Ricerche Sui Fenomeni di Contrazione di Mitocondri Isolati di Internodio di Pisello

Abstract

Study on the contraction phenomena of isolated mitochondria of pea internodes. — The action of the phosphorylative inhibitors atractylate and oligomycin on ATP-induced contraction of isolated pea mitochondria has been studied. Oligomycin has proved to be an efficient inhibitor of mitochondrial contraction; no effect is seen on the contrary upon addition of atractylate. Both atractylate and oligomycin inhibit completely oxygen consumption of mitochondria with succinate as substrate. On the base of these results it is postulated that the two inhibitors act upon different sites of the phosphorylative reaction sequence.     

Fenomeni di Inattivazione e di Riattivazione Enzimatica in Endospermi di semi di Ricino

Abstract

Inactivation and riactivation of enzymes in endosperms of castor bean seeds. — On the basis of previous results, the possibility has been investigated of the reversible interconversion of active and inactive form of enzymes in castor bean seeds, during their development.

The results described here indicate that:

1. the activity of some glycolytic enzymes increases greatly (81% and 400% increase of, respectively, Gl-6-P-dehydrogenase and aldolase) upon incubation of dry seeds for few hours at 4 °C.

2. The decrease of enzyme activity upon dehydration of seeds and the increase during the subsequent imbibition can be shown reproducibly.

3. This same observation is made for oxygen uptake.

These results are interpreted to indicate the reversible inactivation of enzymes caused by dehydration of seeds.     

Tecniche di Coltura di Semi di Grano Sottoposti ad Operazioni di Trapianto Embrionale

Abstract

Cultural techniques for wheat seeds submitted to embryo transplantation. — The author, on the basis of his experience coming from the work carried out on the embryo transplantation for several years, takes in consideration some aspects, at technical level, regarding the best way to cultivate wheat seeds submitted to embryo transplantation operations.

In particular, the author refers on the possibility to sow the transplants just made (while the traditional method foresees the drying of transplants for 48–96 hours under laboratory conditions) and he illustrates the results of the transplant culture in jiffypots, which allow to improve survival of materials intended for the growth in field.     

Identificazione di Alcuni Fattori di Crescita Nel Succo di Pomodoro

Abstract

Growth-factors in tomato juice. Raw juice of green and red tomato fruits contains 7 amines which can be separated by paper electrophoresis. These were identified as basic amino acids (arginine, lysine and ornithine) and aliphatic diamine and polyamines (putrescine, spermine and spermidine). These amines were found in tomato juice for the first time. One compound (band 6, table 1) was not identified. Putrescine, spermidine and the unidentified band, after elution, were assayed « in vitro » for the possible cellular proliferation of Jerusalem artichoke (« Helianthus tuberosus ») dormant tubers. The results show that the last three coumpounds must be considered natural growth-factors present in the raw juice of tomato fruits.     

Ricerche Sull'ultrastruttura dei Tubi Cribrosi di Piccioli di Foglie di Edera

Abstract

The ultrastructure of sieve tubes in leaf petioles of HEDERA HELIX. — The structural organization of the sieve elements in Hedera leaf petiole at the beginning of the second year of life has been studied. At this stage of life the sieve tubes are completely developed, but still in full activity.

Their plasmatic structures, though altered, show that they are still alive. The cytoplasm forms a parietal layer; mitochondria, endoplasmic reticulum and plastids are present although very peculiar in aspect. The cytoplasm is bounded externally by a plasmalemma; on the contrary no tonoplast is detectable.

The data reported in this paper are favourable to the idea of an active partecipation of the sieve tubes in the translocation of organic solutes, in agreement with the findings concerning the oat coleoptile.     

Variazioni di Metaboliti Nel Seme di Ricino in Fase di Maturazione

Abstract

Changes of glycolytic substrates level during ripening of the castor bean seed. — The changes of the concentration of carbohydrates and of the main glycolytic substrates in the castor bean seed during the ripening phase were investigated. The following results were obtained:

The level of unphosphorylated sugars and of acid hydrolysable polysaccharides remains almost unchanged, with a tendency to a rise during the ripening phase. The slight increase of these compounds, together with the transition of the R. Q. from high to low values, might be interpreted as an indication of a shift of the seed from the a metabolism of fat synthesis to one of conversion of lipids into sugars, such as is observed in the germinating castor bean seeds.

Hexose monophosphate level sharply decreases during the last period of maturation. However, the level of these substrates does not fall so low as to suggest a severe limitation for the pentose-P pathway activity.

