Negative Poisson's ratios for extreme states of matter

Negative Poisson's ratios are predicted for body-centered-cubic phases that likely exist in white dwarf cores and neutron star outer crusts, as well as those found for vacuumlike ion crystals, plasma dust crystals, and colloidal crystals (including certain virus crystals). The existence of this counterintuitive property, which means that a material laterally expands when stretched, is experimentally demonstrated for very low density crystals of trapped ions. At very high densities, the large predicted negative and positive Poisson's ratios might be important for understanding the asteroseismology of neutron stars and white dwarfs and the effect of stellar stresses on nuclear reaction rates. Giant Poisson's ratios are both predicted and observed for highly strained coulombic photonic crystals, suggesting possible applications of large, tunable Poisson's ratios for photonic crystal devices.     

The shared antibiotic resistome of soil bacteria and human pathogens

Soil microbiota represent one of the ancient evolutionary origins of antibiotic resistance and have been proposed as a reservoir of resistance genes available for exchange with clinical pathogens. Using a high-throughput functional metagenomic approach in conjunction with a pipeline for the de novo assembly of short-read sequence data from functional selections (termed PARFuMS), we provide evidence for recent exchange of antibiotic resistance genes between environmental bacteria and clinical pathogens. We describe multidrug-resistant soil bacteria containing resistance cassettes against five classes of antibiotics (β-lactams, aminoglycosides, amphenicols, sulfonamides, and tetracyclines) that have perfect nucleotide identity to genes from diverse human pathogens. This identity encompasses noncoding regions as well as multiple mobilization sequences, offering not only evidence of lateral exchange but also a mechanism by which antibiotic resistance disseminates.     

Identification of parasites in Puffinus puffinus (Birds, Procellariiformes) from Northeastern Brazil

Studies on the parasitic fauna of migratory sea birds of the Puffinus genus are scarce. Therefore, the aim of this study was to identify parasites of 16 specimens of Puffinus puffinus (Procellariiformes, Procellariidae) that died during the period of June 2011 to December 2011 at the Wildlife Screening Center (CETAS) of the Brazilian Institute of Environment and Natural Resources (IBAMA) in Cabedelo, Paraíba. During necropsy, biting lice and/or gastrointestinal helminths were collected in seven (43.7?%) birds. Lice were collected in five (31.2?%) birds, and the species identified were Halipeurus diversus, Trabeculus aviator, Austromenopon paululum), Saemundssonia sp. and Naubates sp. The prevalence of helminths was also 31.2?%. The nematodes species were Seuratia shipleyi and Contracaecum sp., and cestodes were Tetrabothrius sp. This is the first record in Brazil of Naubates sp., Seuratia shipleyi, Contracaecum sp., and Tetrabothrius sp. in Puffinus puffinus.     

Partial replacement of fishmeal with biofloc meal in the diet of postlarvae of the Pacific white shrimp Litopenaeus vannamei

This study evaluated the potential for the replacement of fishmeal (FM) by biofloc meal (BM) in the diet of Litopenaeus vannamei postlarvae. Four isonitrogenous (437.42 g kg^?1) and isocaloric (19.84 kJ g^?1) diets were formulated, in which FM was replaced with BM at 0% (T0), 7.5% (T7.5), 15% (T15) and 30% (T30). A commercial diet (CD) was used as reference. The study was conducted over 42 days in 50 L tanks connected to a water recirculation system. All tanks were stocked with three postlarvae (initial weight 0.0023 g) per litre. Shrimp survival, weight gain (WG), final weight (FW), specific growth rate (SGR) and protein efficiency ratio (PER) were measured. Survival rates were high (>91.1%) in all treatments. As the T30 treatment returned a significantly (<0.05) better performance in WG, FW, SGR and PER than all other treatments, partial replacement of FM with BM does not appear to affect productivity. In fact, a regression analysis indicated that a FM to BM replacement level of over 20% may actually improve shrimp growth. In addition to providing a cost‐effective alternative ingredient for L. vannamei postlarvae diets, the production of meal also represents a more sustainable way of disposing of the excess of biofloc produced by BFT systems.     

