Impacts of the invasive hornet Vespa velutina on native wasp species: a first effort to understand population-level effects in an invaded area of Europe

Journal of Insect Conservation - Invasive alien species could generate a multitude of impacts towards native species. The introduction and spread of Vespa velutina in Europe is raising concern for...     

A controlled short-term exposure study to investigate the odor differences among three different formulations of gasoline

Control subjects (CON) and self-reported methyl tertiary butyl ether (MTBE)-sensitive subjects (SRS) were evaluated to distinguish between the following gasoline blends: gasoline versus gasoline + MTBE (15% MTBE v/v); and gasoline versus gasoline + MTBE + reodorant. The study also investigated the ability of a reodorant to conceal the odor of MTBE in a gasoline mixture. In each of two separate sessions, seven men (four CON, three SRS) and seven women (four CON, three SRS) were asked, in a forced-choice format, to sniff 28 randomized bottle pairs to determine if the odors in each pair were the same or different. Chi-square analyses revealed that, with the exception of one male CON, subjects were unable to distinguish between gasoline and gasoline with MTBE or gasoline with MTBE and the reodorant. Thus, a reodorant is of limited value as an additive which alters the ability of an individual to detect MTBE in a blended gasoline. The results suggest that at the level used in the experiment, no mask would be required to blind a participant from the odor of MTBE if that level is used in a controlled human health effects study of the additive.     

Characterization of diacetylenic liposomes as carriers for oral vaccines

In order to evaluate liposomes as vehicle for oral vaccines the characterization and stability of polymerized and non-polymerized liposomes were examined. Mixtures of 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3 phosphocholine) (DC8,9PC) with saturated 1,2-dimiristoyl-sn-glycero-3-phosphocholine in molar ratio 1:1 were used. Saturated and non-saturated lipids were combined to give a chemically modified membrane by UV polymerization derived from DC8,9PC. Characterization was carried out by electronic microscopy, differential scanning calorimetry (DSC) and by hydrophobicity factor (HF). The stability towards the digestive tract (including saliva): acidic solutions, bile and pancreatin are compared to buffer pH 7.4, measuring the release of Glucose-6-phosphate or bovine plasma albumin entrapment. The polymerized liposomes showed further augmentation of the HF and the size. DSC showed phase separation and lower Tt if compared to data obtained for DC8,9PC. The HF, as main factor is discussed in relation to in vitro stability, suggesting that polymerized and non-polymerized liposomes would serve effectively as an oral delivery vehicle.     

Aminoglycoside resistance 16S rRNA methyltransferases block endogenous methylation,affect translation efficiency and fitness of the host

In Gram-negative bacteria, acquired 16S rRNA methyltransferases ArmA and NpmA confer high-level resistance to all clinically useful aminoglycosides by modifying, respectively, G1405 and A1408 in the A-site. These enzymes must coexist with several endogenous methyltransferases that are essential for fine-tuning of the decoding center, such as RsmH and RsmI in Escherichia coli, which methylate C1402 and RsmF C1407. The resistance methyltransferases have a contrasting distribution—ArmA has spread worldwide, whereas a single clinical isolate producing NpmA has been reported. The rate of dissemination of resistance depends on the fitness cost associated with its expression. We have compared ArmA and NpmA in isogenic Escherichia coli harboring the corresponding structural genes and their inactive point mutants cloned under the control of their native constitutive promoter in the stable plasmid pGB2. Growth rate determination and competition experiments showed that ArmA had a fitness cost due to methylation of G1405, whereas NpmA conferred only a slight disadvantage to the host due to production of the enzyme. MALDI MS indicated that ArmA impeded one of the methylations at C1402 by RsmI, and not at C1407 as previously proposed, whereas NpmA blocked the activity of RsmF at C1407. A dual luciferase assay showed that methylation at G1405 and A1408 and lack of methylation at C1407 affect translation accuracy. These results indicate that resistance methyltransferases impair endogenous methylation with different consequences on cell fitness.     

The ζ toxin induces a set of protective responses and dormancy

The ζε module consists of a labile antitoxin protein, ε, which in dimer form (ε(2)) interferes with the action of the long-living monomeric ζ phosphotransferase toxin through protein complex formation. Toxin ζ, which inhibits cell wall biosynthesis and may be bactericide in nature, at or near physiological concentrations induces reversible cessation of Bacillus subtilis proliferation (protective dormancy) by targeting essential metabolic functions followed by propidium iodide (PI) staining in a fraction (20-30%) of the population and selects a subpopulation of cells that exhibit non-inheritable tolerance (1-5×10(-5)). Early after induction ζ toxin alters the expression of ～78 genes, with the up-regulation of relA among them. RelA contributes to enforce toxin-induced dormancy. At later times, free active ζ decreases synthesis of macromolecules and releases intracellular K(+). We propose that ζ toxin induces reversible protective dormancy and permeation to PI, and expression of ε(2) antitoxin reverses these effects. At later times, toxin expression is followed by death of a small fraction (～10%) of PI stained cells that exited earlier or did not enter into the dormant state. Recovery from stress leads to de novo synthesis of ε(2) antitoxin, which blocks ATP binding by ζ toxin, thereby inhibiting its phosphotransferase activity.     

Baroreceptor influence on a spinal cardiovascular reflex

A stretch of the walls of the thoracic aorta, performed in vagotomized cats without obstructing aortic flow, induces increases in heart rate, myocardial contractility, and arterial pressure. These reflex responses are still present after high spinal section. Cats under chloralose-urethane anesthesia were vagotomized and one carotid sinus was isolated and perfused with arterial blood at constant flow. The contralateral carotid sinus nerve and both aortic nerves were sectioned. A stretch of the walls of the thoracic aorta between the 7th and 10th intercostal arteries induced a reflex increase in mean arterial pressure 29 +/- 2 mmHg (mean +/- SE). Stepwise increases of carotid sinus pressure (CSP) or electrical stimulation of the carotid sinus nerve induced stepwise decreases of this reflex response. At maximal baroreceptor stimulation (CSP 212 +/- 9 mmHg) the reflex response to aortic stretch was reduced by 42%. These experiments show that this spinal cardiovascular reflex is at least partially under the inhibitory control of the baroreceptor input.     

Viability of thermal imaging in detecting nests of the invasive hornet Vespa velutina

Vespa velutina is an invasive hornet species that is colonising Europe,generating considerable impacts on honeybees,beekeeping and biodiversity.Control and early warning strategies for this species are mainly based on monitoring plans and procedures of nest detection and destruction.Technological tools(harmonic radar,radio-telemetry)have been developed to increase the probabilities of nest detection in new outbreaks.Since hornets are able to regulate nest temperature,thermography may represent an additional technique that may be used,both alone or in support to other techniques.In this study,the viability of thermal imaging in detecting nests of V.velutina was evaluated in controlled conditions.The influence of different environmental and operative variables(time of the day,presence/absence of leaves covering the nest,distance between the nest and the operator)were tested on three nests detected during August 2018 in Italy.All the nests were detectable by thermal imaging,but environmental and operative variables affect their detectability.The temperature difference between the nests and the surrounding reaches its maximum before sunrise and without a tree canopy covering the nests.Although nests were visible in some cases from 30 m,the detectability was higher at shorter distances,even if this variable may also depend on infrared camera resolution.An increase in the environmental temperature also generates a decrease of nest detectability.Although some limitations could occur,these results show the applicability of thermography in detecting V velutina nests before the beginning of the reproductive phase,and consequently its potentiality in control strategies.