L'obiettivo di questa tesi di dottorato era lo studio della influenza di diversi amendanti organici sulla rizosfera e la costruzione di un modello matematico per descrivere il flusso di carbonio nella rizosfera. Per questo motivo, plantule di mais sono state seminate e cresciute all'interno di sistemi rhizobox. La frazione disponibile del carbonio in ogni strato è stata valutata con il biosensore luminescente P. Fluorescence 10586 PUCD607. Inoltre sono stati determinati il carbonio organico totale (TOC), la distribuzione degli acidi organici nella rizosfera e la carica microbica totale. Un modello matematico viene presentato che descrive il flusso del carbonio nella rizosfera. Il modello risolve un'equazione di diffusione-degradazione con lo schema di discretizzazione di Crank-Nikolson ed è accoppiato all'inverse modelling software pest. Infine viene proposto un modello concettuale per la descrizione della biodisponibilità delle sostanze nel suolo. / The main aim of this work was to study the effect of different organic amendments in the rhizosphere soil with innovative techniques, and the building of a modelling tool to describe the carbon flow in the rhizosphere soil. For this reason maize plants were grown in rhizobox systems amended with different organic materials. The available fraction of organic C in each layer was assessed with the lux-marked p. fluorescens 10586 pucd607. Total organic carbon (TOC), organic acid distribution in the rhizosphere and total number of culturable cells as colony forming units (CFU) were also determined. A modelling tool is presented that describes the carbon flow in the rhizosphere. The model solves with the Crank-Nicolson discretisation scheme a diffusion-degradation equation and is coupled to the inverse modelling software pest. Finally a five-compartment conceptual model is proposed for describing organic compounds bioavailabililty in soil.

L'ampia letteratura sul periodo di transizione delle bovine richiama sempre più ai rapporti negativi fra problemi di salute e performance delle bovine. Dimostrazioni sempre più numerose confermano l'instaurarsi, soprattutto nel primo mese di lattazione, di una condizione di “stress da malattia”, non sempre associata a manifestazioni cliniche, ma con le stesse conseguenze: i fenomeni infiammatori. I principali obiettivi dei nostri studi, sono stati quelli di meglio caratterizzare gli stati infiammatori puntando l'attenzione su due aspetti: 1°) le cause di variazione della risposta infiammatoria alla infezione microbica e i suoi rapporti con la produzione di latte, 2°) le conseguenze che i fenomeni infiammatori hanno a livello di ingestione degli alimenti, delle riserve corporee, della produzione quanti-qualitativa e quindi dell'efficienza alimentare. relativamente al primo aspetto, nelle bovine sottoposte ad analoga infezione si è osservata una risposta infiammatoria di intensità diversa e che pare in buona relazione con precedenti fenomeni infiammatori in atto o pregressi; inoltre la risposta più intensa ha portato ad un maggior calo produttivo. Le conseguenze sulla efficienza energetica sono state studiate comparando due gruppi di bovine caratterizzate da minori (Lo-lfi) o maggiori (UP-lfi) valori di un indice di funzionalità epatica (lfi). Da ciò è emerso che, nel primo mese di lattazione, specie dopo avvenuta correzione per l'energia mobilizzata delle riserve corporee, l'efficienza è minore nei soggetti con basso lfi per il probabile aumento dei costi del sistema immunitario, aumento che pare prolungarsi ben oltre il fenomeno infiammatorio. / The extensive literature on transition period of the cows suggests the growing frequency of negative relationship between health problems and performance. Many evidences confirm during the first month of lactation, the presence of a particular condition named “stress disease”, which is not always associated to clinical symptoms but has the same consequences: the inflammatory processes. The principal objective of this study was to better characterize the inflammatory processes with particular attention to: 1) cause of the changes in inflammatory response to a bacterial infection and its relationship with the milk production, 2) consequences of the inflammatory processes on feed intake, body reserves, quantity and quality of milk production and then on feed efficiency. relatively to the first, we have observed a different intensity of the inflammatory response (in bovine submitted at the same infection), and this response seems correlated to previous inflammatory processes, probably not resolved; moreover, the higher intensity in the inflammations response can be responsible of the milk production decline. The consequences on feed efficiency have been studied through the comparison between two groups of cows characterized by higher (up-lfi) or low (lo-lfi) values of the liver functionality index; from that was demonstrated that during the first month of lactation, the cows with low lfi had lower efficiency values, probably caused increased charge of the immunitary system and prolonged beyond the inflammatory status itself.

