Combined use of the larvo‐pupal parasitoids Diachasmimorpha longicaudata and Aganaspis daci for biological control of the medfly

In biological control programmes, it is very common to employ multiple species to manage a single insect pest. However, the beneficial effects of natural enemies are not always additive because of several factors, including interspecific competition between these biocontrol agents. For this reason, in the present study we assessed several biological parameters (percentage parasitism, fertility, induced mortality and population reduction) of the parasitoids Diachasmimorpha longicaudata and Aganaspis daci when used together against the medfly Ceratitis capitata under laboratory and greenhouse conditions. Our results showed that, under laboratory conditions, fertility and percentage parasitism corresponded to a different functional response for each species (D. longicaudata: type II; A. daci: type III), whilst under greenhouse conditions, and unlike what occurs with single releases, both parasitoids showed a type III functional response; this is the only response which may lead to direct density dependence when host densities are low. Our results also revealed that when both species acted together, they produced a very high total percentage parasitism compared to that reported for single releases under both laboratory (64–76%) and greenhouse (21–51%) conditions. The parasitism was also higher for A. daci except when medfly larvae were provided in an artificial diet. Furthermore, host mortality induced by the two parasitoids acting together was very high, especially at low‐host densities; medfly population was almost completely reduced under greenhouse conditions. In summary, the data reported here supports the combined use of these species in biological control programmes against the medfly and highlights the importance of several factors, such as climatic conditions and host density, when planning their field releases.     

Phylogenetic Analysis and Epidemic History of Hepatitis C Virus Genotype 2 in Tunisia,North Africa

HCV genotype 2 (HCV-2) has a worldwide distribution with prevalence rates that vary from country to country. High genetic diversity and long-term endemicity were suggested in West African countries. A global dispersal of HCV-2 would have occurred during the 20^th century, especially in European countries. In Tunisia, genotype 2 was the second prevalent genotype after genotype 1 and most isolates belong to subtypes 2c and 2k. In this study, phylogenetic analyses based on the NS5B genomic sequences of 113 Tunisian HCV isolates from subtypes 2c and 2k were carried out. A Bayesian coalescent-based framework was used to estimate the origin and the spread of these subtypes circulating in Tunisia. Phylogenetic analyses of HCV-2c sequences suggest the absence of country-specific or time-specific variants. In contrast, the phylogenetic grouping of HCV-2k sequences shows the existence of two major genetic clusters that may represent two distinct circulating variants. Coalescent analysis indicated a most recent common ancestor (tMRCA) of Tunisian HCV-2c around 1886 (1869–1902) before the introduction of HCV-2k in 1901 (1867–1931). Our findings suggest that the introduction of HCV-2c in Tunisia is possibly a result of population movements between Tunisia and European population following the French colonization.     

Novel components of the human metabolome: the identification, characterization and anti-inflammatory activity of two 5-androstene tetrols

Two natural 5-androstene steroid tetrols, androst-5-ene-3β,7β,16α,17β-tetrol (HE3177) and androst-5-ene-3α,7β,16α,17β-tetrol (HE3413), were discovered in human plasma and urine. These compounds had significant aqueous solubility, did not bind or transactivate steroid-binding nuclear hormone receptors, and were not immunosuppressive in murine mixed-lymphocyte studies. Both compounds appear to be metabolic end products, as they were resistant to primary and secondary metabolism. Both were orally bioavailable, and were very well tolerated in a two-week dose-intensive toxicity study in mice. Anti-inflammatory properties were found with exogenous administration of these compounds in rodent disease models of multiple sclerosis, lung injury, chronic prostatitis, and colitis.     

