Glomerular lesions in Aleutian disease of mink (Mustela vison): a morphological and differential morphometrical study.

A morphological and morphometrical study has been carried out on glomerular lesions in mink with spontaneous Aleutian disease, using the WHO classification for Systemic Lupus Erytematous Nefritis. 154 renal samples from sick animals and 10 samples from uninfected mink were processed by routine histopathological techniques and metacrylate inclusions. The samples were studied quantitatively with an automatic image analyzer. 5 forms of glomerulonephritis (GN) were identified: mesangial glomerulonephritis (n = 13), focal and segmental GN (n = 10), diffuse GN (n = 99), membranous GN (n = 12) and advanced sclerosing GN (n = 10) and were associated with the degree of interstitial plasmocytosis. Glomerule morphometry was shown to be an excellent method for identifying the type of lesion, while it quantified the participation of various glomerular elements in the lesion.     

Interaction of fructose with the glucose permease of the cyanobacterium Synechocystis sp. strain PCC 6803.

Fructose was bactericidal for the cyanobacterium Synechocystis sp. strain PCC 6803. Each of ten independently isolated fructose-resistant mutants had an alteration of the glucose transport system, measured as uptake of glucose or of 3-O-methyl-D-glucose. In the presence of the analog, the wild-type Synechocystis strain was protected against fructose. Two mutants altered in photoautotrophy were also isolated.     

Stimulation of intestinal adenylate cyclase by cholera toxin in malnourished rats

The stimulation of intestinal adenylate cyclase by cholera toxin (CT) was studied in normal and malnourished rats 4 to 24 hr after a 30-min incubation of intestinal loops with the toxin. Whereas in control rats the enzyme activity returned to basal levels after 12 hr of incubation, in malnourished rats the activity of the enzyme remained significantly elevated even after 24 hr of the initial incubation. Malnourished animals had a reduced turnover rate of intestinal cells as determined by thymidine kinase activity. The delayed turnover of intoxicated cells may account for continuous activation of mucosal adenylate cyclase and possibly for prolongation of diarrhea in malnutrition.     

Occurrence of oscillations in ATP synthesis and hydrolysis in chromatophores of Rhodospirillum rubrum

The conditions under which an oscillatory behaviour is observed during net hydrolysis or synthesis of ATP in chromatophores of Rhodospirillum rubrum FR1 are described. In the case of ATPase the oscillations are observed at low temperature (ca. 11°C) in the dark after an initial transient behaviour. These oscillations are attenuated or disappear by the addition of an uncoupler.Oscillations are also observed during ATP synthesis. At 3°C the oscillations appear spontaneously if photophosphorylation is measured during a sufficiently long time. At 30°C the mere intercalation of a dark period also at 30°C is sufficient to trigger the oscillations in the following light period.Abbreviations Bchl Bacteriochlorophyll - FCCP carbonyl cyanide p-trifluoromethoxyphenyl hydrazone - PMS phenazine methosulfate - TMPD, N,N,N,N tetramethyl-1,4-phenylenediamine Dedicated to Prof. Dr. Gerhart Drews as a homage for his permanent example as hard worker and careful scientist and also for his remarkable human quality     

Immunoelectrophoretic approach to the metabolic regulation of glutamine synthetase in Rhodopseudomonas capsulata E1F1: role of glutamine

Anti-glutamine synthetase serum was raised in rabbits by injecting purified glutamine synthetase (GS) of the phototrophic bacterium Rhodopseudomonas capsulata E1F1. The antibodies were purified to monospecificity by immunoaffinity chromatography in GS-sepharose gel. These anti-GS antibodies were used to measure the antigen levels in crude extracts from bacteria, grown phototrophically with dinitrogen, nitrate, nitrite, ammonia, glutamate, glutamine or alanine as nitrogen sources. The amount of GS detected by rocket immunoelectrophoresis was proportional to Mn²⁺-dependent transferase activity measured in the crude extracts. Addition of GS inhibitor l-methionine-d,l-sulfoximine (MSX) to the actively growing cells promoted increased antigen levels, that were not found in the presence of glutamine or chloramphenicol. The ammonia-induced decrease in GS relative levels was reverted by MSX. GS levels remained constant when phototrophically growing cells were kept in the dark.Abbreviations GS glutamine synthetase - MOPS 2-(N-morpholine) propane sulfonate - MSX l-methionine-d,l-sulfoximine     

