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1.
Ecol Evol ; 14(9): e70044, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39279793

RESUMEN

The Karner blue butterfly, Plebejus (Lycaeides) samuelis, is an endangered North American climate change-vulnerable species that has undergone substantial historical habitat loss and population decline. To better understand the species' genetic status and support Karner blue conservation, we sampled 116 individuals from 22 localities across the species' geographical range in Wisconsin (WI), Michigan (MI), Indiana (IN), and New York (NY). Using genomic analysis, we found that these samples were divided into three major geographic groups, NY, WI, and MI-IN, with populations in WI and MI-IN each further divided into three subgroups. A high level of inbreeding was revealed by inbreeding coefficients above 10% in almost all populations in our study. However, strong correlation between F ST and geographical distance suggested that genetic divergence between populations increases with distance, such that introducing individuals from more distant populations may be a useful strategy for increasing population-level diversity and preserving the species. We also found that Karner blue populations had lower genetic diversity than closely related species and had more alleles that were present only at low frequencies (<5%) in other species. Some of these alleles may negatively impact individual fitness and may have become prevalent in Karner blue populations due to inbreeding. Finally, analysis of these possibly deleterious alleles in the context of predicted three-dimensional structures of proteins revealed potential molecular mechanisms behind population declines, providing insights for conservation. This rich new range-wide understanding of the species' population genomic structure can contextualize past extirpations and help conserve and even enhance Karner blue genetic diversity.

2.
ACS Cent Sci ; 10(7): 1357-1370, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-39071060

RESUMEN

Tailored enzymes are crucial for the transition to a sustainable bioeconomy. However, enzyme engineering is laborious and failure-prone due to its reliance on serendipity. The efficiency and success rates of engineering campaigns may be improved by applying machine learning to map the sequence-activity landscape based on small experimental data sets. Yet, it often proves challenging to reliably model large sequence spaces while keeping the experimental effort tractable. To address this challenge, we present an integrated pipeline combining large-scale screening with active machine learning, which we applied to engineer an artificial metalloenzyme (ArM) catalyzing a new-to-nature hydroamination reaction. Combining lab automation and next-generation sequencing, we acquired sequence-activity data for several thousand ArM variants. We then used Gaussian process regression to model the activity landscape and guide further screening rounds. Critical characteristics of our pipeline include the cost-effective generation of information-rich data sets, the integration of an explorative round to improve the model's performance, and the inclusion of experimental noise. Our approach led to an order-of-magnitude boost in the hit rate while making efficient use of experimental resources. Search strategies like this should find broad utility in enzyme engineering and accelerate the development of novel biocatalysts.

3.
Int J Exerc Sci ; 17(4): 172-182, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38665851

RESUMEN

The Army Combat Fitness Test (ACFT) is used to evaluate the fitness level of potential Cadets for military readiness. The purpose of this study was to evaluate the effectiveness of the exercise training program implemented by an Army Reserve Officers' Training Corps (ROTC) program to gauge the performance metrics of the ACFT. METHODS: Twenty-six student Cadets of the ROTC at the University of Alabama at Birmingham (UAB) program participated in the study. Over an 8-month period, the ROTC Cadets trained on campus three days per week. Training was performed in a circuit training format and each participant cycled through each of the four training stations (Strength, Conditioning, Core, and Endurance) for 15 minutes each session (for a total training time of 60 minutes). Each Cadet had body mass and body composition assessed as well as each component of the ACFT [maximum dead lift (MDL), standing power throw (SPT), hand release push-up (HRP), sprint-drag-carry (SDC), leg tuck/plank (LTK/PLK), and 2-mile run (2MR)]. Each variable was evaluated at three time points (pre-, mid-, and post-training program). RESULTS: There was a significant difference in the 2MR score between time points [F(2,50) = 4.530, p = .016, η2 = 0.153] with a significant difference between time point at pre- and post-training (p = .02). No other variables displayed a significant change: body mass (p = .741), body fat percentage (p = .238), MDL (p = .061), SPT (p = .308), HRP (p = .126), SDC (p = 0.132), LTK/PLK (p = 0.583). CONCLUSION: The results of this study suggest that the short-term training program used improves 2MR, but not other components of the ACFT over the course of an academic year.

