Ribonucleic acid labelling perfused livers of protein-fed and protein-deprived rats

Several observations suggest an increased RNA synthesis in livers of protein-deprived rats, though the RNA/DNA ratio is decreased. A number of hormones may be involved in these changes. Therefore, we studied in RNA metabolism in isolated perfused livers taken from protein-fed and protein-deprived rats. (3H)-orotic acid was given to the rats 2 h before liver explantation, and (14C)-orotic acid was added to the perfusate. Other rats, called controls in vivo, whose livers were not transplanted were also given (3H)-orotic acid followed by (14C)-orotic acid. The livers of these rats, which were not hormone supplemented, were labelled for the same length of times as the livers in vitro. The ratio specific RNA radioactivity/specific nucleotide radioactivity x RNA/DNA was determined and taken as a measure of the RNA synthesis per liver cell. In the controls in vivo, this ratio was significantly higher for protein-deprived than for protein-fed rats. In livers from the protein-fed rats, labelling in vitro increased significantly when growth hormone, hydrocortisone, insulin and tri-iodothyronine were added to the perfusate. Labelling was also significantly higher in these livers than in the controls in vivo. In livers from protein-deprived rats, the ratio in question was the same whether the hormones were added to the perfusate or not, and was significantly lower than in the controls in vivo. Differences in RNA labelling are thus obtained in our in vitro system. Gel electrophoresis of RNA demonstrated normal RNA labelling, showing that the system is suitable for studying liver RNA synthesis. Further refinement can be made by studying the labelling of UTP and CTP. The results might suggest that the liver from a protein-fed rat, explanted in vitro, may increase its RNA synthesis under the influence of the four hormones in question, and that the RNA synthesis of the liver of a protein-deprived rat is high in-vivo and that it might decrease, when it is explanted to in vitro conditions.     

Dietary, bacterial, and host genetic interactions in the pathogenesis of transmissible murine colonic hyperplasia

Transmissible murine colonic hyperplasia, cuased by a variant of Citrobacter freundii (4280). was shown to be modified by diet and by host strain and species. Four different diets fed to mice inoculated with C frundii 4280 were found to have a significant but varying influence on the severity of hyperplasia. Diet also influenced the colonic crypt height of uninoculated, control mice. F344 rats, Syrian hamsters, and NIH Swiss [N:(S)], C57BL/6J, C3H/HeJ, and DBA/2J mice were inoculated with C freundii 4280. Marked strain differences were noted in the mice in mortality and severity of the colonic hyperplasia. The NIH Swiss mice had the greatest and the C57BL/6J mice had the least mucosal hyperplasia. The rats and hamsters did not develop disease or maintain infection after inoculation with the organism. Twenty isolates of Citrobacter from a range of biologic sources were inoculated into susceptible mice, but only mice inoculated with C freundii 4280 developed the disease.     

Improvement of anther culture technique: Activated charcoal bound in agar medium in combination with liquid medium and elevated CO2 concentration

Anthers of different species of the genera Anemone, Clematis, Papaver and Nicotiana were cultured by floating on a liquid medium which overlay an agarified charcoal medium . This technique proved to be superior to conventional methods i.e. culture on either solid or liquid media. Cold treatment of Anemone anthers for 7 days after inoculation on the double layer medium gave about the same frequency of embryos per anther as corresponding cultures cold treated before inoculation. An elevation of the CO₂ concentration to 2% stimulated embryogenesis in anther cultures of Anemone canadensis, Anemone vitifolia, Papaver setigerum and Papaver radicatum . Cold treatment of cultures of Anemone canadensis inhibited embryogenesis if the ensuing culture was performed in 2% CO_2. On the other hand, cold treatment was stimulating, with an optimum of about 20 days, if the cultures were maintained in normal air. Chemical analysis of untreated anthers of Anemone canadensis showed the presence of abscisic acid (2.2 × 10⁻⁶ g/g anthers). Cold treatment reduced the concentration of abscisic acid to 0.6 × 10⁻⁶ g/g anthers. By use of assays with Lemna gibba as test organism, activated charcoal was shown to adsorb abscisic acid that was added to the medium. Medium treated with charcoal before inoculation of anthers of Anemone canadensis provided to inhibit embryo production.     

Nitrogenase from Rhodospirillum rubrum Relation between ‘switch-off’ effect and the membrane component. Hydrogen production and acetylene reduction with different nitrogenase component ratios

Nitrogenase activity of ‘membrane-free’ extracts, produced from nitrogenstarved Rhodospirillum rubrum to which 4 mM NH⁺₄ had been added is only about 10% of the activity in the control. The activity could be restored to 80% by including the membrane component, earlier found to activate R. rubrum nitrogenase, in the reaction mixture. The relation between this ‘switch-off/switch-on’ effect and the function of the membrane component is discussed.Hydrogen production catalyzed by R. rubrum nitrogenase is also dependent on activation by the membrane component. Hydrogen production is inhibited by acetylene but the degree of inhibition is dependent on the nitrogenase component ratio. The strongest inhibition is achieved at low MoFe protein/Fe protein ratios. The $\text{ATP}\text{2 e}{}^{\mathrm{?}}$ values are 4–5 at the component ratios giving the highest activity and increase at high MoFe protein/Fe protein ratios. CO inhibits acetylene reduction but has no effect on the hydrogen production.     

