Pilus Gene Pool Variation and the Virulence of Corynebacterium diphtheriae Clinical Isolates during Infection of a Nematode

Toxigenic Corynebacterium diphtheriae strains cause diphtheria in humans. The toxigenic C. diphtheriae isolate NCTC13129 produces three distinct heterotrimeric pili that contain SpaA, SpaD, and SpaH, making up the shaft structure. The SpaA pili are known to mediate bacterial adherence to pharyngeal epithelial cells. However, to date little is known about the expression of different pili in various clinical isolates and their importance in bacterial pathogenesis. Here, we characterized a large collection of C. diphtheriae clinical isolates for their pilin gene pool by PCR and for the expression of the respective pilins by immunoblotting with antibodies against Spa pilins. Consistent with the role of a virulence factor, the SpaA-type pili were found to be prevalent among the isolates, and most significantly, corynebacterial adherence to pharyngeal epithelial cells was strictly correlated with isolates that were positive for the SpaA pili. By comparison, the isolates were heterogeneous for the presence of SpaD- and SpaH-type pili. Importantly, using Caenorhabditis elegans as a model host for infection, we show here that strain NCTC13129 rapidly killed the nematodes, the phenotype similar to isolates that were positive for toxin and all pilus types. In contrast, isogenic mutants of NCTC13129 lacking SpaA-type pili or devoid of toxin and SpaA pili exhibited delayed killing of nematodes with similar kinetics. Consistently, nontoxigenic or toxigenic isolates that lack one, two, or all three pilus types were also attenuated in virulence. This work signifies the important role of pili in corynebacterial pathogenesis and provides a simple host model to identify additional virulence factors.     

Determination of Physiological Indices and Some Antioxidant Enzymes of Chard Exposed to Nitric Oxide under Drought Stress

Russian Journal of Plant Physiology - This research was carried out to determine effectiveness of nitric oxide (NO) on some physiological and biochemical reactions, and water use efficiency (WUE)...     

Combination Therapy of Gabapentin and N-Acetylcysteine Against Posttraumatic Epilepsy in Rats

Traumatic brain injury (TBI) is a major public health problem worldwide that is associated with increased mortality and morbidity. Posttraumatic epilepsy (PTE) is one of the sequelae of TBI. The aim of this study was to investigate the role of N-acetylcysteine (NAC) as an adjuvant on the efficacy of levetiracetam (LEV) and gabapentin (GBP) in PTE model encouraged by pentylenetetrazol (PTZ) after mild-TBI in male Sprague–Dawley rats. Mild-TBI was performed by the weight-drop method in male Sprague–Dawley rats. PTE model was developed by injecting PTZ (30+15+15 mg/kg, 30 min intervals, i.p.) 7 days after head trauma. After the development of posttraumatic seizures, the rats were treated with NAC (100 mg/kg), LEV (50 mg/kg), GBP (100 mg/kg), NAC+LEV and NAC+GBP intraperitoneally for 14 days. Seizures related to PTE were scored by video-EEG recording. Motor performance of the animals was also evaluated in the rotarod test. 50 mg/kg LEV and 100 mg/kg GBP reduced seizures related to PTE. LEV alone (p?=?0.009), but the administration of GBP+NAC (p?=?0.015) was more effective on PTE-related seizure control. However, GBP+NAC application adversely affected the fall latency in the rotarod test. In terms of trauma-related seizure control, there was no statistically significant difference between the use of prophylactic LEV and symptomatic LEV. LEV alone or the combination of GBP with NAC provides more effective seizure control in the PTE facilitated by PTZ. On the other hand, the use of prophylactic LEV did not have any extra effect on posttraumatic seizure development and control.

     

A comprehensive and comparative phenotypic analysis of the collaborative founder strains identifies new and known phenotypes

Mammalian Genome - The collaborative cross (CC) is a large panel of mouse-inbred lines derived from eight founder strains (NOD/ShiLtJ, NZO/HILtJ, A/J, C57BL/6J, 129S1/SvImJ, CAST/EiJ, PWK/PhJ, and...     

Covalent immobilization of catalase onto spacer-arm attached modified florisil: characterization and application to batch and plug-flow type reactor systems

Catalase was covalently immobilized onto florisil via glutaraldehyde (GA) and glutaraldehyde+6-amino hexanoic acid (6-AHA) (as a spacer arm). Immobilizations of catalase onto modified supports were optimized to improve the efficiency of the overall immobilization procedures. The V(max) values of catalase immobilized via glutaraldehyde (CIG) and catalase immobilized via glutaraldehyde+6-amino hexanoic acid (CIG-6-AHA) were about 0.6 and 3.4% of free catalase, respectively. The usage of 6-AHA as a spacer arm caused about 40 folds increase in catalytic efficiency of CIG-6-AHA (8.3 × 10? M?1 s?1) as compared to that of CIG (2.1 × 10? M?1 s?1). CIG and CIG-6-AHA retained 67 and 35% of their initial activities at 5 °C and 71 and 18% of their initial activities, respectively at room temperature at the end of 6 days. Operational stabilities of CIG and CIG-6-AHA were investigated in batch and plug-flow type reactors. The highest total amount of decomposed hydrogen peroxide (TAD-H?O?) was determined as 219.5 μmol for CIG-6-AHA in plug-flow type reactor.     

