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61.
62.
Toll-like receptors (TLRs) and β-defensins are important components of the innate immune system. This study aimed to evaluate endometrial mRNA levels of TLRs (1/6, 2, 4, and 5) and β-defensin 5 in Holstein cows by quantitative real time RT-PCR. Uterine biopsies were performed from 6 to 12 h after parturition, and cows were divided into two groups: (i) cows with placental retention and clinical signs of uterine infection until 45 days postpartum (n=10) or (ii) cows with normal puerperium (n=10). All cows had detectable levels of TLRs and β-defensin 5 mRNAs, but these levels did not differ between groups (P>0.05). Levels of TLR4 mRNA had a positive and significant correlation with the time required for uterine involution in both groups.  相似文献   
63.
During the last decade the majority of diphtheria cases in Europe had Corynebacterium ulcerans as the etiologic agent with dogs and cats as the reservoir hosts. However, little has been documented about the virulence factors of this zoonotic pathogen. To set up an in vivo experimental C. ulcerans infection model, conventional Swiss Webster mice were intravenously infected with different doses (from 1 × 10(7) to 5 × 10(9) bacteria per mouse) of C. ulcerans strains, namely 809 (from human lower respiratory tract), BR-AD22 (from asymptomatic dog nares) and CDC-KC279. Mortality rates were demonstrated by LD(50) values ranging from 1.9 × 10(8) to 1.3 × 10(9). Viable bacteria were recovered from blood, kidneys, liver, spleen and joints. For CDC-KC279 and 809 strains (2 × 10(8)mL(-1)) approximately 85% and 72% of animals with articular lesions were observed, respectively; BR-AD22-infected mice showed no signs of arthritis. CDC-KC279 and 809 strains exhibited higher arthritogenic potential when compared to the homologous toxigenic (ATCC27012) and non-toxigenic (ATCC27010) strains of Corynebacterium diphtheriae. A high number of affected joints and arthritis index in addition to the histopathological features, including subcutaneous edema, inflammatory infiltrate, damage to bone tissue and synoviocyte hypertrophy, indicated a strain-dependent ability of C. ulcerans strains to cause severe polyarthritis. A correlation between the arthritis index and systemic levels of IL-6 and TNF-α was observed for C. ulcerans strains, with the exception of the non-arthritogenic BR-AD22 strain. In conclusion, C. ulcerans revealed a strain-dependent arthritogenic potential independent of DNAse, PLD and diphtheria toxin production.  相似文献   
64.
Maternal cytokines may play instructive roles in development of the neonatal immune system. However, cytokines in colostrum and milk and their transfer from mothers to neonates have not been well documented, except for TGF-beta. Swine provide a unique model to study lactogenic cytokines because the sow's impermeable placenta prohibits transplacental passage. We investigated IL-6 and TNF-alpha (pro-inflammatory), IFN-gamma and IL-12 (Th1), IL-10 and IL-4 (Th2) and TGF-beta1 (Th3) concentrations in sow serum and colostrum/milk and serum of their suckling and weaned piglets and in age-matched colostrum-deprived gnotobiotic piglets. All cytokines were detected in colostrum/milk and correlated with concentrations in sow serum except for mammary-derived TNF-alpha and TGF-beta1. Detection of IL-12 and TGF-beta1 in pre-suckling and colostrum-deprived gnotobiotic piglet serum suggests constitutive production: other cytokines were undetectable confirming absence of transplacental transfer. Peak median cytokine concentrations in suckling piglet serum occurred at post-partum days 1-2 (IL-4>IL-6>IFN-gamma>IL-10). The effects in vitro of physiologically relevant concentrations of the two predominant lactogenic cytokines (TGF-beta1 and IL-4) on porcine naive B cell responses to lipopolysaccharide (LPS) and rotavirus (RV) were investigated. High (10 ng/ml) TGF-beta1 suppressed immunoglobulin secreting cell responses to LPS and rotavirus; low concentrations (0.1 ng/ml) promoted isotype switching to IgA antibody. Interleukin-4 induced inverse dose-dependent (0.1 ng>10 ng/ml) isotype switching to IgA and enhanced IgM secreting cell responses to LPS and rotavirus. In summary, we documented the transfer and persistence of maternal cytokines from colostrum/milk to neonates and their potential role in Th-2 biased IgA responses and reduced immunologic responsiveness of neonates.  相似文献   
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The effects of bovine leukemia virus (BLV) on the immune response have been extensively investigated; however, its effects on mammary gland immunity are only speculative. Although BLV has a tropism for B cells, it can affect both adaptive and innate immunities because these systems share many effector mechanisms. This scenario is the basis of this investigation of the effects of BLV on mammary gland immunity, which is largely dependent upon neutrophilic functions. Thus, the present study sought to examine neutrophilic functions and the lymphocyte profile in the milk of naturally BLV-infected cows. The viability of the milk neutrophils and the percentage of milk neutrophils that produced reactive oxygen species (ROS) or phagocytosed Staphylococcus aureus were similar between BLV-infected and BLV-uninfected dairy cows. Furthermore, the expression of CD62L and CD11b by the milk neutrophils and the percentage of milk neutrophils (CH138+ cells) that were obtained from the udder quarters of the BLV-infected cows were not altered. Conversely, the median fluorescence intensity (MFI) representing intracellular ROS production and the phagocytosis of S. aureus, the expression of CD44 by the milk neutrophils and the percentage of apoptotic B cells were lower in the milk cells from BLV-infected dairy cows, particularly those from animals with persistent lymphocytosis (PL). The lymphocyte subsets were not different among the groups, with the exception of the percentage of CD5/CD11b B cells, which was higher in the milk cells from BLV-infected cows, particularly those with PL. Thus, the present study provides novel insight into the implications of BLV infection for mammary gland immunity.  相似文献   
67.

