Use of geophysical methods for the study of sandy soils under Campinarana at the National Park of Viruá, Roraima state,Brazilian Amazonia

Purpose

The vegetation of the Campinaranas occurs in humid areas with hydromorphic sandy soils at the Amazon region. Thus, the determination and in situ monitoring of moisture content in Campinarana soils, besides the detection of subsurface layers are key measures for studying these soil–vegetation systems. Also, the application of ground penetrating radar (GPR) in deep sandy sedimentary sequence of Amazonia is a promising tool to enhance the knowledge on depositional and soil formation features.

Materials and methods

We studied representative soils of the Campinaranas at the National Park of Viruá, state of Roraima (Brazilian Amazonia), through the use of geophysical methods (soil moisture sensors and GPR). The study was applied in four sandy soils. Besides chemical and physical analysis of soils, soil moisture sensors were installed for monitoring during an entire hydrological year (2010/2011), and performed the calibration of sensors , coupled with imaging of the soil along transects with GPR.

Results and discussion

As a result of calibration of the soil moisture sensors we obtained a general equation with an R ² greater than 0.9. There is an influence of soil moisture content and soil temperature in the distribution of vegetation types in Campinaranas. The use of GPR identified some determinants characteristics in these soils for the differentiating the Campinaranas, represented by spodic and C horizons.

Conclusions

The spodic horizons in soils under Forest Campinarana provided potential errors in the determination of soil moisture, requiring calibration data for the precise use of this device. The investigation of the soil through the GPR showed interesting results, which allowed continuous visualization of the main soil horizons along transects in the phytophysiognomies of Campinaranas.     

Dermal and serological response against Pseudomonas aeruginosa in sheep bred for resistance and susceptibility to fleece-rot

Genetically select lines of Merino sheep have been bred at Trangie (NSW Agriculture and Fisheries) for resistance (R) or susceptibility (S) to fleece-rot and flystrike. It is believed that fleece characters are primarily responsible for the R or S phenotype. When transferred to the wetter coastal environment of Sydney, R and S sheep with no more than 6 weeks wool cover, continued to show significant differences in the incidence and severity of fleece-rot dermatitis. To test the hypothesis that these sheep might also exhibit differences in their local skin reactions and immune responsiveness, 3 intradermal injections of killed Pseudomonas aeruginosa were administered at monthly intervals. After primary intradermal challenge, R sheep had a higher incidence of skin induration and a stronger inflammatory response (increased induration diameter) than S sheep. Compared to S sheep, R sheep also developed higher levels of circulating antibodies against whole cell antigen and both inner and outer membrane proteins of P. aeruginosa. These responses were maintained in R sheep with each consecutive challenge while S sheep showed a decline in their immune responsiveness. Differences in antibody response against outer membrane proteins were also detected when antigenically naive sheep from each genetic line were sensitised by epicutaneous challenge with P. aeruginosa under experimental wetting conditions. Intradermal challenge of these animals 6 months later with outer membrane proteins, revealed a late maximum (72 h) in the development of induration diameters for R sheep while S animals showed maximal induration diameters by 24 h. However, there was no significant difference in induration response between 24 h and 72 h within each group of sheep.(ABSTRACT TRUNCATED AT 250 WORDS)     

Crystal structure of the dynein motor domain

Dyneins are microtubule-based motor proteins that power ciliary beating, transport intracellular cargos, and help to construct the mitotic spindle. Evolved from ring-shaped hexameric AAA-family adenosine triphosphatases (ATPases), dynein's large size and complexity have posed challenges for understanding its structure and mechanism. Here, we present a 6 angstrom crystal structure of a functional dimer of two ~300-kilodalton motor domains of yeast cytoplasmic dynein. The structure reveals an unusual asymmetric arrangement of ATPase domains in the ring-shaped motor domain, the manner in which the mechanical element interacts with the ATPase ring, and an unexpected interaction between two coiled coils that create a base for the microtubule binding domain. The arrangement of these elements provides clues as to how adenosine triphosphate-driven conformational changes might be transmitted across the motor domain.     

Synthetic polypeptide antagonists of the hypothalamic luteinizing hormone releasing factor

Two analogs of the hypothalamic luteinizing hormone releasing factor modified at the histidine-2 position were tested for biological activity (secretion of luteinizing hormone) in cultures of dispersed rat anterior pituitary cells. The analog in which glycine was substituted for histidine at position 2, [Gly(2)]LRF, behaves as a partial agonist releasing less than 50 percent of the luteinizing hormone secreted at maximum concentrations of the releasing factor, while the analog in which histidine at position 2 is deleted has no significant agonist activity at any of the doses tested. When added to the cultured cells at molar ratios 10(3) to 10(4) times that of the luteinizing hormone releasing factor, both analogs decrease the amount of luteinizing hormone secreted in response to the releasing factor.     

Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films

Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.     

Bats,pangolins, minks and other animals - villains or victims of SARS-CoV-2?

Veterinary Research Communications - Coronavirus disease-19 (COVID-19) is caused by the severe acute Respiratory syndrome coronavirus-2 (SARS-CoV-2), which has become unstoppable, spreading rapidly...     

Resistance of barley genotypes to brown leaf spot

Resistance of 59 barley cultivars to three distinct isolates of Bipolaris sorokiniana, causing brown leaf spot was tested on seedlings and adult plants in a screen house and in a growth room, by determination of disease incidence, disease severity, and rate of lesion expansion. The disease reaction and severity at the seedling stage differed among cultivars. The cultivars MNS Brite, NDB 112, Kindred, Parkland, and Oderbrucke were moderately resistant to brown leaf spot, but the resistance was partial to all three isolates. None genotype with complete resistance was found. The cultivars CI 9539, Svanhals, and Chevron, considered as sources of resistance, were classified as moderately susceptible, and susceptible, respectively. Disease severity, disease reaction, and incidence of B. sorokiniana in grains also differed among the cultivars at the adult plant stage. Nevertheless, none of the genotypes was resistant to B. sorokiniana. The rate of lesion expansion differed among cultivars BR 2, MN 698, Kitchin, Svanhals, and NDB 112, with NDB 112 having the slowest expansion rate (0.194–0.205 mm²/day).     

Physiologic effects of furosemide in combination with water restriction when administered at 4 and 24 hours prior to high-intensity treadmill training

Although controversial, due to its reported effectiveness in attenuating bleeding associated with exercise-induced pulmonary hemorrhage (EIPH), furosemide is currently a permitted race day medication in most North American racing jurisdictions. The objective of this study was to assess the efficacy of furosemide in reducing the presence and severity of EIPH when administered 24 hr prior to strenuous treadmill exercise. Eight exercised Thoroughbred horses received saline or 250 mg of furosemide either 4 or 24 hr prior to high-speed treadmill exercise in a balanced 3-way cross-over design. Blood samples were collected for determination of furosemide, lactate, hemoglobin, blood gas, and electrolyte concentrations. Heart rate and pulmonary arterial pressure were measured throughout the run and endoscopic examination and bronchoalveolar lavage (BAL) performed. Horses were assigned an EIPH score and the number of red blood cells in BAL fluid determined. Although not significantly different, endoscopic EIPH scores were lower in the 4-hr versus the 24-hr and saline groups. RBC counts were not significantly different between the treatment groups. Pulmonary arterial pressures were significantly increased at higher speeds; however, there were no significant differences between dose groups when controlling for speed. A small sample size and unknown bleeding history warrant a larger-scale study.