Assessing conservation priorities of endemic freshwater fishes in the Tropical Andes region     

Marcelo F. Tognelli  Elizabeth P. Anderson  Luz F. Jimnez‐Segura  Junior Chuctaya  Luisa Chocano  Javier A. Maldonado‐Ocampo  Lina Mesa‐Salazar  Jos I. Mojica  Fernando M. Carvajal‐Vallejos  Vanessa Correa  Hernn Ortega  Juan F. Rivadeneira Romero  Paula Snchez‐Duarte  Neil A. Cox  Max Hidalgo  Pedro Jimnez Prado  Carlos A. Lasso  Jaime Sarmiento  Miguel A. Velsquez  Francisco A. Villa‐Navarro 《水产资源保护:海洋与淡水生态系统》2019,29(7):1123-1132

Spatial hierarchical variances and age covariances for seroprevalence to Leptospira interrogans serovar hardjo, BoHV-1 and BVDV for cattle in the State of Paraíba, Brazil     

Thompson JA  de Miranda Henriques Leite R  Gonçalves VS  Leite RC  Bandeira DA  Herrmann GP  Moreira EC  Prado PE  Lobato ZI  de Brito CP  Lage AP 《Preventive veterinary medicine》2006,76(3-4):290-301

We estimated spatial hierarchal variances and age-group covariances for seroprevalence to Leptospira interrogans serovar hardjo (LeptoH), bovine viral-diarrhea virus (BVDV) and bovine herpesvirus type 1 (BoHV-1) among 2343 cattle from 72 properties sampled in the State of Paraíba, Brazil in 2000. From each property, eight animals in each of the four age categories were evaluated. The age categories studied were: pre-weaned (0–6 months), young (7–18 months), replacement (19–30 months) and mature (>30 months). Overall seroprevalence to LeptoH was 16.0% and showed clustering at all levels of the spatial hierarchy and had a high posterior probability of being negatively correlated between replacement and mature groups within herds. Seroprevalence to BoHV-1 was 46.6% and demonstrated very little clustering among levels of the spatial hierarchy and was positively correlated between young and replacement groups within herds. Seroprevalence to BVD was 22.2% and was strongly clustered within herds and was positively correlated between young and replacement age groups within herds.  相似文献   

Maternally and naturally acquired antibodies to Mannheimia haemolytica and Pasteurella multocida in beef calves     

Prado ME  Prado TM  Payton M  Confer AW 《Veterinary immunology and immunopathology》2006,111(3-4):301-307

The dynamics and duration of maternally derived antibodies as well as the onset of acquired immunity against Mannheimia haemolytica and Pasteurella multocida in range-pastured beef calves were investigated. Two groups of unvaccinated cattle were used in this study. Serum antibody responses were measured by enzyme-linked immunoassay for antibodies of the IgG1, IgG2 and IgM isotypes binding M. haemolytica whole cells (WC) or leukotoxin (LKT) and P. multocida outer membrane proteins (OMPs). Comparisons of mean antibody responses to M. haemolytica LKT and WC and P. multocida OMPs were made within each group. Maternally derived antibodies against M. haemolytica and P. multocida reached lowest levels at 30-90 days after birth. Calves began production of antibodies against M. haemolytica and P. multocida between 60 and 90 days of age in both groups. Based on the results of this study, in beef herds vaccinated against M. haemolytica and/or P. multocida, it may be best to vaccinate calves around 3 months of age. In contrast, beef calves from unvaccinated herds might benefit from vaccination at 4 months of age.  相似文献   

Structural collapse prevents beta-carotene loss in a supercooled polymeric matrix     

Prado SM  Buera MP  Elizalde BE 《Journal of agricultural and food chemistry》2006,54(1):79-85

The kinetics of degradation and surface color changes of beta-carotene encapsulated in a polymeric matrix (PVP-40) and its relationship with physical changes (manifested as structural collapse) of the matrix were studied during storage of samples at several water activities at constant temperature. The degradation rate constants obtained decreased with an increase in the relative humidity (RH) of the storage atmosphere. Beta-carotene losses were observed mainly at RHs below the glass transition temperature (Tg) of the corresponding systems, and the lower degradation constant rates were observed under conditions where the matrices were fully plasticized (i.e., rubbery) and collapsed (RH, 64 and 75%). An inverse correlation was observed between collapse and degradation rate constants. The results presented here indicated that the molecular mobility of the matrix is not rate limiting for the degradation of beta-carotene. Factors such as microstructure and porosity of the polymeric matrix may be more important as modifiers of kinetic reactions. Surface color was not a sensitive indicator of beta-carotene retention, because it was mostly affected by the degree of matrix hydration and collapse phenomena.  相似文献   