Fructose diphosphate, DOAP, GAP, 3 PGA, 2 PGA, PEP and pyruvate levels consistently increase during the ripening process. This indicates that the drop of oxygen uptake observed in this phase cannot be due to a lack of glycolytic substrates. On the other hand, the ratios between some substrates are shifted, during ripening, from values close to the theoretical equilibrium constants to quite different values. This finding, when correlated with the one of the strong decrease of the glycolytic flow, strongly suggests a severe inactivation of the glycolyting enzymes during ripening.

The increase of pyruvate in tissues showing a decreasing respiratory activity indicates a fall of the oxidative capacity of mitochondria. This might be due to a lack of ADP, or other high energy bond acceptor, following a block of synthetic processes. However, no decrease of ADP level, and an increase of the ADP/ATP ratio during ripening is observed, Among the alternative hypothesis: a) lack or excess of oxalacetate; b) increase of concentration of some Krebs cycle inhibitor; c) inactivation of mitochondrial enzymes, the latter is thought most probable, in view of the finding of a sharp decrease of some other enzyme activities during ripening, of the above mentioned interpretation of the shift of the ratios between glycolytic substrates, and of the very low level of mitochondrial activity in preparation from the mature castor bean seed. These results when correlated with those from parallel investigations on the biochemistry of castor bean seed maturation and germination suggest, as a working hypothesis, that the respiratory metabolic inactivation accompanyng seed repening is due to a general block of the metabolism of ribonucleic acid and thus protein synthesis.     

Fissazione di CO2 da Parte di Entomocecidi di Cuscuta Australis

Abstract

Fixation of carbon dioxide by galls of CUSCUTA AUSTRALIS. — The mechanism of the carbon dioxide fixation by Cuscuta is a controversial biochemical topic. Light induced reactions are involved in MacLeod's opinion while others as Ciferri and Poma believe that mainly a dark-fixation occurs.

In this study use is made of the galls, caused by the insect Smicronyx on Cuscuta australis, that appear more green coloured than the normal tissues.

Equal weights of excised galls were kept both in light and in darkness in contact with C¹⁴O₂for different incubation times, and the magnitude of the fixation was compared under these two conditions by measuring radioactivity of both soluble and acid hydrolysed fractions.

After short exposures to the tracer the fixation in light greatly exceeds that in dark (25–19/1) while with more prolonged exposures the ratio sharply decreases (to about 5/1): these figures can be interpreted with the assumption that a strong light-induced fixation superimposes itself to a low but definite dark-fixation activity.

The ratio does not change if radioactivity is measured in the hydrolysed fractions.

These results are of course referred to as being largerly preliminar and requiring further and more extensive studies.     

Sul comportamento di alcuni innesti di occhi nelle larve di Discoglossus pictus

Zusammenfassung Werden zwei primäre Augenblasen mit angefrischten Teilen derselben in Kontakt gebracht, so ordnen sie sich derartig an, daß die Elemente der einen Netzhaut sich mit denen der andern so gleichförmig vereinigen, daß keinerlei Diskontinuität zwischen den zwei in Kontakt befindlichen Netzhautportionen noch irgendwelche Veränderung nach Zahl und Beschaffenheit der Elemente selbst wahrzunehmen ist.Wenn die beiden Linsenblasen in Kontakt kommen, dann verschmelzen die beiden Portionen, durch die die Anlagerung erfolgt, miteinander und bilden eine Scheidewand, die sich nach und nach aufzulösen scheint. Die Fasern der einen und der andern Linse vereinigen sich schließlich zu einem Ganzen, wie wenn es sich um ein einziges Gebilde handelte.Die die Hornhäute der beiden Augen bildenden Elemente konvergieren zuerst gegen einen Punkt der vorderen Linsenkapsel, wohl entsprechend der Stelle, wo die Verlötung der beiden Linsenkapseln erfolgt; dann aber löst sich diese Verwachsung und die Zellen dehnen sich in einer einzigen Linie zur Bildung einer BrÜcke, welche von der skleralen HÜlle der einen Hälfte zu der der andern Hälfte zieht.Die Ciliarkörper- und Irisbildung erfolgt auf Kosten der zwei halben Augen, die in Kontakt kommen und sich zusammen zu einem einzigen harmonischen Ganzen entwickeln, als ob es sich um die beiden symmetrischen Abschnitte einer und derselben Augenblase handelte.Der Sehnerv wird ebenfalls durch Gewebsportionen gebildet, die zur Substanz der beiden Hirnblasen gehören, welche gleichfalls in der Weise verwachsen, daß sie eine Höhle umgeben, die das Produkt der Vereinigung der zwei Höhlen der beiden in Kontakt gekommenen Blasen ist.Und die Skiera? Und die Chorioidea?Auch sie scheinen dem allgemeinen, soeben angedeuteten Entwicklungsgesetz zn folgen. Es steht außer Zweifel, daß sich in diesem Fall sagen läßt, daß die mit angefrischten Partien in Kontakt gekommenen Augenblasen sich derart zu verhalten streben, daß sie ein einziges, die Portionen sowohl der einen wie der andern Augenblase umfassendes Auge bilden und daß diese Gewebe sich zu einem einzigen Organ ausbilden, das sich in der gleichen Weise entwickelt, wie wenn die Elemente nicht zwei verschiedenen Individuen, sondern nur einem Individuum angehörten.     

