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Heterosis in maize (Zea mays, L.): characterization of heterotic quantitative trait loci (QTL) for agronomic traits in near isogenic lines (NILs) and their testcrossesCané, Maria Angela <1978> 06 June 2011 (has links)
In a previous study on maize (Zea mays, L.) several quantitative trait loci (QTL) showing high dominance-additive ratio for agronomic traits were identified in a population of recombinant inbred lines derived from B73 × H99. For four of these mapped QTL, namely 3.05, 4.10, 7.03 and 10.03 according to their chromosome and bin position, families of near-isogenic lines (NILs) were developed, i.e., couples of homozygous lines nearly identical except for the QTL region that is homozygote either for the allele provided by B73 or by H99. For two of these QTL (3.05 and 4.10) the NILs families were produced in two different genetic backgrounds. The present research was conducted in order to: (i) characterize these QTL by estimating additive and dominance effects; (ii) investigate if these effects can be affected by genetic background, inbreeding level and environmental growing conditions (low vs. high plant density). The six NILs’ families were tested across three years and in three Experiments at different inbreeding levels as NILs per se and their reciprocal crosses (Experiment 1), NILs crossed to related inbreds B73 and H99 (Experiment 2) and NILs crossed to four unrelated inbreds (Experiment 3). Experiment 2 was conducted at two plant densities (4.5 and 9.0 plants m-2). Results of Experiments 1 and 2 confirmed previous findings as to QTL effects, with dominance-additive ratio superior to 1 for several traits, especially for grain yield per plant and its component traits; as a tendency, dominance effects were more pronounced in Experiment 1. The QTL effects were also confirmed in Experiment 3. The interactions involving QTL effects, families and plant density were generally negligible, suggesting a certain stability of the QTL. Results emphasize the importance of dominance effects for these QTL, suggesting that they might deserve further studies, using NILs’ families and their crosses as base materials.
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Studio di caratteri correlati a stress idrico in una collezione di cultivar di frumento duro (Triticum durum Desf.) / Investigation on water-stress related traits in a collection of Durum wheat (Triticum durum Desf.) cultivarsFrancia, Rossella <1978> 10 June 2013 (has links)
L’agricoltura si trova ad affrontare una diminuzione della disponibilità d’acqua ed una crescente domanda della produzione di cereali per scopi alimentari. Sono perciò necessarie strategie di coltivazione innovative per migliorare la produttività e nuovi genotipi migliorati nell'efficienza dell’uso delle risorse in condizioni di siccità. Questi rappresentano gli obietti principali del progetto “DROPS” (Drought tolerant yielding Plants) all’interno del quale ha avuto luogo il mio progetto di Dottorato.
La mia attività di ricerca è stata svolta come segue:
1. Caratterizzazione molecolare di un panel di188 accessioni di frumento duro con marcatori SSR e DaRT;
2. Esperimenti in serra su 100 accessioni del panel per valutare la Water-Use Efficiency (WUE) in sei repliche secondo un Alpha Lattice design;
3. Prove sul campo, effettuate secondo un Alpha Lattice design, in due stagioni di crescita:
a. 2010/11, valutazione di 100 accessioni presso l’Azienda sperimentale dell'Università di Cadriano (BO);
b. 2011/12, valutazione del panel completo in 3 ambienti, con due diversi regimi irrigui
In entrambi gli anni, abbiamo valutato caratteri agronomici correlati con il ciclo di sviluppo, la resa di granella e sue componenti, nonché diversi fattori ambientali e del suolo. Per quanto riguarda WUE, abbiamo trovato differenze altamente significative tra accessioni; inoltre, cinque accessioni hanno mostrato elevati valori di WUE e cinque accessioni valori molto bassi di WUE in tutte e sei le repliche. Gli esperimenti di campo nelle stagioni 2011 e 2012 hanno evidenziato differenze altamente significative tra le accessioni del panel per la maggior parte dei caratteri analizzati, confermando inoltre che il panel di fiorisce entro una settimana. L'esperimento del secondo anno ci ha permesso osservare un significativa interazione Genotipo X Ambiente. Questi risultati saranno integrati con ulteriori analisi QTL, per identificare regioni cromosomiche coinvolte nel controllo genetico dei caratteri di interesse e verificare la stabilità dei QTL in diversi ambienti. / Agriculture is facing a decline in water availability and an increasing food demand. Novel crop strategies are needed to improve yield and resource-use efficiency in water-limited conditions. Contributing to the development of such new strategies is the main aim of the European project DROPS (DROught- tolerant yielding PlantS), in which my PhD project took place.
For my study, the main plant material was a panel of 188 durum wheat cultivars.
My research activity included:
1. Molecular characterization of 188 durum wheat accessions with SSR and DaRT markers;
2. Glasshouse experiments involving 100 accessions of the panel which were evaluated for Water-Use -Efficiency accordingly to an Alpha Lattice design;
3. Field trials, performed accordingly to an Alpha Lattice design, in two growing seasons:
a. 2010/11; evaluation of 100 durum wheat accessions at the University experimental station in Cadriano (BO);
b. 2011/12; evaluation of 188 durum wheat accessions in 3 environments, with two different water treatments.
In both years, we measured plant traits related with developmental cycle, grain yield and its components, as well as a number of environmental and soil characteristics.
Concerning Water-Use-Efficiency, we found highly significant differences between genotypes within the panel. In all the replicates, five accessions showed higher WUE and five lower WUE as compared to the rest of the 100 accessions under analysis. The first- and second- year field experiments evidenced highly significant differences between the lines in the panel for most of the investigated traits, and confirmed the property of the panel to flower within one week time.
The second-year experiment allowed us to first investigate the genotype by environment interaction. These results will be integrated with further QTL analysis, to identify chromosomal regions involved in the genetic control of traits of interest and to verify QTL stability across environments.
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Analysis of reciprocating single blade cutter barsMaglioni, Cesare <1977> 30 May 2007 (has links)
No description available.
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Effect of diet supplementation in unsaturated fatty acids on meat keeping qualities: study of selected fatty acids antimicrobial properties and inhibition mechanism on Staphylococcus aureusSado Kamdem, Sylvain Leroy <1973> 03 May 2007 (has links)
No description available.
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New signalling molecules in some foodborne bacteriaSaracino, Pasquale <1977> 03 May 2007 (has links)
No description available.
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"Zootecnia sostenibile": la produzione di uova con metodo biologicoScalabrin, Marilena <1977> 15 June 2007 (has links)
No description available.
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Utilizzo del virus del rachitismo cespuglioso del pomodoro (TBSV) come vettore virale per l’induzione di resistenza al virus della vaiolatura delle drupacee (PPV)Pignatta, Daniela <1979> 18 May 2007 (has links)
No description available.
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Studio dei meccanismi molecolari coinvolti nel determinismo sintomatologico di piante infette da virus e virus-satellitiContaldo, Nicoletta <1978> 06 June 2008 (has links)
The aim of our work was to study the molecular
mechanisms involved in symptoms appearance of plants
inoculated either with a virus or with a virus-satellite
complex.
In the first case, we tried to set up a reliable method for an
early identification of PVYNTN strains present in Italy and
causing potato tuber necrosis. This, to prevent their spread
in the field and to avoid severe yield losses, especially in
seed potato production. We tried to localize the particular
genomic region responsible for tuber necrosis. To this
purpose, we carried out RT-PCR experiments using various
primer combinations, covering PVY genomic regions larger
than those previously used by other authors. As the previous
researchers, though, we were not able to differentiate all
NTN from others PVY strains. This probably because of the
frequent virus variability, due to both genomic mutations
and possible recombination events among different strains.
In the second case, we studied the influence of Y-sat
(CaRNA5 satellite) on symptoms of CMV (Cucumber
mosaic virus) in Nicotiana benthamiana plants: strong
yellowing appearance instead of simple mosaic.
