23 resultados para Cellular and Molecular Physiology
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
The detection of Colorectal Cancer (CRC), at early stages, is one of the proven strategies resulting in a higher cure rate. In recent years, several studies have appeared identifying potential cancer markers in serum, plasma and stool in an attempt to improve actual screening procedures. Thus, the aim of the study was (1) Evaluate MN frequency, (2) Evaluate plasma ultrafiltrate capacity to induce MN formation, (3) Evaluate SEPT9 and NOTCH3 promoter methylation profile in peripheral blood lymphocytes from subjects resulted positive to fecal occult blood test and examined by colonoscopy. MN frequency was significantly higher in subjects with histological diagnosis of CRC and adenoma than control (p ≤ 0.001 and p ≤ 0.01, respectively). About, CF-MN analysis, a statistically significant difference was observed between CRC and control (p ≤ 0.05). On the other hand, SEPT9 and NOTCH3 promoter methylation status was significantly lower in CRC subjects than controls; additionally, NOTCH3 promoter methylation status was significantly lower in CRC subjects than adenoma subjects (p ≤ 0.01). The results obtained allow conclude that MN frequency varies according CRC pathologic status and, together with other variables, is a valid biomarker for adenoma and CRC risk. Additionally, the plasma of patients affected with CRC not only serve as a biomarker for oxidative stress but also as biomarker of genetic damage correlated with the carcinogenic process that verifies in colon-rectum. SEPT9 and NOTCH3 promoter methylation status, at peripheral blood level, varies according hystopathological changes observed in colon-rectum, suggesting that promoter methylation profile of these genes could be a reliable biomarker for CRC risk.
Resumo:
Cross Reacting Material 197(CRM197) is a Diphteria toxin non toxic mutant that had shown anti-tumor activity in mice and humans. CRM197 is utilized as a specific inhibitor of heparin-binding epidermal growth factor (HB-EGF), that competes for the epidermal growth factor receptor (EGFR), overexpressed in colorectal cancer and implicated in its progression. We evaluated the effects of CRM197 on HT-29 human colon cancer cell line behaviour and, for CRM197 recognized ability to inhibit HB-EGF, its possible effects on EGFR activation. In particular, while HT-29 does not show any reduction of viability after CRM197 treatment, or changes in cell cycle distribution, in EGFR localization or activation, they show a change in gene expression profile analyzed by microarray. This is the first study where the CRM197 treatment on HT-29 show the alteration of a specific and selected number of genes.
Resumo:
The dolphin (Tursiops truncatus) is a mammal that is adapted to life in a totally aquatic environment. Despite the popularity and even iconic status of the dolphin, our knowledge of its physiology, its unique adaptations and the effects on it of environmental stressors are limited. One approach to improve this limited understanding is the implementation of established cellular and molecular methods to provide sensitive and insightful information for dolphin biology. We initiated our studies with the analysis of wild dolphin peripheral blood leukocytes, which have the potential to be informative of the animal’s global immune status. Transcriptomic profiles from almost 200 individual samples were analyzed using a newly developed species-specific microarray to assess its value as a prognostic and diagnostic tool. Functional genomics analyses were informative of stress-induced gene expression profiles and also of geographical location specific transcriptomic signatures, determined by the interaction of genetic, disease and environmental factors. We have developed quantitative metrics to unambiguously characterize the phenotypic properties of dolphin cells in culture. These quantitative metrics can provide identifiable characteristics and baseline data which will enable identification of changes in the cells due to time in culture. We have also developed a novel protocol to isolate primary cultures from cryopreserved tissue of stranded marine mammals, establishing a tissue (and cell) biorepository, a new approach that can provide a solution to the limited availability of samples. The work presented represents the development and application of tools for the study of the biology, health and physiology of the dolphin, and establishes their relevance for future studies of the impact on the dolphin of environmental infection and stress.
