Maternal inheritance of mitochondria creates a sex‐specific selective sieve through which mitochondrial mutations harmful to males but not females accumulate and contribute to sexual differences in ...longevity and disease susceptibility. Because eggs and sperm are under disruptive selection, sperm are predicted to be particularly vulnerable to the genetic load generated by maternal inheritance, yet evidence for mitochondrial involvement in male fertility is limited and controversial. Here, we exploit the coexistence of two divergent mitochondrial haplogroups (A and B2) in a Neotropical arachnid to investigate the role of mitochondria in sperm competition. DNA profiling demonstrated that B2‐carrying males sired more than three times as many offspring in sperm competition experiments than A males, and this B2 competitive advantage cannot be explained by female mitochondrial haplogroup or male nuclear genetic background. RNA‐Seq of testicular tissues implicates differential expression of mitochondrial oxidative phosphorylation (OXPHOS) genes in the B2 competitive advantage, including a 22‐fold upregulation of atp8 in B2 males. Previous comparative genomic analyses have revealed functionally significant amino acid substitutions in differentially expressed genes, indicating that the mitochondrial haplogroups differ not only in expression but also in DNA sequence and protein functioning. However, mitochondrial haplogroup had no effect on sperm number or sperm viability, and, when females were mated to a single male, neither male haplogroup, female haplogroup nor the interaction between male/female haplogroup significantly affected female reproductive success. Our findings therefore suggest that mitochondrial effects on male reproduction may often go undetected in noncompetitive contexts and may prove more important in nature than is currently appreciated.
In central Panamanian populations of the harlequin beetle riding pseudoscorpion, Cordylochernes scorpioides, males carrying highly divergent mitochondrial haplogroups (A and B2) differ extensively in the expression of mtDNA genes in testicular tissue. DNA profiling demonstrates that B2‐carrying males sire more than three times as many offspring in two‐male sperm competition experiments than do A males, and this B2 competitive advantage cannot be explained by female mitochondrial haplogroup or male nuclear genetic background. Despite conferring strong fitness benefits on males, the B2 haplogroup remains rare in central Panamá as a consequence of male inability to transmit mitochondria to offspring (mother's curse).
Principals are critical for disrupting systems that bar racially diverse students from learning opportunities and belonging in schools. Issues of inequity due to systemic racism have been ongoing and ...politically heightened in the United States as the nation navigates racial tensions within school systems. Research on antiracist school leadership has resulted in important, timely, and relevant frameworks for practice and popular strategies and programs, including courageous conversation and restorative justice programs. However, the process of how to practice antiracist leadership remains difficult and elusive in the translation of theory to praxis. Particularly, principals are rarely trained to develop healthy communication styles and effective conflict resolution skills, especially in conversations about racism. Borrowing from the field of counseling, this article details Gottman's Four Horsemen model of conflict and their resolutions at the interpersonal level. This article frames the model within school contexts for principals to practice and empower their communication skills around race when setting antiracist and equitable school agendas. Recognizing the Four Horsemen and practicing the antidotes to conflicts are important skills for principals to effectively engage in difficult, contentious, and often emotional conversations around racism and its impacts on racially diverse students. Recommendations for principals and preparation programs are provided.
Preterm birth (< 37 weeks gestation) complications are the leading cause of neonatal mortality. Early-warning scores (EWS) are charts where vital signs (e.g., temperature, heart rate, respiratory ...rate) are recorded, triggering action. To evaluate whether a neonatal EWS improves clinical outcomes in low-middle income countries, a randomised trial is needed. Determining whether the use of a neonatal EWS is feasible and acceptable in newborn units, is a prerequisite to conducting a trial. We implemented a neonatal EWS in three newborn units in Kenya. Staff were asked to record infants' vital signs on the EWS during the study, triggering additional interventions as per existing local guidelines. No other aspects of care were altered. Feasibility criteria were pre-specified. We also interviewed health professionals (n = 28) and parents/family members (n = 42) to hear their opinions of the EWS. Data were collected on 465 preterm and/or low birthweight (< 2.5 kg) infants. In addition to qualitative study participants, 45 health professionals in participating hospitals also completed an online survey to share their views on the EWS. 94% of infants had the EWS completed at least once during their newborn unit admission. EWS completion was highest on the day of admission (93%). Completion rates were similar across shifts. 15% of vital signs triggered escalation to a more senior member of staff. Health professionals reported liking the EWS, though recognised the biggest barrier to implementation was poor staffing. Newborn unit infant to staff ratios varied between 10 and 53 staff per 1 infant, depending upon time of shift and staff type. A randomised trial of neonatal EWS in Kenya is possible and acceptable, though adaptations are required to the form before implementation.
