Brown Bear Density and Estimated Harvest Rates in Northwestern Alaska

Human-caused mortality in general, and unregulated hunting in particular, have been implicated in reductions in brown bear (Ursus arctos) populations throughout much of their range. In northwestern Alaska, USA, bear densities have not been assessed in 20 years while harvest regulations have been liberalized, raising concerns that broad undetected population declines might occur. We used a modified mark-resight approach to estimate brown bear density during 2005–2018 in 4 subareas throughout the region. We also summarized harvest information for each subarea and used our survey results to estimate harvest rates. We estimated densities for independent bears assuming constant or heterogeneous probabilities of detection and occurrence. We present the results of the constant model for more direct comparison with past work and the heterogeneity model results to provide estimates of density that are less likely to be negatively biased. Using the constant model, we estimated the density of independent bears was 17.0, 49.2, 24.9, and 19.4/1,000 km² on portions of the Seward Peninsula, the lower Noatak River, the upper Noatak River, and Gates of the Arctic National Park and Preserve, respectively. These estimates are broadly similar to those from past work in interior and northwestern Alaska, with the exception of the lower Noatak River subarea where our estimates are the highest reported for a bear population in northern Alaska. We estimated that the harvest rate on the Seward Peninsula was approximately 5.2% or 7.7% on average, depending upon the model used. In the remaining areas, we estimated annual harvest rates were <2.5%, well within sustainability guidelines from past work. Overall, our results suggest that brown bear densities are similar or somewhat higher than in the past in much of northwestern Alaska and that current harvest rates are sustainable in most areas, except perhaps the Seward Peninsula. Ongoing survey work will be useful for further evaluating the assumptions of the modified mark-resight survey approach, assessing population trajectory, and determining the effect of harvest on brown bear populations. © 2021 The Wildlife Society.     

Sir2 deletion prevents lifespan extension in 32 long-lived mutants

Activation of Sir2 orthologs is proposed to increase lifespan downstream of dietary restriction. Here, we describe an examination of the effect of 32 different lifespan-extending mutations and four methods of DR on replicative lifespan (RLS) in the short-lived sir2Δ yeast strain. In every case, deletion of SIR2 prevented RLS extension; however, RLS extension was restored when both SIR2 and FOB1 were deleted in several cases, demonstrating that SIR2 is not directly required for RLS extension. These findings indicate that suppression of the sir2Δ lifespan defect is a rare phenotype among longevity interventions and suggest that sir2Δ cells senesce rapidly by a mechanism distinct from that of wild-type cells. They also demonstrate that failure to observe lifespan extension in a short-lived background, such as cells or animals lacking sirtuins, should be interpreted with caution.     

Long-term open-label response to atomoxetine in adult ADHD: influence of sex, emotional dysregulation, and double-blind response to atomoxetine

A three-year open-label study of atomoxetine in adults with ADHD followed two multicenter, double-blind trials. In the double-blind trials, female gender and higher levels of emotional symptoms were associated with better outcome. Following a 4-week placebo washout period, 384 (of 536) subjects continued into the open-label study. 61% of subjects entering this open-label study remained after 6?months at an average dose of 100?mg/day. Subjects who had previously responded to double-blind atomoxetine achieved maximum response after 8?weeks of open-label medication, but others continued to improve for 36?weeks. Women improved more (7.7?±?6.4) than men (6.1?±?6.4) on the Wender-Reimherr Adult Attention Deficit Disorder Scale (WRAADDS) (P?=?.007) and the Conners' Adult ADHD Rating Scale (P?=?.03). Subjects with emotional dysregulation improved more than others on the WRAADDS (P?=?.001). Responders ultimately improved approximately 60% in attentional, hyperactive/impulsive, and emotional symptoms. Thirty-nine percent of atomoxetine double-blind non-responders became responders during open-label treatment.     

Engineered Mitochondrial Ferritin as a Magnetic Resonance Imaging Reporter in Mouse Olfactory Epithelium

We report the design of a MRI reporter gene with applications to non-invasive molecular imaging. We modified mitochondrial ferritin to localize to the cell cytoplasm. We confirmed the efficient cellular processing of this engineered protein and demonstrated high iron loading in mammalian cells. The reporter’s intracellular localization appears as distinct clusters that deliver robust MRI contrast. We used this new reporter to image in vivo and ex vivo the gene expression in native olfactory sensory neurons in the mouse epithelium. This robust MRI reporter can facilitate the study of the molecular mechanisms of olfaction and to monitor intranasal gene therapy delivery, as well as a wide range of cell tracking and gene expression studies in living subjects.     

Role for mTOR signaling and neuronal activity in morphine-induced adaptations in ventral tegmental area dopamine neurons

While the abuse of opiate drugs continues to rise, the neuroadaptations that occur with long-term drug exposure remain poorly understood. We describe here a series of chronic morphine-induced adaptations in ventral tegmental area (VTA) dopamine neurons, which are mediated via downregulation of AKT-mTORC2 (mammalian target of rapamycin complex-2). Chronic opiates decrease the size of VTA dopamine neurons in rodents, an effect seen in humans as well, and concomitantly increase the excitability of the cells but decrease dopamine output to target regions. Chronic morphine decreases mTORC2 activity, and overexpression of Rictor,?a component of mTORC2, prevents morphine-induced changes in cell morphology and activity. Further, local knockout of Rictor in VTA decreases DA soma size and reduces rewarding responses to morphine, consistent with the hypothesis that these adaptations represent a mechanism of reward tolerance. Together, these findings demonstrate a novel role for AKT-mTORC2 signaling in mediating neuroadaptations to opiate drugs of abuse.     

Leaf litter identity alters the timing of lotic nutrient dynamics

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Combined climate‐ and prey‐mediated range expansion of Humboldt squid (Dosidicus gigas), a large marine predator in the California Current System

Climate‐driven range shifts are ongoing in pelagic marine environments, and ecosystems must respond to combined effects of altered species distributions and environmental drivers. Hypoxic oxygen minimum zones (OMZs) in midwater environments are shoaling globally; this can affect distributions of species both geographically and vertically along with predator–prey dynamics. Humboldt (jumbo) squid (Dosidicus gigas) are highly migratory predators adapted to hypoxic conditions that may be deleterious to their competitors and predators. Consequently, OMZ shoaling may preferentially facilitate foraging opportunities for Humboldt squid. With two separate modeling approaches using unique, long‐term data based on in situ observations of predator, prey, and environmental variables, our analyses suggest that Humboldt squid are indirectly affected by OMZ shoaling through effects on a primary food source, myctophid fishes. Our results suggest that this indirect linkage between hypoxia and foraging is an important driver of the ongoing range expansion of Humboldt squid in the northeastern Pacific Ocean.