Mortality threshold for juvenile Chinook salmon (Oncorhynchus tshawytscha) in an epidemiological model of Ceratomyxa shasta

The myxozoan parasite, Ceratomyxa shasta, is the most significant pathogen of juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Klamath River, CA, USA. This parasite requires two hosts - a freshwater polychaete (Manayunkia speciosa) and a salmonid - to complete its life cycle. The complex life cycle and large geographic area where infection occurs make monitoring and managing the disease, ceratomyxosis, difficult. Epidemiological models are helpful tools to examine complex disease systems as they serve to identify parameters and rank their relative importance. A system of equations is used to derive the basic reproductive number (Ro) of the parasite. In this paper we present a model for ceratomyxosis induced mortality in Chinook salmon. The field experiments described herein quantify the mortality threshold (a critical parameter in the model), by exposing native Chinook salmon to C. shasta in the Klamath River. The average percent mortality that resulted from this challenge ranged from 2.5% to 98.5% over an exposure dose of 4.4 - 612 x 106 parasites. This study identified a non-linear mortality threshold for Iron Gate Hatchery (IGH) Chinook salmon that ranged from 5.6 - 9.9 x 104 total parasites. Below this threshold no mortality occurs, yet above it mortality dramatically increases. This threshold provides a target to reduce parasitism in emigrating juvenile Chinook salmon

Using Emerging Technologies to Bolster Long-Term Monitoring of Wetlands

Freshwater wetlands support a disproportionately high diversity of species relative to other ecosystems and they are particularly vulnerable to climate change. Across Grand Teton and Yellowstone National Parks, wetlands represent just 3% of the landscape, yet 70% of Wyoming bird species and all native amphibians in the region use wetlands for some stage of their life. The Greater Yellowstone Inventory and Monitoring Network has monitored amphibians in wetlands since 2006 and found that over 40% of the region’s isolated wetlands are dry in years with above average temperatures and reduced precipitation. Adding novel technologies to these monitoring efforts will increase our understanding of species diversity in wetlands susceptible to drying. We outfitted three wetland sites in Grand Teton National Park with acoustic (i.e., audible and ultrasonic) monitoring technology and wildlife camera traps in summer 2016. We collected data over a four-week period to test the efficacy of automated technology for wetland monitoring. Based on preliminary results from the ultrasonic monitoring and wildlife cameras, we detected four times more species with these tools, when compared to visual surveys of amphibians alone. Additionally, automated methods allowed us to detect species over a longer time window than feasible with visual surveys. We will continue our work in 2017, using environmental DNA, acoustic monitoring, and wildlife camera traps to capture information about a broader diversity of taxa using wetlands, to expand and enrich current monitoring efforts

Relationship Between Temperature and Ceratomyxa shasta–Induced Mortality In Klamath River Salmonids

Water temperature influences almost every biological and physiological process of salmon, including disease resistance. In the Klamath River (California), current thermal conditions are considered sub-optimal for juvenile salmon. In addition to borderline temperatures, these fish must contend with the myxozoan parasite Ceratomyxa shasta, a significant cause of juvenile salmonid mortality in this system. This paper presents 2 studies, conducted from 2007 to 2010, that examine thermal effects on C. shasta induced mortality in native Klamath River Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon. In each study, fish were exposed to C. shasta in the Klamath River for 72 hr and then reared in the laboratory under temperature-controlled conditions. The first study analyzed data collected from a multi-year monitoring project to asses the influence of elevated temperatures on parasite-induced mortality during the spring/summer migration period. The second study compared disease progression in both species at 4 temperatures (13, 15, 18, and 21 C) representative of spring/summer migration conditions. Both studies demonstrated that elevated water temperatures consistently resulted in higher mortality and faster mean days to death. However, analysis of data from the multi-year monitoring showed that the magnitude of this effect varied among years and was more closely associated with parasite density than with temperature. Also, there was a difference in the timing of peak mortality between species; Chinook incurred high mortalities in 2008 and 2009, whereas coho was greatest in 2007 and 2008. As neither temperature nor parasite density can be easily manipulated, management strategies should focus on disrupting the overlap of this parasite and its obligate hosts to improve emigration success and survival of juvenile salmon in the Klamath River.Keywords: Rainbow trout, Water temperature, Myxozoa, Myxosporean parasite, Coho salmon, Steelhead, California, Assay, Chinook salmo

Kinetic Heterogeneities in a Highly Supercooled Liquid

We study a highly supercooled two-dimensional fluid mixture via molecular dynamics simulation. We follow bond breakage events among particle pairs, which occur on the scale of the $\alpha$ relaxation time $\tau_{\alpha}$. Large scale heterogeneities analogous to the critical fluctuations in Ising systems are found in the spatial distribution of bonds which are broken in a time interval with a width of order $0.05\tau_{\alpha}$. The structure factor of the broken bond density is well approximated by the Ornstein-Zernike form. The correlation length is of order $100 \sigma_1$ at the lowest temperature studied, $\sigma_1$ being the particle size. The weakly bonded regions thus identified evolve in time with strong spatial correlations.Comment: 3 pages, 6 figure