4.
PLoS One ; 18(8): e0288812, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37556450

RESUMEN

BACKGROUND: The climate crisis is the greatest public health threat of the 21st century. Excessive heat is responsible for more deaths than any other extreme weather event, and the frequency, intensity, and duration of extreme heat events are increasing globally due to climate change. Exposure to excessive heat can result in heat related illnesses (HRIs) and long-term poor health outcomes. Physical exertion, sudden exposure to excessive heat, and the lack of physical or behavioral adaptation resources are all associated with greater HRI risk, which is expected to increase for visitors to Grand Canyon National Park (GCNP) and other public lands as climate change worsens. OBJECTIVES: Our objectives were to understand 1) the relationship between weather and HRI in GCNP visitors, 2) how future HRI rates may change, and 3) how land management agencies can update risk mitigation strategies to match changing risk and better manage an increased HRI burden. METHODS: We utilized previously published data on HRI in GCNP visitors, and records of daily visitation, temperatures, and maximum and minimum daily humidity from the same study period to develop a model estimate for HRI risk. We then used future climate projections from the World Climate Research Programme's Coupled Model Intercomparison Project phase 5 multi-model dataset to model future HRI risk under different climate scenarios. RESULTS: The incidence of HRI was significantly associated with maximum daily temperature and minimum relative humidity, and was more common in the shoulder season months. We estimated that HRI will increase 29%-137% over 2004-2009 levels through 2100, assuming no change in visitation. DISCUSSION: Climate change will continue to increase HRI risk for GCNP visitors and poses risks to public land managers' mission to provide for safe recreation experiences for the benefit of this and future generations in places like GCNP. Excessive risk during the shoulder season months presents an opportunity to increase preventative search and rescue and education efforts to mitigate increased risk.


Asunto(s)
Calor Extremo , Trastornos de Estrés por Calor , Humanos , Calor , Parques Recreativos , Temperatura , Cambio Climático
5.
Ecol Appl ; 33(6): e2901, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37334723

RESUMEN

In fire-prone ecosystems, knowledge of vegetation-fire-climate relationships and the history of fire suppression and Indigenous cultural burning can inform discussions of how to use fire as a management tool, particularly as climate continues to change rapidly. On Wiisaakodewan-minis/Stockton Island in the Apostle Islands National Lakeshore of Wisconsin, USA, structural changes in a pine-dominated natural area containing a globally rare barrens community occurred after the cessation of cultural burning by the Indigenous Ojibwe people and the imposition of fire-suppression policies, leading to questions about the historical role of fire in this culturally and ecologically important area. To help understand better the ecological context needed to steward these pine forest and barrens communities, we developed palaeoecological records of vegetation, fire, and hydrological change using pollen, charcoal, and testate amoebae preserved in peat and sediment cores collected from bog and lagoon sediments within the pine-dominated landscape. Results indicated that fire has been an integral part of Stockton Island ecology for at least 6000 years. Logging in the early 1900s led to persistent changes in island vegetation, and post-logging fires of the 1920s and 1930s were anomalous in the context of the past millennium, likely reflecting more severe and/or extensive burning than in the past. Before that, the composition and structure of pine forest and barrens had changed little, perhaps due to regular low-severity surface fires, which may have occurred with a frequency consistent with Indigenous oral histories (~4-8 years). Higher severity fire episodes, indicated by large charcoal peaks above background levels in the records, occurred predominantly during droughts, suggesting that more frequent or more intense droughts in the future may increase fire frequency and severity. The persistence of pine forest and barrens vegetation through past periods of climatic change indicates considerable ecological resistance and resilience. Future persistence in the face of climate changes outside this historical range of variability may depend in part on returning fire to these systems.


Asunto(s)
Incendios , Pinus , Humanos , Ecosistema , Carbón Orgánico , Bosques , Wisconsin , Árboles
6.
Nat Biotechnol ; 41(12): 1765-1775, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37156914

RESUMEN

Organoids generated from human pluripotent stem cells provide experimental systems to study development and disease, but quantitative measurements across different spatial scales and molecular modalities are lacking. In this study, we generated multiplexed protein maps over a retinal organoid time course and primary adult human retinal tissue. We developed a toolkit to visualize progenitor and neuron location, the spatial arrangements of extracellular and subcellular components and global patterning in each organoid and primary tissue. In addition, we generated a single-cell transcriptome and chromatin accessibility timecourse dataset and inferred a gene regulatory network underlying organoid development. We integrated genomic data with spatially segmented nuclei into a multimodal atlas to explore organoid patterning and retinal ganglion cell (RGC) spatial neighborhoods, highlighting pathways involved in RGC cell death and showing that mosaic genetic perturbations in retinal organoids provide insight into cell fate regulation.


