New antibiotic no. 792 formed by Actinomyces bottropensis

An actinomycetes strain 792 producing a new antibiotic was isolated under the programme of antitumor antibiotic screening. By its morphological and cultural properties strain 792 was classified as belonging to species Actinomyces bottropensis. Antibiotic 792 was recovered from the culture fluid of the strain by the extraction method in the form of a crystalline orange substances. lambda max 235, 305, 410 nm (E 1% 1cm 705, 105, 168), m. p. 232-255 degrees (dec), molecular weight 340, C 67 per cent, H 4.8 per cent, no nitrogen, sulphur or halogens. The antibiotic was inactivated in alkaline solutions forming a hardly soluble compound crystallizing in the form of red needles, lambda max 256, 485 nm (E 1% 1ct 800, 195), m. p. 202-204 degrees (dec), molecular weight 320, C 69.5 per cent, H 4.7 per cent. Antibiotic 792 had antitumor and antimicrobial activity.     

Lipid composition of gametes and embryos of the sea urchin Strongylocentrotus intermedius at early stages of development

The lipid composition of sea urchin gametes and embryos was examined in detail by micro thin-layer chromatography (tlc) and gas-liquid chromatography (glc). Lipids of unfertilized eggs contain 53.7% triglycerides, 33.2% phospholipids, and 9.4% cholesterol, while spermatozoa lipids consist of 65.0% phospholipids, 15.5% cholesterol, and no triglycerides. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), diphosphatidylglycerol (DPG), and lysophosphatidylcholine (LPC) were identified among the phospholipids of both eggs and spermatozoa. The major part of egg and embryo PE was present as plasmalogen. After fertilization and the first cleavage, phospholipid content decreased from 33.2 to 29.4%, but the amount of phospholipids returned to the 33.2% level by the blastula stage and reached 39.7% by the pluteus stage. Lipid class composition showed no qualitative changes during development, but concentrations of PE, PS, LPC, and cholesterol increased, while those of PC, PI, and triglycerides decreased during the process. The principal fatty acids of neutral and polar lipid fractions are 14:0, 16:0, 18:1, 18:4, 20:1, 20:4, and 20:5. Their relative content underwent some changes during development.     

In vitro oligomerization of a membrane protein complex. liposome-based reconstitution of trimeric photosystem I from isolated monomers.

Many membrane proteins can be isolated in different oligomeric forms. Photosystem I (PSI), for example, exists in cyanobacteria either as a monomeric or as a trimeric complex. Neither the factors responsible for the specific trimerization process nor its biological role are known at present. In the filamentous cyanobacterium Spirulina platensis, trimers in contrast to monomers show chlorophyll fluorescence emission at 760 nm. To investigate the oligomerization process as well as the nature of the long wavelength chlorophylls, we describe here an in vitro reconstitution procedure to assemble trimeric PS I from isolated purified PS I monomers. Monomers (and trimers) were extracted from S. platensis with n-dodecyl beta-D-maltoside and further purified by perfusion chromatography steps. The isolated complexes had the same polypeptide composition as other cyanobacteria (PsaA-PsaF and PsaI-PsaM), as determined from high resolution gels and immunoblotting. They were incorporated into proteoliposomes, which had been prepared by the detergent absorption method, starting from a phosphatidylcholine:phosphatidic acid mixture solubilized by octylglucoside. After the addition of monomeric PS I (lipid:chlorophyll, 25:1), octylglucoside was gradually removed by the stepwise addition of Biobeads. The 77 K fluorescence emission spectrum of these proteoliposomes displays a long wavelength emission at 760 nm that is characteristic of PS I trimers, which indicates for the first time the successful in vitro reconstitution of PS I trimers. In addition, a high performance liquid chromatography analysis of complexes extracted from these proteoliposomes confirms the formation of structural trimers. We also could show with this system 1) that at least one of the stromal subunits PsaC, -D, and -E is necessary for trimer formation and 2) that the extreme long wavelength emitting chlorophyll is formed as a result of trimer formation.     

