Search

An arabino 4- O -methyl glucurono xylan has been isolated as the dominant form of the hemicellulosic material of the youngest internodes of Arundo donax . The polysaccharide contained d -glucose, d -xylose and l -arabinose in the molar ratios of 0·1:9·2:0·66, respectively, with a uronic acid content of 4·5%. Methylation and periodate-oxidation showed that the xylan has a β-1 → 4-linked xylose backbone and a degree of polymerization ca. 63. The xylan is very similar to that found in the mature tissues.

(1974). Mineral Element Composition of Cereal Grains from Different Growing Areas in Finland. Acta Agriculturae Scandinavica: Vol. 24, No. 4, pp. 327-334.

This paper reports further observations on microbodies in bean rust sporelings suggesting that the organelles correspond to glyoxysomes in higher plants. However, cytochemical tests for catalase (DAB-technique) gave negative results.

Variation in cytokinin supply has different effects on protein formation and enzyme development in primary leaves and coleoptiles of rye seedlings. The accumulation of enzyme activities, localized in different cell compartments of the leaves, responds with different sensivities. (1) In developing primary leaves of dark-grown rye seedlings total protein content and the activities of several enzymes are decreased by lowering the cytokinin supply by excision of the roots. Higher activities are again restored by application of kinetin to plants previously deprived of their roots. However, the activities of the photosynthetic enzymes so far investigated, and of the microbody enzymes, glycolate oxidase and hydroxypyruvate reductase, show a much more marked response to changes in the cytokinin level than either the total protein content or the activities of glucose-6-phosphate dehydrogenase or of the mitochondrial enzymes fumarase and cytochrome c oxidase. (2) In the coleoptiles of rye seedlings, light drastically enhances the breakdown of total protein and the decrease of all enzyme activities measured. By contrast to the behavior of primary leaves, total protein formation and the accumulation of all enzyme activities measured are strikingly prolonged after root excision which was expected to result in a lowered cytokinin supply. Subsequent addition of kinetin enhances the decay of protein and most of the enzyme activities determined and thus, in a similar way to the effect of light, seems to promote the senescence of the coleoptiles.

Der uberwiegende Teil der Fettsauren in der Knolle, bezogen auf die Gesamtmenge der erfassten Fettsauren, besteht aus Palmitin-, Stearin-, Linol- und Linolensaure. Uberdurchschnittlich hoch liegt der Olsaureanteil in Keimen und der Palmitinsaureanteil in Kronenregionen. Auffallend niedrig der Gehalt an Stearinsaure in Keimen, sowie der an Linolensaure in Kronenregionen.

The activity of the inorganic pyrophosphatase from isolated spinach (Spinacia oleracea L.) chloroplasts is strongly dependent upon the addition of magnesium ions. Since the complex of the bivalent ion with inorganic pyrophosphate is the real substrate, a definite Mg(2+)/Na4P2O7-ratio is required for maximum activity. When the activity was measured in particle-free extracts from chloroplasts, this ratio was shown to be approximately 3. However, an increase up to 10 was observed in the presence of thylakoid membranes. Furthermore, the kinetics in the presence of broken chloroplasts becomes sigmoidal.The altered kinetics have been shown to be due to starch located in the thylakoids. The inhibitory effect is caused by amylose alone but not by amylopectin., Detailed kinetic analysis of the inhibition showed no influence of amylose on the Hill-coefficient. Since ethylenediaminetetracetic acid was shown to have similar effects as amylose, starch might regulate the pyrophosphatase activity by binding Mg(2+)-ions.

Anhand mikroskopischer Untersuchungsbefunde wird ein beiFagus sylvatica L. vereinzelt auftretender Holzfehler beschrieben und auf das Vorkommen anomal breiter Strahlen zuruckgefuhrt. Das besondere Verhalten extrem breiter Holz- und Rindenstrahlen ermoglicht den Einschlus von Dilatationsgewebe und sklerotischen. Elementen im Holz der das beschriebene Holzfehlerbild erklaren kann.

Two inorganic pyrophosphatases (pyrophosphate phosphohydrolase, E.C.3.6.1.1) have been identified in spinach (Spinacia oleracea L.) leaves. The two isoenzymes were readily separated by polyacrylamide gel electrophoresis and by isoelectric focusing between pH 4 and 6. One isoenzyme is located in the chloroplasts whereas the other form was isolated from the soluble "cytoplasmic" fraction. In addition, a third form appeared when the isolation procedure started from a crude extract from whole leaves. It is suggested that this form represents an aggregation between the two natural species.The three forms differ in their kinetic properties, such as substrate affinity and pH optima. The apparent K m values were determined to be 10(-5)M for the chloroplastic isoenzyme, 7×10(-5) M for the "cytoplasmic" isoenzyme and 3×10(-5) M for the third form. At limiting Mg(2+) concentrations, the corresponding pH optima were found to be 8.55, 8.95 and 8.75, respectively.

