首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Riassunto Nel presente lavoro sono state riportate le concentrazioni polliniche registrate nell' atmosfera di Varese nel 1986. Le principali famiglie di pollini presenti sono state quelle delle Graminacee, Urticacee (Parietaria officinalis) e Betulacee (in particolare Betula alba), seguite da Corilacee, Fagacee, Salicacee e Cupressacee. Scarsa importanza hanno dimostrato, per le basse concentrazioni raggiunte, le Chenipodiacee, le Plantaginacee ed in particolare le Composite. In generale i risultati ottenuti non si sono di molto discostati da quelli riscontrati nel 1985.
Summary This research reports the results of the airborne pollen samplings carried out with a volumetric VPPS 2000 sampler elaborated daily in the area of Varese during year 1986, from March to September. These results were related to some meteorological data (temperature, humidity and rain). The principal pollen's families found are those of Gramineae, Urticaceae (parietaria off.), Betulaceae, Corylaceae, Fagaceae, Salicaceae and Cupressaceae. Chenopodiaceae, Plantaginaceae and Compositae have demonstrated little importance because they reach low concentrations. Generally the results obtained in the year 1986 and in 1985 are similar.
  相似文献   

2.
3.
Riassunto Vengono presentati i risultati del monitoraggio dei pollini allergogeni (18 gruppi botanici + pollini totali) effettuato a Sassari (Sardegna sett.) nel biennio 1984–85, mediante apparecchio campionatore volumetrico ?Burkard?, comparati coi dati dell'indagine clinico-allergologica effettuata contemporaneamente nella zona. La contaminazione pollinica dell' aeroplancton viene messa in relazione con la vegetazione della regione circostante. è stata anche calcolata la conc. oraria dei pollini totali nei vari mesi. Nel 1985 si sono registrati valori di conc. pollinica superiori che nel 1984, specie per i pollini totali, Oleaceae, Cupressaceae e Quercus. Le Compositae hanno sempre presentato una bassa conc. pollinica, e una scarsa incidenza nelle sensibilizzazioni della zona. Le Gramineae vengono al 1° posto come responsabili di pollinosi. Le Oleaceae hanno presentato valori alti di conc. giorn. (eccezionali nel 1985), mentre l'incidenza di pollinosi da olivo nel Sassarese è risultata assai limitata. Il polline di Urticaceae è presente tutto l'anno, ma soprattutto da metà marzo a metà giugno; si è rilevata nei pazienti pollinosici cross-reattività tra Parietaria e Urtica.   相似文献   

4.
Riassunto

Intorno alla esistenza di forme di canapa diverse per caratteri morfofisologici entro la popolazione solitamente coltivata nella prov. di Torino e che dal maggior centro di diffusione e smercio, Carmagnola, porta il nome, l'A. ha dato pi[ugrave] d'una dimostrazione. Proseguendo la strada iniziata or è un quindicennio, questà indagine tratta della germinabilità della canapa nelle sue espressioni di potenza germinativa (% di semi nati), energia germinaliva (rapidità di germinazione) e longevilà (durata della vitalità dei semi) alla stregua di manifestazioni d'ordine genofenotipico. Onde poter affrontare le non facili ricerche è stato necessario analizzate le cause, di natura a così dire ambientale, che in un senso o nell'altro influenzano la germinabilità della canapuccia. Tra esac, l'A. ha indagato le seguenti:

a) lo stadio di maturazione del seme;

b) il sistema di raccolta del seme;

c) il mezzo o ambiente di conservazione del seme quanto a temperatura e umidità relativa dell'aria;

d) il sistema di conservazione del seme.

Ciò fatto, l'A. passa all'analisi del comportamento ereditario della germinabilità partendo da linee puree di canapa a bassa e ad alta potenza germinativa, a bassa e ad alta energia germinativa estratte, or è un decennio, dalla predetta popolazione di Cannabis saliva. Le ricerche hanno dimostrato che nella fecondazione incestuosa della canapa è possibile ottenere linee diverse nella germinabilità; che tanto la potenza quanto l'energia germinativa sono caratteri ereditari; che la fecondazione incrociata annulla il carattere « bassa germinabilità » emerso nell'incesto e dovuto probabilmente a fattori letali onde s'ottengono forme di canapa a germinabilità elevata anche nelle generazioni — in libera fecondazione — successive alla prima; che la potenza e l'energia germinativa sembrano caratteri geneticamente complessi e sono tra loro indipendenti; che la longevità della canapuccia è apparsa indipendente, dal lato creditario, dalla potenza e dalla energia germinativa accertate nel primo anno di vita di essa.  相似文献   

