Structural and Functional Characterization of a Novel Scorpion Toxin that Inhibits Na1.8 via Interactions With the DI Voltage Sensor and DII Pore Module.

Voltage-gated sodium channel Na1.8 regulates transmission of pain signals to the brain. While Na1.

Gut Microbial Ecology of Five Species of Sympatric Desert Rodents in Relation to Herbivorous and Insectivorous Feeding Strategies.

The gut microbial communities of mammals provide numerous benefits to their hosts. However, given the recent development of the microbiome field, we still lack a thorough understanding of the variety of ecological and evolutionary factors that structure these communities across species. Metabarcoding is a powerful technique that allows for multiple microbial ecology questions to be investigated simultaneously.

Mistreatment Experiences, Protective Workplace Systems, and Occupational Distress in Physicians.

Importance: Reducing physician occupational distress requires understanding workplace mistreatment, its relationship to occupational well-being, and how mistreatment differentially impacts physicians of diverse identities.

Objectives: To assess the prevalence and sources of mistreatment among physicians and associations between mistreatment, occupational well-being, and physicians' perceptions of protective workplace systems.

Design, Setting, And Participants: This survey study was administered in September and October 2020 to physicians at a large academic medical center.

Occult Untreated Alcohol Use Disorder in a Patient with Recurrent Pituitary Macroadenoma.

Alcohol use disorder (AUD) is a chronic relapsing and remitting psychiatric condition associated with adverse health outcomes. Although common, AUD is underdiagnosed, and treatment is often overlooked. At times of increased risk, such as the postoperative period, it is imperative to screen for and treat AUD to improve patient outcomes.

Defensive Venoms: Is Pain Sufficient for Predator Deterrence?

Pain, though unpleasant, is adaptive in calling an animal's attention to potential tissue damage. A long list of animals representing diverse taxa possess venom-mediated, pain-inducing bites or stings that work by co-opting the pain-sensing pathways of potential enemies. Typically, such venoms include toxins that cause tissue damage or disrupt neuronal activity, rendering painful stings honest indicators of harm.

Sex Differences in Defensive Behavior and Venom of The Striped Bark Scorpion Centruroides vittatus (Scorpiones: Buthidae).

Studies of venom variability have advanced from describing the mechanisms of action and relative potency of medically important toxins to understanding the ecological and evolutionary causes of the variability itself. While most studies have focused on differences in venoms among taxa, populations, or age-classes, there may be intersexual effects as well. Striped bark scorpions (Centruroides vittatus) provide a good model for examining sex differences in venom composition and efficacy, as this species exhibits dramatic sexual dimorphism in both size and defensive behavior; when threatened by an enemy, larger, slower females stand and fight while smaller, fleeter males prefer to run.

Influence of vanadium-doping on the magnetism of FeCo/SiO2 nanoparticle.

FeCo nanoparticles (4 ± 1 nm), encapsulated by SiO2, were synthesized with and without a 2% (atomic ratio) vanadium doping. The impact from the presence of vanadium, an additive often used in the bulk to alter both physical and mechanical properties, on the nanomagnetism was probed by element-specific X-ray spectroscopy and magnetometry techniques. While the nanostructure was unaffected by the addition of 2% vanadium, the temperature dependent magnetic properties were altered significantly, such as the increased coercivity and an exchange bias field shift.

Predatory grasshopper mice.

A Quick Guide on grasshopper mice which, contrary to the great majority of mouse species, are obligate carnivores.

Redesigning a General Education Science Course to Promote Critical Thinking.

Recent studies question the effectiveness of a traditional university curriculum in helping students improve their critical thinking and scientific literacy. We developed an introductory, general education (gen ed) science course to overcome both deficiencies. The course, titled Foundations of Science, differs from most gen ed science offerings in that it is interdisciplinary; emphasizes the nature of science along with, rather than primarily, the findings of science; incorporates case studies, such as the vaccine-autism controversy; teaches the basics of argumentation and logical fallacies; contrasts science with pseudoscience; and addresses psychological factors that might otherwise lead students to reject scientific ideas they find uncomfortable.

