Infrared Spectroscopic Study of the Secondary Structure of Wheat,Rye, and Barley Prolamins

The secondary structure of prolamins, the storage proteins of wheat (Triticum aestivum L.), rye (Secale cereale L.), and barley (Hordeum vulgare L.), was studied by infrared (IR) spectroscopy. The secondary structure of wheat gliadin was characterized by a high content of unordered conformations of polypeptide chains (64–67%) and a low content of short -helical regions (4–5%). Elongated conformations, formed by poly-L-proline II helices (61 and 53%) and -turns (15 and 19%), predominated in rye secalins and barley hordeins. Prolamin proteins of cereal crops also contained -sheet structure regions comprising 9–12% of the polypeptide chains.     

The structure of plant vacuolar membranes according to infrared spectroscopy

The structure of the vacuolar membrane (tonoplast) was studied in red beet roots by IR spectroscopy. The vacuolar membrane was shown to be composed of highly ordered lipids which form regions of free liquid lipid bilayer loosely bound to integral proteins. The prevalence of polar lipids in the tonoplast is responsible for the high elasticity and fluidity of the membrane. The presence of alpha-tocopherol in the tonoplast membrane accounts for a high antioxidant activity of the membrane. Integral proteins are immersed into the liquid matrix of the lipid bilayer to a different extent. Examination of the temperature effect on the kinetics of the hydrogen-deuterium exchange in integral membrane proteins showed that the efficient energy of the hydrogen exchange activation was 24 +/- 4 kcal/mol at 19-40 degrees C and increased to 54 kcal/mol at 40-50 degrees C because of the thermal denaturation of proteins. The secondary structure of integral membrane proteins is characterized by a high content of alpha-helices (53%) which decreased to 8% after the extraction of lipids.     

Specific glycanforms of type IX collagen accumulate in embryonic chick sterna after 17 days of development

Type IX collagen is a key component of the extracellular matrix of cartilage where it occurs at the surfaces of type II collagen fibrils as a glycanated molecule. The function of the glycosaminoglycan (GAG) side chain of the molecule is, however, unknown. We have shown that type IX collagen in chicken sternal cartilage is synthesized with a unimodal distribution of GAG chain size, but at post 17 days of development three predominant glycanforms of type IX collagen accumulate. Such accumulation did not occur in sterna from day 15 embryos. In day 17 embryos predominant glycanforms were found in the caudal region of the sternum. By day 19 of development the three predominant glycanforms are widespread throughout the caudal and cephalic regions. The results indicate that developmental and anatomical changes occur to type IX collagen that depend on the size of the GAG chain attached to the alpha2(IX) chain of the molecule.      

HIV infection in Saint Petersburg: the changing face of the epidemic

The specific features of the epidemiological situation in St. Petersburg at the first stage (1987-1995) and the second stage (1986-1999) of the development of HIV infection are described. During this period morbidity in HIV infection, starting from the insignificant rate of growth, sharply increased. For the first time injecting drug users were noted to come out to the foreground in the structure of the contingent of persons affected by HIV infection (57.5% and 72.6% in 1998 and 1999 respectively). Such change on the epidemic situation requires corrections in the strategy and tactics of preventive measures and medical assistance. To control HIV infection among drug users, only the combination of medical assistance given by narcologists with the realization of all elements of the program "Harm Reduction" can be effective.     

Characteristics of fatty acid composition of lipids in higher plant vacuolar membranes

The fatty acid composition of vacuolar membrane lipids from plant storage tissues and their genesis have been studied. A high content of unsaturated fatty acids (up to 77%) was observed in lipids of these membranes. Linoleic acid prevailed in vacuolar lipids of carrot and red beet (54.2 and 44.2%, respectively). Linolenic acid prevailed in vacuolar lipids of garden radish and turnip (39.7 and 33.9%, respectively). Regarding saturated fatty acids, vacuolar lipids of garden radish, carrot, and red beet contained predominantly palmitic acid (up to 20-24%). Unsaturated fatty acids, petroselinic (C18: 1omega12), cis-vaccenic (C18: 1omega7), hexatrien-7,-10,-13-oic (C16:3omega3) and others, were observed in vacuolar lipids of roots. These acids are usually synthesized in chloroplasts, and their presence in vacuolar lipids can be associated either with the transport of metabolites to the vacuole, or with endocytosis during vacuolar formation in the plant cell. The specific features of fatty acid composition of tonoplast lipids apparently are closely related to the tonoplast unique fluidity and mobility required for running osmotic processes in the cell and for forming transport protein assemblies.     

