Frammenti cotiledonari di Aesculus hippocastanum L. coltivati in vitro. Primi dati sul comportamento dell'amido e dell'escina

Abstract

Fragments of Aesculus hippocastanum L. cotyledons grown in vitro. First results about starch and aescin characteristic features.—Cotyledon fragments of Aesculus hippocastanum grown in vitro in different media have been able to form callus and roots. The starch granules in the new cells are compound in structure and morphologically different from the simple cotyledon granules, whereas they are similar to the granules of the other parts of the plant in toto. Moreover, the callus has no aescin even though it originates from the cotyledor tissues.     

Cultura in Vitro di Ovuli di Pinus Pinea L.

Abstract

Pinus Pinea ovules cultured in vitro. — The degree of growth and autonomical differentiation of Pinus pinea L. proembryo has been studied by means of controlled cultures in vitro of excised ovules.

Proembryos in vitro undergo involution and initials of their growth points change back into parenchimatoides cells.

Completely differentiated embryos cultivated in vitro behave as if they were not physiologicaly ripe in all their parts. Embryos cultured in august, september and october develop into rocotless seedlings. Only embryos cultured in november have roots able to elongate where germinating, but in a still scarce degree in comparison with hypocotile and cotiledons. Hypocotil root ratio is inverted as regards what happens in nature.

The primary endosperm of Pinus pinea L. cultivated in vitro undergoes surface diffuse proliferation.

A case of polyembriony has been observed.     

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.     

In situ Imaging of Pea Starch in Seeds

A method has been developed for the in situ imaging of starch in dry seeds by exploiting the tight packing of the starch and protein storage reserves within the cells of the embryo. The method can be adapted to prepare seed samples which are suitable for light microscopy (birefringence and iodine staining), scanning electron microscopy and atomic force microscopy. Its potential for imaging the internal structure of starch granules without any prior isolation process is demonstrated for round smooth peas. Using a standard ultramicrotome, thin sections were cut directly from selected regions of dry pea seeds and examined by light microscopy before and after hydration. The sectioning procedure left a planed surface with the internal structure of the starch granules exposed. This material was examined by scanning electron microscopy and atomic force microscopy directly or after controlled hydration. In the hydrated pea samples, the growth ring structure and blocklet sub-structure of individual starch granules within the seed were visualised directly by atomic force microscopy. Furthermore, the effects of hydration and staining were monitored and have been used to introduce contrast into the images. The observations have revealed new information on the blocklet distribution within pea starch granules and the physical origins of the growth ring structure of the granules: the blocklet distribution suggests that the granules contain alternating bands with different levels of crystallinity, rather than alternating amorphous and crystalline growth rings.     

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.     

La vegetazione degli stagni della zona di Olbia (Sardegna nord-orientale)

Abstract

Vegetation of the ponds in the zone of Olbia (northeast Sardinia). – The present paper contains a study on the vegetation of the ponds and marshes in the neighbourhood of Olbia. The following well determined associations have been ascertained: Chaetomorpho-Ruppietum, Salicornietum fruticosae, Arthrocnemeto-Limoniastretum monopetali, Juncetum maritimi, Scirpetum maritimi, Caricetum divisae, Schoeneto-Plantaginetum crassifoliae. Furthermore, some other consociations have been observed (with: Pholiurus incurvas and Triglochin bulbosum; Juncus subulatus; Scirpus setaceus and Spergularia rubra; Agropyrum elongatum and Spartina juncea).

The authors have also taken into consideration the present distribution of the vegetation in relation to the modifications due to the fact that this area has been reclaimed.     

Residui di Leccete pure e miste sulla Murgia di Putignano

Summary

Purpose of this paper is to point out the residues of Quercus Ilex woods in the hilly region of Murgia di Putignano (Puglia) which lies inside the distribution area of Q. trojana, now the main wood-forming tree-species of this territory.

Fourteen different small Q. Ilex stands are mentioned, as marked on alleged map. One of them (n° 1 on the map) has been more carefully studied through a whole year, and all plants growing in it have been collected.     

Osser Vazioni Anatomiche su Foglie di Olivo Sane ed Attaccate da Spilocaea Oleagina (Cast.) Hugh.

Abstract

Anatomical observations on sound leaves and by SPILOCAEA OLEAGINA (Cast.) Hug infected leaves in Olive-tree. — The author has studied the anatomical characters comparatively between two cv. of Olive tree growing in Messina district (Sicily): cv. Ogliarola, receptive to Spilocaea oleagina (Cast.) Hug, and cv. Leccino not receptive.

