1,529 research outputs found
Short host-defence peptides from frog skin
No full textGene-encoded antimicrobial peptides (AMPs) are key components of the innate immune response of all pluricellular organisms, providing them with the first-line defence against pathogens [1-4]. Amphibian skin secretions represent one of the richest natural sources for such molecules, which are synthesized and stored within granules of holocrine-type serous glands and released upon stimulation [5-7].We are studying two major groups, temporins and bombinins H. Temporins constitute a large family of AMPs (more than 40 members) isolated from the skin of the genus Rana, and are among the smallest amphipathic a-helical peptides (10-14 residues) found in nature to date, and with the lowest number of positively charged amino acids [8,9]. Interestingly, some temporins (A, B and L) do possess attractive and unique properties that make them promising candidates for the future design of anti-infective agents with new modes of action, urgently needed due to the increasing resistance of microorganisms to the available drugs. These properties include: (i) a fast membranolytic effect against a large spectrum of pathogens (bacteria, fungi and protozoa of Leishmania genus including both the insect and the mammalian stages of the parasite) [10,11]; (ii) preservation of biological activity in serum and in physiological salt concentration [11]; (iii) chemotactive activities on human phagocytes; (iv) synergistic action when combined with conventional antibiotics [12]; (v) in vivo efficacy in preventing prosthetic graft infections and lethality in rat models of septic shock. The second interesting family of AMPs refers to bombinins H, isolated from amphibia of Bombina genus [13] and containing isomers with a single D-amino acid which results from a post-traslational modification. By studying these peptides [14],we have demonstrated the importance of a single L- to D epimerization as a new approach developed by nature to modulate not only the bio-availability (e.g. higher solubility) and biostability (i.e. protection from proteolytic degradation) of these molecules, but also their biophysical properties (peptide structure and organization within membranes) and antimicrobial activities [15].
REFERENCES
[1] Boman H.G. Peptide antibiotics and their role in innate immunity. Annu. Rev. Immunol. 1995; 13:61-92.
[2] Kimbrell D.A. and Beutler B. The evolution and genetics of innate immunity. Nat. Rev. Genet. 2001; 2:256-267.
[3] Ganz T. Defensins: antimicrobial peptides of innate immunity. Nat. Rev. Immunol. 2003; 3:710-720.
[4] Selsted M.E. and Ouellette A.J. Mammalian defensins in the antimicrobial immune response. Nat. Immunol. 2005; 6:551-557.
[5] Barra, D., and Simmaco, M. Amphibian skin: a promising resource for antimicrobial peptides, Trends Biotechnol. 1995; 13: 205-209.
[6] Bevins, C. L., and Zasloff, M. Peptides from frog skin, Annu. Rev. Biochem. 1990; 59:395-414.
[7] Mangoni, M. L., Miele, R., Renda, T. G., Barra, D., and Simmaco, M. The synthesis of antimicrobial peptides in the skin of Rana esculenta is stimulated by microorganisms, FASEB J. 2001; 15:1431-1432.
[8] Simmaco M., Mignogna G., Canofeni S., Miele R., Mangoni M.L., Barra D. Temporins, antimicrobial peptides from the European red frog Rana temporaria. Eur. J. Biochem. 1996; 242:788-792.
[9] Conlon J.M., Kolodziejek J. and Nowotny N. Antimicrobial peptides from ranid frogs: taxonomic and phylogenetic markers and a potential source of new therapeutic agents. Biochim. Biophys. Acta 2004;1696: 1-14.
[10] Mangoni M.L., Papo N., Barra D., Simmaco M., Bozzi A., Di Giulio A., Rinaldi AC. Effects of the antimicrobial peptide temporin L on cell morphology, membrane permeability and viability of Escherichia coli. Biochem. J. 2004; 380:859-865.
[11] Mangoni, M. L., Saugar, J. M., Dellisanti, M., Barra, D., Simmaco, M., Rivas, L. Temporins, small antimicrobial peptides with leishmanicidal activity, J. Biol. Chem. 2005; 280:984-990.
[12] Mangoni M.L., Rinaldi A.C., Di Giulio A., Mignogna G., Bozzi A., Barra D. Simmaco M. Structure-function relationships of temporins, small antimicrobial peptides from amphibian skin. Eur. J. Biochem. 2000; 267: 1447-1454.
[13] Mignogna, G., Simmaco, M., Kreil, G., Barra, D. Antibacterial and haemolytic peptides containing D-alloisoleucine from the skin of Bombina variegata, EMBO J. 1993; 12: 4829-4832.
[14] Mangoni, M. L., Grovale, N., Giorgi, A., Mignogna, G., Simmaco, M., Barra, D. Structure-function relationships in bombinins H, antimicrobial peptides from Bombina skin secretions, Peptides 2000; 21: 1673-1679.
[15] Mangoni M.L., Papo N., Saugar J.M., Barra D., Shai Y., Simmaco M., Rivas R. Biochemistry. 2006; in pres
Eretici italiani del Novecento. Delio Cantimori negli studi di Luisa Mangoni
No full textProfilo della studiosa Luisa Mangoni attraverso gli studi e le pagine che ha dedicato a Cantimor
A Chemotaxonomical approach towards synthetic indicators of phytoplankton composition in the context of the Marine Strategy Framework Directive (MSFD).
