Fernando Fabbri

Electron Microscope Observations on Intranuclear Paracrystals in Some Pteridophyta

SUMMARY77 species of Pteridophyta were investigated at the electron microscope. In mesophyll cells of 59 species an impressive occurrence of intranuclear paracrystals was observed. Their sizes are approximately 1–3 μm varying according to the age of the plant. The paracrystals are usually polygonal-shaped but different forms are frequently encountered. At higher magnification a crystal lattice pattern can be resolved. Its substructure consists of a series of electron-opaque parallel subunits alternated with others whose electron opacity is less evident. The centre to centre spacing between two electron-opaque subunits is about 120 A.A nonspecific proteolytic enzyme (pronase) has been successfully tested, showing the essential proteic nature of the nuclear paracrystals.In general terms a correlation of paracrystals with the aging of the plant is indicated. No inverse size relationship, as reported by other authors, between nucleolus and these paracrystal-line formations was observed.Taxonomic perspectives ...

Dati Cariologici Sull'Arisarum Proboscideum (L.) Savi. II

Abstract Caryological data on «Arisarum proboscideum» (L.) Savi. II. – In specimens of «Arisarum proboscideum» (L.) Savi collected near Acerno (Salerno) two different chromosome numbers – 2n = 28 and 2n = 42 – have been found. In two localities of Tuscany (Consuma, in the upper Valdarno, and San-sepolcro, near Arezzo) only the number 2n = 28 has been found, as it was already reported for Reggello (FABBRI 1966a). Moreover, in regard to the number of female flowers present in each spadix, a greater variability has been observed in the Acerno and Avellino populations (1 – 6 fem. flowers; see FABBRI 1966b) than in the Tuscan ones (1 – 3 fem. flowers); this difference in variability could be possibly connected with the different caryological situation.

Ultrastructural Modifications in Cotyledonous Leaves of Ricinus Communis L. During Aging

SUMMARYThe ultrastructural variations observed in Ricinus communis L. cotyledonous leaves during aging have been studied. Various samples up to the 65th day of age, shortly before the fall of the cotyledon itself, were taken. The ultrastructural variations found in various cellular organelles are described. As already observed by other authors in various plants, the most impressive modifications concerned the chloroplasts. Amongst these of particular note is the presence in the senescent cotyledons of vesicles the membranes of which are clearly continuous with those of the thylakoids. These vesicles, which seem to include portions of matrix, draw near to one another absorbing the contacting membranes and seem to give origin to very elongated vesicular formations. The presence inside the vesicles of starch, plastoglobules and DNA fibers supports the hypothesis that portions of matrix are included in them. The plastoglobules of the last samples have various degrees of electron-opacity. It is suggested that ...

Chloroplast Protrusions in Arisarum Proboscideum (L.) Savi

SUMMARYMost chloroplasts in Arisarum proboscideum (L.) Savi show one or two stromatic protrusions, which may be short and thick but also very long and thin. Thylacoids have never been observed in the matrix of these protrusions, whereas small vesicles are often present whose membrane sometimes appears to be continuous with the inner membrane of the chloroplast envelope. Frequently, near to the chloroplast ends, dep hollows are present which include a conspicuous portion of cytoplasm, generally with mitochondria. In many instances, formations with the same structural features as the protrusions are found close to the chloroplasts but separate from them. Such phenomena were observed in sections of leaves of different ages and on isolated chloroplasts as well, both sections and in replicas of freeze-etched samples. The same phenomena, sometimes even in a more striking form, also occur in Arisarum vulgare Targ. Tozz., Arum italicum Mill., A. maculatum L., A. pictum L. f., Dracunculus vulgaris Schott and Zante...

Dati Cariologici Sull'Arisarum Proboscideum (L.) Savi

RIASSUNTOIn apici radicali di Arisarum proboscideum (L.) Savi (Araceae), prelevati direttamente da esemplari di una stazione presso Reggello (Valdarno superiore), e stato trovato un numero cromosomico 2n = 28. Tutti i cromosomi sono eterobrachiali, con centromero submediano; una coppia appare satellitata. Questi dati risultano essere i primi Sulla cariologia del genere Arisarum.

