13C-NMR of double and triple bond carbon atoms of unsaturated fatty acid methyl esters

The carbon magnetic resonance spectra of many fatty acid methyl esters with cis and trans double bonds and triple bonds at various positions and in many different combinations have been investigated.The influence of the ester group on double and triple bonds in the fatty acid chain depends strongly on the positions of these bonds. For a given position the influence is constant, even if one or more other double or triple bonds are present.Together with the evaluated chemical shift parameters for the effects of double and triple bonds on each other, complete assignments are possible and spectra of various types of unsaturated esters can be predicted with high accuracy (±0.1 ppm).     

Effect of rye embryo ribosome nuclease on double-stranded RNA

In extracts obtained by treating rye embryo ribosomes with 0.5 M NH₄Cl, nuclease activity was noted towards double-stranded RNA from virus of Penicillium chrysogenum and towards synthetic poly (A)-poly (U) and poly (I)-poly (C) complexes.     

Effect of dilution rate on growth characteristics of Candida utilis in multistage culture systems with different interstage mixing

The effect of dilution rate on important process parameters of biomass production in two multistage culture systems with different interstage mixing has been examined. Experiments were performed in a multistage tower fermenter and in a cascade of fermenters. Measurements were made at steady-state of continuous culture under constant and identical values of ethanol concentration of 50 gl^?1 in the feed, temperature, OTR and pH in both culture systems used. The microorganism used was Candida utilis. Ethanol inhibition influenced cell growth rate due to the complete dissimilation of the restricted quantity of acetate to H₂O and CO₂, leading to insufficient energy generation. The value of ethanol concentration at which ethanol started to inhibit cell growth was a combined function of OTR, S_R and D. The presence of the interstage mixing resulted in more efficient ethanol conversion to biomass in the whole range of dilution rates and significantly lowered the risk of washing-out at high values of both S_R and D.     

Orientation of pigments and pigment-protein complexes in the green photosynthetic bacterium Prosthecochloris aestuarii

The orientation of pigments and pigment-protein complexes of the green photosynthetic bacterium Prosthecochloris aestuarii was studied by measurement of linear dichroism spectra at 295 and 100 K. Orientation of intact cells and membrane vesicles (Complex I) was obtained by drying on a glass plate. The photochemically active pigment-protein complexes (photosystem-protein complex and reaction center pigment-protein complex) and the antenna bacteriochlorophyll a protein were oriented by pressing a polyacrylamide gel. The data indicate that the near-infrared transitions (Q_y) of bacteriochlorophyll c and most bacteriochlorophyll a molecules have a relatively parallel orientation to the membrane, whereas the Q_y transitions of the bacteriochlorophyll a in the antenna protein are oriented predominantly perpendicularly to the membrane. Carotenoids and the Q_x transitions (590–620 nm) of bacteriochlorophyll a, not belonging to the bacteriochlorophyll a protein, have a relatively perpendicular orientation to the membrane. The absorption and linear dichroism spectra indicate the existence of different pools of bacteriochlorophyll c in the chlorosomes and of carotenoid and bacteriopheophytin c in the cell membrane. The results suggest that the photosystem-protein and reaction center pigment-protein complexes are oriented with their short axes approximately perpendicular to the plane of the membrane. The symmetry axis of the bacteriochlorophyll a protein has an approximately perpendicular orientation.     

Abundance of protein-bound sulfhydryl and bisulfide groups at chromosomal nucleolus organizing regions

Silver stainability of the chromosomal nucleolus organizing regions that contain the structural genes for ribosomal RNA can be abolished by proteolytic and oxidative treatments. Histone extraction has no effect. This indicates that reducing groups of non-histone chromosomal proteins are responsible for silver staining. Treatment with fluorescent sulfhydryl and disulfide specific reagents followed by silver staining demonstrates coincidence of silver dots and brightly fluorescent spots at the short arms of human acrocentric chromosomes where ribosomal RNA-genes are located. After treatment with cupric sulfite reagent in the presence of urea fluorescence and silver staining was no longer possible. Silver staining has been reported to be associated with ribosomal RNA-gene activity. Acrocentric chromosomes that are negative in silver staining also lack the brightly fluorescent spots. Therefore, we conclude that an abundance of protein-bound sulfhydryl and disulfide groups occur at nucleolar organizing regions with active genes. Differentially fluorescing spots could not be observed after staining with fluorescamine. So, either the sulfhydryl reagents used in this study are much more sensitive than fluorescamine to study protein distributions in cytological preparations, or our observations point to a local accumulation of some specific protein(s) rich in sulfhydryls. The presence of many sulfhydryl and disulfide groups at the nucleolus organizing regions seems suggestive of a great flexibility of protein(s) by transition of sulfhydryl groups to disulfide bridges and vice versa at these highly active regions of the genome.     

