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971.
972.
Maple syrup urine disease (MSUD) is an inherited aminoacidopathy caused by a deficiency in branched-chain α-keto acid dehydrogenase complex activity that leads to the accumulation of the branched-chain amino acids (BCAAs) leucine (Leu), isoleucine, and valine and their respective α-keto-acids, α-ketoisocaproic acid (KIC), α keto-β-methylvaleric acid, and α-ketoisovaleric acid. The major clinical features presented by MSUD patients include ketoacidosis, failure to thrive, poor feeding, apnea, ataxia, seizures, coma, psychomotor delay, and mental retardation; however, the pathophysiology of this disease is poorly understood. MSUD treatment consists of a low protein diet supplemented with a mixture containing micronutrients and essential amino acids but excluding BCAAs. Studies have shown that oxidative stress may be involved in the neuropathology of MSUD, with the existence of lipid and protein oxidative damage in affected patients. In recent years, studies have demonstrated the antioxidant role of l-carnitine (l-Car), which plays a central function in cellular energy metabolism and for which MSUD patients have a deficiency. In this work, we investigated the in vitro effect of Leu and KIC in the presence or absence of l-Car on DNA damage in peripheral whole blood leukocytes using the alkaline comet assay with silver staining and visual scoring. Leu and KIC resulted in a DNA damage index that was significantly higher than that of the control group, and l-Car was able to significantly prevent this damage, mainly that due to KIC.  相似文献   
973.
Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) was used to examine genetic variation and population structure of screwworm flies in four populations from São Paulo State, Brazil. The total DNA of 405 individuals was digested with 15 restriction endonucleases and probed with five clonedHindIII fragments representing the entire mitochondrial genome ofCochliomyia hominivorax. The survey revealed that four enzymes (HaeIII,HindIII,MspI, andPvuII) were suitable to detect mtDNA variation among all populations. Based on the fragment patterns obtained for these four enzymes, a total of 15 haplotypes in combination was detected. Heteroplasmic individuals for thePvuII pattern were obtained in one of the populations. The estimated average for nucleotide sequence divergence (δ) was 0.92%. The cladogram of the geographical distribution among the observed haplotypes suggests that the sampled screwworms probably belong to a single evolutionary lineage with populations interconnected by reduced gene flow.  相似文献   
974.
Organ dysfunction is a major concern in sepsis pathophysiology and contributes to its high mortality rate. Neutrophil extracellular traps (NETs) have been implicated in endothelial damage and take part in the pathogenesis of organ dysfunction in several conditions. NETs also have an important role in counteracting invading microorganisms during infection. The aim of this study was to evaluate systemic NETs formation, their participation in host bacterial clearance and their contribution to organ dysfunction in sepsis. C57Bl/6 mice were subjected to endotoxic shock or a polymicrobial sepsis model induced by cecal ligation and puncture (CLP). The involvement of cf-DNA/NETs in the physiopathology of sepsis was evaluated through NETs degradation by rhDNase. This treatment was also associated with a broad-spectrum antibiotic treatment (ertapenem) in mice after CLP. CLP or endotoxin administration induced a significant increase in the serum concentrations of NETs. The increase in CLP-induced NETs was sustained over a period of 3 to 24 h after surgery in mice and was not inhibited by the antibiotic treatment. Systemic rhDNase treatment reduced serum NETs and increased the bacterial load in non-antibiotic-treated septic mice. rhDNase plus antibiotics attenuated sepsis-induced organ damage and improved the survival rate. The correlation between the presence of NETs in peripheral blood and organ dysfunction was evaluated in 31 septic patients. Higher cf-DNA concentrations were detected in septic patients in comparison with healthy controls, and levels were correlated with sepsis severity and organ dysfunction. In conclusion, cf-DNA/NETs are formed during sepsis and are associated with sepsis severity. In the experimental setting, the degradation of NETs by rhDNase attenuates organ damage only when combined with antibiotics, confirming that NETs take part in sepsis pathogenesis. Altogether, our results suggest that NETs are important for host bacterial control and are relevant actors in the pathogenesis of sepsis.  相似文献   
975.
976.
Muscle-type LDH (LDH-m4) activity is critical for efficient anaerobic glycolysis. The results here show that rabbit LDH-M4 is inhibited by concentrations of ascorbate normally found in tissues. Aldolase and muscle G-actin were found to protect and to reverse inhibitions of LDH-m4 by ascorbate. G-actins showed some species specificity. Myosin, tropomyosin and troponin from rabbit muscle and muscle proteins from other animal sources had no affect on the inhibitions by ascorbate. The substrate inhibition of LDH-m4 by pyruvate is partially relieved by the presence of aldolase and lowers the Km without affecting the Vm. G-actin under similar conditions has no affect. It is believed that these studies reflect some of the resting properties of glycolytic enzymes that bind and unbind to contractile elements. It is proposed that ascorbate facilitates the storage of glycogen in muscle at rest by inhibiting glycolysis.  相似文献   
977.
