Osservazioni prellminari sul meccanismo di azione della cocliobolina

Abstract

MECHANISM OF COCHLIOBOLIN ACTIVITY: A PREVENTIVE NOTE. — Coch-liobolin caused leakage of phosphate and organic compounds from corn rootlets and potato discs, at room temperature. The leakage does not occur at 1–5°C, but when potato discs are incubated at this temperature and then thoroughly washed and brought at 25°C, a sharp increase of phosphate may be noticed in the incubation solutions.

Cochliobolin inhibited partially the aerobic respiration of glucose and endogenous carbon in Micrococcus pyogenes var. aureus resting cells. Aerobic respiration of pyruvate, succinate, fumarate and malate was completely inhibited, while the inhibition of lactate and Lketoglutarate respiration required a short lag period. The hydrogen-ion concentration of the media seemed to be an important factor controlling the rapidity of action of the inhibitor, because at pH 4 and 5 at least 120 minutes were required prior any effect could be observed, while only 30 minutes were required at pH 6.

The effects of cochliobolin on Micrococcus resting cells were irreversible In contrast, respiratory activities of acetonic powders were refractory to the substance under aerobic conditions, and oxidation of pyruvate, malate, fumarate, succinate and α-ketoglutarate were not affected by saturated solutions of cochliobolin. It is suggested that the first site of attack is the cell wall-cell membrane unit, altering cell permeability, so that inorganic ions and other cofactors essential to respiration are lost in consequence of the leakage through the cell membrane.     

Sul meccanismo di azione antimitotica della colchicina

Abstract

ON THE MECHANISM OF ACTION OF COLCHICINE ON MITOSIS. — The effect of colchicine on glutathione has been studied in order to explain its effect on mitosis. The results are consistent with the hypothesis that colchicine or its derivatives (colcemide) exert their antimitotic action by reversible oxidation of thiolic proteins present in the cell. This hypothesis could also explain the lack of antimitotic action of thiocol-chisode.     

Ricerche sul meccanismo di azione della cocliobolina B: effetti sul metabolismo ossidativo di Micrococcus pyogenes var. aureus

Abstract

STUDIES ON MECHANISM OF COCHLIOBOLIN ACTIVITY. B: EFFECTS ON OXIDATIVE METABOLISM OF MICROCOCCUS PYOGENES VAR. AUREUS. — Endogenous respiration of washed 24-hours old cells of Micrococcus pyogenes var. aureus was markedly decreased by cochliobolin, which also completely prevented pyruvate, succinate, fumarate and malate oxidation. The toxin inhibited also lactate and α-ketoglutarate utilization by Micrococcus cells, while aerobic respiration of glucose was only slightly reduced, and anaerobic breakdown increased. These phenomena were irreversible, and depended upon the pH of media and the lenght of incubation periods. In contrast, respiratory activities of cell-free homogenates and acetone powders of Micrococcus were refractory to the toxin, and the oxidation of Krebs cycle intermediates was not affected. These phenomena suggest that, although cochliobolin prevens the respiratory metabolism of Micrococcus cells, the initial locus of interference probably is not one of the common respiratory enzimes, but cell permeabiltiy. Thus, if one postulates that the toxin disturbs cell membrane integrity, by disrupting lipoprotein of phospholipid costituents, then the phenomena might be explained by the reduced concentration in the cells of cofactors essential to respiration, due to leakage through the cell membrane.     

Ricerche sul meccanismo di azione della cocliobolina. A: effetti della tossina su fettine di tubero di patata in riposo

Abstract

STUDIES ON MECHANISM OF COCHLIOBOLIN ACTIVITY. A: EFFECTS OF THE TOXIN ON FRESH POTATO TUBER SLICES. — Cochliobolin, a toxic compound produced by Helminthosporium oryzae, causes inorganic phosphorus leakage from fresh potato tuber slices, higher amounts being found in incubation media with higher toxin concentrations and for longer incubation periods. Organic compounds, also, are released by potato tuber slices, like phenolic products, large amounts of sugars, and some aminoacids, alanine, lysine, tyrosine, valine and γ-aminobutirric acid, which have never been observed in the incubation meida of untreated slices. Cochliobolin uptake by fresh potato tuber slices does not take place actively or, anyhow, at a metabolic level. Indeed, neither 2,4-dinitro-phenol (at concentration, pH, and incubations periods apt to reduce active uptake), nor low temperatures (0–2°C) prevent toxin uptake. Potato tuber slices are not affected by cochliobolin, unless kept at 25°C, and this fact suggests that while toxin uptake does not interest metabolic pathways, it might affect some phase, or structure, essential to cell metabolism. The locus of toxin activity seems therefore to be identified with its influence on cell absortion and retention activities, of products essential for metabolic processes. Thus the impairing of cell permeability, possibly affecting the processes or the structures which regulate the active uptake, seems to be, at the moment, the only evident interpretation of the phenomena observed.     