Spontaneously formed interfacial metal silicates and their effect on the magnetism of superparamagnetic FeCo/SiO₂ core/shell nanoparticles.

The integration of superparamagnetic core/shell nanoparticles into devices and other nanoscale technological applications requires a detailed understanding of how the intimate contact between core and shell nanophases affects the magnetism. We report how, for single-domain FeCo nanoparticles, an FeCo phase unique to the nanoscale with silica shells of increasing thicknesses spontaneously formed interfacial metal silicates between the core and shell (such as Fe2SiO4 and Co2SiO4) and altered the overall magnetism of the nanomaterial significantly. The influence of this previously overlooked phenomenon on magnetic properties is reported.

Meek males and fighting females: sexually-dimorphic antipredator behavior and locomotor performance is explained by morphology in bark scorpions (Centruroides vittatus).

Sexual dimorphism can result from sexual or ecological selective pressures, but the importance of alternative reproductive roles and trait compensation in generating phenotypic differences between the sexes is poorly understood. We evaluated morphological and behavioral sexual dimorphism in striped bark scorpions (Centruroides vittatus). We propose that reproductive roles have driven sexually dimorphic body mass in this species which produces sex differences in locomotor performance.

Voltage-gated sodium channel in grasshopper mice defends against bark scorpion toxin.

Painful venoms are used to deter predators. Pain itself, however, can signal damage and thus serves an important adaptive function. Evolution to reduce general pain responses, although valuable for preying on venomous species, is rare, likely because it comes with the risk of reduced response to tissue damage.

Isolation and characterization of CvIV4: a pain inducing α-scorpion toxin.

Background: Among scorpion species, the Buthidae produce the most deadly and painful venoms. However, little is known regarding the venom components that cause pain and their mechanism of action. Using a paw-licking assay (Mus musculus), this study compared the pain-inducing capabilities of venoms from two species of New World scorpion (Centruroides vittatus, C.

Physiological resistance of grasshopper mice (Onychomys spp.) to Arizona bark scorpion (Centruroides exilicauda) venom.

Predators feeding on toxic prey may evolve physiological resistance to the preys' toxins. Grasshopper mice (Onychomys spp.) are voracious predators of scorpions in North American deserts.

Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk.

Ground squirrels (Spermophilus spp.) have evolved a battery of defences against the rattlesnakes (Crotalus spp.) that have preyed on them for millions of years.

Model of vapor-induced resistivity changes in gold-thiolate monolayer-protected nanoparticle sensor films.

An investigation of the modulation of charge transport through thin films of n-octanethiolate monolayer-protected gold nanoparticles (MPN) induced by the sorption of organic vapors is presented. A model is derived that allows predictions of MPN-coated chemiresistor (CR) responses from vapor-film partition coefficients, and analyte densities and dielectric constants. Calibrations with vapors of 28 compounds collected from an array of CRs and a parallel thickness-shear-mode resonator are used to verify assumptions inherent in the model and to assess its performance.

Naturalistic color discriminations in polymorphic platyrrhine monkeys: effects of stimulus luminance and duration examined with functional substitution.

X-linked photopigment polymorphism produces six different color vision phenotypes in most species of New World monkey. In the subfamily Callitrichinae, the three M/L alleles underlying these different phenotypes are present at unequal frequencies suggesting that selective pressures other than heterozygous-advantage operate on these alleles. Earlier we investigated this hypothesis with functional substitution, a technique using a computer monitor to simulate colors as they would appear to humans with monkey visual pigments (Visual Neuroscience 21:217-222, 2004).

Exploiting charge-transfer complexation for selective measurement of gas-phase olefins with nanoparticle-coated chemiresistors.