Neural crest cell migration in relation to extracellular matrix organization in the embryonic axolotl trunk

Temporal and regional aspects of early neural crest cell migration in relation to extracellular matrix (ECM) organization and distribution in the embryonic axolotl trunk were studied by light microscopy, TEM, and SEM. The dominating structure of the interstitial ECM is a complex network of fibrils, which are indicated by ruthenium red staining to consist of collagen in association with ruthenium red-positive components, probably including glycosaminoglycans. The ECM fibrils, which are largely used as substratum for locomotion by the crest cells, have a temporally and regionally specific organization and distribution. Increase in ECM fibrils on the neural tube, ahead of the crest cell front, is correlated with initiation of crest cell emigration, and it is suggested that the fibrils may stimulate this process by providing a suitable substratum for cell locomotion. An increase in ECM fibrils in extracellular spaces surrounding the crest cell population is correlated with an expansion of these spaces and with progressing crest cell migration into them. It is proposed that the spatial organization of the ECM fibrils influences crest cell shape and orientation during early migration.     

Stem growth,flower formation,and endogenous gibberellins in a normal and a dwarf strain of Silene armeria

The physiological basis of dwarfism in a single-gene, recessive mutant of Silene armeria L. was investigated through comparison with a normal strain. Exposure of the normal strain to long days led to stem growth and flower formation while similar exposure of the dwarf strain led only to flowering, with very little stem growth. Application of gibberellin A₃ or A₄₊₇ in short days promoted stem elongation in the normal strain, but had a much lesser effect in the dwarf strain. Upon extraction and chromatographic fractionation of the endogenous gibberellins (GAs) in the normal strain of S. armeria, three zones of GA activity were found. An increase in one zone of activity was found in both strains after 1 long day. Neither the quality nor the quantity of the extractable GAs differed greatly between the dwarf and the normal strain. Vegetative dwarf scions, grafted onto fully induced, normal stocks formed flowers, but their growth habit was not changed. Thus, the lack of stem growth in response to long days in the dwarf strain appears to result from a lack of GA sensitivity in the stem tissue of these plants. However, during flower formation dwarf plants did exhibit elongation of the peduncles. This response was suppressed by the growth retardant 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine-carboxylate methyl chloride (AMO-1618), and applied GA₃ could partially overcome this inhibition. Thus, peduncle elongation in the dwarf strain appears to be regulated by endogenous GAs.Abbreviations AMO-1618 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine-carboxylate methyl chloride - GA(s) gibberellin(s) - LD long day(s) - SD short day(s)     

An H-2 haplotype possibly derived by crossing-over between the (A α A β ) duplex and the E βlocus

The B10.STA62 strain carries the H-2 ^w27 haplotype derived from a wild mouse captured in the vicinity of Ann Arbor, Michigan. Products of two class II loci composing this haplotype, A and A , are serologically, biochemically (by tryptic peptide mapping), and functionally indistinguishable from products controlled by the A ^b and A ^/b genes of the B10.A(5R) strain. In contrast, the polypeptide chain controlled by the third class II locus, E , is different from that controlled by the E ^/b gene. This E ^/w27 chain lacks an antigenic determinant present on the E^b molecule and carries determinants lacking on the E^b molecule, the E ^/b and E ^/w27 peptide maps differ in at least six peptides, and cytotoxic T cells specific for the E ^b chains do not react with B10.STA62 target cells. This great difference between the E ^/b and E ^/w27 chains suggests that the corresponding genes have not been derived from one another by a direct mutational conversion; instead, H-2 ^w27 appears to be a recombinant haplotype derived by crossing-over between the A A duplex and the E locus. This is the first recombinant discovered separating these class II loci.     

A simple mathematical model of the secondary succession of shrubs

A simple simulation model of the secondary shrub succession has been elaborated on the grounds of primary field data from abandoned fields of different ages in the area of Bohemian Karst. The model describes vegetational dynamics using adaptedVolterra-Lotka equations for competing species. Carrying capacities and growth rates are expressed as a function of the depth of the soil.     

Kinetic properties of soluble adenosine triphosphatase of escherichia coli

Summary Bound and solubilized ATPase from Escherichia coli show similar kinetic properties. The saturation curves for MgATP are hyperbolic with both preparations. The straight lines in the Line-weaver–Burk plot indicate that MgATP is the true substrate, that one molecule MgATP is bound per enzyme molecule, and that there is no cooperativity. Presence of EDTA leads to sigmoidal saturation curves. This effect could be reversed by adding MgCl₂ stoichiometrically to EDTA.Different results in other publications, especially in that ofCarreira andMuñoz can be explained as being primarily the consequence of complexing agent contaminations in the assay.