Effetto della cocliobolina sul trasporto attivo del sodio nella pelle isolata di Rana esculenta

Abstract

INFLUENCE OF COCHLIOBOLIN ON ACTIVE TRANSFER OF SODIUM ACROSS THE ISOLATED FROG SKIN. — Previous papers reported the hypothesis that the first site of attack of cochliobolin on plant materials is probably the cell membrane. Indeed, an impairement of cell permeability, possibly disrupting the processes and the structures which regulate the active adsorption, appears as the common origin of all the phenomena observed. A study of the effects of cochliobolin on net active transfer of sodium across the isolated frog skin might therefore help to elucidate the mechanism of action of the toxin. Esperiments carried on with this aim, showed that over a range of cochliobolin concentration from 30 to 0,2 μg/ml, the net transfer of sodium is markedly promoted during the first 60–90 minutes. Moreover, with intermediate concentrations, a first increase of sodium transfer is followed by a second larger one. These informations cannot yet be readily rationalized; however they offer further evidence that an interference with active adsorption, presumably acting on the cell membrane activity, must be regarded as the first locus of cochliobolin mechanism of action.     

Analisi informazionale degli schemi di dinamica della vegetazione. Un esempio sul popolamento vegetale delle dune del litorale di Venezia

Abstract

A method to quantify the dynamic schemes of vegetation based on information functions.—The dynamic schemes of vegetation as proposed by Braun-Blanquet have been never quantified with the aim to give indirect measures of the probability of transition between the types. This work presents a method that quantifies the arrows between the types by means of a redundancy measure. This is calculated by comparing the phytosociological types two by two. Redundancy, as proposed here, measures the similarity between the tables not only based on species composition but also on the basis of species cooccurrence. The method relies on the assumption that in a succession the higher is the redundancy between the types, that are presumably in sequence, the higher is the probability and then the velocity of transition from one type to another one. An example is given with data from coastal dune grasslands of the Venice Lagoon.     

Epidemiologia delle allergopatie respiratorie nella provincia di La Spezia

Riassunto è stato condotto uno studio su un gruppo di 296 pazienti affetti da atopia respiratoria residenti nella provincia di La Spezia. I soggetti erano sottoposti a prick test e/o RAST. Veniva considerata l'incidenza dei singoli allergeni. Dai dati emerge l'importanza delle Graminacee quali maggior responsabili di sensibilizzazioni al contrario di altre zone della Liguria ove è predominante la Parietaria.

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Summary In the present investigation 296 patients with respitatory atopy, resident in La Spezia have been studied. The diagnosis was estabilished on the basis of prick test and RAST. We evaluated the incidence of each allergen. We reported the aetiological importance of Grasses in La Spezia, whereas Parietaria is less predominant.

     

Ricerche sulle concentrazioni aeropolliniche diCupressaceae ePinaceae nell'atmosfera di Cagliari e considerazioni sul loro potere allergizzante

Riassunto Scopo della Ricerca è quello di stabilire le concentrazioni aeree periodiche dei pollini diCupressaceae ePinaceae rilevate nell'atmosfera di Cagliari e accertare l'esistenza di correlazioni tra queste e le sindromi allergiche manifestantesi nel periodo invernale-primaverile. Su un campione significativo di 1000 pazienti, di sesso ed età diversa, sono risultati sensibilizzati ai pollini di pini, tuie, cipressi e cedri 141 soggetti. Dalle indagini allergologiche non traspare tuttavia chiaramente il ruolo etiologico delleCupressaceae ePinaceae per le quali peraltro non si sono riscontrate mai monosensibilizzazioni. I campionamenti aeropollinici hanno permesso di identificare alcuni aspetti fenogici ed actupalinologici utili per meglio interpretare i bioritmi delle due famiglie anche in funzione degli agenti climatici.      