Charge-transfer-mediated olefin-selective sensing by use of chemiresistors (CR) coated with composite films of n-octanethiolate-monolayer-protected gold nanoparticles (C8-MPN) and each of several square-planar PtCl2(olefin)(pyridine) coordination complexes is described. Where the gas-phase olefin analyte differs from that initially coordinated to Pt, olefin substitution occurs and is accompanied by a persistent shift in the composite film resistance. Commensurate changes in film mass are also observed with a similarly coated thickness shear mode resonator.

Cone pigment polymorphism in New World monkeys: are all pigments created equal?

Most platyrrhine monkeys have a triallelic M/L opsin gene polymorphism that underlies significant individual variations in color vision. A survey of the frequencies of these polymorphic genes suggests that the three alleles occur with equal frequency among squirrel monkeys (subfamily Cebinae), but are not equally frequent in a number of species from the subfamily Callitrichinae. This departure from equal frequency in the Callitrichids should slightly increase the ratio of dichromats to trichromats in the population and significantly alter the relative representation of the three possible dichromatic and trichromatic phenotypes.

Evolution of vertebrate colour vision.

Recent years have witnessed a growing interest in learning how colour vision has evolved. This trend has been fuelled by an enhanced understanding of the nature and extent of colour vision among contemporary species, by a deeper understanding of the paleontological record and by the application of new tools from molecular biology. This review provides an assessment of the progress in understanding the evolution of vertebrate colour vision.

Optimal mechanisms for finding and selecting mates: how threespine stickleback ( Gasterosteus aculeatus) should encode male throat colors.

Male threespine stickleback ( Gasterosteus aculeatus) use nuptial colors to attract mates and intimidate rivals. We quantified stickleback color and environmental lighting using methods independent of human perception to evaluate the information transmitted by male signals in a habitat where these signals are displayed. We also developed models of chromatic processing based on four cone photopigments (peak absorptions at 360, 445, 530, and 605 nm) characterized microspectrophotometrically in G.

The rattling sound of rattlesnakes (Crotalus viridis) as a communicative resource for ground squirrels (Spermophilus beecheyi) and burrowing owls (Athene cunicularia).

Animal communication involves very dynamic processes that can generate new uses and functions for established communicative activities. In this article, the authors describe how an aposematic signal, the rattling sound of rattlesnakes (Crotalus viridis), has been exploited by 2 ecological associates of rattlesnakes: (a) California ground squirrels (Spermophilus beecheyi) use incidental acoustic cues in rattling sounds to assess the danger posed by the rattling snake, and (b) burrowing owls (Athene cunicularia) defend themselves against mammalian predators by mimicking the sound of rattling. The remarkable similarity between the burrowing owl's defensive hiss and the rattlesnake's rattling reflects both exaptation and adaptation.

Assessment of rattlesnake dangerousness by California ground squirrels: exploitation of cues from rattling sounds.

We propose that the predator-prey relationship between California ground squirrels, Spermophilus beecheyi beecheyi, and northern Pacific rattlesnakes, Crotalus viridis oreganus, offers a compelling analogy with the well-studied case of intraspecific fighting and assessment. Because ground squirrels frequently place themselves at risk by harassing rattlesnakes, they stand to benefit from assessment strategies which serve to mediate risk. For example, larger and warmer snakes are more dangerous than smaller and cooler ones.

Conflict and assessment in a predator-prey system: ground squirrels versus rattlesnakes.

Adult California ground squirrels, Spermophilus beecheyi beecheyi, actively confront and harass northern Pacific rattlesnakes, Crotalus viridis oreganus, which are the principal predator of ground squirrel pups. In this report we examine the roles of risk (snake size) and context (location of encounter and squirrel reproductive category) in rattlesnake assessment by ground squirrels. In interpreting the results, we borrow heavily from the well-developed conceptual framework applied in the analogous case of intraspecific conflict.

Target detection in optically scattering media by polarization-difference imaging.

Polarization-difference imaging (PDI) was recently presented by us as a method of imaging through scattering media [Opt. Lett. 20, 608 (1995)].