Accurate estimation of biomass in natural vegetation sites remains a challenge. Modeling biomass growth and production in Cerrado areas is crucial to understanding the vegetation succession process, especially regarding the changes in biomass accumulation over time. Thus, our objective was to model the growth and production of woody aboveground biomass (living and total) in a cerrado stricto sensu monitored for 27 years after implementing management systems. As expected, the basal area (with a diameter taken at 30 cm from the ground level) is the most important predictor variable and showed a higher correlation with the biomass stocks and allowed accurate and consistent estimates of these accumulated stocks over time. Future estimates of biomass production, generated from growth models that estimate production as a function of parameters observed at previous ages, indicate that maximum stocks of living (25.86?±?0.15 Mg ha?1 [mean?±?standard deviation]) and total aboveground biomass (26.11?±?0.15 Mg ha?1) are expected for a period between 28 and 30 years after the implementation of the management systems, with maximum mean annual increment between 23 and 27 years. Furthermore, the systems of equations obtained simulated reductions up to 30% of biomass after the occurrence of a forest fire at 23 years. Thus, our study can be useful for the decision-making process and developing public policies and strategies for managing and conserving natural resources in the Cerrado biome.

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68.
Euphytica - Head splitting is a major physiological disease in cabbage. The most effective approach for controlling head splitting is to deploy genetic resistance by breeding cabbage cultivars with...  相似文献   
69.
A study was conducted on the effect of nitrate (NO3) levels on nitrate uptake kinetics and nitrogen (N) metabolism in two rice varieties, Piaui (landrace) and IAC-47 (improved). At 27 days after germination (DAG) N supply was suspended for 72 h, and then restored as 0.2 or 2 mM nitrate. The nitrate uptake kinetics was determined by the depletion method. Plants were harvested at 0, 6, and 24 h. Plants of the Piaui variety under 0.2 mM nitrate showed higher Vmax and lower KM, indicating higher efficiency of nitrate uptake at low supply. In the sheaths of both varieties, there was a greater accumulation of nitrate and lower activities of nitrate reductase and glutamine synthetase. The V-H+-ATPase activity increased between 0 and 6 h accompanying the nitrate influx, suggesting that the activity of this proton pump is necessary for the antiport activity (H+/2NO? 3) involved in the accumulation of nitrate into vacuoles.  相似文献   
70.
Abstract

Several studies have shown hydrogen peroxide (H2O2) as a metabolic messenger that increases plant tolerance to various stress conditions. However, little is known about its effect on the mobilization of seed reserves in the establishment of seedlings. Thus, this study aimed to evaluate the effect of pretreatment with H2O2 in salt-tolerance and mobilization of reserves during the germination of seeds and establishment of sunflower seedlings. Seeds were pre-imbibed for 24?hr in solutions containing: deionized water (control); H2O2 (1?mM); NaCl (100?mM). Subsequently, seeds were distributed on germitest paper, moistened with deionized water or saline solution (100?mM NaCl). In seedlings not pretreated with H2O2, the salinity increased Na+ and Cl? ions contents and reduced the growth of sunflower seedlings. However, pretreatment of seeds with H2O2 reduced the negative effect of salinity, promoted an increase in salt-tolerance by the reduction of Na+ and Cl? uptake, lower energy cost for osmoprotection by compatible solutes accumulation, and by the higher equilibrium in the mobilization of the cotyledon reserves for the development of the embryonic axis.  相似文献   
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