Ricerche Sull'infrastruttura del Coleottile di Avena

Abstract

Researches on ultrastructure of Avena coleoptile. 3. The sieve elements. — A study on the ultrastructural organization of the mature sieve elements of Avena coleoptile has been carried out. Data suggest that functional phloem tubes are alive and remain alive until they are working. Judging on morphological basis, the metabolic activity of sieve elements should be of peculiar type and low in comparison to that of the companion cells. In fact the cytoplasm is located in a narrow parietal strand, mitochondria, Golgi apparatus and endoplasmic reticulum are present, but they appear very modified; plastids and nucleus are absent. The cytoplasm is bounded externally by a normal plasmalemma, whilst the vacuole has no visible limits: a tonoplast is, therefore not identifiable.

The strands connecting the superimposed sieve elements with one another through the sieve plate result to be made by a double membrane system very similar to the endoplasmic reticulum, which we believe to realize cytoplasmic continuity between phloem tubes.

The data reported are more favorable to the existence in the sieve tubes of an active mechanism of translocation of organic solutes than a passive mass-flow.

The collaboration of companion cells in the translocation mechanism has been discussed.     

Ricerche Sulla Cultura Sommersa di Cellule Singole di Piante Superiori

Abstract

Research on submerged culture of single cells of higher plants. — The author describes a method which allows to obtain submerged cultures of single cells of Phaseolus vulgaris and Nicotiana tabacum. The medium composition in macroelements in the culture on agar appears to effect to a great extent the ability of tissues to dissociate into single cells in the subsequent liquid culture. In this respect Heller's solution results to be more suitable than Gautheret's and Hildebrandt and Ri-ker's.

Cells are grown at 24 [ddot]C in 300 ml flasks containing 60 ml of broth on a rotary shaker at 220 rpm.

To prevent contaminations some antibacterial agents were added to cultures of Phaseolus vulgaris. Among these Penicillin and Neomycin were not tossic at 20 and 5 ppm concentrations respectively.

The presence of septa, which are observed also in largely vacuolate cells, seems to confirm the ability of single cells to divide.

The optimum 2,4-D concentration for growth decreases from 6 × 10^-8 to 6 × 10^-8 during successive liquid cultures, each of them being inoculated with on amount of the previous one. This fact, showing the adaptation of liquid cultures to decreasing concentrations of the growth hormone, is in agreement with previous observations in solid cultures by several authors.     

Divisione Eterotipica in Cellule Somatiche di Sambucus Ebulus L.

Summary

The Author has studied the evolution of the somatic cells constituting the basal portion of the style-tissue in Sambucus Ebulus L. Simulating a sporogenous tissue, these cells undergo an usual heterotypic division with formation of bivalents and binucleate cells (two haploid nuclei). No cell-wall formation was observed in any case. During the degeneration of this sporogenous-like tissue, occuring soon after the anthesis, a fusion of nuclei in some cells was observed.     

Osservazioni Sulle Infrastrutture di Anabaena Cycadinae E delle Cellule dei Tubercoli Radicali di Cycas Revoluta

Abstract

Observations on the infrastructures of ANABAENA CYCADINAE and of root-nodules cells of CYCAS REVOLUTA. — Light and electron microscope observations carried on the fine and ultrafine sections of root-nodules of Cycas revoluta, brought in evidence differences structural and infrastructural of cells. These differences concern mainly the modifications presented by reticulum endoplasmic which in middle-aged cells takes a fragmentary and vescicular aspect, and the mitochondria which, in the same cells, show short cristae starting by outside wall of the organul.

About the plastyds, I could bring in evidence that there is plenty of leucoplasts but the proplastyds are still numerous, as the cloroplastyds showing some development of the lamellar system and of grana. Plastyds green are present either in while nodules, either in the root-tops.

In no nodules it has been possible to point out the presence of bacteria while it has been possible to verify that Algae have some polymorphism of structure because the chromatoplasma may result essentially of tree different aspects, by me, indicated as reticular type (fig. 12), lamellar type (fig. 10) and type at mixed structure (fig. 11).     

