bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selfish genetic elements and male fertility
Authors: Verspoor Rudi L. , Price Tom A. R. , Wedell Nina 
Published: October 2020

Selfish genetic elements (SGEs) are diverse and near ubiquitous in Eukaryotes and can be potent drivers of evolution. Here, we discuss SGEs that specifically act on sperm to gain a transmission advantage to the next generation. The diverse SGEs that affect sperm often impose costs on carrier males, including damaging ejaculates, skewing offspring sex ratios and in particular reducing sperm-competitive success of SGE-carrying males. How males and females tolerate and mitigate against these costs is a dynamic and expanding area of research. The intense intra-genomic conflict that these selfish elements generate could also have implications for male fertility and spermatogenesis more widely.This article is part of the theme issue ‘Fifty years of sperm competition’.
Sexual selection after gamete release in broadcast spawning invertebrates
Authors: Evans Jonathan P. , Lymbery Rowan A. 
Published: October 2020

Broadcast spawning invertebrates offer highly tractable models for evaluating sperm competition, gamete-level mate choice and sexual conflict. By displaying the ancestral mating strategy of external fertilization, where sexual selection is constrained to act after gamete release, broadcast spawners also offer potential evolutionary insights into the cascade of events that led to sexual reproduction in more ‘derived’ groups (including humans). Moreover, the dynamic reproductive conditions faced by these animals mean that the strength and direction of sexual selection on both males and females can vary considerably. These attributes make broadcast spawning invertebrate systems uniquely suited to testing, extending, and sometimes challenging classic and contemporary ideas in sperm competition, many of which were first captured in Parker's seminal papers on the topic. Here, we provide a synthesis outlining progress in these fields, and highlight the burgeoning potential for broadcast spawners to provide both evolutionary and mechanistic understanding into gamete-level sexual selection more broadly across the animal kingdom.
This article is part of the theme issue ‘Fifty years of sperm competition’.
Sperm competition and fertilization mode in fishes
Authors: Fitzpatrick John L. 
Published: October 2020

Sperm competition is a powerful selective force that has shaped sexual traits throughout animal evolution. Yet, how fertilization mode (i.e. external versus internal fertilization) influences the scope and potential for sperm competition to act on ejaculates remains unclear. Here, I examine how fertilization mode shapes ejaculatory responses to sperm competition in fishes, a diverse group that constitute the majority of vertebrate biological diversity. Fishes are an ideal group for this examination because they exhibit a wide range of reproductive behaviours and an unparalleled number of transitions in fertilization mode compared to any other vertebrate group. Drawing on data from cartilaginous and bony fishes, I first show that rates of multiple paternity are higher in internally than externally fertilizing fishes, contrary to the prevailing expectation. I then summarize how sperm competition acts on sperm number and quality in internally and externally fertilizing fishes, highlighting where theoretical predictions differ between these groups. Differences in how ejaculates respond to sperm competition between fertilization modes are most apparent when considering sperm size and swimming performance. Clarifying how fertilization mode influences evolutionary responses in ejaculates will inform our understanding of ejaculate evolution across the animal tree of life.This article is part of the theme issue ‘Fifty years of sperm competition’.
Sperm and alternative reproductive tactics: a review of existing theory and empirical data
Authors: Kustra Matthew C. , Alonzo Suzanne H. 
Published: October 2020

Males that exhibit alternative reproductive tactics (ARTs) often differ in the risk of sperm competition and the energetic trade-offs they experience. The resulting patterns of selection could lead to between-tactic differences in ejaculate traits. Despite extensive research on male ARTs, there is no comprehensive review of whether and what differences in sperm traits exist between male ARTs. We review existing theory on ejaculate evolution relevant to ARTs and then conduct a comprehensive vote-counting review of the empirical data comparing sperm traits between males adopting ARTs. Despite the general expectation that sneaker males should produce sperm that are more competitive (e.g. higher quality or performance), we find that existing theory does not predict explicitly how males adopting ARTs should differ in sperm traits. The majority of studies find no significant difference in sperm performance traits between dominant and sneaker males. However, when there is a difference, sneaker males tend to have higher sperm performance trait values than dominant males. We propose ways that future theoretical and empirical research can improve our understanding of the evolution of ejaculate traits in ARTs. We then highlight how studying ejaculate traits in species with ARTs will improve our broader knowledge of ejaculate evolution.This article is part of the theme issue ‘Fifty years of sperm competition’.
The role of female reproductive fluid in sperm competition
Authors: Gasparini Clelia , Pilastro Andrea , Evans Jonathan P. 
Published: October 2020