Effect of adement preparation and its low-molecular fractions on development of neurodegenerative processes in Drosophila melanogaster mutants

Neuroprotective and neuroactivative properties of Adement preparations and the influence of Adement and its low-molecular fractions (9-10 Da, 4-6 Da, 1-2 Da) on dinamics of neurodegenerations, viability and lifetime of Drosophila melanogaster mutants with changes of brain structures have been investigated. It was shown that Adement as neuroprotector causes the delay of neurodegenerative changes by 10-15 days and increase of lifetime by 14%. None of the studied low-molecular fractions did not reveal the better effect on these indices than the total preparation. The use of Adement as neuroactivating agent in the complex with other preparations (neuroprotective agent + neuroactivating agent + neuroretardant) is more effective as the development of neurodegenerative changes in mutant brain stops for 20-27 days depending on genotype and a mean lifetime increases by 10-33%.     

Arabidopsis ATG4 cysteine proteases specificity toward ATG8 substrates

Macroautophagy (hereafter autophagy) is a regulated intracellular process during which cytoplasmic cargo engulfed by double-membrane autophagosomes is delivered to the vacuole or lysosome for degradation and recycling. Atg8 that is conjugated to phosphatidylethanolamine (PE) during autophagy plays an important role not only in autophagosome biogenesis but also in cargo recruitment. Conjugation of PE to Atg8 requires processing of the C-terminal conserved glycine residue in Atg8 by the Atg4 cysteine protease. The Arabidopsis plant genome contains 9 Atg8 (AtATG8a to AtATG8i) and 2 Atg4 (AtATG4a and AtATG4b) family members. To understand AtATG4’s specificity toward different AtATG8 substrates, we generated a unique synthetic substrate C-AtATG8-ShR (citrine-AtATG8-Renilla luciferase SuperhRLUC). In vitro analyses indicated that AtATG4a is catalytically more active and has broad AtATG8 substrate specificity compared with AtATG4b. Arabidopsis transgenic plants expressing the synthetic substrate C-AtAtg8a-ShR is efficiently processed by endogenous AtATG4s and targeted to the vacuole during nitrogen starvation. These results indicate that the synthetic substrate mimics endogenous AtATG8, and its processing can be monitored in vivo by a bioluminescence resonance energy transfer (BRET) assay. The synthetic Atg8 substrates provide an easy and versatile method to study plant autophagy during different biological processes.     

Diversity and ecology of algae from the Nahal Qishon river,northern Israel

In 59 samples of periphyton and phytoplankton collected in 2002 - 2003 from the Nahal Qishon (Qishon River), northern Israel, we found 178 species from seven divisions of algae and cyanoprocaryotes. Diatoms, clorophytes, and cyanoprocaryotes prevail. Nitzschia and Navicula (Bacillariophyta) are the most abundant. Most of the species are cosmopolitan or widespread, except Lagynion janei (Chrysophyta), which is endemic for the Mediterranean Realm. About 17% of species (26) are new for Israel and five of them represent the first recorded genera: Crinalium endophyticum Crow, Actinocyclus normanii (Gregory) Hustedt, Rhizoclonium hieroglyphicum (Agardh) Kütz (Chlorophyta), Lagynion janei Bourelly, and Stylococcus aureus Chodat. Most of them come from a rare riverine assemblage with red alga Audouinella pygmea, as well as from the estuarine assemblage. Alkaliphiles predominate among the indicators of acidity, with few acidophiles confined to the communities under the impact of industrial wastes. Among the indicators of salinity, most numerous are the oligohalobien-indifferents and species adapted to a moderate salinity level. The relative species richness of ecological groups and the indices of saprobity are correlated with changes in conductivity, pH, and N-nitrate concentration. Indicators of organic pollution fall in the range of betameso- to alfamesosaprobic self-purification grades. Our studies show ecological significance of the Nahal Qishon as a model for a strongly disturbed aquatic ecosystem in the coastal zone of eastern Mediterranean.