Prevalence of antibodies against feline panleukopenia virus in client-owned cats in Southern Germany

Feline panleukopenia is a frequent and commonly fatal disease of cats. Recent published studies have raised suspicions that some cats fail to develop antibodies after vaccination. The purpose of this study was to assess the prevalence of antibodies against feline panleukopenia virus (FPV) in cats in Southern Germany, and to identify factors that are associated with a lack of antibodies. In total, 350 cats presented to the Clinic of Small Animal Medicine, Ludwig-Maximilians-Universitaet were randomly included in the study. Information regarding signalment, origin, environment, lifestyle, housing conditions, health status, chronic diseases, glucocorticoid therapy, and vaccination status were collected. Antibodies were detected by haemagglutination inhibition test. Asymptomatic chi-squared tests and univariable logistic regression were used to investigate associations between a lack of antibodies and the different variables. Associations determined to be statistically significant at P < 0.1 were verified by a multivariable logistic regression analysis.Of the 350 cats, 103 (29.4%) had no antibodies against FPV. Chronic kidney disease, neoplasia, glucocorticoid therapy, and vaccination status were significantly associated with a lack of antibodies. The cats with no antibodies were likely to have inadequate immunity against panleukopenia and those with chronic diseases or receiving glucocorticoids were less likely to be protected.     

Increased CO2 emission and organic matter decomposition by leaf-cutting ant nests in a coastal environment

Leaf-cutting ants perform a vital role in the cycling of carbon and nutrients in tropical ecosystems. Nests have high levels of organic matter and refuse dumps host up to two times more soil micro-organisms than non-nest soil. The increased levels of organic matter in the soil of nests, however, can affect CO₂ emissions from soil and alter the balance of atmospheric CO₂. We aimed at assessing the effect of nests of the leaf-cutting ant Acromyrmex balzani on CO₂ emissions in a coastal area of Northeast Brazil. Results show that A. balzani nests emitted up to four times more CO₂ than the surrounding soil and emissions were positively correlated with soil moisture and soil organic matter (SOM) content. In addition, field experiments demonstrated that refuse material has a lower residence time than the leaf material brought to the colonies. Despite the high density of nests and high content of SOM compared to adjacent control soil, CO₂ emissions by A. balzani nests represent only 0.3% of the total CO₂ efflux by the studied ecosystem. Although these effluxes account for a relative small portion of the total soil CO₂ emission, they are still important for the understanding of C balance, especially when one considers the thousands of tons of CO₂ emitted each day, across entire Neotropical regions where leaf-cutting ants occur.     

DNA barcoding reveals blend of silver catfish Rhamdia species from fish farms in Southern Brazil

Rhamdia quelen is the most produced native freshwater fish in fish farms in South Brazil. Until recently, Rhamdia branneri and Rhamdia voulezi were synonyms of R. quelen, and all the species are commercialized as silver catfish (locally called jundiá or bagre sapo) by the aquaculture industry. In fact, because these species are morphologically very similar, interspecific crosses easily might occur in fish farming. We employed standard DNA barcoding to identify jundiá molecular operational taxonomic units (MOTUs) in fish cultivated and commercialized in the industry and in possible escapees in the natural environment in southern Brazil. We analysed 48 individuals from six fish farms and 48 individuals from three rivers (Uruguay, Benedito Novo and Itapocu Rivers) using the mitochondrial cytochrome oxidase subunit I (COI). Four MOTUs were identified based on the estimated optimum threshold (OT = 0.77), and these MOTUs were concordant with Bayesian Inferece (BI) and Neighbour‐Joining (NJ) trees. Our results support the existence of at least three species in our dataset: R. branneri, R. voulezi, and R. quelen 1 and R. quelen 2. The interspecific genetic divergence ranged from 1.1% to 5.1% (mean = 3.5%), and the intraspecific distance ranged from 0% to 1.4% (mean = 0.24%). The presence of cultivated fish in the Uruguay and Benedito Novo Rivers provides evidence of genetic contamination in native populations. These results show the need to regulate aquaculture activities and to characterize the species and commercial lineages of silver catfish that are cultivated in South Brazil.     

An architectural framework that may lie at the core of the postsynaptic density

The postsynaptic density (PSD) is a complex assembly of proteins associated with the postsynaptic membrane that organizes neurotransmitter receptors, signaling pathways, and regulatory elements within a cytoskeletal matrix. Here we show that the sterile alpha motif domain of rat Shank3/ProSAP2, a master scaffolding protein located deep within the PSD, can form large sheets composed of helical fibers stacked side by side. Zn2+, which is found in high concentrations in the PSD, binds tightly to Shank3 and may regulate assembly. Sheets of the Shank protein could form a platform for the construction of the PSD complex.     

Fish assemblages in Atlantic Forest streams: the relative influence of local and catchment environments on taxonomic and functional species

Streams are under environmental pressures acting at different scales that influence the ecological organisation of their fish assemblages. However, the relative influence of the different scale‐related variables on assemblage composition and function is poorly understood. We evaluated the importance of local‐ and catchment‐scale environmental variables, as well as the spatial structure of the sampling sites, in shaping fish assemblages in Atlantic Forest streams. Local‐scale variables were those measured at the sampling sites, describing the local habitat conditions (e.g. depth, substrate type, altitude). Catchment‐scale variables were those integrating the upstream landscape of the sampling sites (e.g. catchment land use). Spatial distances were calculated from watercourse distance using principal coordinates of neighbour matrices. Altogether, 28 local and seven catchment variables were initially subjected to two processes of eliminating co‐linearity. Redundancy analysis was applied to the three matrices (spatial, local and catchment) to quantify the variance in the structure of the fish assemblages explained by each matrix. Local variables explained more variability in both taxonomic and functional assemblage structure, than catchment and spatial variables. Local variables also changed along the longitudinal gradient, which consequently influenced fish assemblage structure. This pattern was also influenced by anthropogenic alteration and non‐native species, which were more abundant in downstream sites. These results highlight the need to assess Atlantic Forest streams under different environmental scales, especially through the use of quantitative local‐scale metrics, and to consider the effects of longitudinal patterns in structuring fish assemblages when developing and implementing monitoring programmes, impact studies and conservation plans.     

Ecological drivers of fish metacommunities: Environmental and spatial factors surpass predation in structuring metacommunities of intermittent rivers

Metacommunity theory is a new approach for explaining how local and regional processes contribute to community organisation and integrative studies are needed to fully characterise the processes underlying its structure and function. We analysed, through variation partitioning and distance decay relationships, how metacommunities of fish in pools of intermittent rivers are structured by environmental, species interaction and spatial factors. The results indicate that both species sorting and dispersal limitation (spatial factors) were important in shaping fish metacommunities. Species sorting was the most influential driver within fish metacommunities, but predation was much less relevant and did not show any pure effect in metacommunity structure. However, environmental factors were determinant among metacommunity patches.