Insecticidal potential of natural zeolite and diatomaceous earth formulations against rice weevil (Coleoptera: Curculionidae) and red flour beetle (Coleoptera: Tenebrionidae)

Insecticidal potential of natural zeolites and diatomaceous earths originating from Serbia against Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) was evaluated. Two natural zeolite formulations (NZ and NZ Modified) were applied to wheat at rates of 0.50, 0.75, and 1.0 g/kg, while two diatomaceous earth (DE) formulations (DE S-1 and DE S-2) were applied at rates of 0.25, 0.50, 0.75, and 1.0 g/kg. A bioassay was conducted under laboratory conditions: temperature of 24 +/- 1 degrees C, relative humidity in the range 50-55%, in tests with natural zeolites, and 60-65%, in tests with DEs, and in all combinations for progeny production. Mortality was assessed after 7, 14, and 21 d of insect contact with treated wheat, and the total mortality after an additional 7-d recovery on untreated broken wheat. Progeny production was also assessed after 8 wk for S. oryzae and 12 wk for T. castaneum. The highest mortality for S. oryzae and T. castaneum was found after the longest exposure period and 7 d of recovery, on wheat treated with NZ at the highest rate and DEs at rates of 0.50 -1.0 g/kg. Progeny reduction higher than 90% was achieved after 14 and 21 d of contact of both beetle pests with wheat treated with DE S-1 at 0.50-1.0 g/kg and DE S-2 at 0.75-1.0 g/kg, while the same level of reduction was achieved only for T. castaneum after its contact with the highest rate of NZ formulation. NZ Modified, applied even at the highest rate, revealed much lower insecticidal potential.     

Modulation of the multilamellar membrane organization and of the chiral macrodomains in the diatom Phaeodactylum tricornutum revealed by small-angle neutron scattering and circular dichroism spectroscopy

Diatoms possess effective photoprotection mechanisms, which may involve reorganizations in the photosynthetic machinery. We have shown earlier, by using circular dichroism (CD) spectroscopy, that in Phaeodactylum tricornutum the pigment-protein complexes are arranged into chiral macrodomains, which have been proposed to be associated with the multilamellar organization of the thylakoid membranes and shown to be capable of undergoing light-induced reversible reorganizations (Szabó et al. Photosynth Res 95:237, 2008). Recently, by using small-angle neutron scattering (SANS) on the same algal cells we have determined the repeat distances and revealed reversible light-induced reorganizations in the lamellar order of thylakoids (Nagy et al. Biochem J 436:225, 2011). In this study, we show that in moderately heat-treated samples, the weakening of the lamellar order is accompanied by the diminishment of the psi-type CD signal associated with the long-range chiral order of the chromophores (psi, polymer or salt-induced). Further, we show that the light-induced reversible increase in the psi-type CD is associated with swelling in the membrane system, with magnitudes larger in high light than in low light. In contrast, shrinkage of the membrane system, induced by sorbitol, brings about a decrease in the psi-type CD signal; this shrinkage also diminishes the non-photochemical quenching capability of the cells. These data shed light on the origin of the psi-type CD signal, and confirm that both CD spectroscopy and SANS provide valuable information on the macro-organization of the thylakoid membranes and their dynamic properties; these parameters are evidently of interest with regard to the photoprotection in whole algal cells.     

Genome sequence of the human- and animal-pathogenic strain Nocardia cyriacigeorgica GUH-2

The pathogenic strain Nocardia cyriacigeorgica GUH-2 was isolated from a fatal human nocardiosis case, and its genome was sequenced. The complete genomic sequence of this strain contains 6,194,645 bp, an average G+C content of 68.37%, and no plasmids. We also identified several protein-coding genes to which N. cyriacigeorgica's virulence can potentially be attributed.     

