Biomass production of Lolio‐Cynosuretum grassland is not increased by plant‐species richness

In experimental grasslands, a positive relationship between biomass production and plant diversity has often been found. Here, we compared a moderately species‐rich old sward with its grass‐dominated counterpart (12 vs. 8 species per 2.5 m², or 8.3 vs. 0.7% yield proportion of dicots at the start of the experiment) established by herbicide application. We hypothesized an increased N, P and K uptake in the diverse sward related to a higher colonization rate with arbuscular mycorrhizal fungi (AMF), the presence of legumes, and complementary nutrient use of plant species. Phosphorus or N fertilizer application (according to contributions of AMF or legumes) were expected to balance the assumed smaller biomass production of the grass compared to the diverse sward. In two experimental years, N, P and K uptake, biomass production, N₂ fixation, and intra‐ and extraradical AMF colonization were investigated in an untreated control and plots that were fertilized with P and N in a low (P1: 20 kg P ha^?1; N1: 50 kg N ha^?1) or a high dose (P2: 100 kg P ha^?1; N2: 500 kg N ha^?1) in both swards. Biomass production was larger in the grass compared to the diverse sward. The N, P and K uptake, accumulated over three harvests (or 1.5 years), was also larger in the grass sward. The biomass production ranged from 5.3 to 10.0 t ha^?1 and accumulated nutrient uptake from 82 to191 kg N ha^?1, 19 to 31 kg P ha^?1 and 112 to 221 kg K ha^?1. Small legume proportions resulted in an accumulated N₂ fixation between 0 and 3 kg ha^?1. In the second year, the root length colonized with AMF structures was larger in the diverse compared to the grass sward, and the root length colonized with arbuscules and coils was larger in the N2 treatment compared to the control in the diverse sward. There were hints to higher AMF abundance under conditions of limited P availability (low soil P content, high N:P ratio in plant biomass). We conclude that in semi‐natural grassland of moderate species richness several factors may affect the relationship between plant diversity and productivity, i.e., management, plant species identity, and the number of the plant species of the low‐diversity level.     

Calcific band keratopathy in an alpaca

A 4‐year‐old female Suri alpaca was presented for evaluation of acute onset weakness, lethargy, and recent development of opacities in both eyes. On ophthalmic examination, bilaterally symmetrical corneal opacities were noted along the interpalpebral fissures with a few corneal blood vessels intermingled. A presumed diagnosis of calcific band keratopathy was made based on location and appearance. The patient was euthanized a short while after diagnosis due to reasons unrelated to the eyes and histologic examination of the corneas revealed subepithelial calcium and vascularization, consistent with calcific band keratopathy. This case report is the first to document this ocular condition in an alpaca.     

Effect of Primula root and other plant extracts on infection structure formation of Phyllosticta ampelicida (asexual stage of Guignardia bidwellii) and on black rot disease of grapevine in the greenhouse

Journal of Plant Diseases and Protection - The paper describes in vitro and in vivo experiments with extracts from Primula root and Hedera helix aimed at characterizing their effect on Phyllosticta...     

Energy uptake and allocation during ontogeny

All organisms face the problem of how to fuel ontogenetic growth. We present a model, empirically grounded in data from birds and mammals, that correctly predicts how growing animals allocate food energy between synthesis of new biomass and maintenance of existing biomass. Previous energy budget models have typically had their bases in rates of either food consumption or metabolic energy expenditure. Our model provides a framework that reconciles these two approaches and highlights the fundamental principles that determine rates of food assimilation and rates of energy allocation to maintenance, biosynthesis, activity, and storage. The model predicts that growth and assimilation rates for all animals should cluster closely around two universal curves. Data for mammals and birds of diverse body sizes and taxa support these predictions.     

Human prion protein with valine 129 prevents expression of variant CJD phenotype

Variant Creutzfeldt-Jakob disease (vCJD) is a unique and highly distinctive clinicopathological and molecular phenotype of human prion disease associated with infection with bovine spongiform encephalopathy (BSE)-like prions. Here, we found that generation of this phenotype in transgenic mice required expression of human prion protein (PrP) with methionine 129. Expression of human PrP with valine 129 resulted in a distinct phenotype and, remarkably, persistence of a barrier to transmission of BSE-derived prions on subpassage. Polymorphic residue 129 of human PrP dictated propagation of distinct prion strains after BSE prion infection. Thus, primary and secondary human infection with BSE-derived prions may result in sporadic CJD-like or novel phenotypes in addition to vCJD, depending on the genotype of the prion source and the recipient.     

Cysteine redox sensor in PKGIa enables oxidant-induced activation

Changes in the concentration of oxidants in cells can regulate biochemical signaling mechanisms that control cell function. We have found that guanosine 3',5'-monophosphate (cGMP)-dependent protein kinase (PKG) functions directly as a redox sensor. The Ialpha isoform, PKGIalpha, formed an interprotein disulfide linking its two subunits in cells exposed to exogenous hydrogen peroxide. This oxidation directly activated the kinase in vitro, and in rat cells and tissues. The affinity of the kinase for substrates it phosphorylates was enhanced by disulfide formation. This oxidation-induced activation represents an alternate mechanism for regulation along with the classical activation involving nitric oxide and cGMP. This mechanism underlies cGMP-independent vasorelaxation in response to oxidants in the cardiovascular system and provides a molecular explantion for how hydrogen peroxide can operate as an endothelium-derived hyperpolarizing factor.     

Hematology of healthy Florida manatees (Trichechus manatus)

Background: Hematologic analysis is an important tool in evaluating the general health status of free‐ranging manatees and in the diagnosis and monitoring of rehabilitating animals. Objectives: The purpose of this study was to evaluate diagnostically important hematologic analytes in healthy manatees (Trichechus manatus) and to assess variations with respect to location (free ranging vs captive), age class (small calves, large calves, subadults, and adults), and gender. Methods: Blood was collected from 55 free‐ranging and 63 captive healthy manatees. Most analytes were measured using a CELL‐DYN 3500R; automated reticulocytes were measured with an ADVIA 120. Standard manual methods were used for differential leukocyte counts, reticulocyte and Heinz body counts, and plasma protein and fibrinogen concentrations. Results: Rouleaux, slight polychromasia, stomatocytosis, and low numbers of schistocytes and nucleated RBCs (NRBCs) were seen often in stained blood films. Manual reticulocyte counts were higher than automated reticulocyte counts. Heinz bodies were present in erythrocytes of most manatees. Compared with free‐ranging manatees, captive animals had slightly lower MCV, MCH, and eosinophil counts and slightly higher heterophil and NRBC counts, and fibrinogen concentration. Total leukocyte, heterophil, and monocyte counts tended to be lower in adults than in younger animals. Small calves tended to have higher reticulocyte counts and NRBC counts than older animals. Conclusions: Hematologic findings were generally similar between captive and free‐ranging manatees. Higher manual reticulocyte counts suggest the ADVIA detects only reticulocytes containing large amounts of RNA. Higher reticulocyte and NRBC counts in young calves probably reflect an increased rate of erythropoiesis compared with older animals.