702 research outputs found
Sort by
Analisi dei dati di consumo e del flusso informativo dei farmaci rendicontati tramite File F nell’ambito dei rimborsi della spesa farmaceutica: il modello applicato all’Azienda Ospedaliera di Varese.
No full textins ricorda che il dottorato sarebbe in farmacologia e farmacoepidemiologi
Rootarchitecture in woody species: the formation of new lateral emissions from root secondary structures.
No full textmissin
Sustainable management of hydraulic diversions in fluvial ecosystem.
No full textThis thesis focuses on the study of the negative effects induced on stream ecosystems by hydropower schemes in an Alpine river system. The downstream ecological consequences of 4 controlled free-flow flushing operations designed to remove sediments accumulated in an Alpine reservoir are described. Sediment removals were carried out for analogous duration and in the same period of the year from 2006 to 2009. Brown trout populations were remarkably reduced after the beginning of flushing operations, but appeared to reach equilibrium with the new environmental conditions. Macroinvertebrate fauna, despite exhibiting a significant reduction in abundance and biomass following each flushing, showed a quick recovery within 3 months. Nevertheless, the yearly occurrence of sediment flushing changed the taxa composition, allowing species with fast life cycle and good colonizing ability to become dominant. Particle size analysis of core samples collected in riffle habitats provide evidence of a significant increase in interstitial fine sediment, that could adversely affect the recovery processes. Maximum allowable SSCs of 10 g L-1(daily average) and 5 g L-1(overall average) for flushing operations carried out in small to medium high-gradient Alpine streams are recommend. In the same river network, a data set (n=30) of free-flowing and altered flow streams was used to detect the effects of water diversion on macroinvertebrate communities using single and multimetric indices as well multivariate approaches. Although macroinvertebrate diversity decreased significantly in response to reduced flows, the results suggest that invertebrate-based metrics may be poor descriptors of the magnitude of flow reduction. A consistent pattern in the dataset was demonstrated through multivariate analysis by groups of taxa that were respectively reduced or increased in abundance at the impaired sites, confirming that diversions are potentially responsible for a change in macroinvertebrate composition.
The findings of this research showed how both activities have the potential to alter biological communities, but even that could be managed together to minimize risks. Considering obtained results this project will help support current and future research of Alpine stream ecosystems and will provide information for a management of freshwater resource balancing economical, technical and environmental issues
Obbligo politico e libertà. Francisco Suárez: precursore del giusnaturalismo moderno.
No full textmissin
Molecular cloning and expression analysis of genes involved in the compensatory growth of sea bass (Dicentrarchus labrax).
No full textIn natural aquatic systems, many fish species experience periods of fasting during their life cycle because of the high variation in food availability. Although fish are highly tolerant to relatively long periods of food deprivation, energy storage and growth rate is reduced in those that experience different degrees of starvation, redirecting this energy towards maintenance metabolism. Fasting-associated growth retardation is completely overcome, or at least reduced, if an abundant food supply becomes available after a prolonged period of food shortage. Then, fish display an exceptionally rapid growth rate known as “compensatory growth”.
There are several descriptions of compensatory growth in fishes, but the mechanisms involved in such rapid recovery from fasting are still not fully understood. Such mechanisms have principally been searched for at the level of total fish growth where a number of circulating hormones are thought to be involved. Some attention has also been paid to muscle growth and to locally produced paracrine/autocrine factors, which can profoundly affect tissue growth and development. Only little information is available at the molecular level.
Accordingly, this research focused on identifying candidate genes whose expression contributes to the compensatory growth induced by refeeding in sea bass (Dicentrarchus labrax), a marine fish of great interest for Mediterranean aquaculture. In the course of the study, we firstly isolated the complete cDNAs encoding diverse physiologically relevant proteins involved in lipid and protein metabolism, and then assessed the impact of chronic feed deprivation and subsequent refeeding on their mRNA abundance levels in different tissues, with the aim to relate these expression levels to fish feeding status.
The molecular cloning and sequencing strategy resulted in the isolation of cDNAs that encode the following proteins:
- Δ6 desaturase, which has a recognized capacity to desaturate the fatty acids with 18 carbon atoms, into highly unsaturated fatty acids (HUFA) with 20 and 22 carbon atoms.
