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51.
Competence-induced cells of Streptococcus pneumoniae lyse competence-deficient cells of the same strain during cocultivation
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Several streptococcal species are able to take up naked DNA from the environment and integrate it into their genomes by homologous recombination. This process is called natural transformation. In Streptococcus pneumoniae and related streptococcal species, competence for natural transformation is induced by a peptide pheromone through a quorum-sensing mechanism. Recently we showed that induction of the competent state initiates lysis and release of DNA from a subfraction of the bacterial population and that the efficiency of this process is influenced by cell density. Here we have further investigated the nature of this cell density-dependent release mechanism. Interestingly, we found that competence-induced pneumococci lysed competence-deficient cells of the same strain during cocultivation and that the efficiency of this heterolysis increased as the ratio of competent to noncompetent cells increased. Furthermore, our results indicate that the lysins made by competent pneumococci are not released into the growth medium. More likely, they are anchored to the surface of the competent cells by choline-binding domains and cause lysis of noncompetent pneumococci through cell-to-cell contact. 相似文献
52.
Bruun JM Lihn AS Verdich C Pedersen SB Toubro S Astrup A Richelsen B 《American journal of physiology. Endocrinology and metabolism》2003,285(3):E527-E533
Adiponectin is an adipose tissue-specific protein that is abundantly present in the circulation and suggested to be involved in insulin sensitivity and development of atherosclerosis. Because cytokines are suggested to regulate adiponectin, the aim of the present study was to investigate the interaction between adiponectin and three adipose tissue-derived cytokines (IL-6, IL-8, and TNF-alpha). The study was divided into three substudies as follows: 1) plasma adiponectin and mRNA levels in adipose tissue biopsies from obese subjects [mean body mass index (BMI): 39.7 kg/m2, n = 6] before and after weight loss; 2) plasma adiponectin in obese men (mean BMI: 38.7 kg/m2, n = 19) compared with lean men (mean BMI: 23.4 kg/m2, n = 10) before and after weight loss; and 3) in vitro direct effects of IL-6, IL-8, and TNF-alpha on adiponectin mRNA levels in adipose tissue cultures. The results were that 1) weight loss resulted in a 51% (P < 0.05) increase in plasma adiponectin and a 45% (P < 0.05) increase in adipose tissue mRNA levels; 2) plasma adiponectin was 53% (P < 0.01) higher in lean compared with obese men, and plasma adiponectin was inversely correlated with adiposity, insulin sensitivity, and IL-6; and 3) TNF-alpha (P < 0.01) and IL-6 plus its soluble receptor (P < 0.05) decreased adiponectin mRNA levels in vitro. The inverse relationship between plasma adiponectin and cytokines in vivo and the cytokine-induced reduction in adiponectin mRNA in vitro suggests that endogenous cytokines may inhibit adiponectin. This could be of importance for the association between cytokines (e.g., IL-6) and insulin resistance and atherosclerosis. 相似文献
53.
García-Valdés E Castillo MM Bennasar A Guasp C Cladera AM Bosch R Engesser KH Lalucat J 《Systematic and applied microbiology》2003,26(3):390-403
Strain CLN100 was isolated after enrichment on mineral medium with chloronaphthalene as the only carbon and energy source. It was able to use simultaneously and productively chloro- and methyl-derivatives of naphthalene and salicylate through a chromosomally encoded meta pathway. Phenotypic, chemotaxonomic and genotypic characterization classified strain CLN100 as a member of the species Pseudomonas stutzeri. DNA-DNA hybridizations, 16S rDNA, gyrB, rpoD sequences, and molecular fingerprinting indicate that strain CLN100 is a representative of a new genomovar (genomovar 10) within the species. 相似文献
54.
The effect of feeding Lactobacillus fermentum I5007 on the immune system of weaned pigs with or without E. coli challenge was determined. Twenty-four weaned barrows (6.07 ± 0.63 kg BW) were randomly assigned to one of four treatments
(N = 6) in a factorial design experiment. The first two treatments consisted of healthy piglets with half of the pigs receiving
no treatment while the other half was orally administered with L. fermentum I5007 (108 CFU/ml) at a daily dose of 20 ml. Pigs in the second two treatments were challenged on the first day with 20 ml of E. coli K88ac (108 CFU/ml). Half of these pigs were not treated while the remaining pigs were treated with 20 ml of L. fermentum I5007 (108 CFU/ml). Peripheral blood lymphocytes subsets were determined using flow cytometry. The intestinal mucosal immunity of the
pigs was monitored by real time polymerase chain reaction. The cytokine content of the pig’s serum was also analyzed. Oral
administration of L. fermentum I5007 increased blood CD4+ lymphocyte subset percentage as well as tumor necrosis factor-α and interferon-γ expression in the ileum. Pigs challenged
with E. coli had elevated jejunal tumor necrosis factor-α while interferon-γ expression was increased throughout the small intestine.