The families of bitunicate ascomycetes

The morphology and nomenclature of ca. 195 families of bitunicate or alleged bitunicate ascomycetes are discussed. Available representatives of these families were studied especially with respect to the morphology of the asci and ascospores. The morphology of the ascomata, etc. was studied in the SEM in 73 species. The following morphological terms are introduced: hamathecium, pseudoprototunicate, pseudofis–situnicate, semifissitunicate, and umbilicus. The following taxa are described as new: Coccodiniaceae O. Erikss. fam. nov., Microtheliopsidaceae O. Erikss. fam. nov., Amarenomyces O. Erikss. gen. nov., and Euantennaria abietina O. Erikss. sp. nov. The name Lecanidiaceae is proposed to replace Patellariaceae Corda, and Cyanoder–mella to replace Cyanoderma Höhn. The Massariaceae are treated as Trypetheliaceae subfam. Massarioideae (Nits.) O. Erikss. The following new combinations are proposed: Amarenomyces ammophilae (Lasch) O. Erikss., Cyanodermella viridula (Berk. & Curt.) O. Erikss., C. Candida (Setch.) O. Erikss., Dictyotrichiella delicatula (Ves–tergr.) O. Erikss., Laurera sepulta (Mont.) O. Erikss., Splanchnonema superans (Mull. Arg.) O. Erikss. and Thelenella antarctica (M. Lamb) O. Erikss. The origin and evolution of the Ascomycetes are discussed, and the importance of paedomor–phosis in the transspeciation of the group is emphasized. The stratigraphic classification of the Ascomycetes is discussed. In a transitional classification of the Ascomycetes, 109 monophyletic entities (clades) are recognized. La morphologie et la nomenclature ?environ 195 families ?ascomycétes bituniques ou soit–disant bituniques sont étudiées, spécialement en respectant la morphologie des asques et des ascospores. La morphologie des ascocarpes, etc. de 73 espèces fut étudiée dans le SEM. Les termes morphologiques suivants sont introduits: hamathecium, pseudoprototunique, pseudofissitunique, semifissitunique et umbilicus. Ces nouveaux taxa sont decrits: Coccodiniaceae O. Erikss. fam. nov., Microtheliopsidaceae O. Erikss. fam. nov., Amarenomyces O. Erikss. gen. nov. et Euantennaria abietina O. Erikss. sp. nov. Le nom Lecanidiaceae est proposéà la place de Patellariaceae Corda, Cyanodermella à la place de Cyanoderma Höhn. Les Massariaceae sont traitées comme Trypetheliaceae subfam. Massarioideae (Nits.) O. Erikss. Les nouvelles combinations suivantes sont proposées: Amarenomyces ammophilae (Lasch) O. Erikss., Cyanodermella viridula (Berk. & Curt.) O. Erikss., C. Candida (Setch.) O. Erikss., Dictyotrichiella delicatula (Vestergr.) O. Erikss., Laurera sepulta (Mont.) O. Erikss., Splanchnonema superans (Müll. Arg.) O. Erikss. et Thelenella antarctica (M. Lamb) O. Erikss. ?origine et ?évolution des ascomycètes sont discutées, et I'importance de la paedomorphose dans la transspeciation du groupe est mise en évidence. La classification stratigraphique des ascomycètes est discutée. Dans une classification de transition des ascomycètes, 109 entités monophyletiques sont reconnues.     

Lateral enzyme topology in the rough endoplasmic reticulum of rat liver

Summary Rough microsomes were subfractionated on the basis of different properties in order to investigate the nature and extent of the enzyme heterogeneity of these vesicles. A discontinuous gradient, containing monovalent cations allowed the separation of a ribosome-poor membrane fraction which was enriched in electron transport enzymes and relatively poor in phosphatases. Zonal centrifugation on a stabilizing gradient separated 3 fractions characterized by enrichment of electron transport enzymes, glucose-6-phosphatase and adenosinetriphosphatase, respectively. An essentially similar pattern was seen when ribosomes were removed with EDTA and the denuded vesicles subfractionated on a sucrose gradient. Rough microsomes from phenobarbitaltreated rats exhibited the same pattern both qualitatively and quantitatively. It appears that electron transport enzymes and two types of phosphatases are heterogeneously distributed among rough microsomal vesicles.This work has been supported by grants from the Swedish Medical Research Council. The authors wish to thank Mrs. Ulla-Britta Torndal for her valuable technical assistance     

Copper Toxicosis in Bedlington Terriers

Copper toxicosis of Bedlington Terriers (Chronic progressive hepatitis) is a genetically transmitted disease. The typical feature of this disease is accumulation of copper in the liver tissue. The changes vary from mild hepatitis to chronic progressive hepatitis and cirrhosis. The material of this study consists of 2 cases of copper toxicosis examined at the Department of Pathology in Helsinki in the years 1980–82. Moreover a re-examination of tissue samples was made of all Bedlington Terriers examined during the years 1969–1982 at the same department. Six of the 14 examined dogs showed a positive reaction for copper in their liver tissues. The possible relationship of the examined dogs is not yet known.