No full textIn order to pursue the Good Environmental Status (GES) with the aim to reduce the negative effects of anthropogenic eutrophication, the MSFD includes several criteria to be followed, among which, for Descriptor 5 (Eutrophication), total chlorophyll concentrations and the shift in the diatom-to-flagellate ratio. Within this Descriptor, the assessment is based on the nutrient concentrations in the water column and their direct and indirect effect on Chl a concentration and species shift in floristic composition (e.g. diatom to flagellate ratio) used as indicators. However, the tools to reach the described criteria are not clearly defined neither agreed upon. In recent years, the chemotaxonomical approach to phytoplankton community composition is spreading. This is based on the observation that some pigments can be mainly attributed to specific algal classes and/or types and are therefore used as taxonomical markers (Wrigth S.W. and Jeffrey S.W., 2006, Mangoni O. et al., 2008). In some cases these can also be species-specific (Mangoni O. et al., 2011). This approach allows to map the main functional groups including smaller size groups usually underestimated by microscopical counts.
This works aims at analyzing the temporal dynamics of main phytoplankton groups along the water column at a fixed station in the Gulf of Naples from 2003 to 2010 as related to macro-nutrients and water column dynamics
La reazione delle olefine trisostituite con iodio e sali di argento. Nota V. Sintesi e proprietà dei 3-metil- e dei 2-metil-5α-colestan-2,3-dioli
No full textLa reazione delle olefine trisostituite con iodio e sali di argento. Nota V. Sintesi e proprietà dei 3-metil- e dei 2-metil-5α-colestan-2,3-dioli
No full text«Idee come fatti». Didattica e ricerca nelle lezioni sul fascismo di Luisa Mangoni
No full text«Ideas as Facts». Didactics and research in Luisa Mangoni’s lectures on Fascism\ud
The essay focuses on a course on Fascism, culture and Catholic Church held by Luisa Mangoni at Ca’ Foscari University of Venice in 1984/85 and attended by the author. It is aimed to provide an insight on the unique way to combine research experience and didactic methods which Mangoni practiced in her lectures, by identifying some of the topics she dealt with, and detecting their sources on her researches, published or still unpublished at the time (from L’Interventismo della cultura to Una crisi fine secolo, and beyond), alongside with fresh material and original comments delivered during classes. This characteristic combination allows to discern Mangoni’s own conception of the history of culture, intertwined as it was with a still unreleased profile of Italian fascism, whose features are suggested in the final paragraphs
Produzione Primaria
No full textIl metodo per la determinazione della produzione primaria fitoplanctonica consiste nell’incubare dei campioni di acqua di mare in due bottiglie chiare ed una scura in cui viene inoculata una quantità nota di soluzione radioattiva (NaH14CO3). Le due bottiglie chiare servono a mediare le eventuali differenze dovute alla non omogeneità del campione e danno, come risultato, la misura della produzione primaria. La bottiglia scura permette di stimare valori di 14C organico di “background” e l’eventuale fissazione di C che può avvenire al buio, principalmente per cause fisiche e chimiche.
Il metodo si basa sull’assunto che l’assimilazione del 14C-DIC è proporzionale a quella del 12C-DIC, tenendo conto di un fattore di correzione che compensi la differente velocità di assimilazione della 14C rispetto al 12C
The spatio-temporal dynamics of the size fractions and pigment spectra of phytoplankton assemblages in different coastal marine ecosystems.
No full textHost-defense peptides: from biology to therapeutic strategies
No full textPrimitive innate defense mechanisms in the form of gene-encoded antimicrobial peptides are now considered as potential candidates for the development of new therapeutics. They are well known for their function as the first protective barrier of all organisms against microbial infections. In addition, emerging studies reveal that they assist in modulating the host immune system. The biological properties of these host-defense peptides, their role in human health, their cell selectivity and related molecular mechanisms are discussed in this multi-author review along with the strategies to transform them or their peptidomimetics into clinically usable drug
Carrying capacity of pelagic ecosystems of the Ross Sea (Antarctica) during summer: primary production processes and limiting factors.
No full textThe Ross Sea is one of the most productive areas of the Southern Ocean; seasonal variations in biomass accumulation and production are very pronounced. Highest values of primary production are recorded in austral spring till early summer. During summer primary production sharply decreases and micro-nutrients limitation as well as deepening of the upper mixed layer have been invoked as major factors limiting phytoplankton growth. During austral summer 1996 and 2001 two oceanographic cruises were carried out in the Ross Sea within the framework of the PNRA.
Primary production processes are presented for different environmental conditions during austral summer characterized by ice free waters and extensive ice coverage in offshore waters.
In extensive pack ice coverage, the average Chlorophyll a (Chla) concentration was about three times the values recorded under ice-free conditions but the primary production was relatively lower. In situ primary production and photosynthetic parameters over few days show that in most of the area high primary production values occurs only in the first five meter of the water column and within the melting pack-ice. Notwithstanding the some values of phytoplankton biomass, water column stability, similar irradiance levels, photosynthetic capacity was suppressed in deeper layer indicating a low carrying capacity of pelagic ecosystem. In contrast to a very high variability in phytoplankton biomass and primary production, photosynthetic parameters vary within narrow ranges.
Spatial and temporal distribution of biomass (Chla), in situ simulated primary production, photosynthetic parameters (PvsE) are presented in order to assess the carrying capacity and limiting factors of primary production of the Ross Sea, during austral summer, in different environmental conditions
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