Most animals establish long-term symbiotic associations with bacteria that are critical for normal host physiology. The symbiosis that forms between the Hawaiian squid Euprymna scolopes and the ...bioluminescent bacterium Vibrio fischeri serves as an important model system for investigating the molecular mechanisms that promote animal-bacterial symbioses. E. scolopes hatch from their eggs uncolonized, which has led to the development of squid-colonization assays that are based on introducing culture-grown V. fischeri cells to freshly hatched juvenile squid. Recent studies have revealed that strains often exhibit large differences in how they establish symbiosis. Therefore, we sought to develop a simplified and reproducible protocol that permits researchers to determine appropriate inoculum levels and provides a platform to standardize the assay across different laboratories. In our protocol, we adapt a method commonly used for evaluating the infectivity of pathogens to quantify the symbiotic capacity of V. fischeri strains. The resulting metric, the symbiotic dose-50 (SD50), estimates the inoculum level that is necessary for a specific V. fischeri strain to establish a light-emitting symbiosis. Relative to other protocols, our method requires 2-5-fold fewer animals. Furthermore, the power analysis presented here suggests that the protocol can detect up to a 3-fold change in the SD50 between different strains.
Each spring, migratory herbivores around the world track or ‘surf’ green waves of newly emergent vegetation to distant summer or wet‐season ranges. This foraging tactic may help explain the great ...abundance of migratory herbivores on many seasonal landscapes. However, the underlying fitness benefits of this life‐history strategy remain poorly understood. A fundamental prediction of the green‐wave hypothesis is that migratory herbivores obtain fitness benefits from surfing waves of newly emergent vegetation more closely than their resident counterparts. Here we evaluate whether this behavior increases body‐fat levels – a critically important correlate of reproduction and survival for most ungulates – in elk Cervus elaphus of the Greater Yellowstone Ecosystem. Using satellite imagery and GPS tracking data, we found evidence that migrants (n = 23) indeed surfed the green wave, occupying sites 12.7 days closer to peak green‐up than residents (n = 16). Importantly, individual variation in surfing may help account for up to 6 kg of variation in autumn body‐fat levels. Our findings point to a pathway for anthropogenic changes to the green wave (e.g. climate change) or migrants’ ability to surf it (e.g. development) to impact migratory populations. To explore this possibility, we evaluated potential population‐level consequences of constrained surfing with a heuristic model. If green‐wave surfing deteriorates by 5–15 days from observed, our model predicts up to a 20% decrease in pregnancy rates, a 2.5% decrease in population growth, and a 30% decrease in abundance over 50 years. By linking green‐wave surfing to fitness and illustrating potential effects on population growth, our study provides new insights into the evolution of migratory behavior and the prospects for the persistence of migratory ungulate populations in a changing world.
Migration is a striking behavioral strategy by which many animals enhance resource acquisition while reducing predation risk. Historically, the demographic benefits of such movements made migration ...common, but in many taxa the phenomenon is considered globally threatened. Here we describe a long-term decline in the productivity of elk (
Cervus elaphus
) that migrate through intact wilderness areas to protected summer ranges inside Yellowstone National Park, USA. We attribute this decline to a long-term reduction in the demographic benefits that ungulates typically gain from migration. Among migratory elk, we observed a 21-year, 70% reduction in recruitment and a 4-year, 19% depression in their pregnancy rate largely caused by infrequent reproduction of females that were young or lactating. In contrast, among resident elk, we have recently observed increasing recruitment and a high rate of pregnancy. Landscape-level changes in habitat quality and predation appear to be responsible for the declining productivity of Yellowstone migrants. From 1989 to 2009, migratory elk experienced an increasing rate and shorter duration of green-up coincident with warmer spring-summer temperatures and reduced spring precipitation, also consistent with observations of an unusually severe drought in the region. Migrants are also now exposed to four times as many grizzly bears (
Ursus arctos
) and wolves (
Canis lupus
) as resident elk. Both of these restored predators consume migratory elk calves at high rates in the Yellowstone wilderness but are maintained at low densities via lethal management and human disturbance in the year-round habitats of resident elk. Our findings suggest that large-carnivore recovery and drought, operating simultaneously along an elevation gradient, have disproportionately influenced the demography of migratory elk. Many migratory animals travel large geographic distances between their seasonal ranges. Changes in land use and climate that disparately influence such seasonal ranges may alter the ecological basis of migratory behavior, representing an important challenge for, and a powerful lens into, the ecology and conservation of migratory taxa.
