Quelques aspects biochimiques de la physiologie des radis (Raphanus sativus L.) traités par la simazine.*

L'action de la simazine ne peut être réduite au seul fait de l'inhibition de la photosynthése. Chez le radis (Raphanus tativus L.). la simazine a provoqué d'abord une baisse considérable du traux des glucides dans le limbe des plantes trailées. Cette diminution a affecté e principalement le glucose et le fructose ct plus encore le saccharose, cependant qu'apparaissait du glycérol. Dans la racine, les osides et les oses ont augmenté pendant les 3 jours qui suivirent le traitement et ont diminué ensuite rapidement. Dans le pétiole, l'évolution a éié intermédiaire. Au stade deux feuilles, les p plantes ayant été misese en lumiére continue aussitôt aprés le traitement, l'augmentation initiale des reserves glucidiques s'est à nouveau produite. Au contraire, dans l'obscurité continue, la diminution des glucides a été analogue chez les plantes témoins et chez les plantes traitées. Quant à la chlorophylle. la teneur a augmenté jusqu'au 4e jour aprés le traitement, puis elle a diminué ensuite en même temps que le saccharose tandis qu'apparaissaient des signes de chlorose. Il est suggéré QUE la disparition du saccharose pourrait provenir, soit d'une inhibition dc sa formation par manque d'ATP photosynthétique-2, soit de son hydrolyse, ce qui expliquerait l'augmentation initiale des oses. Biochemische Cesichispunkle zur Physiologie von Rettichen (Raphanus sativus L.) nach Simazinbekandllug I. Produktion von Gluciden Die Wirkung von Simazin beschränkt sich nicht auf die Hemmung der Photosynthese. In Rettichen (Raphanus sativus L.) verursachte Simazin am Anfang in den Blättern eine beträchtliche Abnahme an Gluciden. Diese Abnahme betraf hauptsáUhlich Glucose und Fructose und noch mehr die Saccharose; dabei trat gleichzeitig Glycerin auf. In den ersten drei Tagen nach der Behandlung nahmen in der Wurzel freie Zucker (Osen) und glykosidisch gebundene Zucker (Oside) zu, danach nahmen sie rasch ab. Im Biatlstiel lag die Produktion dazwischen. Wenn die Pflanzen im 2-Blattstadium unmittelbar nach der Behandlung Dauerlicht ausgesetzt wurden, wiederholte sich die anfängliche Zunahme an ‘glucidartigen’ Reservestoffen. Befanden sich aber die Pflanzen in ständiger Dunkelheit, entsprach die Abnahme an Gluciden der von den Kontrollen. Der Chlorophyllgehalt nahm his zum vierten Tag nach der Behandlung zu und sank dann gleichzeitig mit der Saccharose ab. wobei Anzeichen von Chlorose auftraten. Es liegt die Vermutung nahe, dass die Abnahme der Saccharose entweder mit der Hemmung der Saccharosebildung durch Mangel an ‘Photosynlhcsc-2′-ATP, oder durch ihre Hydrulyse zusammenhánget, was auch die anfängliche Zunahme an Osen erklären würde. Some biochemical aspects of the physiology of radishes (Raphanus sativus L.) treated with simazine I. Production of glucides The action of simazine is not limited to the inhibition of photosynthesis. In radishes (Raphanus sativus L.) simazine caused a considerable initial reduction in the amount of glucides in the leaf blades of treated plants. This reduction applied principally to glucose and fructose and still more to saccharose, while at the same time glycerol appeared. In the root, oses and osides increased over the first 3 days following treatment and then decreased rapidly. In the petiole, production was intermediate. At the two-leaf stage, when the plants were subjected to continuous light immediately after treatment, the initial increase in glucidic reserves was repeated. In continuous darkness, however, the decrease in glucides was similar in both controls and treated plants. The content of chlorophyll increased until the fourth day after treatment then it decreased at the same time as saccharose, while signs of chlorosis appeared. It is suggested that the disappearance of saccharose might be due either to its formation being inhibited through lack of ATP ‘photo-synthetic-2′. or to its hydrolysis, which would explain the initial increase in the oses.     