Anatomical differences of the leaf as a whole and particularly of the «cuticular membrane » have been observed between sound leaves and attacked leaves of cv. Ogliarola, and sound leaves of cv. Leccino.

The main conclusions drawn from this study are the following ones:

The mesophyll is thicker in cv. Ogliarola and thinner in cv. Leccino.

The cuticular membrane and its 4 layers are thicker in Ogliarola leaves than in Leccino's ones.

Ogliarola leaves attacked by the fungus show a cuticolar membrane thicker than the sound leaves of the same cultivar.

Hiperplastic and hipertrophic tissues have been observed in Ogliarola leaves attacked by Spilocaea, expecially epidermis and palisade.

The anatomical causes of resistence and receptivity are prospected.     

Ulteriori Osservazioni Sulla Variabilità Del Legno Secondario in Prunus Persica Stokes

Abstract

Further observations on the variability of the secondary wood of PRUNUS PERSICA Stokes. — The length of both fibres and vessel members and the age of cambium in the trunk of a wild specimen of Prunus persica are positively correlated; no relation exists between the length of the above mentioned elements and the width of growth layers.

The relation between the intrasive growth of fibres and either age of cambium or width of growth layers has been also calculated but no significant relation has been attained.

The results have been compared with those obtained in the previous study of a trunk of a grafted Prunus persica, which are very different and quite peculiar mainly as to a decrease in length of fibres and vessel members with aging of cambium. The growing practice to which the tree may have been subjected is regarded as the possible cause of this peculiarity.     

Microtuboli in Cellule Parenchimatiche ed Epidermiche di Coleottile di Avena

Abstract

Microtubules in parenchyma and epidermis cells of avena coleoptile. — The fine structure of differentiating parenchyma and epidermis cells of the oat coleoptile, fixed in glutaraldehyde-osmium tetroxide, or glutaraldehyde-potassium permanganate, was investigated. Tubular structures have been observed aligned in the peripheral cytoplasm, between the cell wall and the plasma membrane, embedded in the cell wall and inside the tonoplast in the vacuoles.

The nature and function of these structures are yet unknown. Microtubular structures, localized beneath and above the plasma membrane, have been associated to the wall development; the function of the microtubules observed in vacuoles results, anyhow, of far problematic interpretation.     

Monte Linas nuovo anello di congiunzione nell'areale della Scilla obtusifolia Poir

Abstract

MONTE LINAS, A NEW BRIGDE STATION IN THE SARDINIAN DISTRIBUTION OF SCILLA OBTUSIFOLIA POIR. — Two new phytocenosis of Scilla obtusifolia Poir. in Sardinia on Monte Linas have been described; their particular interest is that they connect the so far stations of this species in Sardinia. Monte Linas acts as a bridge between the southern sardinian stations and the northern ones, which have been already described by DESOLE (1959).     

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.     

L'osmo-Resistenza di Dunaliella Salina Ricerche Ultrastrutturali

Abstract

The resistance of DUNALIELLA SALINA TO OSMOTIC STRESSES. ULTRASTRUCTURAL RESEARCHES. — The mechanisms which confer to Dunaliella salina its high resistance to osmotic stresses have been studied from a cytological point of view. For this purpose the Authors have examined the ultrastructural changes following a great rise or fall in the osmolarity of the normal culture medium.

When the tonicity of the nutrient medium is suddenly lowered the response of the alga is given by an instantaneous and general swelling. The whole cell and the single cytoplasmic structures appear equally swollen and the state of dispersion of the stroma of cellular organelles is highly increased. This shows clearly that a conspicuous amount of water has penetrated in every part of cell and suggests that the plasmatic cell membrane and the inner cytoplasmic boundaries may be considered as semipermeable membranes. The response of the different cellular organelles to a hypertonic shock is not quite identical; the mitochondria show for example a quite uniform type of swelling which does not alter deeply their morphological aspect, whilst in the inner space of the nuclear envelope wide sacks appear suggesting that the outer layer of the double membrane of the nucleus may be more permeable to water than the inner one. In the chloroplasts the flattened sacks formed by paired lamellae having blind endings in the peristromium swell up giving rise to conspicuous vesicles. This proves that the permeability to water of the lamellae is greater than that of the external plastidial boundary.