The role of non-gametic components of the ejaculate (seminal fluid) in fertility and sperm competitiveness is now well established. Surprisingly, however, we know far less about female reproductive fluid (FRF) in the context of sexual selection, and insights into male–FRF interactions in the context of sperm competition have only recently emerged. Despite this limited knowledge, evidence from taxonomically diverse species has revealed insights into the effects of FRF on sperm traits that have previously been implicated in studies of sperm competition. Specifically, through the differential effects of FRF on a range of sperm traits, including chemoattraction and alterations in sperm velocity, FRF has been shown to exert positive phenotypic effects on the sperm of males that are preferred as mating partners, or those from the most compatible or genetically diverse males. Despite these tantalizing insights into the putative sexually selected functions of FRF, we largely lack a mechanistic understanding of these processes. Taken together, the evidence presented here highlights the likely ubiquity of FRF-regulated biases in fertilization success across a diverse range of taxa, thus potentially elevating the importance of FRF to other non-gametic components that have so far been studied largely in males.This article is part of the theme issue ‘Fifty years of sperm competition'.
Temporal dynamics of competitive fertilization in social groups of red junglefowl (Gallus gallus) shed new light on avian sperm competition
Authors: Carleial Rômulo , McDonald Grant C. , Spurgin Lewis G. , Fairfield Eleanor A. , Wang Yunke , Richardson David S. , Pizzari Tommaso 
Published: October 2020

Studies of birds have made a fundamental contribution to elucidating sperm competition processes, experimentally demonstrating the role of individual mechanisms in competitive fertilization. However, the relative importance of these mechanisms and the way in which they interact under natural conditions remain largely unexplored. Here, we conduct a detailed behavioural study of freely mating replicate groups of red junglefowl,Gallus gallus, to predict the probability that competing males fertilize individual eggs over the course of 10-day trials. Remating frequently with a female and mating last increased a male's probability of fertilization, but only for eggs ovulated in the last days of a trial. Conversely, older males, and those mating with more polyandrous females, had consistently lower fertilization success. Similarly, resistance to a male's mating attempts, particularly by younger females, reduced fertilization probability. After considering these factors, male social status, partner relatedness and the estimated state of male extragonadal sperm reserves did not predict sperm competition outcomes. These results shed new light on sperm competition dynamics in taxa such as birds, with prolonged female sperm storage and staggered fertilizations.This article is part of the theme issue ‘Fifty years of sperm competition’.
Of mice and women: advances in mammalian sperm competition with a focus on the female perspective
Authors: Firman Renée C. 
Published: October 2020

Although initially lagging behind discoveries being made in other taxa, mammalian sperm competition is now a productive and advancing field of research. Sperm competition in mammals is not merely a ‘sprint-race’ between the gametes of rival males, but rather a race over hurdles; those hurdles being the anatomical and physiological barriers provided by the female reproductive tract, as well as the egg and its vestments. With this in mind, in this review, I discuss progress in the field while focusing on the female perspective. I highlight ways by which sperm competition can have positive effects on female reproductive success and discuss how competitive outcomes are not only owing to dynamics between the ejaculates of rival males, but also attributable to mechanisms by which female mammals bias paternity toward favourable sires. Drawing on examples across different species—from mice to humans—I provide an overview of the accumulated evidence which firmly establishes that sperm competition is a key selective force in the evolution of male traits and detail how females can respond to increased sperm competitiveness with increased egg resistance to fertilization. I also discuss evidence for facultative responses to the sperm competition environment observed within mammal species. Overall, this review identifies shortcomings in our understanding of the specific mechanisms by which female mammals ‘select’ sperm. More generally, this review demonstrates how, moving forward, mammals will continue to be effective animal models for studying both evolutionary and facultative responses to sperm competition.
This article is part of the theme issue ‘Fifty years of sperm competition’.
Social status and ejaculate composition in the house mouse
Authors: Bayram Helen L. , Franco Catarina , Brownridge Philip , Claydon Amy J. , Koch Natalie , Hurst Jane L. , Beynon Robert J. , Stockley Paula 
Published: October 2020

