RESUMEN

Temperature can impact every reaction essential to a cell. For organisms that cannot regulate their own temperature, adapting to temperatures that fluctuate unpredictably and on variable timescales is a major challenge. Extremes in the magnitude and frequency of temperature changes are increasing across the planet, raising questions as to how the biosphere will respond. To examine mechanisms of adaptation to temperature, we collected wild isolates from different climates of the fungus Ashbya gossypii, which has a compact genome of only ∼4,600 genes. We found control of the nuclear division cycle and polarized morphogenesis, both critical processes for fungal growth, were temperature sensitive and varied among the isolates. The phenotypes were associated with naturally varying sequences within the glutamine-rich region (QRR) IDR of an RNA-binding protein called Whi3. This protein regulates both nuclear division and polarized growth via its ability to form biomolecular condensates. In cells and in cell-free reconstitution assays, we found that temperature tunes the properties of Whi3-based condensates. Exchanging Whi3 sequences between isolates was sufficient to rescue temperature-sensitive phenotypes, and specifically, a heptad repeat sequence within the QRR confers temperature-sensitive behavior. Together, these data demonstrate that sequence variation in the size and composition of an IDR can promote cell adaptation to growth at specific temperature ranges. These data demonstrate the power of IDRs as tuning knobs for rapid adaptation to environmental fluctuations.

Asunto(s)

RESUMEN

Temperature can impact every reaction and molecular interaction essential to a cell. For organisms that cannot regulate their own temperature, a major challenge is how to adapt to temperatures that fluctuate unpredictability and on variable timescales. Biomolecular condensation offers a possible mechanism for encoding temperature-responsiveness and robustness into cell biochemistry and organization. To explore this idea, we examined temperature adaptation in a filamentous-growing fungus called Ashbya gossypii that engages biomolecular condensates containing the RNA-binding protein Whi3 to regulate mitosis and morphogenesis. We collected wild isolates of Ashbya that originate in different climates and found that mitotic asynchrony and polarized growth, which are known to be controlled by the condensation of Whi3, are temperature sensitive. Sequence analysis in the wild strains revealed changes to specific domains within Whi3 known to be important in condensate formation. Using an in vitro condensate reconstitution assay we found that temperature impacts the relative abundance of protein to RNA within condensates and that this directly impacts the material properties of the droplets. Finally, we found that exchanging Whi3 genes between warm and cold isolates was sufficient to rescue some, but not all, condensate-related phenotypes. Together these data demonstrate that material properties of Whi3 condensates are temperature sensitive, that these properties are important for function, and that sequence optimizes properties for a given climate.

RESUMEN

BACKGROUND: Health care organizations are designing comprehensive care programs to reduce hospital utilization by high-risk patients with multiple chronic illnesses. LOCAL PROBLEM: A community hospital recognized patients with multiple chronic conditions had higher rates of inpatient stays and emergency department (ED) visits. METHODS: Patients (n = 36) with multiple chronic conditions enrolled in a supportive care program. Researchers analyzed hospital utilization, inpatient stays, and ED visits preintervention and postgraduation for the participants enrolled. Palliative care nurses were assigned to patients enrolled in the supportive care program. RESULTS: There was a statistically significant decrease in hospital utilization (Z = -2.540, P = .011) and inpatient stays (Z = -4.037, P < .001) following the implementation of the supportive care program. CONCLUSIONS: The study met its aim of reducing hospital utilization and inpatient stays by creating a comprehensive approach to support high-risk patients in self-management of their chronic illnesses.

Asunto(s)

RESUMEN

Arsenic contamination in groundwater is a public health and environmental concern in the United States (U.S.) particularly where monitoring is not required under the Safe Water Drinking Act. Previous studies suggest the influence of regional mechanisms for arsenic mobilization into groundwater; however, no study has examined how influencing parameters change at a continental scale spanning multiple regions. We herein examine covariates for groundwater in the western, central and eastern U.S. regions representing mechanisms associated with arsenic concentrations exceeding the U.S. Environmental Protection Agency maximum contamination level (MCL) of 10 parts per billion (ppb). Statistically significant covariates were identified via classification and regression tree (CART) analysis, and included hydrometeorological and groundwater chemical parameters. The CART analyses were performed at two scales: national and regional; for which three physiographic regions located in the western (Payette Section and the Snake River Plain), central (Osage Plains of the Central Lowlands), and eastern (Embayed Section of the Coastal Plains) U.S. were examined. Validity of each of the three regional CART models was indicated by values >85% for the area under the receiver-operating characteristic curve. Aridity (precipitation minus potential evapotranspiration) was identified as the primary covariate associated with elevated arsenic at the national scale. At the regional scale, aridity and pH were the major covariates in the arid to semi-arid (western) region; whereas dissolved iron (taken to represent chemically reducing conditions) and pH were major covariates in the temperate (eastern) region, although additional important covariates emerged, including elevated phosphate. Analysis in the central U.S. region indicated that elevated arsenic concentrations were driven by a mixture of those observed in the western and eastern regions.

Asunto(s)

RESUMEN

Similar to fracking, the development of tar sand mining in the U.S. has moved faster than understanding of potential water quality impacts. Potential water quality impacts of tar sand mining, processing, and disposal to springs in canyons incised approximately 200 m into the Tavaputs Plateau, at the Uinta Basin southern rim, Utah, USA, were evaluated by hydrogeochemical sampling to determine potential sources of recharge, and chemical thermodynamic estimations to determine potential changes in transfer of bitumen compounds to water. Because the ridgetops in an area of the Tavaputs Plateau named PR Spring are starting to be developed for their tar sand resource, there is concern for potential hydrologic connection between these ridgetops and perennial springs in adjacent canyons on which depend ranching families, livestock, wildlife and recreationalists. Samples were collected from perennial springs to examine possible progression with elevation of parameters such as temperature, specific conductance, pH, dissolved oxygen, isotopic tracers of phase change, water-rock interaction, and age since recharge. The groundwater age dates indicate that the springs are recharged locally. The progression of hydrogeochemical parameters with elevation, in combination with the relatively short groundwater residence times, indicate that the recharge zone for these springs includes the surrounding ridges, and thereby suggests a hydrologic connection between the mining, processing, disposal area and the springs. Estimations based on chemical thermodynamic approaches indicate that bitumen compounds will have greatly enhanced solubility in water that comes into contact with the residual bitumen-solvent mixture in disposed tailings relative to water that currently comes into contact with natural tar.

Asunto(s)