Interaction-induced electric (hyper)polarizability in the dihydrogen–neon pair: basis set and electron correlation effects

We investigated the interaction (hyper)polarizability of neon–dihydrogen pairs by performing high-level ab initio calculations with atom/molecule-specific, purpose-oriented Gaussian basis sets. We obtained interaction-induced electric properties at the SCF, MP2, and CCSD levels of theory. At the CCSD level, for the T-shaped configuration, around the respective potential minimum of 6.437 a₀, the interaction-induced mean first hyperpolarizability varies for 5?<? R/a₀?<?10 as

$$ \left[{\overline{\beta}}_{\mathrm{int}}(R)\hbox{-} {\overline{\beta}}_{\mathrm{int}}\left({R}_{\mathrm{e}}\right)\right]/{e}^3{a_0}^3{E_{\mathrm{h}}}^{-2}=-0.91\left(R\hbox{-} {R}_{\mathrm{e}}\right)+0.50{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^2\hbox{--} 0.13{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^3+0.01{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^4. $$

Again, at the CCSD level, but for the L-shaped configuration around the respective potential minimum of 6.572 a₀, this property varies for 5?<? R/a₀?<?10 as

$$ \left[{\overline{\beta}}_{\mathrm{int}}(R)\hbox{-} {\overline{\beta}}_{\mathrm{int}}\left({R}_{\mathrm{e}}\right)\right]/{e}^3{a_0}^3{E_{\mathrm{h}}}^{-2}=-1.33\left(R\hbox{-} {R}_{\mathrm{e}}\right)+0.75{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^2-0.20{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^3+0.02{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^4. $$

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Graphical Abstract Interaction-induced mean dipole polarizability (\( \overline{a} \)) for the T-shaped configuration of H₂–Ne calculated at the SCF, MP2, and CCSD levels of theory

     

A Fusarium solani endophyte vs fungicides: Compatibility in a Fusarium oxysporum f.sp. radicis-lycopersici – tomato pathosystem

The potential of FsK, a non-pathogenic endophytic Fusarium solani strain, to be utilized as a biocontrol agent in combination with nine selected fungicides registered in tomato crops in Greece was evaluated. In vitro fungitoxicity tests revealed that FsK was insensitive to doses exceeding 100 μg/mL of thiophanate-methyl, fenhexamid, cyprodinil, boscalid and mancozeb. On the contrary, prochloraz, fludioxonil, pyraclostrobin and difenoconazole were most toxic to FsK. None of the later fungicides affected conidial production in an adverse way. Drenching of tomato plants with the above fungicides at recommended doses did not significantly affect colonization of tomato roots by FsK as revealed by in vitro isolation and Real Time PCR quantification. The disease suppressive ability of FsK against Fusarium oxysporum f.sp.radicis lycopersici (FORL) was not adversely affected by the post-inoculation application of commercial formulations of fludioxonil (Switch) and pyraclostrobin (Comet) at the recommended doses. Even more, the Comet–FsK combination resulted in enhanced disease suppression compared to either of the two treatments applied individually. In conclusion, not only biocontrol agent FsK is suitable for use in tomato integrated disease management programs that include all tested fungicides but also, some FsK –fungicide combinations can have additive effect against FORL disease incidence.     

Identifying critical migratory bottlenecks and high‐use areas for an endangered migratory soaring bird across three continents

Migrant birds face a number of threats throughout their annual cycle, including persecution, collision with energy infrastructure, and habitat and climate change. A key challenge for the conservation of migrants is the identification of important habitat, including migratory concentration areas, because species survival rates may be determined by events in geographically very limited areas. Remote‐tracking technology is facilitating the identification of such critical habitat, although the strategic identification of important sites and incorporation of such knowledge in conservation planning remains limited. We tracked 45 individuals of an endangered, soaring migrant (Egyptian vulture Neophron percnopterus), over 75 complete migrations that traversed three continents along the Red Sea Flyway. We summarize and contextualize migration statistics by season and age class, including migration start, midpoint, and end dates, as well as linear and cumulative migration distance, migration duration and speed, and route straightness. Then, using dynamic Brownian bridge movement models, we quantified space use to identify the most important migratory bottlenecks and high‐use areas on the flyway. These areas each accounted for < 5% of the overall movement range of the tracked birds, yet > 20% of all tracks passed through bottlenecks, and > 50% of the overall vulture time spent on migration fell within high‐use areas. The most important sites were located at the southeastern Red Sea coast and Bab‐el‐Mandeb Strait (Saudi Arabia, Yemen, Djibouti), the Suez Canal zone (Egypt), and the Gulf of Iskenderun (Turkey). Discouragingly however, none of the area within the major migratory bottlenecks was protected and < 13% of the high‐use areas were protected. This demonstrates a very concerning gap in the protected area network for migratory soaring birds along the Red Sea Flyway. Because reducing threats at migratory concentrations can be a very efficient approach to protect populations, our work provides clear guidelines where conservation investment is urgently needed to benefit as many as 35 migratory soaring‐bird species that regularly use the Red Sea Flyway.     