Crop production may benefit from plant growth-promoting bacteria. The knowledge on bacterial communities is indispensable in agricultural systems that intend to apply beneficial bacteria to improve plant health and production of crops such as canola. In this work, the diversity of root bacterial communities associated to two different developmental phases of canola (Brassica napus L.) plants was assessed through the application of new generation sequencing technology. Total bacterial DNA was extracted from root samples from two different growth states of canola (rosette and flowering). It could be shown how bacterial communities inside the roots changed with the growing stage of the canola plants. There were differences in the abundance of the genera, family, and even the phyla identified for each sample. While in both root samples Proteobacteria was the most common phylum, at the rosette stage, the most common bacteria belonged to the family Pseudomonadaceae and the genus Pseudomonas, and in the flowering stage, the Xanthomonadaceae family and the genus Xanthomonas dominated the community. This implies in a switch in the predominant bacteria in the different developmental stages of the plant, suggesting that the plant itself interferes with the associated microbial community.  相似文献   
978.
Motility plays an essential role in bacterial fitness and colonization in the plant environment, since it favors nutrient acquisition and avoidance of toxic substances, successful competition with other microorganisms, the ability to locate the preferred hosts, access to optimal sites within them, and dispersal in the environment during the course of transmission. In this work, we have observed that the mutation of the flagellar master regulatory gene, fleQ, alters bacterial surface motility and biosurfactant production, uncovering a new type of motility for Pseudomonas syringae pv. tomato DC3000 on semisolid surfaces. We present evidence that P. syringae pv. tomato DC3000 moves over semisolid surfaces by using at least two different types of motility, namely, swarming, which depends on the presence of flagella and syringafactin, a biosurfactant produced by this strain, and a flagellum-independent surface spreading or sliding, which also requires syringafactin. We also show that FleQ activates flagellum synthesis and negatively regulates syringafactin production in P. syringae pv. tomato DC3000. Finally, it was surprising to observe that mutants lacking flagella or syringafactin were as virulent as the wild type, and only the simultaneous loss of both flagella and syringafactin impairs the ability of P. syringae pv. tomato DC3000 to colonize tomato host plants and cause disease.  相似文献   
979.
In two consecutive years, we analysed the effect of litter quality, quantity and decomposability on soil N at three characteristic sites of the Patagonian Monte. We assessed (i) concentrations of N, C, lignin and total phenolics and the C/N ratio in senesced leaves as indicators of litter quality of three species of each dominant plant life form (evergreen shrubs and perennial grasses), and (ii) N, and organic-C concentrations, potential N-mineralisation and microbial-N flush in the soil beneath each species. Rate constants of potential decomposition of senesced leaves and N content in decaying leaves during the incubation period were assessed in composite samples of the three sites as indicators of litter decomposability. Further, we estimated for each species leaf-litter production, leaf-litter on soil, and the mass of standing senesced leaves during the senescence period. Senesced leaves of evergreen shrubs showed higher decomposability than those of perennial grasses. Leaf-litter production, leaf-litter on soil, and the mass of standing senesced leaves differed significantly among species. The largest variations in leaf-litter production and leaf-litter on soil were observed in evergreen shrubs. The mass of standing senesced leaves was larger in perennial grasses than in evergreen shrubs. Nitrogen, organic C and potential N-mineralisation in soil were higher underneath evergreen shrubs than beneath perennial grasses, while no significant differences were found in microbial-N flush among life forms. The initial concentrations of C, N and total phenolics of senesced leaves explained together 78% of the total variance observed in the dry mass loss of decaying leaves. Litter decomposition rates explained 98%, 98%, 73%, and 67% of the total variance of soil N, organic C, net-N mineralisation, and microbial-N flush, respectively. We concluded that leaf-litter decomposition rates along with leaf-litter production are meaningful indicators of plant local effects on soil N dynamics in shrublands of the Patagonian Monte, and probably in other similar ecosystem of the world dominated by slow growing species that accumulate a wide variety of secondary metabolites including phenolics. Indicators such as C/N or lignin concentration usually used to predict litter decomposability or local plant effects may not be adequate in the case of slow growing species that accumulate a wide range of secondary metabolites or have long leaf lifespan and low leaf-litter production.  相似文献   
980.
Population genetic structuring is common among herbivorous insects and frequently is associated with divergent host plants, such as crops and their wild relatives. Previous studies showed population genetic structuring in corn leafhopper Dulbulus maidis in Mexico, such that the species consists of two sympatric, host plant-associated populations: an abundant and widespread "pestiferous” population on maize (Zea mays mays), and a small and localized "wild" population on perennial teosinte (Zea diploperennis). a maize wild relative with a limited distribution. This study addressed whether assortative mating and immigrant inviability mediate genetic structuring of corn leafliopper by comparing the mating and reproductive successes of pestiferous and wild females that colonize their nonassociated host plants against the successes of females colonizing their associated host plants. Assortative mating was assessed by comparing mating frequencies and premating and mating times among females of each population on each host plant: immigrant inviability was assessed by comparing, across two generations, the fecundity, survival, development time, sex ratio, and population growth rate among leafhopper populations and host plants. Our results showed that on maize, and compared to resident, pestiferous females, wild females were more likely to mate, and greater proportions of their offspring survived to adult stage and were daughters;consequently, the per-generation population growth rate on maize was greater for immigrant, wild leafhoppers compared to resident, pestiferous leafhoppers. Our results suggested that wild leafhoppers emigrating to maize have a fitness advantage over resident, pestiferous leafhoppers, while immigrant pestiferous and resident wild leafhoppers on teosinte have similar fitnesses.  相似文献   
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