摘要:

Ricerche infrastrutturali sui plastidi delle piante parassite. IV. Entomocecidi di«Cuscula australis». Le galle che si formano nei fusti diClscuta australisin seguito a deposizione di uova da parte di un Curculionide galligeno,Smicronyx, sono state studiate dal punto di vista morfologico, fisiologico ed ultrastrutturale; infatti queste galle presentano un aspetto esterno note-volmente diverso, e nettamente più verde, rispetto a quello dei fusti non parassitati. In accordo con l'aspetto macroscopico il contenuto in clorofilla totale risulta nelle galle quintuplo rispetto a quello dei fusti; inoltre il rapporto tra clorofilla a e clorofilla b si avvicina, nel caso delle galle, a quello riscontrabile nelle piante normalmente verdi, a differenza di quanto invece si registra per i fusti normali diCuscuta.In accordo con quanto dimostrato in lavori precedenti, circa l'azione antagonista dell'acido ascorbico su quelle esercitate dall'acido indolacetico, si è notato che i tessuti a maggior contenuto in clorofilla possiedono pure un maggior contenuto in acido ascorbico. Infatti il contenuto in acido ascorbico è risultato circa doppio nelle galle (707 γ per grammo di peso fresco) rispetto a quello dei fusti (342 γ per grammo di peso fresco). Ciononostante l'attività ascorbico-ossidasica nei due organi studiata è risultata uguale. L'esame del contenuto dei diversi aminoacidi nelle galle e nei fusti ha messo in evidenza solo lievi differenze, ad eccezione di quella riguardante il contenuto in triptofano, noto come l'aminoacido precursore dell'acido indolacetico. Il contenuto in triptofano risulta minore nelle galle dove raggiunge la concentrazione di 120 γ per grammo di peso fresco, mentre è contenuto in maggior copia nei fusti, dove raggiunge i 220 γ per grammo di peso fresco. Il maggior contenuto in clorofilla ha avuto inoltre corrispondenza in una fissazione fotosintetica dell'anidride carbonica nella galle che risulta quintupla rispetto a quella che avviene in condizioni di oscurità, mentre i fusti non parassitati fissano alla luce anidride carbonica in quantità superiore solo del 23% rispetto a quanto avviene nei fusti posti al buio. L'ultrastruttura dei plastidi risulta nettamente diversa nelle tre zone in cui può essere suddivisa la galla: nella zona più esterna di colore giallastro, i plastidi mostrano soltanto alcune vescicole allungate talvolta appaiate a formare grani molto primitivi, alcune granulazioni scure, interpretabili come addensamenti di carotinoidi, e grossi granuli d'amido. Nella zona più interna, che risulta di colore verde intenso, i cloroplasti invece mostrano un sistema lamellare molto sviluppato, organizzato in grani formati da numerosi tilacoidi collegati da lamelle stromatiche, relativamente poche granulazioni scure e pochi granuli d'amido in genere di dimensioni ridotte. Nella zona intermedia, di colore verde pallido, la ultrastruttura dei plastidi presenta, sia pure con qualche variabilità, caratteristiche intermedie fra quelle della zona esterna e quelle della zona più interna. Quando le galle si trovano in condizioni microambientali particolari (per esempio fortemente ombreggiate) l'ultrastruttura dei plastidi della zona più esterna mostra particolari diversi da quelli prima descritti. Sembra che il minor contenuto in clorofilla ed il minore sviluppo ultrastrutturale dei cloroplasti della zona più esterna della galla rispetto a quelli della zona più interna dipenda dall'azione clastica esercitata dalla luce sulk clorofilla nei tessuti diCuscuta australised a questa conclusione portano anche altre ricerche attualmente in corso. Particolare degno di nota è che la membrana delimitante i plastidi di tutte le zone della galla risulta costituita da quattro membrane ravvicinate due a due. Da questi risultati sembra di poter concludere che i tessuti diCuscuta australis, sottoposti ad uno stimolo adeguato, sono capaci di sintetizzare quantità anche notevoli di clorofilla, in grado di fissare fotosinteti-camente l'anidride carbonica alla luce ed organizzata in cloroplasti che si differenziano in modo simile a quanto avviene nelle plante normalmente verdi.

ISSN:0017-0070    

DOI:10.1080/11263506809426687

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A list of Italia Myxomycetes.In this work 41 species, 13 of which new to Italy, are named. The specimens were collected chiefly in Valtellina (province of Sondrio), in Lombardy, in Emilia and Romagna, and in Abruzzi. Most of the specimens found already had fruiting bodies; in some cases these were obtained by means of a culture in a moist chamber of bark or dead wood gathered in the fields.

ISSN:0017-0070    

DOI:10.1080/11263506809426688

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Researches at the optical and electron microscopes on quiescent vegetative apices of«Psilotum nudum» (L.)Beauv. cuttings.Small aerial branches ofPsilotum nudumhave been planted in sand and kept in a very humid hothouse. None of them has rooted and no noticeable growth occurred. However the cuttings have remained vital during three years and one month until the moment that is when the last one was utilized for our researches. These cuttings and some other ones planted at a later date were utilized for a study of the quiescent vegetative apices at the optical and electron microscope. Material was collected 15 days, one month, three months, one year, two years, two and a half year, and three years and one month after planting. We have noticed a progressive thickening of the cell walls, reabsorption of the plasmodesmata and a separation of the individual cells which were no longer kept together by the middle lamella: all these changes bring about a kind of encystment of the apical cells. We have also observed a progressive accumulation of starch grains in the chloroplasts until the cells appeared absolutely full of starch. In the two years, and the three years and one month old cuttings a gradual decrease of the starch content occurred, especially in the cells nearest to the stem tip. We are led to think that the exceptional capacity for survival which distinguishesPsilotum nudumcould be explained to a large extent by the attainment of the « encysted » condition of its apical cells together with their capacity of storing a great quantity of starch.