Asunto(s)
Células Madre Pluripotentes , Retina , Humanos , Células Ganglionares de la Retina/metabolismo , Transcriptoma/genética , Organoides , Diferenciación Celular/genética
7.
PLoS Comput Biol ; 18(5): e1010082, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35588132

RESUMEN

Understanding the inherited nature of how biological processes dynamically change over time and exhibit intra- and inter-individual variability, due to the different responses to environmental stimuli and when interacting with other processes, has been a major focus of systems biology. The rise of single-cell fluorescent microscopy has enabled the study of those phenomena. The analysis of single-cell data with mechanistic models offers an invaluable tool to describe dynamic cellular processes and to rationalise cell-to-cell variability within the population. However, extracting mechanistic information from single-cell data has proven difficult. This requires statistical methods to infer unknown model parameters from dynamic, multi-individual data accounting for heterogeneity caused by both intrinsic (e.g. variations in chemical reactions) and extrinsic (e.g. variability in protein concentrations) noise. Although several inference methods exist, the availability of efficient, general and accessible methods that facilitate modelling of single-cell data, remains lacking. Here we present a scalable and flexible framework for Bayesian inference in state-space mixed-effects single-cell models with stochastic dynamic. Our approach infers model parameters when intrinsic noise is modelled by either exact or approximate stochastic simulators, and when extrinsic noise is modelled by either time-varying, or time-constant parameters that vary between cells. We demonstrate the relevance of our approach by studying how cell-to-cell variation in carbon source utilisation affects heterogeneity in the budding yeast Saccharomyces cerevisiae SNF1 nutrient sensing pathway. We identify hexokinase activity as a source of extrinsic noise and deduce that sugar availability dictates cell-to-cell variability.


Asunto(s)
Fenómenos Fisiológicos Celulares , Biología de Sistemas , Teorema de Bayes , Modelos Biológicos , Saccharomyces cerevisiae , Procesos Estocásticos , Biología de Sistemas/métodos
8.
Conserv Biol ; 36(2): e13838, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-34622995

RESUMEN

Adaptive capacity (AC)-the ability of a species to cope with or accommodate climate change-is a critical determinant of species vulnerability. Using information on species' AC in conservation planning is key to ensuring successful outcomes. We identified connections between a list of species' attributes (e.g., traits, population metrics, and behaviors) that were recently proposed for assessing species' AC and management actions that may enhance AC for species at risk of extinction. Management actions were identified based on evidence from the literature, a review of actions used in other climate adaptation guidance, and our collective experience in diverse fields of global-change ecology and climate adaptation. Selected management actions support the general AC pathways of persist in place or shift in space, in response to contemporary climate change. Some actions, such as genetic manipulations, can be used to directly alter the ability of species to cope with climate change, whereas other actions can indirectly enhance AC by addressing ecological or anthropogenic constraints on the expression of a species' innate abilities to adapt. Ours is the first synthesis of potential management actions directly linked to AC. Focusing on AC attributes helps improve understanding of how and why aspects of climate are affecting organisms, as well as the mechanisms by which management interventions affect a species' AC and climate change vulnerability. Adaptive-capacity-informed climate adaptation is needed to build connections among the causes of vulnerability, AC, and proposed management actions that can facilitate AC and reduce vulnerability in support of evolving conservation paradigms.