Effect of local environment and stellar mass on galaxy quenching and morphology at 0.5<z<2.00.5<z<2.0

We study galactic star-formation activity as a function of environment and stellar mass over 0.5<z<2.0 using the FourStar Galaxy Evolution (ZFOURGE) survey. We estimate the galaxy environment using a Bayesian-motivated measure of the distance to the third nearest neighbor for galaxies to the stellar mass completeness of our survey, $\log(M/M_\odot)>9 (9.5)$ at z=1.3 (2.0). This method, when applied to a mock catalog with the photometric-redshift precision ($\sigma_z / (1+z) \lesssim 0.02$), recovers galaxies in low- and high-density environments accurately. We quantify the environmental quenching efficiency, and show that at z> 0.5 it depends on galaxy stellar mass, demonstrating that the effects of quenching related to (stellar) mass and environment are not separable. In high-density environments, the mass and environmental quenching efficiencies are comparable for massive galaxies ($\log (M/M_\odot)\gtrsim$ 10.5) at all redshifts. For lower mass galaxies ($\log (M/M)_\odot) \lesssim$ 10), the environmental quenching efficiency is very low at $z\gtrsim$ 1.5, but increases rapidly with decreasing redshift. Environmental quenching can account for nearly all quiescent lower mass galaxies ($\log(M/M_\odot) \sim$ 9-10), which appear primarily at $z\lesssim$ 1.0. The morphologies of lower mass quiescent galaxies are inconsistent with those expected of recently quenched star-forming galaxies. Some environmental process must transform the morphologies on similar timescales as the environmental quenching itself. The evolution of the environmental quenching favors models that combine gas starvation (as galaxies become satellites) with gas exhaustion through star-formation and outflows ("overconsumption"), and additional processes such as galaxy interactions, tidal stripping and disk fading to account for the morphological differences between the quiescent and star-forming galaxy populations.Comment: 29 pages, 15 figure, accepted for publication in Ap

A Brief Smoking Cessation Intervention for Heavy Drinking Smokers: Treatment Feasibility and Acceptability

Approximately 20–25% of regular smokers report heavy drinking. Abstinent smokers are five times as likely to experience a smoking lapse during drinking episodes. Current efforts seek to improve treatments for this subgroup of heavy-drinking smokers. This study tested the feasibility and acceptability of addressing alcohol use in a brief, single session smoking cessation intervention (SMK+A) compared to smoking cessation counseling only (SMK); these interventions were grounded in a motivational interview framework and included personalized feedback, decisional balance, quit day setting, and tailored skills building (e.g., breathing techniques, coping with urges, dealing with social pressures) to maintain abstinence. Descriptive outcomes included reported helpfulness of intervention skills, readiness to change scores, and feasibility of participant recruitment and retention. We also assessed 7-day point prevalence of smoking cessation, and smoking and drinking reduction at 1-month follow-up. Participants (N = 22) were community-based treatment-seeking daily smokers (≥5 cigarettes/day) who were also heavy drinkers (≥14 drinks/week for men, ≥ 7 drinks/week for women; or ≥5 drinks on one episode in past week for men, ≥4 for women). Twenty five percent of interested individuals were eligible after initial phone screen, and all randomized participants were retained through follow up. All skills demonstrated high acceptability (i.e., rated between moderately and very helpful), and a significant proportion of participants in each condition reported taking action to reduce cigarette smoking and/or alcohol use at 1-month post-quit. Three participants in each condition (27.3%) attained bioverified (CO ≤ 4 parts per million and cotinine ≤ 3 ng/mL) smoking quit at follow-up. Given the modified intervention's acceptability and flexibility, larger studies may help to elucidate this intervention's effects on readiness to change, smoking cessation, and alcohol reduction

Increased TNF-α/IFN-γ/IL-2 and Decreased TNF-α/IFN-γ Production by Central Memory T Cells Are Associated with Protective Responses against Bovine Tuberculosis Following BCG Vaccination

