1,721,030 research outputs found
Effetti della monensina sulla forma a lievito miceliare di Candida albicans (Robin) Berkhout
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In an ancient vascular plant the intermediate relaxing component of NPQ depends on a reduced stroma: Evidence from dithiothreitol treatment
No full textIn plants, the non-photochemical quenching of chlorophyll fluorescence (NPQ) induced by high light reveals the occurrence of a multiplicity of regulatory processes of photosynthesis, primarily devoted to photoprotection of photosystem I and II (PSI and PSII). The study of NPQ relaxation in darkness allows the separation of three kinetically distinct phases: the fast relaxing high-energy quenching qE, the intermediate relaxing phase and the nearly non-relaxatable photoinhibitory quenching. Several processes can underlie the intermediate phase. In the ancient vascular plant Selaginella martensii (Lycopodiophyta) this component, here termed qX, was previously proposed to reflect mainly a photoprotective energy-spillover from PSII to PSI. It is hypothesized that qX is induced by an over-reduced photosynthetic electron transport chain from PSII to final acceptors. To test this hypothesis the leaves were treated with the reductant dithiothreitol (DTT) and the chlorophyll fluorescence changes were analysed during the induction with high irradiance and the subsequent relaxation in darkness. DTT treatment caused the well-known decrease in NPQ induction and expectedly resulted in a disturbed photosynthetic electron flow. The relaxation curves of Y(NPQ), formally representing the quantum yield of the regulatory thermal dissipation, revealed a DTT dose-dependent decrease in amplitude not only of qE, but also of qX, up to the complete disappearance of the latter. Modelling of the relaxation curves under alternative scenarios led to the conclusion that DTT is permissive with respect to qX induction but suppresses its dark relaxation. The strong dependence of qX on the chloroplast redox state is discussed with respect to its proposed energy-spillover photoprotective significance in a lycophyte
Effects of long-term light acclimation on Photosystem II functional antenna size and excitonic connectivity in Selaginella martensii.
No full textLycophyte division is composed of ancient vascular plants that diverged from euphyllophyte lineage ca. 400 million years ago. Among these, Selaginella martensii Spring has evolved to inhabit shade environments of tropical-equatorial rainforests. However, this plant is also able to acclimate efficiently to light regimes as different as deep shade and full sunlight (Ferroni et al. 2016, 2021). Such characteristic reveals a marked flexibility of the photosynthetic machinery in response to the light availability, but the underlying structural and dynamic acclimation features have been clarified only partially. In fact, differently from most seed plants, S. martensii is unable to modulate the content of Photosystem II antenna complexes (LHCII), which remains constant from deep shade to full sunlight regime, while the ratio between PSII and PSI decreases. In order to clarify the light acclimation features in S. martensii under deep-shade (L), intermediate shade (M) and full sunlight (H), we analyzed some functional aspects of light harvesting and electron transport after the plants' exposure to dark for 20 minutes, far red (FR) light for 20 minutes and moderate light for 1 hour. The analysis was performed using a HandyPEA (Hansatech, UK) fluorometer, which allowed us to calculate the JIP-test parameters. Among these, we particularly focused on ABS/RC, i.e. the functional antenna size of a PSII unit (Stirbet and Govindjee 2011). We also used the fluorescence transients to calculate the PSII excitonic connectivity parameters, which describe the probability of excitation transfer between different PSII units (Stirbet 2013). Our results suggest that the acclimation to different light regimes influences both PSII functional antenna size and PSII connectivity, but the direction of changes apparently contrasted with expectations. On one hand, the PSII antenna size was only slightly variable from L to H plants. On the other hand, PSII connectivity was in general far lower when compared to common values reported for seed plants. Especially H plants reported connectivity values close to 0, suggesting a "puddle" organization of PSII
Fondamenti di Botanica Generale - teoria e pratica in laboratorio. Seconda Edizione.
No full textIl presente manuale, giunto alla seconda edizione, è rivolto principalmente agli studenti dei Corsi di Laurea in cui è previsto un insegnamento di Botanica Generale.
Il volume si focalizza sui principi di base della materia con una trattazione approfondita di Citologia, Istologia e Anatomia delle piante, a cui si aggiungono utili nozioni sui principali gruppi di organismi vegetali.
Alla fine di ogni capitolo sono presenti alcuni Spunti di Riflessione: si tratta di semplici quesiti o brevi annotazioni che aiutano lo studente a collegare il materiale di studio con aspetti di tipo sia evolutivo sia applicativo.
Il testo si caratterizza per l’uso di un linguaggio semplice ma rigoroso e si avvale di un ampio apparato iconografico composto da fotografie ottenute da preparati “a fresco”, che riproducono ciò che effettivamente lo studente può osservare durante la parte pratica del corso di Botanica. A queste si aggiungono numerosi schemi in grado di svolgere un’importante azione esemplificativa delle microfotografie, che potrebbero risultare poco chiare a un occhio ancora inesperto. Tutte le immagini a colori sono disponibili sul sito web tramite codice QR.