Studio di Sostanze Anticrescita di Origine Vegetale

Abstract

Antigrowth substances of plant origin. 1) A method for quantitative evaluation of antigrowth activity. The antigrowth activity of various kinds of plant extracts has been quantitatively evaluated, by determining the reduction of lenghtening of the lateral radicles of wheat grains induced by them. Grains are allowed to develop on water moistened filter paper until the lateral radicles have reached a lenght of about 5 mm.; then grains, carefully selected for approximately equal redicles lenght, are uniformly distributed in Petri dishes lined with filter paper, and moistened with 10 ml of distilled water, for the controls, or of the extracts under examination. All the operations are performed as much as possible under steril conditions. After 36 hrs incubation at 28° C, in the dark, the lenght of the lateral radicles is measured and the percent inhibition determined. This, when plotted against the log of the extract concentration, gives a straight line. The method is very sensitive and its reproducibility makes it possible to follow quantitatively the purification of antigrowth principles.     

Metabolismo di Quiete e Metabolismo di Crescita

Summary

The changes in carbohydrate and phosphorus metabolism of tomato ovaries stimulated to growth by pollination or auxin treatment found in previous studies prompted an investigation of the enzymatic systems concerned. In this research, the effects of pollination and of auxin treatment on phosphorylase and on phosphatase activity were studied. Phosphatase splitting inorganic P from adenosine triphosphate was characterized as different from that acting on glycero- and hexose-phosphate by the difference in inhibition by beryllium and fluoride.

Two phases of growth occurring during the earlier stages of fruit development were clearly defined by the behavior of the enzymes considered. During the first (induction) phase both phosphomonoesterase and ATP-ase activity markedly dropped. This was followed by a marked rise in activity during the later stages of growth.

Phosphorylase activity, unlike that of the phosphatases, showed no relationship to the two phases of growth, and increased steadily during the period of observation. This agreed with the rate of starch synthesis observed in the growing auxin treated or pollinated tomato fruits.

Changes in the activity of these enzymes in the not pollinated, not auxin treated ovaries during the period of observation were, on a comparative basis, very small.     

Assunzione di Fosforo32 da Parte di Cuscuta Epithymum Parassita di Trifolium Repens

Abstract

Uptake of Phosporus-P³² by CUSCUTA EPITHYMUM parasitic of TRIFOLIUM REPENS. — Filaments of C. epithymum, parasitic on T. repens, partially immersed in a solution containing KH₂P³²O₄, uptake from the host solely, or mainly, radioactive ortophosphate. Radioactive hexose phosphates and radioactive nucleotides present in the extracts prepared from C. epithymum, appear to be the result of the metabolization by the dodder of the orthophosphate uptaken from the host.     

La Posidonia oceanica: problemi di ecologia,di funzionamento e di biologia

Abstract

The functional roles of seagrasses in the economy of coastal waters are to be fully realised and more clearly delineated. The biology, ecology and energetics of seagrasses meadows of the Mediterranean Sea, and in particular of Posidonia oceanica inclusing the stabilization of coastal sediments, this role as a base for major detrital food chains, nutrient resources contributory to general productivity of the open sea and the support of dense epiphytic communities, are discussed.     

Analisi polliniche di fanghi di acquitrini della Pania di Corfino,nell'Appennino Lucchese

Abstract

Pollen analysis of the sediments of a bog on the slopes of Panià di Corfino (Apennines, near Lucca). Fossil pollens in the sediments of a bog situated on the slopes of Pania di Corfino (Lucca) have been studied. The site studied lies on oligocenic rocks and is surrounded by beeches.

From a depth of 120 cm up to 50 cm the prevailing pollens belong to species typical of beech and silver-fir woods. Layers from 50 to 25 cm contain mostly pollen of herbaceous plants and of Ericales shrubs, especially belonging to the genus Vaccinium. The upper layers (25 to 5 cm) show a prevalence of Pinus mugo pollen. These data suggest that, after a long period during which climatic conditions resembled those of the present, a shift to a colder climate lowered the upper limit of the beechwoods.