Phospholipids and glycolipids of rust-infected leaf halves and uninfected halves of the same leaves were quantitatively determined and compared with the lipids of healthy primary leaves of bean plants. The phosphatidyl-choline, phosphatidyl-ethanolamine, phosphatidylinositol and sulphoquinovosyl diglyceride (SL) content of the infected halves was the same as in the control plants. The infected tissue showed a decrease in monogalactosyl diglyceride (MGG), digalactosyl diglyceride (DGG) and phosphatidyl-glycerol (PG) and an increase in phosphatidyl-serine (PS) and phosphatidic acid content. These differences were localized mainly in the region of the pustule and not in the surrounding mycelium-free tissue. The amount of all phospholipids and glycolipids in the uninfected leaf halves was slightly lower than in the controls. The ungerminated and germinated uredospores of the parasite contained no MGG, DGG, SL or PG. The infected half leaves showed an increase in 32P incorporation into all phospholipids especially into PS. The differences in 32P-incorporation between the phospholipids of the uninfected half leaves and the controls were only small. These results were discussed in relation to permeability changes of rust-infected bean tissue.

Summary Autotrophic cells of Chlamydomonas reinhardii and Chlorella pyrenoidosa , cultured in blue light, have a significant higher content of phosphate compared with cells cultured in the red light with equal dry mass. The greatest effect was observed in the acid-insoluble polyphosphates. The blue light-dependent enhancement was less pronounced in the acid insoluble stable and the acid soluble labile phosphate. In conditions of nitrogen deficiency the polyphosphates contain nearly all the phosphate additionally incorporated in the blue light. The enhancement of 32 P-incorporation, compared with the red light, is delayed and more distinct after about 30 min. Blue light cells have a higher content of ATP. The interaction between the blue light-dependent increase of the ATP- and polyphosphate pool is discussed.

International audience

Peroxidases oxidizing indoleacetic acid (IAA) are present in the resting grains of barley, rye and wheat. The grains also contain small molecular inhibitors of the enzymes. A partly purified preparation of barley seed proteins was shown to contain at least two IAA oxidases about pI 5 and pI 10, mol. weight 30,000 and with a pH optimum 5.1–5.7. The enzymes require Mn2+, 2,4-dichlorophenol and orthophosphate for the maximum activity. Attempts to separate IAA oxidase and peroxidase activities of the enzymes were unsuccessful.

Summary The dynamic model of the daily height increment of plants, presented in 1970 (Hari et al.) has been developed further. The growth rhythm of four tree species has been analyzed with the help of more extensive material. Air temperature proved to be the most dominating environmental variable, determining 75-96 per cent of the variation in growth. The possibilities of applying the model in genetic studies and time-growth analyses are discussed.

The crude homogenate of cells from Chlamydomonas reinhardii was placed on a linear gradient from 30% to 60% sucrose and centrifuged for 4 hours at 60 000 g. After fractionation of the gradient the distribution of enzymes was determined. Hydroxypyruvate reductase and glycolate dehydrogenase, two markers for peroxisomes, appeared with one sharp peak at density 1.185 g/cm(3) within the gradient. Twenty-five percent of the hydroxypyruvate reductase was particulate and 75% was found as solubles in the top fractions. The peaks of both enzymes matched exactly the peak of the cytochrome oxidase which is a marker for mitochondria. The profile for malate dehydrogenase was the same as that for hydroxypyruvate reductase. Catalase, however, showed two peaks. One coincided with the peak of cytochrome oxidase and the other appeared at density 1.22 g/cm(3). More than 50% of the catalase moved into the gradient during centrifugation.

The activities of trypsin inhibitors and Aspergillus-proteinase inhibitors have been assayed in barley embryos germinating in different conditions. The Aspergillus-proteinase inhibitor activity increased about 20-fold during 6 days at 20°C both in separated embryos germinating on nutrient agar and in the embryos of undissected grains germinating on agar with or without mineral salts. Significant inhibitor activity was also present in root tips at later stages of vegetative growth. Whether any changes occurred in the molecular weight distribution of the inhibitors present in the seedlings was studied by gel filtration on Sephadex G-75; only minor changes were observed. The trypsin inhibitor activity per seedling remained roughly constant in all cultures. In gel filtration experiments all the activity appeared to be due to the inhibitor species present in resting embryos.

Zur Angleichung an die Verhaltnisse am naturlichen Standort wurden absolute Reinkulturen vonUtricularia exoleta in mineralischer Nahrlosung mit toten Daphnien „gefuttert”, die vorher im Autoklav sterilisiert worden waren.

