Sulphamerazine toxicity in cut-throat trout broodfish Salmo clarki (Richardson)

Treatment of cut-throat trout broodfish Salmo clarki (Richardson) with Sulphamerazine at 220 mg/kg (10 g/100 1b) of fish/day for 14 days resulted in severe kidney histopathology and increased mortality among males. Experimental data presented showed that cut-throat trout broodfish were extremely sensitive to Sulphamerazine toxicity. Hydropic degeneration of renal tubule epithelium and haemorrhage into tubule lumens were observed in kidneys of both male and female trout, but was more severe in the former. Death, which occurred only in males, was correlated with spawning stress and impaired renal function.     

Lactation-associated redistribution of the glial fibrillary acidic protein within the supraoptic nucleus

Summary Three clones of myeloproliferative virus (MPV)-transformed rat fibroblasts (NRK) with different growth properties and morphology were transplanted to athymic nude mice. Presence of carbohydrate-binding proteins was inferred by fluorescence microscopy using fluorescent, glycosylated markers. Salt and detergent extracts of tumors from this model system were fractionated under identical conditions on different sets of Sepharose columns, to which lactose, asialofetuin, melibiose, mannan and fucose had been covalently linked. Successive elution by chelating reagent and specific sugar resulted in isolation of the different Ca²⁺-dependent and Ca²⁺-independent endogenous carbohydrate-binding proteins that were assayable as agglutinins. In comparison, the different tumors displayed a pattern with qualitative and quantitative alterations. Since protein-carbohydrate interaction mediated by carbohydrate-binding proteins (lectins) is of importance for cognitive processes, it is remarkable that the pattern of membrane glycoproteins, isolated by affinity chromatography on resins with immobilized plant lectins, had also been found to reveal certain individual properties for receptors specific for peanut agglutinin (PNA) and Ulex europaeus agglutinin (UEA). These demonstrated differences within the system of protein-carbohydrate interaction suggest that endogenous lectins and their ligands have potential significance as markers defining a certain phenotype within this tumor model system.Dedicated to Prof. Dr. W. Lamprecht on the occasion of his 60th birthday     

A mevalonate requirement for maintenance of fatty acid and protein synthesis during hormonally stimulated development of mammary gland in vitro

The effect of compactin on hormonally induced lipogenesis and protein synthesis was studied in vitro in explants of mammary gland from mid-pregnant rabbits. Compactin blocks mevalonate synthesis by the specific inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase, and in this system, culture with 10 microM compactin for 24, 48, and 72 h inhibited incorporation of [1-14C]acetate (but not [2-14C]mevalonate) into sterol by 98, 95, and 86%, respectively. Removal of compactin prior to assay rapidly reversed this effect and was associated with increased tissue 3-hydroxy-3-methylglutaryl-CoA reductase activity. Fatty acid synthesis (measured by incorporation of [1-14C]acetate or [4,5-3H]leucine) and protein synthesis (measured by incorporation of [4,5-3H]leucine) were both inhibited by around 50% after culture with compactin. This inhibition was not rapidly reversed by removal of compactin prior to assay, but it was prevented by inclusion of 1 mM mevalonolactone in the culture medium. After removal of compactin and continued culture in its absence for 24 h with hormones, the normal tissue capacity for fatty acid and protein synthesis was restored, indicating no permanent cell damage. The results suggest a specific requirement for mevalonate (or derived products) for the hormonal maintenance of the increased fatty acid and protein synthesis characteristic of the development of the mammary gland.     

A simple phenomenological thermodynamic model for protein partitioning in reversed micellar systems

A simple thermodynamic model is developed for the partitioning of proteins between a bulk aqueous solution and a reversed micellar organic phase by assuming that a pseudo-chemical equilibrium is established when proteins in solution interact with a non-integral number of empty micelles to form the protein-micelle complex. From the equilibrium constant for this reaction, which is related to both the chemical and electrical free energy changes associated with the transfer of the proteins between the two phases, a simple expression is derived for the partition coefficient as a function of pH and surfactant concentration. Assumptions include a linear variation in protein net charge with pH, and a linear decrease in protein-micelle complex size with increasing protein charge. Results on the solubilization of ribonuclease-a and concanavalin-a in Aerosol-OT/isooctane organic solvents were well-correlated by the model equation, and the estimated parameters were of the expected order of magnitude as estimated based on the known physical properties of the system components.List of Symbols F C/mol Faraday's constant - G J/mol standard free energy change on solubilization - G J/mol standard free energy change in the absence of charge effects - K partition coefficient - K _eq (mol/m³)^–n equilibrium constant for pseudo-reaction (1) - M micelle - N _ag empty micelle aggregation number - n number of empty micelles required to form protein/micelle complex - n ₀ number of empty micelles required at zero net protein charge - P protein - PM protein/micelle complex - pI protein isoelectric point - R J/mol K gas law constant - S surfactant - z protein charge - slope of protein titration curve - change in micelle size, n, per unit change in charge - V electrostatic potential difference     

Galactose-specific elimination of human asialotransferrin by the bone marrow in the rabbit

Rabbit bone marrow accretes and degrades human asialotransferrin in vivo through a mechanism that recognizes the exposed galactose groups in this glycoprotein. After the liver, rabbit bone marrow is the second mammalian tissue now being identified as possessing a galactose-specific pathway for the elimination of a plasma protein. However, comparative studies with desialylated glycoproteins containing bi-, tri-, and tetraantennary glycans (asialofetuin, asialoorosomucoid, chicken α₁-acid glycoprotein, and rabbit transferrin) indicate that the bone marrow recognizes fewer glycan structures than does the liver. Optimal uptake and degradation of an asialoglycoprotein by the bone marrow requires the presence of biantennary glycans.