Characterization of Serracin P, a Phage-Tail-Like Bacteriocin, and Its Activity against Erwinia amylovora, the Fire Blight Pathogen

Serratia plymithicum J7 culture supernatant displayed activity against many pathogenic strains of Erwinia amylovora, the causal agent of the most serious bacterial disease of apple and pear trees, fire blight, and against Klebsiella pneumoniae, Serratia liquefaciens, Serratia marcescens, and Pseudomonas fluorescens. This activity increased significantly upon induction with mitomycin C. A phage-tail-like bacteriocin, named serracin P, was purified from an induced culture supernatant of S. plymithicum J7. It was found to be the only compound involved in the antibacterial activity against sensitive strains. The N-terminal amino acid sequence analysis of the two major subunits (23 and 43 kDa) of serracin P revealed high homology with the Fels-2 prophage of Salmonella enterica, the coliphages P2 and 168, the CTX prophage of Pseudomonas aeruginosa, and a prophage of Yersinia pestis. This strongly suggests a common ancestry for serracin P and these bacteriophages.     

L-nucleotides and 8-methylguanine of d(C1m8G2C3G4C5LG6LC7G8C9G10)2 act cooperatively to promote a left-handed helix under physiological salt conditions

The structure and thermal stability of a hetero chiral decaoligodeoxyribonucleotide duplex d(C1m8 G2C3G4C5LG6LC7G8C9G10)d(C11m8G12C13G14C15LG16LC17G18C19G20) (O1) with two contiguous pairs of enantiomeric 2'-deoxy-L-ribonucleotides (C5LG6L/C15LG16L) at its centre and an 8-methylguanine at position 2/12 was analysed by circular dichroism, NMR and molecular modelling. O1 resolves in a left-handed helical structure already at low salt concentration (0.1 M NaCl). The central L2-sugar portion assumes a B* left-handed conformation (mirror-image of right-handed B-DNA) while its flanking D4-sugar portions adopt the known Z left-handed conformation. The resulting Z4-B2*-Z4 structure (left-handed helix) is the reverse of that of B4-Z2*-B4 (right-handed helix) displayed by the nearly related decaoligodeoxyribonucleotide d(mC1G2mC3G4C5L G6LmC7G8mC9G10)2, at the same low salt concentration (0.1 M NaCl). In the same experimental conditions, d(C1m8G2C3G4C5G6C7G8C9G10)2 (O2), the stereoregular version of O1, resolves into a right-handed B-DNA helix. Thus, both the 8-methylguanine and the enantiomeric step CLpGL at the centre of the molecule are needed to induce left-handed helicity. Remarkably, in the various heterochiral decaoligodeoxyribonucleotides so far analysed by us, when the central CLpGL adopts the B* (respectively Z*) conformation, then the adjacent steps automatically resolves in the Z (respectively B) conformation. This allows a good optimisation of the base-base stackings and base-sugar van der Waals interactions at the ZB*/B*Z (respectively BZ*/Z*B) junctions so that the Z4-B2*-Z4 (respectively B4-Z2*-B4) helix displays a Tm (approximately 65 degrees C) that is only 5 degrees C lower than the one of its homochiral counterpart. Here we anticipate that a large variety of DNA helices can be generated at low salt concentration by manipulating internal factors such as sugar configuration, duplex length, nucleotide composition and base methylation. These helices can constitute powerful tools for structural and biological investigations, especially as they can be used in physiological conditions.     

Genetic diversity in natural Cupressus sempervirens L. populations in Turkey

Nine polymorphic out of 13 isoenzymes (Gdh-A, Lap-A, Mdh-B, Mdh-C, Ndh-A, 6Pgd-B, Pgi-B, Pgm-A and Pgm-B) were used to assess genetic diversity in seven natural Cupressus sempervirens populations in South-western Anatolia. Except for Pgi-B, all loci were in Hardy–Weinberg equilibrium. A high level of genetic diversity was observed within populations. The mean number of alleles was 2.3±0.08, the effective number of alleles was 1.53±0.10, the percentage of polymorphic loci was 82.6±8.7%, expected heterozygosity was 0.350±0.039, observed heterozygosity was 0.326±0.039, and the fixation index was 0.049. Interpopulation differentiation was moderate, with differentiation indices of G_ST=0.073 and δ=0.104. A UPGMA tree and differentiation (D_j) showed that Kumluca, Kemer and Kas were the most differentiated populations. Pgm-B was one of the loci contributing most to interpopulation differentiation (G_ST=0.119; D_i=0.201), clearly distinguishing Eastern populations, as indicated by a highly significant correlation coefficient between D_j and longitude (R²=0.88^**). No other significant correlation was found between genetic measures and geographical traits for the Turkish cypress populations. A metanalysis of these and other cypress populations from Crete and the Aegean islands, that had been characterised previously using the same isoenzymes, showed no significant relationship between altitude and genetic measures (within-population differentiation or δ_T, observed heterozygosity, fixation index and D_j). Observed heterozygosity and latitude were negatively correlated. Longitude was found to be correlated with heterozygosity, fixation index and differentiation. Genetic and geographic distances were positively correlated over loci. Deviations from selective neutrality by Ewens–Watterson test were observed for Pgm-B, Ndh-A and 6Pgd-B.     

