Occurrence of grapevine chrome mosaic nepovirus in Austria

A virus recovered by inoculation of sap from Austrian vines with yellow mosaic symptoms was compared with, and found virtually indistinguishable from, an authentic Hungarian isolate of grapevine chrome mosaic nepovirus. This seems to be the first record of the virus in Austria.     

Immobilization of urease on gelatin — poly (HEMA) copolymer preparation and characterization

Urease was immobilized onto gelatin-poly (HEMA) copolymer by covalent linkage. Maximum amount of urease was immobilized onto the support at a pH of 8.5. The optimal pH of the immobilized urease was similar to that of free urease; the optimal temperature showed an increase of 10 °C over the free enzyme. The stability of the immobilized urease for a range of pH, temperature and shelf life was greater than the corresponding values for the free enzyme. The same result was obtained for k _m also.Grateful acknowledgement is made to CSIR, Govt. of India for the research associateship conferred on Dr. M. Chellapandian which helped the progress of this piece of research investigation.     

Spatial pattern analysis of the incidence of aster yellows disease in lettuce

The degree of aggregation of lettuce plants infected by aster yellows phytoplasma (AYP) was investigated in 12 fields from three experiments. Position of diseased and healthy plants was mapped in a 6–9×12-m section of each field; for most analyses, fields were divided into 10-plant quadrats. Mean disease incidence (p) ranged from 0.01 to 0.30. The frequency of diseased plants was described by the beta-binomial distribution, with an index of aggregation (θ) ranging from 0 to 0.17, positively correlated withp, and generally increasing over time within a field. Distance-class analysis revealed a core-cluster size of only a few plants. However, spatial autocorrelations ofp between quadrats were not significant, indicating that the scale of spatial pattern was small, generally less than 10 plants. An overall measure of aggregation was given by the slope parameter of the binary form of the power law, in which the log of the calculated variance is regressed on the log of the theoretical variance for a binomial distribution. The slope was 1.18 and significantly different from 1. Results for this “simple-interest” disease are interpreted in relation to the persistent transmission of AYP by its aster leafhopper vector.     

Inhibition of acid production in Streptococcus mutans R9: Inhibition constants and reversibility

Abstract The pac gene encoding the penicillin G acylase (PGA) of Bacillus megaterium ATCC 14945 has been cloned in Escherichia coli HB101 ( proA, leuB ) using a selective minimal medium containing phenylacetyl-L-leucine instead of L-leucine. The nucleotide sequence of this gene has been determined and contains an open reading frame of 2406 nucleotides. The deduced amino acid sequence shows significant similarity with other β-lactam acylases. Although the PGA of B. megaterium is extracellular, the enzyme produced in E. coli appears to have a cytoplasmic localization.     

Reversible beta-pleated sheet formation of a phosphorylated synthetic tau peptide.

Serine416 of human tau protein is believed to be phosphorylated in Alzheimer neurofibrillary tangles. We synthesized a fragment of tau, consisting of amino acids 408-421 in both non-phosphorylated and serine416-phosphorylated forms. Circular dichroism in a trifluoroethanol-water mixture indicated a beta-turn----beta-pleated sheet conformational transition upon phosphorylation. The beta-structure formation is intermolecular and can be inhibited by addition of Ca2+ ions or a phosphorylated tripeptide, but not with its non-phosphorylated analog. The presence of the phosphorylated tau peptide did not facilitate the formation of beta-pleated sheets of a phosphorylated neurofilament fragment. Multivalent cations induced a conformational transition of this phosphorylated neurofilament peptide, but the effect was less specific than the transition induced in the tau fragment, and it could also be reversed with the competing phosphorylated tripeptide.     

Antipeptide antibody to the insulin-like growth factor-I receptor sequence 1232-1246 inhibits the receptor kinase activity.

To approach the question of why insulin-like growth factor-I (IGF-I) and insulin have different physiological actions, we developed antibodies directed against cytoplasmic regions of the IGF-I receptor exhibiting a low degree of homology with the corresponding sequences of the insulin receptor. We found that an antipeptide antibody directed against the beta-subunit carboxyl-terminal sequence (1232-1246) of the IGF-I receptor significantly reduced the in vitro receptor autophosphorylation. The ability of the synthetic peptide corresponding to the IGF-I receptor sequence 1232-1246 to abolish this inhibitory effect reflects the specific nature of the antibody interaction with the targeted domain in the receptor. Antipeptide antibody to IGF-I receptor sequence 1232-1246 also decreased receptor phosphorylation activity toward the exogenous substrate poly(Glu/Tyr). The reduction in poly(Glu/Tyr) phosphorylation was seen even when the antibody was incubated with a receptor previously activated and phosphorylated. Therefore, the inhibitory action on substrate phosphorylation is likely to be unrelated to the antibody reduction of receptor autophosphorylation but rather results from a global decrease in receptor enzymatic activity. The effect of the antipeptide antibody on receptor tyrosine kinase cannot be accounted for by a lowering of the receptor Km for ATP or of its affinity for the substrate poly(Glu/Tyr). Moreover, the interaction of the antibody with the receptor had no repercussion on the ligand binding site as shown by the unaltered IGF-I binding. Taken together our data suggest that the beta-subunit carboxyl-terminal domain of the IGF-I receptor plays a key role in regulating its kinase activity and that the particular sequence recognized by our antipeptide antibody could be involved in negative regulation of receptor functioning.     

Effects of tranquilizing agents on bioelectrical activity of the rat brain]

The action of diazepam, meprobamate, trioxazine and mexidol on bioelectrical activity of sensorimotor cortex and dorsal hippocamp of the left and right hemisphere of the brain in conscious rat in free behavior has been studied. All the drugs produced a decline in the frequency of the dominant peak of EEG power spectra. Diazepam and meprobamate increased beta-activity. It is concluded that the decreased frequency may be due to an anxiolytic effect of the tranquilizers, whereas high beta-activity is related to muscle relaxant effect of some drugs.     

Seasonal and circadian fluctuations in blood biochemical indicators in mice in natural conditions and exposed to constant light]

The fluctuations of activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and those of the levels of protein, glucose, cholesterol, bilirubin, creatinine, blood urea nitrogen, K+, Cl-, Na+ in blood plasma of mice in natural conditions (NC) and exposed to constant light (CL) were studied in different seasons of the year (in January, April, July, October) on days 18, 24, 6 (at 12 o'clock). Most indices both in NC and CL animals had seasonal rhythm similar for each of them. This proves a primary effect of environmental geoclimatic factors of formation of circadian periodicals as compared to desynchronization in constant light revealed by Kosinor analysis in winter (acrophase from 14.16 till 16.32 o'clock) and autumn (acrophase from 23.03 til 4.40 o'clock). During the same seasons one can observe the maximum desynchronization influences of constant light, which leads to abrupt falling (to the 10-fold and more) of the fluctuations amplitude and in some cases to stabilization of circadian rhythm.