EinAdoxus vitis-Herd

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Biochemical mutants in higher plants as tools for chemical and physiological investigations — A survey

Summary A report is given on biochemical mutants in higher plants with emphasis on metabolic mutants. Since the discovery of thiamine-defective mutants inArabidopsis thaliana andLycopersicon esculentum some other mutants in different species became available. The first higher plant with an absolute requirement for an amino acid is a proline-deficient mutant inZea mays. Inchloronerva ofLycopersicon esculentum synthesis of nicotianamine is blocked. This is the first instance where a hitherto unknown function is attributed to an already known compound by work with a mutant of higher plants. Nicotianamine is distributed throughout all vascular plants and appears to be linked with short-distance iron transport. The wilty mutantflacca inL. esculentum lacks abscisic acid with some consequences to different parts of metabolism. In the same species the mutant T 3238btl/btl, fer/fer carries two separate, independent mutations which affect the transport of boron and iron, respectively. Selection for chlorate resistance led to the discovery of mutants with impaired nitrate reductase activity and nitrate uptake inArabidopsis thaliana and in consequence added new information to our knowledge of the regulation of nitrate assimilation. Other mutants of similar kind were detected inNicotiana tabacum andHordeum vulgare. Mutants with defects in the photosynthetic system were discovered inZea mays andHordeum vulgare. Plastome mutants inOenothera revealed a lack of ribulose-1,5-biphosphate carboxylase activity and showed interference between the genetic system of the plastids and that of the nucleus.The search for new mutations should be continued by different techniques, whereby the chance to find auxotrophic mutants by grafts should not be overlooked.

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Biochemische Mutanten höherer Pflanzen als Objekte für chemische und physiologische Untersuchungen. Eine Übersicht

Zusammenfassung Es wird über biochemische Mutanten höherer Pflanzen unter besonderer Berücksichtigung von Stoffwechsel-Mutanten berichtet. Seit der Entdeckung von Thiamin-Mangelmutanten beiArabidopsis thaliana undLycopersicon esculentum sind einige andere Mutanten verschiedener Arten bekannt geworden. Die erste höhere Pflanze mit einem absoluten exogenen Aminosäure-Bedürfnis ist eine Prolin-Mangelmutante vonZea mays. Inchloronerva vonLycopersicon esculentum ist die Synthese von Nicotianamin blockiert. Dieses ist der erste Fall, bei dem durch Untersuchungen an der Mutante einer höheren Pflanze Aufschluß über die Funktion einer bereits bekannten, hinsichtlich ihrer biochemischen Rolle aber noch unerforschten Verbindung gewonnen werden konnte. Nicotianamin ist wahrscheinlich in allen Gefäßpflanzen vorhanden und steht dort mit dem Eisen-Nahtransport in Beziehung. Die Welke-Mutanteflacca vonL. esculentum produziert keine Abscisinsäure, was Auswirkungen auf verschiedene Richtungen des Stoffwechsels hat. In der gleichen Species trägt die Mutante T 3238btl/btl, fer/fer gleichzeitig zwei verschiedene, voneinander unabhängige Mutationen, die den Bor- bzw. den Eisentransport betreffen. Selektion auf Chlorat-Resistenz führte beiArabidopsis thaliana zur Entdeckung von Mutanten mit blockierter Nitratreduktase-Aktivität und verminderter Nitrataufnahme. Untersuchungen mit diesen Formen erbrachten neue Vorstellungen über die Regulation der Nitratassimilation. Ähnliche Mutanten wurden auch beiNicotiana tabacum undHordeum vulgare gefunden. Mutanten mit defektem Photosynthese-System sind beiZea mays undHordeum vulgare bekannt. Eine Plastom-Mutante vonOenothera zeigt einen Synthese-Block im Hinblick auf Ribulose-1,5-biphosphat-Carboxylase, der sich auf beide Untereinheiten auswirkt, so daß Wechselwirkungen zwischen dem genetischen System der Piastiden und dem des Kernes angenommen werden müssen.

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Prioritization of ground water contaminants and sources

The objective of this research was to identify chemical, physical, bacteriological, and viral contaminants, and their sources, which present the greatest health threat in public ground water supplies in the USA; and to classify (prioritize) such contaminants and relative to their health concerns. The developed contaminant prioritization methodology was based on frequency of occurrence and adverse health effects. Adverse health effects were based on carcinogenic potency, toxicity, hazardous chemical priorities and drinking water standards. Application of the methodology for wellhead protection areas, (WHPAs) revealed that approximately 200 different contaminants have been detected in the nation's public ground water supplies. The seven chemical constituents with the highest priority were arsenic, chromium, cadmium, carbon tetrachloride, chloroform, 1, 1-dichloroethylene, and ethylene dibromide. Other contaminants of concern were trichloroethylene, nitrates, barium, 1,1,1-trichloroethane, benzene, tetrachloroethylene, selenium, lead, toluene, mercury, gross alpha radiation, methylene chloride, coliform bacteria, metolachlor, metribuzin, 1, 1, 2, 2-tetrachloroethane, dibromochloroethane, simazine, radium-266, and toxaphene. The contaminant source prioritization methodology was also based on frequency of occurrence. Over 30 categories of sources were evaluated, with the eight with highest priority including agricultural activities, hazardous waste sites, landfills, industrial operations, septic tank systems, oil and gas field activities, urban land use, and underground storage tanks.