Second-derivative spectroscopy of proteins: Studies on tyrosyl residues

Ionization of the phenolic group of N-acetyltyrosynamide has been studied using second-derivative spectroscopy. At pH 12.5 the second-derivative spectrum of the model compound revealed the presence of derivative bands in a spectral region (between 250 and 270 nm) where interference coming from other ultraviolet-absorbing chromophores is negligible. One of these peaks (260-nm peak) has been employed for the determination of tyrosyl groups in mixtures containing the aromatic amino acids.     

The structure of Ciliated Protozoa communities in biological sewage-treatment plants

Samples of mixed-liquor from 39 activated-sludge plants and of biological film from 49 rotating discs were examined microscopically for the presence of Ciliated Protozoa. 45 and 47 species of Ciliates were identified in activated-sludge plants and rotating discs, respectively.Most of the ciliate species, which are frequent inhabitants of activated-sludge, were found also in rotating discs. Statistical analysis based on affinity index and on recurrent groups, made it possible to reconstruct the structure in species of ciliate communities both in activated-sludge plants and in rotating discs.     

Adenylat-Pools in Plastiden,Mitochondrien und einer Restzytoplasma-Fraktion,bestimmt unter in vivo-Bedingungen und in Abhängigkeit von Differenzierungsvorgängen

Es wird eine Methode beschrieben, die es ermöglicht, Mesophyllprotoplasten innerhalb von 60 sec in Fraktionen weitgehend unkontaminierter Plastiden, nur schwach durch andere Zellkompartimente verunreinigter Mitochondrien und ein Restzytoplasma zu zerlegen. In Verbindung mit einer weitgehenden Beendigung von Stoffwechselreaktionen ermöglicht diese Technik die Bestimmung von Metaboliten in verschiedenen Zellkompartimenten unter in vivo-Bedingungen. Dies wird gezeigt am Beispiel Plastiden, Mitochondrienund Zytoplasma-assoziierter Adenylatkonzentrationen im Verlauf der Etioplasten-Chloroplasten-Transformation. Die Ergebnisse deuten darauf hin, daß, obwohl kurz nach Beginn der Belichtung in der Zelle vorübergehend stark erhöhte Adenylatkonzentrationen auftreten, die Energieladung 2(ATP)+(ADP)/2([ATP]+[ADP] +[AMP]) der verschiedenen Kompartimente konstant bleibt. Wir danken Dr. S. P. Robinson, H. Wirtz und Prof. R. R. Theimer für wertvolle Anregungen und der Deutschen Forschungsgemeinschaft für finanzielle Unterstützung.     

Isoelectric focusing studies of human pancreatic secretion

Pure bile, pancreatic and duodenal human juices have been analyzed by isoelectric focusing, either at rest or upon stimulation with caerulein. In rats, stimulation has also been performed with secretin. Twenty bands have been resolved and quantified in the pancreatic secretion. By developing zymograms, a number of isozymes have been identified: 6 isoamylases [pI's 7.2, 7.1 and 6.6 (major) and pI's 7.4, 6.7 and 5.8 (minor)], 3 lipases [pI's 7.0 and 6.8 (major) and 6.4 (minor)], two major alkaline proteases (pI's 9.8 and 8.4) and one major acidic protease (pI 4.3) and one band of RNAase activity (pI 8.6). The stimulation kinetics follow a mechanism according to Palade, indicating uniform response to secretogogues, parallel intracellular transport and parallel discharge of pancreatic exocrine proteins.     

Cervical aortic arch with mediocystic necrosis

The case of a 21-year-old woman with symptomatic cervical aortic arch is discussed. Rapid enlargement of an aneurysm at the level of the abnormal arch caused symptoms that prompted the patient to undergo angiographic diagnosis and surgical repair. Histologic examination of the aneurysm revealed mediocystic necrosis, which contributed to the malignant course of the congenital disease. Successful repair was accomplished without the use of cardiopulmonary bypass.     

Gel gradient electrophoresis, isoelectric focusing and two-dimensional techniques in horizontal, ultrathin polyacrylamide layers

An ultrathin layer, horizontal polyacrylamide gel system for electrophoresis, isoelectric focusing and two-dimensional techniques is described. Gel slabs 240 micron thin for unidimensional, or 360 micron thin for two-dimensional runs are cast on cellophane foils as support. The sample is loaded in pockets pre-cast in the gel (2--3 microliter size) or in trenches for two-dimensional experiments. The second dimension is routinely performed in concave exponential gel gradients, spanning an acrylamide concentration from 4% to 22.5%. The sensitivity with the common Coomassie Blue stain is very high, well below 0.1 microgram protein/band. Zymogram detections can be developed within a few minutes, thus retaining the band sharpness of the focused zones or of the bands separated in pore gradient electrophoresis. Sample handling, staining and destaining and gel drying and storage are greatly simplified and performed in a fraction of the time needed for conventional, thick gels in the 1-2 mm thickness range.     

Effect of some organic cosolvents on the reaction of hemoglobin with oxygen

We studied the effects of some organic cosolvents (monohydric alcohols and amides) on the reaction of hemoglobin with oxygen. We present evidence showing that our data can be analyzed within the framework of the Monod-Wyman-Changeux model and that the main effect of cosolvents is to alter the T ? R conformational equilibrium of hemoglobin, without significantly affecting the intrinsic oxygen dissociation constants. Following a previously described phenomenological approach, the overall effects have been separated into effects related to the variation of the bulk dielectric constant of the solvent and effects not related to the variation of this constant.     

Leukemia-cell rejection due to T-region encoded antigens

The role of H-2- and T-region products in determining allogeneic cell rejection was evaluated inH-2 congenic and recombinant mice by transplanting A1ATH and A6ATL leukemia cell lines induced in A.TH and A.TL strains, respectively, by Moloney murine leukemia virus. — InK- orD-region incompatible hosts transplant failure was observed, while inI +T-region incompatible hosts either rejection or prolonged survival was seen. In mice preimmunized with spleen cells fromI- and/orT-region incompatible donors, leukemia cells were rejected by mice immune only to T-region products, and accepted by mice immune only to I-region products. — Cell-mediated cytotoxicity studies confirmed in vivo results. Secondary CTLs specifically directed against I-region products did not lyse the A1ATH and A6ATL cells, and secondary CTLs from A.TH and A.TL mice sensitized against A6ATL and A1ATH cells respectively exerted a lytic action specific for T-region products, while no activity was observed against I determinants. — The data suggest that tumor-transplant rejection may also be governed by histocompatibility antigens encoded in theT region.     

On a mathematical procedure for detecting significant parameters in the classification of a statistical ensemble of phenomena and its applications

Summary The paper is concerned with a procedure for detecting the uncorrelated linear combinations of a given set of random variables. The linear transformation which is used is related to the eigenvectors of the covariance matrix for the original random variables. If the significant non correlated signals are in number less than the original ones (which have often a high degree of redundancy) the possibility arises for an application of this procedure to some branches of communication theory. The most important applications should be to vocoder for a further compression of information, for masking messages and also for building a machine which should be able to classify a statistical ensemble after suitable coding. The procedure has been tested by trying to extract significant parameters from a special coding of spoken Italian vowels in view of an improvement in the efficiency of speech recognition.