There was no difference in the concentration of the cytokines interleukin-2, interleukin-6, tumor necrosis factor-α and interferon-γ
in the serum. CD8+ and CD4+/CD8+ in peripheral blood were not affected by treatment. In conclusion, L. fermentum I5007 can enhance T cell differentiation and induce ileum cytokine expression suggesting that this probiotic strain could
modulate immune function in piglets. 相似文献
55.
中药王不留行化学成分的研究Ⅲ 总被引:3,自引:0,他引:3
从经产麦蓝菜(Vaccaria segetalis(Neck)Garche.)的种子王不留行中分离得到5个化合物,经波谱分析和化学方法分别鉴定为化学方法分别鉴定为:VaccarosideB(1)、C(2)、D、(3),6-N-methyladenosine(4)和N,N-dimethyl-L-tryptophan(5)。其中化合物4和5为首次从该植物中分得。 相似文献
56.
Aina E. Prinzenberg Lucia Campos-Dominguez Willem Kruijer Jeremy Harbinson Mark G. M. Aarts 《Plant, cell & environment》2020,43(8):2000-2013
Low, but non-freezing, temperatures have negative effects on plant growth and development. Despite some molecular signalling pathways being known, the mechanisms causing different responses among genotypes are still poorly understood. Photosynthesis is one of the processes that are affected by low temperatures. Using an automated phenotyping platform for chlorophyll fluorescence imaging the steady state quantum yield of photosystem II (PSII) electron transport (ΦPSII) was measured and used to quantify the effect of moderately low temperature on a population of Arabidopsis thaliana natural accessions. Observations were made over the course of several weeks in standard and low temperature conditions and a strong decrease in ΦPSII upon the cold treatment was found. A genome wide association study identified several quantitative trait loci (QTLs) that are associated with changes in ΦPSII in low temperature. One candidate for a cold specific QTL was validated with a mutant analysis to be one of the genes that is likely involved in the PSII response to the cold treatment. The gene encodes the PSII associated protein PSB27 which has already been implicated in the adaptation to fluctuating light. 相似文献
57.
Suping Zhang Futian Tang Yuhong Yang Meili Lu Aina Luan Jing Zhang Juan Yang Hongxin Wang 《PloS one》2015,10(3)
We previously reported that Astragaloside IV (ASIV), a major active constituent of Astragalus membranaceus (Fisch) Bge protects against cardiac hypertrophy in rats induced by isoproterenol (Iso), however the mechanism underlying the protection remains unknown. Dysfunction of cardiac energy biosynthesis contributes to the hypertrophy and Nuclear Factor κB (NF-κB)/Peroxisome Proliferator-Activated Receptor-γ Coactivator 1α (PGC-1α) signaling gets involved in the dysfunction. The present study was designed to investigate the mechanism by which ASIV improves the cardiac hypertrophy with focuses on the NF-κB/PGC-1α signaling mediated energy biosynthesis. Sprague-Dawley (SD) rats or Neonatal Rat Ventricular Myocytes (NRVMs) were treated with Iso alone or in combination with ASIV. The results showed that combination with ASIV significantly attenuated the pathological changes, reduced the ratios of heart weight/body weight and Left ventricular weight/body weight, improved the cardiac hemodynamics, down-regulated mRNA expression of Atrial Natriuretic Peptide (ANP) and Brain Natriuretic Peptide (BNP), increased the ratio of ATP/AMP, and decreased the content of Free Fat Acid (FFA) in heart tissue of rats compared with Iso alone. In addition, pretreatment with ASIV significantly decreased the surface area and protein content, down-regulated mRNA expression of ANP and BNP, increased the ratio of ATP/AMP, and decreased the content of FFA in NRVMs compared with Iso alone. Furthermore, ASIV increased the protein expression of ATP5D, subunit of ATP synthase and PGC-1α, inhibited translocation of p65, subunit of NF-κB into nuclear fraction in both rats and NRVMs compared with Iso alone. Parthenolide (Par), the specific inhibitor of p65, exerted similar effects as ASIV in NRVMs. Knockdown of p65 with siRNA decreased the surface areas and increased PGC-1α expression of NRVMs compared with Iso alone. The results suggested that ASIV protects against Iso-induced cardiac hypertrophy through regulating NF-κB/PGC-1α signaling mediated energy biosynthesis. 相似文献
58.
