Effect of brassinolide on tyrosine phosphorylation of pea leaf proteins

Brassinosteroid-induced phosphorylation of tyrosine residues in proteins was studied. Proteins of crude extract of pea leaves were analyzed by one- and two-dimensional electrophoresis followed by Western blotting with monoclonal antibodies PY20 to phosphotyrosine proteins. One- and two-dimensional electrophoresis revealed 7 and 13 tyrosine-phosphorylated proteins, respectively. Brassinolide increased the phosphorylation level of most of these proteins. With inhibitors of tyrosine protein phosphatases, such as phenylarsine oxide and orthovanadate, the level of tyrosine phosphorylation of these proteins increased.     

Statistical modeling of biomedical corpora: mining the Caenorhabditis Genetic Center Bibliography for genes related to life span

Background  

The statistical modeling of biomedical corpora could yield integrated, coarse-to-fine views of biological phenomena that complement discoveries made from analysis of molecular sequence and profiling data. Here, the potential of such modeling is demonstrated by examining the 5,225 free-text items in the Caenorhabditis Genetic Center (CGC) Bibliography using techniques from statistical information retrieval. Items in the CGC biomedical text corpus were modeled using the Latent Dirichlet Allocation (LDA) model. LDA is a hierarchical Bayesian model which represents a document as a random mixture over latent topics; each topic is characterized by a distribution over words.     

Effect of 24-epibrassinolide on pea protein tyrosine phosphorylation after salinity action

The effects of the brassinosteroid hormone 24-epibrassinolide (EPB) on growth indices and tyrosine phosphorylation of soluble proteins in pea (Pisum sativum L.) leaves after salinity action were studied. Treatment of plants subjected to salinity (150 mM NaCl for 2 days) with 100 nM EPB for 2 h resulted in the resumed shoot growth. The analysis of phytohormone-induced changes in the tyrosine phosphoproteome after NaCl treatment showed that EPB suppressed tyrosine phosphorylation of proteins functioning in the dark stage of photosynthesis. This is evidently related to the recovery of photosynthetic activity and, as a consequence, of plant growth indices.     

Ring opening of acylated β-d-arabinofuranose 1,2,5-orthobenzoates with nucleophiles allows access to novel selectively-protected arabinofuranose building blocks

β-d-Arabinofuranose 1,2,5-orthobenzoates with 3-O-acetyl, 3-O-benzoyl, and 3-O-chloroacetyl groups were prepared in an efficient manner starting from readily available crystalline methyl 2,3,5-tri-O-benzoyl-α-d-arabinofuranoside, and ring-opening reactions of these compounds with O- and S-nucleophiles were studied. Optimized conditions leading to the formation of the respective monosaccharide adducts (up to 96% isolated yields) and to α-(1→5)-linked disaccharide thioglycosides with 5'-OH unprotected (up to 30% isolated yields) were found. Basing on these results, a novel approach for effective differentiation of 3,5-diol system and 2-hydroxy group in arabinofuranose thioglycosides was proposed. The selectively protected derivatives prepared are valuable building blocks for the assembly of linear and branched oligoarabinofuranosides.     

Ring opening of acylated β-d-arabinofuranose 1,2,5-orthobenzoates with nucleophiles allows access to novel selectively-protected arabinofuranose building blocks

β-d-Arabinofuranose 1,2,5-orthobenzoates with 3-O-acetyl, 3-O-benzoyl, and 3-O-chloroacetyl groups were prepared in an efficient manner starting from readily available crystalline methyl 2,3,5-tri-O-benzoyl-α-d-arabinofuranoside, and ring-opening reactions of these compounds with O- and S-nucleophiles were studied. Optimized conditions leading to the formation of the respective monosaccharide adducts (up to 96% isolated yields) and to α-(1→5)-linked disaccharide thioglycosides with 5′-OH unprotected (up to 30% isolated yields) were found. Basing on these results, a novel approach for effective differentiation of 3,5-diol system and 2-hydroxy group in arabinofuranose thioglycosides was proposed. The selectively protected derivatives prepared are valuable building blocks for the assembly of linear and branched oligoarabinofuranosides.     