Una Struttura Comparabile Con I Lomasomi Nelle Cellule Austoriali di Cuscuta Pentagona Engelm

Abstract

A structure comparable with the lomasomes in baustorial cells of « Cuscuta pentagona » Engelm. — Electron microscopic observations of haustorial cells in « Cuscuta pentagona » revealed to the A. the presence of some vesicular structures, outside the plasma membrane, comparable to the lomasomes of Moore and McAlear. The vesicles usually group in a bag of the plasma membrane and show an envelope consisting of unit membrane; their shape and size are variable and some of them are not well distinct while some others show ribosome-like bodies inside .In the examined cells the plasma membrane shows prominences which are in connection with the vesicle membrane, so that the A. thinks it possible the derivation of the vesicles from the peripherical cytoplasm. The function of these structures is not yet explained; they are only found in non photosyntetic cells, such as some Mycophyta, dark grown « Avena » coleoptiles and dodder's haustorial cells. The previously ultrastructural researchs on dodder have not pointed out lomasomes, which seem to be exclusive of the haustoria, so that it is possible to suppose a connection between the lomasome function and that of the haustoria.     

Osservazioni Sull'ultrastruttura Delle Cellule Tumorali di un Ibrido Interspecifico del Genere Nicotiana

Abstract

Ultrastructural study of tumor cells of an interspecific hybrid of the genus <Nicotiana>. — The ultrastructure of tumor cells of interspecific hybrids of Nicotiana paniculata × N. langsdorffii, has been investigated. A comparative analysis between meristematic and parenchymatic cells obtained from the tumors plants of the hybrid and the controll tissues indicates that the tumor cells have an altered structure of the nuclei and of the chloroplasts and a very poor cytoplasmic content. These modifications resemble those observed in cells from plants soffering of various metabolic disturbances. A study of structural modification occurring in the necrotic areas shows that the cells undergo aspecific alterations of organelles double mambranes followed by disruption of their structure and eventually condensation of the cytoplasmic matrix.     

Ricerche morfologiche ed istochimiche sulla glia del nevrasse di vertebrati

Riassunto Con metodi istochimici e con metodi di colorazione e di impregnazione per il tessuto gliale fu studiato il materiale intercellulare interposto ai neuroni e fibre nervose nel nevrasse di anfibi urodeli ed anuri (Triton taeniatus, Triton cristatus, Amblystoma mexicanum, Xenopus laevis, Bufo vulgaris, Rana esculenta).I metodi istochimici hanno dimostrato nel materiale interneuronico la esistenza di sostanze del gruppo dei mucopolisaccaridi: esse formano, probabilmente un materiale anisto che dopo fissazione precipita in un reticolo granulare e filamentoso, metacromatico, HOTCHKISS positivo, sensibile all'azione degli enzimi ialuronidasici. Gli studi sui gliociti hanno dimostrato che soltanto nei centri assili degli anfibi anuri esiste una architettura gliovascolare formata prevalentemente da gliociti ependimali: negli altri centri degli anuri e in tutto il nevrasse degli urodeli si trova una rada ed incompleta trama di prolungamenti ependimali con pochi gliociti protoplasmatici siti nella ccmpagine dei centri e sottopiali: le fibre ependimali hanno in questo caso scarsissimi rapporti con i vasi sieche non si può parlare di una vera architettura gliovascolare.Fu dimostrato un sensibile antagonismo fra la intensità delle reazioni istochimiche per la sostanza anista e la complessità delle architétture gliali.Gli autori ritengono esatto definire tutto il materiale interneuronico con il termine di glia proposto dal VIRCHOW: la glia risulta quindi composta da un materiale anisto mucopolisaccaride e dai gliociti riuniti o no in architetture gliovascolari.Dedicate al Prof. F. Baltzer nel suo 70° compleanno.Richerche condotte con il sussidio di fondi del C.N.R.     

Reazioni di natura auxinica ed effetti rizogeni in Allium Cepa L.

Abstract

The biotic vectors for pollen and seed dispersal are compared in respect to their task. The type of rewards as well as the attracting mechanisms for pollinators and animals responsible for seed dispersal are listed. The rise of deception mechanisms (false advertisements) from seduction mechanisms are described.     

Struttura ed ultrastruttura dell'apparato genitale maschile di Drosophila melanogaster Meig.