L’elemento più innovativo dell’Opera consiste nell’aver integrato i concetti teorici con la parte sperimentale: alla fine di molti capitoli, infatti, sono proposti semplici Esperimenti di laboratorio, per affrontare i quali sono state riportate in Appendice le norme relative alla sicurezza nei laboratori, nonché alcuni protocolli di base. Gli studenti potranno così approfondire le nozioni teoriche riportate nel testo, riproducendo, in tal modo, la prassi attuata per l’insegnamento di Botanica. Per valorizzare questo aspetto del testo, nella seconda edizione le schede di laboratorio sono accompagnate da alcuni video che riproducono gli Esperimenti svolti in laboratorio, documentandoli passo passo: i video sono disponibili sul sito web tramite codice QR
Growth and lipid synthesis promotion in mixotrophic Neochloris oleoabundans (Chlorophyta) cultivated with glucose
No full textIn the recent years, the studies concerning the cultivation
of Neochloris oleoabundans for biofuel purposes have
increased, in relation to its capability to accumulate lipids when grown under nutrient starvation. Unfortunately, this cultivation mode does not allow to reach high biomass densities, which are required to improve the feasibility of the process. Increasing knowledge of the microalgal physiology is necessary to obtain new useful information for the improvement of culture performance in the perspective of large-scale cultivation. In this work, the mixotrophic cultivation of N. oleoabundans in a brackish
medium added with different glucose concentrations has been
tested under shaking, with the aim of stimulating growth alongside
lipid accumulation inside cells. Cell morphology, glucose
consumption, photosynthetic pigment content and photosynthetic
efficiency were also investigated. Among all tested glucose
concentrations (0–30 g L−1), it was observed that 2.5 g L−1
was the optimal concentration, allowing to obtain the best
compromise between glucose supplement, biomass production
and lipid accumulation. Growth was highly enhanced in
mixotrophic cultures, linked to the release of cells from sporocysts.
A unique feature characterising mixotrophy in N.
oleoabundans was the promotion of the maximum quantum
yield of Photosystem II. Moreover, when mixotrophic cells
entered the stationary phase, high lipid accumulation was
induced. This study shows that the addition of glucose to
N. oleoabundans remarkably increases the production of biomass
enriched in lipids and represents an advancement for the
cultivation of this microalga for applied purposes
Interaction of monensin on dimorphic transition and hyphal growth in Candida albicans
No full textMonensin, an exocytosis perturber, was assayed on the dimorphic fungus Candida albicans in order to study its effects on wall synthesis and morphogenesis. In the presence of the drug, both germ-tube formation and hyphal elongation were markedly inhibited according to the dose and exposure time. The effect was accompanied by morphogenetic malformations which could be detected under UV light and by transmission electron microscopy. Enormous wall and septa thickenings revealed by cytochemical tests indicated an abnormal deposition of chitin. Since chitin synthase is inserted in the plasma membrane in a latent state and its activation depends on regulatory factors reaching the cell periphery through an orderly exocytosis, it is assumed that monensin affects the vesicular traffic leading to a prevalence of activators over inhibitors of the enzyme
INtech4Water “INtegrated TECHnologies for pollutants in (waste) WATER services"
No full textINTECH4WATER è un progetto che ha come obiettivo la depurazione, la valorizzazione e il riciclo di acque reflue provenienti da depuratori municipali e da processi industriali, in ottica di Circular Economy.
Il progetto prevede una integrazione di tecnologie innovative, sicure e sostenibili, per l’eliminazione dei contaminanti più comuni delle acque reflue (carichi di N e P, inquinanti emergenti, microplastiche, batteri patogeni per l’uomo).
Le tecnologie previste per la sperimentazione sono: filtri ceramici, fotocatalitici e adsorbenti, processi di ossidazione avanzata, UV, ozono e microalghe. Il progetto prevede due fasi: fase 1) di laboratorio, per identificare la migliore combinazione di tecnologie; fase 2) prototipale, per uno scale up delle ricerche e per testare il sistema su scala reale.
Tutti gli step saranno guidati da analisi statistiche avanzate (machine learning e intelligenza artificiale) e corredate da analisi chimiche, biologiche e microbiologiche.
L’idea di creare un nuovo sistema di tecnologie integrate per la depurazione, la valorizzazione e il riciclo di acque reflue di depuratori municipali e processi industriali ha l’obiettivo di migliorare l’efficienza del processo di rimozione degli inquinanti più comuni, chimici e biologici.
Il progetto INTECH4WATER è rivolto specialmente a realtà aziendali con elevata variabilità, nel corso dell’anno, della composizione del refluo, per cui una sola tecnologia di depurazione non può essere in grado soddisfare appieno la depurazione delle acque in uscita dagli impianti.
La possibilità di rendere più efficiente l’intero processo depurativo garantisce una migliore qualità delle acque rilasciate in corpi idrici naturali, con conseguente maggiore tutela della salubrità dell’ambiente e con un’evidente ricaduta positiva sulla salute umana
Photosystem II photoinhibition and photoprotection in a lycophyte, Selaginella martensii
No full textThe Lycophyte Selaginella martensii efficiently acclimates to diverse light environments, from deep shade to full sunlight. The plant does not modulate the abundance of the Light Harvesting Complex II, mostly found as a free trimer, and does not alter the maximum capacity of thermal dissipation (NPQ). Nevertheless, the photoprotection is expected to be modulatable upon long-term light acclimation to preserve the photosystems (PSII, PSI). The effects of long-term light acclimation on PSII photoprotection were investigated using the chlorophyll fluorometric method known as “photochemical quenching measured in the dark” (qPd). Singularly high-qPd values at relatively low irradiance suggest a heterogeneous antenna system (PSII antenna uncoupling). The extent of antenna uncoupling largely depends on the light regime, reaching the highest value in sun-acclimated plants. In parallel, the photoprotective NPQ (pNPQ) increased from deep-shade to high-light grown plants. It is proposed that the differences in the long-term modulation in the photoprotective capacity are proportional to the amount of uncoupled LHCII. In deep-shade plants, the inconsistency between invariable maximum NPQ and lower pNPQ is attributed to the thermal dissipation occurring in the PSII core
Embolizzazione distale del trombo endoventricolare sinistro con stroke ischemico in corso di trombolisi tardiva nell'infarto miocardico acuto
No full textEmbolizzazione distale trombo endoventricolare sinistro con stroke ischemico in corso di trombolisi tardiva nell'infarto miocardico acut
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