Pharmacology and immune modulating properties of 5-androstene-3β,7β,17β-triol, a DHEA metabolite in the human metabolome

Androst-5-ene-3β,7β,17β-triol (βAET) is an anti-inflammatory metabolite of DHEA that is found naturally in humans, but in rodents only after exogenous DHEA administration. Unlike DHEA, C-7-oxidized DHEA metabolites cannot be metabolized into potent androgens or estrogens, and are not peroxisome proliferators in rodents. The objective of our current studies was to characterize the pharmacology of βAET to enable clinical trials in humans. The pharmacology of βAET was characterized by pharmacokinetics, drug metabolism, nuclear hormone receptor interactions, androgenicity, estrogenicity, and systemic toxicity studies. βAET's acute anti-inflammatory activity and immune modulating characteristics were measured in vitro in RAW264.7 cells and in vivo in murine models with parenteral administration. βAET was rapidly metabolized and cleared from circulation in mice and monkeys. βAET was weakly androgenic and estrogenic in immature rodents, but not bound by androgen, estrogen, progesterone, or glucocorticoid nuclear hormone receptors. βAET did not induce peroxisome proliferation, nor was it systemically toxic or trophic for sex hormone responsive tissues in mature rats and monkeys. βAET significantly attenuated acute inflammation both in vitro and in vivo, augmented immune responses in adult mice, and reversed immune senescence in aged mice. βAET may contribute to the anti-inflammatory activity in rodents attributed to DHEA. Unlike DHEA, βAET's anti-inflammatory activity cannot be ascribed to activation of PPARs, androgen, or estrogen nuclear hormone receptors. Exogenous βAET is unlikely to produce untoward toxicity or hormonal perturbations in humans.     

Possible involvement of polyphenols and polyamines in salt tolerance of almond rootstocks

Leaf physiological and biochemical adaptive strategies and more particularly the possible involvement of polyamines and polyphenols in salt stress tolerance were investigated. Three almond rootstocks (GN15, GF677 and bitter almond) were subjected to 0, 25, 50 and 75 mM NaCl for 30 days. The dry mass of leaves, stems and roots decreased with increasing salt concentration in the irrigation solution regardless of genotype. Photosynthetic assimilation rate decreased in the three almond rootstocks, but more so in GF677 and bitter almond. The accumulation of toxic ions was greater in the leaves than in the roots in all genotypes. GN15 accumulated less Na⁺ and Cl⁻ than GF677 and bitter almond. GF677 accumulated polyphenols, but had less anthocyanin and antioxidant activity in its leaves compared to bitter almond. It seems that GN15 was more able to tolerate the excess of toxic ions using anthocyanins which are abundant in its red leaves and free polyamines for a more efficient response to stress. However, most of the antioxidant activity was found in the leaves and was lower in the roots. Given that the upper part of the tree will be of a different cultivar after grafting, this advantage may not be relevant for the tree’s survival. GF677 showed a different antioxidant strategy; it maintained a stable carotenoids content and accumulated polyphenols in its leaves. The three rootstocks used different strategies to deal with the excess of salt in the growth medium.     

Appropriateness of empiric antimicrobial therapy with imipenem/colistin in severe septic patients: observational cohort study

Background

Empiric antimicrobial therapy (EAMT) using imipenem/colistin is commonly prescribed as a first line therapy in critically ill patients with severe sepsis. We aimed to assess the appropriateness of prescribing imipenem/colistin as EAMT in ICU patients.

Methods

A 3-year observational prospective study included ICU patients that required imipenem/colistin as EAMT. The EAMT was assessed according to microbiological and clinical outcomes. The outcomes were: delay in apyrexia, delay in the decrease of the biological inflammatory parameters (BIP), the requirement for vasoactive agents, bacteriological eradication, length of stay, ventilator days and 30-day mortality.

Results

79 administrations of EAMT in 70 patients were studied. EAMT was appropriate in 52% of the studied cases. An ICU stay?>?6 days was related to inappropriateness, and chronic respiratory failure was associated with appropriateness. In the appropriate EAMT group, we showed: earlier apyrexia, shorter delay in the decrease of the BIP and a reduced significant vasopressors requirement. Furthermore, EAMT improved survival with a median gain of 4 days. Inappropriate EAMT increased the mortality risk by six. The acquisition of NI in ICU was also an independent factor of mortality.

Conclusions

EAMT using imipenem-colistin was appropriate in half of the cases and inappropriateness was associated with an increased ICU mortality risk.

