The mechanisms of amino acids synthesis by high temperature shock-waves

The mechanisms of amino acids syntheses behind high temperature shock-waves were elucidated and distinction was made between the steps occurring in the gas phase and those occurring in solution. In the presence of water vapor, aldehydes and NCN are formed separately in regions of different temperatures along the reacting gas. The aldehydes and ammonia condense to aldimines which add HCN to form α-amino nitriles, all in the gas phase. The hydrolysis to amino acids takes place in solution. In the absence of water vapor, aldimines and NCN are formed in the gas phase but condense to α-amino nitriles only in solution. A fair amount of oxygen only lowers the production of amino acids, which consequently could still be produced in the presence of oxygen in the Earth's primitive atmosphere. The waterless mechanism can operate in the Jovian atmosphere and supply it with ample amounts of amino acids, especially aspartic.     

Thyrotropin induces changes in the morphology and the organization of microfilament structures in cultured thyroid cells

Thyrotropin (TSH) induces morphological changes in cultures of normal rat thyroid cell lines and in primary bovine thyroid cells. It also induces a specific reorganization of the microfilaments of the thyroid cells. Both effects are fully reversible and are mimicked by 8-bromo-cAMP. These results indicate that the trophic response of TSH involves changes in the organization of the actin-containing filaments, probably mediated through cAMP, followed by changes in cell shape.     

Seasonal distribution of airborne pollen in the coastal plain of Israel

Airborne pollen was monitored in three major urban centers of the coastal plain of Israel during the years 1993–1995. Results show spatial and temporal variations among the three sites. Altogether, the number of identified species was rather low. Ornamental trees (Cupressaceae,Pinus, Olea, Casuarina, Ceratonia) and grasses, have constituted the main source of the pollen rain. A substantial contribution of the wild plants of the region was restricted toParietaria, Urtica, Mercurialis, Artemisia, grasses and members of the Chenopodiaceae and Amaranthaceae.     

Mannosylation of glycoproteins and dolichol derivatives in fibroblasts from patients with cystic fibrosis

Increased incorporation of mannose into endogenous glycoprotein fractions has been found in whole cell lysates and crude membrane preparations of cultured skin fibroblasts from patients with cystic fibrosis (1.3–2.3-times normal) when GDP[¹⁴C]mannose served as the mannosyl donor. In contrast, the incorporation of mannose from GDPmannose into lipid fractions containing dolichol phosphate and dolichol pyrophosphate oligosaccharides as well as the incorporation of mannose from dolichol phospho[³H]mannose into both glycoproteins and dolichol derivatives were not significantly different among cell preparations from patients with cystic fibrosis and normal controls. Mannosyltransferase activity toward exogenous glycoproteins as well as the activities of soluble and membranous α-mannosidase and β-mannosidase appeared to be normal and could not account for the observed differences. The altered incorporation of mannose into endogenous glycoprotein may reflect changes in glycosylation processes other than mannosylation.     

Localization of specific antigens ofAzospirillum brasilense Cd in its exopolysaccharide by immuno-gold staining

Elicitation of specific antibodies towardsAzospirillum brasilense Cd was performed by injecting whole, living cells. The antigens which caused this specific response were detected by the immuno-gold technique and found to be located in the exopolysaccharide layer of the bacterial cells.     

A cis-regulatory logic simulator

Background  

A major goal of computational studies of gene regulation is to accurately predict the expression of genes based on the cis-regulatory content of their promoters. The development of computational methods to decode the interactions among cis-regulatory elements has been slow, in part, because it is difficult to know, without extensive experimental validation, whether a particular method identifies the correct cis-regulatory interactions that underlie a given set of expression data. There is an urgent need for test expression data in which the interactions among cis-regulatory sites that produce the data are known. The ability to rapidly generate such data sets would facilitate the development and comparison of computational methods that predict gene expression patterns from promoter sequence.     