A sudden and strong hypertonic stress causes a great loss of water from every part of the cell. The alga appears indeed shrunken and shrinking phenomena can be see in all cytoplasmic organelles together with a greater electron density of their stroma. The two layers of the nuclear membrane and the lamellar pairs forming the sacculi in the chloroplasts stick closely together causing a nearly total disappearance of the inner space. This shows that the formation of large vesicles after a sudden hypotonic shock is really due to a different permeability of the two layers of the membrane and not to localised osmotic gradients.

In both cases the quite conspicuous structural variations appear reversible and the alga returns to the normal aspect in a comparatively short time.

From these observations it is concluded that the resistance of Dunaliella salina to severe osmotic shocks (which in our experimental conditions were probably more sudded than in the natural environment of the cells) is not due to a mechanism isolating the cells from the external medium or maïntaining homeostatic conditions but rather to a ready permeability of the plasmatic membranes to water and ions. As a consequence an equilibrium between internal and external osmotic conditions is established within the cell in a sufficiently short time allowing normal life conditions.

It has to be observed that during the short time span necessary for the restablishment of a new osmotic equilibrium and of a normal aspect of the plasmatic structures the cells show some clear symptome of suffering consisting in a loss of the motility and in an altered metabolism. Although this time is rather short, it appears clear that the hardness of Dunaliella to osmotic shocks involves a specific resistance of plasma proteins to denaturation.     

Effect of granule size on the interference colors of starch in polarized light

Abstract

A Nikitin-Berek compensator tilted at 5.5° in a polarizing microscope was used to create a background second-order blue interference color against which starch granules were examined. A grating monochromator showed the first interference minimum of the background was at 590 nm. Starch granules have a radial molecular structure. Thus, some radii were in line with the axis of the compensator while others were across the compensator axis. Where radial birefringence counteracted the background birefringence, starch granules had two quadrants with a bright yellow first-order interference color. Where radial birefringence added to the background birefringence, there were two quadrants of second-order blue (higher than the background). In yellow quadrants where birefringence was reduced, the wavelength of the first interference minimum was reduced. In blue quadrants where birefringence was increased, the wavelength of the first interference minimum was increased. The extent to which the interference minimum of the background birefringence was shifted by starch granules was strongly dependent on the size of the starch granules. For yellow quadrants, the shifts were: r = ?0.87, P < 0.001, n = 22 for corn starch; r = ? 0.94, P <0.001, n = 22 for tapioca starch; and r = ?0.94, P <0.001, n = 12 for potato starch. For blue quadrants, the shifts were: r = 0.80, P < 0.001, n = 22 for corn; r = 0.81, P < 0.001, n = 22 for tapioca; and r = 0.93, P < 0.001, n = 16 for potato. When interference colors are used to evaluate starch granules, the granules should be similar in size or a correction must be made for granule size, and the Michel-Lévy chart of interference colors may be used to collect data subjectively.     

Reazioni delle piante di Ricinus communis a incisioni sperimentali

Summary

The author has produced wounds in the stem of Ricinus communis, studing the regeneration and cicatrization processes.

The rapidity of the surface cicatrization is in relation with the water loss of the waunded cells.

Both in the stems woumded let free and in those in which an extra tissue has been introduced, the cicatrization processes tacke place. They only take place with different velocity. The healing process lead to the reconstruction of the cortical and the conducting tissues.

The whole reconstruction of the stele may occur, when the flow of the assimilated stuffs is slowed. Sothat it is probable that the regeneration depends more upon the tissue nutrition tham on a specifical properti of the tissues.     

Cytochemical study of developing anthers of Amomum villosum Lour.

We analyzed anther development in Amomum villosum Lour. (Zingiberaceae) using the periodic acid-Schiff's technique and Sudan black staining to test for the presence of starch and lipids, respectively. Our analyses showed that microspore mother cells of A. villosum lack typical callose walls, and numerous lipid granules appear in the cells early in development. Some starch granules are present in anther wall cells, but not in tapetal cells. After meiosis, numerous lipid granules remain unchanged in the microspores. During microspore development, some small starch granules first appear in the central cell region, and then the starch granules increase in size. After microspore division, the bicellular pollen grains become filled with starch and lipids, and remain in this state until the pollen grains reach maturity. At anthesis, the anther wall of A. villosum consists of several layers of endothecium cells with an evidently thickened radial wall, and some layers of parenchyma cells containing numerous starch granules.     