Resumo:
A large body of literature documents in both mice and Drosophila the involvement of Insulin pathway in growth regulation, probably due to its role in glucose and lipid import, nutrient storage, and translation of RNAs implicated in ribosome biogenesis (Vanhaesebroeck et al. 2001). Moreover several lines of evidence implicate this pathway as a causal factor in cancer (Sale, 2008; Zeng and Yee 2007; Hursting et al., 2007; Chan et al., 2008). With regards to Myc, studies in cell culture have implied this family of transcription factors as regulators of the cell cycle that are rapidly induced in response to growth factors. Myc is a potent oncogene, rearranged and overexpressed in a wide range of human tumors and necessary during development. Its conditional knock-out in mice results in reduction of body weight due to defect in cell proliferation (Trumpp et al. 2001). Evidence from in vivo studies in Drosophila and mammals suggests a critical function for myc in cell growth regulation (Iritani and Eisenman 1999; Johnston et al. 1999; Kim et al. 2000; de Alboran et al. 2001; Douglas et al. 2001). This role is supported by our analysis of Myc target genes in Drosophila, which include genes involved in RNA binding, processing, ribosome biogenesis and nucleolar function (Orain et al 2003, Bellosta et al., 2005, Hulf et al, 2005). The fact that Insulin signaling and Myc have both been associated with growth control suggests that they may interact with each other. However, genetic evidence suggesting that Insulin signaling regulates Myc in vivo is lacking. In this work we were able to show, for the first time, a direct modulation of dMyc in response to Insulin stimulation/silencing both in vitro and in vivo. Our results suggest that dMyc up-regulation in response to DILPs signaling occurs both at the mRNA and potein level. We believe dMyc protein accumulation after Insulin signaling activation is conditioned to AKT-dependent GSK3β/sgg inactivation. In fact, we were able to demonstate that dMyc protein stabilization through phosphorylation is a conserved feature between Drosophila and vertebrates and requires multiple events. The final phosphorylation step, that results in a non-stable form of dMyc protein, ready to be degraded by the proteasome, is performed by GSK3β/sgg kinase (Sears, 2004). At the same time we demonstrated that CKI family of protein kinase are required to prime dMyc phosphorylation. DILPs and TOR/Nutrient signalings are known to communicate at several levels (Neufeld, 2003). For this reason we further investigated TOR contribution to dMyc-dependent growth regulation. dMyc protein accumulates in S2 cells after aminoacid stimulation, while its mRNA does not seem to be affected upon TORC1 inhibition, suggesting that the Nutrient pathway regulates dMyc mostly post-transcriptionally. In support to this hypothesis, we observed a TORC1-dependent GSK3β/sgg inactivation, further confirming a synergic effect of DILPs and Nutrients on dMyc protein stability. On the other hand, our data show that Rheb but not S6K, both downstream of the TOR kinase, contributes to the dMyc-induced growth of the eye tissue, suggesting that Rheb controls growth independently of S6K.. Moreover, Rheb seems to be able to regulate organ size during development inducing cell death, a mechanism no longer occurring in absence of dmyc. These observations suggest that Rheb might control growth through a new pathway independent of TOR/S6K but still dependent on dMyc. In order to dissect the mechanism of dMyc regulation in response to these events, we analyzed the relative contribution of Rheb, TOR and S6K to dMyc expression, biochemically in S2 cells and in vivo in morphogenetic clones and we further confirmed an interplay between Rheb and Myc that seems to be indipendent from TOR. In this work we clarified the mechanisms that stabilize dMyc protein in vitro and in vivo and we observed for the first time dMyc responsiveness to DILPs and TOR. At the same time, we discovered a new branch of the Nutrient pathway that appears to drive growth through dMyc but indipendently from TOR. We believe our work shed light on the mechanisms cells use to grow or restrain growth in presence/absence of growth promoting cues and for this reason it contributes to understand the physiology of growth control.