Xanthomonas perforans Colonization Influences Salmonella enterica in the Tomato Phyllosphere

Salmonella enterica rarely grows on healthy, undamaged plants, but its persistence is influenced by bacterial plant pathogens. The interactions between S. enterica, Xanthomonas perforans (a tomato bacterial spot pathogen), and tomato were characterized. We observed that virulent X. perforans, which establishes disease by suppressing pathogen-associated molecular pattern (PAMP)-triggered immunity that leads to effector-triggered susceptibility, created a conducive environment for persistence of S. enterica in the tomato phyllosphere, while activation of effector-triggered immunity by avirulent X. perforans resulted in a dramatic reduction in S. enterica populations. S. enterica populations persisted at ∼10 times higher levels in leaves coinoculated with virulent X. perforans than in those where S. enterica was applied alone. In contrast, S. enterica populations were ∼5 times smaller in leaves coinoculated with avirulent X. perforans than in leaves inoculated with S. enterica alone. Coinoculation with virulent X. perforans increased S. enterica aggregate formation; however, S. enterica was not found in mixed aggregates with X. perforans. Increased aggregate formation by S. enterica may serve as the mechanism of persistence on leaves cocolonized by virulent X. perforans. S. enterica association with stomata was altered by X. perforans; however, it did not result in appreciable populations of S. enterica in the apoplast even in the presence of large virulent X. perforans populations. Gene-for-gene resistance against X. perforans successively restricted S. enterica populations. Given the effect of this interaction, breeding for disease-resistant cultivars may be an effective strategy to limit both plant disease and S. enterica populations and, consequently, human illness.     

Avidin-biotin complex incorporation into enzyme-linked immunosorbent assay (ABELISA) for improving the detection ofAzospirillum brasilense Cd

The purpose of this study was to ascertain whether an assay for bacterial lipopolysaccharide (LPS) could be developed based on the specific, stoichiometric binding between Polymyxin B and lipopolysaccharides. Polymyxin B was covalently linked to Sepharose 4B and the LPS-binding capacity of the resulting gel determined by incubation with various amounts of radiolabeled LPS (¹⁴C-LPS) of known specific activity. Competitive binding studies showed an inverse linear relationship between the amount of unlabeled LPS added and the binding of¹⁴C-LPS. The assay enabled the detection of microgram quantities of LPS even though the specific activity of the¹⁴C-LPS used was very low. The study demonstrated the feasibility of a Polymyxin B-based assay for LPS, and possible ways in which the sensitivity of the assay may be increased are discussed.     

Pseudouridine-mediated translation control of mRNA by methionine aminoacyl tRNA synthetase

Modification of nucleotides within an mRNA emerges as a key path for gene expression regulation. Pseudouridine is one of the most common RNA modifications; however, only a few mRNA modifiers have been identified to date, and no one mRNA pseudouridine reader is known. Here, we applied a novel genome-wide approach to identify mRNA regions that are bound by yeast methionine aminoacyl tRNA^Met synthetase (MetRS). We found a clear enrichment to regions that were previously described to contain pseudouridine (Ψ). Follow-up in vitro and in vivo analyses on a prime target (position 1074 within YEF3 mRNA) demonstrated the importance of pseudouridine for MetRS binding. Furthermore, polysomal and protein analyses revealed that Ψ1074 mediates translation. Modification of this site occurs presumably by Pus6, a pseudouridine synthetase known to modify MetRS cognate tRNA. Consistently, the deletion of Pus6 leads to a decrease in MetRS association with both tRNA^Met and YEF3 mRNA. Furthermore, while global protein synthesis decreases in pus6Δ, translation of YEF3 increases. Together, our data imply that Pus6 ‘writes’ modifications on tRNA and mRNA, and both types of RNAs are ‘read’ by MetRS for translation regulation purposes. This represents a novel integrated path for writing and reading modifications on both tRNA and mRNA, which may lead to coordination between global and gene-specific translational responses.