Divergicin M35-Chitosan Film: Development and Characterization

Chitosan films loaded with bacteriocin were examined by FTIR spectroscopy, tested for color, puncture strength, water vapor permeability, and as antimicrobials of Listeria innocua HPB13. Divergicin M35, a bacteriocin produced by Carnobacterium divergens, was incorporated into films made with chitosan of molecular mass 2 kDa, 20 kDa, or 100 kDa and de-acetylated either 87% or 95%. Only 100 kDa chitosan yielded films that could be peeled and handled easily. The higher degree of de-acetylation increased the total color factor (ΔE) of bacteriocin-loaded films, their permeability, and puncture strength. Incorporation of divergicin M35 into the films increased amide I peak intensity but otherwise did not induce significant structural change. The FTIR spectra of divergicin M35 shed from the films did not differ from those of the original free bacteriocin, except in overall peak intensity. The release of active divergicin M35 from the film was faster into the buffer than into tryptic soy broth and peaked at 10–12 h in both cases. Chitosan 95% de-acetylated and loaded with divergicin M35 was the most active, producing a six-log drop in Listeria innocua HPB13 viable count within 24 h. These results suggest that the biocompatible and biodegradable films developed here have the potential for application as antimicrobials of Listeria spp. in foods, especially ready-to-eat, minimally processed products.

     

Depletion of neutrophils in IL-10(-/-) mice delays clearance of gastric Helicobacter infection and decreases the Th1 immune response to Helicobacter

Gastric infection with Helicobacter induces a lymphocyte-rich mucosal inflammation that contains a minor population of neutrophilic granulocytes. The function of neutrophils in the local immune response to gastric Helicobacter infection remains unknown. To investigate this issue, we conducted experiments in neutrophil-depleted control wild-type (wt) and IL-10(-/-) mice infected with Helicobacter felis by gastric lavage. Infection of wt mice elicited a mild, focal gastritis and a Helicobacter-specific Th1 immune response. In wt mice Helicobacter colonization of the stomach was persistent and progressively increased during the 29 days of observation. Infection of IL-10(-/-) mice with H. felis elicited a severe chronic gastritis and a greatly enhanced Helicobacter-specific Th1 immune response, as compared with wt mice. After initial colonization, the IL-0(-/-) mice completely cleared Helicobacter from the stomach by day 8. The gastric inflammation in wt and IL-10(-/-) mice contained modest numbers of neutrophils. The intensity of gastric inflammation and the extent of Helicobacter colonization were similar in control and in neutrophil-depleted wt mice. In contrast, neutrophil depletion of Helicobacter-infected IL-10(-/-) mice decreased the severity of gastritis, modulated the Helicobacter-specific Th1 immune response, and delayed the clearance of bacteria from the stomach. These studies identify a role for neutrophils in the local and systemic immune response to gastric Helicobacter in IL-10(-/-) mice.     

Growth of <Emphasis Type="Italic">Streptomyces</Emphasis> spp. from hydrocarbon-polluted soil on diesel and their analysis for the presence of alkane hydroxylase gene (<Emphasis Type="Italic">alkB</Emphasis>) by PCR

The investigation aimed to examine the Streptomyces flora of hydrocarbon-contaminated soil and study their capability to grow on diesel fuel as a sole carbon source and their analysis for the presence of the alkane hydroxylase gene (alkB) by PCR. A total of 16 Streptomyces isolates were recovered from hydrocarbon-contaminated soil samples on starch casein nitrate agar medium with the ability of 3 isolates to grow on diesel as evaluated by agar plate diffusion method, enzymatic assay and dry weight measurements. PCR analysis of the isolates for the presence of the alkB gene showed two groups with different band size products; group 1 (G1) (316–334 bp) and group 2 (G2) (460–550 bp). Three isolates (SF.1Ac, SF.2Ba, and SF.3Ad) grew around diesel-containing wells and contained the alkB gene with size band ranged between 320 and 550 bp. However; one isolate (SF.1Aa) did not show any PCR product although it was able to grow on diesel. This implies that the alkB gene is not the only gene that is responsible for the degradation of alkanes. Further, the variation in the G2 fragment size probably indicates different related genes that might be involved in alkane degradation rather than a single gene.     