Chemical and principal-component analyses of the essential oils of Apioideae taxa (Apiaceae) from central Balkan

The volatile constituents of the essential oils of 23 taxa belonging to the Apioideae subfamily were studied in detail. The investigated taxa were Pimpinella serbica (Vis.) Bentham & Hooker, Libanotis montana Cr., Cnidium silaifolium (Jacq.) Simk. ssp. orientale (Boiss.) Tutin, Bupleurum praealtum L., B. sibthorpianum S. S. var. diversifolium (Roch.) Hay, Aegopodium podagraria L., Torilis anthriscus (L.) Gmel., Orlaya grandiflora (L.) Hoffm., Laserpitium siler L., Laser trilobum (L.) Brokh., Chaerophyllum aureum L., C. hirsutum L., C. temulum L., Pastinaca sativa L., P. hirsuta Pancic., Tordylium maximum L., Physospermum cornubiense (L.) DC., Peucedanum alsaticum L., P. oreoselinum (L.) Moench, P. cervaria (L.) Cuss., P. austriacum (Jacq.) Koch, P. longifolium W. et K., and P. officinale L. All of these species grow wild in the central part of the Balkan Peninsula. The essential oils were found to be complex mixtures of various compounds, more than 100 constituents being in each taxon, with contributions of main products never exceeding 25% of the total content. Sesquiterpene hydrocarbons were found to be the main group of constituents of all taxa, except for Peucedanum species, where monoterpene hydrocarbons were identified as the main components. The chemotaxonomic value of the essential-oil composition is discussed according to results of principal-component analysis (PCA). The essential-oil composition mainly reflects current taxonomic relationships between the investigated taxa.     

Screening method for detection of hydrocarbon-oxidizing bacteria in oil-contaminated water and soil specimens

Toxic action of crude oil on the living world and ecosystems in general is a global problem of both aquatic and terrestrial environments. Bearing in mind the possibility of biodegradation of this toxicant, the procedures of determining counts and activity of cultivable microorganisms, and especially of bacteria responsible for degradation processes, are of great significance. The aim of this work was to study the possibility of modifying some solid media by adding triphenyltetrazolium chloride reagent as an indicator of the dehydrogenase activity, to develop a simple screening method for a simultaneous assessment of the count and activity of cultivable hydrocarbon-oxidizing bacteria in the oil-contaminated environments. The modified method appeared to be rapid and very suitable for the intended purposes.     

A colorimetric microtiter plate method for assessment of phage effect on Pseudomonas aeruginosa biofilm

Bacteriophages have a potential in biofilm control. The aim of the study was to develop a method for selection of the most effective Pseudomonas aeruginosa phages for inhibition of biofilm formation and its eradication. The microtiter plate method is based on crystal violet staining and measuring of optical density.     

Synthesis,characterization and nociceptive screening of new VV-hemorphin-5 analogues

In the present study, some new analogues of VV-hemorphin-5, modified at position 1 and 7 by the non-proteinogenic and/or natural amino acids followed the structures Xxx-Val-Val-Tyr-Pro-Trp-Thr-Gln-NH₂ and Val-Val-Tyr-Pro-Trp-Thr-Yyy-NH₂, where Xxx is Ile or Aib and Yyy is Lys/Orn/Dap/Dab were synthesized to investigate their potential antinociceptive activities. We report also the redox potentials and the acid/base properties as pKa values of these peptide analogues which were compared toward electrochemical behaviour of tryptophan containing peptides. All analogues showed a short lasting initial antinociceptive effect, however H2 hemorphin analogue is characterized with prolong and strong antinociceptive effect, while the other peptide analogues exerted more variable effects on the visceral nociception depending on the dose or time after the intracerebral injection.     

Pericarp structure and myxocarpy in selected genera of Nepetoideae (Lamiaceae)

The pericarp structure has been analyzed in 37 species representing 13 genera from four tribes of Nepetoideae (Lamiaceae). 11 species are endemics of Balkan Peninsula or other Mediterranean regions. Basically, the pericarp was similar to other Nepetoideae by having exocarp, mesocarp s. str., vertically arranged bone cells and thin innermost cell layer. The ratio between pericarp thickness and nutlet size was the highest in Mentha spp. According to this parameter Micromeria species belonging to different sections could be distinguished. Acinos spp. were characterized by the thickest sclerenchyma in ratio to pericarp thickness. Crystals were present within sclerenchyma region in genera Mentha, Melissa, Nepeta and Prunella . The mucilage production has also been tested. Most of the studied species produced mucilage when becoming wet. The strongest mucilage reaction showed Acinos and Prunella . Pericarp characters studied are of taxonomical interest. They were mainly correlated with the generic or infrageneric classification of some genera.