Mbd3/NURD complex regulates expression of 5-hydroxymethylcytosine marked genes in embryonic stem cells

Numerous chromatin regulators are required for embryonic stem (ES) cell self-renewal and pluripotency, but few have been studied in detail. Here, we examine the roles of several chromatin regulators whose loss affects the pluripotent state of ES cells. We find that Mbd3 and Brg1 antagonistically regulate a common set of genes by regulating promoter nucleosome occupancy. Furthermore, both Mbd3 and Brg1 play key roles in the biology of 5-hydroxymethylcytosine (5hmC): Mbd3 colocalizes with Tet1 and 5hmC in vivo, Mbd3 knockdown preferentially affects expression of 5hmC-marked genes, Mbd3 localization is Tet1-dependent, and Mbd3 preferentially binds to 5hmC relative to 5-methylcytosine in vitro. Finally, both Mbd3 and Brg1 are themselves required for normal levels of 5hmC in vivo. Together, our results identify an effector for 5hmC, and reveal that control of gene expression by antagonistic chromatin regulators is a surprisingly common regulatory strategy in ES cells.     

Production of recombinant bacteriocin divercin V41 by high cell density <Emphasis Type="Italic">Escherichia coli</Emphasis> batch and fed-batch cultures

To increase the yield of heterologous production of the class II bacteriocin DvnRV41 with Escherichia coli Origami (DE3) (pLysS/pCR03), induction of bacteriocin gene expression was optimized by varying the inducer isopropyl beta-D-thiogalactopyranoside (IPTG) concentration (0-2 mM), and controlled batch and fed-batch cultures were tested on a 2-L scale. A concentration of 0.5 mM IPTG was found to be optimal for cell growth and bacteriocin production. Shake flask cultivation of E. coli Origami (DE3) (pLysS/pCR03) gave biomass and bacteriocin yields of 1.54 +/- 0.06 g cdw/l and 18 +/- 1 mg DvnRV41/l, respectively. Biomass (2.70 +/- 0.06 and 6.8 +/- 0.6 g cdw/l, respectively) and bacteriocin yields (30 and 74 mg DvnRV41 per liter, respectively) were both increased with batch and fed-batch compared to shake flask cultures. Bacteriocin yields reported in this study are among the highest published for other heterologous expression systems in shake flasks.     

N-acetyltransferase 2 polymorphism in patients with diabetes mellitus

The arylamine N-acetyltransferases (NATs) are a unique family of enzymes that catalyse the transfer of an acetyl group from acetyl-CoA to the terminal nitrogen of hydrazine and arylamine drugs and carcinogens. Human arylamine NATs are known to exist as two isoenzymes, NAT1 and NAT2. The objective of this study was to identify whether the genetic polymorphism of NAT2 plays a role in susceptibility to Diabetes Mellitus (DM). Ninety-seven patients with DM and 104 healthy controls were enrolled in the study. NAT2*5A, NAT2*6A, NAT2*7A/B and NAT2*14A polymorphisms were detected by using real time PCR with LightCycler (Roche Diagnostics GmbH, Mannheim, Germany). According to our data, the NAT2*5A and NAT2*6A mutant genotypes and NAT2*14A heterozygous genotype were associated with an increased risk of development of DM (OR = 47.06; 95%CI: 10.55-209.77 for NAT 2*5A, OR = 18.48; 95%CI: 3.83-89.11 for NAT2*6A and OR = 18.22; 95%CI: 6.29-52.76 for NAT2*14A). However, the NAT2*7A/B gene polymorphism carried no increased risk for developing DM disease. After grouping according to phenotypes as either slow or fast acetylators, NAT2*6A slow acetylator was found to be a significant risk factor for DM (OR = 6.09; 95%CI: 1.99-18.6, p = 0.02). The results indicate that NAT2 slow acetylator genotypes may be an important genetic determinant for DM in the Turkish population.     

Mitigation of salinity stress in cucumber seedlings by exogenous hydrogen sulfide

Journal of Plant Research - This research hypothesized that tolerance of cucumber seedlings to salinity stress could be increased by hydrogen sulfide (H2S) treatments. In pot experiments, the...