Azione di Nucleosidi e Relative Basi su Alcuni Aspetti Fisiologici di Rhizobium Leguminosarum Frank

Abstract

On the action of some nucleosides and related bases on some physiologiacal aspects of RHIZOBIUM LEGUMINOSARUM Frank. — Research was carried out on the action of some nucleosides and related bases on some physiological aspects of Rhizobium leguminosarum Frank. The compounds tested were: adenine, adenosine, cytosine, guanine, guanosine, hypoxantine, inosine, thymine, thymidine, uracil, uridine.

Pyrimidinic nucleosides, apart from the disappearance of ribose, behave similarly to their bases.

The bases and nucleosides tested stimulate changes in the respiration of R. leguminosarum. Remarkably different values are observed in the endogenous respiration when compared to the control, and a remarkable delay in the beginning of respiration in the case of cells precultivated in presence of cytidine, uridine and thymidine. A number of these cells were later found to have an anaerobic metabolism, at least in the starting period. These findings may be explained admitting that the regulatory system of Rhizobium, with regard to oxygen uptake, are dependent on the presence of certain compunds, including some nucleosides, which the microorganism is in contact with within the nodule.

Apart from cytidine sulphate, there is a fundamental stimulatory effect on the growth of R. leguminosarum. After 24 hours incubation, purinic bases and their nucleosides are not detectable in cultural media. Thymine and cytosine, however, are still present in the medium, or have been transforned into uracil; the latter undergoes no transformation in the medium     

Osservazioni Anatomiche Su Alyssum Leucadeum Guss

Summary

Alyssum leucadeum Guss. is an endemic Apulian chamephyte, growing on rocks; material collected at Santa Maria di Leuca has been studied anatomically and the following observations have been made.

In the basal thick woody stem the sclerenchimatic tissue is well developed, and is divided up, by parenchima, in many bands which are normally disposed in regular concentric rings while in some cases a single band can be separated by the parenchimatic tissue into «islands» forming tangential rows.

A few tubes are to be found in the sclerenchimatic bands but in very small number compared with the tubes observed in the parenchima. At times a sclerenchimatic band can be connected to the next one towards the outside through radial sclerenchimatic strands, making the stem more resistant mechanically.

The parenchimatic bands interposed between the sclerenchimatic ones are composed of parenchima cells rich in starch. Starch consumption proceeds from the inside towards the outside and the outer bands are richer in starch. Inside the parenchima bands are islands of conducting tissue: the tubes being neither numerous nor large, as is to be expected in a xeromorphic plant. The islands of conducting tissue are sometimes surrounded by a sclerenchimatic sheath.

The alternate succession of concentric rings of soft and hard tissue, together with the arrangement of the conducting elements in isolated groups inside the soft tissue, the groups being sometimes surrounded by a mechanical sheath, show that the stem is provided with great plasticity, is able to shape itself according to the space it finds in the rocks, and can undergo deformations, compressions, etc. An even greater plasticity can be obtained if necessary by resolving the sclerenchimatic bands in several smaller islands. Such a structure, apart from the width of tubes lumina, recalls somehow the secondary structure of certain lianas where the succession of soft and hard tissues gives a great plasticity to the stem.

The structure of the root is similar to that of the stem, the parenchimatic bands being thicker in the radial direction and having cells completely packed with starch.

Alyssum leucadeum is therefore a rock plant with a well defined anatomical constitution and particularly adapted to its habitat. It is a xeromorphic plant, with small tubes, rich in sclerenchimatic and reserve stisues, defended against transpiration by a complex covering of hairs, utilising the winter-spring season for its growth, and the summer as its resting period. Such an annual rithm shows the oriental affinities of this species while the presence of endogenous buds and of a thick layer of cork are other characteristics of plants particularly adapted to a rocky habitat.     

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.     

Embriogenesi nucellare in ovuli non sviluppati di alcune cultivar di arancio del gruppo navel

Abstract

Nucellar embryogenesis in undeveloped ovules in some navel orange cultivars. - Nucellar embryogenesis has been studied in some cultivars of navel orange, Citrus sinensis (L.) Osbeck. Histological observations have been carried out in undeveloped ovules excised 2, 4, 6, 8 months after anthesis. Ovules under study derived a) from flowers naturally pollinated or hand-pollinated with pollen of Poncirus trifoliata (L.) Raf.; b) from emasculated flowers, and c) from flowers deprived of stigma. In absence of pollination, as well as in absence of fertilization, the nucellar embryos reached the globular stage.