L'opinione pubblica percepisce fortemente il rischio derivante da sostanze chimiche sintetiche, ma ignora spesso quello derivante dalla presenza di sostanze tossiche naturali. Tra queste sostanze vengono classificate le micotossine; prodotti del metabolismo secondario di alcuni funghi. La maggior parte degli alimenti di origine vegetale e in particolare i cereali, possono andare incontro a contaminazione da parte di questi funghi, produttori di micotossine, in qualunque stadio. In particolare nel frumento le micotossine che si riscontrano più frequentemente sono l'ocratossina A (OTA) e il deossinivalenolo (DON), mentre nel mais, si riscontrano le Aflatossine e le fumonisine. Queste micotossine hanno effetti epatotossici, nefrotossici, mutageni e cancerogeni, è necessario perciò, un continuo monitoraggio della materia prima (frumento e mais), ma anche dei prodotti destinati all'alimentazione umana a base di questi cereali. / People experience deeply, the risk of synthetics chemicals substances, but often don't know the risk from naturals toxics substances. Between these substances, they are mycotoxins; fungi secondary metabolism's products. Most of vegetable food, as cereals, can suffer a mycotoxins contamination, for effect of these fungi, during any step of alimentary chain. In particular, in wheat , the mycotoxins more frequents are ochratoxin A end deossinivalenol, while in the maize can find aflatoxins and fumonisins. These mycotoxins can have hepatotoxics, nefrotoxics, mutagens and cancerogens effects. This study has monitored contamination's levels of raw material (wheat and maize), but also of foodstuff containing cereals.

In questa tesi di dottorato sono stati indagati i punti critici del ciclo vitale del fungo Fusarium verticillioides, produttore di fumonisine in mais. Le fumonisine sono metaboliti secondari prodotte da funghi appartenenti tutti al genere fusarium e sono state classificate come sostanze cancerogene per l'uomo e per gli animali. Gli argomenti trattati nei vari capitoli sono stati: contaminazione da fumonisine nel mais coltivato nel nord Italia ed effetto delle diverse tecniche colturali, produzione di spore, dispersione di spore, infezione, parametri ecologici che condizionano la crescita e l'accumulo di fumonisina ed il controllo con mezzi chimici in campo su F. verticillioides e Ostrinia nubilalis, un lepidottero che aumenta la contaminazione. / Aim of this work was to collect missing information about critical point of the disease life cycle, to develop a conceptual model for the dynamic simulation of the life cycle of Fusarium verticillioides in maize and the consequent production of fumonisin B1 in kernels. Fumonisin is a secondary metabolite reported as toxigenic in humans and animals. Issues treated are: Fumonisin contamination in maize in Italy and effect of field managements, spore production, spore dispersal, variables influencing growth and toxin accumulation and chemical control of the disease in field.

