Selection of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> TN627 as a new probiotic candidate based on <Emphasis Type="Italic">in vitro</Emphasis> functional properties

Nine lactobacilli previously selected for high antagonism against food borne bacterial pathogens were identified via 16S rRNA gene sequencing and screened for probiotic potential for use in poultry production. The lactobacilli were subjected to a subtractive in vitro analysis system using a certified probiotic as reference. This allowed for selection of a milk-derived Lactobacillus plantarum strain, termed TN627. This organic acid-producing bacterium was free of harmful enzymatic activity and sensitive to several antibiotics. It also showed good growth at pH 4 and in the presence of bile. L. plantarum TN627 also exhibited high efficacy of adhesion to chicken enterocytes, which correlated with detecting genes encoding the mucusbinding, adhesion-promoting proteins (Mub and MapA) and the adhesion-like factor EF-Tu, commonly involved in adherence of lactobacilli to mucosal surfaces. Taken together, our findings suggest that TN627 is a promising probiotic candidate with high potential for application as a supplement in the animal feed industry.     

Structural insight into a novel human CCR5-V130I variant associated with resistance to HIV-1 infection

We report the identification of a novel CC chemokine receptor 5 (CCR5) variant that seems associated with resistance to HIV-1 infection. The V130I mutation of the CCR5 receptor is located in the intracellular loop ICL2 known as DRY box and described in the literature as a nonsynonymous mutation present in nonhuman primates group. Extensive molecular modeling and dynamics simulations were performed to elucidate the mechanism by which the V130I mutation may induce conformational change of the CCR5 folding protein and prevent the interaction with the β-arrestin protein. Our study provides new mechanistic insight into how a specific mutation in the regulatory domain of CCR5 might alter the structural folding of the DRY box and the possible ICL2 loop binding with the β-arrestin protein, as described in our previous computational study. The results from our large-scale simulations complement recent experimental results and clinical features and offer useful insights into the mechanism behind CCR5 protein folding and signal transduction. In order for HIV, the entry of the virus to the cells must fuse with the CCR5 receptor that sits on the surface of T-helper immune cells. The described V130I mutation in the gene encoding the CCR5 protein may results in a defective CCR5-Arrestin binding complex that blocks entry of the virus.     

Understanding the domino retro [3+2] cycloaddition/cyclization reaction of bicyclic isoxazolidines in the synthesis of spirocyclic alkaloids. A DFT study

Journal of Molecular Modeling - Hyperjovinol-A ((2-methyl-1-(2,4,6-trihydroxy-3-(3-hydroxy-3,7-dimethyloct-6-enyl)phen yl)propan-1-one) is an acylated phloroglucinol isolated from Hypericum Jovis...     

Synthesis and anti-HSV activity of new N1-acyclic C4 and C6-disubstituted pyrazolo[3,4-d]pyrimidine nucleosides

Several N(1)-(2-hydroxyethoxy)methyl, (4-hydroxybutyl) and (2,3-dihydroxy-1-propoxy)methyl-C(4),C(6)-disubstituted-1H-pyrozolo[3,4-d]pyrimidines were synthesized. Some of them were evaluated against herpes simplex virus 1 and 2 replications in E(6)SM cells.     

Effect of time of day on the offensive capability and aerobic performance in football game

The purpose of this study was to examine the time-of-day effects on the offensive capability and aerobic performance in football game in young subjects. In a randomized order, participants realized the Yo–Yo intermittent recovery test in two test sessions and a football game situations (two 15-min games), interspersed by a verbalization sequence (3 min) at 08:00 and 17:00 h on separate days. A recovery period of 24 h was permitted between two consecutive test sessions. The results revealed diurnal variations on the maximal aerobic velocity during the Yo–Yo test (MAV) and the oral temperature with higher values in the afternoon than morning (p < 0.05). Concerning offensive capability, the numbers of scored goals were significantly higher at 17:00 h in comparison with 08:00 h (p < 0.05). However, there was no significant difference between 08:00 and 17:00 h for the kicked balls (shooting parameter). In conclusion, our findings suggest that performance was improved in the evening and the parameters (shooting and Scored goals) can be used as a model to describe the offensive capacity in football game depending on the time of day.     

