Bakterien,Pilze und Algen: ein neuer Typ von Kulturpflanzen

Genetic Resources and Crop Evolution -     

Über Wurzel-Sproß-Beziehungen

Ohne ZusammenfassungVorgetragen im Gaterslebener Colloquium am 15. 11. 1952. Meinem Lehrer, Herrn Oberstudiendirektor a. D. Rudolf Gräf, zum 65. Geburtstag gewidmet.     

Phosphorylation of the 12S globulin from rapeseed (Brassica napus L.) by phosphorous oxychloride: chemical and conformational aspects

The effect of progressive phosphorylation by phosphorous oxychloride upon the conformation of the 300 kDa storage protein (cruciferin) from rapeseed has been studied using chemical analysis, SDS-PAGE, HPLC, analytical ultracentrifugation, viscometry, fluorescence spectroscopy, and hydrophobicity measurement. The amount of phosphorous in the protein increased with the excess of phosphorous oxychloride and the pH of reaction. The bulk of phosphorus was only loosely bound to the protein and was removed by washing with cold perchloric acid. The more stably bound phosphorus groups after reaction at pH 8 were found to be nearly equally attached to amino and hydroxyl groups, whereas phosphorylation at pH 10-11 led to predominant O-phosphorylation as detected by studying the acid- and alkali-lability of the protein-phosphorous bonds. A 50 kDa component appeared as a product of covalent cross-linking of the constituent alpha- and beta-polypeptide chains. A 2.5S fraction appeared as the main product of dissociation, which takes place after a critical step of modification. The higher the extent of phosphorylation, the larger was the percentage of higher molecular weight products, the percentage of which was most significant after modification under strongly alkaline conditions. They may be attributed both to products of chemical cross-linking and to noncovalently linked aggregates formed by interactions of partially unfolded derivatives exhibiting an increased surface hydrophobicity.     

Specificity analysis of anti-gliadin mouse monoclonal antibodies used for detection of gliadin in food for gluten-free diet

A gluten-free diet (GFD) is the sole effective long-lasting treatment of celiac disease. Four monoclonal antibodies (Abs) were prepared by immunization of animals kept on GFD with gliadin. The specificity of these Abs to decapeptides of alpha- and gamma-gliadin and omega-secalin was analyzed by the PEPSCAN technique. Repetitive sequences of alpha- and gamma-gliadin and omega-secalin containing the motifs QPFPXQ (X = Q, L, P) were recognized by all Abs tested. These Abs also frequently reacted with peptides containing the sequences QQSFPQQ, QQTFPQP, and QPFRPQ. On the basis of PEPSCAN results two Abs--8D4 and 7C6--were selected for the construction of a new ELISA kit for the detection of gliadin in food. The comparison of data obtained using the newly developed ELISA kit and commercially available ones indicated that Abs selection on the basis of their fine specificity to gliadin is useful for sensitive detection of gliadin in foods.     

Action of the microbial metabolite and chitin synthesis inhibitor nikkomycin on the mite Tetranychus urticae; an electron microscope study

Chitinous structures of Tetranychus urticae K., after treatment with the microbial metabolite nikkomycin, were examined using an electron microscope. The results were compared with published information on the mechanisms of action of this antibiotic. Application of the drug resulted in an inhibition of moulting, due to a deficient or abnormal differentiation of the procuticle during ecdysis. Damage to the procuticle caused disorders in the muscle attachments, preventing the chrysalis stages leaving their exuviae after treatment with the metabolite. Application of nikkomycin to an adult female caused plug-like accumulations below the procuticle of the prosoma and cranial opisthosoma, as well as inside the hypodermis. The egg shell was another site of action of nikkomycin; depending on when drug treatment began, an abnormally thickened or incomplete plaque-like egg shell was produced. The deposition of affected eggs was strongly inhibited, if they were laid at all. The electron micrographs supported the suggestion that a competitive inhibition of chitin synthetase results in inhibition of cuticle synthesis. However, such a mechanism of action cannot explain the results on egg shell damage after nikkomycin treatment, which indicates some other influences of the antibiotic.     

Towards a new gliadin reference material–isolation and characterisation

Twenty-eight wheat cultivars representative of the three main European wheat producing countries, France, UK and Germany, were selected as a source for the preparation of a reference gliadin. One kilogram of kernels from each cultivar were mixed and milled. The resulting white flour was defatted and vacuum dried. Albumins and globulins were eliminated by extraction using 0.4 M NaCl solution and gliadins were extracted with 60% ethanol. The gliadin extracts were concentrated, desalted by ultrafiltration, freeze-dried, and homogenised. After tests had shown good solubility and homogeneity, aliquots of the reference gliadin were sent to 16 different laboratories for further investigations: The material was analysed by various methods including RP-HPLC, SE-HPLC, RP-HPLC-ESI-MS, MALDI-TOF, capillary electrophoresis, acid-PAGE, 2D-PAGE, SDS-PAGE and immunoblotting and ELISA-tests with different monoclonal and polyclonal antibodies. The results showed that the gliadin composition of the source flour and the reference gliadin matched perfectly, demonstrating that no major gliadin components had been lost during the isolation procedure. The reference gliadin showed good immunochemical sensitivity with different gliadin antibodies in enzyme immunoassays. Because of its high protein and gliadin content, good solubility, homogeneity, stability and representative character, the product is regarded as a suitable universal reference material.