Kernel δ18O reflects changes in apical dominance and plant transpiration in tropical maize          下载免费PDF全文

L. Cabrera‐Bosquet  C. Grieder  S. Alvarez Prado  C. Sánchez  J. L. Araus 《Journal of Agronomy and Crop Science》2017,203(4):277-285

Modification of source–sink ratios in tropical maize through detasseling is an ancestral agronomical practice used for increasing yields under stressful conditions. However, the mechanisms behind such effect are not well understood given the difficulties to determine physiological processes such as photosynthesis and whole‐plant transpiration in the field. We have tested the potential ability of kernel δ ¹⁸O to assess differences in grain yield (GY ) through changes in plant transpiration caused by the modification of water availability and source–sink modification treatments, (including removal of the tassel and different numbers of leaves) in three tropical maize hybrids differing in drought tolerance. Drought‐tolerant genotypes displayed higher yields and lower kernel δ ¹⁸O values than the drought‐susceptible genotype under both well‐watered (WW ) and water‐stressed (WS ) conditions. Detasseling caused a positive increase in GY under well‐watered (up to 8%) and water‐deficit conditions (up to 36%). Reduction in leaf area (source) through defoliation treatments caused a large impact on GY showing a trade‐off between maintaining a photosynthetic versus transpiring leaf area. Thus, while a reasonable reduction in leaf area significantly improved plant water availability (as shown by lower kernel δ ¹⁸O values) and consequently GY under water deficit (up to 40%), it caused a maximum reduction of 25% in GY under well‐watered conditions. Variations in GY were significantly (p  <  .05) correlated with changes in δ ¹⁸O under both well‐watered (r  =  ?.67) and WS conditions (r  =  .75 and .82). Our results also reinforce the utility of δ ¹⁸O measured in mature kernels as a powerful ecophysiological tool for assessing genotypic differences in apical dominance, transpiration and yield under both WW and WS conditions in tropical maize.  相似文献   

Vinasse Dynamics on Soil Solution Under Sugarcane Crop: Inorganic and Organic Ion Analysis     

Eber Augusto Ferreira Do Prado  Antonio Carlos Tadeu Vitorino  Giuliano Marchi  Daphne Heloisa de Freitas Muniz  Tomaz Alvez de Souza 《Water, air, and soil pollution》2016,227(5):145

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Lolium rigidum, a pool of resistance mechanisms to ACCase inhibitor herbicides     

De Prado JL  Osuna MD  Heredia A  De Prado R 《Journal of agricultural and food chemistry》2005,53(6):2185-2191

Three diclofop-methyl (DM) resistant biotypes of Lolium rigidum (R1, R2, and R3) were found in different winter wheat fields in Spain, continuously treated with DM, DM + chlortoluron, or DM + isoproturon. Herbicide rates that inhibited shoot growth by 50% (ED50) were determined for DM. There were found that the different biotypes exhibited different ranges of resistance to this herbicide; the resistant factors were 7.2, 13, and 36.6, respectively. DM absorption, metabolism, and effects on ACCase isoforms were examined in these biotypes of L. rigidum. The most highly resistant, biotype R3, contained an altered isoform of ACCase. In biotype R2, which exhibited a medium level of resistance, there was an increased rate of oxidation of the aryl ring of diclofop, a reaction most likely catalyzed by a cytochrome P450 enzyme. In the other biotype, R1, DM penetration was significantly less than that observed in the resistant (R2 and R3) and susceptible (S) biotypes. Analysis of the leaf cuticle surface by scanning electron microscopy showed a greater epicuticular wax density in the leaf cuticles of biotype R1 than in the other biotypes.  相似文献   

Analysis of the influence of gully erosion in the flow pattern of catchment streams, Southeastern Brazil     

Fernanda Martineli Costa  Luis de Almeida Prado Bacellar   《CATENA》2007,69(3):230-238