Aplicación de Evaluaciones de la Capacidad Adaptativa para Informar la Gestión de Recursos Naturales en un Clima Cambiante Resumen La capacidad adaptativa (CA) - la habilidad que tiene una especie para sobrellevar o acomodarse al cambio climático - es una determinante crítica de la vulnerabilidad de una especie. El uso de la información sobre la CA de una especie dentro de la planeación de la conservación es de suma importancia para asegurar resultados exitosos. Identificamos las conexiones entre una lista de atributos de las especies (p. ej.: características, métricas poblacionales, comportamientos) que fueron propuestos recientemente para la evaluación de la CA de las especies y las acciones de gestión que pueden mejorar la CA para las especies que se encuentran en riesgo de extinción. Las acciones de gestión fueron identificadas con base en la evidencia de la literatura, una revisión de acciones usadas en otras guías de adaptación climática y nuestra experiencia colectiva en diferentes campos de la ecología del cambio global y la adaptación climática. Ciertas acciones de gestión respaldan las vías generales de CA de persistir en el lugar o cambiar en el espacio como respuesta al cambio climático contemporáneo. Algunas acciones, como la manipulación genética, pueden usarse para alterar directamente la habilidad que tienen las especies para sobrellevar el cambio climático, mientras que otras acciones pueden mejorar indirectamente la CA al combatir las restricciones ecológicas o antropogénicas que existen sobre la expresión de las habilidades innatas de una especie para adaptarse. Nuestra síntesis es la primera que aborda acciones potenciales de gestión conectadas directamente con la CA. Enfocarse en los atributos de la CA ayuda a mejorar el conocimiento sobre cómo y por qué los aspectos climáticos están afectando a los organismos, así como los mecanismos mediante los cuales las intervenciones de gestión afectan la CA y la vulnerabilidad al cambio climático de la especie. La adaptación climática orientada por la capacidad adaptativa es necesaria para establecer conexiones entre las causas de la vulnerabilidad, la CA y las acciones de gestión propuestas que pueden facilitar la CA y reducir la vulnerabilidad como apoyo a los paradigmas cambiantes de la conservación.


Asunto(s)
Cambio Climático , Conservación de los Recursos Naturales , Recursos Naturales
9.
Metab Eng ; 69: 98-111, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34767976

RESUMEN

The biosynthesis of short-chain alcohols is a carbon-neutral alternative to petroleum-derived production, but strain screening operations are encumbered by laborious analytics. Here, we built, characterized and applied whole cell biosensors by directed evolution of the transcription factor AlkS for screening microbial strain libraries producing industrially relevant alcohols. A selected AlkS variant was applied for in situ product detection in two screening applications concerning key steps in alcohol production. Further, the biosensor strains enabled the implementation of an automated, robotic platform-based workflow with data clustering, which readily allowed the identification of significantly improved strain variants for isopentanol production.


Asunto(s)
Biocombustibles , Técnicas Biosensibles , Etanol , Ingeniería Metabólica
10.
Evol Appl ; 14(8): 1969-1979, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34429742

RESUMEN

There is an imperative for conservation practitioners to help biodiversity adapt to accelerating environmental change. Evolutionary biologists are well-positioned to inform the development of evidence-based management strategies that support the adaptive capacity of species and ecosystems. Conservation practitioners increasingly accept that management practices must accommodate rapid environmental change, but harbour concerns about how to apply recommended changes to their management contexts. Given the interest from both conservation practitioners and evolutionary biologists in adjusting management practices, we believe there is an opportunity to accelerate the required changes by promoting closer collaboration between these two groups. We highlight how evolutionary biologists can harness lessons from other disciplines about how to foster effective knowledge exchange to make a substantive contribution to the development of effective conservation practices. These lessons include the following: (1) recognizing why practitioners do and do not use scientific evidence; (2) building an evidence base that will influence management decisions; (3) translating theory into a format that conservation practitioners can use to inform management practices; and (4) developing strategies for effective knowledge exchange. Although efforts will be required on both sides, we believe there are rewards for both practitioners and evolutionary biologists, not least of which is fostering practices to help support the long-term persistence of species.