Diamagnetic dilution due to the phase spin transition – An opportunity for the EPR study of intercluster exchange in “breathing” crystals of copper(II) hexafluoroacetylacetonate with pyrazole-substituted nitronyl nitroxide

Chain complex of copper(II) hexafluoroacetylacetonate with pyrazole-substituted nitronyl nitroxide containing exchange-coupled copper(II)–nitroxide clusters has been studied using electron paramagnetic resonance (EPR) spectroscopy. The structural rearrangements at low temperatures induce spin transitions in one half of the copper(II)–nitroxide clusters and effectively lead to reversible diamagnetic dilution. This results in significant changes of EPR spectra and allows us to obtain the value of dipole–dipole interaction in exchange-coupled spin pair as well as the value of exchange interaction between neighboring pairs.     

Structure and function of microbial communities in soil from the southern Taiga

General regularities in the structure of the microbial communities of southern taiga soil ecosystems and taxonomic differences between the microbial communities of soils with different hydrothermal characteristics are discussed with reference to the main types of soils of the Central State Forest Biosphere Reserve.     

The structure of micromycete communities and their synecologic interactions with basidiomycetes during decomposition of plant debris

We investigated the interactions between micromycetes and basidiomycete mycelium on plant substrates in the course of their 3-year incubation in the litter of ecologically intact spruce forests of the Central State Biosphere Forest Sanctuary (Nelidovo District, Tver oblast). Only 40-60% of the micromycetes were involved in direct antagonistic interactions with basidiomycetous fungi. In terms of the ratio between physiologically active strains and those which did not interact with basidiomycete mycelium, we revealed differences in the structure of micromycete communities developing on various types of substrates (xylem, bark, sphagnum, leaves, needles, litter, and cotton grass). The micromycetes tested belonged to 49 species. At the end of the observation period, the fraction of microscopic fungi that actively influenced basidiomycete mycelium was four times lower in the inactive litter fraction (lignin-containing xylem debris) than in the active fraction (grass substrates). The mechanisms of indirect regulation of the structure and functions of micromycete communities are discussed, which may be based on the accumulation of phenolic compounds in the medium and changes in the enzyme activities of basidiomycete mycelium.     

The hypolipidemic action of antibiotic 86/88 (enniatin B) in a hepatoblastoma G2 cell culture]

A cyclodepsipeptide antibiotic 86/88 (enniatin B) with strong hypolipidemic action was isolated from the culture liquid of the fungus INA F-86/88 identified as Fusarium lateritium Nees var. stilboides (Wr.) Bilai. In the Hep G2 cell culture the antibiotic suppressed 14C-acetate incorporation into cholesterol (IC50 1.75 microM), cholesterol ethers (IC50 1 microM), triglycerides (IC50 1.3 microM) and free fatty acids (IC50 2.2 microM). The most pronounced effect of the drugs, i.e. the suppression of the cholesterol ethers synthesis is likely due not only to the ACAT inhibition but also to the inhibition of the triglyceride synthesis and the diminishing of the free fatty acids pool in the cells.     

Ground application of mating disruption against the gypsy moth (Lepidoptera: Erebidae)

The gypsy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is a non‐native defoliating insect that continues to expand its range in North America and undergo periodic outbreaks. In management efforts to suppress outbreaks, slow its spread and eradicate populations that arrive outside of the invaded range, aerial deployments of mating disruption tactics and pesticides are generally used. However, in some cases, such as in heavily urbanized areas or other landscapes where aerial deployments are not feasible or permitted, ground applications are required. Ground applications tend to be labour‐intensive to ensure adequate coverage. To better inform optimal deployment of ground applications of mating disruption, we measured the effectiveness of a pheromone formulation designed for ground application, SPLAT® GM, in forested areas of Virginia from 2011 to 2014 using different dosages and number of point applications. We observed that SPLAT® GM applied to the tree trunks at the dosages of 49.4 and 123.6 g AI/ha in 11 × 11 systematic grids (i.e., every 11 m) reduced male trap catch by >90% relative to untreated control plots, which based on previous studies corresponds to >95% reduction in gypsy moth mating success. Our observations suggest that ground applications of gypsy moth mating disruption can be a successful management tool when circumstances require it.