We study partisan differences in Americans' response to the COVID-19 pandemic. Political leaders and media outlets on the right and left have sent divergent messages about the severity of the crisis, ...which could impact the extent to which Republicans and Democrats engage in social distancing and other efforts to reduce disease transmission. We develop a simple model of a pandemic response with heterogeneous agents that clarifies the causes and consequences of heterogeneous responses. We use location data from a large sample of smartphones to show that areas with more Republicans engaged in less social distancing, controlling for other factors including public policies, population density, and local COVID cases and deaths. We then present new survey evidence of significant gaps at the individual level between Republicans and Democrats in self-reported social distancing, beliefs about personal COVID risk, and beliefs about the future severity of the pandemic.
In Southern British Columbia (BC), Canada, declines in southern resident killer whale (SRKW-Orcinus orca) populations have been linked to declines in numbers and average size of their preferred prey, ...Chinook salmon (Oncorhynchus tshawytscha). However, the life history diversity of Chinook suggests that there is a need to assess stock-specific differences in energy density to evaluate prey quality as a factor in SRKW declines. In this study, we calibrated a Distell fat meter to estimate Chinook whole-body lipid content, a proxy for energy density. The fat meter was deployed at the Fraser River, BC, Chinook test fishery during 2020, collecting lipid, weight, and length measurements from 1566 genetically stock identified individuals encompassing all major Fraser River Chinook population units (management units, MUs) at river entry. We found that MU-specific lipid content increased with distance and elevation to spawning grounds and was highest in the Spring-5
(12.8%) and Summer-5
(12.7%) MUs, intermediate in the Summer-4
MU (10.8%), and lowest in the Fall-4
MU (7.3%). Lipid content also decreased by up to 6 percentage points within MUs from the beginning to end of their migration period. Our data revealed SRKWs' most endangered prey sources, the Spring-5
and Summer-5
MUs, are also its most energy rich. It also indicated SRKWs have access to progressively lower energy density Chinook through the year, requiring up to ~ 30% more fish to meet energy demands in the fall than in the spring.
The pelagic food webs of British Columbia’s (BC) coastal oceans have never had a comprehensive review of their trophic structure. In this study, we analyzed carbon (δ 13 C) and nitrogen (δ 15 N) ...stable isotope ratios of pelagic food web components collected from four regions in southern BC: Juan de Fuca Strait, the Strait of Georgia, Queen Charlotte Strait, and Queen Charlotte Sound during an August 2019 survey. In addition, conductivity, temperature, and depth (CTD), chlorophyll, and nutrient data were collected to assess the oceanographic basis for regionalization. Between regions, we observed differences in the isotopic baseline driven by regional oceanography. Likewise, we also observed oceanography-driven differences in regional food chain length, carbon range, and isotopic overlap. Species-specific trophic level and isotopic niche were determined. For common pelagic species, we described how trophic level varied regionally, was not always in line with previously published dietary data, and instead largely tracked regional changes in food chain length. We conclude that variable food web properties and trophic ecology can manifest across the small spatial scales of the BC coast’s discrete regions.
Abstract
In coastal marine food webs, food chain length and the distribution of trophic levels mediate the impacts of emerging threats such as overfishing, pollution, and climate change, through ...their effect on essential properties such as productivity, connectivity, and energy transfer efficiency. These two components of food web structure are therefore an essential element of ecosystem-based management; however, what drives them remains poorly understood. It has been hypothesized that high primary production drives lower trophic levels and shorter food chain length in coastal regions. Here, we evaluate this hypothesis on the British Columbia (BC) coast as this coastal marine ecosystem is comprised of regions with contrasting levels of primary production. We measured nitrogen stable isotopes from zooplankton, micronekton, and nekton collected from four of the main water bodies of southern BC during a survey completed in August of 2019. We used Sentinel-3 satellite data to determine overall production in each region across a 5-year climatology and during the 2019 season. Results showed that primary production varied significantly between the four regions and that increases in phytoplankton biomass were driven by increases in microphytoplankton. Nitrogen isotope data demonstrated a significant inverse relationship between a region’s primary production and both total food chain length and trophic level in species sampled in multiple regions, but no change in the trophic structure of the zooplankton community across regions. Changes in species’ trophic levels were therefore driven by shifts in the level of zooplanktivory. These results support a model of bottom-up omnivory driving coastal food web structure, where levels of primary production, specifically biomass of microphytoplankton, determine food chain length and the distribution of trophic levels. High microphytoplankton biomass supports a large biomass of large grazing zooplankton, which drive increases in omnivorous feeding behaviour among the micronekton and nekton.