11.
G3 (Bethesda) ; 10(12): 4373-4385, 2020 12 03.
Artículo en Inglés | MEDLINE | ID: mdl-33023973

RESUMEN

Time-lapse imaging of live cells using multiple fluorescent reporters is an essential tool to study molecular processes in single cells. However, exposure to even moderate doses of visible excitation light can disturb cellular physiology and alter the quantitative behavior of the cells under study. Here, we set out to develop guidelines to avoid the confounding effects of excitation light in multi-color long-term imaging. We use widefield fluorescence microscopy to measure the effect of the administered excitation light on growth rate (here called photomorbidity) in yeast. We find that photomorbidity is determined by the cumulative light dose at each wavelength, but independent of the way excitation light is applied. Importantly, photomorbidity possesses a threshold light dose below which no effect is detectable (NOEL). We found, that the suitability of fluorescent proteins for live-cell imaging at the respective excitation light NOEL is equally determined by the cellular autofluorescence and the fluorescent protein brightness. Last, we show that photomorbidity of multiple wavelengths is additive and imaging conditions absent of photomorbidity can be predicted. Our findings enable researchers to find imaging conditions with minimal impact on physiology and can provide framework for how to approach photomorbidity in other organisms.


Asunto(s)
Microscopía Fluorescente , Saccharomyces cerevisiae , Schizosaccharomyces , Color , Fluorescencia , Imagen Óptica , Saccharomyces cerevisiae/genética
12.
Mol Genet Genomics ; 295(6): 1489-1500, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32948893

RESUMEN

Glucose, fructose and mannose are the preferred carbon/energy sources for the yeast Saccharomyces cerevisiae. Absence of preferred energy sources activates glucose derepression, which is regulated by the kinase Snf1. Snf1 phosphorylates the transcriptional repressor Mig1, which results in its exit from the nucleus and subsequent derepression of genes. In contrast, Snf1 is inactive when preferred carbon sources are available, which leads to dephosphorylation of Mig1 and its translocation to the nucleus where Mig1 acts as a transcription repressor. Here we revisit the role of the three hexose kinases, Hxk1, Hxk2 and Glk1, in glucose de/repression. We demonstrate that all three sugar kinases initially affect Mig1 nuclear localization upon addition of glucose, fructose and mannose. This initial import of Mig1 into the nucleus was temporary; for continuous nucleocytoplasmic shuttling of Mig1, Hxk2 is required in the presence of glucose and mannose and in the presence of fructose Hxk2 or Hxk1 is required. Our data suggest that Mig1 import following exposure to preferred energy sources is controlled via two different pathways, where (1) the initial import is regulated by signals derived from metabolism and (2) continuous shuttling is regulated by the Hxk2 and Hxk1 proteins. Mig1 nucleocytoplasmic shuttling appears to be important for the maintenance of the repressed state in which Hxk1/2 seems to play an essential role.


Asunto(s)
Núcleo Celular/metabolismo , Fructosa/metabolismo , Glucosa/metabolismo , Hexoquinasa/metabolismo , Manosa/metabolismo , Proteínas Represoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Transporte Activo de Núcleo Celular , Regulación Fúngica de la Expresión Génica , Hexoquinasa/genética , Fosforilación , Transporte de Proteínas , Proteínas Represoras/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Proteínas de Saccharomyces cerevisiae/genética
13.
PLoS One ; 15(1): e0227130, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31923283

RESUMEN

Success of invasive non-native plant species management is usually measured as changes in the abundance of the invasive plant species or native plant species following invader management, but more complex trophic responses to invader removal are often ignored or assumed. Moreover, the effects of invader removal at different stages of the invasion process is rarely evaluated, despite a growing recognition that invader impacts are density or stage-dependent. Therefore, the effectiveness of invasive species management for restoring community structure and function across trophic levels remains poorly understood. We determined how soil nematode diversity and community composition respond to removal of the globally invasive tree species Pinus contorta at different stages of invasion by reanalysing and expanding an earlier study including uninvaded vegetation (seedlings removed continuously), early invader removal (saplings removed), late removal (trees removed), and no removal (invaded). These treatments allowed us to evaluate the stage-dependent belowground trophic responses to biological invasion and removal. We found that invaded plots had half the nematode taxa richness compared to uninvaded plots, and that tree invasion altered the overall composition of the nematode community. Differences in nematode community composition between uninvaded nematode communities and those under the tree removal strategy tended to dilute higher up the food chain, whereas the composition of uninvaded vs. sapling removal strategies did not differ significantly. Conversely, the composition of invaded compared to uninvaded nematode communities differed across all trophic levels, altering the community structure and function. Specifically, invaded communities were structurally simplified compared to uninvaded communities, and had a higher proportion of short life cycle nematodes, characteristic of disturbed environments. We demonstrate that a shift in management strategies for a globally invasive tree species from removing trees to earlier removal of saplings is needed for maintaining the composition and structure of soil nematode communities to resemble uninvaded conditions.