Central memory T cells (Tcm) and polyfunctional CD4 T cell responses contribute to vaccine-elicited protection with both human and bovine tuberculosis (TB); however, their combined role in protective immunity to TB is unclear. To address this question, we evaluated polyfunctional cytokine responses by CD4 T cell effector / memory populations from bacille Calmette Guerin (BCG) vaccinated and non-vaccinated calves prior to and after aerosol challenge with virulent Mycobacterium bovis. Polyfunctional cytokine expression patterns in the response by Tcm, effector memory, and effector T cell subsets were similar between BCG-vaccinated and M. bovis-infected calves; only differing in magnitude (i.e., infected > vaccinated). BCG vaccination, however, did alter the kinetics of the ensuing response to virulent M. bovis infection. Early after challenge (three weeks post-infection), non-vaccinates had greater antigen-specific IFN-γ/TNF-α and lesser IFN-γ/TNF-α/IL-2 responses by Tcm cells than did vaccinated animals. Importantly, these differences were also associated with mycobacterial burden upon necropsy. Polyfunctional responses to ESAT-6:CFP10 (antigens not synthesized by BCG strains) were detected in memory subsets, as well as in effector cells, as early as three weeks after challenge. These findings suggest that cell fate divergence may occur early after antigen priming in the response to bovine TB and that memory and effector T cells may expand concurrently during the initial phase of the immune response. In summary, robust IFN-γ/TNF-α response by Tcm cells is associated with greater mycobacterial burden while IFN-γ/TNF-α/IL-2 response by Tcm cells are indicative of a protective response to bovine TB

The effect of irrigation on cadmium, uranium, and phosphorus contents in agricultural soils

Cadmium (Cd) is a toxic metal which has accumulated in New Zealand agricultural soils due to phosphate fertilizer application. Understanding the contribution of plant uptake or leaching of Cd to observed Cd losses from soil is important. The concentration and distribution of Cd in irrigated and unirrigated soils with the same phosphate fertilizer history were investigated. Twenty-two pairs of soil samples from four depths (0–0.1, 0.1–0.2, 0.2–0.3 and 0.3–0.4 m) were taken from irrigated and unirrigated areas in the same field on dairy farms in three regions of New Zealand. The mean concentration of Cd at depths of 0–0.1 m and 0.1–0.2 m, as well as the cumulative masses of Cd (0–0.2, 0–0.3 and 0–0.4 m) in unirrigated soils were significantly higher (P < 0.05) than in irrigated soils. The concentration of phosphorus (P) at all depths (except for 0.2–0.3 m), as well as the cumulative mass of P in all depths of unirrigated soils, was also significantly higher (P < 0.05) than irrigated soils. However, no significant difference was detected in the concentrations of uranium (U) between irrigated and unirrigated soils. Irrigation induced a ∼7% Cd loss from topsoil (0–0.1 m), with the average rate of Cd loss from the top 0.1 m (due to irrigation) being 2.3 g ha⁻¹ yr⁻¹. This study therefore confirms that irrigation can enhance Cd mobilization, however Cd is mainly adsorbed to the surface soil

The transcriptional repressor protein NsrR senses nitric oxide directly via a [2Fe-2S] cluster

The regulatory protein NsrR, a member of the Rrf2 family of transcription repressors, is specifically dedicated to sensing nitric oxide (NO) in a variety of pathogenic and non-pathogenic bacteria. It has been proposed that NO directly modulates NsrR activity by interacting with a predicted [Fe-S] cluster in the NsrR protein, but no experimental evidence has been published to support this hypothesis. Here we report the purification of NsrR from the obligate aerobe Streptomyces coelicolor. We demonstrate using UV-visible, near UV CD and EPR spectroscopy that the protein contains an NO-sensitive [2Fe-2S] cluster when purified from E. coli. Upon exposure of NsrR to NO, the cluster is nitrosylated, which results in the loss of DNA binding activity as detected by bandshift assays. Removal of the [2Fe-2S] cluster to generate apo-NsrR also resulted in loss of DNA binding activity. This is the first demonstration that NsrR contains an NO-sensitive [2Fe-2S] cluster that is required for DNA binding activity

Low levels of nucleotide diversity in Crocodylus moreletii and evidence of hybridization with C. acutus

Examinations of both population genetic structure and the processes that lead to such structure in crocodilians have been initiated in several species in response to a call by the IUCN Crocodile Specialist Group. A recent study used microsatellite markers to characterize Morelet\u27s crocodile (Crocodylus moreletii) populations in north-central Belize and presented evidence for isolation by distance. To further investigate this hypothesis, we sequenced a portion of the mitochondrial control region for representative animals after including samples from additional locales in Belize, Guatemala and Mexico. While there is limited evidence of subdivision involving other locales, we found that most of the differentiation among populations of C. moreletii can be attributed to animals collected from a single locale in Belize, Banana Bank Lagoon. Furthermore, mitochondrial DNA sequence analysis showed that animals from this and certain other locales display a haplotype characteristic of the American crocodile, C. acutus, rather than C. moreletii. We interpret this as evidence of hybridization between the two species and comment on how these new data have influenced our interpretation of previous findings. We also find very low levels of nucleotide diversity in C. moreletii haplotypes and provide evidence for a low rate of substitution in the crocodilian mitochondrial control region. Finally, the conservation implications of these findings are discussed