Recent studies have documented worrisome levels of hesitancy and resistance to the COVID-19 vaccine, including within the adolescent population. In this study, we examined attitudinal (perceived ...severity of COVID-19, vaccine-related concerns) and interpersonal (parent and peer norms) antecedents of adolescents' intentions to receive the COVID-19 vaccine.
Participants were 916 adolescents (aged 12–17 years) from across the United States (47.3% male) representing diverse ethnic and socioeconomic backgrounds (26% African-American, 22% Hispanic/Latinx, 35% white, 7% Asian American). They completed a survey on their experiences and attitudes surrounding COVID-19 and the COVID-19 vaccine.
Parent and peer norms were distinct predictors of adolescent willingness to receive the vaccine. These norms were associated with vaccine intentions directly and indirectly through adolescents' beliefs about the vaccine's safety, efficacy, and necessity. Parent norms in particular displayed large effect sizes and explained considerable variance in adolescents' vaccine intentions.
Parents and friends—who figure as adolescents' most salient interpersonal relationships—are key leveraging points in promoting adolescents' uptake of the COVID-19 vaccine. Norm interventions and family-based interventions may be successful in this regard.
The ability to perform hematopoietic cell transplant across major histocompatibility complex barriers can dramatically increase the availability of donors and allow more patients across the world to ...pursue curative transplant procedures for underlying hematologic disorders. Early attempts at haploidentical transplantation using broadly reactive T-cell depletion approaches were compromised by graft rejection, graft-versus-host disease and prolonged immune deficiency. The evolution of haploidentical transplantation focused on expanding transplanted hematopoietic progenitors as well as using less broadly reactive T-cell depletion. Significant outcome improvements were identified with technology advances allowing selective depletion of donor allospecific T cells, initially ex-vivo with evolution to its current in-vivo approach with the infusion of the highly immunosuppressive chemotherapy agent, cyclophosphamide after transplantation procedure. Current approaches are facile and portable, allowing expansion of allogeneic hematopoietic cell transplantation for patients across the world, including previously underserved populations.
Populations of woodland caribou (Rangifer tarandus caribou) are declining throughout their range and many are at risk of extirpation, yet the role of nutrition in these declines remains poorly ...understood, in part owing to a lack of information about available nutritional resources during summer. We quantified rates of intake of digestible protein and digestible energy by tame caribou foraging in temporary enclosures in the predominant plant communities of northeastern British Columbia, Canada, during summer–autumn and compared intake rates to daily requirements for protein and energy during lactation. We tested hypotheses related to the nutritional adequacy of the environment to support nutritional requirements during lactation (with and without replenishment of body reserves) and simulated scenarios of foraging by caribou in these plant communities to better understand how wild caribou could meet nutritional demands on these landscapes. Nutritional resources varied among plant communities across seasonal, ecological, and successional gradients; digestible energy intake per minute and per day were significantly greater in younger than older forests; dietary digestible energy and per‐minute and daily intake of digestible protein were greater, though not significantly so, in younger than older forests; and dietary digestible protein was greater in older than younger forests, though differences were not significant. Tame caribou were unable to satisfy protein and energy requirements during lactation, even without replenishment of body reserves, at most sites sampled. Further, foraging simulations suggested widespread nutritional inadequacies on ranges of wild caribou. Selection for habitats offering the best nutrition may mitigate some nutritional inadequacies, but given low availability of vegetation communities with high nutritional value, performance (e.g., calf production, growth, replenishment of body fat and protein) of caribou may be depressed at levels of nutrition documented herein. Our results, coupled with recent measurements of body fat of wild caribou in northeastern British Columbia, refute the hypothesis that the nutritional environment available to caribou during summer in northeastern British Columbia is adequate to fully support nutritional demands of lactating caribou, which has implications to productivity of caribou populations, recovery, and conservation.