Chromatic regulation inChlamydomonas reinhardtii alters photosystem stoichiometry and improves the quantum efficiency of photosynthesis

The work addressed the adjustment of the photosystem ratio in the green algaChlamydomonas reinhardtii. It is shown that green algae, much like cyanophytes and higher plants, adjust and optimize the ratio of the two photosystems in chloroplasts in response to the quality of irradiance during growth. Such adjustments are compensation reactions and helpC. reinhardtii to retain a quantum efficiency of oxygen evolution near the theoretical maximum. Results show variable amounts of PS I and a fairly constant amount of PS II in chloroplasts and suggest that photosystem stoichiometry adjustments, occurring in response to the quality of irradiance during plant growth, are mainly an adjustment in the concentration of PS I. The work delineates chromatic effects on chlorophyll accumulation in the chloroplast ofC. reinhardtii from those pertaining to the regulation of the PS I/PS II ratio. The detection of the operation of a molecular feedback mechanism for the PS I/PS II ratio adjustment in green algae strengthens the notion of the highly conserved nature of this mechanism among probably all oxygen evolving photosynthetic organisms. Findings in this work are expected to serve as the basis of future biochemical and mutagenesis experiments for the elucidation of the photosystem ratio adjustment in oxygenic photosynthesis.     

Vanadium chemistry and biochemistry of relevance for use of vanadium compounds as antidiabetic agents

The stability of 11 vanadium compounds is tested under physiological conditions and in administration fluids. Several compounds including those currently used as insulin-mimetic agents in animal and human studies are stable upon dissolution in distilled water but lack such stability in distilled water at pH7. Complex lability may result in decomposition at neutral pH and thus may compromise the effectiveness of these compounds as therapeutic agents; Even well characterized vanadium compounds are surprisingly labile. Sufficiently stable complexes such as the VEDTA complex will only slowly reduce, however, none of the vanadium compounds currently used as insulin-mimetic agents show the high stability of the VEDTA complex. Both the bis(maltolato)oxovanadium(IV) and peroxovanadium complexes extend the insulin-mimetic action of vanadate in reducing cellular environments probably by increased lifetimes under physiological conditions and/or by decomposing to other insulin mimetic compounds. For example, treatment with two equivalents of glutathione or other thiols the (dipicolinato)peroxovanadate(V) forms 9dipicolinato)oxovanadate(V) and vanadate, which are both insulin-mimetic vanadium(V) compounds and can continue to act. The reactivity of vanadate under physiological conditions effects a multitude of biological responses. Other vanadium complexes may mimic insulin but not induce similar responses if the vanadate formation is blocked or reduced. We conclude that three properties, stability, lability and redox chemistry are critical to prolong the half-life of the insulin-mimetic form of vanadium compounds under physiological conditions and should all be considered in development of vanadium-based oral insulin-mimetic agents.Abbreviations ADP adenosine 5-diphosphate - ATP adenosine 5-triphosphate - ADP-V adenosine 5-diphosphate-vanadate - bpV bis(peroxo)oxovanadium(V) - (bpV)2 bis(peroxo)oxovanadium(V) dimer - bpVpic bis(peroxo)picolinatooxovanadate(V) - ¹³C carbon-13 - EDTA ethylenediaminetetraacetic acid - EPR electron paramagnetic resonance - EXSY exchange spectroscopy - ¹H proton - HSG glutathione - NAD -nicotinamide adenine dinucleotide - NADP -nicotinamide adenine dinucleotide phosphate - NADV -nicotinamide adenine dinucleotide vanadate - NMR nuclear magnetic resonance (also referred to as magnetic resonance imaging) - pVdipic (dipicolinato)peroxovanadate(V) - Vcit (citrato)dioxovanadate(V) - VEDTA (ethylenediaminetetraacetato)dioxovanadate(V) - Vmalto bis(maltolato)-oxovanadium(IV) - Voxal bis(oxalato)dioxovanadate(V) - ⁵¹V vanadium-51 - V₁ vanadate monomer - V₂ vanadate dimer - V₄ vanadate tetramer - V₅ vanadate pentamer - UV-vis spectroscopy ultraviolet-visible spectroscopy     

Disruption of IcsP, the major Shigella protease that cleaves IcsA, accelerates actin-based motility

Shigella pathogenesis involves bacterial invasion of colonic epithelial cells and movement of bacteria through the cytoplasm and into adjacent cells by means of actin-based motility. The Shigella protein IcsA (VirG) is unipolar on the bacterial surface and is both necessary and sufficient for actin-based motility. IcsA is inserted into the outer membrane as a 120-kDa polypeptide that is subsequently slowly cleaved, thereby releasing the 95-kDa amino-terminal portion into the culture supernatant. IcsP, the major Shigella protease that cleaves IcsA, was identified and cloned. It has significant sequence similarity to the E. coli serine proteases, OmpP and OmpT. Disruption of icsP in serotype 2a S. flexneri leads to a marked reduction in IcsA cleavage, increased amounts of IcsA associated with the bacterium and altered distribution of IcsA on the bacterial surface. The icsP mutant displays significantly increased rates of actin-based motility, with a mean speed 27% faster than the wild-type strain; moreover, a significantly greater percentage of the icsP mutant moves in the cytoplasm. Yet, plaque formation on epithelial monolayers by the mutant was not altered detectably. These data suggest that IcsA, and not a host protein, is limiting in the rate of actin-based motility of wild-type serotype 2a S. flexneri .