A New Type of Light-Harvesting Complex Detected when Growing Rhodopseudomonas palustris under Low Light Intensity Conditions.

The predominance of the maximum at 800 nm for the light-harvesting complex LH4 (B800) and at 850 nm for LH2 (B800-850) from Rps. palustris is determined by the composition of αß-polypeptides and pigments. In low light (LL) for Rps. palustris, strain KM 286 (1e5), along with LH4, the LL LH2 complex was synthesized with the same absorption at 800 and 850 nm. It differed from the LH4 and LH2 complex, which is synthesized under high illumination, in the composition and content of carotenoids (Car) and bacteriochlorophyll a (BChl a). LH4 differed from LL LH2 and LH2 by an additional emission maximum at 766 nm in the BChl a fluorescence spectra. All three complexes had approximately the same level (about 45%) of the energy transfer efficiency from Car to BChl a. Isolation of LL LH2 complex from Rps. palustris confirms the hypothesis of the synthesis in these bacteria under low light conditions of other types of complexes, except LH4, which is due to the multiple biosynthesis genes of αß-polypeptides and the possibility of their various combinations.

Membrane-Bound Bacteriophytochrome-Like Complex of Phototrophic Purple Non-Sulfur Bacterium Rhodopseudomonas palustris.

A pigment-protein complex of yellow color with absorption maxima at 682 and 776 nm, characteristic for bacteriophytochromes, was isolated from the photosynthetic membranes of the purple bacterium Rhodopseudomonas palustris. Zinc-induced fluorescence of the complex indicated the presence of the biliverdin chromophore covalently bound to the protein. The parameters of low-temperature fluorescence (λ excitation at 680 nm, λ emission at 695 nm) indicated the ability of the complex to undergo photoconversion. These data, as well as the kinetics of accumulation of the red (Pr)-form on far red light, allowed the complex to be classified as a bacteriophytochrome-like complex with its localization in the photosynthetic membranes of Rps. palustris.

Congenital immune defense of the hair.

Studies of two recent decades provided ample data on antibacterial peptides protecting animal and human epithelium of different types; however, no reports about the presence of these compounds in hair keratinocytes appeared up to the present time. Peptides were extracted from specimens of normal intact hair with citric acid solution in 50% ethanol. Antibacterial activity of the resultant extracts was evaluated on Candida albicans test culture by staining and microscopy, by evaluation of growth inhibition zones, and by inoculations. Direct contact with the extract destroyed the greater part of Candida albicans cells up to complete destruction of membranes. Application of the extract to dishes with agar with Candida albicans led in the formation of apparent zones of growth inhibition. The percentage of killed cells increased with prolongation of incubation with the extract. Electrophoresis of hair extract showed bands characteristic of antibacterial peptides RNase, psoriasin, and ß-defensins. Removal of the peptides from the extract by filtration through membrane filter led to loss of its activity. The results indicate that human hair keratinocytes possess congenital antibacterial immunity.

Creation of a new synthetic medium for culturing Helicobacter pylori.

We developed a scheme of consecutive replacement of complex components of a known Brucella medium containing peptones and blood with simple analogs and created a synthetic medium for Helicobacter pylori culturing. H. pylori cells require hemic iron for their growth; an appreciable increment in biomass was ensured by hemoglobin, but not simpler hemocontaining compounds (hemin and cytochrome C). Glutamine (20 g/liter) was used as the main nitrogen-containing component, and other amino acids were added in trace amounts. Adhesion was provided by adding agarose gel (0.1%) also promoting the increase in biomass. The proposed medium of a certain chemical composition differs from the known foreign analogs by the presence of hemocontaining component (hemoglobin), short period of exponential growth, and appreciable accumulation of cell protein.

IgE and IgG antibodies to Malassezia spp. yeast extract in patients with atopic dermatitis.