Asunto(s)
Especies Introducidas , Nematodos/fisiología , Suelo/parasitología , Árboles/parasitología , Animales , Ecosistema , Infecciones por Nematodos , Pinus
14.
Oecologia ; 190(4): 891-899, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31273519

RESUMEN

Woody plant expansion into grasslands is widespread, driven by both successions to dominance by native woody species or invasion by non-native woody species. These shifts from grass- to woody-dominated systems also have profound effects on both above- and belowground communities and ecosystem processes. Woody-plant expansion should also alter the functional composition of the soil biota, including that of nematodes, which are major drivers of soil food-web structure and belowground processes, but such belowground impacts are poorly understood. We determined whether succession by a widespread native (Kunzea ericoides) and invasion by a non-native woody species (Pinus nigra) into tussock grasslands affect the composition of nematode functional guilds and the structure of nematode-based food webs. Although increasing dominance by woody species in both systems altered the functional guild composition of the nematode community, we found contrasting responses of nematode functional guilds to the different dominant plant species. Specifically, nematode communities reflected conditions of resource enrichment with increasing K. ericoides tree cover, whereas communities became structurally simplified and dominated by stress-tolerant nematode families with increasing P. nigra tree cover. Because nematodes regulate both bacterial- and fungal-dominated food webs in soils, these shifts could in turn alter multiple ecosystem processes belowground such as nutrient cycling. Incorporating species' functional traits into the assessment of habitat-change impacts on communities can greatly improve our understanding of species responses to environmental changes and their consequences in ecosystems.


Asunto(s)
Nematodos , Suelo , Animales , Ecosistema , Plantas , Madera
15.
Mol Cell ; 70(4): 745-756.e6, 2018 05 17.
Artículo en Inglés | MEDLINE | ID: mdl-29775585

RESUMEN

Transcription is a highly regulated and inherently stochastic process. The complexity of signal transduction and gene regulation makes it challenging to analyze how the dynamic activity of transcriptional regulators affects stochastic transcription. By combining a fast-acting, photo-regulatable transcription factor with nascent RNA quantification in live cells and an experimental setup for precise spatiotemporal delivery of light inputs, we constructed a platform for the real-time, single-cell interrogation of transcription in Saccharomyces cerevisiae. We show that transcriptional activation and deactivation are fast and memoryless. By analyzing the temporal activity of individual cells, we found that transcription occurs in bursts, whose duration and timing are modulated by transcription factor activity. Using our platform, we regulated transcription via light-driven feedback loops at the single-cell level. Feedback markedly reduced cell-to-cell variability and led to qualitative differences in cellular transcriptional dynamics. Our platform establishes a flexible method for studying transcriptional dynamics in single cells.


Asunto(s)
Regulación Fúngica de la Expresión Génica , Optogenética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Análisis de la Célula Individual/métodos , Procesos Estocásticos , Transcripción Genética , Modelos Genéticos , Saccharomyces cerevisiae/crecimiento & desarrollo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
16.
PLoS One ; 13(3): e0190557, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29561837

RESUMEN

Birds in U.S. national parks find strong protection from many longstanding and pervasive threats, but remain highly exposed to effects of ongoing climate change. To understand how climate change is likely to alter bird communities in parks, we used species distribution models relating North American Breeding Bird Survey (summer) and Audubon Christmas Bird Count (winter) observations to climate data from the early 2000s and projected to 2041-2070 (hereafter, mid-century) under high and low greenhouse gas concentration trajectories, RCP8.5 and RCP2.6. We analyzed climate suitability projections over time for 513 species across 274 national parks, classifying them as improving, worsening, stable, potential colonization, and potential extirpation. U.S. national parks are projected to become increasingly important for birds in the coming decades as potential colonizations exceed extirpations in 62-100% of parks, with an average ratio of potential colonizations to extirpations of 4.1 in winter and 1.4 in summer under RCP8.5. Average species turnover is 23% in both summer and winter under RCP8.5. Species turnover (Bray-Curtis) and potential colonization and extirpation rates are positively correlated with latitude in the contiguous 48 states. Parks in the Midwest and Northeast are expected to see particularly high rates of change. All patterns are more extreme under RCP8.5 than under RCP2.6. Based on the ratio of potential colonization and extirpation, parks were classified into overall trend groups associated with specific climate-informed conservation strategies. Substantial change to bird and ecological communities is anticipated in coming decades, and current thinking suggests managing towards a forward-looking concept of ecological integrity that accepts change and novel ecological conditions, rather than focusing management goals exclusively on maintaining or restoring a static set of historical conditions.


