Fabrication of copper(II)-coated magnetic core-shell nanoparticles Fe3O4@SiO2-2-aminobenzohydrazide and investigation of its catalytic application in the synthesis of 1,2,3-triazole compounds

In the present work, an attempt has been made to synthesize the 1,2,3-triazole derivatives resulting from the click reaction, in a mild and green environment using the new copper(II)-coated magnetic core-shell nanoparticles Fe3O4@SiO2 modified by isatoic anhydride. The structure of the catalyst has been determined by XRD, FE-SEM, TGA, VSM, EDS, and FT-IR analyzes. The high efficiency and the ability to be recovered and reused for at least up to 6 consecutive runs are some superior properties of the catalyst.

Overview of ribosomal and non-ribosomal antimicrobial peptides produced by Gram positive bacteria

The increasing incidence of antimicrobial resistance bacterial infection and decreasing effectiveness of conventional antibiotics to treatment have caused serious problems worldwide. The demand for new generationantibiotics to combat microbial pathogens is imperative. Cationic antimicrobial peptides (AMPs) with different sources from prokaryotic to complex eukaryotic organisms, with variable length, amino acid composition and secondary structure, have been consideredduring the past decades.  The advantages of large number of AMPs are related to broad spectrum and morphogenetic activities, low resistance rate among microorganismswithout side effect on human cells, rapid killing of bacteria via membrane damage and intracellular targets,and their critical roles in anti-inflammatory. Ribosomal synthesized peptides of Gram positive bacteria with various post translational modificationsrepresent extended types of antimicrobial peptide with different structural and functional diversity. These types of peptides have been considered as new therapeutic agents for pharmaceutical development .In addition, non- ribosomal synthesized peptides are a wide range of peptides , an extremely extensive range of biological activities and pharmacological properties that are not synthesized by ribosomes,  show interesting biological properties ranging from antibiotic to bio surfactants. This review focused on genetics, mechanism of action and modifications, resistance mode of Gram positive bacteria to AMPs and the biotechnological application of ribosomally and non-ribosomally synthesized peptides derived from Gram positive bacteria.

Distribution of class 1 integrons among enteropathogenic Escherichia coli

The aim of this study was to investigate the incidence of and resistance gene content of class 1 integrons among enteropathogenic Escherichia coli (EPEC) and non-EPEC and to investigate intraspecies genetic diversity of EPEC strains isolated from children with diarrhea in Iran. Twenty-eight EPEC and 16 non-EPEC strains isolated from children with diarrhea were tested for the presence of a class 1 integron associated integrase gene (int1). Sequence analysis was performed to identify the resistance gene content of integrons. Genetic diversity and cluster analysis of EPEC isolates were also investigated using enterobacterial repetitive intergenic concensus-polymerase chain reaction (ERIC-PCR) fingerprinting. Twenty-three (82%) EPEC isolates and 11 (68.7%) non-EPEC isolates harbored the int1 gene specific to the conserved integrase region of class 1 integrons. Sequence analysis revealed the dominance of dfrA and aadA gene cassettes among the isolates of both groups. ERIC-PCR fingerprinting of EPEC isolates revealed a high diversity among these isolates. The widespread distribution of 2 resistance gene families (dfrA and aadA) among both groups of EPEC and non-EPEC isolates indicates the significance of integrons in antibiotic resistance transfer among these bacteria. Furthermore, clonal diversity of EPEC isolates harbouring a class 1 integron also suggests the circulation of these mobile elements among a diverse population of EPEC in this country.

Sequence Diversity in tRNA Gene Locus A-L among Iranian Isolates of Entamoeba dispar

BACKGROUND

A number of methods for detecting diversity in Entamoeba have been described over the years. In the present study the genetic polymorphism of noncoding locus A-L was analyzed using PCR and sequencing in order to clarify the genotypic differences among E. dispar isolates.

METHODS

A total of 28 E. dispar from patients with gastrointestinal symptoms were determined and the genomic DNA was extracted directly from stool. For genotype analysis; Locus A-L was amplified by PCR and PCR products were sequenced. The sequences obtained were edited manually and aligned using Gene Runner software.

