The geologically recent giant impact basins at Vesta's south pole

Dawn's global mapping of Vesta reveals that its observed south polar depression is composed of two overlapping giant impact features. These large basins provide exceptional windows into impact processes at planetary scales. The youngest, Rheasilvia, is 500 kilometers wide and 19 kilometers deep and finds its nearest morphologic analog among large basins on low-gravity icy satellites. Extensive ejecta deposits occur, but impact melt volume is low, exposing an unusual spiral fracture pattern that is likely related to faulting during uplift and convergence of the basin floor. Rheasilvia obliterated half of another 400-kilometer-wide impact basin, Veneneia. Both basins are unexpectedly young, roughly 1 to 2 billion years, and their formation substantially reset Vestan geology and excavated sufficient volumes of older compositionally heterogeneous crustal material to have created the Vestoids and howardite-eucrite-diogenite meteorites.     

The structures of COPI-coated vesicles reveal alternate coatomer conformations and interactions

Transport between compartments of eukaryotic cells is mediated by coated vesicles. The archetypal protein coats COPI, COPII, and clathrin are conserved from yeast to human. Structural studies of COPII and clathrin coats assembled in vitro without membranes suggest that coat components assemble regular cages with the same set of interactions between components. Detailed three-dimensional structures of coated membrane vesicles have not been obtained. Here, we solved the structures of individual COPI-coated membrane vesicles by cryoelectron tomography and subtomogram averaging of in vitro reconstituted budding reactions. The coat protein complex, coatomer, was observed to adopt alternative conformations to change the number of other coatomers with which it interacts and to form vesicles with variable sizes and shapes. This represents a fundamentally different basis for vesicle coat assembly.     

农副产品及废弃物化感抑藻作用的研究与机理

农副产品废弃物作为可再生性、可降解性的生物质资源,在农村被大量的丢弃和焚烧,给环境造成了极大地危害.通过一系列技术处理,可以从农副产品和废弃物中提取化感物质,应用于海水和淡水中藻类的抑制,以有效利用废物资源.文章对化感作用的概念、20种农副产品及废弃物对19种藻类的化感抑制作用以及化感作用抑藻机理等进行了较系统的论述,对今后植物化感作用抑藻技术的研究方向进行了展望.提出应多学科结合,利用化感物质对不同藻类的影响及其选择性抑制机理做更深入的研究.     

Diversity of genome segment B from infectious bursal disease viruses in the United States

Several phylogenetic lineages of the infectious bursal disease virus (IBDV) genome segment B have been identified. Although this genome segment has been shown to contribute to virulence, little is known about the genetic lineages that exist in the United States. The nucleotide genome segment B sequences of 67 IBDV strains collected from 2002 to 2011 in the United States were examined. Although they were from nine different states, a majority (47) of these viruses were from California. A 722-base pair region near the 5' end of genome segment B, starting at nucleotide 168 and ending at 889, was examined and compared to sequences available in GenBank. The nucleotide sequence alignment revealed that mutations were frequently observed and that they were uniformly spaced throughout the region. When the predicted amino acids were aligned, amino acids at positions 145, 146, and 147 were found to change frequently. Six different amino acid triplets were observed and the very virulent (vv) IBDV strains (based on presence of vvIBDV genome segment A sequence) all had the triplet T145, D146, and N147. None of the non-vvIBDV strains had this TDN triplet. Phylogenetic analysis of the 67 nucleotide sequences revealed four significant genome segment B lineages among the U.S. viruses. One of these included the genome segment B typically found in vvIBDV and three contained non-vvIBDV genome segment B sequences. When the available sequences in GenBank were added to the analysis, two additional lineages were observed that did not contain U.S. viruses; one included viruses from China and the other contained viruses from the Ivory Coast. Although the samples tested do not represent all poultry producing regions in the United States, serotype 1 viruses from states outside California all belonged to one genome segment B lineage. The other three lineages observed in the United States were populated with viruses exclusively found in California, except the serotype 2 lineage, where the type strain was a serotype 2 virus from Ohio. The data provide further evidence for the importance of genome segment B identification during routine molecular diagnosis of all IBDV strains.     

