Arbuscular mycorrhizal root colonization and soil P availability are positively related to agrodiversity in Mexican maize polycultures     

Simoneta Negrete-Yankelevich  Ignacio Eduardo Maldonado-Mendoza  Jesús Omar Lázaro-Castellanos  Wendy Sangabriel-Conde  Juan Carlos Martínez-Álvarez 《Biology and Fertility of Soils》2013,49(2):201-212

In Los Tuxtlas, Mexico, the local Popoluca people maintain the traditional management of their maize agroecosystems. However, it is not known whether the loss of agrodiversity over recent decades has affected mycorrhizal populations, nutrient availability, and crop productivity. This study utilized linear mixed effect models to analyze the relationship between agrodiversity (three, six, and greater than or equal to eight cultivated species) and (a) arbuscular mycorrhizal fungi (AMF) inoculum potential, measured as the most probable number (MPN) of propagules and colonization level, (b) nutrient availability, and (c) aboveground maize productivity. We also investigated the relationship between soil nutrient content and inoculum potential. Soil samples were taken before planting, and during flowering, in the 2009 maize cycle. We found that AMF colonization level of maize roots and P availability increased with planted species richness, but that this effect only occurred at the flowering sampling date. Plots with a higher MPN of propagules presented increased C and NO ₃ ^? contents and lower C/N ratio than those with lower MPN of propagules, regardless of agrodiversity. Soils that produced the highest maize root colonization level also featured high P availability and N content. We conclude that decreased agrodiversity in these traditional systems does not significantly affect the soil MPN of propagules, but may have a negative impact on the ability of the mycorrhizal community to colonize maize roots, as well as reducing the availability of P, which is often the most limiting nutrient in tropical soils.  相似文献   

Effects of Fusicoccin and Vanadate on Proton Extrusion and Potassium Uptake by Rice     

Carlos Alberto Bucker  Sonia Regina de Souza  Manlio Silvestre Fernandes 《Journal of plant nutrition》2013,36(3):485-496

The effects of fusicoccin or vanadate on proton (H⁺) extrusion and potassium (K) uptake of four varieties of rice (oryza satiya L.) were studied. Two of them were improved varieties (IAC-47 and Agulha), with 70% genetic similarity. The two others were landraces (Bico Ganga and Piaui). Vanadate totally blocked H⁺-pumping activity while fusicoccin increased it. Potassium uptake was suppressed under vanadate but increased sharply under the fusicoccin treatment. The Piaui was the most affected by fusicoccin, while Agulha was the least affected. Under fusicoccin, Bico Ganga had a 48% increase in K uptake at the end of the experimental period in relation to the controls, while IAC-47 showed only a 17% increase. Taken together, for all varieties and treatments, there was a negative correlation between the final pH and the total K taken up by plants. This study suggests that some rice varieties need additional stimulation from external sources to express their full H⁺-pumping and K-uptake capabilities.  相似文献   

High K+ supply avoids Na+ toxicity and improves photosynthesis by allowing favorable K+ : Na+ ratios through the inhibition of Na+ uptake and transport to the shoots of Jatropha curcas plants     

Cicera Raquel Fernandes Rodrigues  Evandro Nascimento Silva  Sérgio Luiz Ferreira‐Silva  Eduardo Luiz Voigt  Ricardo Almeida Viégas  Joaquim Albenisio Gomes Silveira 《植物养料与土壤学杂志》2013,176(2):157-164

This study assessed the relationships between external K⁺ supply and K⁺ : Na⁺ ratios associated with Na⁺ toxicity in Jatropha curcas. Plants were exposed to increasing external K⁺ concentrations (6.25, 12.5, 25, 37.5, and 50 mM), combined with 50 mM NaCl in a nutrient solution. Photosynthesis progressively increased as the external K⁺ : Na⁺ ratios increased up to 0.75. The increase of photosynthesis and plant dry matter correlated positively with K⁺ : Na⁺ in xylem and leaves. The transport rates of K⁺ and Na⁺ from roots to xylem and leaves were inversely correlated. These ions presented an antagonistic pattern of accumulation in all organs. Maximum rates of photosynthesis and plant growth occurred with leaf K⁺ : Na⁺ ratios that ranged from 1.0 to 2.0, indicating that this parameter in leaves might be a good indicator for a favorable K⁺ homeostasis under salinity conditions. The higher K⁺ affinity and selectivity compared with Na⁺ in all organs associated with higher xylem flux and transport to shoots are essential for maintaining adequate K⁺ : Na⁺ ratios at the whole‐plant level. These characteristics, combined with adequate K⁺ concentrations, allow J. curcas to sustain high rates of photosynthesis and growth even under toxic NaCl levels.  相似文献   

Colletotrichum gloeosporioides sensu lato associated with anthracnose in Bauhinia forficata     

de Souza Junior  Francisco Jorge Carlos  dos Santos Vieira  Willie Anderson  Veloso  Josiene Silva  Duarte  Ingrid Gomes  Amaral  Ana Gabriele Gurgel  Laranjeira  Delson  Balbino  Valdir De Queiroz  Doyle  Vinson P.  Câmara  Marcos Paz Saraiva 《European journal of plant pathology / European Foundation for Plant Pathology》2021,160(3):745-751