Wang et al (2004), inoculating the same infectious complex
on tobacco plants transformed with a viral suppressor of
plant silencing (HC-PRO), did not experience the
occurrence of yellowing anymore and, therefore,
hypotesized that changes in symptoms were due to plant
post transcriptional gene silencing (PTGS) mechanism. In
our case, inoculation of N. benthamiana plants transformed
with another PTGS viral suppressor (p19), and other plants
defective for RNA polymerase 6 (involved in systemic
silencing), still resulted in yellowing appearance. This, to
our opinion, suggests that in our system another possible
mechanism is involved.
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Attività antagonistica di batteri lattici isolati da salami verso muffe e lievitiCarri, Simone <1980> 13 June 2008 (has links)
No description available.
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Study of apoptotic deletion mediated by Bifidobacterium longum with construction of recombinant strains for Serpin encoding gene and phenotypes comparison in a pig cell modelNissen, Lorenzo <1977> 05 May 2008 (has links)
The first part of the research project of the Co-Advisorship Ph.D Thesis was aimed to
select the best Bifidobacterium longum strains suitable to set the basis of our study.
We were looking for strains with the abilities to colonize the intestinal mucosa and
with good adhesion capacities, so that we can test these strains to investigate their
ability to induce apoptosis in “damaged” intestinal cells. Adhesion and apoptosis are
the two process that we want to study to better understand the role of an adhesion
protein that we have previously identified and that have top scores homologies with
the recent serpin encoding gene identified in B. longum by Nestlè researchers.
Bifidobacterium longum is a probiotic, known for its beneficial effects to the human
gut and even for its immunomodulatory and antitumor activities. Recently, many
studies have stressed out the intimate relation between probiotic bacteria and the GIT
mucosa and their influence on human cellular homeostasis. We focused on the
apoptotic deletion of cancer cells induced by B. longum. This has been valued in
vitro, performing the incubation of three B.longum strains with enterocyte-like Caco-
2 cells, to evidence DNA fragmentation, a cornerstone of apoptosis. The three strains
tested were defined for their adhesion properties using adhesion and autoaggregation
assays. These features are considered necessary to select a probiotic strain. The three
strains named B12, B18 and B2990 resulted respectively: “strong adherent”,
“adherent” and “non adherent”. Then, bacteria were incubated with Caco-2 cells to
investigate apoptotic deletion. Cocultures of Caco-2 cells with B. longum resulted
positive in DNA fragmentation test, only when adherent strains were used (B12 and
B18). These results indicate that the interaction with adherent B. longum can induce
apoptotic deletion of Caco-2 cells, suggesting a role in cellular homeostasis of the
gastrointestinal tract and in restoring the ecology of damaged colon tissues. These
results were used to keep on researching and the strains tested were used as recipient
of recombinant techniques aimed to originate new B.longum strains with enhanced
capacity of apoptotic induction in “damaged” intestinal cells. To achieve this new
goal it was decided to clone the serpin encoding gene of B. longum, so that we can
understand its role in adhesion and apoptosis induction. Bifidobacterium longum has
immunostimulant activity that in vitro can lead to apoptotic response of Caco-2 cell
line. It secretes a hypothetical eukaryotic type serpin protein, which could be
involved in this kind of deletion of damaged cells. We had previously characterised a
protein that has homologies with the hypothetical serpin of B. longum (DD087853).
In order to create Bifidobacterium serpin transformants, a B. longum cosmid library
was screened with a PCR protocol using specific primers for serpin gene. After
fragment extraction, the insert named S1 was sub-cloned into pRM2, an Escherichia
coli - Bifidobacterium shuttle vector, to construct pRM3. Several protocols for B.
longum transformation were performed and the best efficiency was obtained using
MRS medium and raffinose. Finally bacterial cell supernatants were tested in a dotblot
assay to detect antigens presence against anti-antitrypsin polyclonal antibody.
The best signal was produced by one starin that has been renamed B. longum BLKS
7. Our research study was aimed to generate transformants able to over express serpin
encoding gene, so that we can have the tools for a further study on bacterial apoptotic
induction of Caco-2 cell line.