Influence of different supplements and sugarcane (Saccharum officinarum L.) cultivars on intake, digestible variables and methane production of dairy heifers under tropical conditions

The sulphur hexafluoride (SF(6)) gas tracer method was used to measure methane (CH(4)) production of crossbred (3/4 Holstein x Zebu) dairy heifers fed two types of sugarcane (Saccharum officinarum L.; cultivar IAC-862480 (CC1) or cultivar IAC-873184 (CC2)) and supplemented with urea or concentrate. The study was performed at Embrapa Southeast Cattle, S?o Carlos, SP, Brazil, using a completely randomised design. Differences between treatments were significant for digestibility of dry matter, organic matter and energy. When animals were supplemented with urea differences between sugarcane cultivars did occur for NDF consumption, but not for daily methane production. This suggest that variation in chemical composition of sugarcane did not affect bovine ruminal CH(4) emissions. Concentrate inclusion in animal diet increased digestible organic matter intake, improving the nutrient intake by animals, but did not reduce CH(4) production expressed as a percentage of gross energy intake.     

Upfront denileukin diftitox as in vivo regulatory T-cell depletion in order to enhance vaccination effects in a canine allogeneic hematopoietic stem cell transplantation model

Denileukin Diftitox (ONTAK^®, DAB₃₈₉ IL-2) is a recombinant DNA-derived fusion protein depleting cells that express high-affinity IL-2 receptor. Important cell targets are CD4⁺CD25⁺Foxp3⁺ regulatory T cells (T_reg). Elimination of immunosuppressive T_reg by Denileukin Diftitox may provide a way to modulate immune tolerance following stem cell transplantation. Here, we combined T_reg depletion with a vaccination approach to induce donor-specific immune reactions. To investigate this approach we chose the mixed chimerism canine stem cell transplantation model which represents a high state of tolerance between two hematopoietic systems. The aim was therefore to induce a graft versus hematopoiesis effect thereby converting mixed to full donor chimerism. Dog leukocyte antigen identical siblings that had developed a stable mixed chimerism after non-myeloablative stem cell transplantation received a single dose of Denileukin Diftitox (18 μg/kg, i.v.) followed by several cell-lysate vaccinations. Host peripheral blood mononuclear cell lysates combined with CpG-ODN, and Montanide^® ISA 51 were locally applied. In vitro studies demonstrated that canine T_reg are a target of Denileukin Diftitox. The suppression of T-cell proliferation by T_reg was abolished by addition of Denileukin Diftitox (10 nM). An increase of proliferation of median 300% (range: 200%–425%) was observed. No change in donor chimerism was observed after administration of Denileukin Diftitox and vaccination. This study highlights that application of Denileukin Diftitox resulted in a depletion of T_reg followed by an increase of immune response in vitro. This effect could not be confirmed in vivo even if the immune system was stimulated by vaccinations.     

Patch testing and allergen-specific serum IgE and IgG antibodies in the diagnosis of canine adverse food reactions

Adverse food reaction (AFR) is a common differential diagnosis for pruritic dogs. The only way to diagnose AFR is an elimination diet of 6-8 weeks with a protein and a carbohydrate source not previously fed. In humans, patch testing has been shown to be a useful tool to diagnose food allergies. In veterinary medicine, serum food allergen-specific antibody testing is widely offered to identify suitable ingredients for such diets. The aim of this study was to determine sensitivity, specificity, negative and positive predictability of patch testing with and serum antibody testing for a variety of common food stuffs. Twenty-five allergic dogs underwent an elimination diet and individual rechallenge with selected food stuffs, food patch testing and serum testing for food-antigen specific IgE and IgG. Eleven clinically normal control dogs only were subjected to patch and serum testing. The sensitivity and specificity of the patch test were 96.7 and 89.0% respectively, negative and positive predictability were 99.3 and 63.0%. For IgE and IgG the sensitivity was 6.7 and 26.7%, specificity were 91.4 and 88.3%, the negative predictive values 80.7 and 83.7% and the positive predictive values were 15.4 and 34.8%. Based on these results, a positive reaction of a dog on these tests is not very helpful, but a negative result indicates that this antigen is tolerated well. We conclude that patch testing (and to a lesser degree serum testing) can be helpful in choosing ingredients for an elimination diet in a dog with suspected AFR.     