Polymorphic microsatellite marker set for <Emphasis Type="Italic">Carica papaya</Emphasis> L. and its use in molecular-assisted selection

Conventional methods for the selection of papaya pure lines are time-consuming. Procedures involving the use of molecular markers and the indirect selection of homozygous plants can reduce this time considerably. The objective of this study was to evaluate the informativeness of a microsatellite marker set when used in marker-assisted selection (MAS) for the development of new papaya lines. Eighty-three lines originating from two segregating F₃ populations and from papaya germplasm were used for the molecular analysis of 27 microsatellite primers. Twenty polymorphic microsatellite primers were identified, allowing the identification of 86 alleles, with an average of 3.18 alleles per primer. The observed heterozygosity values were low for both the markers (0.00–0.29) and the individual lines (0.00–0.35). The inbreeding coefficient (f) ranged from 0.634 to 1.00. Eleven lines with f = 1.00 and 18 lines with f varying from 0.953 to 0.961 were identified. In addition, papaya lines showed high genetic diversity, which will certainly contribute to the development of new varieties. Our results show that the use of microsatellites in MAS is a quick and effective procedure for the development of papaya lines.     

Modulation of cutaneous inflammation induced by ticks in contrasting phenotypes of infestation in bovines

Tick saliva contains molecules that are inoculated at the site of attachment on their hosts in order to modulate local immune responses and facilitate a successful blood meal. Bovines express heritable, contrasting phenotypes of infestations with the cattle tick, Rhipicephalus (Boophilus) microplus: breeds of Bos taurus indicus are significantly more resistant than those of Bos taurus taurus. Tick saliva may contain molecules that interfere with adhesion of leukocytes to endothelium and resistant hosts may mount an inflammatory profile that is more efficient to hamper the tick's blood meal. We show in vitro that adhesion of peripheral blood mononuclear cells to monolayers of cytokine-activated bovine umbilical endothelial cells was significantly inhibited by tick saliva. The inflammatory response to bites of adults of R. microplus mounted by genetically resistant and susceptible bovine hosts managed in the same pasture was investigated in vivo. The inflammatory infiltrates and levels of message coding for adhesion molecules were measured in biopsies of tick-bitten and control skin taken when animals of both breeds were exposed to low and high tick infestations. Histological studies reveal that cutaneous reactions of resistant hosts to bites of adult ticks contained significantly more basophils and eosinophils compared with reactions of the susceptible breed. Expression of the adhesion molecules – intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and P-selectin – was higher in adult-infested skin of susceptible hosts undergoing low infestations compared to resistant hosts; when host was exposed to high infestations expression of these adhesion molecules was down-regulated in both phenotypes of infestations. Expression of leukocyte adhesion glycoprotein-1 (LFA-1) was higher in skin from susceptible hosts undergoing low or high infestations compared to resistant hosts. Conversely, higher levels of E-selectin, which promotes adhesion of memory T cells, were expressed in skin of resistant animals. This finding may explain the resistant host's ability to mount more rapid and efficient secondary responses that limit hematophagy and infestations. The expression profiles observed for adhesion molecules indicate that there are differences in the kinetics of the inflammatory reactions mounted by resistant and susceptible hosts and the balance between tick and host is affected by the number of tick bites a host receives. We show that the contrasting phenotypes of infestations seen in bovines infested with R. microplus are correlated with differences in the cellular and molecular composition of inflammatory infiltrates elicited by bites with adult ticks.     

Nitrogen dynamics in soil solution under different land uses: Atlantic forest and cacao–cabruca system

In the southern region of Bahia, a large portion of the Atlantic Forest was occupied by the cacao–cabruca system, which is implemented after the complete removal of the understory vegetation without altering the canopy. The objective of this study was to determine the nitrogen concentration in the soil solution in two micro-basins; one with the cacao–cabruca system and one in the Atlantic forest in the southern region of the state of Bahia. Samples were collected weekly during two periods, from September to December 2012 and from April to June 2013, using sample extractors installed in the micro-basins at 15, 45 and 90 cm. The inorganic forms in the soil solutions were analyzed through ion chromatography, total nitrogen was analyzed using spectrophotometry and mineralization and nitrification rates were analyzed using the laboratory incubation method. Among the nitrogen forms analyzed in the cacao–cabruca soil solution, the dissolved organic nitrogen prevailed among the rain classes in the three depths. In the forest, nitrate predominated at 15 cm, while the organic nitrogen prevailed in the other depths. The highest mineralization and nitrification rates were recorded in the forest. Of the inorganic nitrogen forms analyzed in the soil, ammonium concentrations showed higher rates than nitrate in both areas. Low inorganic nitrogen concentrations in the cabruca soil solution are associated with low mineralization and nitrification rates. Thus we can conclude that even if some studies point towards the environmental efficiency of this system, there are differences in the N forms in the forest and cacao–cabruca areas.     

Fresh and stored copra meal in meat quail diets

Tropical Animal Health and Production - The aim of the current study was to evaluate the addition of fresh and stored copra meal to the diet of meat quails. Two hundred eighty-seven-day-old male...