Showing papers by "Gian Gabriele Franchi published in 1984"

Pollen grain viability in Parietaria judaica L. during the long blooming period and correlation with meteorological conditions and allergic diseases

Abstract: Pollen grain viability and starch presence in pollen were followed during the long blooming period (May-November) of Parietaria judaica, the most widespread pellitory in Italy, responsible for many cases of allergic diseases. Observations were carried out near Siena (Tuscany), in the years 1978 and 1979. Viability is high in late spring and early autumn, and pollen grains are starchy. The presence of starchless grains is always related to low viability: a production of pollen with a low viability occurs at the beginning and end of blooming, and also in summer, during drought periods. Pollen grain viability varies widely during the blooming period, and its variations are correlated to meteorological conditions, mainly rainfall and temperature. Allergic diseases due to pellitory, however, are mainly reported between April and July, and on the other hand a small amount of patients states that they suffer all the year round. The discrepancies between the periods of viable pollen production and of dec...

Reproduction in Mediterranean plants

Abstract: The authors consider sexual reproduction in Mediterranean Angiosperms and Gymnosperms and its connections with some environmental factors. Firstly it is examined the monthly distribution of the blooming periods: out of the 666 considered Angiosperm species, most of which remain in bloom over several months, 518 bloom during May and 495 during April, whilst less than 100 species bloom from September through February. It is then considered the reproductive cycle—from blooming to seed dispersal—which is very short in most of the plants. However the authors examine in detail also the cycles of species commonly considered representative for the Mediterranean area (Pinus halepensis Mill., P. pinea L., P. pinaster Aiton, Quercus macrolepis Kotschy, Q. suber L., Q. coccifera L. and Arbutus unedo L.), but in which the reproductive cycles last one year or more. It is also described a short cycle, the cycle of Cytinus hypocistis L. with its peculiar environmental devices. Finally the effects are predicted o...

« Harmomegathy »: Un problema aperto e misconosciuto

Abstract: « Harmomegathy »: a still open problem not yet well-known. - Wodehouse used the term « Harmomegathy » to indicate the form and volume change in pollen grains, due to water loss or assumption. Roundish and tricolporate grains in the anther become oval and decrease in volume during the dehydration preceeding anthesis. Viceversa during rehydration on the stigma they undergo the opposite process. Pollen water content at an thesis varies from species to species and it usually ranges between 10 and 20%; nevertheless in some families as Zingiberaceae and Araceae it is higher. Anther and pollen dehydrations are affected by environmental factors, such as humidity of air and temperature, before the anthesis and when pollen is suspended in air. Besides, to avoid the further loss of water during pollen flow, an oily layer derived from tapetum degeneration is deposited outside the pollen grains. During dehydration and rehydration pollen grains undergo a stress due to shape and volume changes expecially in the...

High performance liquid chromatography separation of the intermediates of pyridine coenzymes metabolism in Ricinus communis L. seedlings.

Abstract: The metabolism of pyridine coenzymes is not yet well clarified in vegetable cells. We propose a HPLC method to separate the compounds involved in the pyridine nucleotides cycle in less than 32 min. The method has been applied to Ricinus communis seedlings. On the basis of the results obtained, the well known "de novo" and "salvage" pathways, demonstrated in other biological tissues for NAD biosynthesis, are likely to occur in this vegetable system.