13C NMR investigation of the anomeric specificity of CMP-N-acetylneuraminic acid synthetase from Escherichia coli.

The anomeric specificity of Escherichia coli CMP-N-acetylneuraminic acid (CMP-NeuAc) synthetase was investigated by NMR using 13C-labeled N-acetylneuraminic acid (NeuAc). Consumption of the beta-anomer of [2-13C]N-acetylneuraminic acid was observed upon addition of enzyme, with a concomitant appearance of an anomeric resonance for CMP-N-acetylneuraminic acid. Inhibition by substrate analogues the anomeric oxygen was determined in a similar manner using [2-13C,(50 atom %)18O]N-acetylneuraminic acid. An upfield shift of 1.5 Hz in the anomeric resonance of both the [13C]NeuAc substrate and CMP-[13C]NeuAc product was observed due to the 18O substitution. This result implies conservation of the NeuAc oxygen. Results of steady-state kinetic analysis suggest a sequential-type mechanism and therefore no covalent intermediate. Thus, CMP-beta-NeuAc is probably formed by a direct transfer of the anomeric oxygen of beta-NeuAc to the alpha-phosphate of CTP.     

Brief International Cognitive Assessment for MS (BICAMS): international standards for validation

ABSTRACT: An international expert consensus committee recently recommended a brief battery of tests for cognitive evaluation in multiple sclerosis. The Brief International Cognitive Assessment for MS (BICAMS) battery includes tests of mental processing speed and memory. Recognizing that resources for validation will vary internationally, the committee identified validation priorities, to facilitate international acceptance of BICAMS. Practical matters pertaining to implementation across different languages and countries were discussed. Five steps to achieve optimal psychometric validation were proposed. In Step 1, test stimuli should be standardized for the target culture or language under consideration. In Step 2, examiner instructions must be standardized and translated, including all information from manuals necessary for administration and interpretation. In Step 3, samples of at least 65 healthy persons should be studied for normalization, matched to patients on demographics such as age, gender and education. The objective of Step 4 is test-retest reliability, which can be investigated in a small sample of MS and/or healthy volunteers over 1-3 weeks. Finally, in Step 5, criterion validity should be established by comparing MS and healthy controls. At this time, preliminary studies are underway in a number of countries as we move forward with this international assessment tool for cognition in MS.     

Identification of microspore-derived plants in anther culture of flax (Linum usitatissimum L.) using molecular markers

The microspore origin of anther-culture-derived plants of flax was determined using inter-simple sequence repeat (ISSR) and randomly amplified polymorphic DNA (RAPD) markers. Polymorphic fragments between the two parents of the F₁ donor plants were identified and their segregation patterns in anther-culture-derived plants were used to elucidate the origin of those plants and to determine the degree of independence of plants regenerated from the same callus. Using one ISSR primer (UBC 889) and two RAPD primers (UBC 556 and 561), 12 out of 16 plants were unequivocally identified as being derived from microspores. Plants derived from the same callus had identical PCR patterns at five polymorphic loci and thus were likely derived from the same microspore. Therefore, it is proposed that the number of calli forming shoots be used to describe the anther culture efficiency in flax. Received: 3 February 1998 / Revision received: 8 June 1998 / Accepted: 8 July 1998     

Die züchterische Bearbeitung des Kulturchampignons (Psalliota bispora Lge.) Probleme und erste eigene Ergebnisse

Ohne ZusammenfassungMit 9 AbbildungenHerrn Prof. Dr.Hans Stubbe zum 60. Geburtstag gewidmet.