Per varie ragioni, tra cui le loro specifiche condizioni di crescita, la diagnosi di infezione e di contaminazione alimentare da clostridi presenta ancora numerose difficoltà sia a livello clinico-batteriologico che a livello molecolare. In questo lavoro di tesi si è cercato di ampliare lo spettro di conoscenze riguardo i clostridi e la loro diffusione; durante il primo anno di ricerca è stato studiato, applicando nuove tecniche di microscopia, il processo di germinazione di Clostridium tyrobutyricum, uno dei batteri maggiormente responsabili del gonfiore tardivo dei formaggi a pasta dura; l’applicazione di tecniche di Real-Time PCR ha nel contempo reso possibile una determinazione quantitativa dello stesso in latte. Successivamente, è stata condotta un’analisi di tipizzazione molecolare di clostridi nell’ambito di una filiera agro-zoo-casearia finalizzata alle matrici di processo al fine di individuare le possibili vie di diffusione dei microrganismi. La parte finale del lavoro è stata dedicata allo studio di espressione genica di un altro Clostridium responsabile di gonfiore ma scelto perché geneticamente indistinguibile da Clostridium botulinum, ovvero il Clostridium sporogenes; l’analisi trascrizionale dei suoi geni durante le fasi vegetativa, di sporulazione, germinazione ed esocrescita ha permesso di assegnare diverse funzioni a geni singoli o a gruppi di geni allo scopo di utilizzare queste informazioni per formulare ipotesi future anche su altre specie di clostridi patogeni. / For several reasons, including their specific growth requirements, the diagnosis of infections and food contamination caused by clostridia still presents much difficulty at the clinical, bacteriological and molecular levels. The main purpose of this work is to learn more about clostridia and their interactions with environment. First, new microscopy techniques have been used to study the germination process in Clostridium tyrobutyricum, an anaerobic bacterium responsible for late blowing defects during cheese ripening; meanwhile, the application of real-time PCR methods have been employed to enumerate C. tyrobutyricum cells and spores in milk. Then, a molecular genotyping has been set in order to identify the most common clostridia in a agro-dairy production aimed to detect the possible ways of diffusion of these microbial species. The last part concerns the study of expression patterns of Clostridium sporogenes, an apathogenic gram positive clostridium usually involved in food damage and frequently isolated from late bowled cheese; Clostridium sporogenes is genetically indistinguishable from Clostridium botulinum and is often used as a model for the toxic subtypes. The objective of this study is to use an array-based large-scale transcriptional analysis in order to study gene expression in four different steps of Clostridium sporogenes life cycle: vegetative cells, sporulating cells, dormant spores and germinating ones. Our aims includes being able to relate gene-expression patterns to specific phenotypes and to discover gene expression divergences between the different phases of living, germination and outgrowth of spore-forming bacteria. An important aim is to assign functions to groups of or individual C. sporogenes genes and use this information to formulate specific hypotheses for further testing also on pathogenic clostridia types.

Brachypodium distachyon è stato recentemente proposto come pianta modello per le Triticeae che includono frumento e orzo. L’obbiettivo del presente studio è stato quello di identificare regioni genomiche associate con la resistenza quantitativa alla ruggine fogliare in Brachypodium. Le malattie causate dalle ruggini fogliari causano ingenti perdite in termini di produzione delle specie cerealicole. Una popolazione di 110 individui F2 è stata sviluppata incrociando due linee inbred di Brachypodium e una mappa di linkage di marcatori AFLP è stata create. La mappa di linkage consiste di 192 loci AFLP in dieci gruppi di linkage, e copre una lunghezza pari a 1,231 Kosambi cM. Allo scopo di identificare loci coinvolti nella resistenza quantitativa sulla mappa, i 110 individui F2 sono stati valutati per la loro reazione alla ruggine fogliare allo stadio di plantula e a quello adulto. Per confermare i risultati delle piante F2, le rispettive famiglie F3 sono state studiate per la loro resistenza alla ruggine fogliare in due esperimenti indipendenti. Due loci genomici sembrano essere maggiormente coinvolti nella resistenza. / Brachypodium distachyon has been proposed as a model species for the tribe of the Triticeae, which includes wheat and barley. The objective of our study was to identify the genomic regions associated with quantitative resistance to leaf rust in Brachypodium. Leaf rust diseases cause significant reductions annually in yield of cereal crops worldwide. An F2 mapping population of 110 individuals was generated between two Brachypodium inbred lines and a AFLP-based linkage map was developed. The linkage map consists of 192 AFLP loci in ten linkage groups, and spans a total genetic length of 1,231 Kosambi cM. To locate quantitative resistance loci on the map, the 110 F2 plants were evaluated for their reaction to the leaf rust at both seedling and adult plant stages. To improve QTL identification, F2-derived F3 families were studied for resistance to leaf rust in two independent experiments. Two major genomic regions involved in resistance to leaf rust were detected.

