Venom Expelled by Cottonmouths (Agkistrodon Piscivorus) Across Different Prey Sizes, Prey Taxa, and Snake Body Temperatures

Pit vipers possess a sophisticated venom delivery system enabling them to efficiently disable prey. To avoid retaliatory countermeasures, pit vipers typically release envenomated prey which are then trailed and consumed after succumbing to venom effects. Successful retrieval of released prey should vary with venom resistance and trail ability of prey types. The effects of prey size and prey type (mice, lizards, and frogs) on foraging behavior and venom expenditure in a cohort of juvenile cottonmouths was examined. Venom expenditure did not vary significantly among prey sizes or prey types. However, lizard prey were held significantly more often than mice. The effect of snake body temperature on foraging response variables across a range of ecologically relevant temperatures (18°C-30°C) was also examined. Cottonmouths injected significantly less venom, and held prey significantly more often, at 18°C than at 25°C or 30°C. These results are consistent with a thermal constraint on envenomation performance at lower operant temperatures. Overall, these results suggest that cottonmouths modify foraging behavior to compensate for both venom resistance in ectothermic prey and decreased performance at lower temperatures

An Erythristic Morph of Red-Backed Salamander (Plethodon cinereus) Collected in Virginia

Eight different color polymorphisms of the Red-backed Salamander (Plethodon cinereus) have been described throughout its range. Among them, the erythristic phenotype is a mimetic morph with coloration patterns similar to that of toxic Eastern Newt efts (Notophthalmus viridescens). We describe an erythristic morph of P. cinereus collected at Mountain Lake Biological Station, Virginia. To our knowledge, there are no prior published records of this morph in Virginia

The Indestructible Insect: Velvet Ants From Across the United States Avoid Predation by Representatives From All Major Tetrapod Clades

Velvet ants are a group of parasitic wasps that are well known for a suite of defensive adaptations including bright coloration and a formidable sting. While these adaptations are presumed to function in antipredator defense, observations between potential predators and this group are lacking. We conducted a series of experiments to determine the risk of velvet ants to a host of potential predators including amphibians, reptiles, birds, and small mammals. Velvet ants from across the United States were tested with predator\u27s representative of the velvet ants native range. All interactions between lizards, free-ranging birds, and a mole resulted in the velvet ants survival, and ultimate avoidance by the predator. Two shrews did injure a velvet ant, but this occurred only after multiple failed attacks. The only predator to successfully consume a velvet ant was a single American toad (Anaxyrus americanus). These results indicate that the suite of defenses possessed by velvet ants, including aposematic coloration, stridulations, a chemical alarm signal, a hard exoskeleton, and powerful sting are effective defenses against potential predators. Female velvet ants appear to be nearly impervious to predation by many species whose diet is heavily derived of invertebrate prey

Consumer Palatability of Beef Muscles From Australian and US Production Systems With or Without Enhancement

The objective was to assess the consumer (n = 360) palatability and satisfaction of enhanced (7%) and nonenhanced Australian grain-fed, Australian grass-fed, and US grain-fed beef from 2 beef muscles. Strip loin (longissimus lumborum [LL]) and top sirloin butt (gluteus medius [GM]) subprimals were collected from 12 Australian grass-fed, 12 Australian grain-fed, and 12 US grain-fed (USDA Choice) carcasses. In addition, tenderloin (psoas major) and eye of round (semitendinosus) subprimals were collected from the same US carcasses to serve as anchors for high and low palatability. All subprimals were aged until 29 to 32 d postmortem. All fabrication and enhancement occurred in Lubbock, Texas. Data were analyzed initially as a randomized complete design and subsequently as a split-split plot design, with the main effects of country of origin/diet (Australian grain-fed, Australian grass-fed, and US grain-fed), muscle (LL and GM), and enhancement (0% or 7%) and all potential interactions as fixed effects. Enhancement significantly improved palatability in both LL and GM steaks as evidenced by greater (P < 0.05) consumer ratings for tenderness, juiciness, flavor liking, overall liking, and satisfaction. Enhancing LL steaks resulted in consumer responses that were comparable or superior to consumer responses for psoas major samples. Similarly, enhancing GM steaks resulted in consumer responses that were comparable or superior to nonenhanced LL samples. Consumers reacted least favorably to nonenhanced Australian grass-fed beef as they rated all palatability traits lowest (P < 0.05) for both LL and GM samples. However, enhancing grassfed beef resulted in consumer responses that were similar (P > 0.05) to nonenhanced grain-fed beef. This response to enhancement was observed in consumer scores for both LL and GM samples. Consumers could not detect differences (P > 0.05) in tenderness, juiciness, flavor, overall liking, or satisfaction between grain-fed beef from Australia and the US

Bovine Somatotropin Alters Myosin Heavy Chains and Beta Receptors in Skeletal Muscle of Feedlot Heifers with Little Impact on Live or Carcass Performance