Enhanced catecholamine transporter binding in the locus coeruleus of patients with early Parkinson disease

Background  

Studies in animals suggest that the noradrenergic system arising from the locus coeruleus (LC) and dopaminergic pathways mutually influence each other. Little is known however, about the functional state of the LC in patients with Parkinson disease (PD).     

Effects of Acute or Chronic Ethanol Exposure during Adolescence on Behavioral Inhibition and Efficiency in a Modified Water Maze Task

Ethanol is well known to adversely affect frontal executive functioning, which continues to develop throughout adolescence and into young adulthood. This is also a developmental window in which ethanol is misused by a significant number of adolescents. We examined the effects of acute and chronic ethanol exposure during adolescence on behavioral inhibition and efficiency using a modified water maze task. During acquisition, rats were trained to find a stable visible platform onto which they could escape. During the test phase, the stable platform was converted to a visible floating platform (providing no escape) and a new hidden platform was added in the opposite quadrant. The hidden platform was the only means of escape during the test phase. In experiment 1, adolescent animals received ethanol (1.0g/kg) 30min before each session during the test phase. In experiment 2, adolescent animals received chronic intermittent ethanol (5.0g/kg) for 16 days (PND30 To PND46) prior to any training in the maze. At PND72, training was initiated in the same modified water maze task. Results from experiment 1 indicated that acute ethanol promoted behavioral disinhibition and inefficiency. Experiment 2 showed that chronic intermittent ethanol during adolescence appeared to have no lasting effect on behavioral disinhibition or new spatial learning during adulthood. However, chronic ethanol did promote behavioral inefficiency. In summary, results indicate that ethanol-induced promotion of perseverative behavior may contribute to the many adverse behavioral sequelae of alcohol intoxication in adolescents and young adults. Moreover, the long-term effect of adolescent chronic ethanol exposure on behavioral efficiency is similar to that observed after chronic exposure in humans.     

Effects of Externally Applied Pressure on the Haemodynamics of the Lower Limb

The effects of externally applied pressure of 5-150 mm Hg on the haemodynamics of the leg of dog and man were investigated. The criteria used for the assessments included femoral arterial and venous blood flow as well as vascular hydraulic conductance. The results indicated that external pressure of 5 mm Hg results in a very small non-significant increase in the femoral arterial and venous flow. Higher external pressure of 15 mm Hg or more significantly reduces the femoral arterial and venous flows as well as the vascular conductance. It therefore seems that compression produced by bandaging in horizontal supine subjects has little or no haemodynamic value and may prove to be harmful unless carefully controlled.     

Alterations of hepatocyte function with free radical generators and reparation or prevention with coffee polyphenols

Liver diseases are linked in the majority of cases to oxidative stress that antioxidants could neutralize with reducing liver injury. Chlorogenic acid, a coffee polyphenol, possesses antioxidant prosperities. The aim of this study was to evaluate in vitro preventive and corrective effects of cholorogenic acid in hepatocyte toxicity induced by free radicals. Hepatocytes were isolated from adult male Wistar rats. To determine corrective effects and reparation, cells were first exposed to two free radical generators (hydrogen peroxide/iron sulfate for hydroxyl radical formation, and phenazine methosulfate/nicotinamide adenine dinucleotide for superoxide anion formation) for 12H and thereafter treated by chlorogenic acid (1 and 10?μM final concentration) for another 12H. To show preventive effects, cells were pretreated by chlorogenic acid and thereafter exposed to free radical generators. Hepatocyte proliferation, glucose uptake, ATP contents, membrane fluidity and integrity, and intracellular redox status were investigated after 24H culture. The results showed that chlorogenic acid reversed the decrease in cell proliferation, glucose uptake and ATP levels, the increased LDH release and the reduced membrane fluidity and restored the oxidant/antioxidant status under oxidative stress. When pre-treated with chlorogenic acid, hepatocytes became very resistant to oxidative conditions and cellular homeostasis was maintained. In conclusion, chlorogenic acid displayed not only corrective but also preventive effects in hepatocytes exposed to oxidative stress and could be beneficial in patients with or at risk of liver diseases.