5.
Zusammenfassung In der Schilddrüse der normalen und reifen Meerschweinchen sind keine unabhängigen Zellen vorhanden, die besondere Merkmale im Ver gleich zu anderen parenchymalen Zellen vorstellen. Die bis jetzt geschilderten klaren und protoplasmareichen Zellen sind in der Tat follikuläre Zellen, die in ihrer innigen Struktur modifiziert sind und die in den Schnitten wegen besonderer Verhältnisse zu dem Bindegewebe und den Gefäßen abgesondert erscheinen. Ihre strukturalen Veränderungen stehen überwiegend in engem Zusammenhang mit der Funktion, die sie bei besonderen funktionellen Beschaffenheiten der Drüse erfüllen sollen.  相似文献   

6.
Abstract

Observations on deep seaweeds (15–50 m) at Punta San Pancrazio, Island of Ischia (Bay of Naples). — Algological research in little known and still well preserved zones of the Bay of Naples have been done to improve our knowledge of underwater flora of the Bay itself and of the southern part of the Tyrrhenian sea. SCUBA diving technique allowed us to detect, namely in the deepest investigated areas, a number of species previously unknown for the Bay of Naples. This research deals only with species found during the summertime, living at depths greater than 15 m.  相似文献   

7.
Abstract

In vitro development of carpospores of Petroglossum nicaeense (Duby) Schotter. This paper describes the germination of carpospores of P. nicaeense (Phyllophoraceae) and the development on glass of new tetrasporophytes to the size of 3–4 mm. Different patterns of development are observed: 1) formation of one or two rizoidal filaments which give rise to an adhesive disc; 2) formation of a morula, of limited growth, and of rizoidal filaments which then originate adhesive discs; 3) formation of a morula which originates a single frond, and formation of filaments that do not form adhesive discs. Eventually, the discs give rise to one or more outgrowths that develop into erect fronds. These fronds reach a 4 mm length 3 months after germination.  相似文献   

8.
Summary

Inhibiting effect of antiauxins on some dehydrogenare enzyme systems in the soluble and in the particulate fractions of extracts from plant tissues.

The effect of several antiauxins (trans-cinnamic acid, diphenylacetic acid, 2–4 dichloroanisole, b-phenylpropionic acid, maleic hydrazide) on dehydrogenasic systems in enzymic preparations from higher plant tissues (cauliflower, pea, artichocke) has been investigated. Dehydrogenase activity has been determined, in the soluble (glucose-6-phosphate) as well as in the particulate (malic TPN linked, malic DPN linked, succinic dehydrogenases) fraction of the protoplasma, by the tetrazolium (used «in vacuum») and the Thunberg methods. Mitochondrial preparations have been obtained through repeated precipitations at 20.000 × g., in the cold, in 0,5 M sucrose.

All of the antiauxins tested, at concentrations ranging between 60 and 400 p. p. m., clearly inhibited dehydrogenase activity, both in the soluble as in the mitochondrial systems. Inhibition appeared non competitive, and indipendent from coenzyme concentration; it was more evident at lower pH values, and it increased with pretreatment of the enzyme with the antiauxins, in the absence of substrate.

These results are interpreted as an evidence for the capacity of antiauxins to act directly on fundamental metabolic systems, even in absence of auxin.

The lack of specificity and the characteristics of the inhibiting action of antiauxins on dehydrogenase systems suggest that they could act through the inactivation of some chemical group of general diffusion and importance among the enzymes of the class here investigated; very probably, of -SH groups.  相似文献   

9.
Abstract

CHANGES IN THE ACTIVITY OF CHLOROGENIC ACID OXIDASE AND OTHER ENZYMES INVOLVED IN OXIDATION AND REDUCTION OF TPN IN AGEING POTATO TUBER SLICES. — The activation of respiration, and in particular of the pentose phosphate pathway, during incubation of potato tuber slices could depend on the increase of activity of oxidative enzymes mediating electron transfer from Gl. 6-P to oxygen.

The present report deals with the activity changes, in the first period of incubation, of the following enzymes: Gl. 6-P-dehydrogenase, TPNH-glutathione reductase, gluta-thione-dehydroascorbate reductase, chlorogenic acid oxidase and a TPNH diaphorase utilizing tetrazolium salts as electron acceptors.

The activity of all of these enzymes, with the exception of TPNH diaphorase, was found to bs, at all stages of incubation, in large excess respect that required to account for the estimated contribution of the pentose phosphate pathway to respiration.