From carbon flux to regime shift

The basic assumption in biological oceanography – and in GLOBEC – is that physical forcing at a wide range of space and time scales determines most of the dynamics of marine populations. This has been very productive and provides the global context for GLOBEC and other programmes. How far can it take us in the future; and, alternatively, what role is played by community interactions?     

COMPARISON OF FLAT-PANEL DIGITAL TO CONVENTIONAL FILM-SCREEN RADIOGRAPHY IN DETECTION OF EXPERIMENTALLY CREATED LESIONS OF THE EQUINE THIRD METACARPAL BONE

Radiographic diagnosis of equine bone disease using digital radiography is prevalent in veterinary practice. However, the diagnostic quality of digital vs. conventional radiography has not been compared systematically. We hypothesized that digital radiography would be superior to film-screen radiography for detection of subtle lesions of the equine third metacarpal bone. Twenty-four third metacarpal bones were collected from horses euthanized for reasons other than orthopedic disease. Bones were dissected free of soft tissue and computed tomography was performed to ensure that no osseous abnormalities were present. Subtle osseous lesions were produced in the dorsal cortex of the third metacarpal bones, and the bones were radiographed in a soft tissue phantom using indirect digital and conventional radiography at standard exposures. Digital radiographs were printed onto film. Three Diplomates of the American College of Veterinary Radiology evaluated the radiographs for the presence or absence of a lesion. Receiver operator characteristic curves were constructed, and the area under these curves were compared to assess the ability of the digital and film-screen radiographic systems to detect lesions. The area under the ROC curves for film-screen and digital radiography were 0.87 and 0.90, respectively ( P =0.59). We concluded that the digital radiographic system was comparable to the film-screen system for detection of subtle lesions of the equine third metacarpal bone.     

An Economic Analysis to Aid the Marginal Decision on Rotation Length: I. Presentation of the Principle

This economic analysis of the rotation problem is based on theactual decision which the forest manager must make for everystand, i.e. whether to fell now or in five years or so. Thismarginal decision becomes important, and need only be carefullyconsidered, when the stand nears financial maturity. The marginalapproach is perhaps the most realistic approach to the problemof financial rotations. The financial decision is based uponthe recognized criterion of maximum net discounted revenue (N.D.R.)per unit total invested capital. Certain theories of productioneconomics are combined with the practical methods of forestvaluation. These principles are used to present the economicanalysis as a graphical choice of the rotation at which thecombined yield of pulpwood and sawtimber maximizes N.D.R. Finally,current product prices are introduced and the optimum rotationis found. These current prices may genuinely be assumed to beconstant for any particular five-year period. A subsequent paperwill develop the basic principle into a multi-product technique.The principle is presented essentially as a fundamental techniquefor the projects of forest economics: its application and useare considered here in general terms, and for a specific Sitkaspruce (Picea sitchensis) stand type. An instrument for therapid determination of financial rotation and N.D.R. has beendeveloped from this principle of rotation determination.     

The Changing Regional Structure of the U.S. Economy

This paper utilizes newly available industry-specific historical measures of Gross Regional Product to highlight the changing regional structure of the U.S. economy between 1963 and 1986. During this period, the percentage of U.S. output produced in the eight different regions changed significantly. The largest changes occurred in the Great Lakes (?3.65 percent), Mideast (?3.32 percent), and Southeast (+3.64 percent). Four major industry sectors (Agriculture, Mining, Construction, and Government) declined in relative importance in all eight regions. Five major industry sectors (TCPU, Retail Trade, Wholesale Trade, FIRE, and Services) expanded in relative importance. Somewhat surprisingly, Manufacturing output expanded for the U.S. as a whole and for six of the eight regions. The perception of decline in the relative importance of manufacturing in the U.S. is clearly based on the dramatic declines in the once dominant manufacturing base of the Mideast and Great Lakes regions.     

THE ROLE OF LONG-TERM EXPERIMENTS IN VALIDATING TRAIT-BASED APPROACHES TO ACHIEVING MULTIFUNCTIONALITY IN GRASSLANDS

Quantifying the relationships between plant functional traits and ecosystem services has been promoted as an approach to achieving multifunctional grassland systems that balance productivity with other regulating, supporting and cultural services. Establishing trade-offs and synergies between traits and services has largely relied on meta-analyses of studies from different systems and environments. This study demonstrated the value of focused studies of long-term experiments in grassland systems...