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.     

Osservazioni Sullo Sviluppo di Lagurus Ovatus L.

Abstract

Effects of boron and molybdenum on the growth of Asparagopsis armata (Rhodophyceae, Bonnemaisoniales) in culture. - The influence of two trace-metals (boron and molybdenum) on the growth of Asparagopsis armata has been studied in culture. This alga is very tolerant of molybdenum at high concentrations, while boron rapidly becomes toxic.     

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.     

Alcuni Aspetti Citologici Dell'Endosperma di Phaseolus Coccineus L.

Abstract

Some cytological aspects of Phaseolus coccineus L. endosperm. — Cytological observations were made on the endosperm of Phaseolus coccineus, in a limited stage of development of the seed, using different dyes and labelling with ³H-thymidine and ³H-uridine. The results seem to indicate that, contrary to suspensor cells, in the endosperm of Phaseolus, at least in the considered stage, extra DNA synthesis is not present. Chromosomes in these nuclei, however, undergo several endoreduplication cycles. Nucleoli may be either one or more in a cell, and show a characteristic structure. They are often eccentric in the nucleus and extrusions of nucleolar content in the nucleoplasm or cytoplasm are seen. An apparent alternate activity of RNA synthesis in the nucleoli of the suspensor and in those of endosperm cells is discussed.     

Sul Valore del Tessuto di Trasfusione Negli Innesti di “Morus Alba” L.

Riassunto

L'A. illustra la differenziazione di speciali noduli di elementi lignificati nel tessuto di cicatrizzazione, che si forma nell'innesto a becco di luccio del gelso, e mette in rilievo come tali elementi presentino il carattere degli elementi di trasfusione classici delle Gimnosperme, da cui però si differenziano per perforazioni porose sulle membrane. Questo tessuto di trasfusione è da considerarsi come la degenerazione di un legno eteroxilo.     

Embriologia di Ulmus campestris L

Riassunto

L'A. stabilisce die in Ulmus campestris L. lo sviluppo del gametofito femminile avviene secondo due distinti tipi di sviluppo tetramegasporiali bipolarizzati: 1) gametofiti 10, 12 e 14-nucleati con oangio monosporiale che si costruiscono per polarizzazione 1+3 dei nuclei sporiali; 2) gametofiti 8-nucleati con oangio disporiale del tipo Adoxa.

Stabilisce inoltre che la frequenza di sviluppo dei due tipi oscilla intorno ai valori percentuali del 65% e 35% rispettivamente.

Il grado molto elevato di frequenza dei gametofiti 10-nucleati, finora ignoti nella letteratura embriologica, offre all'A. l'opportunità di discutere sul significato e gli attributi del tipo generale Pyrethrum parthenifolium 16-nucleato; il sottotipo Ulmus 10-nucleato, e i sottotipi Tanacetum 12- e 14-nucleato devono esser considerati come sottotipi di riduzione ad esso subordinati.

Durante lo studio della microsporogenesi e dello sviluppo del gametofito femminile è stato riconfermato per questa specie il numero aploide dei cromosomi n = 14. Sono state oservate varie anomalie nella differenziazione dei granuli pollinici, causate da fattori climatici.     

Ricerche Embriologiche sul Genere Thalictrum Embriologia di Thalictrum Angustifolium L. v. flavum L

Abstract

Embriologycals researches in the thalictrum genus. — Embriology of Thalictrum angustifolium L. v. flavum L.

In this research has been studied the development of the female gametophyte of Thalictrum angustifolium L. v. flavum L.; it has been found a tetrasporic bipolarized type: the Pyretrum type, with sixteen nuclei.

The gametophyte is characterized by cellularization of every antipodal nucleus.

Besides this is a new type in the Thalictrum genus, supposing that in others species of this genus, has been recognized the Normal type.

The author supposes another type in this specie, probably a development of the tetrasporic tetrapolarized type, of which he will refer when the necessary elements emerge.

In this specie the microsporogenesis is simultaneous.     

Molecular evidence for hybrid origin of Quercus crenata Lam. (Fagaceae) from Q. cerris L. and Q. suber L.

Abstract

Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Repeats (ISSR) markers were employed to examine samples from Quercus cerris, Q. suber and Q. crenata in order to test the hypothesis of the hybrid origin of Q. crenata from Q. cerris and Q. suber in a part of its distribution area where the two putative parents do not overlap at present. Leaves from 21 Q. crenata and 37 Q. cerris individual trees were collected at natural sites in northern Italy, where Q. suber is currently lacking; 21 Q. suber and six Q. crenata plants from central Italy were also analysed. Results from Unweighted Pair Group Method with Arithmetic mean (UPGMA) analysis and principal component analysis (PCA) implied that exchange of neutral markers has been considerable between the three species, while differences in morphological characters have remained comparatively stable. The Mantel test indicated low correlation between RAPD- and ISSR-based similarity matrices, showing that the two screening techniques reveal unrelated estimates of genetic relationships. Hybrid indices computed for both markers displayed an intermediate position of Q. crenata individuals between the two putative parents shifted toward Q. cerris. Results from the present study corroborate the hypothesis of a hybrid origin for Q. crenata occurring in northern Italy, and suggest asymmetrical backcrossing with Q. cerris acting as the recurrent parent.     