Resumo:
Gastroesophageal junction (GEJ) adenocarcinoma are uncommon before age of 40 years. While certain clinical, pathological and molecular features of GEJ adenocarcinoma in older patients have been extensively studied, these characteristics in the younger population remain to be determined. In the recent literature, a high sensitivity and specificity for the detection of dysplasia and esophageal adenocarcinoma was demonstrated by using multicolor fluorescence in situ hybridization (FISH) DNA probe set specific for the locus specific regions 9p21 (p16), 20q13.2 and Y chromosome. We evaluated 663 patients with GEJ adenocarcinoma and further divided them into 2 age-groups of
Resumo:
The productivity of agricultural crops is seriously limited by salinity. This problem is rapidly increasing, particularly in irrigated lands. Like almost all the fruit tree species, Pyrus communis is generally considered a salt sensitive species, but only little information is available on its behavior under saline conditions. Previous studies, carried out in the Department of Fruit Tree and Woody Plant Science (University of Bologna), focused their attention on pear and quince salt stress responses to understand which rootstock would be the most suitable for pear in order to tolerate a salt stress condition. It has been reported that pear and quince have different ability in the uptake, translocation and accumulation of chloride (Cl-) and sodium (Na+) ions, when plants were irrigated for one season with saline water (5 dS/m). The aim of the present work was to deepen these aspects and investigate salt stress responses in pear and quince. Two different experiments have been performed: a “short-term” trial in a growth chamber and a “long-term” experiment in the open field. In the short-term experiment, three different genotypes usually adopted as pear rootstocks (MC, BA29 and Farold®40) and the pear variety Abbé Fétel own rooted have been compared under salt stress conditions. The trial was performed in a hydroponic culture system, applying a 90 mM NaCl stress to half of the plants, after five weeks of normal growth in Hoagland’s solution. During the three-weeks of salt stress treatment, physiological, mineral and molecular analyses were performed in order to monitor, for each genotype, the development of the salt stress responses in comparison with the corresponding “unstressed” plants. Farold®40 and Abbé Fétel own rooted showed the onset of leaf necrosis, due to salt toxicity, one week before quinces. Moreover, quinces displayed a significant delay in premature senescence of old leaves, while pears emerged for their ability to regenerate new leaves from apparently dead foliage with the salt stress still running. Physiological measurements, such as shoots length, chlorophyll (Chl) content, and photosynthesis, have been carried out and revealed that pears exhibited a significant reduction in water content and a wilting aspect, while for quinces a decrease in Chl content and a growth slowdown were observed. At the end of the trial, all plants were collected and organs separated for dry weight estimation and mineral analyses (Cu, Fe, Mn, Zn Mg, Ca, K, Na and Cl). Mineral contents have been affected by salinity; same macro/micro nutrients were altered in some organs or relocated within the plant. This plant response could have partially contributed to face the salt stress. Leaves and roots have been harvested for molecular analyses at four different times during stress conditions. Molecular analyses consisted of the gene expression study of three main ion transporters, well known in Arabidopsis thaliana as salt-tolerance determinants in the “SOS” pathway: NHX1 (tonoplast Na+/H+ antiporter), SOS1 (plasmalemma Na+/H+ antiporter) and HKT1 (K+ high-affinity and Na+ low-affinity transporter). These studies showed that two quince rootstocks adopted different responsive mechanisms to NaCl stress. BA29 increased its Na+ sequestration activity into leaf vacuoles, while MC enhanced temporarily the same ability, but in roots. Farold®40, instead, exhibited increases in SOS1 and HKT1 expression mainly at leaf level in the attempt to retrieve Na+ from xylem, while Abbé Fétel differently altered the expression of these genes in roots. Finally, each genotype showed a peculiar response to salt stress that was the sum of its ability in Na+ exclusion, osmotic tolerance and tissue tolerance. In the long-term experiment, potted trees of the pear variety Abbé Fétel grafted on different rootstocks (MC, BA29 and Farold®40), or own rooted and also rootstocks only were subjected to a salt stress through saline water irrigation with an electrical conductivity of 5 dS/m for two years. The purposes of this study were to evaluate salinity effects on physiological (shoot length, number of buds, photosynthesis, etc.) and yield parameters of cultivar Abbé Fétel in the different combinations and to determine the salt amount that pear is able to tolerate over the years. With this work, we confirmed the previous hypothesis that pear, despite being classified as a salt-sensitive fruit tree, can be cultivated for two years under saline water irrigation, without showing any salt toxicity symptoms or severe drawbacks on plant development and production. Among different combinations, Abbé Fétel grafted on MC resulted interesting for its peculiar behaviors under salt stress conditions. In the near future, further investigations on physiological and molecular aspects will be necessary to enrich and broaden the knowledge of salt stress responses in pear.