Aerobiologia in Italia e considerazioni su alcune specie vegetali allergeniche nella provincia di Ferrara

Sommario E' del 1974, sulla traccia fornita dall'International Biological Program, che è in atto nel nostro Paese il monitoraggio pollinico. Su iniziativa dell'Assessorato Ambiente della Regione Emilia Romagna e del CNR, nasce la prima rete regionale pilota di monitoraggio aerobiologico rivolta particolarmente ai granuli pollinici responsabili di allergia. Nel 1980 il campionamento pollinico supera i confini regionali e si estende a tutta la penisola, tanto che due anni dopo operano in Italia 20 stazioni. Attualmente vi sono in Italia 57 centri di monitoraggio aerobiologico che operano nell'ambito dell'Associazione Italiana di Aerobiologia, fondata a Bologna nel marzo 1985 e comprendente studiosi provenienti da discipline diverse. E' indispensabile che ogni punto di monitoraggio pollinico abbia un confronto costante con i risultati clinici e la componente vegetale del territorio. A Ferrara i risultati di cinque anni di rilevamento hanno evidenziato tre gruppi principali di pollini allergenici: Graminacee, Urticaee (in particolare il genere Parietaria), Composite (in particolare il genere Artemisia), mentre scarsa è l'incidenza dei pollini degli alberi. Ricerche cliniche, svolte nel 1980 e nel 1982 su due gruppi di pazienti allergopatici, confermano i dati aerobiologici. Le percentuali di positività agli skin-tests sono per le Graminacee il 90% (1980) e l'88% (1982), ler le Urticacee il 30% (1980) e il 27% (1982), per le Composite il 15% (1980) e il 12% (1982). Abbiamo effettuato anche un'indagine sul territorio della provincia di Ferrara per verificare la presenza e consistenza di alcune specie di piante allergeniche. Tralasciando le Graminacee che, per essere assai diffuse, non giustificano una verifica sul campo, abbiamo dato maggior spazio ai generi Parietaria e Urtica (fam. Urticacee) e ai generi Artemisia e Ambrosia (fam. Composite). Nel nostro territorio sono presenti solamente 2 specie diParietaria (P. officinalis eP. diffusa) e 2 specie diUrtica (U. diodica eU. urens). Riguardo alle Composite abbiamo verificato la presenza di 4 specie diArtemisia molto comuni in tutto il territorio ferrarese, mentre 2 specie diAmbrosia sono diffuse soltanto lungo il litorale. Si può affermare che, in campo allergologico, la combinazione di dati aerobiologici, clinici e botanici costituisce la base per giungere ad una diagnosi corretta e per impostare una terapia il più mirata possibile.      

Effetto della rimozione dei fiori sulla crescita delle piante e sul contenuto in leghemoglobina dei tubercoli radicali di pisello e fava

Abstract

Observations on vegetative growth and leghemoglobin contents of root nodules of pea and bean plants after flower bud removal. — These studies found their origin in the papers by MATTIROLO (1899) on the effect of the removal of flowers as they formed in bean plants; he observed that deflowering resulted in extraordinary plant growth, stem branching and flower buds formation as well as in a delayed root nodule senescence. In the light of modern knowledge of the leghemoglobin role in symbiotic nitrogen fixation, the aim of the present research was to ascertain any possible relation between flower bud removal and haeme pigment contents in the root nodules. The experiments were carried out during two growing seasons (1966 and 1970) using Vicia faba L. cv. Regina and Pisum sativum L. cv. Senatore during 1966 and cv. Vittoria in 1970. In both control and test plants the seasonal trends of average plant height, fresh and dry weight of vegetative portions, fresh and dry weight of root system, fresh weight of nodules, root nodule leghemoglobin concentration and total leghemoglobin content per plant, were determined. The data obtained are quoted in Table 2 and reported in Figures 1, 2, and 3. The removal of flower buds caused in both species: an increased plant growth, a marked stem branching, a longer blooming period, an increased flower number, an increased root nodule number and a certain delay in root nodule reabsorption. Deflowering did not significantly extend — at least in the species studied — life span (senescence was delayed only of one week). On the basis of these and of other Authors' results, we conclude that deflowering may actually delay senescence; the size of this delay, however, depends on the plant species considered and is fairly negligible both in pea and bean. The different effects of deflowering and of preventing floral induction on life span extension, are discussed, and these facts lead to consider floral induction as the onset of a chain of processes leading annual plants toward senescence in a more or less delayable, but definitive way. After having stressed the generally accepted importance of leghemoglobin concentration as an index of nodule nitrogen fixing ability, a correlation between biomass increase of test plants and number and total weight increase of root nodules, is put in evidence. No correlation between test plant biomass and the leghemoglobin concentration in root nodules, was however observed. Leghemoglobin concentration in root nodules is known to change in connection with various factors depending either on host plants and on Rhizobium strains and also in connection with several environmental conditions. Any prevented flower onset (ROPONEN and VIRTANEN, 1968) and deflowering (our data) however exerted no significant influence. The effects of flower bud removal were therefore the following: increased stem, leaf and root weights and increased root nodule number; no difference between control and test plants was however observed as regards size and leghemoglobin concentration of root nodules and hence probably no difference as regards their nitrogen fixing ability.     