La peronospora della vite è causata dall’Oomicete eterotallico Plasmopara viticola ed è ampiamente diffusa in tutte le aree caratterizzate da primavere miti e piovose. Gli organi svernanti di questo patogeno sono le oospore, che rappresentano l’unica fonte di inoculo per le infezioni primarie. Recenti studi molecolari hanno evidenziato l’importanza delle infezioni primarie e suggerito una revisione dell’epidemiologia di P. viticola. Questa tesi è costituita dagli studi epidemiologici realizzati per indagare il processo di maturazione e germinazione delle oospore mirati all’elaborazione di un modello dinamico per la simulazione delle infezioni primarie di P. viticola. Il modello è stato successivamente validato in diverse aree viticole italiane e, inoltre, utilizzato come base per un warning system in tempo reale per la gestione dei trattamenti in vigneto. / The heterothallic Oomycete Plasmopara viticola represents the causal agent of downy mildew of grapevine (Vitis spp.). The unique source of inoculum is represented by the overwintering sexual spores, originated by the fusion between anteridium and oogonium, so called oospores. Despite their critical impact on the epidemiology of this disease, knowledge about oospores presents some inconsistencies that are engaged in the present dissertation. Initially, the effect of water moistening the grape leaf litter holding overwintering P. viticola oospores was investigated. A close relationship was found between vapour pressure deficit (VPD in hPa) and aW (water activity) of the leaf litter, so that when VPD is lower than 2.13 hPa there is sufficient water for oospores to develop. Results showed that moisture of the leaf litter due to the water flow from the atmosphere makes the oospore development possible also during non rainy periods. Then, the effects of environmental conditions on the variability in germination dynamics of Plasmopara viticola oospores were studied over five years. The germination course was determined indirectly as the relative infection incidence (RII) occurring on grape leaf discs kept in contact with oospores sampled from a vineyard between March and July. The time elapsed between the 1st of January and the infection occurrence was expressed as physiological time, using sums of hourly rates from a temperature-dependent function only in hours when VPD was not a limiting factor (hydro-thermal time, HT). The Gompertz equation calculated over hydro-thermal time produced a consistent modelling of the general relationships between the germination dynamics of a population of P. viticola oospores and weather conditions. It represents the relative density of the seasonal oospores that should have produced sporangia when they have experienced favourable conditions for germination. Finally, a dynamic model for Plasmopara viticola primary infections on grapevine was elaborated according to a mechanistic approach. Development of the sexual stage of the pathogen was split into different state variables, in which changes from one state to another were regulated by rates depending on environmental conditions. The conceptual model was based on the definition of a primary inoculum season, a seasonal oospore (inoculum) dose, and its division into many coeval cohorts. Each cohort progresses along the primary infection cycle (production and survival of sporangia, release, survival and dispersal of zoospores, infection, appearance of disease symptoms) simultaneously, with a time step of one hour. The model was evaluated by comparing model predictions with disease onset in: i) 100 vineyards of Northern, Southern and Insular Italy (1995 to 2007); ii) 42 groups of potted grapevine plants exposed to inoculum (2006 to 2008). Most of the wrong positive predictions occurred in early season, when the host was in the earlier growth stages, or when the oospore germination was triggered by isolated weak rain events. Considering that neither calibration nor empirical adjustment of model parameters were necessary to obtain accurate simulation, it was concluded that this model produces a reasonable approximation of the primary infection processes underlying oospore development. A warning system based on such a model and on short-term weather forecasts was developed and its use was evaluated in experimental vineyards over a 3-year period in North Italy. An unsprayed control was compared with a “warning” treatment (fungicides were applied when the warning system predicted an infection), a “threshold” treatment (fungicides were applied as in the warning treatment, but only for the oospore cohorts higher than a fixed threshold), and the grower’s schedule. Average efficacy in decreasing disease incidence on leaves compared to the unsprayed control was > 90% for all treatments. On the average, 6.8 sprays were applied following the grower’s schedule; use of the warning system reduced applications by about one half (warning treatment) or two third (threshold treatment). The grower’s schedule was the most expensive control strategy, with average of 337 €/ha; the average saving was 174 and 224 €/ha for the warning and the threshold treatments, respectively. The value of this dissertation consists in two relevant and connected aspects. From one side the studies performed on the oospore maturation and germination allowed to better understand and clarify a key point of the downy mildew epidemics still wrapped by a lack of information. From the other side the model elaborated during this thesis represents a practical and efficient tool that leads to the reduction both of growers’ costs and chemical input in the environment.