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 Su Vari Casi di Fasciazione in Vitisk Vinifera L.

Summary

The Author describes some cases of bandage of vine branchs and bunchs of grapes in a cultivated vine in the form of a bower. About various cases of natural bandage, he retains that these phenomenons cannot well habe a determined origin but various causes possibly have on influence over the manifestation of these abnormal processes about the susceptibility of some subyects towards forms of deviating development. The vine branch's bandage is for the delineated cases, in correlation to the simultaneous development of two vegetative cones from someone bud, with the following conyoined development with two increased together vine branchs, while the bandage of bunchs of grapes springs from the union of floral secondary aces and from very great activity of the productive organs.     

Formazione di pistilli accessori in “Actaea Spicata“ L.

Summary

One of the most characteristic species of the present Mediterranean vegetation, the holm-oak, still presents in the Appennines, after the alternate glacial periods, relict stations, separated and disjointed, strictly bound to the rocky places.

The Author takes the examination of the altimetrical limits of the holm-oak in Garfagnana (Tuscany), in the valleys of Turrite Secca and Fegana, as a starting point to take into consideration the value and the floristic-oecological aspects of these rocky relicts.

After a climatic and geomorphologic classification of the examined places, the distribution of the holm-oak in the aforesaid valleys is minutely described.

The historical examination shows a derivation of the present plant-communities, rocky and relict, from the dispersion of a presumable anathermic mountain forest, referable to the period of the Quercetum mixtum, rather than to the ancient tertiary, thermophilous and orophilous, Mediterranean forest.

The permanence of the holm-oak in the submontane and mountain stations is strictly bound to their peculiar oecology and its specific temperament. The rocky stations, at least those examined in Garfagnana, are remarkably arid and thermically continental, especially those exposed to the south and south-west. Their aridity, however, helps to lessen the dangers of the frost. The holm-oak can live there in virtue of its tolerance and biological plasticity. To the south it reaches the most elevated heights owing to the protection from cold winds and owing to its greater thermic availability.

A peculiar attention is given to the dynamics, in time and space, of the floral-physiognomical groups: dynamics which has its impulse in the unceasing instability of the rocky micro-places.

Some botanic observation, made in different floral districts, in different conditions of positions, altitude and nature of the substratum, aim at representing the floral aspects of the examined Quercus Ilex-stations.

The flora is constituted with entities fit (preadapted) for the rocky places and with species supplied with remarkable qualities of adaptation. Through the comparisons of the biological spectra, it appears the great fitness of the Chamephytes to the harsh rocky places.

Among the few Mediterranean species able to follow the holm-oak in the rocky localization it is worth mentioning, above all, the Juniperus phoenicea L., species typically of the littoral, never noticed in Tuscany at such elevated heights as those which have been noticed, as it appears in this work, in the Apuane Alps (till 1200 metres).     

Caratterizzazione citologica e citochimica del nefrone di Cyprinus carpio L.

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

Assorbimento di saccarosio in ipocotili di ravanello (Raphanus sativus L.)

Abstract

In questo lavoro abbiamo determinato le caratteristiche di entrata del saccarosio in funzione della sua concentrazione esterna, incubando i pezzi in saccarosio triziato, in condizioni normali e di stress osmotico. Nelle parti apicali l'assorbimento di saccarosio esogeno è lineare in presenza di basse concentrazioni mentre non lo è ad alte concentrazioni. Per quanto riguarda le parti basali la linearità si mantiene per tutte le concentrazioni; inoltre nelle parti apicali l'assorbimento è maggiore che nelle basali e la differenza aumenta all' aumentare delle concentrazioni di saccarosio esterno. Abbiamo poi studiato l'assunzione di saccarosio con osmotici diversi in cui fosse presente anche saccarosio marcato. I risultati ottenuti dimostrano che le parti apicali stressate prendono meno saccarosio dei controlli, mentre nelle basi stressate l'assorbimento, pur essendo inferiore a quello degli apici, è superiore rispetto ai controlli. Le differenze nel trasporto del saccarosio negli apici e nelle basi potrebbero essere spiegate dal fatto che a parità di peso nelle zone apicali ci sono più cellule di dimensioni inferiori che non hanno completato la distensione cellulare e che essendo in attiva crescita sono metabolicamente più attive. Nelle zone basali è invece presente un maggiore numero di cellule morte (xilema completamente differenziato). Questi due fattori potrebbero determinare nelle parti apicali un maggiore assorbimento con prevalenza del trasporto attivo e nelle parti basali un assorbimento inferiore con prevalenza del trasporto per diffusione.