Rate Equations and Product Yields of Serine Proteinase Catalysed Transfer Reactions

The steady state rate equations of transfer reactions catalysed by enzymes that follow the serine proteinase reaction mechanism in their hydrolysis reactions, have been solved and integrated. The integrated equations allow for calculations of maximal yields of product and of the time, t_max, at which that yield is present in a given reaction mixture. These important quantities have not been dealt with in previous theoretical studies of such systems.     

A Simple and Safe Device for Spreading Ultrathin Sections with Chloroform

A simple and safe device for spreading ultrathin sections for electron microscopy is described. The use of this device minimizes the release of chloroform vapor during section spreading.     

Succession and soil development in man-made coastal ecosystems at the Baltic Sea

By the creation of Køge Bay Seaside Park in 1978 the opportunity was given to study the establishment of vegetation and primary succession in a man-made coastal area. As the soil consists of marine material from the Baltic Sea, no organic matter or seedbank was present. The first steps of primary succession were followed in 1980, when the initial inventories of flora immigration and soil development were carried out in coastal grasslands and plantings. The surveys were repeated in 1992 and 1993. Except for the planted woody species and a few sown grasses, all other species of plants have reached the area through natural dispersal of diaspores. The total number of species in the permanent plots has increased from 26 in 1980 to 91 in 1993. The results indicate that this number will continue to increase in the coming years until a certain level. Then it will probably decrease as a result of competition from woody species, unless the vegetation is kept in a steady state by disturbances or management. Today the area is very far from the initial situation, and the off-shore barrier has changed towards a landscape dominated by small groves and grasslands of an urban common type.     

Transplantation of a time-signal in honeybees

Summary It has been possible — by transplantation of brain tissue (i.e. mushroom-bodies) — to perform an interindividual transfer of a learned time-signal in honeybees. The information of the donor bees becomes determinative for the temporal activity pattern of the recipients about 3 to 4 days following transplantation.As seen from histological investigations done in parallel, the donor tissue is treated as a xenograft by the recipient's organism including disintegration and encapsulation processes. These observations give evidence for a humoral transfer of information.The results are discussed from the point of view of the analysis of the mechanism of time reception.Dedicated to Prof. Dr. H. Autrum on the occasion of his 70th birthdaySupported by the Akademie der Wissenschaften und der Literatur zu Mainz, the Stiftung Volkswagenwerk and the Deutsche ForschungsgemeinschaftAll observations done were individual per hand registrations. We want to give thanks to all people in the department who helped us to do the experiments.     

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.     

Regeneration of masseter muscle following lidocaine-induced degeneration. A histochemical study.

The histoenzymatic characteristics of regenerating myofibers of rat masseter muscle following injection of 1% lidocaine, as well as morphometric and histochemical characteristics of the typical myofibers, were investigated. Myoblasts appeared initially by day 1 among numerous macrophages within the confines of degenerating myofibers. Myotubes predominated by the 3rd day. Complete regeneration of the muscle occurred by at least 45 days. Phosphorylase activity was absent at day 1 and reappeared by the 5th day when the regenerating myofibers showed slight activity. By the 15th day the myofiber types had partly differentiated; red myofibers were smaller and stained less intensely than the white myofibers. Myotubes stained uniformly for succinic dehydrogenase activity from 3 until 5 days. After 5 days this staining increased gradually. Myofiber types began differentiation by 15 days and were fully differentiated by 45 days. ATPase activity was barely evident by 1-3 days. This activity appeared uniformly low up to 5 days and increased to an intensity comparable with that of the typical myofiber by 15 days. Slight leucine aminopeptidase activity occurred in macrophages 1 day following injection. By 3 days this activity appeared in the remaining myoblasts and in the myotubes. Some activity was found in the fibroblasts. This staining intensity at 5 days was equal to that of earlier lesions. A trace of this activity was found at 7 days, and none at 15 days. Glucose-6-phosphate dehydrogenase activity was present in the macrophages by day 1. It increased by 3 days and occurred mainly in myoblasts and myotubes. This activity decreased by 5 days, and none was found by 7 days.