Resumo:
Nuclear Magnetic Resonance (NMR) is a branch of spectroscopy that is based on the fact that many atomic nuclei may be oriented by a strong magnetic field and will absorb radiofrequency radiation at characteristic frequencies. The parameters that can be measured on the resulting spectral lines (line positions, intensities, line widths, multiplicities and transients in time-dependent experi-ments) can be interpreted in terms of molecular structure, conformation, molecular motion and other rate processes. In this way, high resolution (HR) NMR allows performing qualitative and quantitative analysis of samples in solution, in order to determine the structure of molecules in solution and not only. In the past, high-field NMR spectroscopy has mainly concerned with the elucidation of chemical structure in solution, but today is emerging as a powerful exploratory tool for probing biochemical and physical processes. It represents a versatile tool for the analysis of foods. In literature many NMR studies have been reported on different type of food such as wine, olive oil, coffee, fruit juices, milk, meat, egg, starch granules, flour, etc using different NMR techniques. Traditionally, univariate analytical methods have been used to ex-plore spectroscopic data. This method is useful to measure or to se-lect a single descriptive variable from the whole spectrum and , at the end, only this variable is analyzed. This univariate methods ap-proach, applied to HR-NMR data, lead to different problems due especially to the complexity of an NMR spectrum. In fact, the lat-ter is composed of different signals belonging to different mole-cules, but it is also true that the same molecules can be represented by different signals, generally strongly correlated. The univariate methods, in this case, takes in account only one or a few variables, causing a loss of information. Thus, when dealing with complex samples like foodstuff, univariate analysis of spectra data results not enough powerful. Spectra need to be considered in their wholeness and, for analysing them, it must be taken in consideration the whole data matrix: chemometric methods are designed to treat such multivariate data. Multivariate data analysis is used for a number of distinct, differ-ent purposes and the aims can be divided into three main groups: • data description (explorative data structure modelling of any ge-neric n-dimensional data matrix, PCA for example); • regression and prediction (PLS); • classification and prediction of class belongings for new samples (LDA and PLS-DA and ECVA). The aim of this PhD thesis was to verify the possibility of identify-ing and classifying plants or foodstuffs, in different classes, based on the concerted variation in metabolite levels, detected by NMR spectra and using the multivariate data analysis as a tool to inter-pret NMR information. It is important to underline that the results obtained are useful to point out the metabolic consequences of a specific modification on foodstuffs, avoiding the use of a targeted analysis for the different metabolites. The data analysis is performed by applying chemomet-ric multivariate techniques to the NMR dataset of spectra acquired. The research work presented in this thesis is the result of a three years PhD study. This thesis reports the main results obtained from these two main activities: A1) Evaluation of a data pre-processing system in order to mini-mize unwanted sources of variations, due to different instrumental set up, manual spectra processing and to sample preparations arte-facts; A2) Application of multivariate chemiometric models in data analy-sis.
Resumo:
It is well known that the best grape quality can occur only through the achievement of optimal source/sink ratio. Vine balance is in fact a key parameter in controlling berry sugar, acidity and secondary metabolites content (Howell, 2001; Vanden Heuvel et al., 2004). Despite yield reduction and quality improvement are not always strictly related, cluster thinning is considered a technique which could lead to improvement in grape sugar and anthocyanin composition (Dokoozlian and Hirschfelt, 1995; Guidoni et al., 2002). Among several microclimatic variables which may impact grape composition, the effect of cluster light exposure and temperature, which probably act in synergistic and complex way, has been widely explored showing positive even sometimes contradictory results (Spayd et al., 2001; Tarara et al., 2008). Pre-bloom and véraison defoliation are very efficient techniques in inducing cluster microclimatic modification. Furthermore pre-bloom defoliation inducing a lower berry set percentage On these basis the aim of the first experiment of the thesis was to verify in cv Sangiovese the effects on ripening and berry composition of management techniques which may increase source/sink ratio and /or promote light incidence on berries throughout grape ripening. An integrated agronomic, biochemical and microarray approach, aims to understand which mechanisms are involved in berry composition and may be conditioned in the berries during ripening in vines submitted to three treatments. In particular the treatments compared were: a) cluster thinning (increasing in source/sink ratio) b) leaf removal at véraison (increasing cluster light exposure) c) pre-bloom defoliation (increasing source sink ratio and cluster light exposure). