Integration of the Unfolded Protein and Oxidative Stress Responses through SKN-1/Nrf

The Unfolded Protein Response (UPR) maintains homeostasis in the endoplasmic reticulum (ER) and defends against ER stress, an underlying factor in various human diseases. During the UPR, numerous genes are activated that sustain and protect the ER. These responses are known to involve the canonical UPR transcription factors XBP1, ATF4, and ATF6. Here, we show in C. elegans that the conserved stress defense factor SKN-1/Nrf plays a central and essential role in the transcriptional UPR. While SKN-1/Nrf has a well-established function in protection against oxidative and xenobiotic stress, we find that it also mobilizes an overlapping but distinct response to ER stress. SKN-1/Nrf is regulated by the UPR, directly controls UPR signaling and transcription factor genes, binds to common downstream targets with XBP-1 and ATF-6, and is present at the ER. SKN-1/Nrf is also essential for resistance to ER stress, including reductive stress. Remarkably, SKN-1/Nrf-mediated responses to oxidative stress depend upon signaling from the ER. We conclude that SKN-1/Nrf plays a critical role in the UPR, but orchestrates a distinct oxidative stress response that is licensed by ER signaling. Regulatory integration through SKN-1/Nrf may coordinate ER and cytoplasmic homeostasis

Dark Production: A Significant Source of Oceanic COS

Carbonyl sulfide (COS) in air and dissolved in seawater was determined during a cruise in August 1999 in the Sargasso Sea in the northwest Atlantic Ocean. Dissolved concentrations at the sea surface displayed only a weak diel cycle with a mean of 8.6 ± 2.8 pmol dm−3 owing to low abundance of photochemical precursors and high temperatures causing rapid hydrolysis. Depth profiles measured over the oceanic mixed layer revealed significant vertical gradients of COS concentration with higher values at the surface, suggesting that the rate of photochemical production at the surface exceeds the rate of vertical mixing. The mean atmospheric mixing ratio was 486 ± 40 ppt, and calculated sea-air fluxes ranged from 0.03 to 0.8 g COS km−2 d−1. COS dark production, estimated from the predawn COS concentration at the surface and the hydrolysis constant, contributed significantly to the total amount of COS produced. A strong temperature dependence of the COS dark production rate q was found by comparing previously published values. The data further indicate an approximately first-order relationship between q and chromophoric dissolved organic matter (CDOM) absorbance at 350 nm, a350, which is used as a proxy for the CDOM content of the water but is likely to covary with other parameters, such as biological activity, that could also affect COS dark production. Together with known functions for COS hydrolysis and solubility, the parameterization of dark production as a function of temperature and a350 allows for the prediction of COS concentrations and saturation ratios as a function of physical and optical seawater properties in the absence of photoproduction. This is used to estimate a lower limit of 0.056 Tg COS yr−1 to the annual COS flux from the ocean to the atmosphere

Does mesocosm validation of environmental DNA methods translate to natural environment monitoring applications? A case study detecting a high-profile invader; the red eared slider turtle, Trachemys scripta elegans, in Australia

Environmental DNA (eDNA) surveys have gained popularity as a highly sensitive detection tool that generally outperform traditional detection techniques. eDNA surveys can provide a cost-effective means to identify species’ distributions and recent incursions, informing the control or containment of invasive species. The red-eared slider turtle, Trachemys scripta elegans, is one of the world’s most invasive species and is listed as a priority pest species for management in Australia. In this study, we validate two eDNA assays to detect this invasive turtle in Australia. We demonstrate high sensitivity in a laboratory setting and perfect detection rates in mesocosms for one of these eDNA assays but show that this does not translate to high detection rates in urban waterbodies at sites of known occupancy. In fact, our results suggest eDNA surveys provide sub-optimal performance compared to traditional detection methods for T.s. elegans. We suggest the capacity for eDNA surveys to provide a highly sensitive detection tool must be evaluated in natural environments on a species-by-species basis to understand any limitations and to avoid high error rates from eDNA surveys leading to wasted resources or inappropriate management decisions. For management of T.s. elegans in Australia, clearly defining the utility of certain eDNA based approaches to detect T.s. elegans and their incursions is vital for effective management of this pest species.</p

Personal Attitudes Toward Weight in Overweight and Obese US Hemodialysis Patients

Objective Overweight and obesity have become increasingly common among end-stage renal disease patients on hemodialysis. Yet, little attention has been given to what hemodialysis patients themselves think of their weight, how they perceive it affects their health, and their attitudes about or desire for weight reduction. We explored these issues using a survey that we designed specifically for the dialysis population. Design and Methods Sixty-six chronic hemodialysis patients from a US urban center with a body mass index ≥25 kg/m2 and stable weight were recruited to participate in a cross-sectional study. The 12-question weight-related survey was validated by retesting a random portion of the study population. Results Based on test–retest results, the survey had good to excellent validity. Seventy-nine percent of patients were black, 49% were male, 29% were overweight, and 71% were obese. In general, the patients underestimated their weight excess though 73% were interested in weight loss, of whom nearly half reported attempting to do so mostly through diet and exercise. The majority of participants interested in losing weight felt that doing so would improve their physical and emotional health. The most common barrier to weight reduction was a belief that it was too difficult (55%), followed by a lack of motivation, money, time, resources, and knowledge. Diet was the most common weight loss strategy (85%) considered, whereas bariatric surgery was the least common (6.1%). Conclusions A majority of overweight and obese hemodialysis patients believe their excess weight is adversely impacting their health and quality of life and therefore wish to lose weight