sows. These findings provide impetus for the evaluation of sperm DNA integrity in commercial boar herds housed in the tropics as a putative contributing factor to seasonal infertility in the sow. While cryopreservation of boar spermatozoa is not widely practiced in commercial pig production, mostly due to reduced viability and fertilising capacity of post-thawed spermatozoa, it has a greater potential in advancing studies related to seasonal effects of heat stress on boar sperm fertility using in vitro fertilisation. Since the freeze-thaw process can led to increased sperm DNA damage and subsequently contribute to early embryo loss, in Chapter 3 we tried to address the limited information about the protective effects of the more common cryoprotectant glycerol on sperm DNA integrity during boar sperm cryopreservation. We aimed to determine the optimal concentration of glycerol to protect sperm DNA integrity, without the deleterious effect of high concentrations negatively affecting sperm motility. We deemed this work particularly important to permit us to freeze boar sperm collected during summer, for downstream use to fertilise eggs in vitro during winter when oocyte quality is high. Our study revealed that 3%, 6% or 8% glycerol could be safely used to cryopreserve boar spermatozoa without inducing additional DNA damage compared to fresh spermatozoa. We deemed a concentration of 6% glycerol provided the best DNA protection, while maintaining sufficient levels of sperm motility. In chapter 4, we aimed to develop reliable heat stress models that could be used at any time of the year, to advance the study of seasonal infertility in the pig by overcoming the variation and limitations associated with seasonal studies. We have successfully induced biologically meaningful levels of DNA damage in boar spermatozoa using either a whole animal in vivo model (hot room) or by direct exposure of semen to heat in vitro (heat shock model). However, we were only able to induce levels of damage observed during natural tropical summer (Chapter 2) using extreme in vitro temperatures that rendered boar spermatozoa completely immotile or dead. Here, our results suggest that boar sperm is vulnerable to heat-induced DNA damage, but individual factors may also contribute to a boar's overall susceptibility to heat stress. Given the limited endogenous levels of antioxidants in boar semen and the insufficient DNA repair mechanisms these cells have, Chapter 5 aimed to formulate and evaluate antioxidant therapy as a strategy to mitigate the effect of heat stress on boar sperm DNA integrity. We proposed that an exogenous multi-compound antioxidant supplementation could effectively combat heat stress induced oxidative damage and prevent the build-up of DNA fragmentation in boar spermatozoa. Supplementing boar diets with 100 g/day custom-mixed antioxidant during summer effectively reduced sperm DNA damage by as much as 55% after 42 and 84 days treatment, respectively. This implies that antioxidant supplementation during tropical summer could provide a measurable solution to the problem of boar-mediated summer infertility in the pig. Overall, boar sperm DNA integrity can be compromised during tropical summer and this can be induced experimentally using our in vivo or in vitro heat stress models; with response particularly affected by individual boar variability. Exogenous antioxidant supplementation in feed could provide an effective means to mitigate the problem of summer infertility. Apparently, neither seasonal heat stress or heat stress models negatively affected sperm motility, suggesting that traditional evaluation of sperm motility in boars may not detect inherently compromised DNA damage spermatozoa. Antioxidant supplementation only appears to mitigate DNA damage since it did not improve sperm motility or concentration after 42 or 84 days treatment. Future studies are needed to measure the beneficial impact of antioxidant supplementation under tropical farm conditions, in terms of improved sperm DNA integrity and increased litter size following artificial insemination

Biosecurity and readiness of smallholder pig farmers against potential African Swine Fever outbreak and other pig diseases in Baybay City, Leyte, Philippines

Preventing African Swine Fever (ASF) outbreaks require an active involvement of pig growers as they are in the frontline of detection, notification, and the application of strict biosecurity measures. The Eastern Visayas (Region VIII) in Central Philippines is still free of ASF but the risk can be remarkable given the high volume of pigs that enter in this region as a market hub to large pig producers both coming from Luzon (north) and Mindanao (south). This study was conducted to better understand the readiness and biosecurity practices of smallholder pig farmers who comprise most of the pig growers in the City of Baybay, Leyte. Using multiple correspondence analysis (MCA) and agglomerative hierarchical clustering (AHC) technique of data from 350 pig farmer-respondents, our study found several areas in pig raising activities that need to be highlighted. While pig farmers were generally aware of the threat posed by ASF and have relatively good biosecurity practices, only 32.90% were convinced that the City of Baybay is prepared in the case of an ASF outbreak. Moreover, the importance of vaccination, footbath, and controlling swill feeding need to be emphasized (Cluster 2, 58.29%).  More efforts should be directed towards preparing and training pig farmers on disease monitoring and surveillance and improving further its biosecurity practices with special focus on bioexclusion. Similar studies should be conducted to nearby local government units particularly those located near entry and exit borders of the Eastern Visayas region

Tropical summer induces DNA fragmentation in boar spermatozoa: implications for evaluating seasonal infertility

Summer infertility continues to undermine pig productivity, costing the pig industry millions in annual losses. The boar’s inefficient capacity to sweat, non-pendulous scrotum and the extensive use of European breeds in tropical conditions, can make the boar particularly vulnerable to the effects of heat stress; however, the link between summer heat stress and boar sperm DNA damage has not yet been demonstrated. Semen from five Large White boars was collected and evaluated during the early dry, late dry and peak wet seasons to determine the effect of seasonal heat stress on the quality and DNA integrity of boar spermatozoa. DNA damage in spermatozoa during the peak wet was 16-fold greater than during the early dry and nearly 9-fold greater than during the late dry season. Sperm concentration was 1.6-fold lower in the peak wet than early dry whereas no difference was found across several motility parameters as determined by computer-assisted sperm analysis. These results demonstrate that tropical summer (peak wet season) induces DNA damage and reduces concentration without depressing motility in boar spermatozoa, suggesting that traditional methods of evaluating sperm motility may not detect inherently compromised spermatozoa. Boar management strategies (such as antioxidant supplementation) need to be developed to specifically mitigate this problem

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

Abstract: We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star–black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of 105, 106, 107Mpc3 for binary neutron star, neutron star–black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of 1-1+12(10-10+52) for binary neutron star mergers, of 0-0+19(1-1+91) for neutron star–black hole mergers, and 17-11+22(79-44+89) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030