1,721,016 research outputs found
Histochemistry of cytoplasmic reserves in excipular hyphae of Catillaria bouteillei (Desm.) Zahlbr.
No full textVengono descritte attraverso l'indagine istochimica le fasi di accumulo e mobilizzazione delle riserve in un corpo fruttifero di un ascolichene foliicol
Premiere station en Italie d'un lichen foliicole
No full textViene segnalata la prima stazione italiana di un lichene cristoso foliicolo su Buxus semperviren
A SEM study of injury symptoms in Parmotrema reticulatum treated with paraquat or growing in sulphur dioxide-polluted air
No full text
Histochemistry and generic delimitation in Parmelia and Punctelia
No full textAttraverso la carettirizzazione istochimica dello strato corticale dei generi Parmelia e Punctelia viene proposto un nuovo carattere utile per la delimitazione dei due tax
Preliminary evidence for a cholinergic-like system in lichen morphogenesis
No full textMembrane acetylcholinesterase activity is considered to be a marker for a cholinergic system. When temporarily expressed in differentiating cells other than the nervous or muscular ones, it may play a role in morphogenesis. In the lichenParmelia caperata (L.) Ach., acetylcholinesterase is histochemically localized mainly in the cell walls and/or membranes of both symbionts just where they proliferate and form well-organized propagation structures, the soredia. The enzyme activity is first detected in a few algae undergoing aplanosporogenesis and later in medullary hyphae that reach the dividing algae by elongating perpendicularly to the thallus surface. This histochemical pattern that is associated with algal proliferation and oriented hyphal growth is characteristic of early morphogenesis of the soredia; when fully differentiated, they consist of an inner dividing alga and an outer hyphal envelope, both showing cholinesterase activity. Substrate specificity and inhibitor sensitivity of the histochemical staining indicate an acetylcholinesterase-like activity. However, extracts of the thallus areas where soredia develop give four bands of cholinesterase activity on disc electrophoresis: the two cathodal bands have the characteristics of acetylcholinesterase, the others of pseudocholinesterase. One of the latter hydrolyses propionylthiocholine very rapidly. The findings suggest that in lichen symbiosis, a cholinergic-like system participates in regulating morphogenetic processes such as cell division, oriented tip growth and alga-fungus membrane interactions. Environmental stimuli, particularly light, might trigger the development of soredia by modulating the activity of the cholinergic mechanism
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