The chemical-transformation products of 1,6-dibromo-1,6-dideoxygalactitol and 1,2:5,6-dianhydrogalactitol in aqueous solution

After hydrolysis of 1,6-dibromo-1,6-dideoxygalactitol (1) and 1,2:5,6-dianhydrogalactitol (2), 11 compounds were isolated, three of them as tritylated derivatives. Their structures were established on the basis of chemical evidence and, for four compounds, by X-ray diffraction. The main product of the hydrolysis of 1 was 3,6-anhydro-1-bromo-1-deoxy-dl-galactitol; the end-products of the hydrolysis of 2 were 1,5-anhydro-dl-galactitol, 2,5-anhydro-dl-altritol, and galactitol.     

Über die Verteilung epiphytischer Algen auf den Blättern wasserbewohnender Angiospermen sowie systematisch-entwicklungsgeschichtliche Bemerkungen über einige grüne Algen

Ohne Zusammenfassung     

Transplantation of insect giant chromosome nuclei into amphibian oocytes

Polytene salivary gland nuclei of Chironomus pallidivittatus were transplanted into oocytes of Xenopus laevis which were then cultured in vitro for 18 h. The giant chromosomes and nucleoli as well as the entire nuclei enlarged considerably in volume during this time. The polyteny and specific chromomere pattern of the chromosomes were maintained, and the puffing of the salivary gland-specific Balbiani rings was not noticeably changed. — Polytene nuclei from differentiated insect cells transplanted into Xenopus oocytes thus appear suited for exposing giant chromosomes in vivo to purified factors such as regulatory molecules. This paper is dedicated to Professor Wolfgang Beermann on the occasion of his 60th birthday     

The alternating conformation of analogues of poly[d(AT)].

Synthetic DNAs were prepared containing 6-methyl adenine (m6A) in place of adenine and 5-ethyl uracil (Et5U) or 5-methoxymethyl uracil (Mm5U) in place of thymine. All three modifications destabilized duplex DNAs to varying degrees. The binding of ethidium was studied to analogues of poly[d(AT)]. There was no evidence of cooperative binding and the "neighbour exclusion rule" was obeyed in all cases although the binding constant to poly[d(m6AT)] was approximately 6 fold higher than to poly[d(AT)]. 31P NMR spectra were recorded in increasing concentrations of CsF. Poly[d(AEt5U)] showed two well-resolved signals separated by 0.55 ppm in 1 M CsF compared to 0.32 ppm for poly[d(AT)] under identical conditions. In contrast, poly[d(AMm5U)] and poly[d(m6AT)] showed two signals separated by 0.28 ppm and 0.15 ppm respectively, only when the concentration of CsF was raised to 2 M. The signals for poly[d(AT)] in 2 M CsF were better resolved and were separated by 0.41 ppm. These results suggest that minor modifications to the bases may have conformational effects which could be recognized by DNA-binding proteins.     

Ligand-triggered conformational perturbations elicit changes at the single cysteinyl residue of spinach calmodulin

Following application of stoichiometric amounts of Ca2+ or specific partner peptides to spinach calmodulin, dynamic changes in the nanosecond range could be monitored at a strategically anchored fluorescence or spin probe. For these studies the single cysteinyl residue 26 of spinach calmodulin was labelled with a thiol-specific proxyl (i.e. 2,2,5,5-tetramethyl-1-pyrrolidinyl-oxyl) spin probe or with a bimane fluorescence probe. With Ca2+ and a specific ligand (mastoparan) present, fluorescence studies (anisotropy, lifetime) indicated that the rotational motion of the protein complex becomes slower relative to the motion of calmodulin in the absence of the specific ligand. The probe's attachment site 26 appears to reside in a fairly polar microenvironment as reported by a series of proxyl spin probes varying in label length. The rotational correlation time of the shortest spin probe markedly changed upon binding of a specific peptide to a calmodulin region distant from that of the monitoring spin probe. We interpret these observations as indicating that ligand-triggered conformational perturbations are eliciting specific responses at the cysteinyl residue 26 of spinach calmodulin.     