Purification and characterization of two extracellular peroxidases from Streptomyces sp. strain AM2, a decolorizing actinomycetes responsible for the biodegradation of natural humic acids

Two extracellular humic acids peroxidases called HaP1 and HaP2 were isolated from the Streptomyces sp. strain AM2 and, based on MALDI-TOF MS analysis. The purified enzymes were determined as monomers with molecular masses of 40,351.11 and 25,175.19 Da, respectively. The N-terminal amino acid sequences of HaP1 and HaP2 were identified, and their optimum pH values were determined as 6 and 7.5, respectively. Standard 2,4-dichlorophenol (2,4-DCP) assays showed that both enzymes had maximal activity at 55 °C. HaP2 was stable at 55 °C for more than 24 h and had a half-life of 90 min at 65 °C. Although the catalytic properties of HaP1 and HaP2 were nearly identical, their stabilities and Reinheitzahl (RZ) values were substantially different. Both peroxidases were found to be heme proteins that catalyzed the oxidation of a wide range of substrates in the presence of hydrogen peroxide (H₂O₂), with HaP2 exhibiting a broader range of substrate specificity. The characterization of peroxidase activity revealed activity against humic acids, guiacol, 2,4-DCP, l-3,4-dihydroxyphenylalanine, and 2,4,5-trichlorophenol as well as other chlorophenols in the presence of H₂O₂. However, the inhibition of peroxidase activity by the addition of potassium cyanide and sodium azide also indicated the presence of heme components in the tertiary structure of these enzymes.     

Symbiotic characterization and diversity of rhizobia associated with native and introduced acacias in arid and semi-arid regions in Algeria

The diversity of rhizobia associated with introduced and native Acacia species in Algeria was investigated from soil samples collected across seven districts distributed in arid and semi-arid zones. The in vitro tolerances of rhizobial strains to NaCl and high temperature in pure culture varied greatly regardless of their geographical and host plant origins but were not correlated with the corresponding edaphoclimatic characteristics of the sampling sites, as clearly demonstrated by principal component analysis. Based on 16S rRNA gene sequence comparisons, the 48 new strains isolated were ranked into 10 phylogenetic groups representing five bacterial genera, namely, Ensifer, Mesorhizobium, Rhizobium, Bradyrhizobium, and Ochrobactrum. Acacia saligna, an introduced species, appeared as the most promiscuous host because it was efficiently nodulated with the widest diversity of rhizobia taxa including both fast-growing ones, Rhizobium, Ensifer, and Mesorhizobium, and slow-growing Bradyrhizobium. The five other Acacia species studied were associated with fast-growing bacterial taxa exclusively. No difference in efficiency was found between bacterial taxa isolated from a given Acacia species. The tolerances of strains to salinity and temperature remains to be tested in symbiosis with their host plants to select the most adapted Acacia sp.-LNB taxa associations for further revegetation programs.     

Hormonal regulation of two urea-cycle enzymes in cultured foetal hepatocytes.

Foetal-rat hepatocytes were cultured in primary monolayer culture, and activity changes of argininosuccinate synthetase (ASS, EC 6.3.4.5) and argininosuccinase (ASL, EC 4.3.2.1) were followed under defined hormone conditions. In hormone-free medium, cultured cells maintained the enzyme activities at values equal to those of freshly isolated cells for at least 3 days. Continuous addition of dexamethasone produced the development of the two enzyme activities, but only after the first 20h of culture. Under these conditions, urea production by the foetal hepatocytes was concomitantly increased in the culture medium. Pretreatment with dexamethasone for 20h was sufficient to produce the development of ASL activity within the 2 following days. Introduced alone, glucagon induced an increase of ASL activity, but did not affect the ASS activity. The most powerful stimulation of ASS and ASL could be observed in cultured hepatocytes if glucagon and dexamethasone were added simultaneously or sequentially. These results indicated that the development of the receptor complex for the induction of urea-cycle enzymes appears early before birth and established that glucocorticoids amplify the glucagon stimulation of these enzyme activities during foetal life.     

Precocious induction of arginase in primary cultures of fetal rat hepatocytes

Summary Fetal rat hepatocytes were isolated and cultured in primary culture to investigate activity changes of arginase under defined conditions. In hormone-free medium, cultured cells maintained the enzyme activity at levels equal to that of freshly isolated cells for at least 4 d. Arginase activity could be induced by dexamethasone in hepatocytes isolated from 16.5-d-old fetuses although cells were competent to respond to glucagon only at the stage of 18.5 d. The combination of the two hormones induced greater levels of arginase activity than the individual compounds. These findings indicate that glucocorticoid and glucagon receptors appear early and sequentially before birth and reveal that cultured fetal hepatocytes provide a suitable system for the investigation of the role of hormones in the initiation of enzyme synthesis. This work was supported by the Institut National Scientifique et de la Recherche Médicale through Grant 85.80.117.