The objective was to determine whether recombinant bovine somatotropin (rbST) enhanced live performance,skeletal muscle biological activity, and beta-adrenergic receptor expression of feedlot heifers during the finishing phase. Heifers (n = 16; initial body weight = 457 ± 3 kg) were randomly assigned to pens (4 pens/treatment; 2 heads/pen) and treatment: (1) no rbST (Control); (2) 500 mg/hd of sometribove zinc at day 0 and 14 (rbST; Posilac®; Elanco AnimalHealth, Greenfield, IN). Longissimus muscle biopsies for muscle chemistry were collected on day 0, 14, 28, 42, and 56. The rbST heifers had increased expression of AMP-activated protein kinase alpha and beta 3 adrenergic receptor (P < 0.05). Day of the study affected the expression of myosin heavy chain-IIA (MHC-IIA), MHC-IIX, beta 2 adrenergic receptor, peroxisome proliferator-activated receptor gamma, and stearoyl-CoA desaturase (P < 0.05). Day had a significant effect on muscle fiber cross-sectional area and proportion (P < 0.05). As days on feed increased, the area of MHC-I fibers decreased whereas MHC-IIA and IIX area increased (P < 0.05). The rbST heifers had decreased proportions of MHC-I fibers and increased proportions of MHC-IIX fibers (P < 0.05). The greatest density of Paired Box 7-positive cells was on day 0, 28, and 42 (P < 0.05), and the greatest density of Myogenic factor 5-positive cells was on day 42 and 56 (P < 0.05). Also, the greatest density of cells positive for Paired Box 7:Myogenic factor 5 was measured on day 28 (P < 0.05). These data indicate that, as days on feed increase, the effects of skeletal muscle biological activity are not dependent on rbST administration but may be more due to physiological changes occurring as the animal reaches physio-logical maturity

Palatability and Predator Avoidance Behavior of Salamanders in Response to the Virginia Opossum (Didelphis Virginiana)

Our understanding of mammalian predation on salamanders is primarily restricted to small carnivorous species (i.e., shrews). We conducted a series of investigations to determine whether the Virginia opossum (Didelphis virginiana) is a predator of various salamander species [Desmognathus fuscus, Plethodon dorsalis, and Notophthalmus viridescens (adult and eft)] from the eastern United States. All species, including toxic newt efts, were palatable to opossums. These results suggest opossums could be an active predator of salamanders. In a second study, each terrestrial salamander species exhibited avoidance responses to kairomones from opossums indicating that despite a significant risk of mortality each salamander has evolved mechanisms to minimize predation risk. Combined with overlapping habitat preferences, foraging behavior that places them in contact, and a dietary preference for animal matter, these data suggest opossums may be an important predator on terrestrial salamanders

Only Fear the Fatal Foe: Predation Risk Assessment by eastern newts (Notophthalmus viridescens) in Response to Common Snapping Turtles and Other Potential Predators

Many organisms utilize toxic or noxious compounds as a means of deterring predation. Eastern newts (Notopthalmus viridescens), along with other species in the family Salamandridae, possess a potent neurotoxin called tetrodotoxin (TTX). Although TTX can serve as an effective antipredator mechanism in species of newts with high concentrations (e.g., Taricha), eastern newts have relatively low levels of toxicity in comparison to those species, and it may not serve as an effective antipredator mechanism against all threats. In this case, they may benefit rather by utilizing behavioral changes to avoid initial contact with predators. We tested for predator-avoidance behavior in newts by exposing individuals to kairomones from various predators. We recorded activity patterns of newts when they were exposed to cues from potential predators including bullfrogs (Lithobates catesbeiana), water snakes (Nerodia sipedon) and snapping turtles (Chelydra serpentina), as well as a non-predator (bullfrog tadpoles), and a control (deionized water). Newts reduced activity when exposed to snapping turtle stimuli, but did not change activity when exposed to any other chemical cues. We verified that newts interact with this predator by trapping snapping turtles found in ponds from which newts were collected. Finally, we used turtles caught during this sampling to test whether they are an actual predator of newts and whether newts shift microhabitat use when exposed to this predator. In each replicate, turtles consumed newts, and newts spatially avoided the snapping turtle, relative to a control. The results of these experiments indicate newts rely on predator-avoidance behavior to reduce the probability of being consumed by snapping turtles, but do not reduce activity in response to other potential predators that may only consume them rarely

Whole-genome sequencing reveals host factors underlying critical COVID-19

Altres ajuts: Department of Health and Social Care (DHSC); Illumina; LifeArc; Medical Research Council (MRC); UKRI; Sepsis Research (the Fiona Elizabeth Agnew Trust); the Intensive Care Society, Wellcome Trust Senior Research Fellowship (223164/Z/21/Z); BBSRC Institute Program Support Grant to the Roslin Institute (BBS/E/D/20002172, BBS/E/D/10002070, BBS/E/D/30002275); UKRI grants (MC_PC_20004, MC_PC_19025, MC_PC_1905, MRNO2995X/1); UK Research and Innovation (MC_PC_20029); the Wellcome PhD training fellowship for clinicians (204979/Z/16/Z); the Edinburgh Clinical Academic Track (ECAT) programme; the National Institute for Health Research, the Wellcome Trust; the MRC; Cancer Research UK; the DHSC; NHS England; the Smilow family; the National Center for Advancing Translational Sciences of the National Institutes of Health (CTSA award number UL1TR001878); the Perelman School of Medicine at the University of Pennsylvania; National Institute on Aging (NIA U01AG009740); the National Institute on Aging (RC2 AG036495, RC4 AG039029); the Common Fund of the Office of the Director of the National Institutes of Health; NCI; NHGRI; NHLBI; NIDA; NIMH; NINDS.Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care or hospitalization after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes-including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)-in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease