Modulations of lipid metabolism and development of the Atlantic salmon (Salmo salar) fry in response to egg-to-fry rearing conditions

In stocking program, the use of artificial incubation conditions in hatcheries from the fertilisation of eggs to the release of unfed fry could reduce their ability to adapt to the natural environment. This study evaluates the effects of three factors on the fitness and physiology of salmon fry at their emergence, the origin of water (river vs drilling), the type of support in the incubator (support matrix vs plastic sheets) and the type of incubators (Californian vs vertical trays), and compares them to a semi-natural incubation method in river. Key biological functions including nutritional and immune status were compared among experimental conditions using biometric parameters, lipid composition and gene expression analyses. Our findings demonstrated that fry incubated in vertical trays supplied with river water had no significant difference in growth and lipid composition compared to those in semi-natural incubators. Besides, fry incubated on a substrate matrix in Californian trays exhibited phenotypic characteristics closest to those incubated in river. This support matrix improved fish growth, lipid consumption and distribution compared to fry on plastic sheets. Moreover, the large amounts of several PUFAs in these fry could allow a better membrane fluidity ensuring a better adaptation to temperature variation under cold conditions. In addition, drilling water improved the survival rate compared to river water due to lower numbers of fine particles, known to be responsible for the clogging of eggs. To conclude, using a substrate combined with drilling water in artificial incubators could increase fry fitness and its adaption to wild life.

     

Using occupancy models of forest breeding birds to prioritize conservation planning

As urban development continues to encroach on the natural and rural landscape, land-use planners struggle to identify high priority conservation areas for protection. Although knowing where urban-sensitive species may be occurring on the landscape would facilitate conservation planning, research efforts are often not sufficiently designed to make quality predictions at unknown locations. Recent advances in occupancy modeling allow for more precise estimates of occupancy by accounting for differences in detectability. We applied these techniques to produce robust estimates of habitat occupancy for a subset of forest breeding birds, a group that has been shown to be sensitive to urbanization, in a rapidly urbanizing yet biological diverse region of New York State. We found that detection probability ranged widely across species, from 0.05 to 0.8. Our models suggest that detection probability declined with increasing forest fragmentation. We also found that the probability of occupancy of forest breeding birds is negatively influenced by increasing perimeter-area ratio of forest fragments and urbanization in the surrounding habitat matrix. We capitalized on our random sampling design to produce spatially explicit models that predict high priority conservation areas across the entire region, where interior-species were most likely to occur. Finally, we use our predictive maps to demonstrate how a strict sampling design coupled with occupancy modeling can be a valuable tool for prioritizing biodiversity conservation in land-use planning.     

No signs of thermal acclimation of heterotrophic respiration from peat soils exposed to different water levels

In a mesocosm experiment, with bare peat soils exposed to different water levels (WL), we examined whether heterotrophic respiration (R_h) acclimated to a 3 ^°C temperature increase. Across all WLs, R_h at 15 ^°C was never lower in the heated treatment than in the unheated treatment, indicating that R_h did not acclimate to the warmer conditions. We hypothesize that this lack of thermal acclimation is due to the unlimited substrate availability in these organic soils. These results imply that peat soils may exhibit a sustained positive feedback to global warming.     

Litter contribution to diurnal and annual soil respiration in a tropical montane cloud forest

Respiration of CO₂ from soils (R_s) is a major component of the carbon cycle of ecosystems, but understanding is still poor of both the relative contributions of different respiratory sources to R_s, and the environmental factors that drive diurnal variations in R_s. We measured total and litter-free R_s at half-hourly intervals over full 24 h periods, and thereafter twice a month for 10 months in a tropical montane cloud forest (TMCF) in Peru. Total R_s declined by about 61% during the night as a result of variations in respiration rate in the litter, which were partly correlated with the soil surface air temperature. Most of the diurnal variation of R_s in this TMCF appears to be driven by respiration in the litter layer, which contributed 37% to the total soil CO₂ efflux. Total R_s rates at this particular site would have been overestimated by 60% if derived from daytime measurements that had not been corrected for diurnal variations in R_s.     

Assessing the Sensitivity of Quantitative Structural Activity Analysis Models for Evaluating New Military Compounds

Quantitative structural activity relationship (QSAR) models are receiving wide use because of new regulations and public scrutiny regarding new compounds entered into commerce. Accordingly, the US Department of Defense (DoD) supported this study to evaluate QSAR modeling for energetic compounds. Four compounds proposed to replace ammonium perchlorate were examined: ammonium di(nitramido)amine (ADNA); 1,3,5,5-tetranitrohexahydropyrimidine (DNNC); 1,3,3,5,7,7-hexanitro-1,5-diazacyclooctane (HCO); and diammonium di(nitramido)dinitroethylene (ADNDNE). Currently used compounds were evaluated as analogues for those under development. Ammonium dinitramide (ADN) was the analogue for ADNA; hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) for DNNC; octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) for HCO; and 1,1-diamino-2,2-dinitroethene (FOX-7) for ADNDNE. QSAR analysis was performed with the US Environmental Protection Agency’s Estimation Program Interface (EPI) Suite?. The comparison of model estimates to literature values ranged from good-to-poor. Results suggested the proposed replacement compounds have low aquatic toxicities and little potential to bioaccummulate, but the uncertainty in the predictions indicates QSAR modeling with EPI Suite? is only useful for qualitative assessments of these proposed energetic compounds.     

Single-molecule lysozyme dynamics monitored by an electronic circuit

Tethering a single lysozyme molecule to a carbon nanotube field-effect transistor produced a stable, high-bandwidth transducer for protein motion. Electronic monitoring during 10-minute periods extended well beyond the limitations of fluorescence techniques to uncover dynamic disorder within a single molecule and establish lysozyme as a processive enzyme. On average, 100 chemical bonds are processively hydrolyzed, at 15-hertz rates, before lysozyme returns to its nonproductive, 330-hertz hinge motion. Statistical analysis differentiated single-step hinge closure from enzyme opening, which requires two steps. Seven independent time scales governing lysozyme's activity were observed. The pH dependence of lysozyme activity arises not from changes to its processive kinetics but rather from increasing time spent in either nonproductive rapid motions or an inactive, closed conformation.     

Characterization of pruritus in canine atopic dermatitis,flea bite hypersensitivity and flea infestation and its role in diagnosis

Background – In dogs, flea infestation (FI), flea bite hypersensitivity (FBH) and canine atopic dermatitis (CAD) have been mainly characterized by their lesions but never by their pruritus. In clinical practice, many of these dogs exhibit only pruritus. Hypothesis/Objectives – The purpose of this study was to evaluate the characteristics of pruritus in these dermatoses and their potential usefulness for diagnosis. Animals – Dogs included were selected from the Oniris clinical data. Cases were selected in which the dogs had only one of the three dermatoses diagnosed. The diagnosis of CAD was based on Prélaud’s criteria and positive intradermal tests except flea; for FBH by compatible clinical signs and a response to an intradermal test with flea allergen; and for FI by the presence of fleas. Moreover, in each group, other primary pruritic skin diseases were excluded. Methods – Location, behavioural manifestations, seasonality and quantification of the pruritus were evaluated. The statistical analysis used chi‐squared test with a P‐value <0.05. Results – Three hundred and forty‐six dogs were analysed, 91 with CAD, 110 FI and 145 FBH. The period (season) of onset was not statistically different either for each dermatosis or among the three dermatoses. Some locations were highly specific for one dermatosis as follows: ventral abdomen/medial surface of thigh (chewing) and radius/carpus/tibia/tarsus (chewing) in FI; back/dorsolumbar area (chewing) and tail (chewing) in FBH; and paws (chewing/licking) and face/neck (rubbing) in CAD. Conclusions and clinical importance – Some features of pruritus could be suggestive of the causal disease, with possible diagnostic value in pruritic dogs.     

Expression of human CD46 has no effect on porcine circovirus type 2 infection and shedding in the experimental pig model

Xenotransplantation of tissues from transgenic pigs with desired genetic modifications such as CD46 expression help minimize xenograft rejections. However, CD46 is a known receptor for some viruses. In this study, pigs transgenic for human CD46 (CD46-TG) and appropriate non-transgenic (non-TG) control pigs were utilized to determine possible differences in the level of replication and shedding of porcine circovirus type 2 (PCV2). Non-TG and CD46-TG were blocked by transgenic status and randomly divided into three groups: Non-TG negative controls (n?=?3), non-TG-PCV2 (n?=?10; PCV2a?=?5, PCV2b?=?5), and CD46-TG-PCV2 (n?=?6; PCV2a?=?3, PCV2b?=?3). Blood, oral, nasal and fecal swabs were collected at regular intervals from the day of arrival until 70 days post inoculation (DPI). All samples were tested by quantitative real-time PCR for the presence of PCV2 DNA and serum was tested for presence of PCV2 antibodies by ELISA. Overall, the main effects "transgenic status" and "PCV2 subtype" had no influence on degree of PCV2 viremia and shedding or the anti-PCV2 humoral immune response in CD46-TG-PCV2 pigs compared to non-TG-PCV2 pigs. Differences in PCV2 concentrations between non-TG-PCV2 and CD46-TG-PCV2 pigs were minimal and limited to DPI 35 in sera, DPI 7 in fecal swabs and DPI 5 in nasal swabs when CD46-TG-PCV2 pigs had significantly higher concentrations of PCV2 DNA. At DPI 1, CD46-TG-PCV2 pigs had significantly lower concentrations of PCV2 DNA in oral swabs. Under the study conditions, the presence of human CD46 in transgenic pigs had no effect on PCV2 infection in otherwise healthy pigs capable of a normal immune response.