RESULTS

With sequencing of PCR products a reliable genetic diversity in size, number and position of the repeat units were observed among the Iranian E. dispar isolates in locus A-L gene. Sequences showed variation in length from 448bp to 507bp and seven distinct types were identified.

CONCLUSION

The genetic diversity of loci like A-L shows them to be suitable for epidemiological studies such as the characterization of the routes of transmission of these parasites in Iran.

Fatal sepsis by Bacillus circulans in an immunocompromised patient

An immunosuppressed man was admitted to hospital with diarrhea and a history of urinary tract infection. He was subjected to treatment with antibiotics. The patient died of putative severe sepsis. The etiological agent was a carbapenemase producing isolate of Bacillus circulans with resistance to all prescribed antimicrobial agents.

Insecticidal properties of Verbascum cheiranthifolium against R. dominica on wheat and barley

Tissues of higher plants contain novel natural substances that can be used to develop environmental safe methods for insect control. In this study, ethanol extract from flowers of Verbascum cheiranthifolium Boiss. (Scrophulariaceae) was examined for their effect on mortality and progeny production against adults of Rhyzopertha dominica (F.) on two commodities, wheat and barley. The botanical extract was applied at five dose rates, which 0.25, 0.5, 1.0, 2.0 and 3% (w/v). Adults of R. dominica were exposed to the treated wheat and peeled barley at 25 degrees C and 65% RH and mortality was assessed after 24 h, 48 h, 7 day, 14 day and 21 day of exposure. Then all adults were removed and the treated substrate remained at the same conditions for an additional 45 day after this interval, the commodities were checked for progeny production. In two commodities mortality increased with the increase of dose and exposure interval. Results indicated that on wheat, mortality was 100% after 14 days of exposure at the highest dose rate. Whereas, in the same conditions mortality of adults on barley was 63%. Thus plant extract was more effective against adults of R. dominica on wheat than application of barley. Interestingly in two diets, complete suppression (100%) of the progeny production was observed in the treated wheat and barley than in control even in the lowest dose rate.

Physiological and cytological response of salt-tolerant and non-tolerant barley to salinity during germination and early growth

Seven barley cultivars (Franklin, Gairdner, YU6472, Numar, CM72, ZND3 and YUQS) were evaluated for NaCl tolerance in relation to physiological and cytological responses during germination. Standard germination techniques were employed using blotting paper saturated with different NaCl solutions (0, –0.3, –0.6, –0.9, –1.2, –1.5 or –1.8 MPa) at 20°C. The results showed significant differences among varieties for germination percentage, frequency of abnormal seedlings, and Na+, K+ uptake. Of the 7 barley cultivars, CM72 was similar in salt tolerance to Numar, while YUQS and ZND3 were the most sensitive to high salinity. The tolerant cultivars showed much higher germination percentage under salinity stress than susceptible varieties. Both CM72 and Numar maintained more than 90% germination at –1.2 MPa osmotic potential while YUQS and ZND3 had only 57% germination at the same level of salinity. The tolerant varieties also showed shorter mean germination time at low osmotic potential. The start of the first mitosis was delayed, while both the frequencies of aberrant anaphases at the first cell divisions, and the numbers of abnormal seedlings were increased in higher salt concentrations. During the seedling stage, tolerant varieties showed significantly higher K+ concentrations, lower Na+ concentrations, lower Na+/K+ ratio and higher photosynthetic rate than susceptible varieties under salinity stress. Screening of barley cultivars or breeding lines could be best achieved by a combination of germination testing and measurement of photosynthetic rate and/or Na/K balance in young seedlings.

