N2-fixation in Erwinia herbicola

Four from 18 strains of Erwinia herbicola tested had nitrogenase activity and grew with N₂ as sole source of nitrogen under strict anaerobic conditions with a doubling time of 20–24 h. Nitrogenase activity started only 96–120 h after transfer to a special medium maintained under anaerobic conditions. A ten fold increase in protein per culture found after the maximum nitrogenase activity of 80–130 nmol C₂H₄. mg protein^-1·min^-1 was accompanied by a fall in pH of the medium (20 mM phosphate buffer and in 125 mM Tris-buffer) from pH 7.2 to 5.4 or less, but only to 6.8 in 100 mM phosphate buffer. In all cases we found a sharp curtailing of nitrogenase activity 48 h after the maximum. The bacteria utilized only 35–50% of the nitrogen fixed for growth. Erwinia herbicola strains differed from two strains of Enterobacter agglomerans in being unable to fix nitrogen on agar surfaces exposed to air. Specific nitrogenase activity in Erwinia herbicola is compared with data reported for other Enterobacteriaceae and is found to be higher than that reported for Klebsiella pneumoniae, Enterobacter cloacae or Citrobacter freundii.     

Biphasic nitrogenase activity in Azospirillum brasilense in long lasting batch cultures

Long lasting batch cultures of Azospirillum brasilense SP 7 ATCC 29145 grown in liquid malate medium for 8–14 days without any fixed nitrogen source exhibited a biphasic nitrogenase activity, when incubated under gas atmospheres of 99.0% N₂ and 1.0% O₂ or 99.5% N₂ and 0.5% O₂ respectively. Maximum specific nitrogenase activity was 1100 nmol C₂H₄·mg protein^-1·h^-1. Poly-3-hydroxybutanoic acid (PHBA) synthesis and growth of the cells also showed two phases. Maxima and minima of glutamine synthetase activity developed synchronously with nitrogenase activity, whereas those of glutamate dehydrogenase and alanine aminotransferase were reverse. During a 192 h period of growth protein increased 3–4-fold and PHBA 25 fold. At maximum accumulation of the polymer the PHBA-nitrogen ratio was 6:1 or 8:1. Azospirillum brasilense was also able to fix nitrogen on agar surfaces exposed to air, but nitrogen fixation was monophasic under these conditions during a 14 d period. Specific nitrogenase activity was dependent on the type and concentration of the source of fixed nitrogen (leucine, ammonia) in solidified media. With 1 mM leucine maximum specific nitrogenase activity was 110 nmol C₂H₄·mg protein^-1·h^-1.Non-Standard Abbreviations PHBA poly-3-hydroxybutanoic acid - TAPS tris(hydroxymethyl)methylaminopropane sulfonic acid - TES N-tris(hydroxymethyl)methyl-2-aminoethane sulfonic acid - TRICINE N-tris(hydroxymethyl)methylglycine - TRIS tris(hydroxymethyl)aminomethane     

Genetic studies in Saudi Arabia: red cell enzyme, haemoglobin and serum protein polymorphisms.

Population genetic studies in Saudi Arabia are performed for EsD, GPT, AcP, ADA, AK, 6-PGD, PGM, C3, Tf, Hp, Gc, Pi, Bf, Hb, ABO-blood groups and Rh-factor, level of the third component of complement and immunoglobulins. The data are compared with reported frequencies in European and African populations.     

Chemistry of heparitin sulfate and heparin from normal tissues and from patients with Hunter syndrome.

Some structural features of heparitin sulfate excreted by patients with Hunter syndrome are described. It is shown, with the aid of heparitinases and heparinase from Flavobacterium heparinum, that the Hunter heparitin sulfate is a very complex structure composed of nine different disaccharide units containing regions akin to normal heparitin sulfate and regions akin the heparin. Two-thirds of the iduronic acid residues of Hunter heparitin sulfate are devoid of sulfate, contrasting with heparin in which most of the iduronic acid residues are sulfated. The isolation and characterization of the non-reducing ends of heparin and of the heparitin sulfates is also described. Based on these results the specificity of the heparinase and heparitinases as well as the biosynthesis of iduronic acid-containing heparin-like compounds is discussed.     

Cell recognition and adhesiveness: a possible biological role for the sulfated mucopolysaccharides.

The sulfated mucopolysaccharide composition of different neonate, adult and tumoral tissues is reported. It is shown that each tissue has a characteristic composition with respect to the relative amount, type and molecular size of chondroitin sulfate $\text{A}\text{C}$, chondroitin sulfate B and heparitin sulfate. Neonate and tumor tissues contain large amounts of chondrotin sulfate $\text{A}\text{C}$ which is nearly absent in most adult and normal tissues respectively. Based on these and other results a possible role for the sulfated mucopolysaccharides in cell recognition and adhesiveness is proposed.     