Nutritional resources available to caribou in northeastern British Columbia, Canada, during summer–autumn 2013–2015 were variable and largely inadequate to support nutritional requirements during lactation and for replenishment of body protein and fat reserves, thereby potentially constraining individual performance with implications to population productivity. Critical habitat designations corresponded poorly with nutritional value of caribou habitats in summer and early autumn.
As powerful computational tools and 'big data' transform the biological sciences, bioinformatics training is becoming necessary to prepare the next generation of life scientists. Furthermore, because ...the tools and resources employed in bioinformatics are constantly evolving, bioinformatics learning materials must be continuously improved. In addition, these learning materials need to move beyond today's typical step-by-step guides to promote deeper conceptual understanding by students. One of the goals of the Network for Integrating Bioinformatics into Life Sciences Education (NIBSLE) is to create, curate, disseminate, and assess appropriate open-access bioinformatics learning resources. Here we describe the evolution, integration, and assessment of a learning resource that explores essential concepts of biological sequence similarity. Pre/post student assessment data from diverse life science courses show significant learning gains. These results indicate that the learning resource is a beneficial educational product for the integration of bioinformatics across curricula.
Tillage and fertilization are common practices used to enhance soil fertility and increase yield. Changes in soil edaphic properties associated with different tillage and fertility regimes have been ...widely examined, yet, the microbially mediated pathways and ecological niches involved in enhancing soil fertility are poorly understood. The effects of long-term conventional tillage and no-till in parallel with three fertility treatments (No fertilization, N-only, and NPK) on soil microbial communities were investigated in a long-term field study that was established in the 1970's. Here, we used high-throughput sequencing of bacterial, fungal and oomycetes markers, followed by community-level functional and ecological assembly to discern principles governing tillage and fertility practices' influence on associated soil microbiomes. Both tillage and fertilizer significantly altered microbial community structure, but the tillage effect was more prominent than the fertilizer effect. Tillage significantly affected bacteria, fungi, fusaria, and oomycete beta-diversity, whereas fertilizer only affected bacteria and fungi beta-diversity. In our study different tillage and fertilizer regimes favored specific networks of metabolic pathways and distinct ecological guilds. No-till selected for beneficial microbes that translocate nutrients and resources and protect the host against pathogens. Notably, ecological guilds featuring arbuscular mycorrhizae, mycoparasites, and nematophagous fungi were favored in no-till soils, while fungal saprotrophs and plant pathogens dominated in tilled soils. Conventional till and fertilizer management shifted the communities toward fast growing competitors. Copiotrophic bacteria and fusarium species were favored under conventional tillage and in the presence of fertilizers. The analysis of the metagenomes revealed a higher abundance of predicted pathways associated with energy metabolism, translation, metabolism of cofactors and vitamins, glycan biosynthesis and nucleotide metabolism in no-till. Furthermore, no specific pathways were found to be enriched under the investigated fertilization regimes. Understanding how tillage and fertilizer management shift microbial diversity, structure and ecological niches, such as presented here, can assist with designing farming systems that can maintain high crop yield, while reducing soil erosion and nutrient losses.
Gender discrimination is a common experience for adolescent girls and has implications for their mental health and identity development. Guided by Phenomenological Variant of Ecological Systems ...Theory (PVEST; Spencer et al.
1997
), this study examined the longitudinal and bidirectional associations between adolescent girls’ experiences of gender discrimination, their internalizing symptoms, and gender identity. The sample was 161 adolescent girls (ages 14–17;
M
age
= 15.90) from across the United States (51% White; 17% African American, 11% Hispanic/Latina) who participated in a short-term longitudinal study of adolescent development. The results showed a reciprocal, longitudinal association between discrimination and internalizing symptoms. Discrimination also predicted longitudinal declines in gender identity, which was explained indirectly through internalizing symptoms. The findings implicate gender discrimination as a distinct risk factor during girls’ developmental years, and underscore the importance of helping girls learn adaptive responses to sexism, while also reducing actual occurrence and exposure.
PDF