Pilar Fuster-Parra Miquel Bennasar-Veny Pedro Tauler Aina Ya?ez Angel A. López-González Antoni Aguiló 《PloS one》2015,10(3)
Background
Because the accurate measure of body fat (BF) is difficult, several prediction equations have been proposed. The aim of this study was to compare different multiple regression models to predict BF, including the recently reported CUN-BAE equation.Methods
Multi regression models using body mass index (BMI) and body adiposity index (BAI) as predictors of BF will be compared. These models will be also compared with the CUN-BAE equation. For all the analysis a sample including all the participants and another one including only the overweight and obese subjects will be considered. The BF reference measure was made using Bioelectrical Impedance Analysis.Results
The simplest models including only BMI or BAI as independent variables showed that BAI is a better predictor of BF. However, adding the variable sex to both models made BMI a better predictor than the BAI. For both the whole group of participants and the group of overweight and obese participants, using simple models (BMI, age and sex as variables) allowed obtaining similar correlations with BF as when the more complex CUN-BAE was used (ρ = 0:87 vs. ρ = 0:86 for the whole sample and ρ = 0:88 vs. ρ = 0:89 for overweight and obese subjects, being the second value the one for CUN-BAE).Conclusions
There are simpler models than CUN-BAE equation that fits BF as well as CUN-BAE does. Therefore, it could be considered that CUN-BAE overfits. Using a simple linear regression model, the BAI, as the only variable, predicts BF better than BMI. However, when the sex variable is introduced, BMI becomes the indicator of choice to predict BF. 相似文献59.
Aina Ramsay Ophélie Fliniaux Jingjing Fang Roland Molinie Albrecht Roscher Eric Grand Xavier Guillot José Kovensky Marc-André Fliniaux Bernd Schneider François Mesnard 《Metabolomics : Official journal of the Metabolomic Society》2014,10(6):1258-1267
Flaxseed is an important source of lignans and ω-3 fatty acids, compounds which present interest in human health with many applications in food industry. It is therefore necessary to precisely know the metabolite content in flaxseed. A metabolomic approach using NMR was developed to achieve this goal. Due to particular characteristics of flaxseed (high level in oil, high amount in mucilage, and integration of the phenolics into a macromolecule), the extraction procedure had first to be optimized using an experimental design, based on the extraction time, in a water bath or an ultrasound bath, alkaline treatment, defatting, and centrifugation temperature. This methodology was then applied to several flaxseed varieties classified in function of their content in ω-3 fatty acid. The main differences in semi-polar metabolites between these varieties concern compounds of the phenylpropanoid pathway. Hydroxycinnamic acid glucoside and lignan content increase when ω-3 fatty acid content decrease whereas flavonoid content increase in the same way of ω-3 fatty acids. 相似文献
60.
Nobuaki Niwa Miguel Vazquez Archdale Takashi Matsuoka Aina Kawamoto Haruka Nishiyama 《Central European Journal of Biology》2014,9(1):80-85
A study was performed on the microhabitat distribution and some aspects of behaviour of the ectosymbiotic branchiobdellidan Holtodrilus truncatus (Annelida, Clitellata) found on the freshwater shrimp that inhabit the Sugo River, Hyogo Prefecture, western Japan. Observations on shrimp that were collected from the Sugo River (2003 to 2011) confirmed that the host shrimp is Neocaridina spp. (Atyidae). The attachment location on the host shrimp was predominately between the 1st pleopod and the 5th pereopod (55.3%). The reproductive method of H. truncatus is hemaphroditism. The cocoon was found only inside the carapace of the host shrimp. The cocoon was transparent and contained a maximum of 14 juvenile worms (developing embryos). When hatching approached, H. truncatus’s worms became elongated and slender, and only one worm hatched out at a time. When Holtodrilus truncatus was removed from its host and was maintained in river water without any food, it survived for a maximum of 46 days. In a host exchange experiment, where we provided several other freshwater shrimp species, Palaemonidae fed on H. truncatus. Moreover, Palaemon paucidens and Macrobrachium nipponense from Lake Biwa also preyed upon H. truncatus. The possible symbiotic relationship between H. truncatus and Neocaridina spp. (family Atyidae) is further discussed. 相似文献