European Journal of Plant Pathology - Bauhinia forficata is an important plant commonly used in traditional medicine, and as an ornamental plant in parks and gardens. Its use as an ornamental plant...  相似文献   

Impact of Community Forest Management on Biomass Carbon Stocks in the Uatumã Sustainable Development Reserve,Amazonas, Brazil     

André Luiz Menezes Vianna  Philip Martin Fearnside 《Journal of Sustainable Forestry》2013,32(2):127-151

Forest management can result in net losses of carbon stock. To quantify the impact of the management it is important to assess losses or gains of carbon, as well as the sustainability of the management system. This study quantified the impact management under a Small-Scale Sustainable Forest Management Plan, which is a recently created category of authorized management for small managers in the state of Amazonas, Brazil. Impact was quantified on the number of individuals, the biomass of natural regeneration, and the damage to the remaining trees 2 months after logging. The impact of these changes on carbon stock was estimated. The study was carried out in the Uatumã Sustainable Development Reserve, Amazonas, Brazil, where two areas of small-scale forest management and one control were evaluated. Average total carbon stock previous to logging was estimated at 161.25 ± 9.66 MgC ha^?1. Two months after logging, reductions were found of 3% in one managed area (MA1) and 8.3% in the other (MA3), including the carbon stock from the harvested timber. For each harvested tree, the logging caused damage to 12 trees in MA1 and four trees in MA3. The reductions in carbon stock and number of trees damaged per harvested tree were less than the reductions found for higher impact forest management and other experiences in community forest management. No significant alteration was found in the carbon stock of natural regeneration. However, there was an increase in the number of individuals, both in the logged areas and in their respective control areas.  相似文献   

Predictive value of prepartum serum metabolites for incidence of clinical and subclinical mastitis in grazing primiparous Holstein cows     

Elizabeth Schwegler  Augusto Schneider  Paula Montagner  Diego Andres Velasco Acosta  Luiz Francisco Machado Pfeifer  Eduardo Schmitt  Viviane Rohrig Rabassa  Francisco Augusto Burkert Del Pino  Helenice de Lima Gonzalez  Cláudio Dias Timm  Marcio Nunes Corrêa 《Tropical animal health and production》2013,45(7):1549-1555

The aim of this study was to measure changes in biochemical markers in the peripartum period of primiparous Holstein cows diagnosed with subclinical and clinical mastitis. In this study, 37 dairy cows were monitored daily during milking until 60 days postpartum and were categorized according to the occurrence of clinical mastitis (group mastitis (GM), n?=?9) or subclinical mastitis (group subclinical mastitis (GSUB), n?=?10) or absence of symptoms (control group (CG), n?=?18). Blood samples were collected weekly from ?30 to 60 days from calving. Samples were grouped for prepartum (?30 to 0 days from calving), early postpartum (0 to 30 days from calving), and late postpartum (30 to 60 days from calving) periods. Prepartum serum non-esterified fatty acid (NEFA) concentration was higher in GM than in CG (P?<?0.01). In addition, CG had higher prepartum serum glucose concentration than GM (P?=?0.03). In the early postpartum period, aspartate aminotransferase (AST) activity was lower in CG than in GSUB (P?<?0.05), and in the late postpartum period, AST activity was lower in CG than GSUB and GM (P?=?0.01). Somatic cell count was higher during the early and late postpartum periods for GM and GSUB when compared to CG (P?<?0.01). In this study, primiparous cows with low glucose and higher NEFA in the prepartum were more susceptible for mastitis in the early postpartum, probably due to low immune function associated to a more negative energy balance. In sum, increased prepartum serum NEFA concentration and decreased glucose in primiparous cows were associated with clinical mastitis incidence in the postpartum period.  相似文献   

Antimicrobial resistance and molecular epidemiology of streptococci from bovine mastitis     

Márcia G. Rato  Ricardo Bexiga  Carlos Florindo  Lina M. Cavaco  Cristina L. Vilela  Ilda Santos-Sanches 《Veterinary microbiology》2013,161(3-4):286-294

Streptococcus agalactiae (Group B Streptococcus, GBS), Streptococcus dysgalactiae subsp. dysgalactiae (Group C Streptococcus, GCS) and Streptococcus uberis are relevant mastitis pathogens, a highly prevalent and costly disease in dairy industry due to antibiotherapy and loss in milk production. The aims of this study were the evaluation of antimicrobial drug resistance patterns, particularly important for streptococcal mastitis control and the identification of strain molecular features. Antimicrobial resistance was assessed by disk diffusion against amoxicillin–clavulanic acid, cefazolin, cefoperazone, pirlimycin-PRL, rifaximin, streptomycin, chloramphenicol, erythromycin-ERY, gentamicin, tetracycline-TET and vancomycin. Genotypic relationships were identified using pulsed-field gel electrophoresis (PFGE), macrolide and/or tetracycline resistance gene profiling, GBS capsular typing, GBS virulence gene profiling and GBS and S. uberis multi locus sequence typing (MLST).The majority of the isolates were susceptible to all drugs except to aminoglycoside, macrolide, lincosamide and tetracycline. Close to half of the TET resistant isolates have tetO and tetK and almost all ERY–PRL resistant isolates have ermB. A high degree of intra-species polymorphism was found for GCS. The GBS belonged to ST-2, -554, -61, -23 lineages and five new molecular serotypes and human GBS insertion sequences in the cpsE gene were found. Also, GBS of serotype V with scpB and lmb seem to be related with GBS isolates of human origin (same ST-2 and similar PFGE). Overall our results suggested that different therapeutic programs may have been implemented in the different farms and that in most cases clones were herd-specific.  相似文献   