Osservazioni sul ciclo di sviluppo delle gemme di esemplari mascbili e femminili di Ginkyo biloba L.

Abstract

Observations on the development cycle of the buds of male and female specimens of Ginkyo biloba L. – A study of the buds of long shood and short shoot of male and female Ginkyo biloba L. individuals reveals the following: 1) All the buds of the male individuals are bigger and round in shape while those of the female individuals are smaller and conical. 2) Among individuals of the same sex there are no differences between the buds of long and short shoots except that the latter are always bigger. 3) All the buds, both male and female, show a constant number of buds scales (7–14), embryonic leaves (3–7) and leaf primordia (3–4). 4) The increase in diameters is greater in the male than in the female buds. 5) When opening, the buds of the male short shoots can get as big as 11,5 mm × 11,5 mm and those of the female short shoots 5 mmx4 mm. At this time, the long shoots of both sexes show a less marked differences in size (♂ 5 mm × 5 mm; 9 4 mm × 3,5 mm). 6) The male buds of both long and short shoots are always mixed, that is they are provided with a very small apex and pollen sacs. Only on exceptional cases has sterility been observed. On the other hand female buds are mixed, that is they are provided with a shoot apex and ovules, only in the long shoots of three or more years of age and not always; while the buds of the long shoots are always sterile. 7) Opening of the buds, which in both sexes occurs from the base upwards, takes place at the middle of March in the male and in the first decade of April in the female individuals. 8) The appearence of sex, starting from the base, takes place at an earlier time in male individuals. In fact in the buds of the male short shoots it appears as early as July. In the buds of the female short shoots it appears in October. 9) Pollen cones do not appear at the same time in all the buds of the two types of shoot. They are found in the buds of the short shoots in July, in October in the lateral buds of the long shoots and in November in the terminal buds of the same type of shoots. 10) Ovules appear only in some buds of short shoots three or more year old. They are never present in the long and short shoots one or two year old buds. 11) The dates of appearance of the pollen cones and ovules in our Florentine specimens are exactly the same as those reported by SPRECHER (1907) for the Ginkyo plants growing in Geneva.     

Sull'uso delle forme biologiche nella classificazione fitosociologica e nella verifica sintassonomica di alcuni aspetti degli xerobrometi appenninici

Abstract

The use of life-forms in phytosociological classifications: an example with data from xerophilous pastures.—The classification power of life-forms connecting to phytosociological data processing for xerophilous pastures of Central Southern Apennine (ecological classification) is discussed. Saturejo montanae-Brometum erecti Avena, Blasi 1979 and Seslerio nitidae-Brometum Bruno 1968 are compared on the basis of their weighted life-forms spectra. The high correlation between classification obtained by floristic data and classifications by life-forms is stressed.     

Ricerche sul meristema apicale della radice II. II contenuto di coenzimi riboflavinici

Abstract

RESEARCHES ON ROOT APEX MERISTEM. II. RIBOFLAVINE COENZYMES. — FMN and FAD contents have been measured (by the method of BURCH et al.) in the roots of etiolated pea seedlings. It has been found that FMN and FAD content is higher, when referred to fresh weight, in the 2 mm. apical segment than in the next 2–4 mm segment.

On a protein basis, FMN is more abundant in the 2–4 mm segment than in the 0–2 mm apical segment.

The opposite is true for FAD (see table). The apical (meristematic) segment is therefore characterized by a higher FAD/FMN ratio (its value is 1) than the next 2–4 mm segment, where the ratio FAD/FMN is 0.29.