Sperm competition theory predicts that males should tailor ejaculates according to their social status. Here, we test this in a model vertebrate, the house mouse (Mus musculus domesticus), combining experimental data with a quantitative proteomics analysis of seminal fluid composition. Our analyses reveal that both sperm production and the composition of proteins found in seminal vesicle secretions differ according to social status. Dominant males invested more in ejaculate production overall. Their epididymides contained more sperm than those of subordinate or control males, despite similar testes size between the groups. Dominant males also had larger seminal vesicle glands than subordinate or control males, despite similar body size. However, the seminal vesicle secretions of subordinate males had a significantly higher protein concentration than those of dominant males. Moreover, detailed proteomic analysis revealed subtle but consistent differences in the composition of secreted seminal vesicle proteins according to social status, involving multiple proteins of potential functional significance in sperm competition. These findings have significant implications for understanding the dynamics and outcome of sperm competition, and highlight the importance of social status as a factor influencing both sperm and seminal fluid investment strategies.This article is part of the theme issue ‘Fifty years of sperm competition’.
Anxiety Levels among Healthcare Professionals during Covid-19 Pandemic: A Multifactorial Study
Authors: Malik Arif , Hafeez Muhammad Mansoor , Waquar Sulayman , Rana Muhammad Asim , Alam Rabail 
Published: October 2020

AbstractThe current study focuses on psychological stress level among doctors, estimated by calculating anxiety score. For the assessment of anxiety levels, the GAD-7 scale was used. Chi-Square test and Odd ratios were calculated among the exposed and not exposed groups involved in the management of COVID-19 patients. Results revealed increased anxiety levels in the exposed group. Besides, the availability of personal protective equipment’s and stress from the family to quit the job were the substantial contributing factors that increased anxiety. Based on the results, it is proposed that the concern administrative authorities should consider these findings to facilitate medical healthcare professionals.
White blood cells and severe COVID-19: a Mendelian randomization study
Authors: Sun Yitang , Zhou Jingqi , Ye Kaixiong 
Published: October 2020

AbstractIncreasing evidence shows that white blood cells are associated with the risk of coronavirus disease 2019 (COVID-19), but the direction and causality of this association are not clear. To evaluate the causal associations between various white blood cell traits and the COVID-19 susceptibility and severity, we conducted two-sample bidirectional Mendelian Randomization (MR) analyses with summary statistics from the largest and most recent genome-wide association studies. Our MR results indicated causal protective effects of higher basophil count, basophil percentage of white blood cells, and myeloid white blood cell count on severe COVID-19, with odds ratios (OR) per standard deviation increment of 0.75 (95% CI: 0.60-0.95), 0.70 (95% CI: 0.54-0.92), and 0.85 (95% CI: 0.73-0.98), respectively. Neither COVID-19 severity nor susceptibility was associated with white blood cell traits in our reverse MR results. Genetically predicted high basophil count, basophil percentage of white blood cells, and myeloid white blood cell count are associated with a lower risk of developing severe COVID-19. Individuals with a lower genetic capacity for basophils are likely at risk, while enhancing the production of basophils may be an effective therapeutic strategy.
Modelling SARS-CoV-2 transmission in a UK university setting
Authors: Hill Edward M. , Atkins Benjamin D. , Keeling Matt J. , Tildesley Michael J. , Dyson Louise 
Published: October 2020