Although climate change models predict relatively modest increases in temperature in the tropics by the end of the century, recent analyses identify tropical ectotherms as the organisms most at risk ...from climate warming. Because metabolic rate in ectotherms increases exponentially with temperature, even a small rise in temperature poses a physiological threat to tropical ectotherms inhabiting an already hot environment. If correct, the metabolic theory of climate warming has profound implications for global biodiversity, since tropical insects and arachnids constitute the vast majority of animal species. Predicting how climate change will translate into fitness consequences for tropical arthropods requires an understanding of the effects of temperature increase on the entire life history of the species. Here, in a comprehensive case study of the fitness consequences of the projected temperature increase for the tropics, we conducted a split‐brood experiment on the neotropical pseudoscorpion, Cordylochernes scorpioides, in which 792 offspring from 33 females were randomly assigned at birth to control‐ and high‐temperature treatments for rearing through the adult stage. The diurnally varying, control treatment temperature was determined from long‐term, average daily temperature minima and maxima in the pseudoscorpion's native habitat. In the high temperature treatment, increasing temperature by the 3.5 °C predicted for the tropics significantly reduced survival and accelerated development at the cost of reduced adult size and a dramatic decrease in level of sexual dimorphism. The most striking effects, however, involved reproductive traits. Reared at high temperature, males produced 45% as many sperm as control males, and females failed to reproduce. Sequencing of the mitochondrial ND2 gene revealed two highly divergent haplogroups that differed substantially in developmental rate and survivorship but not in reproductive response to high temperature. Our findings suggest that reproduction may be the Achilles’ heel of tropical ectotherms, as climate warming subjects them to an increasingly adverse thermal environment.
Recent theory suggests that global warming may be catastrophic for tropical ectotherms. Although most studies addressing temperature effects in ectotherms utilize constant temperatures, Jensen's ...inequality and thermal stress considerations predict that this approach will underestimate warming effects on species experiencing daily temperature fluctuations in nature. Here, we tested this prediction in a neotropical pseudoscorpion. Nymphs were reared in control and high-temperature treatments under a constant daily temperature regime, and results compared to a companion fluctuating-temperature study. At constant temperature, pseudoscorpions outperformed their fluctuating-temperature counterparts. Individuals were larger, developed faster, and males produced more sperm, and females more embryos. The greatest impact of temperature regime involved short-term, adult exposure, with constant temperature mitigating high-temperature effects on reproductive traits. Our findings demonstrate the importance of realistic temperature regimes in climate warming studies, and suggest that exploitation of microhabitats that dampen temperature oscillations may be critical in avoiding extinction as tropical climates warm.
Recent theory suggests that tropical terrestrial arthropods are at significant risk from climate warming. Metabolic rate in such ectothermic species increases exponentially with environmental ...temperature, and a small temperature increase in a hot environment can therefore have a greater physiological impact than a large temperature increase in a cool environment. In two recent studies of the neotropical pseudoscorpion,
, simulated climate warming significantly decreased survival, body size and level of sexual dimorphism. However, these effects were minor compared with catastrophic consequences for male fertility and female fecundity, identifying reproduction as the life stage most vulnerable to climate warming. Here, we examine the effects of chronic high-temperature exposure on epigenetic regulation in
in the context of naturally occurring variation in mitochondrial DNA. Epigenetic mechanisms, including DNA methylation, histone modifications and small non-coding RNA (sncRNA) expression, are particularly sensitive to environmental factors such as temperature, which can induce changes in epigenetic states and phenotypes that may be heritable across generations. Our results indicate that exposure of male pseudoscorpions to elevated temperature significantly altered the expression of >60 sncRNAs in testicular tissue, specifically microRNAs and piwi-interacting RNAs. Mitochondrial haplogroup was also a significant factor influencing both sncRNAs and mitochondrial gene expression. These findings demonstrate that chronic heat stress causes changes in epigenetic profiles that may account for reproductive dysfunction in
males. Moreover, through its effects on epigenetic regulation, mitochondrial DNA polymorphism may provide the potential for an adaptive evolutionary response to climate warming.