Effect of epibrassinolide on tyrosine phosphorylation of the calvin cycle enzymes

Two-dimensional electrophoresis was used to separate proteins from crude extracts of pea (Pisum sativum L.) leaves, and thus isolated proteins were subjected to Western blot analysis with monoclonal antibodies against PY20 phosphotyrosine polypeptides. This analysis revealed 44 polypeptides phosphorylated on tyrosine residues. Phosphorylation of some of these proteins was changed under the action of epibrassinolide. Some of these polypeptides were identified by means of MALDI-TOF MS analysis. The results indicate that eight of these proteins belong to the Calvin cycle enzymes, namely, the isoforms of Rubisco large and small subunits, fructose-1,6-phosphate aldolases 1 and 2, and the precursor of α-subunit of Rubisco-binding protein. The observed changes in phosphorylation of these proteins may partly explain the effects of brassinosteroids on photosynthesis. The tyrosine phosphorylation sites were identified in silico for the fragments of polypeptides examined.     

NaCl induced cross-acclimation to UV-B radiation in four Barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) cultivars

The effect of pre-treatment with 200 mM NaCl on the response of four barley cultivars (Hordeum vulgare L. cv. Bülbül-89, Kalaycı-97, Tarm-92 and Tokak-157/37) to UV-B radiation was investigated. Salt stress as well as UV-B irradiation led to a decrease of the total chlorophyll (chl) content in all cultivars, except in Kalaycı-97. While carotenoids are almost not affected by NaCl treatment, UV-B irradiation caused an increase by 5–20% of carotenoid content of all cultivars. UV-B induced damages of photosynthetic apparatus were estimated by the rate of photosynthetic electron transport measured by chl fluorescence and the rate of oxygen evolution, the latter being more affected. Pre-treatment with NaCl alleviated harmful effect of UV-B irradiation on F _v/F _m and ETR, but not on oxygen evolution. UV-B-induced and UV-B-absorbing compounds with absorption at 300 and 438 nm increased as a result of UV-B treatment. The level of stress marker proline increased considerably as a result of NaCl treatment, while UV-B irradiation resulted in a pronounced increase of the level of H₂O₂. MDA enhanced in the seedlings subjected to salt and UV-B stress. Established cross-acclimation to UV-B as a result of salt treatment could be due to the increased free proline and the level of UV-B absorbing compounds in barley seedlings subjected to NaCl.     

Estimating the rate of evolution of the rate of molecular evolution

A simple model for the evolution of the rate of molecular evolution is presented. With a Bayesian approach, this model can serve as the basis for estimating dates of important evolutionary events even in the absence of the assumption of constant rates among evolutionary lineages. The method can be used in conjunction with any of the widely used models for nucleotide substitution or amino acid replacement. It is illustrated by analyzing a data set of rbcL protein sequences.      

A study of aneurysmal lesions of the aorta using magnetic resonance tomography

Altogether 23 patients with aneurysmal aortic lesions of various sites were investigated using MR-tomography. Sagittal and axial projections were used for visualization of the thoracic aorta, frontal and axial ones--for visualization of the abdominal aorta. As compared to radionuclide and x-ray methods of investigation, MR-tomography was characterized by a high informative value in the detection of aneurysmal lesions. Despite a limited number of patients the authors managed to diagnose aortic stratification which could be well visualized in the abdominal aorta.     

Response of photosynthesis of Pisum sativum to salt stress as affected by methyl jasmonate

10-5 M methyl jasmonate (JA-Me) treatment itself did not considerably change the 14CO2 fixation, parameters of room temperature chlorophyll fluorescence induction, proline content, and Na+ as well as Cl- accumulation. Salt stress (30 mM NaCl) lead to a decrease of both 14CO2 fixation and relative water content, and to an increase of proline content. Immediate nonvariable fluorescence (F0) also increased and the variable to maximal fluorescence ratio (Fv/Fm) decreased. Pretreatment with JA-Me for 3 d before salt treatment diminished the inhibitory effect of NaCl on the rate of 14CO2 fixation, protein content, and activity and content of ribulose-1,5-bisophosphate carboxylase/oxygenase. The Na+ and Cl- contents in leaves decreased in JA-Me pretreated plants. The JA-Me pretreatment prevented the increase of F0 level and restored the values of Fv/Fm.