Gl. 6-P dehydrogenase, glutathione reductase and chlorogenic oxidase activities markedly incresed during incubation; but their increase appeared to be clearly delayed (of some hours) respect that of oxygen uptake. This seems to indicate that the increase in activity of these anzymes is rather a consequence than a cause of the respiratory activation.

TPNH diaphorase showed a very low activity in the fresh slices, and it increased quite significantly already in the very first period (5 hours) of incubation. This behaviour suggests the possibility that this enzyme could limit TPNH oxidation, and thus the pentose phosphate pathway activity, and that its activation could be correlated with that of oxidative metabolism in the ageing slices. Further investigation of this hypothesis requires the identification of the natural electron acceptor of this enzyme.  相似文献   

10.
Abstract

We numerically analysed 154 relevés of Potentillo chrysocraspedae–Festucetum airoidis in order to review the compositional variability of these grasslands, the main eco-floristic gradients and the representativeness of the lectotype. Apart from 30 small-sized clusters composed of singular or transitional relevés (outliers), three distinctive groups of 77, 19 and 12 communities were finally retained and denominated as typical (TP), closed (CL) and open (OP) facies, as they were significantly different in terms of total species cover. The three facies are well separated but do not form distinctive clusters in the non-metric multidimensional scaling (NMDS) ordination space. Juncus trifidus and Agrostis rupestris are the best differential species of OP and TP, respectively, whereas the best discriminator of CL is the higher cover of F. airoides. There are no significant differences between the three facies regarding altitude. The floristic structure of CL indicates poorer but moister soils compared with the other facies. CL may represent either a post-disturbance, recovery phase following sheep overgrazing and intensive trampling, or a late seral stage. OP gathers communities that are little disturbed and mainly occur on ridges and upper, sunny slopes. Although well distinguished floristically, TP is weakly defined in terms of homotoneity and complexity of the core species assemblage. The most representative relevé of TP is poorer in character species than the relevé lectotype (5 versus 12), the latter being classified as an outlier in terms of normal specific assemblage. Such patterns may reflect the spatio-temporal heterogeneity in alpine grasslands due to uncontrolled, intensive grazing and stochastic natural disturbances.  相似文献   

11.
Abstract

Growth response of coleoptile sections from four Italian cultivars of wheat to some growth regulators.—The following Italian wheat varieties were used to obtain the coleoptile sections used throughout the experiments: Funo, S. Pastore, Abbondanza, Generoso.

The growth substances tested were Indolacetic acid (IAA), Abscisic acid (ABA), Kinetin and Gibberellic acid.

The colcoptile response of each variety was tested with three different concentrations for each growth regulator in combination with two sucrose concentrations and three different pH levels.

The experiments indicated that the coleoptiles from the variety « Funo » react linearly to incresing IAA and ABA concentration resulting the best one to be used in this bioassay.  相似文献   

12.
Abstract

Effects of inhibitors of protein synthesis on the development of metabolic activity in the endosperm during the germination of castor bean seeds. — The effect of chloramphenicol, streptomycin and actinomycin-C on the increase of the activities of glyceroaldehyde-phosphate dehydrogenase, aldolase, glucose-6-phosphate dehydrogenase, fructose 1–6 diphosphate-1-phosphatase, phosphomonoesterase, in the endosperm of germinating castor bean seeds was investigated.

In all cases, the protein synthesis inhibitors depressed the activation of the enzymes tested: in particular, actinomycin (50 μg/ml) completely suppressed the increase of the activities.

The development of the rate of oxygen uptake and the conversion of fats to sugars was strongly affected by the inhibitors.

These data suggest that the increase of the activities of several enzymes in the germinating endosperm is dependent on enzyme synthesis rather than on the conversion from the inactive to the active form of the enzymes.  相似文献   

13.
Abstract

Floristic affinity of bentonic vegetational types of Cala di Mitigliano (Massa Lubrense Napoli). — We have studied the bentonic plants community in the Cala di Mitigliano. It appears that some species compositions repeat themselves with a certain regularity. This fact lets us recognize and consequently classify them. In Cala di Mitigliano we took an interest and considered only such species compositions. We calculated, in them and between them, the coefficient of affinity by SÖRENSEN (1948). The cluster analysis by average linkage and the use of an index of «individualisation» (Feoli, ined.) based on floristic comparison showed that the species compositions, although we chose such ones to describe the vegetation, equally change gradually from place to place.  相似文献   