Morphology and biochemical genetics of Atlantic halibut, Hippoglossus hippoglossus (L.), from various spawning grounds

Potential phenotypic/genotypic differentiation of Atlantic halibut, Hippoglossus hippoglossus (L.), samples from two spawning grounds in north Norway (Malangen and Sørøysund) were studied. In addition, the genetic relationship between fish from north Norway, mid–Norway (Folia) and western Greenland (off Fredrikshåb) was investigated. Uni– and multivariate analyses of 15 morphometric measurements and six meristic counts revealed a considerable degree of homogeneity between Malangen and Sørøysund. No morphological characters were thus found suitable as diagnostic tools in the classification of potential halibut stocks. As determined from electrophoretic studies, the allelic distribution at the four polymorphic loci ADA, PGI–2, PGM–2 , and UTP (unidentified tissue protein) did not vary significantly when all four samples (Folia, Malangen, Sørøysund and Greenland) were considered together. However, when the Norwegian coast samples were split into a northern (Sørøysund and Malangen) and a middle (Folla) area, and each locus was regarded isolated, significant heterogeneity was detected at the PGM–2 locus, thus giving evidence for a potential heterogeneity along a north–south axis.     

Phosphate-Activated Glutaminase in the Crude Mitochondrial Fraction (P2 Fraction) from Human Brain Cortex

The kinetics and other properties of phosphate-activated glutaminase have for the first time been studied in the crude mitochondrial fraction (P2 fraction) from human brain. The enzyme is for unexplained reasons inactivated postmortem. The enzyme activity decreases by storing the tissue or homogenate at 37 degrees C. The inactivation is not caused by formation of a dialysable inhibiting compound. No large proteolytic degradation has occurred, since the phosphate-activated glutaminase-like immunoreactive band did not disappear during the storage. The molecular weight of the subunit of the enzyme as determined by immunoblots of sodium dodecyl sulfate-treated homogenates from human brain is estimated to be approximately 64 K. The enzyme has been shown to have a pH optimum of 8.6; it is activated by phosphate, inhibited by glutamate, and partially inhibited by ammonia. Double-inverse plots of enzyme activity against phosphate are concave-upward, and more so in the presence of an inhibitor. The inhibition by glutamate appears to be noncompetitive with the substrate glutamine, and competitive with the activator phosphate. These kinetic properties are not significantly different from our earlier observations concerning phosphate-activated glutaminase from pig brain and pig kidney.     

Evidence for free and metabolically stable p53 protein in nuclear subfractions of simian virus 40-transformed cells.

To determine functional subcellular loci of p53, a cellular protein associated with cellular transformation, we analyzed the nucleoplasmic, chromatin, and nuclear matrix fractions from normal mouse 3T3 cells, from methylcholanthren-transformed mouse (MethA) cells, and from various simian virus 40 (SV40)-transformed cells for the presence of p53. In 3T3 and MethA cells, p53 was present in all nuclear subfractions, suggesting an association of p53 with different structural components of the nucleus. In 3T3 cells, p53 was rapidly turned over, whereas in MethA cells, p53 was metabolically stable. In SV40-transformed cells, p53 complexed to large tumor antigen (large T) was found in the nucleoplasmic and nuclear matrix fractions, as described previously (M. Staufenbiel and W. Deppert, Cell 33:173-181, 1983). In addition, however, metabolically stable p53 not complexed to large T (free p53) was also found in the chromatin and nuclear matrix fractions of these cells. This free p53 did not arise by dissociation of large T-p53 complexes, suggesting that stabilization of p53 in SV40-transformed cells can also occur by means other than formation of a complex with large T.     

Aluminum interaction with calmodulin. Evidence for altered structure and function from optical and enzymatic studies

The interaction of aluminum ions with bovine brain calmodulin has been examined by fluorescence spectroscopy, circular dichroic spectrophotometry and equilibrium dialysis, and by the calmodulin-dependent activation of 3',5'-cyclic nucleotide phosphodiesterase. These experiments show that aluminum binds stoichiometrically and cooperatively to calmodulin. Binding of aluminum at a molar ratio of 2:1 to calmodulin suffices to induce a major structural change. Estimates from spectroscopic data indicate that the binding affinity for the first mol of aluminum bound to the protein is about one order of magnitude stronger than that of calcium to its comparable site. These estimates agree with a dissociation constant of 0.4 microM derived from equilibrium dialysis experiments. Interaction of aluminum with calmodulin induces a helix-coil transition and enhances the hydrophobic surface area much more than calcium does. A molar ratio of 4:1 for [aluminum]/[calmodulin] is sufficient to block completely the activity of the calcium-calmodulin-dependent phosphodiesterase. Highly hydrated aluminum ions apparently promote solvent-rich, disordered polypeptide regions in calmodulin which, in turn, profoundly influence the protein's flexibility.