Bryologische Fragmente

Ohne Zusammenfassung     

Attempt to detect recombination between B-F and B-L genes within the chicken B complex by serological typing,in vitro MLR,and RFLP analyses

In search for recombinants within the chicken major histocompatibility B complex, 1155 animals from crosses between the congenic lines CB (B¹²) and CC (B⁴) were tested with alloantibodies and monoclonal antibodies for the B-F (class I), B-L (class II), and B-G (class IV) antigens and by mixed lymphocyte reaction. The absence of detectable recombination was confirmed by restriction fragment length polymorphism analysis with B-L and B-F probes. Together with previous reports, this indicates that the distance between the B-F and B-L loci is below 0.01 centimorgan.     

Physiological control and process kinetics of clavine alkaloid production byClaviceps purpurea

Summary Kinetic parameters of production of clavine alkaloids were evaluated in twoClaviceps purpurea strains. Mutagenesis brought about enhanced resistance of the biosynthetic system towards alkaloids. Addition of glucose into the fermentation medium altered the zero order kinetics of production to activation-inhibition kinetics. The glucose treatment allowed performance of both elymoclavine-inhibitionless and clavine alkaloid-decompositionless fermentations if a combination of fermentation and separation units in a closed loop was used.Nomenlacture k ₁ rate constant of agroclavine synthesis (mg Agro · mg Elymo/l·g DW·day for stage 1, mg Agro/g DW·day for stage 2) - k ₂ parameter describing inhibition of agroclavine formation rate by elymoclavine (mg Elymo/l) - k ₃ specific rate of agroclavine decay (l/g DW·day) - k ₄ maximal specific rate of elymoclavine synthesis (stage 1, 1/g DW·day, stage 2, mg Elymo/g DW·day) - k ₄ ^– maximal specific rate of elymoclavine synthesis in stage 1 (inhibition-activation mechanism) (mg Elymo/g DW·day) - k ₅ physiological constant describing the elymoclavine decay rate (l²/g DW·day·mg Elymo) - k ₅ ^– physiological constant describing the activation of elymoclavine biosynthesis by elymoclavine (mg Elymo/l) - k ₆ physiological constant describing the repression of elymoclavine biosynthesis by elymoclavine (mg Elymo/l) - k ₇ maximal specific growth rate (1/day) - k ₈ specific rate of biomass decay (l/g DW·day) - A agroclavine concentration (mg/l) - E elymoclavine concentration (mg/l) - r _A specific rate of agroclavine biosynthesis (mg Agro/g DW·day) - r _E specific rate of elymoclavine biosynthesis (mg Elymo/g DW·day) - r _i specific rate of alkaloid biosynthesis (mg alkaloid/g DW·day) - X dry biomass concentration (g/l) - specific growth rate (1/day) Abbreviations Agro agroclavine - Elymo elymoclavine - Chano chanoclavine - DW dry weight of biomass     

Voluntary progression order in captive rhesus macaques

The sequence in which 14 laboratory rhesus macaques left their home enclosure during a routine catching procedure was recorded on 30 occasions during 6 weeks. The animals were trained to voluntarily exit one by one and enter a transport cage for weighing and/or treatment. Mean weekly exit orders cross-correlated significantly, and individuals retained their exit positions with remarkable consistency throughout the study period. An animal's position did not depend on its sex, age, or dominance rank. The oldest female never failed to enter the transport cage as number 1. When she was prevented from taking the lead, the group was hesitant but eventually proceeded in the usual order. Food was a strong, yet not absolute, incentive for the monkeys to cooperate. If they could not expect a reward, they took more time before proceeding, but did so in the habitual order. The predictability of the exit sequence has practical managerial value because it makes it possible for a single person to quickly catch a selected group member when necessary.     

Stabilities of hydroxyl radical spin adducts of PBN-type spin traps.