14.
Abstract

Frequency and localization of mitosis in lateral root primordia of Marsilea strigosa. At different stages of development of the root primordium of Marsilea strigosa the apical cell undergoes a strong decline in mitotic activity whilst active divisions occur in the mass of cells sorrounding the apical. In the present paper data on the frequency and localization of mitosis in lateral root primordia are collected.  相似文献   

15.
Abstract

Comparative researches on morphology and physiology of PICEA and LARIX. Fresh weight and chlorophyll content in seedlings kept at various light intensities. — The fresh weight and the chlorophyll content of lots of seedlings from Larix decidua and Picea excelsa grown on sand for 12 days in climatic cell at 25 [ddot]C with 86% relative humidity and a light intensity of 90, 250, 500, 1.000, 2.000 and 4.000 lux were determined.

The fresh weight of Picea seedlings is not significantly affected by all light intensities except for 4.000 lux, where it is 20% higher. Even in dim light (90 lux) the fresh weight of Picea seedlings is only 7% inferior to that of the lot kept at 2.000 lux.

The results obtained in Larix are remarkably different; its fresh weight is more influenced by the light intensity: at 4.000 lux, e. g., the fresh weight is considerably higher (more than 20%) than the arithmetical mean of all the lots, while at 90 lux it appears greatly inferior (30%) to the lot kept at 2.000 lux.

No correlation exhists between fresh weight and chlorophyll content variations.

In Larix only the difference between seedlings kept at 250 lux and 90 lux is very strong. In the latter the chlorophyll content for g. f. w. is 40% inferior to the average of all the lots. At the maxime intensities the chlorophyll content of Larix seedlings appears to be particularly increased, while that of Picea seedlings is slightly inferior to that observed at 2.000 lux.

These figures are in agreement with the special ecology of the two plants and particularly with the light need of Larix, as it is clearly demonstrated by the fresh weight and chlorophyll content per g. f. w. and by the different ratio in chlorophyll contents of the lots of seedlings kept at 2.000 and 4.000 lux.  相似文献   

16.
Zusammenfassung Durch Anwendung der Explantationsmethode vonMangold wird der Rumpfschwanzteil der Medullarplatte in vitro explantiert, um die Evolutionsfähigkeiten der isolierten Medullaranlage und die Entwicklungskorrelationen zwischen dem Chorda-Mesodermkomplex und der Morphohistogenese des Rückenmarks zu studieren.Es wird vor allem festgestellt, daß der Neuralstrang, der sich aus der explantierten Neuralplatte bildet, auch ohne Mitwirkung der Chorda oder irgendeines Stützorgans verlängerungsfähig ist.Von großer Bedeutung für die Morphohistogenese des Neuralstranges scheint die Chorda zu sein, und gewissermaßen auch das Mesoderm.Fehlt das Mesoderm, so schmelzen die Ganglien zu einer einzigen Masse zusammen, ventral zum Neuralstrang; die Struktur des Neuralstranges erleidet aber dadurch keine Veränderung.Fehlt die Chorda dagegen, so treten sehr wichtige Veränderungen im Neuralstrang ein, d. h. übermäßige große der Neuralröhre oder mehrfache Röhrenbildung, Zerstörung der Zellen- und Fasernanordnung, Neuroblastenabsonderung aus dem Rumpfteil des Neuralstranges.Wenn aber, auch bei fehlender Chorda, der Neuralstrang von Mesodermmassen begleitet wird, ist seine Struktur viel regelmäßiger.Es scheint also, daß das Mesoderm, außer die Wirkung auf die Zerteilung der Ganglienanlagen, auch gewissermaßen die ausgebliebene Wirkung der Chorda ersetzen kann.  相似文献   

17.
Abstract

Dioecy ensures cross pollination but pollen must travel from male to female plants, sometimes covering long distances. The present study concerns the reproductive strategy of two Italian dioecious plants: Mercurialis annua L. and Bryonia dioica L. The former is anemophilous and the latter is entomophilous; the latter has nectar and pollen as rewards. The distribution of pollen grains on the stigma is very different in the two species, reflecting the different types of pollination. In both species there is a number-dependent mechanism of pollen germination on the stigma. This mechanism could enhance male gametophytic competition.  相似文献   