AbstractAround 40% of school leavers in the UK attend university and individual universities generally host thousands of students each academic year. Bringing together these student communities during the COVID-19 pandemic may require strong interventions to control transmission. Prior modelling analyses of SARS-CoV-2 transmission within universities using compartmental modelling approaches suggest that outbreaks are almost inevitable.We constructed a network-based model to capture the interactions of a student population in different settings (housing, social and study). For a single academic term of a representative campus-based university, we ran a susceptible-latent-infectious-recovered type epidemic process, parameterised according to available estimates for SARS-CoV-2. We investigated the impact of: adherence to (or effectiveness of) isolation and test and trace measures; room isolation of symptomatic students; and supplementary mass testing.With all adhering to test, trace and isolation measures, we found that 22% (7% - 41%) of the student population could be infected during the autumn term, compared to 69% (56% - 76%) when assuming zero adherence to such measures. Irrespective of the adherence to isolation measures, on average a higher proportion of students resident on-campus became infected compared to students resident off-campus. Room isolation generated minimal benefits. Regular mass testing, together with high adherence to isolation and test and trace measures, could substantially reduce the proportion infected during the term compared to having no testing.Our findings suggest SARS-CoV-2 may readily transmit in a university setting if there is limited ad-herence to nonpharmaceutical interventions and/or there are delays in receiving test results. Following isolation guidance and effective contact tracing curbed transmission and reduced the expected time an adhering student would spend in isolation.
COVID-19 in a Rural Health System in New York – Case Series and an Approach to Management
Authors: Kedar Eyal , Scott Regina , Soule Daniel , Lovelett Carly , Tower Kyle , Broughal Kylie , Jaremczuk Daniel , Mohaddes Sara , Rainey-Spence Imre , Atkinson Timothy 
Published: October 2020

AbstractBackgroundMany rural hospitals and health systems in the U.S. lack sufficient resources to treat COVID-19. We developed a system for managing inpatient COVID-19 hospital admissions in St. Lawrence County, an underserved rural county which is the largest county in New York State.MethodsWe used a hub and spoke system to route COVID-19 patients in the St. Lawrence Health System to its flagship hospital. We assembled a small clinical team to manage admitted COVID-19 patients and to stay abreast of a quickly changing body of literature and standard of care. We subsequently completed a review of clinical data for patients who were treated by our inpatient COVID-19 treatment team between March 20 and May 22, 2020.ResultsTwenty COVID-19 patients were identified. Sixteen patients (80%) met NIH criteria for severe or critical disease. One patient died. No patients were transferred to other hospitals.ConclusionsDuring the first two months of the pandemic, we were able to manage hospitalized COVID-19 patients in our rural community. Development of similar treatment models in other rural areas should be considered.
Aging and COVID-19 mortality: A demographic perspective
Authors: Sasson Isaac 
Published: October 2020

AbstractDemographers have emphasized the importance of age in explaining the spread and impact on mortality of COVID-19. However, the relationship between COVID-19 with age should be contextualized in relation to other causes of death. This study set out to compare the age pattern of COVID-19 mortality with other major causes of death and across countries, and to use these regularities to impute age-specific death counts in countries with partial data. Using US vital Statistics, the COVID-19 mortality doubling time in a Gompertz context was compared with 65 major causes of death. COVID-19 fatality and mortality doubling times were similarly compared within and between 27 countries, using harmonized demographic databases of confirmed COVID-19 cases and deaths. Several findings are supported by the empirical evidence. First, COVID-19 mortality increases exponentially with age at a Gompertz rate near the median of aging-related causes of death, as well as pneumonia and influenza. Second, COVID-19 mortality levels are 2.8 to 8.2 times higher than pneumonia and influenza across the adult age range. Third, the relationship between both COVID-19 fatality and mortality with age varies considerably across countries. Fourth, COVID-19 deaths by age are imputed for Israel as a case in point. In conclusion, the increase in COVID-19 mortality with age resembles the population rate of aging. Country differences in the age pattern of COVID-19 fatality and mortality may point to differences in underlying population health, standards of clinical care, and data quality. This study underscores the need to contextualize the age pattern of COVID-19 mortality in relation to other causes of death.
Melatonin is significantly associated with survival of intubated COVID-19 patients
Authors: Ramlall Vijendra , Zucker Jason , Tatonetti Nicholas 
Published: October 2020