Effect of oil-based formulations of acaripathogenic fungi to control Rhipicephalus microplus ticks under laboratory conditions

The formulations of acaripathogenic fungi to control ticks have been widely studied. The present study evaluated the efficacy of oil-based formulations of Metarhizium anisopliae sensu lato (s.l.), isolate Ma 959, and Beauveria bassiana, isolate Bb 986, on different Rhipicephalus microplus stages, comparing the efficacy between aqueous suspensions and 10, 15 and 20% mineral oil formulations. Twelve groups were formed: one aqueous control group; three mineral oil control groups, at 10, 15 or 20%; two aqueous fungal suspensions of M. anisopliae s.l. or B. bassiana; and three formulations of M. anisopliae (s.l.) or B. bassiana containing 10, 15, and 20% mineral oil. To prepare aqueous suspensions and oily formulations, fungal isolates were cultivated on rice grains in polypropylene bags. The conidial suspensions and formulations had a concentration of 10(8)conidia/mL. Bioassays were repeated twice. After treatment, the following biological parameters of engorged females were evaluated: hatching percentage, egg production index, nutritional index, and percentage of tick control. The following parameters were evaluated in the bioassays with eggs: period of incubation, period of hatch, and hatching percentage. Mortality was evaluated in bioassays with larvae. M. anisopliae s.l. and B. bassiana oil-based formulations were more effective than aqueous suspensions against R. microplus eggs, larvae and engorged females, however, there was no significant difference between the three oil concentrations used. M. anisopliae s.l. and B. bassiana formulated in mineral oil reached 93.69% and 21.67% efficacy, respectively, while M. anisopliae s.l. and B. bassiana aqueous suspensions attained 18.70% and 1.72% efficacy, respectively. M. anisopliae s.l. oil-based formulations caused significant effects in all biological parameters of engorged females while B. bassiana oil-based formulations modified significantly the nutritional index only. Eggs treated with M. anisopliae s.l. and B. bassiana oil-based formulations showed hatching rates that decreased 102.5 and 3.65 times, respectively. In the bioassay with larvae, M. anisopliae s.l. oil-based formulations caused nearly 100% mortality five days after treatment, while larva treated with B. bassiana oil-based formulations reached 100% mortality at day 20 after treatment. Larva from oil-based control groups showed mortality at day 15 after treatment, which indicated a possible toxic effect of the oil for this R. microplus stage. The results showed that the fungal mineral oil formulations tested were more effective than the aqueous suspension. Oil-based formulations at 10, 15 and 20% enhanced the activity of M. anisopliae s.l. Ma 959, and B. bassiana Bb 986, isolates against R. microplus eggs, larvae, and engorged females tick. Mineral oil was effective as an adjuvant in formulations of M. anisopliae s.l., Ma 959, and B. bassiana, Bb 986, for the control of R. microplus under laboratory conditions.     

More than classical Chlamydia psittaci in urban pigeons

In the literature, studies of Chlamydia infection in birds have usually been confined to the search for Chlamydia (C., formerly Chlamydophila) psittaci, so that little is known about the presence of other chlamydial agents. In the present study, cloacal swabs and faeces samples of urban pigeons have been examined by real-time PCR, DNA microarray assays and partial ompA sequencing. Whilst C. psittaci was the predominant chlamydial agent in this pigeon population (75.8% of all Chlamydiaceae positives), the combined use of highly specific and sensitive molecular assays facilitated the detection of atypical serovars of C. psittaci, as well as other species of Chlamydia, such as C. abortus. Detection of C. pecorum and C. trachomatis from an avian host is reported here for the first time. Rather unexpectedly, 19.5% of all Chlamydiaceae-positive cases turned out to be infected with non-classified organisms. The considerable prevalence of these novel agents raises the question of their epidemiological importance and possible role as pathogens. Future surveys in domestic and wild birds will have to take the extended variety of chlamydial organisms into account.