     

A putative endophytic Bacillus cereus str. S42 from Nicotiana glauca for biocontrol of Fusarium wilt disease in tomato and gas chromatography-mass spectrometry analysis of its chloroform extract

A putative endophytic Bacillus cereus str. S42 (KP993206), recovered from surface-sterilised stems of Nicotiana glauca was assessed in vitro and in vivo for its antifungal potential towards Fusarium oxysporum f. sp. lycopersici (FOL). Pathogen sporulation was significantly inhibited by B. cereus str. S42. FOL mycelial growth was reduced using its whole-cell suspensions, cell-free culture supernatant and chloroform extract. Its extracellular metabolites remained effective after heating at 50–100 °C with a decline in their activity was observed beyond 100 °C, when added with proteinase K and/or after pH adjustment to 2 and 12. Chitinase gene was detected using PCR amplification. Gas chromatography–mass spectrometry analysis of its chloroform extract matched phthalic acid, dibutyl ester with high level of similarity. B. cereus str. S42 cell-free culture supernatant and whole-cell suspensions had significantly suppressed Fusarium wilt severity by 87–96% and enhanced tomato growth by 39–79% compared to FOL-inoculated and untreated control.     

Metabolic capacities and toxigenic potential as key drivers of Bacillus cereus ubiquity and adaptation

Bacillus cereus is ubiquitous and is commonly found in a wide range of environments, including food. In this study, we analyzed 114 foodborne B. cereus strains isolated mainly from starchy and dairy products in order to investigate their phenotypic diversity (API system), antimicrobial resistance and toxigenic profiles (hblA, nheA, hlyII, cereolysin O, cytK2, cytK1 and EM1 genes). All isolates were confirmed as B. cereus using their 16–23S ribosomal DNA intergenic transcribed spacer (ITS) signature, and were shown to be Gram-positive, catalase and caseinase positive, hemolytic (97 %), and positive for lecithin hydrolysis and motility (97 and 87 %, respectively). PCR detection of B. cereus-specific toxin genes revealed occurrence rates of 100 % for cereolysin O, 98 % for nheA, 74 % for cytk2, 52 % for hblA, 28 % for hlyII, and the absence of cytK1. Only two strains (2 %), isolated from intestine of boar and pheasant, carried the emetic toxin genetic determinants (ces). The antimicrobial susceptibility of isolates was tested towards 15 different antimicrobial agents. We detected susceptibility of all strains to most antibiotics, intermediate resistance to clindamycin, and resistance to β-lactam antibiotics with 83 % of the resistant isolates producing β-lactamase enzyme. This large phenotypic diversity, combined with the toxigenic traits and antibiotic resistance, emphasize the high potential risk of food poisoning of B. cereus isolates. Additionally, a clear correlation between the metabolic features and the origin of isolation was shown. Most starchy isolates were able to hydrolyze starch while dairy strains were not able to produce amylases. Overall, our results reveal that metabolic flexibility and toxigenic potential represent the main drivers for B. cereus ubiquity and adaptation in a given ecological niche.     

Lysosomes of the Liver and the Duodenal Enterocytes,a Site of Handling of Two Rare Earths. Ultrastructural and Microanalytical Study

The frequent use of some trace elements such as gadolinium and terbium in medicine and modern industries make us worry about their behavior in the organism. In this work, we study the intracellular localization in the liver and in the intestinal mucosa of two rare earths, gadolinium and terbium, after intraperitoneal and intragastric administration. Three methods of observation and microanalysis were used: conventional transmission electron microscopy, secondary ion mass spectrometry, and electron probe microanalysis. After intraperitoneal administration, gadolinium and terbium were detected with phosphorus in lysosomes of hepatocytes and Küppfer cells and in territories near to biliary canalicule. One hour after intragastric administration, gadolinium and terbium were concentrated in lysosomes of the apical part of duodenal enterocytes. No gadolinium or terbium was detected in duodenum 4 days after administration. After intragastric administration, the microanalytical techniques failed to detect gadolinium or terbium in liver whatever the time of sampling. This mechanism of concentration-precipitation in the lysosomes of enterocytes limits the diffusion through the digestive barrier of foreign elements and then permits their elimination with apoptotic cells in the intestinal lumen. Some of these elements may be toxic, and none of them have a recognized physiological function. The intestinal mucosa plays an important role in the protection of the organism against the invasion of foreign elements.