Electron transfer to cytochrome P-450scc limits cholesterol-side-chain-cleavage activity in the human placenta

The aim of this study was to determine whether electron transfer from adrenodoxin reductase and adrenodoxin limits the activity of cytochrome P-450scc in mitochondria from the human placenta. Mitochondria were disrupted by sonication to enable exogenous adrenodoxin and adrenodoxin reductase to deliver electrons to cytochrome P-450scc. After sonication, the rate of pregnenolone synthesis was greatly decreased relative to that by intact mitochondria, due to dilution of endogenous adrenodoxin and adrenodoxin reductase into the incubation medium. The addition of saturating concentrations of bovine or human adrenodoxin and bovine adrenodoxin reductase to the disrupted mitochondria gave an initial rate of pregnenolone synthesis that was 6.3-fold higher than that for intact mitochondria. Similar results were observed when 20alpha-hydroxycholesterol was used as substrate rather than endogenous cholesterol. The turnover number of cytochrome P-450scc in sonicated placental mitochondria supplemented with adrenodoxin and adrenodoxin reductase was comparable to that for the purified enzyme assayed under conditions where electron transfer was not limiting. Addition of exogenous adrenodoxin and adrenodoxin reductase to sonicated mitochondria from the pig corpus luteum and rat adrenal had a much smaller effect on pregnenolone synthesis compared with intact mitochondria, than observed for the placenta. We conclude that in the human placenta, electron transfer to cytochrome P-450scc is limiting, permitting pregnenolone synthesis to proceed at only 16% maximum velocity.

A new procedure for the labeling of peptides and amino acids

Several stable, water soluble cyclohexa-2,4-dien-1-ones have been prepared and their photolytic coupling reactions in aqueous solution at 28 degrees C with various amino acids and dipeptides investigated. This procedure represents a new and high yielding method for the labeling of the terminal amino functionality of peptides and amino acids.

Digestive enzyme activities and their distribution in the alimentary canal of larvae of the three extant lamprey families

The activities of trypsin (EC 3.4.21.4), chymotrypsin (EC 3.4.21.1), lipase (EC 3.1.1.3) and amylase (EC 3.2.1.1) were measured in different regions of the alimentary tract of ammocoetes from each of the three extant lamprey families. In the southern hemisphere speciesGeotria australis (Geotriidae), and even more particularlyMordacia mordax (Mordaciidae), enzymatic activity was almost entirely confined to prominent diverticular extensions which arise at the oesophageal-intestinal junction. However, in the holarcticLampetra richardsoni (Petromyzontidae), which does not possess a diverticulum, the enzymatic activity was highest in the upper anterior intestine. It is not clear whether the presence of significantly higher amylolytic and lower lipolytic activities in the diverticulum ofG. australis than in the exocrine tissue of the other two species reflects interspecific differences in the composition of their diets. The capacity of exocrine tissue extracts for chymotryptic and tryptic digestion was assayed before and afterin vitro exposure to trypsin and enteropeptidase, their respective catalytic activators. Prior to exposure to these exogenous activators, both proteolytic enzymes were fully active inL. richardsoni, partially active inG. australis and totally inactive inM. mordax. Maximal chymotryptic activity was greater inM. mordax than inL. richardsoni andG. australis. In contrast, maximal tryptic activity was greater inL. richardsoni than inG. australis and was very low inM. mordax. Since trypsin is the only known activator of chymotrypsinogen, the negligible activity of trypsin inM. mordax would appear anomalous unless a trypsin inhibitor is present in the protopancreas of this species. Differences in the distribution of enzymatic activity within the alimentary tract of the three species is discussed in relation to proposed phylogenetic relationships amongst the extant lamprey families.

Impact of complete isletectomy on plasma glucose in the southern hemisphere lamprey Geotria australis

The adult southern hemisphere lamprey Geotria australis is the only known vertebrate in which it is possible to remove all of the pancreatic islet tissue without damaging other organs. In the 24 hr after isletectomy, the plasma glucose of adult G. australis rose sharply from 5.0 to 11.6 mmol.liter-1 and remained at a similar elevated level throughout the subsequent 5 days of the experiment. The marked hyperglycemia that follows complete isletectomy parallels the results obtained after removal of the majority of the islet tissue from northern hemisphere lampreys and after pancreatectomy in mammals, but contrasts with observations recorded for some other groups of vertebrates.