Asunto(s)
Aves , Cambio Climático , Conservación de los Recursos Naturales , Modelos Biológicos , Parques Recreativos , Análisis de Varianza , Animales , Demografía , Estaciones del Año , Estados Unidos
18.
Microsyst Nanoeng ; 4: 8, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-31057898

RESUMEN

Growth rate is a widely studied parameter for various cell-based biological studies. Growth rates of cell populations can be monitored in chemostats and micro-chemostats, where nutrients are continuously replenished. Here, we present an integrated microfluidic platform that enables long-term culturing of non-adherent cells as well as parallel and mutually independent continuous monitoring of (i) growth rates of cells by means of impedance measurements and of (ii) specific other cellular events by means of high-resolution optical or fluorescence microscopy. Yeast colonies were grown in a monolayer under culturing pads, which enabled high-resolution microscopy, as all cells were in the same focal plane. Upon cell growth and division, cells leaving the culturing area passed over a pair of electrodes and were counted through impedance measurements. The impedance data could then be used to directly determine the growth rates of the cells in the culturing area. The integration of multiple culturing chambers with sensing electrodes enabled multiplexed long-term monitoring of growth rates of different yeast strains in parallel. As a demonstration, we modulated the growth rates of engineered yeast strains using calcium. The results indicated that impedance measurements provide a label-free readout method to continuously monitor the changes in the growth rates of the cells without compromising high-resolution optical imaging of single cells.

19.
Methods Mol Biol ; 1672: 537-555, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29043647

RESUMEN

Time-lapse fluorescence imaging of yeast cells allows the study of multiple fluorescent targets in single cells, but is often hampered by the tedious cultivation using agar pads or glass bottom wells. Here, we describe the fabrication and operation of a microfluidic device for long-term imaging of yeast cells under constant or changing media conditions. The device allows acquisition of high quality images as cells are fixed in a two-dimensional imaging plane. Four yeast strains can be analyzed simultaneously over several days while up to four different media can be flushed through the chip. The microfluidic device does not rely on specialized equipment for its operation. To illustrate the use of the chip in DNA damage research, we show how common readouts for DNA damage or genomic instability behave upon induction with genotoxic chemicals (MMS, HU) or induction of a single double-strand break using induced CRISPR-Cas9 expression.


Asunto(s)
Dispositivos Laboratorio en un Chip , Imagen de Lapso de Tiempo/instrumentación , Imagen de Lapso de Tiempo/métodos , Levaduras , Sistemas CRISPR-Cas , Daño del ADN , Diseño de Equipo , Inestabilidad Genómica , Técnicas Analíticas Microfluídicas , Microscopía Fluorescente , Saccharomyces cerevisiae , Análisis de la Célula Individual
20.
Curr Opin Insect Sci ; 17: 92-97, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27720080

RESUMEN

As climate change moves insect systems into uncharted territory, more knowledge about insect dynamics and the factors that drive them could enable us to better manage and conserve insect communities. Climate change may also require us to revisit insect management goals and strategies and lead to a new kind of scientific engagement in management decision-making. Here we make five key points about the role of insect science in aiding and crafting management decisions, and we illustrate those points with the monarch butterfly and the Karner blue butterfly, two species undergoing considerable change and facing new management dilemmas. Insect biology has a strong history of engagement in applied problems, and as the impacts of climate change increase, a reimagined ethic of entomology in service of broader society may emerge. We hope to motivate insect biologists to contribute time and effort toward solving the challenges of climate change.


Asunto(s)
Cambio Climático , Ecosistema , Insectos/fisiología , Animales , Conservación de los Recursos Naturales/tendencias , Toma de Decisiones , Entomología/tendencias
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