Sondaggi Citogenetici Nelle Polypodiaceae Sensu Stricto

RIASSUNTOVengono indicati i numeri cromosomici aploidi di tre specie di felci appartenenti alla famiglia delle Polypodiaceae « sensu stricto »: Campyloneurum angustifolium Fee: n = 74; Phymatodes scandens (Forst.) Presl: n = 36; Platycerium Hillii Moore: n = 37.Per Campyloneurum, genere fino ad oggi cariologicamente sconosciuto, viene dedotto il numero base x = 37.Vengono confermati i numeri base dei generi Phymatodes (x = 36), e Platycerium(x = 37).

Observations on Nuclear Pores of Freeze-Etched Spore Mother Cells of Psilotum Nudum (L.) Beauv. During Early Stages of Meiotic Prophase I. Preliminary Report

SUMMARYObservation of replicas of freeze-etched spore mother cells of Psilotum nudum (L.) Beauv. has shown that the nuclear envelope undergoes remarkable changes on passing from premeiotic to meiotic stages. Before meiosis, the nuclear envelope shows an even surface covered by randomly distributed pores, whereas in leptotene-zygotene it becomes uneven and wave-like while the pores progressively gather in separate clusters. As a result, wide portions of nuclear envelope devoid of pores are observed at this stage. It is suggested that such events could be originated by traction forces acting on the inner membrane, at early stages of meiosis, and due to motions of the attached chromosome fibers in the course of spiralization and pairing processes. The decrease in average pore frequency in leptotene- zygotene, as compared to the premeiotic stages, is also related, as a first assumption, to the aforementioned traction forces. Quite similar phenomena to those reported for Psilotum nudum (L.) Beauv. were also ob...

Inibitori nel Sarcotesta del Seme di Ginkgo Biloba E loro Azione Rallentatrice Sullo Sviluppo dell'embrione

Abstract Inhibitors in the sarcotesta of GINKGO BILOBA seeds and their retarding action on embryo growth. — The sarcotesta of Ginkgo biloba seeds contains some inhibitors which delay or hamper the germination of other cormophytes seeds. This has been proved with seeds of Hordeum vulgare L., Vicia sativa L., and Triticum vulgare L. germinating in water extracts of ripe sarcotesta at various concentrations. Water extracts of ripe sarcotesta at various concentrations have an anti-mitotic action on root apices of Allium cepa L., resulting in a marked preprophasic inhibition, chromosome stickiness, more or less evident c.-metaphases, and other effects. The water extracts were kept at their original pH (4–4,2) or alkalinized up to a pH of 6,4–6,6. Indirect statistical evidence, which appears to be highly significant if tested with Students t, shows that: i) in the seeds of Ginkgo themselves these inhibitors delay embryo development; ii) in the individual seeds of a same plant the inhibitory capacity of the sar...

Occurrence of Stromacentre in Chloroplasts of Asplenium Trichomanes L.

SUMMARYThe occurrence of stromacentre in chloroplasts of Asplenium trichomanes L. is reported. Such structure, so far described by GUNNING and coworkers in some species of Avena and by FAVALI and MEYER in Ocymum basilicum L, has been found to occur in all stages, from the young to senescent ones, of Asplenium trichomanes. The stromacentre in A. trichomanes is similar in shape to those of Avena sativa and Ocymum basilicum, but differs from these mainly for the size of its component fibrillar units. The value of both diameter and longitudinal periodicity is in fact 85–90 A in Avena and Ocymum, whereas in Asplenium trichomanes values of 170–180 A for the diameter and ca. 110 A for the longitudinal periodicity have been observed. Preliminary investigations on other species of the genus Asplenium have shown that the stromacentre also occurs on chloroplasts of A. viride Huds.

AD FLORAM ITALICAM NOTULAE TAXONOMICAE ET GEOBOTANICAE 7

RIASSUNTO Vengono comunicate diverse nuove stazioni di Arisarum proboscideum (L.) Savi. Viene riportata in Fig. 1 la distribuzione geografica di questa specie, indicando, insieme alle stazioni riferite da MOGGI (1959), quelle trovate da noi e da altri autori dal 1959 a oggi.