Search results for "biologic"
showing 4 items of 12804 documents
Long-term changes in pigmentation of arctic Daphnia provide potential for reconstructing aquatic UV exposure
2016
Abstract Despite the biologically damaging impacts of solar ultraviolet radiation (UV) in nature, little is known about its natural variability, forcing mechanisms, and long-term effects on ecosystems and organisms. Arctic zooplankton, for example the aquatic keystone genus Daphnia (Crustacea, Cladocera) responds to biologically damaging UV by utilizing photoprotective strategies, including pigmentation. We examined the preservation and content of UV-screening pigments in fossil Daphnia remains (ephippia) in two arctic lake sediment cores from Cornwallis Island (Lake R1), Canada, and Spitsbergen (Lake Fugledammen), Svalbard. The aims were to document changes in the degree of UV-protective p…
Phosphorus limitation enhances parasite impact: feedback effects at the population level
2014
Background Nutrient deficiency affects the growth and population dynamics of consumers. Endoparasites can be seen as consumers that drain carbon (C) or energy from their host while simultaneously competing for limiting resources such as phosphorus (P). Depending on the relative demands of the host and the parasite for the limiting nutrient, intensified resource competition under nutrient limitation can either reduce the parasite’s effect on the host or further reduce the fitness of the nutrient-limited host. So far, knowledge of how nutrient limitation affects parasite performance at the host population level and how this affects the host populations is limited. Results We followed the popu…
ATTIVITÁ DI RICERCA PER LO SVILUPPO DELLA ZOOTECNIA BIOLOGICA IN SICILIA
2008
Con l’intento di contribuire allo sviluppo del settore zootecnico biologico, gli autori hanno realizzato, attività di ricerca rivolte: - allo studio della possibilità di inserire, nella razione alimentare delle bovine e delle pecore in lattazione, fonti alternative al mais e alla soia, con la finalità di superare il problema degli OGM e di ridurre il rischio di contaminazione degli alimenti con micotossine; - alla valutazione degli effetti del carico animale al pascolo, finalizzato ad una maggiore efficienza produttiva dei sistemi pascolivi destinati agli ovini; - alla individuazione dei riflessi della dieta, variabile in funzione del concentrato utilizzato e del carico al pascolo, sulla qu…
Chemical composition and biological activity of the essential oil of Ballota hispanica (L.) Benth. growing wild in Sicily
2015
Ballota L. comprises several relevant species largely used for their excellent therapeutic properties. Ballota hispanica (L.) Benth. is widely used in herbal medicine, and it is sold in herbalist shops for its sedative and antispasmodic properties. Considering its traditional medicinal use and the lack of scientific studies on the volatile components of this species as well as on its biological activities, in this study the chemical composition of the essential oil from aerial parts of B. hispanica, collected in Sicily, was evaluated by gas chromatography and gas chromatographyâmass spectrometry. α-Elemol was the most abundant component of the oil (10.9%), followed by α-ylangene (8.5%),…