β-carboxyl catalytic effect of N-phosphoryl aspartic acid

The β-carboxylic group in N-dialkylphosphorylated aspartic acid has an activating effect that gives rise to peptides, esters, and ester exchange at the phosphoryl group. In contrast, the γ-carboxylic group of N-alkylphosphorylated glutamic acid has a much smaller effect. Some of the self-activating products were isolated and many model compounds were synthesized to study the novel activating effect of the β-carboxylic group. Mixed anhydride intermediates derived from α-carboxylphosphoryl and β-carboxylphosphoryl groups are proposed for the self-activation mechanism.     

Expression of glucoamylase gene usingSUC2 promoter inSaccharomyces cerevisiae

Summary The cloning of glucoamylase geneSTA using theSUC2 promoter intoSaccharomyces cerevisiae was performed. The signal sequence ofSTA gene was used for the secretion of glucoamylase protein. The plasmid constructed in this way was named YEpSUCSTA and its expression was identified. The expression of YEpSUCSTA was repressed in the presence of glucose in growth medium, but derepressed when glucose became depleted. YEpSUCSTA showed the similar efficiency of glucoamylase secretion as YEpSTA-F which has the entireSTA gene. Glucoamylase activity in starch-glucose medium was largely increased because cell mass and plasmid stability were high in biosynthesis phase compared to extracellular glucoamylase activities in media which starch or glucose was the only carbon source.     

Notes on some African hepatic genera 1–5

The present study deals with five genera of hepatics in Africa, Isotachis Mitt., Anastrophyllum (Spruce) Steph., Tritomaria Schiffn. ex Loeske, Gymnocoleopsis (Schust.) Schust. and Lophozia (Dum.) Dum. All African populations of the genus Isotachis Mitt. are considered to be one species, I. aubertii (Schwaegr.) Mitt. Four species of Anastrophyllum (Spruce) Steph. (s.l.), A. auritum (Lehm.) Steph., A. piligerum (Nees) Spruce, A. subcomplicatum (Lehm. et Lindenb.) Steph. and A. minutum (Schreb.) Schust., and two species of Tritomaria Schiffn. et Loeske, T. camerunensis S. Arnell and T. exsecta (Schrad.) Schiffn. ex Loeske occur in Africa. Gymmocoleopsis multiflora (Steph.) Schust. represents a genus and species hitherto unreported for the African flora. Finally, five Lophozia (Dum.) Dum. species, L. argentina (Steph.) Schust., L. capensis S. Arnell, L. decolorans (Limpr.) Steph., L. hedbergii S. Arnell and L. tristaniana (S. Arnell) Váňa, are reported from central and southern Africa; two of these (L. argentina (Steph.) Schust. and L. decolorans (Limpr.) Steph.) represent the first reports from Africa.     

Pyrus spinosa und ihre Hybriden in Südwestbulgarien

Pyrus spinosa Forsk. (=P. amygdaliformis Will.) kreuzt sich in beträchtlichem Masse mitP. pyraster Burgsd. und mitP. communis L. Es wurden drei Hybriden beschrieben, die zwar weniger, aber gut keimende Samen haben. Potentiell sind in der bulgarischen Population vonP. spinosa Merkmale aller infraspezifischen Taxa vertreten, doch nur zwei von ihnen kommen in grösserem Masse vor, das Vorkommen der weiteren drei ist nur gering. Merkmale des übrigen infraspezifischen Taxon kommen nur in Kombination mit Merkmalen anderer Taxa bei Übergangsformen vor. Vorläufig ist auch die Verbreitung vonP. spinosa und ihrer Hybriden in Bulgarien angegeben.