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.     

Fructosylation of ergot alkaloids by yeast invertase

Summary A method for transfructosylation of ergot alkaloids elymoclavine, chanoclavine, lysergol, 9, 10-dihydrolysergol using commercial yeast -fructofuranosidase and sucrose is described     

Regeneration of plants from leaf mesophyll protoplasts of the tetraploid potato cultivars Xenia and Bintje

An improved method for the isolation of leaf mesophyll protoplasts ofSolanum tuberosum L. cvs. Xenia and Bintje, their culture and regeneration to plants is described. The improvements involve the culture of nodal stem explants on Schenk and Hildebrandt (SH) medium supplemented with AgNO₃ (7.5 mg 1¹) and Alar 85 (5 mg 1^?1), and the pre-treatment of donor plants for 2–3 weeks at a short photoperiod (6 h), a low irradiance (17 (μmol m^?2s^?1) and a low temperature (20 °C). Regeneration of cell wals was observed within 2–3 d and cell divisions within 7–12 d after resuspending freshly isolated protoplasts in Sidorov et al. (SW) medium. The resulting microcalli were cultured on solid media containing zeatin (1–2,5 mg 1^?1) and/or NAA (0.1 and/or 0.01 mg 1^?1) and subsequently on medium with BAR (0.25 mg1^?1) and GA^?3 (0.1 mg 1¹) for shoot regeneration.     

A new microtitration method for the enumeration of contagious bovine pleuropneumonia (CBPP) vaccines.

A new method is proposed for the microtitration of CBPP vaccines by performing eight parallel endpoint two-fold dilutions. When performed on a 96-well plate, it gives a titre with a precision of +/- 0.2 log10. By comparison, the established method, performed in tubes, gives a precision of only +/- 0.6 log10. The adaptation to microtitre plates allows much more economical culture of larger numbers of samples. Statistical analysis permits determination of vial-to-vial homogeneity of a batch and calculation of a titre with a precision of +/- 0.09 log10. The new method may be applied for the titration of mycoplasmas.     

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.     

Chromosome and nucleotide sequence differentiation in genomes of polyploid Triticum species

Summary The nature of genome change during polyploid evolution was studied by analysing selected species within the tribe Triticeae. The levels of genome changes examined included structural alterations (translocations, inversions), heterochromatinization, and nucleotide sequence change in the rDNA regions. These analyses provided data for evaluating models of genome evolution in polyploids in the genus Triticum, postulated on the basis of chromosome pairing at metaphase I in interspecies hybrids.The significance of structural chromosome alterations with respect to reduced MI chromosome pairing in interspecific hybrids was assayed by determining the incidence of heterozygosity for translocations and paracentric inversions in the A and B genomes of T. timopheevii ssp. araraticum (referred to as T. araraticum) represented by two lines, 1760 and 2541, and T. aestivum cv. Chinese Spring. Line 1760 differed from Chinese Spring by translocations in chromosomes 1A, 3A, 4A, 6A, 7A, 3B, 4B, 7B and possibly 2B. Line 2541 differed from Chinese Spring by translocations in chromosomes 3A, 6A, 6B and possibly 2B. Line 1760 also differed from Chinese Spring by paracentric inversions in arms 1AL and 4AL whereas line 2541 differed by inversions in 1BL and 4AL (not all chromosomes arms were assayed). The incidence of structural changes in the A and B genomes did not coincide with the more extensive differentiation of the B genomes relative to the A genomes as reflected by chromosome pairing studies.To assay changing degrees of heterochromatinization among species of the genus Triticum, all the diploid and polyploid species were C-banded. No general agreement was observed between the amount of heterochromatin and the ability of the respective chromosomes to pair with chromosomes of the ancestral species. Marked changes in the amount of heterochromatin were found to have occurred during the evolution of some of the polyploids.The analysis of the rDNA region provided evidence for rapid fixation of new repeated sequences at two levels, namely, among the 130 bp repeated sequences of the spacer and at the level of the repeated arrays of the 9 kb rDNA units. These occurred both within a given rDNA region and between rDNA regions on nonhomologous chromosomes. The levels of change in the rDNA regions provided good precedent for expecting extensive nucleotide sequence changes associated with differentiation of Triticum genomes and these processes are argued to be the principal cause of genome differentiation as revealed by chromosome pairing studies.