The presence of immunoglobulins to Malassezia spp. surface proteins in the sera from patients with atopic dermatitis and healthy subjects was studied. It was found that 28% of 25 examined patients with atopic dermatitis had IgE antibodies to Malassezia spp. surface protein preparation. All patients and 5 healthy subjects had IgG antibodies to this preparation. The presence and concentration of specific IgE antibodies in patients with atopic dermatitis correlated with reverse titers of IgG antibodies to this preparation (r=0.782). The medians of values reciprocal to IgG antibody titers in patients with atopic dermatitis with and without specific IgE antibodies to the preparation and in healthy subjects were 64, 1024, and 16, respectively. The preparation derived from Candida albicans (candidine) and previously derived preparation from Malassezia did not cross-react. According to immunoblotting data, the preparation contains allergens presented by proteins with molecular weights 15, 36, 52-56, and 78.4 kDa.

Detection of mutant k-ras sequences in the urine of cancer patients.

DNA fragments from apoptotic cells crossing the renal barrier retain their matrix functions, which allows PCR identification of mutant sequences in excreted DNA. We investigated the possibility of detecting k-ras mutations in urinary DNA of tumor patients (colon cancer). In some patients with k-ras codon 12 mutations in tumor cell DNA the same changes were detected in the urinary DNA. The possibility of using this approach for early diagnosis and monitoring of tumors is discussed.

Genetic analysis of DNA excreted in urine: a new approach for detecting specific genomic DNA sequences from cells dying in an organism.

BACKGROUND: Cell-free DNA from dying cells recently has been discovered in human blood plasma. In experiments performed on animals and humans, we examined whether this cell-free DNA can cross the kidney barrier and be used as a diagnostic tool. METHODS: Mice received subcutaneous injections of either human Raji cells or purified (32)P-labeled DNA. DNA was isolated from urine and analyzed by measurement of radioactivity, agarose gel electrophoresis, and PCR. In humans, the permeability of the kidney barrier to polymeric DNA was assessed by detection in urine of sequences that were different from an organism bulk nuclear DNA. RESULTS: In the experiments on laboratory animals, we found that approximately 0.06% of injected DNA was excreted into urine within 3 days in a polymeric form and that human-specific ALU: sequences that passed through the kidneys could be amplified by PCR. In humans, male-specific sequences could be detected in the urine of females who had been transfused with male blood as well as in DNA isolated from urine of women pregnant with male fetuses. K-ras mutations were detected in the urine of patients with colon adenocarcinomas and pancreatic carcinomas. CONCLUSIONS: The data suggest that the kidney barrier in rodents and humans is permeable to DNA molecules large enough to be analyzed by standard genetic methodologies.

Allergen-containing drug from Malassezia spp. yeast.

Malassezia spp. yeast habituating the skin of healthy humans can be a source of allergens for patients with atopic dermatitis. We proposed a method for obtaining allergen-containing preparation by trimming outer cell wall proteins with 1% sodium dodecyl sulfate. The resultant preparation contained 36 and 67 kD proteins known as Malassezia allergens. IgE antibodies to these proteins were detected in the sera of young people with atopic dermatitis.

4-Hydroxyphenethyl alcohol--a new cytokinin-like substance from the phototrophic purple bacterium Rhodospirillum rubrum 1R.

Three compounds with cytokinin activity have been isolated from the medium of Rhodospirillum rubrum grown photosynthetically. Two N-6 aminopurine cytokinins revealed in the medium were identical with those obtained from R. rubrum cells previously. The third compound with cytokinin activity in Amaranthus caudatus bioassay proved to be a simple phenolic compound with elemental composition C8H10O2. This cytokinin-like substance according to absorption spectra, mass spectrometry and 1H NMR spectra data was identified as 4-hydroxyphenethyl alcohol.

Analysis of human major histocompatibility complex antigens by electrophoretic methods with subsequent immunoblotting.

A fast, simple, and sensitive technique is described for the biochemical analysis of human MHC class I antigens. It is based on 2-D electrophoresis or 1-D isoelectric focusing, followed by immunoblotting. The need for radiolabelling of the cells is eliminated, and because whole cell lysates can be used the number of cells needed for analysis is reduced tenfold over conventional immunoprecipitation techniques. The method can also be used to analyze certain MHC class II antigens.