I cambiamenti previsti nel clima delle regioni europee viticole nei prossimi decenni potrebbero alterare significativamente la distribuzione dei vitigni attualmente in uso. A seguito della problematica di cambio climatico, e degli effetti che possono essere indotti sull’intero comparto vitivinicolo, il lavoro di tesi ha riguardato essenzialmente la possibilità di applicare in modo innovativo tecniche colturali già esistenti, o di nuova ideazione, all’ecosistema viticolo per minimizzare gli effetti da riscaldamento globale e rendere se possibile, più sostenibile il vigneto del futuro. / The expected changes in the climate of European winegrowing regions over the next decades may significantly alter both the spectrum and distribution of the varieties currently in use. Following the issue of climate change, and the effects that can be induced on the entire wine industry, the thesis work focused in particular on the possibility of applying an innovative growing techniques already existing or newly developed, to the viticultural ecosystem in order to minimize the effects of global warming and make, if possible, more sustainable the future of viticulture.

The research made in the current master thesis uses theoretical framework from the area of project management, voluntary labor turnover and performance appraisal. Prior research based on existing literary sources allows assuming that the following factors, such as job alternatives, knowledge intensity and nature of work have specific relevance for the emergence of voluntary labor turnover in project-based organizations. Employees of the case study company-AGR Field Operations´ Maintenance Engineering department were interviewed and surveyed in order to determine the relevance of those factors on the example of a concrete project-based organization. The obtained results indicate that the nature of work is more significantly related to the emergence of the voluntary labor turnover in the given case study department. Whereas availability of more job alternatives due to being close to the client or knowledge intensity factor of becoming more generalist do not have the same influence. During the course of the research it was discovered that the department uses outcome-based type of performance appraisal which is proved to be unsuitable in the given organizational settings. To that matter there were provided further suggestions in the field of performance appraisal. The current research will attempt to identify specific factors contributing to the emergence of the voluntary labor turnover specifically for project-based organizations. As well as it will attempt to give suggestions for improvement of the concrete case study department´s performance appraisal tools and thus supplement turnover reduction actions already put in place by the department management.

Questa tesi descrive lo stato delle conoscenze degli effetti tossici da micotossine su animali d allevamento, ed alcuni esperimenti condotti per valutare gli effetti indotti da esposizione cronica da micotossine sui ruminanti. Uno studio è stato condotto su 15 aziende specializzate in sistemi di produzione intensiva di carni bovine, situate nel Nord Italia (province di Verona e Mantova), con l'obiettivo di individuare i rischi d esposizione a contaminazione da micotossine. Alcuni metodi di laboratorio sono stati sviluppati: un metodo per la determinazione di ocratossina A (OTA) accumulata in tessuti e organi; Un metodo per valutare gli effetti delle fumonisine sulla biosintesi delle basi sfingoidi sfingosina (So) e sfinganina (Sa); Un metodo per rilevare l addotto AFB1-albumina. La razione totale mescolata (TMR) è risultata positiva alla AF e FB. Tra i singoli alimenti, il mais e la semola glutinata di mais sono stati i principali responsabili della contaminazione del TMR. Il livello di contaminazione è positivamente correlato al contenuto di umidità di mais. Il metodo per la determinazione dell OTA nei tessuti ed organi ha mostrato un buon recupero medio. L'analisi del rapporto Sa/So nel sangue non ha mostrato alcun effetto negativo delle fumonisine sulla biosintesi lipidica. L'addotto AFB1-albumina è risultato positivo per il 18% dei campioni totali di sangue. / The thesis describes the state of knowledge about toxic effects of mycotoxins on farm animals, and some experiments conducted to assess effects induced by chronic exposure to mycotoxins on ruminants. A field study for was carried out on 15 farms specialised for intensive beef production system, located in Northern Italy (provinces of Verona and Mantova), with the aim to identify risks of exposure to mycotoxins contamination. Some laboratory methods were performed: a method for the detection of ochratoxin A (OTA) concentration in tissues and organs; a method for evaluating the effects of fumonisin on biosynthesis of the two sphingoid bases sfingosine (So) and sphinganine (Sa); a method to detect the AFB1-albumin adduct. Total mixed rations (TMR) resulted positive for AF and FB contamination. Among single feedstuffs, corn and corn gluten feed were the main responsible for TMR contamination. Level of contamination was positively related to corn moisture content. The method for the determination of OTA in tissue and organ showed a good mean recovery. The analysis of ration Sa/So in blood did not show any negative effect by fumonisin on the lipidic biosynthesis. The AFB1-albumin adduct was positive on 18% of total blood samples.