IGF-I,GHR and UCP mRNA expression in the liver and muscle of high- and low-feed-efficiency laying Japanese quail at different environmental temperatures     

Eliane Gasparino  Débora Marques Voltolini  Ana Paula Del Vesco  Simone Eliza Facioni Guimarães  Carlos Souza do Nascimento  Adhemar Rodrigues de Oliveira Neto 《Livestock Science》2013,157(1):339-344

In this study, we analyzed insulin-like growth factor I (IGF-I), growth hormone receptor (GHR) and uncoupling protein (UCP) mRNA expression in the muscle and liver of high- (0.23 g/g) and low- (0.17 g/g) feed-efficiency (FE) Japanese quail at three different air temperatures: comfortable (25 °C), heat stress (38 °C) for 12 h or cold stress (10 °C) for 12 h. Total RNA was extracted from the liver and breast muscle of each quail, and cDNA was amplified using specific primers for the target genes. Expression was analyzed using quantitative real-time PCR (qRT-PCR). IGF-I mRNA expression was higher in the livers of high-FE quail than in the livers of low-FE quail under both heat and cold stress conditions. High-FE birds also showed higher GHR mRNA expression independent of temperature. UCP mRNA expression in the liver was lower in high-FE birds and higher under heat stress compared with the other conditions. IGF-I mRNA expression was higher in the muscle of high-FE quail under the three conditions tested, and UCP mRNA expression was higher under cold stress. Our results suggest that air temperature affects the expression of genes related to growth and mitochondrial energy production, and quail with different feed efficiencies respond differently to environmental stimuli.  相似文献   

Use of Infrared Thermography to Detect Intrasynovial Injections in Horses     

Tatiana FigueiredoBruna Dzyekanski  DVM  Cláudia T. PimpãoAndressa B. Silveira  DVM  PhD  Luiz G. CapriglionePedro Vicente Michelotto Jr.  DVM  MSc  PhD 《Journal of Equine Veterinary Science》2013

Athletic horses often experience painful conditions of the musculoskeletal system, but their ability to compete can be prolonged using certain anesthetic agents. The present study investigated the ability of thermography to detect fetlock and middle carpal intrasynovial injections of bupivacaine hydrochloride in five mares. Saline injections were performed in the contralateral limbs. Thermographic evaluation was conducted at the dorsal and palmar aspects before (basal) and 15, 30, 60, 90, 120, and 1440 minutes after injection. The intrasynovial treatments resulted in increased limb temperature, with fetlock temperatures higher on the dorsal aspect at 15, 30, and 60 minutes and on the palmar aspect from 15 to 1440 minutes (P < .05) after the bupivacaine and saline injections. Increased carpal temperature was detected on the dorsal aspect at 60 and 90 minutes (P < .05). The present study demonstrates that thermography can be used to detect intrasynovial injections in horses.  相似文献   

Chickens treated with a nitric oxide inhibitor became more resistant to Plasmodium gallinaceum infection due to reduced anemia,thrombocytopenia and inflammation     

Barbarella Matos de Macchi  Farlen José Bebber Miranda  Fernanda Silva de Souza  Eulógio Carlos Queiroz de Carvalho  Ant?nio Peixoto Albernaz  José Luiz Martins do Nascimento  Renato Augusto DaMatta 《Veterinary research》2013,44(1):8

Malaria is a serious infectious disease caused by parasites of the Plasmodium genus that affect different vertebrate hosts. Severe malaria leads to host death and involves different pathophysiological phenomena such as anemia, thrombocytopenia and inflammation. Nitric oxide (NO) is an important effector molecule in this disease, but little is known about its role in avian malaria models. Plasmodium gallinaceum- infected chickens were treated with aminoguanidine (AG), an inhibitor of inducible nitric oxide synthase, to observe the role of NO in the pathogenesis of this avian model. AG increased the survival of chickens, but also induced higher parasitemia. Treated chickens demonstrated reduced anemia and thrombocytopenia. Moreover, erythrocytes at different stages of maturation, heterophils, monocytes and thrombocytes were infected by Plasmodium gallinaceum and animals presented a generalized leucopenia. Activated leukocytes and thrombocytes with elongated double nuclei were observed in chickens with higher parasitemia; however, eosinophils were not involved in the infection. AG reduced levels of hemozoin in the spleen and liver, indicating lower inflammation. Taken together, the results suggest that AG reduced anemia, thrombocytopenia and inflammation, explaining the greater survival rate of the treated chickens.  相似文献