The baseflow of tributaries to the Velhas River in the northwest region of Ouro Preto County (São Francisco Basin, Brazil) has been declining in the last years, without a simultaneous decrease in the water input. This can only be attributed to badly planned human activities, which result in soil crusting or compaction, erosion, among other types of impact, such as groundwater overexploitation and wetland drainage. Almost all of the study area has been eroded by hundreds of large-size gullies. In order to analyze the influence of erosion in the hydrological behavior of small streams, two similar and contiguous catchments were selected. The only remarkable difference between them is a gully that occupies circa 42% of one of the catchments (“eroded catchment”). Rainfall, flow rates and chemical data were obtained throughout a hydrological year and the results showed that the eroded catchment presented smaller baseflow rates and bigger but short-lived stormflows. This contrasting flow regime is attributed to the gully, which is causing the partial withdraw of the regolith and the exposure of weathered rock. As the regolith has smaller hydraulic conductivities and higher storage coefficients, the exposure of weathered rock on the gully floor explains the odd flow behavior of the eroded catchment. Other studies in the same region confirm the impact caused by the gullies. Thus, the superposition of many gullies can cause decrease of the baseflow and increase of the stormflow. As gullies are very common erosion features in Brazil, they should be much more studied in order to better understand this and other similar types of environmental impact.  相似文献   

Nitrate fate in a Mexican Andosol: Is it affected by preferential flow?     

B. Prado  C. Duwig 《Agricultural Water Management》2011,98(9):1441-1450

Andosols are the dominant soils in the Valle de Bravo basin, the origin of a significant amount of Mexico City's drinking water. The main land use is agriculture and most of the existing surface water bodies are eutrophic. Nitrogen fertilizer is used extensively. There have been very few studies on nitrate (NO₃⁻) fate in this type of soil and region. Comprehensive laboratory studies were conducted to determine the fate of NO₃⁻ in an Andosol profile from Valle de Bravo, in order to assess the risk of water resources contamination. Nitrate retention was analysed statically (using batch experiments) and dynamically (using intact and packed soil columns) at different soil depths and its competition with Cl⁻ was evaluated. Complementary laboratory experiments were conducted to study water transport through the columns and nitrogen transformations in the soil. In batch and columns, NO₃⁻ adsorption was linear in the range of concentrations studied and higher in the deepest soil layer. Preferential flow pathways were found in the unaltered deeper soil layers, while tillage activity in the top layer destroyed the pore continuity. In spite of the deeper soil layer's greater capacity for NO₃⁻ retention, the presence of preferential flow pathways coupled with high rainfall intensities, makes the NO₃⁻ mobile below the root zone at 1 m depth and increases the risk of groundwater contamination. The results illustrate the complexity of nitrate fate in Andosols and can be used to improve agricultural practices in the central Mexico region.  相似文献   

Prolactin: does it exert an up-modulation of the immune response in Trypanosoma cruzi-infected rats?     

Filipin Mdel V  Brazão V  Santello FH  Caetano LC  Toldo MP  do Prado JC 《Veterinary parasitology》2011,181(2-4):139-145

During the course of infection by Trypanosoma cruzi, the host immune system is involved in distinct, complex interactions with the endocrine system, and prolactin (PRL) is one of several hormones involved in immunoregulation. Although intensive studies attempting to understand the mechanisms that underlie Chagas' disease have been undertaken, there are still some pieces missing from this complex puzzle. Because data are scarce concerning the role of PRL involvement in Chagas' disease and taking into account the existence of crosstalk between neuroendocrine hormones and the immune system, the current study evaluates a possible up-regulation of the cellular immune response triggered by PRL in T. cruzi-infected rats and the role of PRL in reversing immunosuppression caused by the parasitic infection. The data shown herein demonstrate that PRL induces the proliferation of T lymphocytes, coupled with an activation of macrophages and the production of nitric oxide (NO), leading to a reduction in the number of blood trypomastigotes during the peak of parasitemia. During the acute phase of T. cruzi infection, an enhancement of both CD3+CD4+ and CD3+CD8+ T cell populations were observed in infected groups, with the highest numbers of these T cell subsets found in the infected group treated with PRL. Because NO is a signaling molecule involved in a number of cellular interactions with components of the immune system and the neuroendocrine system, PRL can be considered an alternative hormone able to up-regulate the host's immune system, consequently lowering the pathological effects of a T. cruzi infection.  相似文献