Indole alkaloids from cell suspension cultures of Rauwolfia serpentina benth

Twelve indole alkaloids belonging to the Ajmaline-, Sarpagine-, Yohimbine-, and Heteroyohimbine-type have been isolated and identified from cell suspension cultures of Rauwolfia serpentina. Ten of the alkaloids were found for the first time in cultured R. serpentina cells. The yield of the main alkaloid vomilenine was 51 times more than that of differentiated plants. Crude enzymes isolated from this cell suspension culture completely metabolize the biogenetic precursor strictosidine under formation of several alkaloidal compounds.     

Biochemical investigation to the reliability of the histochemical demonstration of microsomal arylsulphatase activity in cryostat sections

Summary Polyacrylamide gel-electrophoresis was performed with an extract from cultivated skin fibroblasts. Arylsulphatase activity is measured and visualised using the biochemical substrate dehydroepiandrosterone sulphate and the histochemical substrate 6-bromo-2-naphthyl sulphate respectively. The histochemical substrate was hydrolysed at Rf=0.49 and 0.58 while the biochemical substrate was hydrolysed only at 0.49. We conclude that two different microsomal arylsulphatases exist: a sulphatase able to hydrolyse steroid sulphatases (Rf=0.49) and one unable to hydrolyse steroid sulphatases (Rf=0.58). In consequence it is recommended to carry out an electrophoresis experiment after the histochemical investigation, in order to discriminate between these two types of sulphatase.     

High biological activity of the synthetic replicates of somatostatin-28 and somatostatin-25

We have isolated form extracts of ovine hypothalami two molecules characterized as somatostatin-28 and somatostatin-4-28 (referred to as somatostatin-25). They were reproduced by solid hase synthesis. In equimolar ratio and depending upon the experimental conditions, synthetic somatostatin-28 ans somatostatin-25 are 3-14 times more potent than somatostatin-14 to inhibit the basal in vitro secretion of growth hormone or as stimulated by prostaglandin (PGE2). In early studies in vivo, somatostatin-28 and somatostatin-25 are also more potent than somatostatin-14 in inhibiting the secretion of growth hormone acutely stimulated in the rat by injection of morphine; somatostatin-28 is also longer-acting than somatostatin-14. These results suggest that somatostatin-14, as originally isolated, is a biologically active fragment of a larger molecule of greater specific activity; it should be considered as another form of somatostatin with high biological activity present in some tissues and likely secreted y the tissues along with somatostatin-14 and possibly other somatostatin-peptides of diverse sizes.     

Influence of ashing techniques on the analysis of trace elements in biological samples

Dry ashing and wet ashing are two commonly used methods for the preparation of biological materials for trace element analysis by atomic absorption spectrophotometry. In this paper, National Bureau of Standards (NBS) bovine liver was dry ashed at 450°C for 24 h in silica glass (Vycor) or procelain crucibles; the resulting ash was dissolved in either concentrated nitric or hydrochloric acid. Dry ashing efficiency was evaluated by comparing iron, copper, zinc, and manganese concentrations of the samples with the values certified by NBS. Highest recoveries were obtained by dry ashing in silica glass (Vycor) crucibles. Dissolving the resultant ash in either hydrochloric or nitric acids did not significantly alter the results. A comparison between dry and wet ashing shows the latter method to be superior for the preparation of biological tissues for analysis of iron, copper, zinc, and manganese.     

Substrate effects in tower loop reactors

Summary Hansenula polymorpha was cultivated in a bubble column loop bioreactor employing ethanol and/or glucose as substrates. By varying the substrate concentration, the cultivations were carried out in non-limited, substrate limited and oxygen transfer limited growth ranges. The influence of the transitions from one range to another on reactor performance (OTR,k _L a, a) and cell productivity () were investigated. When employing ethanol as a substrate, the concentration considerably influences the fluid dynamics, mass transfer phenomena and cell productivity. When employing glucose as a substrate, glucose repression occurs. At high glucose concentrations no transition into the oxygen transfer limited growth is possible. The ethanol produced during the glucose repression influences the fluid dynamics, mass transfer phenomena and productivity. With decreasing glucose concentration the glucose repression can be gradually eliminated.     

Foam behaviour of biological media

Summary A simple method was developed for evaluating foam stability. The influence of KCl and MgSO₄ on foam stability of bovine serum albumin foams was investigated. These salts increase foaminess, but diminish foam stability by the same degree. Thus there is little overall.     

Degradation of long chain n-alkanes by Chlorococcales

Summary Four out of thirty-one algae strains belonging to the order Chlorococcales exhibited good growth on solid media containing n-alkanes. Chlorella vulgaris (397) was able to degrade n-tridecane in cooxidation. The corresponding secondary alcohols and ketones in C₂-to C₇-position could be identified in the culture broth. The same oxidation products could be found in the media of cultures grown in darkness with the addition of glucose. This demonstrates a subterminal degradation pathway of C. vulgaris.There was no indication for a mono-or diterminal oxidation of alkanes by algae.The fatty acid pattern of lipids exhibited an incease in long chain acids and a decrease in shorter chain acids. The growth rate of cells grown on alkanes increased after 72 h, but the release of autospores was retarded.