The Primulales: Serological contributions to the problem of their systematic position

The distribution of serological determinants in seed proteins from different species of Primulaceae, as well as from Ardisia crenulata (Myrsinaceae), Erica tetralix (Ericaceae), Manilkara zapota (Sapotaceae, Ebenales). Actinidia chinensis (Actinidiaceae) and Armeria maritima (Plumbaginaceae) has been determined by the use of corresponding rabbit immune sera. Serological reactions were carried out using a gel diffusion micro-method in calcium alginate gel, and a special pre-absorption technique was used in order to more closely specify the distribution of serological characteristics in the taxa under examination. While no systematic similarities were found between Primulales and Plumbaginales, a serological correspondence between Primulales and Ericales is very clear. It also occurs between these two taxa and species of the Theales. The Sapotaceae (as representatives of the Ebenales) showed some serological similarities with the Theales.     

Das mobile peritriche ciliat urceolaria convexa n. sp

The marine, mobile, peritrichous ciliate Urceolaria convexa n. sp., a harmless ectozoon on Anaitides mucosa (Oerstedt, 1843), is described from the coast of the Northsea near Büsum (FRG). It is characterized by its bellied lateral walls and the dome shaped peristome (name), which is clearly separated from the body. The adoral cilia describes slightly more than a full circle (400°) and extends nearly horizontally. The height of Urc. convexa n. sp. varies between 27 and 35 µm, the diameter between 32 and 56 µm, The macronucleus has roughly the form of the letter H.

Zoologisches Institut and Zoologisches Museum der Universität Hamburg, (Geschäftsführender Direktor: Prof. Dr. W. Villwock)     

Increased vascular smooth muscle contractility in TRPC6-/- mice

Among the TRPC subfamily of TRP (classical transient receptor potential) channels, TRPC3, -6, and -7 are gated by signal transduction pathways that activate C-type phospholipases as well as by direct exposure to diacylglycerols. Since TRPC6 is highly expressed in pulmonary and vascular smooth muscle cells, it represents a likely molecular candidate for receptor-operated cation entry. To define the physiological role of TRPC6, we have developed a TRPC6-deficient mouse model. These mice showed an elevated blood pressure and enhanced agonist-induced contractility of isolated aortic rings as well as cerebral arteries. Smooth muscle cells of TRPC6-deficient mice have higher basal cation entry, increased TRPC-carried cation currents, and more depolarized membrane potentials. This higher basal cation entry, however, was completely abolished by the expression of a TRPC3-specific small interference RNA in primary TRPC6(-)(/)(-) smooth muscle cells. Along these lines, the expression of TRPC3 in wild-type cells resulted in increased basal activity, while TRPC6 expression in TRPC6(-/-) smooth muscle cells reduced basal cation influx. These findings imply that constitutively active TRPC3-type channels, which are up-regulated in TRPC6-deficient smooth muscle cells, are not able to functionally replace TRPC6. Thus, TRPC6 has distinct nonredundant roles in the control of vascular smooth muscle tone.     

Apparent charge of binding site in ion-translocating enzymes: kinetic impact

Recently, we presented a general scope for the nonlinear electrical properties of enzymes E which catalyze translocation of a substrate S with charge number z_S through lipid membranes (Boyd et al. J. Membr. Biol. 195:1–12, 2003). In this study, the voltage sensitivity of the enzymatic reaction cycle has been assigned to one predominant reversible reaction step, i.e. the reorientation of either E or ES in the electric field, leaving the reorientation of the alternate state (ES or E) electroneutral, respectively. With this simplification, the steady-state current–voltage relationships (IV) assumed saturation kinetics like in Michaelis–Menten systems. Here, we introduce an apparent charge number z_E of the unoccupied binding site of the enzyme, which accounts for the impact of all charged residues in the vicinity of the physical binding site. With this more realistic concept, the occupied binding site assumes an apparent charge of , and IV does not saturate any more in general, but exponentially approaches infinite or zero current for large voltage displacements from equilibrium. These nonlinear characteristics are presented here explicitly. They are qualtitatively explained in a mechanistic way, and are illustrated by simple examples. We also demonstrate that the correct determination of the model parameters from experimental data is still possible after incorporating z_E and its corollaries into the previous model of enzyme-mediated ion translocation.     

Dynamics of bone marrow changes in patients with chronic idiopathic myelofibrosis following allogeneic stem cell transplantation

Scant knowledge exists about the dynamics of fibro-osteosclerotic bone marrow (BM) lesions and regeneration of hematopoiesis following allogeneic peripheral stem cell transplantation (SCT) in chronic idiopathic myelofibrosis. Therefore, an immunohistochemical and morphometric study was performed on BM biopsies in 20 patients before and at standardized intervals (days 30 through 384) following SCT. In responding patients, a total regression of the pretransplant increased fibrosis was completed in the posttransplant period after about six months, while the extent of osteosclerosis did not change significantly during observation time. The quantity of CD61+ megakaryocytes including precursors was strikingly variable after SCT and, by using planimetric methods, atypical microforms exhibiting a dysplastic aspect could be demonstrated. These anomalies may be responsible for posttransplant thrombocytopenia. CD34+ progenitor cells were increased before transplantation, however, their number declined rapidly to normal values in responding patients. Nucleated erythroid precursors revealed a decreased amount before and after SCT accounting for anemia. Large clusters of this cell lineage indicated an initial hematopoietic reconstitution comparable with the expansion of the neutrophil granulopoiesis. Proliferative activity and apoptosis showed an increase until one year after SCT that implied a still regenerating hematopoiesis in keeping with an enhanced cell turnover.