Es wurde eine verbesserte Methode zur Trennung und quantitativen Bestimmung von organischen Sauren beschrieben, die bei Aufarbeitung pflanzlichen Materials zum Einsatz kam und die fur die Bestimmung von Sauren in Fruchten besonders geeignet scheint. Folgende Sauren konnten mit dieser Methode bisher getrennt werden

The effects of a non-ionic detergent. Triton × 100, on protoplasmic streaming in some plant cells, on plasmolysis, and on leakage of solutes from beet cells were investigated. The results of the different tests showed some features in common: (1) There is a critical range between 0.007 and 0.01 % v/v. (2) Above this concentration of the surfactant, that is at a concentration close to 0.01 %, the effect is manifested in the following ways. Plasmolysis with sucrose is anomalous or impossible. Protoplasmic streaming ceases within a short time. Definite leakage of ions and sugars starts from beet tissues. (3) At concentrations lower than 0.01 to 0.007 % there is enhanced retention of solutes in beet disks. — It is thought that the critical micelle concentration is of paramount importance. The micelle effect may consist in solubilizing or in forming mixed micelles or a complex with the globular lipoprotein units of the outermost plasma layer, the plasmalemma. The effect of the lower Triton concentrations is discussed.

In Erganzung fruberer Untersuchungen wurden von methacrylat-eingebettetem Zugholz- und Normalfasergewebe vonPopulus euramericana cv.regenerata ultradunne Quer- und Langsschnitte hergestellt. Die elektronen-mikroskopische Untersuchung zeigt, das die Zellwand der Zugholzfaser aus Mittellamelle, Primarwand, den Sekundarwandschichten 1 bis 3 sowie einer Immenseitigen Abschluslamelle besteht. Die S3 stellt dabei die fur Zugholzfaser charakteristische gelatinose (G-)Schicht dar. Die Struktur dieser G-Schicht kann elektronenmikroskopisch nur durch Herauslosen des Einbettungsmediums deutlich sichtbar gemacht werden. In solcher Weise behandelte Ultradunnschnitte lassen erkennen, das die G-Schicht eine Wabenstruktur besitzt, in der einzelne cellulosische Lamellen durch Haftpunkte miteinander verbunden sind. Wahrscheinlich sind die Kammern des Wabensystems mit quellbaren Interlamellarsubstanzen ausgefullt, die in Verbindung mit der Wabenstruktur die bekannten Langszugspannungen im Zugholz verursachen konnten. Die Entstehung dieser Spannungen ist sowohl als Folge einer Quellung, wie auch als Folge einer Entquellung der G-Schicht denkbar. Die Moglichkeit von Strukturveranderungen durch die angewendeten Praparations vefahren wird ausfuhrlich erortert. Es wird nachgewiesen, das die beschriebeue Wabenstruktur der G-schicht nicht den wabigen Strukturen entspricht, die sich durch Saurebehandlung in der zentralen Sekundarwandschicht normaler Faserzellen erzeugen lassen.

Spektralbereiche in den Blattern zu einer erheblichen Verschiebung in der Zusammensetzung kommt (Voskresenskaja 1952, Appleman u. Pyfrom 1955, Howell et al. 1957, Voskresenskaja u, Grischina 1958). Die einzelnen Autoren haben dabei ihre Anzuchten nicht nur mit verschiedenem Versuchsmaterial, sondern auch bei unterschied lichen Bestrahlungsbedingungen vorgenommen. So wurde mit energie gleicher, quantengleicher und produktionsgleicher Strahlung gearbeitet. Trotz dieser methodischen Unterschiede und der nicht identischen

SummaryMeasurements are reported on the influence of mulch on the chemical and physical characteristics of the soil and the chemical composition of the crop, together with growth measurements on an indicator crop in the greenhouse and on mature coffee in the field. Mulch reduced soil acidity; increased organic carbon, Kjeldahl nitrogen, exchangeable potassium and available phosphorus; and decreased exchangeable calcium and manganese. It increased total pore space, free-draining pore space and rate of rainfall acceptance in the top soil. Effects on the coffee were to increase phosphorus, potassium and in some cases nitrogen in the leaf, but reduce magnesium and calcium levels. Potassium and calcium levels were increased in feeder roots, whereas in the ripe cherry the phosphorus level was increased but nitrogen, calcium and magnesium levels were reduced. The soil effects were reflected in increased growth of the indicator crop and mulch improved the growth of the coffee tree in a year of seasonal drought.

