1,721,021 research outputs found
Coordinate control by Mg2+ of the phosphorylative activities and of the succinate dehydrogenase of higher plant mitochondria
No full textThe role of free Mg2 and its chelated forms as a fine mechanism to control succinate dehydrogenase (SDH) and
the phosphorylative activities, in particular that of H-PPiase, of pea stem mitochondria was examined. Free
pyrophosphate (PPi) was found to be a competitive inhibitor of SDH in sub-mitochondrial particles (SMP), but this
inhibition was relieved when PPi was chelated by Mg2. Neither Mg2 alone in SMP, nor Mg2 depletion in intact
mitochondria affected SDH activity. Chelation of Mg2 by ATP, ADP, EDTA or citrate restored PPi-induced
inhibition of SDH activity. Being (Mg)PPi or (Mg)2PPi the substrate of the H-PPiase, the subtraction of Mg2 from
this complex by stronger chelators, such as ATP or ADP, liberates free PPi causing an inhibition of the H-PPiase
activity. In particular, the formation of the (Mg)ADP chelate could favor the H-ATPase, being its substrate.
Therefore, the activities of SDH, H-PPiase and H-ATPase appear to be interconnected and regulated by the
equilibrium between free Mg2 and its chelates with PPi, ADP and ATP
Respiratory burst activity in late pregnancy in carrier of x-linked chronic granulomatous disease
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Instability of Casalabate village (Lecce, Italy): Analisys of risk conditions
No full textIl borgo di Casalabate, frazione marina di Lecce sita sulle sponde
del Mar Adriatico, è stato interessato da notevoli fenomeni di dissesto
con crollo di alcune abitazioni ed inagibilità di varie altre. Per indagarne
le cause è stato condotto un dettagliato piano di indagini multidisciplinari,
costituito da un rilievo geologico integrato dalla trivellazione
di 23 sondaggi e da una indagine georadar nonché da analisi
chimico-fi siche, carotaggi termosalinometrici e misure di velocità di
fi ltrazione sulle acque di falda. Si è così potuto defi nire che i litotipi
presenti nella maggior parte del territorio sono ascrivibili a depositi
di Duna fossile, rappresentati da calcareniti irregolarmente cementate
rinvenibili fi no a 4-9 m sotto il livello mare, ma di qualità fi sico-meccanica
prevalentemente scadente e variabile dal luogo a luogo; al di
sotto dei depositi dunari fossili seguono depositi francamente marini
rappresentati da biocalcareniti e biocalciruditi di colore biancastro,
riccamente fossilifere e irregolarmente cementate. Non sono state
rilevate cavità e/o condotti riconducibili a fenomenologie di dissoluzione
paracarsica, mentre sussiste un’elevata variabilità litologica,
sia in senso verticale che orizzontale, dei terreni su cui poggiano le
fondazioni degli edifici.
Le acque sotterranee, con carichi idraulici oscillanti fra i 30 cm e
gli 80 cm s.l.m., defl uiscono liberamente a mare e presentano la tipica
stratifi cazione salina degli acquiferi costieri con valori di salinità
crescenti, nel giro di 5-6 m, da pochi mg a 3-4 g/l; il defl usso a mare,
inoltre, esclusivamente orizzontale interessa principalmente solo alcuni
livelli dunari con velocità di fi ltrazione,Vf , di circa 250 cm/g.Nel complesso, le indagine hanno evidenziato che, contrariamente
a quanto era stato ipotizzato, i fenomeni di dissesto statico non
sono imputabili al cedimento della volta di cavità ipogee, ma all’incidenza
e al concorso dei seguenti fattori: le cattive e, in alcuni casi,
pessime caratteristiche geotecniche dei terreni di fondazione degli
edifi ci; la mancata preventiva caratterizzazione geotecnica degli stessi
e la conseguente inadeguatezza strutturale delle tipologie di fondazione
adottate; l’immissione nel sottosuolo di acque pluviali che
hanno determinato il dilavamento e l’asportazione della frazione fi ne
dei terreni di fondazione.Casalabate is an outlying ward of Lecce located on the Adriatic Sea shore, over the time this small village has undergone remarkable hydrogeologic disturbance resulting in the collapse of some dwellings and the condemn of many others. In order to find out the causes, an accurate multidisciplinary investigation planning has been implemented. This includes a geological survey with 23 boreholes, a georadar investigation, as well as chemical-physical analyses, thermo-saline logging and groundwater flow velocity measurements. The above led to the determination that lithotypes in most territory are related to fossil Dune deposits, formed by irregularly cemented calcarenites which can be found up to 4-9 m below sea level whose physical-mechanical quality is basically poor and varies from place to place. Beneath fossil dune deposits, pure marine deposits of abundantly fossiliferous and irregularly cemented whitish biocalcarenites and calcirudites are encoutered. No cavity and/or channel associated with parakarstic dissolution phenomena has been found, but grounds underlying the foundations of buildings greatly vary in their lithologic structure both vertically and horizontally. Groundwater, whose hydraulic heads range from 30 cm and 80 cm a.s.l., flows unimpeded to the sea and shows the typical saline stratification of coastal aquifers with salinity values which, in the space of 5-6 m, increase from a few mg to 3-4 g/l. Moreover, the exclusively horizontal outflow to the sea takes place only through some dune levels whose groundwater flow velocity, Vf, is about 250 cm/g. As a whole, investigations proved, contrary to the assumptions, that static disturbance phenomena cannot be due to the collapse of the underground cavities vault, but because of the incidence and combination of the following factors: poor, and in some cases, very poor geotechnical characteristics of foundation grounds; the lack of a preliminary geotechnical characterization of buildings leading to the choice of improper practice in laying down foundations; the letting of rainwater into the subsoil which caused the leaching and the removal of the fine fraction of the foundation grounds
Effect of trifluralin synthesis intermediates on plant cell membrane permeability and growth of plants and fungi.
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