Wheat germ agglutinin-resistant variant of EL4 containing altered oligosaccharides as a target cell for cytotoxic T cells

A lectin-resistant variant of the murine EL4 lymphocytic leukemia cell line was selected in the presence of wheat germ agglutinin for low levels of cell-surface sialic acid. H-2Kb was the major internally radiolabeled H-2b molecule on the cell-surface of WD1, and it was not sialylated, as determined by two-dimensional gel analysis. Endo-beta-N-acetylglucosaminidase H treatment of the WD1 membrane fractions suggested that the oligosaccharides on the cell-surface H-2Kb molecule were complex, but nonsialylated. Monoclonal antibody inhibition of the allogeneically primed cell-mediated cytotoxicity (CMC) reaction indicated that the T cells (BALB/c anti-EL4; H-2d anti-H-2b) were specific only for the H-2Kb target cell antigen. These WD1 variant cells were used as targets in the CMC assay using anti-H-2Kb T cells and compared with the parent EL4 in vitro line. The change in the cell-surface oligosaccharide did not affect the susceptibility to lysis by the cytotoxic T lymphocytes even though there were 2.5-fold more H-2Kb antigens on the WD1 variant cell (1.5 X 10(5) sites/cell) than on the parent EL4 in vitro cell (5.9 X 10(4) sites/cell). It was possible to isolate highly purified preparations of H-2Kb from either the EL4 or the WD1 line using a monoclonal antibody affinity column. Interestingly, the variant WD1 cell would no longer grow in the peritoneal cavity of the syngeneic C57BL/6 mouse.     

Chlorophyll-protein and polypeptide composition of Mn-deficient sugar beet thylakoids

The chlorophyll-protein and polypeptide composition of manganese deficient and control sugar beet thylakoids was examined using three different detergent-electrophoresis systems. On a per chlorophyll basis, manganese deficiency reduced the amounts of CPa complex (separated by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis), and CP 47 and CP 43 complexes (separated by octylglucoside/SDS-polyacrylamide gel electrophoresis) without decreasing the amounts of light harvesting complexes. Lithium dodecylsulfate/Triton X-100 polyacrylamide gel electrophoresis showed that manganese deficiency decreased several thylakoid polypeptides, including a chlorophyll b containing 30 kilodalton chlorophyll-protein complex, but did not decrease the amounts of 28 and 29 kilodalton light-harvesting chlorophyll b-containing polypeptides.     

Production,by filamentous,nitrogen-fixing cyanobacteria,of a bacteriocin and of other antibiotics that kill related strains

Colonies of sixty-five filamentous cyanobacteria were screened for the production of temperate phages and/or antibiotics on solid medium. None of them was observed to release phages. However, seven N₂-fixing strains were found to produce antibiotics very active against other cyanobacteria. The antibiotic produced by Nostoc sp. 78-11 A-E represents a bacteriocin of low molecular weight. Nostoc sp. ATCC 29132 appears to secrete, together with an antibiotic, a protein that inhibits its action.     

Regulatory interaction of photosynthetic nitrate utilization and carbon dioxide fixation in the cyanobacterium Anacystis nidulans

The rate of photosynthetic nitrate utilization in Anacystis nidulans is strongly influenced by the availability of carbon dioxide. This dependence can be relieved by inhibiting the metabolism of the ammonium derived from nitrate reduction. Nitrate uptake seems to be modulated through a sensitive regulatory system integrating the photosynthetic metabolism of carbon and nitrogen, with CO₂ fixation products antagonizing the inhibitory effect of ammonium derivatives.