The interplay between RPGR,PDEδ and Arl2/3 regulate the ciliary targeting of farnesylated cargo

Defects in primary cilia result in human diseases known as ciliopathies. The retinitis pigmentosa GTPase regulator (RPGR), mutated in the most severe form of the eye disease, is located at the transition zone of the ciliary organelle. The RPGR‐interacting partner PDEδ is involved in trafficking of farnesylated ciliary cargo, but the significance of this interaction is unknown. The crystal structure of the propeller domain of RPGR shows the location of patient mutations and how they perturb the structure. The RPGR·PDEδ complex structure shows PDEδ on a highly conserved surface patch of RPGR. Biochemical experiments and structural considerations show that RPGR can bind with high affinity to cargo‐loaded PDEδ and exposes the Arl2/Arl3‐binding site on PDEδ. On the basis of these results, we propose a model where RPGR is acting as a scaffold protein recruiting cargo‐loaded PDEδ and Arl3 to release lipidated cargo into cilia.     

Efficacy of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against Thaumetopoea pityocampa Shiff. (Lepidoptera: Thaumatopoeidae)

Abstract

In this study, Metarhizium anisopliae TR 106 and Beauveria bassiana TR 217 was tested against fourth instar larvae of Thaumetopoea pityocampa. The LT₅₀ and LT₉₀ of 1?×?10⁶ concentration of M. anisopliae against T. pityocampa were 3.60 and 4.11 for direct application, while these were 2.87 and 3.60?days, respectively in leaves application. The LT₅₀ and LT₉₀ of the 1?×?10⁸ concentration of the same isolate were 2.50 and 2.95?days for direct application, and 2.98 and 3.74?days for leaves application. The LT₅₀ of insect and leaves application for 1?×?10⁶ of B. bassiana were 3.75 and 3.49?days, respectively. The LT₉₀ of same concentration for insect application was 4.48?days, while LT₉₀ for leaves application was 4.63?days. Similarly, LT₅₀ of insect and leaves application for 1?×?10⁸ of B. bassiana were 3.03 and 3.31?days, while LT₉₀ were 3.68 and 4.29?days, respectively. Approximate 100% mycosis was observed in all treatments.     

Zinc-dependent changes in ESR signals, NADPH oxidase and plasma membrane permeability in cotton roots

The effect of Zn²⁺ on the plasma membrane permeability and superoxide radical (O₂^-) formation in roots was studied with cotton ( Gossypium hirsutum L. cv. Delta-pine 15/21) plants grown in nutrient solution with different Zn²⁺ supply. Compared to Zn-sufficient plants, the plasma membrane permeability of Zn-deficient plants was increased as indicated by a 3-, 5- and 2.5-fold increase in root cell leakage of K⁺, NO₃^- and organic carbon compounds, respectively. Resupply of Zn²⁺ to Zn-deficient plants for 12 h substantially decreased this leakage. The effects of Zn²⁺ on membrane permeability were closely correlated with the levels of O₂^- measured by electron spin resonance (ESR) spectroscopy in the microsomal membrane fraction and in the cytosol fraction of root cells. The amplitudes of the O₂^- -derived Tiron ESR signal also coincided with a O₂^- -generating oxidase activity which was strongly dependent on the presence of NADPH and FAD. The results suggest that Zn²⁺ directly affects the integrity of the plasma membrane, at least in part, by interfering with O₂^- generation by a membrane-bound NADPH oxidase.     

