A Reexamination of Correlations of Amino Acids with Particular Secondary Structures

Using the data from Protein Data Bank the correlations of primary and secondary structures of proteins were analyzed. The correlation values of the amino acids and the eight secondary structure types were calculated, where the position of the amino acid and the position in sequence with the particular secondary structure differ at most 25. The diagrams describing these results indicate that correlations are significant at distances between −9 and 10. The results show that the substituents on Cβ or Cγ atoms of amino acid play major role in their preference for particular secondary structure at the same position in the sequence, while the polarity of amino acid has significant influence on α-helices and strands at some distance in the sequence. The diagrams corresponding to polar amino acids are noticeably asymmetric. The diagrams point out the exchangeability of residues in the proteins; the amino acids with similar diagrams have similar local folding requirements. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Different susceptibility of prefrontal cortex and hippocampus to oxidative stress following chronic social isolation stress

Chronic oxidative stress plays an important role in depression. The aim of present study was to examine the stress-induced changes in serum corticosterone (CORT) levels, cytosolic protein carbonyl groups, malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO) and total superoxide dismutase (SOD) activity in the prefrontal cortex versus hippocampus of male Wistar rats exposed to acute (2 h of immobilization or cold), chronic (21d of social isolation) stress, and their combination (chronic + acute stress). The subcellular distribution of nuclear factor-κB (NF-κB) and cytosolic cyclooxygenase 2 (COX-2) protein expressions were also examined. Depressive- and anxiety-like behaviors were assessed via the forced swim, sucrose preference, and marble burying tests in chronically isolated rats. Although both acute stressors resulted in elevated CORT, increased MDA in the prefrontal cortex and NF-κB activation accompanied by increased NO in the hippocampus were detected only following acute cold stress. Chronic isolation resulted in no change in CORT levels, but disabled appropriate response to novel acute stress and led to depressive- and anxiety-like behaviors. Increased oxidative/nitrosative stress markers, likely by NF-κB nuclear translocation and concomitant COX-2 upregulation, associated with decreased SOD activity and GSH levels, suggested the existence of oxidative stress in the prefrontal cortex. In contrast, hippocampus was less susceptible to oxidative damage showing only increase in protein carbonyl groups and depleted GSH. Taken together, the prefrontal cortex seems to be more sensitive to oxidative stress than the hippocampus following chronic isolation stress, which may be relevant for further research related to stress-induced depressive-like behavior.     

Diarylheptanoids from Green Alder Bark and Their Potential for DNA Protection

Nine diarylheptanoids, 1 – 9 , catechin ( 11 ), and a phenolic glucoside, 10 , were isolated from the bark of green alder (Alnus viridis). Four of the isolated compounds, i.e., 2, 5, 8, 10 , are new. The structures of 1 – 11 were determined on the basis of spectroscopic data. All isolated compounds were evaluated for their in vitro protective effects on chromosome aberrations in peripheral human lymphocytes using cytokinesis‐block micronucleus (CBMN) assay. Almost all of them exerted a pronounced effect of decreasing DNA damage of human lymphocytes, acting stronger than the known synthetic protector amifostine.     

Impact of abscisic acid in overcoming the problem of albinism in horse chestnut androgenic embryos

Horse chestnut (Aesculus hyppocastanum L., Hyppocastanacea) is a relict species with a slow and complex reproductive cycle considered to have horticultural and medical importance. The cycle maybe circumvented via in vitro androgenesis. Androgenesis of horse chestnut was induced in microspores and anther culture on MS media. Some of the horse chestnut androgenic embryos were albinos. Addition of abscisic acid in media (in concentrations of 0.01, 0.1, 0.5, 1, 2, 5, 10, and 20 mg l^?1) with horse chestnut androgenic embryos has circumvented the reproduction cycle barriers. The best results were achieved on medium with the lowest abscisic acid concentration (0.01 mg l^?1) in microspore culture. The microspore culture proved to be a better model system for embryo production and albino embryo reduction than anther culture. Flow cytometry analysis after maturation treatments induced by ABA showed that 88 % of green embryos originating from microspore culture were haploid. However, 50 % of green embryos from anther culture were haploid. The remaining analyzed androgenic embryos, from both types of cultures were diploid.     

Urban Development Consequences on the Wetland Ecosystems Transformations—Case Study: Pančevački Rit,Serbia

The article analyzes the consequences of one century long human influences on vegetation of the wetland ecosystem, on the example of Pan?eva?ki Rit in Belgrade, Serbia. The autochthonous, non-altered ecosystem was formed in the alluvial plain between Danube and Timis River in the formation of connected swamps and bogs with periodically flooded patches. The major transformation of the wetland ecosystem started with the construction of the embankment and dense canal system followed by settlements development, increasing of population density, intensification of agriculture activities etc. The study area transformation factors were identified in the first phase of research, while the second phase includes analyses of their influences on habitat conversion using GIS, with the purpose to preserve fragments of indigenous wetland vegetation, mostly fragile wetland meadows from further degradation.     

Chemotaxonomic Approach to the Central Balkan Sedum Species Based on Distribution of Triterpenoids in Their Epicuticular Waxes

Triterpenoid distribution in epicuticular waxes of 20 central Balkan Sedum L. species and four out‐groups of genera: Hylotelephium H. Ohba , Crassula L., Echeveria DC., and Kalanchoe Adans . were investigated for chemotaxonomic purposes. Identification and quantification of wax triterpenoids were performed by GC/MS and GC‐FID analyses. Distribution of identified triterpenoids (oleanane, lupane, and taraxerane series), as a pattern in statistical analysis, indicated very good agreement with phylogeny and systematics, except members of series Rupestria Berger , in which case the distribution of triterpenoids did not support known classification in a satisfactory manner. According to the obtained clustering, Kalanchoe is shown as similar to Sedum samples, while the other out‐groups were clearly separated.     

Gibberellins and light synergistically promote somatic embryogenesis from the in vitro apical root sections of spinach

Plant Cell, Tissue and Organ Culture (PCTOC) - Gibberellins (GAs) play a pivotal role in the induction of somatic embryogenesis from in vitro root apices of spinach plants. With the aim to...     

Contribution of inorganic cations and organic compounds to osmotic adjustment in root cultures of two <Emphasis Type="Italic">Centaurium</Emphasis> species differing in tolerance to salt stress

The effect of reduced availability of sugars on growth and essential metabolic processes in roots, resulting from decreased photosynthesis under salinity, was excluded by establishing a non-photosynthetic model-system in this study: root cultures of Centaurium maritimum (L.) Fritch and Centaurium spicatum (L.) Fritch. The contribution of inorganic cations and organic compounds (e.g. carbohydrates and amino acids) to the osmotic adjustment (OA) in roots during short-term exposure to various salt concentrations (0, 50, 100 or 200 mM NaCl) was emphasized. Observed morphological and histological changes in roots were species specific, and were dependent on salinity level. Although C. spicatum appears to be more tolerant to salt stress, both species employed similar strategies in response to elevated salinity to different extents, and displayed effective OA mechanisms. Under low and moderate salinity, inorganic cations were the major contributors to OA in roots of both species, followed by soluble sugars, while the relative contribution of proline (Pro) and free amino acids was insignificant. Osmotic adjustment under severe stress appears to be mediated by increased accumulation of organic compounds. The analysis of the intraspecies variability in salt response of C. spicatum and C. maritimum roots enabled the identification of some organic compounds which could be used as potential biochemical markers in screening for salt tolerance, including Pro in C. spicatum, and trehalose and polyols in C. maritimum.