AbstractBackgroundRespiratory distress requiring intubation is the most serious complication associated with coronavirus disease 2019 (COVID-19).MethodsIn this retrospective study, we used survival analysis to determine whether or not mortality following intubation was associated with hormone exposure in patients treated at New York Presbyterian/ Columbia University Irving Medical Center. Here, we report the overall hazards ratio for each hormone for exposure before and after intubation for intubated and mechanically ventilated patients.ResultsAmong the 189,987 patients, we identified 948 intubation periods across 791 patients who were diagnosed with COVID-19 or infected with SARS-CoV2 and 3,497 intubation periods across 2,981 patients who were not. Melatonin exposure after intubation was statistically associated with a positive outcome in COVID-19 (demographics and comorbidities adjusted HR: 0.131, 95% CI: 7.76E-02 - 0.223, p-value = 8.19E-14) and non-COVID-19 (demographics and comorbidities adjusted HR: 0.278, 95% CI: 0.142 - 0.542, p-value = 1.72E-04) intubated patients. Additionally, melatonin exposure after intubation was statically associated with a positive outcome in COVID-19 patients (demographics and comorbidities adjusted HR: 0.127, 95% CI: 6.01E-02 - 0.269, p-value = 7.15E-08).ConclusionsMelatonin exposure after intubation is significantly associated with a positive outcome in COVID-19 and non-COVID-19 patients. Additionally, melatonin exposure after intubation is significantly associated with a positive outcome in COVID-19 patients requiring mechanical ventilation. While our models account for many covariates, including clinical history and demographics, it is impossible to rule out confounding or collider biases within our population. Further study into the possible mechanism of this observation is warranted.
Life course air pollution exposure and cognitive decline: modelled historical air pollution data and the Lothian Birth Cohort 1936
Authors: Russ Tom C. , Cherrie Mark P. C. , Dibben Chris , Tomlinson Sam , Reis Stefan , Dragosits Ulrike , Vieno Massimo , Beck Rachel , Carnell Ed , Shortt Niamh K. , Muniz-Terrera Graciela , Redmond Paul , Taylor Adele M. , Clemens Tom , van Tongeren Martie , Agius Raymond M , Starr John M. , Deary Ian J. , Pearce Jamie R. 
Published: October 2020

ABSTRACTBackgroundAir pollution has been consistently linked with dementia and cognitive decline. However, it is unclear whether risk is accumulated through long-term exposure or whether there are sensitive/critical periods. A key barrier to clarifying this relationship is the dearth of historical air pollution data.ObjectiveTo demonstrate the feasibility of modelling historical air pollution data and using them in epidemiological models.MethodsUsing the EMEP4UK atmospheric chemistry transport model, we modelled historical fine particulate matter (PM2.5) concentrations for the years 1935, 1950, 1970, 1980, and 1990 and combined these with contemporary modelled data from 2001 to estimate life course exposure in 572 participants in the Lothian Birth Cohort 1936 with lifetime residential history recorded. Linear regression and latent growth models were constructed using cognitive ability (IQ) measured by the Moray House Test at the ages of 11, 70, 76, and 79 years to explore the effects of historical air pollution exposure. Covariates included sex, IQ at age 11 years, social class, and smoking.ResultsHigher air pollution modelled for 1935 (when participants would have been in utero) was associated with worse change in IQ from age 11-70 years (β=-0.006, SE=0.002, P=0.03) but not cognitive trajectories from age 70-79 years (P>0.05). There was no support for other critical/sensitive periods of exposure or an accumulation of risk (all P>0.05).ConclusionsThe life course paradigm is essential in understanding cognitive decline and this is the first study to examine life course air pollution exposure in relation to cognitive health.