Design,synthesis and anticancer evaluation of novel pyrazole,pyrazolo[3,4-d]pyrimidine and their glycoside derivatives

The chalcone derivatives 3a,b were cyclized upon reaction with thiourea to give the pyrazolo[3,4-d]pyrimidine derivatives 5a,b. Condensation of 5a,b and their hydrazide derivatives 8a,b with cyclic and acyclic glucose gave the condensed S- and N-glycosides 7a,b and 9a,b, respectively. Reaction of 3b with ethyl cyanoacetate followed by reaction with cyclic glucose afforded a mixture of the O- and/or N-glycoside isomers 12 and 13, respectively. The pyrazolo[3,4-c]pyrazole derivative 14 was also obtained from the reaction of 3b with hydrazine hydrate. A number of the synthesized compounds were screened for their antitumor activity against three different tumor cell lines HEPG2 (liver), HCT116 (colon) and MCF-7 (breast) with a docking study against CDK2.     

A high-molecular-weight cysteine endopeptidase from rat skeletal muscle

A cytosolic enzyme of high molecular weight (about 500 000), which attacks native or denatured proteins (inter alia, casein, globin and hexokinase) was purified about 1000-fold from mixed rat skeletal muscles, including muscles freed of mast cells by prior treatment of the animals with the degranulator, compound 48/80. Peptides of varying size were generated from radioactively labelled globin, but no free amino acids were formed; free tyrosine was also not released from azocasein. The pH optimum was 7.5 and the presence of an essential cysteine group was suggested because dithiothreitol (1 mM) stimulated the activity and N-ethylmaleimide (5 mM) and p-chloromercuriphenylsulphonic acid (1 mM) were inhibitors. The activity was markedly inhibited by Zn2+ but not by leupeptin, chymostatin or pepstatin. The enzyme was stabilized by ATP, at concentrations as low as 0.1 mM, against inactivation at 42 degrees C. The endopeptidase was clearly separated on gel chromatography from another large protease, also sensitive to Zn2+, but with marked aminopeptidase activity and the properties of hydrolase H. The activity levels of the protease, assayed after chromatography on Sepharose 6B of high-speed supernatant fractions, did not vary significantly in skeletal muscle samples which were derived from denervated, starved, diabetic or hyperthyroid animals, in all of which the abnormal physiological states expressed themselves as enhanced rates of tyrosine released by incubated soleus and extensor digitorum longus muscles. Nevertheless, the enzyme described here may be part of an ATP-dependent, multi-component proteolytic system similar to that already known to be present in reticulocytes.     

Linear solvation energy relationship modeling and kinetic studies on reactive extraction of succinic acid by tridodecylamine dissolved in MIBK

Equilibrium and kinetic studies for the extraction of succinic acid from aqueous solution with tridodecylamine diluted in MIBK are reported. All measurements were carried out at 298.15 K. The extent to which the organic phase may be loaded with succinic acid is expressed as a loading ratio, Z. The equilibrium data were also interpreted by a proposed mechanism of three reactions of complexation by which (1:1) and (2:1) acid-amine complexes are formed. Kinetics of extraction of succinic acid by tridodecylamine in MIBK has also been determined. Kinetic studies for the extraction of succinic acid from aqueous solution with tridodecylamine diluted in MIBK were carried out using a stirred cell for kinetic studies. The results of the liquid-liquid equilibrium measurements were correlated by a linear solvation energy relationship (LSER) model, which takes into account physical interactions. From the regression coefficients, information on the solvent-solute interaction is obtained and solvation models are proposed.     

Isolation of Cronobacter spp. (formerly Enterobacter sakazakii) from infant food, herbs and environmental samples and the subsequent identification and confirmation of the isolates using biochemical, chromogenic assays, PCR and 16S rRNA sequencing

Background  

Cronobacter spp. (formerly Enterobacter sakazakii), are a group of Gram-negative pathogens that have been implicated as causative agents of meningitis and necrotizing enterocolitis in infants. The pathogens are linked to infant formula; however, they have also been isolated from a wide range of foods and environmental samples.