The stability of the hydroxyl spin adduct of nine different PBN-type spin traps has been examined in phosphate buffer solutions of various pH. The hydroxyl adduct is produced by short illumination of hydrogen peroxide with UV light in the presence of spin trap and the decay of its EPR signal followed. The stability measured by the half life of the first-order decay is strongly dependent on the pH of the solution and the structure of the aromatic ring used in the trap. All hydroxyl adducts are more stable in acidic media. tert-Butyl hydroaminoxyl is detected as a degradation product of the hydroxyl adduct from all spin traps.     

Immunohistochemical localization of porcine diazepam-binding inhibitor (DBI) to rat endocrine pancreas

Summary The occurrence of diazepam-binding inhibitor (DBI), isolated and characterized from porcine upper intestine, was examined in the pancreas of Sprague-Dawley albino rats using indirect immunofluorescence. The polypeptide was found in the endocrine Langerhans islets and, utilizing double-labelling controls, it was shown to be present within the peripherally located glucagon-containing cells. Regulation of islet hormone production may therefore be under DBI control.     

Oxidation of cyanide to the cyanyl radical by peroxidase/H2O2 systems as determined by spin trapping

The cyanyl radical was formed during the oxidation of potassium or sodium cyanide by horseradish peroxidase, lactoperoxidase, chloroperoxidase, NADH peroxidase, or methemoglobin in the presence of hydrogen peroxide. The spin adducts of the cyanyl radical with 5,5-dimethyl-1-pyrroline-N-oxide and N-tert-butyl-alpha-phenylnitrone were quite stable at neutral pH. The identity of these spin adducts could be demonstrated using 13C-labeled cyanide and by comparison with the spin adducts of the formamide radical, a hydrolysis product of the cyanyl radical adduct. The enzymatic conversion of cyanide to cyanyl radical by peroxidases should be considered in addition to its well-known role as a metal ligand. Furthermore, since cyanide is used routinely as an inhibitor of peroxidases, some consideration should be given to the biochemical consequences of this formation of the cyanyl radical by the catalytic activity of these enzymes.     

Courtship behavior among musk-ox males kept in confinement

During twelve 2-h observation sessions courtship behavior was recorded among seven musk-ox males (Ovibos moschatus) kept in a paddock together with six females. The animals were sexually mature and of the same age. Foreleg kicking and genital sniffing were more common than mounting. All three activities were of a nonaggressive nature but were shown almost exclusively by dominants toward subordinate partners. Assuming the role of courted females, recipients were never the target of aggressive acts. It was concluded that courtship among mature musk-ox males functions as a nonaggressive reinforcement of dominance, promoting low-risk coexistence of males.     

Oxygen- and carbon-centered free radical formation during carbon tetrachloride metabolism. Observation of lipid radicals in vivo and in vitro

Free radical reactions involved in the metabolism of carbon tetrachloride by rat liver have been considered to be a cause of at least part of the injury resulting from exposure to this halocarbon. In an earlier study employing electron spin resonance and spin-trapping techniques, we demonstrated that trichloromethyl (13.CCl3) radicals are readily observed in rat liver microsomes metabolizing 13CCl4, and that the same radical could be shown to form in vivo in the liver of intact rats given a single dose of 13CCl4. This report describes the production of lipid dienyl (L.) and oxygen-centered lipid radicals (LO. or LOO., or both) in in vitro systems metabolizing 13CCl4, and also the formation of lipid dienyl radicals (L.) in liver of intact animals exposed to CCl4. The radicals appear to be produced in a sequence of reactions governed among other things by the oxygen tension in the system. The lipid radicals (L.) which form in intact liver of CCl4-treated rats are apparently the result of an attack on lipids of the endoplasmic reticulum by 13.CCl3 radicals formed by reductive cleavage to CCl4 and are the initial intermediates in the process of lipid peroxidation. These investigations demonstrate that while the events occurring in liver microsomes in vitro appear to parallel those which take place in intact liver in vivo, the conditions in vivo make the spin-trapping studies of radicals in intact animals much more selective than it is in vitro for a given spin trap, and requires the use of more than one type of spin-trapping agent to detect different radical species in vivo.