18.
Endophytes are micro-organisms that colonize the internal tissues of plants without inducing signs of negative effects and that can provide benefits to plant health and yield. In the present work, the culturable bacterial endophyte community, colonizing vegetative organs of grapevine, was isolated from surface-sterilized plant tissues and characterized by molecular methods. From roots, shoots and leaves of Vitis viniferaGlera”, located in six different vineyards throughout the Conegliano-Valdobbiadene DOCG area (Veneto, Italy), 381 culturable strains were successfully isolated; amplified ribosomal DNA restriction analysis and nucleotide sequencing showed that approximately 30% of the endophyte community belonged to the genus Bacillus, which was the most represented; other genera such as Staphylococcus, Microbacterium, Paenibacillus, Curtobacterium, Stenotrophomonas, Variovorax, Micrococcus and Agrococcus were identified. Endophyte community composition within each vine was different in respect to other endophyte populations living in grapevine plants coming from different vineyards; moreover, the bacterial composition changed depending on the season of sampling. The above data highlight the great diversity of culturable bacterial species inhabiting Glera grapevines and open the way for a characterization and selection of strains that could potentially be used to improve the vineyard management for plant growth and yield, plant responses to stresses, biocontrol and biofertilization.  相似文献   

19.
Riassunto Le espansioni terminali degli assoni, che crescono in vitro, possono presentare aspetti diversi. La forma più comune é quella, da lungo tempo nota, di ingrossamenti dell'apice del neurite, i quali emettono esili filamenti ameboidi, transitori. Ma, nelle fibre che crescono nell'interfacie tra un mezzo solido e un mezzo liquido, spesso l'espansione risulta di tenui membraneile ialine in continuo movimento, le quali possono avere varia estensione.Le espansioni membraniformi possono venire in breve tempo retratte e sostituite da fini filamenti ameboidi indipendenti e viceversa; tra queste varie strutture esistono forme intermedie.Non risulta però confermata l'opinione di A. HUGHES che i filamenti transitori siano pieghe di una struttura continua.I vari aspetti, che le espansioni possono assumere, sono l'espressione della grande plasticità della sostanza nervosa. L'accrescimento delle fibre nervose a contatto di una superficie solida é verosimilmente condizione indispensabile, ma non sufficiente per la formazione delle espansioni membraniformi; é probabile che la sostanza del neurite si espanda in veli estremamente tenui, soltanto quando é soggetta a fenomeni di imbibizione, associati a diminuzione della tensione superficiale.Membrane ialine possono essere emesse anche all'apice delle collaterali e, in casi più rari, costituirsi transitoriamente persino lungo il decorso del neurite, a spese di tratti più o meno estesi di questo, che si espandono in superficie.Le fibre nervose in accrescimento presentano manifesti fenomeni di pinocitosi. Essi avvengono sia in corrispondenza dell'espansione terminale, sia nelle collaterali, sia infine lungo il decorso del neurite, in zone in cui esso emette esilissimi filamenti transitori, apparentemente privi di espansione terminale.Si ritiene ehe, con l'introduzione di goccioline di liquido, il neurite assuma dall'ambiente materiali disciolti, i quali, insieme alle sostanze che vengono elaborate dal pirenoforo e che fluiscono nel neurite stesso, verranno utilizzati per l'accrescimento della fibra nervosa.Vien prospettata l'ipotesi che il significato dei fini ramuscoli collaterali, transitori, che il neurite in accrescimento emette di continuo lungo tutta la sua lunghezza, sia essenzialmente trofico.Ricerche eseguite con un contributo del Consiglio Nazionale delle Ricerche.  相似文献   

20.
Abstract

C14O2 fixation in plant tissues « in vitro ». — In the present work it has been examinated the autotrophic and heterotrophic CO2 fixation of explants of « Helianthus tuberosus » « in vitro » and the photosyntetic efficiency of leaves produced from buds of « in vitro » explants of « Cichorium intybus » compared with that of mature leaves from normal plants of the same species. From our results it is evident that « in vitro » explants of « Helianthus tuberosus », grown, in the light, are able to autotrophically incorporate C14O2; the distribution of the radioactivity into the various fractions shows a large influence of the light on the neutral fraction containing sugars (50% of the total radioactivity). In the chlorophyllous explants the dark CO2 fixation is obviously of heterotrophic type: 97% of the total radioactivity is incorporated in amine acids (43%) and the organic acids (53%); on the other hand in the dark grown explants the radioactivity is differently distributed between amino acids (59%) and organic acids (39%). Mature leaves from normal plants and leaves produced from buds of « in vitro » explants of « Cichorium intybus » incorporate the same quantity of C14O2 when expressed per mg of chlorophyll; the different distribution of the radioactivity in the neutral and acid fractions could be explained in terms of a different utilization pathway of the photosynthates in the two tissues.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号