Summary The structure of the testes of Drosophila melanogaster Meig. was re-examined by means of phase contrast and polarized light microscopy; the ultrastructure was investigated by electron microscopy. Testes from adult virgins of wild strain Varese were studied, but some observations were made also on the testes of different aged insects, of some insects examined at different times during and after mating, and on testes from sterile mutant strains.The results are summarized in the following points: 1) The testis is made up of an external wall and of an internal germinal tissue. The wall appears to be composed of two overlapping layers of very flattened cells: pigmented cells and muscle cells. 2) The ultrastructure of the muscle cells gives rise to some interesting considerations arising out of the fact that there are two kinds of filaments, but without any evident transverse band organization. 3) The testis falls into three different portions according to the organisation of the germinal tissue: the apical portion (spermatogonial zone), the middle portion (spermagenetic zone) and the terminal portion (spermatic zone). 4) The germinal tissue is made up of germinal cells and interstitial cells. The germinal cells occur in groups consisting of a fixed number of elements in a syncytial state: these groups are enveloped by interstitial cells forming the cyst. The cysts can be considered as the supracellular unit of germinal tissue.The results are discussed in relation to numerous problems, such as: the existence and meaning of the syncytial state of the germinal cells; the existence of a functional cycle of the interstitial cells associated with the maturation of germinal elements; the phagocytic and mechanical functions of terminal epithelium; the existence of various movements of germinal tissue elements along the length of the testis from the apical zone to the terminal one.The paper ends with a discussion on functional aspects of the male reproductive organs.

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Ricerche eseguite col sussidio del C.N.R. (Roma).     

Variazioni stagionali di nutrienti minerali ed elementi in traccia nelle foglie di Fagus sylvatica L. a Vallombrosa (FI)

Abstract

Seasonal variations of mineral nutrients and trace elements in Fagus sylvatica L. leaves at Vallombrosa (FI). - During the vegetative periodo 1987 monthly samples of beech leaves were collected in Vallombrosa forest area to determine the nutritive situation of beech trees by leaves analysis. Among nutrients, potassium appears the worst supplied one. Even copper is present in very low values, under the critical level. Heavy metals as manganese, aluminium, lead, cadmium and also iron show a clear increase during the vegetative season.     

Modificazioni Anatomiche ed Istologiche in Apici Radicali di Plantule di Pinus Pinea L. Germinate in Vitro al Buio da Semi Immaturi

Abstract

Histological and anatomical modifications in the root apex of PINUS PINEA L. seedlings grown in vitro from immature seeds, in the dark. — The seeds of Pinus pinea L. take three years to develop reaching maturity during the spring of the forth year. Immature seeds were collected at successive stages and cultivated in vitro in Heller's medium. The seedlings showed atrophy of the root togheter with histological and anatomical modifications of the root apex and formation of a small tuber. The extent of these modifications depends on the age of the seed and on how long the seedling is cultivated in vitro.

Seedlings derived from seeds planted on August 31st and kept in vitro for about a month had an atrophic root through lack of meristematic capacity; in it the secretory and conducting apparatuses had developed but with mixed radical and hypocotilar characters.

Seedlings from unripe seeds planted on September 30th and kept in culture for about one month showed an atrophic root owing to a rapid process of differentiation accompanied by the formation of isolated tracheid-like elements and of discontinuos vascular strands very near to the apex. Lateral proliferations gave rise to masses of various size of unorganised parenchyma which could separate the cortical and cap parenchyma from the central cylinder. In some cases the root cortex, clearly recognisable owing to an advanced process of differentiation, cut off from the central cylinder the root cap cells which degenerated.

Seedlings obtained from seeds planted on October 11th and kept in culture for about one month showed a radical tubercle deriving from fasciation of the main axis which had ceased growing and had formed various abnormal lateral root primordia.     

Ricerche biochimiche ed istochimiche sull'Attivita' lipasica dell' Epitelio Intestinale di Helix pomatia

Ricerche eseguite e pubblicate con un contributo del C.N.R.     

Rapporti Fra Endosperma ed Embrione Nella Germinazione di Pinus Pinea L.

Abstract

Endosperm embryo interrelationships during germination of PINUS PINEA L. (2nd Note). — Experiments have been performed with unripe fresh seeds paralleled with unripe stored seeds (50 days of storage).

The effect of storage is very similar to the effect of further permanence on the tree.

It is confirmed the importance of the endosperm in the germination process already put in evidence in the 1rst note.

The relationships existing between endosperm and embryo during the germination of the seed become more and more strict as the seed ripens, so that in a ripe seed the embryo develops in a normal seedling only in connection of its own endosperm.

In an unripe seed the embryo is uncompletely controlled by its endosperm.

Some remarks have been made about the degree of maturity of the different parts of the embryo.     

Reazioni cito-istologiche ed effetti rizogeni in plantule di alcune Leguminose trattate con 2,4-D

Summary

The author has studied consequences of treatments with 2,4-D on the grown up tissues of seedlings of two species of Leguminose, realizing best effects of mitostimolation, which has permitted a careful research about the caryological costitution of differentiated tissues of Pisum s. and V. Faba.

Having obtained also induction of lateral roots, the author has extended the field of his own researches, for establishing the possibility of growth of lateral roots, induced by hormonical stimolation.