Effect of tubocurarine on the central generator of embryonic spontaneous motility.

The continuous administration of d-tubocurarine (6.5 +/- 0.4 mg/kg e.w./24 h) to chick embryos from the 4th to the 12th day of incubation had a positive effect on defects produced in the development of spontaneous motility either by decentralization of the spinal cord or by chemical phenobarbital depression, or by a combination of both experimental factors. In normal embryos, d-tubocurarine had no effect on the development of spontaneous motility.     

Chromophoric peptide substrates for activity determination of animal aspartic proteinases in the presence of their zymogens: A novel assay

Solid-phase synthesis was used for the preparation of pyroglutamyl-histidyl-p-nitrophenylalanyl-phenylalanyl-alanyl-leucine amide (I) and glycyl-glycyl-histidyl-p-nitrophenylalanyl-phenylalanyl-alanyl-leucine amide (II), two water-soluble and sensitive chromophoric substrates of chicken pepsin, hog pepsin A, and bovine spleen cathepsin D. The kinetic constants of hydrolysis of the p-nitrophenylalanyl-phenylalanyl bond of the substrates were measured by difference spectrophotometry at 308 nm (Δ? = 860 m^?1 cm^?1) and by ninhydrin colorimetry (substrate I, ?₅₇₀ = 2.31 × 10⁴m^?1 cm^?1). The pH optimum of cleavage is 5 for the pepsins and 3.7 for cathepsin D. Since all three proteinases still have a significant activity at pH 5.5–6 a new, simple assay was designed for submicrogram quantities of pepsins in the presence of pepsinogens without interference of the latter. The method is particularly suitable for the analyses of the zymogen activation mixtures.     

Ordovician (Dobrotivá Formation) ostracodes and trilobites from Ejpovice (Bohemia) and their relations to faunas of northern and western Europe

For the first time a complete ostracode and trilobite fauna is described from the Dobrovitá Formation (Ordovician) of Perunica. In contrast to the trilobite fauna the ostracode fauna evidences close relations to both Armorica and Baltica. The trilobite fauna comprises 11 species out of 11 genera, the ostracode fauna comprises 15 (5 new) species out of 15 (1 new) genera.     

Transfer of the broad-host-range IncQ plasmid RSF1010 and other plasmid vectors to the Gram-positive methylotroph Brevibacterium methylicum by electrotransformation

Gram-positive facultative methylotrophic coryneform bacterium Brevibacterium methylicum was efficiently transformed with various plasmids using electroporation of intact cells. In addition to the plasmid vectors pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from coryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasmid pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to be present as autonomous structurally unchanged DNA molecules in B. methylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selective conditions. When plasmid DNAs isolated from B. methylicum were used, the highest efficiency of transformation (10⁵ transformants/g DNA) was achieved. Correspondence to: J. Nevera     

Chemotype pattern differentiation of Thymus pulegioides on different substrates

Relationships between soil chemistry and population chemotype structure of Thymus pulegioides have been studied. The analysis of correlations suggest that an increased carbonate content in soil decreases the chemotype diversity of a population (as calculated by use of the Shannon index): the proportion of linalool chemotype plants rises and that of the phenol chemotype plants declines. In addition, the chemotype diversity decreases with increasing frequency of linalool chemotype, and increases with increase of carvacrol chemotype.     

Direct resolution of ergot alkaloid enantiomers on a novel chiral silica-based stationary phase

A new covalently-bonded, silica-based stationary phase, using as the chiral selector the 1-(3-aminopropyl) derivative of (+)-(5R,8S,10R)-terguride, has been developed to resolve optically active isomers by HPLC. Good resolution of structurally related racemic ergot alkaloids were obtained using water-methanol mixtures as the eluent. Analysis of the influence of the type and concentration of the organic modifier, and the pH of the buffer in the mobile phase allowed the enantioseparation of these compounds to be optimized. Determination of the optical purity of a lisuride-containig drug is reported. © 1994 Wiley-Liss, Inc.     

Pathogenesis of SIVmac251 after atraumatic inoculation of the rectal mucosa in rhesus monkeys

Intrarectal inoculation of rhesus monkeys with low doses of SIV_mac led to a prolonged clinical and virological latency that was not observed for high intrarectal doses or for intravenous inoculation. Animals infected intrarectally with low virus doses remained negative for serum antibody responses to SIV for at least one year even though they readily transferred SIV to naive recipients via transfusion of whole blood.