Extracellular membrane vesicles derived from Komagataeibacter oboediens exposed on the International Space Station fuse with artificial eukaryotic membranes in contrast to vesicles of reference bacterium.

Membranous Extracellular Vesicles (EVs) of Gram-negative bacteria are a secretion and delivery system that can disseminate bacterial products and interact with hosts and the environment. EVs of nonpathogenic bacteria deliver their contents by endocytosis into eukaryotic cells, however, no evidence exists for a fusion delivery mechanism. Here, we describe the fusion of exposed to space/Mars-like stressors simulated on the International Space Station vesicles (E-EVs) from Komagataeibacter oboediens to different types of model planar membranes in comparison with the EVs of the ground-based reference strain. The most reliable fusion was achieved with PC:PE:ergosterol or sterol-free PC:PE bilayers. The relative permeability ratio (PK+/PCl-) estimated from the shift of zero current potential according to Goldman-Hodgkin-Katz equation consisted of 4.17 ± 0.48, which coincides with preferential cation selectivity of the EV endogenous channels. The increase in membrane potential from 50 mV to 100 mV induced the fusion of E-EVs with all tested lipid compositions. The fusion of model exosomes with planar bilayer lipid membranes was confirmed by separate step-like increases in its conductance. In contrast, the ground-based reference K. oboediens EVs never induced the fusion event. In our study, we show membrane lipidome perturbations and increased protein aggregation occurred in the exposed samples in the harsh environment when outer membranes of K. oboediens acquired the capability of both homo- and heterotypic fusion possibly by altered membrane fluidity and the pore-forming capability.

Insecticidal properties of permethrin and permethrin-based agents.

A study of some insecticidal properties of a new pyrethroid, permethrin, showed that it was a highly effective insecticide at contact, superior in this respect to neopinamin for German cockroaches, houseflies and bedbugs and superior to sumithrin for German cockroaches. Combinations of permethrin with neopinamin displayed synergism. The most active combination contained permethrin and neopinamin in a ratio of 9:1. This combination surpassed in insecticidal activity the most effective combination of sumithrin with neopinamin.

Comparative insecticidal acitvity of sumithrin and neopinamine.

The examination of insecticidal properties of the new pyrethroid--sumithrin--showed this compound in contact action to be a highly effective insecticide, superior in activity to neopinamine. The intestinal action of sumithrin is less pronounced in comparison with neopinamine. Sumithrin is more selective in its effect on insects as compared with neopinamine. In the form of earosols, sumithrin and its mixtures with DDVP are less active than compositions based on neopinamine.

[Insecticidal properties of sumitrin]. / Insektitsidnye svoistva sumitrina

The study of insecticidal properties of sumitrin demonstrated that in contact action it was a highly effective insecticide; in topical application LD50 for domestic flies, bedbugs and cockroaches was 0.47, 1.25 and 3.26 mug/g, respectively. Sumitrin possessed high action selectivity for insects and low toxicity for warm-blooded animals (LD50 for albino mice greater than 7500 mg/kg). In the form of aerosols sumitrin and its mixtures with DDVF were less active than compositions on the neopinamine base.