New horizons mapping of Europa and Ganymede

The New Horizons spacecraft observed Jupiter's icy satellites Europa and Ganymede during its flyby in February and March 2007 at visible and infrared wavelengths. Infrared spectral images map H2O ice absorption and hydrated contaminants, bolstering the case for an exogenous source of Europa's "non-ice" surface material and filling large gaps in compositional maps of Ganymede's Jupiter-facing hemisphere. Visual wavelength images of Europa extend knowledge of its global pattern of arcuate troughs and show that its surface scatters light more isotropically than other icy satellites.     

Radiohalos in coalified wood: new evidence relating to the time of uranium introduction and coalification

The discovery of embryonic halos around uranium-rich sites that exhibit very high (238)U/(206)Pb ratios suggests that uranium introduction may have occurred far more recently than previously supposed. The discovery of (210)Po halos derived from uranium daughters, some elliptical in shape, further suggests that uranium-daughter infiltration occurred prior to coalification when the radionuclide transport rate was relatively high and the matrix still plastically deformable.     

Primary Production in Antarctic Sea Ice

A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 teragrams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea.     

European cretaceous flints on the coast of north america

Flint pebbles and nodules from the Upper Cretaceous chalks of Europe occur offshore and at many seaports along the Atlantic coast of North America, where they were brought as ship's ballast. Isolated pieces imported from Europe as gunflints also are present.     

The mentality of crows: convergent evolution of intelligence in corvids and apes

Discussions of the evolution of intelligence have focused on monkeys and apes because of their close evolutionary relationship to humans. Other large-brained social animals, such as corvids, also understand their physical and social worlds. Here we review recent studies of tool manufacture, mental time travel, and social cognition in corvids, and suggest that complex cognition depends on a "tool kit" consisting of causal reasoning, flexibility, imagination, and prospection. Because corvids and apes share these cognitive tools, we argue that complex cognitive abilities evolved multiple times in distantly related species with vastly different brain structures in order to solve similar socioecological problems.     

Induction of immunity against infection with Theileria parva (East Coast fever) in cattle using plasma membranes from parasitized lymphoblasts

Protection against challenge with Theileria parva was conferred on three of four calves given three or four inocula of plasma membranes prepared from 6 to 12 X 10(8) autologous parasitized lymphoblasts from cultured cell lines. In contrast, calves remained susceptible to infection following immunization with membranes prepared from allogeneic parasitized lymphoblasts. Similarly, calves vaccinated with either gamma-irradiated autologous or allogeneic infected cells also died of East Coast fever after challenge. The results raise the possibility of vaccination against T. parva using subcellular material from infected lymphoblasts.     

An analysis of cellular proliferation, and synthesis of lymphokines and specific antibody in vitro by leucocytes from immunized cattle

The relationships between the production of lymphokines, cellular proliferation and antibody synthesis by immune bovine PBL in vitro was examined to identify the cellular reactions responsible for differences in the titres of serum antibodies in calves from selected sire lines and MHC Class I phenotypes. Leucocytes from 22 calves immunized with ovalbumin and DNP-BSA proliferated specifically in vitro in the presence of 1-10 micrograms/ml ovalbumin 7-28 days after the second vaccination. Significant correlations between the production of IL-2, IFN-gamma and maximum proliferation were observed for the total group. The quantity of specific antibody produced when PBL were incubated alone or with 10(-1)-10(-2) micrograms/ml ovalbumin was also correlated significantly with the maximum proliferation and the serum antibody titre between 7 and 14 days. Anti-ovalbumin IgG was also synthesized in MLRs where the quantity of antibody was significantly correlated with the magnitude of proliferation. The responses in vitro to DNP-BSA were too low to provide meaningful comparisons. The results indicate that at intervals during the period of increasing serum titres, events in the bovine antibody response in vivo can be replicated in vitro. In addition, assays for proliferation, IL-2 or gamma-IFN, or specific antibody can be used to assess the magnitude of the immune response in vivo in experimental groups of cattle. Significant sire line differences in the serological responses to ovalbumin were observed but DNP-BSA was a poorer antigen and differences in the responses to this antigen were not significant. However, the sire line differences in vivo were not reflected in vitro in proliferative and lymphokine assays; only the production of antibody in vitro was significantly correlated with the in vivo serum titre.     

A functional and biochemical analysis of bovine class II MHC antigens using monoclonal antibodies

Monoclonal antibodies (MAbs) reacting with bovine (2) ovine (3), murine (1) or human (1) Class II MHC antigens were examined for reactivity with bovine peripheral blood leucocytes (PBL) and lymph node cells (LNC) by immunofluorescence, immunoprecipitation and the capacity to inhibit mixed lymphocyte responses (MLR), lectin- and antigen-induced blastogenesis. The 6 MAbs identified comparable percentages of Class II positive lymphocytes in PBL (40.8 to 54.2%) and LNC (6 to 11.5%) regardless of BoLA-A phenotype. Immunohistological staining of Class II MAb was localized principally to the lymphoid follicles in lymph nodes and to isolated epithelial reticular cells in the thymus. The anti-Class II MAb immunoprecipitated alpha- and beta- chains of 26-29K and 32-34K, respectively. These MAb inhibited proliferative responses in the MLR by between 25 and 74%, and diminished blastogenesis induced by specific antigens (purified protein derivative + PPD and ovalbumin) and B-lymphocyte mitogens (PPD, lipopolysaccharide and dextran sulphate) by between 45 and 75%, regardless of BoLA-A phenotype. In contrast, proliferation in response to concanavalin A and phytohaemagglutinin were unaffected by the anti- Class II MAb. Similarly these MAb did not affect lysis by cytotoxic T-lymphocytes, the activity of which was depressed by anti-Class I MAbs and monospecific alloantisera.     

Relationship of hepatic lipidosis to health and performance in dairy cattle

In a field study of 80 cows in 9 dairy herds, serial liver biopsies were performed over the peripartum period to determine degree of hepatic lipidosis. Cattle were separated into categories of mild, moderate, and severe hepatic lipidosis on the basis of maximal amounts of hepatic triglyceride that accumulated during this period. Number of cattle with mild, moderate, and severe hepatic lipidosis were 52, 16, and 12, respectively. Cattle with severe hepatic lipidosis had greater concentrations of hepatic triglyceride before calving and after parturition, and greater serum nonesterified fatty acid concentrations and body condition loss after parturition than cattle with mild hepatic lipidosis. Rate of disease and culling and death rate because of disease were greater in cattle with severe hepatic lipidosis. Cattle with severe hepatic lipidosis had reproductive performance equal to clinically normal cattle; however, cattle with moderate hepatic lipidosis had increased days to conception, possibly related to greater milk production.     

Significance for exercise capacity of some electrocardiographic findings in racehorses

Summary Various cardiorespiratory and metabolic indices were assessed during treadmill exercise in Thoroughbred and Standardbred racehorses with T wave changes in 4 or more leads on the electrocardiogram or second-degree atrio-ventricular (AV) block, and in horses that had no abnormalities on clinical examination, resting electrocardiography or upper respiratory tract endoscopy. No significant differences in heart rate, plasma lactate concentration, arterial blood gases, oxygen uptake, run time, peak velocity, or blood and red cell volumes were found between normal horses and horses with T wave changes or second-degree AV block. These results indicate that some electrocardiographic findings that are considered by some clinicians to indicate cardiac dysfunction, may have little effect on exercise capacity.