1. Durch plotzliche Verringerung der Zelldichte (Suspensionsverdunnung) wurde in Anzuchten eines Stammes von Chlorella pyrenoidosa, die durch Licht-Dunkel-Wechsel synchronisiert waren, eine Blockierung der Zellteilung herbeigefuhrt. 2. Die Starke dieses Verdunnungseffekts hangt von dem Entwicklungszustand der Zellen ab. Junge Zellen bleiben unbeeinflust, bei ausgewachsenen Zellen kann die Hemmung mit Ubergangen bis zum totalen Absterben fuhren. 3. Durch Verdunkeln kann die Wirkung einer Verdunnung unter bestimmten Umstanden wieder aufgehoben werden. 4. Verdunnung im Blaulicht fuhrt zur Hemmung der Zellteilung, wahrend im produktionsgleichen Rotlicht kein Verdunnungsschock eintritt. 5. Die beobachteten Hemmeffekte werden in Verbindung mit Problemen der Synchronisierung erortert.

Among the many endogenous compounds implicated in the induction of cutaneous photosensitization, none have aroused more clinical interest than the porphyrins. From recently obtained information about these compounds a new understanding of light-provoked hypersensitivity reactions is gradually emerging. Abnormalities of porphyrin metabolism, not previously suspected to be present (1—5), are being found in patients whose skin responds to moderate amounts of ultraviolet energy with formation of the characteristic lesions of polymorphic photodermatitis, i.e., macules, papules, plaques, wheals, vesicles, and eczematous dermatitis. It is possible that partial genetic blocks may cause abnormalities of porphyrin metabolism. The hereditary nature of abnormalities of porphyrin metabolism has been ascertained in several genetically distinct forms of porphyria that are manifested by cutaneous photosensitivity. Such abnormalities of porphyrin metabolism would seem to be associated with decrease or increase of enzyme activity at different stages in the pathway of porphyrin biosynthesis. Identification of the types of porphyrin present in the various tissues and organs of the body constitutes an effective means of exploring the site and character of these metabolic abnormalities. The development of cutaneous photosensitivity in porphyria has been attributed to the presence of excess quantities of porphyrin in erythrocytes, plasma, skin and other tissues. Accurate determinations have been made of the amounts of porphyrin normally present in the urine, feces, crythrocytes, liver and bone marrow of man and laboratory animals (6), but little has been learned about the amount and type of porphyrins normally present in the skin of man. In order to understand the nature

The growth of Atropa belladonna cv. lutea Doll cells and the activities of several enzymes were studied as a function of time in suspension cultures without added auxin, with α-naphthaleneacedc acid (NAA) and with α-naphthoxyacetic acid (NOA). The growth curves were rather similar and therefore easy to compare. The enzyme activities (per mg dry weight of culture) were distinctly higher in cultures grown with NAA than in the other two treatments, in which root formation was common. In some cases the enzyme activities were lower in cultures with NOA than in the control series but usually the curves were quite parallel. Promotion of enzyme activities by NAA (aldolase, aminopeptidase, gluta-mate: oxaloacetate transaminase) was clearest in the beginning of the phase of rapid cell division (6-day-old culture). These three enzymes reach their maxima at this stage of growth in the other series as well. Ribonuclease activity increased in the stationary phase cells (13 and 19 days) with NAA but with the other treatments the level of this activity was relatively stable. Peroxidase and phosphatase did not show any characteristic maxima, glutamate: pyruvate transaminase activity was low and no amylase activity could be demonstrated. The results indicate that synthetic plant growth substances can regulate the physiological state of a tissue by causing alterations in enzyme activities, but their action is clearly specific.

Es wurde der Einflus radioaktiver Strahlungen auf die Richtungsbewegungen beiPharbitis hispida beobachtet und festgestellt, das die Pflanze auf einseitige dauernde Bestrahlung deutlich radiotropisch reagiert. Die radiotropische Reaktion besteht aus einer positiven und einer negativen Krummung, deren Intensitat sich umgekehrt proportional zur Intensitat des Radiumpraparates verhalt.

1. The order of magnitude of the incorporation of uridine into RNA within 15 min is comparable in normal synchronous, N-deficient, and recovering cultures of Chlorella pyrenoidosa. 2. The kinetics of the incorporation of uridine into RNA show the kind of curves to be expected from the theory for systems with several products or several compartments. 3. When the cultures are treated with rifampin or chloramphenicol, uridine incorporation is much more inhibited in normal cells than in N-deficient cells, while treatment with cycloheximide has only slight effects in both cases. 4. In N-deficient and recovering cultures, 3H-uridine activity can be shifted by chase treatment from ribosomal precursors to 80S ribosomes (in contrast to normal cultures where it can be shifted to 70S ribosomes). 5. Particles isolated from a membrane-rich cell fraction by DOC treatment are labelled much more quickly by 3H-uridine in N-deficient than in normal cells. 6. Under conditions of nitrogen deficiency, uridine incorporation into chloroplastic ribosomal particles is not so greatly preferred as it is in Chlorella under normal conditions. Consequences of these results are discussed which concern the control of ribosome synthesis in Chlorella.