- Lipin, an enzyme required for triacylglycerol and phospholipid biosynthesis, and a transcriptional coactivator in regulating lipid metabolism genes.
- Peroxisome proliferator-activated receptor (PPARγ), a central factor in the control of the expression of genes involved in lipid homeostasis.
- Oligopeptide transporter (PepT1), an integral plasma membrane protein responsible for the uptake of dietary di- and tri-peptides from the intestinal lumen into the enterocytes.
The isolated sequences were then deposited in GenBank databases with the following accession numbers: EU647692 for Δ6 desaturase; EU644089 for lipin; FJ237043 for PepT1. The evolutionary relationship of all target genes with respect to other publicly available related genes in other teleosts, amphibian, avian, and mammalian species, was also studied.
After the sequence isolation, for the quantification by real-time RT-PCR of each gene transcript levels, in response to the nutritional status of the animals, a fasting and refeeding trial was conducted at the marine water recirculating system at our department in Varese. Briefly, 140 sea bass were stocked into four tanks of 2 m3
each, with 35 fish per tank. At the start of the experiment, all the fish were weighed, and two of the tanks were randomly assigned to each of two treatments.
Fish in these two tanks were fed to apparent satiety (control), whereas fish in the other two tanks were deprived of food for 35 days and then refed to apparent
satiety for 21 days with the same type of feed utilized before fasting. Five fish from each of the experimental groups were sampled at the following time points: before fasting (day 0), 4 days after fasting, at the end of fasting, and then sequentially at 4, 14, and 21 days following refeeding. For the molecular biology analysis, the whole digestive tract, liver, gill, heart, kidney, ovary, brain, muscle and spleen were dissected out.
After 35 days of fasting body weight of fasted fish were lower than the fed controls, whereas during the subsequent refeeding period, previously unfed fish were able to increase body weight sufficiently to overcome weight loss imposed by the 35 days feed restriction. This is the evidence that the compensatory growth was in play.
The results of the real-time RT-PCR absolute quantification using the mRNA standard curve method, revealed that the nutritional status significantly influenced E6 desaturase, lipin and PPARγ mRNA copy number in the liver of sea bass, inducing an up-regulation during prolonged fasting (35 days) and a downregulation during the recovery from fasting (21 days of refeeding).
In the proximal intestine, 35 days of fasting contributed to a significant decrease in E6 desaturase transcript levels, whereas the subsequent recovery from fasting was associated with an increase in E6 desaturase mRNA copy number, which return to normal (control) levels after 21 days of refeeding.
The abundance of lipin and PPARγ mRNA levels in the proximal intestine were not affected by the availability of food, as they remained similar between fed, fasted and refed fish.
The nutritional status significantly influenced PepT1 mRNA copy number in the proximal intestine of sea bass, inducing a down-regulation during 35 days of fasting and an up-regulation during the subsequent 21 days of refeeding. This pattern of expression seems to be in complete support of the compensatory growth. The increase in the transcripts of the intestinal oligopeptide transporter Pept1 might be correlated to the great quantity of protein taken in with the food in the initial days of refeeding. In fact, refeeding of sea bass after a long starvation period was marked by hyperphagia, as early as the first day.
In conclusion, we have isolated the cDNA sequences encoding Δ6 desaturase, lipin, PPARγ and Pept1in sea bass, and also demonstrated that the nutritional state of the animal influences their levels of expression. The present study is the first one to investigate the behavior of these transcripts over a long period of fasting and subsequent refeeding of fish. We recognize that mRNA levels in our study do not measure physiological effects produced by the proteins. Due to this, our hypothesis that the aforementioned genes are important triggers of the fasting response in the sea bass, will have to be confirmed by future studies
Development and application of a marine biotic index for the evaluation of the influence of aquaculture activities on the benthic ecosystem in Mediterranean coastal areas.