Leukocyte telomere length (LTL) is a complex genetic trait. It shortens with age and is associated with a host of aging-related disorders. Recent studies have observed that offspring of older fathers ...have longer LTLs. We explored the relation between paternal age and offspring's LTLs in 4 different cohorts. Moreover, we examined the potential cause of the paternal age on offspring's LTL by delineating telomere parameters in sperm donors. We measured LTL by Southern blots in Caucasian men and women (n=3365), aged 18-94 years, from the Offspring of the Framingham Heart Study (Framingham Offspring), the NHLBI Family Heart Study (NHLBI-Heart), the Longitudinal Study of Aging Danish Twins (Danish Twins), and the UK Adult Twin Registry (UK Twins). Using Southern blots, Q-FISH, and flow-FISH, we also measured telomere parameters in sperm from 46 young (<30 years) and older (>50 years) donors. Paternal age had an independent effect, expressed by a longer LTL in males of the Framingham Offspring and Danish Twins, males and females of the NHLBI-Heart, and females of UK Twins. For every additional year of paternal age, LTL in offspring increased at a magnitude ranging from half to more than twice of the annual attrition in LTL with age. Moreover, sperm telomere length analyses were compatible with the emergence in older men of a subset of sperm with elongated telomeres. Paternal age exerts a considerable effect on the offspring's LTL, a phenomenon which might relate to telomere elongation in sperm from older men. The implications of this effect deserve detailed study.
An ongoing debate in demography has focused on whether the human lifespan has a maximal natural limit. Taking a mechanistic perspective, and knowing that short telomeres are associated with ...diminished longevity, we examined whether telomere length dynamics during adult life could set a maximal natural lifespan limit. We define leukocyte telomere length of 5 kb as the 'telomeric brink', which denotes a high risk of imminent death. We show that a subset of adults may reach the telomeric brink within the current life expectancy and more so for a 100-year life expectancy. Thus, secular trends in life expectancy should confront a biological limit due to crossing the telomeric brink.
Microbial translocation and innate immune action characterize HIV infection. Continued gut mucosal dysfunction during treatment and its relationship to CD4 T-cell recovery has not been well ...described.
A cross-sectional study was performed of antiretroviral therapy (ART)-suppressed (immunologic responders with CD4 > 500 cells/μl and immunologic nonresponders with CD4 < 350 cells/μl), untreated HIV-infected, and seronegative participants consenting to gut biopsies and a blood draw.
Neutrophil infiltration as a surrogate response to epithelial breach, colorectal epithelial proliferation as a measure of repair, and mucosal apoptosis by immunohistochemistry were determined in gut biopsies. Plasma markers of monocyte activation (sCD14), immune activation (interleukin-6), and indoleamine 2,3-dioxygenase-1 activity (plasma kynurenine/tryptophanratio) were concurrently measured.
Each HIV-infected group had greater neutrophil infiltration than controls. Similarly, untreated HIV-infected participants and ART-suppressed immunologic responders had increased epithelial proliferation compared with controls, but immunologic nonresponders had no appreciable increase in epithelial proliferation despite elevated neutrophil infiltration. The CD4 T-cell count was positively correlated with epithelial proliferation and was modestly negatively correlated with neutrophil infiltration in ART-suppressed patients. Epithelial proliferation was inversely correlated with mucosal apoptosis, and apoptosis was linked to plasma sCD14 and modestly to kynurenine/tryptophan ratio.
Neutrophil infiltration and mucosal apoptosis remain abnormally high despite ART. Epithelial proliferation increases in HIV, but may be impaired in immunologic nonresponders. Whether mucosal apoptosis is a cause or consequence of epithelial proliferative defects is unclear, but appears to be associated with systemic inflammation. The impact of ART and interventions targeting the gut epithelial barrier in treated HIV infection warrant further investigation.
One of the most important clinical obstacles in cystic fibrosis (CF) treatment is antibiotic treatment failure due to biofilms produced by
The ability of this pathogen to survive eradication by ...tobramycin and pathoadapt into a hyperbiofilm state leading to chronic infections is key to its success. Retrospective studies have demonstrated that preventing this pathoadaptation by improving eradication is essential to extend the lives of CF patients. To identify adjuvants that enhance tobramycin eradication of
, we performed a high-throughput screen of 6,080 compounds from four drug-repurposing libraries. We identified that the Food and Drug Administration (FDA)-approved compound triclosan, in combination with tobramycin, resulted in a 100-fold reduction of viable cells within biofilms at 6 h, but neither compound alone had significant antimicrobial activity against biofilms. This synergistic treatment significantly accelerated the killing of biofilms compared to that with tobramycin treatment alone, and the combination was effective against 6/7 CF clinical isolates compared to tobramycin treatment alone, including a tobramycin-resistant strain. Further, triclosan and tobramycin killed persister cells, causing a 100-fold reduction by 8 h and complete eradication by 24 h. Triclosan also enhances tobramycin killing of multiple
and
clinical isolates grown as biofilms. Additionally, triclosan showed synergy with other aminoglycosides, such as gentamicin or streptomycin. Triclosan is a well-tolerated aminoglycoside adjuvant shown to be safe for human use that could improve the treatment of biofilm-based infections.
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