The purpose of this conceptual paper is to highlight the impacts of psychological and biological health on the principalship, particularly as it relates to sleep. Job-related stress, heavy workloads, ...and unpredictable work schedules can impact principals’ mental health, diet, and consumptive behaviors, which can disrupt the much-needed restorative sleep for healthy cognition, physiological functioning, and efficacious leadership. We turn the field's attention towards the importance of quality sleep and how it impacts personal health and occupational performance. We provide a robust interdisciplinary review of literature on precursors and outcomes of poor sleep quality as it pertains to school leaders both personally and professionally. Empirical recommendations for improving sleep quality along with recommendations for preparation programs and the field of educational leadership are discussed.
While the plight of polar bears in a rapidly warming world is much publicized, recent theory suggests that the organisms likely to be most at risk from rising temperatures are terrestrial arthropods ...and reptiles inhabiting the tropics. Metabolic rate in such ectothermic species increases exponentially with ambient temperature, and a small temperature increase in a warm environment therefore has a much larger physiological impact than a comparable temperature increase in a cool environment. In a recently published study on the neotropical pseudoscorpion, Cordylochernes scorpioides, simulated climate warming significantly decreased survival, average values for morphological traits, and level of sexual dimorphism. However, these effects were minor compared to catastrophic consequences for male fertility and female fecundity, identifying reproduction as the life history stage most vulnerable to climate warming. Still to be investigated, however, was the potential for epigenetically and genetically based responses to elevated temperature. Here, I examined the effects of chronic high-temperature exposure on epigenetic regulation in C. scorpioides in the context of naturally occurring variation in mitochondrial DNA. Epigenetic mechanisms, including DNA methylation, histone modification, and small non- coding RNA (sncRNA) expression, are particularly sensitive to environmental factors such as temperature, which can induce physiological stress and bring about changes in epigenetic states and phenotypes that may be heritable across generations. My results indicate that exposure of male pseudoscorpions to elevated temperature significantly altered the expression of sncRNAs, specifically microRNAs and piwi-interacting RNAs, in testicular tissue. Mitochondrial haplogroup was also a significant factor influencing both sncRNAs and mitochondrial gene expression. These findings demonstrate that chronic heat stress alters epigenetic profiles that may at least partially account for reduced reproductive function in male C. scorpioides. Moreover, through its effects on epigenetic regulation, mitochondrial DNA polymorphism may provide the potential for an adaptive evolutionary response to climate warming. Since tropical terrestrial arthropods constitute the vast majority of animal species, the results of this study have important implications for understanding the consequences of climate change for global biodiversity.
Malaria elimination strategies require surveillance of the parasite population for genetic changes that demand a public health response, such as new forms of drug resistance. Here we describe methods ...for the large-scale analysis of genetic variation in Plasmodium falciparum by deep sequencing of parasite DNA obtained from the blood of patients with malaria, either directly or after short-term culture. Analysis of 86,158 exonic single nucleotide polymorphisms that passed genotyping quality control in 227 samples from Africa, Asia and Oceania provides genome-wide estimates of allele frequency distribution, population structure and linkage disequilibrium. By comparing the genetic diversity of individual infections with that of the local parasite population, we derive a metric of within-host diversity that is related to the level of inbreeding in the population. An open-access web application has been established for the exploration of regional differences in allele frequency and of highly differentiated loci in the P. falciparum genome.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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