No full textThe project was oriented to the development of an innovative tool for a more complete evaluation of the effect of marine aquaculture on the benthic ecosystem. Due to their high sensitivity, the attention was focused on the macroinvertebrates communities and on their use as descriptor of the marine soft bottom “health status”. Therefore, the AMBI, an existing marine biotic index already applied to detect impacts along European Coasts but never for the evaluation of the effects of aquaculture in the Mediterranean Sea, was developed and tested in four cases study: two off-shore fish farms, one in Sardinia and another one in Cyprus and two land-based fish farms in Tuscany. Assigning the macrobenthic species to one of the five Ecological Groups defined by this index, related to species sensitivity to disturbance, the AMBI gives back a classification of the site based on the benthic community “health status”. Thus, for each fish farm, samples of sediment were collected and chemical (total nitrogen, total carbon, organic matter, water content), physical (granulometry) and biological analysis (quantitative and qualitative indices calculation) were carried out. Concerning the biological analysis, all the organisms collected were counted and identified to the lowest possible taxon. The obtained data were used to calculate biological indices, including AMBI. For each case study, new species were added to the AMBI database, and this allowed the correct calculation of the index. The obtained results underlined the potentiality of AMBI in detecting effects of aquaculture on the benthic ecosystem and the development of this index database extended the possibility to use it also for the Mediterranean Sea
Il Terzo Regno: la recezione di Gioacchino da Fiore nella filosofia politica del 1900.
No full textmissim
Biodiversity in eastern Mediterranean marine aquaculture: an approach to new species.
No full textAquaculture is an important agro-food activity to ensure the amount of EPA and DHA indicated by WOS for human health, on the top of precious proteins. In spite that in the Mediterranean area only few marine species (sea bass and sea bream) cover the 92.4% of the market, an increased biodiversity in the production would improve the nutritional quality, as well as the resource for the market and the possibility to better exploit natural resources. This research work is focused on the evaluation of biological and physiological functions of new species, such as rabbitfish (Siganus rivulatus) and common pandora (Pagellus erythrinus),
in respect to their capacity for aquaculture production. Morphometric measurements on wild rabbitfish revealed that the TL-TW relationship is described by the equation y=0.068x+11.044. Condition factor (K) was 1.65±0.17, HSI was 1.4±0.4 and GSI was found to reach maximum values near the full moon during summer months. Respirometry on individual cultured rabbitfish was measured at 17, 20, 23 and 26°C.
Oxygen consumption rate increased with water temperature and it was varied between 2.4×10-3 mg O2/g BW/min at 17°C and 1.1×10-2 mg O2/g BW/min at 26°C. Hypoxia-inducible factor-1a, which responds to changes in available oxygen in the cellular environment, was identified in brain and liver samples. Growth experiment on rabbitfish that lasted for 1 year and tested two feeds with different protein content, 35 and 44%, showed no significant difference between the two treatments. Experiment on the effect of vitamin C and astaxanthin on the reproduction performance and quality of eggs and larvae in common pandora, showed that vitamin C improves the reproductive capacity of broodstock and the quality of offsprings
Predisposizione e valutazione critica di scenari di esposizione in ambito REACh: sostanze ad attività disendocrina (Ftalati).
No full textThe new REACH legislation formally introduces the control and development of exposure scenarios for substances deemed capable of altering the hormonal system. Example of compounds that alter the endocrine system (endocrine disruptors) and subject of this thesis are the phthalates.
Phthalates are organic chemicals derived by esterification of phthalic anhydride. They are used to make soft and flexible a variety of products, including toys. These articles are used by children, most likely subpopulation.
The main objective of the project is to conduct a risk assessment for these substances. The first phase of the evaluation was to determine the toxic properties of these substances (by literature search), after that, taking into account the most likely population, we have been developed hypothetical scenarios of exposure (using the software ConsExpo) for 3 classes: Babies (4.5 months), newborn (7.5 months), children (13.5 months).
Finally, to perform the risk characterization, was made in connection the dangers of these substances with the exposure and was rated the likelihood or occurrence of adverse effects on children.
The results obtained from the risk assessment (using as a method the Margin of Safety), lead to the conclusion that there is a negligible risk in the use of toys containing phthalates even if concentration was above legal limits (DEHP: 43.3%, and DINP: 49.9%).
Although the results are encouraging, in the future will need to conduct further analysis and risk assessment for phthalates, taking into account the cumulative effect of the different phthalates and the effect of phthalates and other substances with the same mechanism of action or the same target organs