After that we have originated new trasformants the next step to do was to test
transformants abilities when exposed to an intestinal cell model. In fact, this part of
the project was achieved in the Department of Biochemistry of the Medical Faculty
of the University of Maribor, guest of the abroad supervisor of the Co-Advisorship
Doctoral Thesis: Prof. Avrelija Cencic. In this study we examined the probiotic
ability of some bacterial strains using intestinal cells from a 6 years old pig. The use
of intestinal mammalian cells is essential to study this symbiosis and a functional cell
model mimics a polarised epithelium in which enterocytes are separated by tight
junctions.
In this list of strains we have included the Bifidobacterium longum BKS7
transformant strain that we have previously originated; in order to compare its
abilities. B. longum B12 wild type and B. longum BKS7 transformant and eight
Lactobacillus strains of different sources were co-cultured with porcine small
intestine epithelial cells (PSI C1) and porcine blood monocytes (PoM2) in Transwell
filter inserts. The strains, including Lb. gasseri, Lb. fermentum, Lb. reuterii, Lb.
plantarum and unidentified Lactobacillus from kenyan maasai milk and tanzanian
coffee, were assayed for activation of cell lines, measuring nitric oxide by Griess
reaction, H202 by tetramethylbenzidine reaction and O2
- by cytochrome C reduction.
Cytotoxic effect by crystal violet staining and induction on metabolic activity by
MTT cell proliferation assay were tested too. Transepithelial electrical resistance
(TER) of polarised PSI C1 was measured during 48 hours co-culture. TER, used to
observe epithelium permeability, decrease during pathogenesis and tissue becomes
permeable to ion passive flow lowering epithelial barrier function. Probiotics can
prevent or restore increased permeability. Lastly, dot-blot was achieved against
Interleukin-6 of treated cells supernatants. The metabolic activity of PoM2 and PSI
C1 increased slightly after co-culture not affecting mitochondrial functions. No strain
was cytotoxic over PSI C1 and PoM2 and no cell activation was observed, as
measured by the release of NO2, H202 and O2
- by PoM2 and PSI C1. During coculture
TER of polarised PSI C1 was two-fold higher comparing with constant TER
(~3000 ) of untreated cells. TER raise generated by bacteria maintains a low
permeability of the epithelium. During treatment Interleukin-6 was detected in cell
supernatants at several time points, confirming immunostimulant activity. All results
were obtained using Lactobacillus paracasei Shirota e Carnobacterium divergens as
controls. In conclusion we can state that both the list of putative probiotic bacteria
and our new transformant strain of B. longum are not harmful when exposed to
intestinal cells and could be selected as probiotics, because can strengthen epithelial
barrier function and stimulate nonspecific immunity of intestinal cells on a pig cell
model. Indeed, we have found out that none of the strains tested that have good
adhesion abilities presents citotoxicity to the intestinal cells and that non of the strains
tested can induce cell lines to produce high level of ROS, neither NO2. Moreover we
have assayed even the capacity of producing certain citokynes that are correlated with
immune response. The detection of Interleukin-6 was assayed in all our samples,
including B.longum transformant BKS 7 strain, this result indicates that these bacteria
can induce a non specific immune response in the intestinal cells. In fact, when we
assayed the presence of Interferon-gamma in cells supernatant after bacterial
exposure, we have no positive signals, that means that there is no activation of a
specific immune response, thus confirming that these bacteria are not recognize as
pathogen by the intestinal cells and are certainly not harmful for intestinal cells. The
most important result is the measure of Trans Epithelial Electric Resistance that have
shown how the intestinal barrier function get strengthen when cells are exposed to
bacteria, due to a reduction of the epithelium permeability. We have now a new strain
of B. longum that will be used for further studies above the mechanism of apoptotic
induction to “damaged cells” and above the process of “restoring ecology”. This
strain will be the basis to originate new transformant strains for Serpin encoding gene
that must have better performance and shall be used one day even in clinical cases as
in “gene therapy” for cancer treatment and prevention.
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