ISSN:0017-0070    

DOI:10.1080/11263506809426689

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Studying the mycological flora of paddy and grass-fields we had the opportunity to isolate some species of Eutotiaceae which are of particular interest. Three species were not yet known in Italy and only one was found in a soil of mountain pasture. The last one is also common in paddy fields. One of the isolated species was aPseudoeurotiumvan Beyma, ascomycete with asci containing 16 ascospores, not identifiable with the systematically related species described asPseudoeurotium indicum(Chattopadhyay and Das Gupta) Chattopadhyay from « oryzetis » in India andPseudoeurotium multisporum(Saito and Minoura) Stolk in Japan. Some distinct morphological differences exist between our isolates andP. multisporum;but they differ only faintly fromP. indicum:that is our isolates have pedicellate asci. Therefore we suggest the new variety:Pseudoeurotium indicum(Chattopadhyay and Das Gupta) Chattopadhyay var.orizetorumnobis. Three species of the genusEmericellopsisvan Beyma:E. minimaStolk,E. terricolavan Beyma andE. humicola(Cain) Cain were also isolated. The first one from the paddy-fields and the last two, not yet described in Italy, from grass fields. The possible relationship betweenE. minimaStolk aridE. pusillaMathur, Sukapure and Thirumalachar has been discussed.

ISSN:0017-0070    

DOI:10.1080/11263506809426690

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Spermine and spermidine in seeds.A study on spermine and spermidine distribution and their ratio was carried out on seeds of 57 species belonging to different families of higher plants in particular to Papilionaceae. These two polyamines were found in all the species examined and the mayority have a lower than one ratio (spermine/spermidine). In the tribe of Phaseoleae (Papilionaceae), however a greater than one ratio was found in three genera:Phaseolus, DolichosandErythrina.This modified ratio was not found in the other two genera examined of this tribe (VignaandGlycine)neither in the nearest tribe of Vicieae. This could be a confirmation of the close relationship existing between these three genera which has already been established on a morphologic basis.

ISSN:0017-0070    

DOI:10.1080/11263506809426691

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Effects of growth retardants on oxidative phosphorylation and on cyclic photophosphorylation.The effects of some growth retardants on energy interconversion mechanisms has been studied. It has been reported that Amo 1618 and CCC greatly inhibit oxidative phosphorylation in isolated pea mitochondria. The inhibition of Pi esterification is higher than the oxygen uptake using succinate; this suggests a weak uncoupling effect. However substituting succinate with malate the inhibition of oxygen consuption approaches that of Pi esterification so that the uncoupling effect is quite dubious. On the other hand Amo 1618 does not stimulate oxygen uptake of mitochondria in « state 4 ». For this reason it is not possible to consider growth retardants definitely uncoupling agents, as Heatherbell et al. suggest, and it will be necessary to clarify this point using more appropriate techniques. It has been reported that Amo 1618 and CCC do not inhibit cyclic photophosphorylation with phenazine or FMN in isolated spinach chloroplasts. The data suggest that oxidative phosphorylation inhibition is a peculiar characteristic of growth retardants. The inhibitory effect on oxidative phosphorylation is obtained with concentrations lower than the « in vivo » concentrations required to produce the typical effects of growth retardants. The possibility that the action of growth retardants « in vivo » is due to the lowering of ATP in the cell in relation to the inhibition of Pi esterification has been discussed.

ISSN:0017-0070    

DOI:10.1080/11263506809426692

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Respiratory and metabolic changes in germinating seeds of«Cucurbita maxima». The general metabolic behaviour of isolated cotyledons and embryonic axes ofCucurbita maximavar. Mammouth was investigated. I) In cotyledons isolated from seeds during the early phases of germination, we observed: a) a significant increase of Qo2during germination; b) a fall of the R.Q. value from ca. 0.8 to values lower than 0.6, suggesting a respiratory utilization of lipids as well as a conversion of lipids into carbohydrates through the glyoxylate cycle; c) a clear decrease in the amount of total fatty acids during germination, reaching a value of 3095 after 48 hours of germination; d) a progressive decrease in the content of acid-hydrolizable polysaccarides and principally of sucrose. On the contrary, the level of free reducing sugars increased, reaching at 72 hours of germination a value of eleven times the initial value; e) an increase of the free aminoacids content from 48thto the 72thhour of germination. II) In the embryonic axes isolated from 48 hours germinating seeds, after 7 hours incubation in water, we observed: a) a decrease of R.Q. from ca. 0.8 to 0.7–0.65; b) a fall close to 50% in the sugars content; c) a very marked decrease (ca. 8795) in the level of total fatty acids The results of the present study show that after the first 24 hours of germination a respiratory utilization of lipids storage occurs. The R.Q. value suggest a conversion of lipids into sugars.

ISSN:0017-0070    

DOI:10.1080/11263506809426693

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue

ISSN:0017-0070    

DOI:10.1080/11263506809426686

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor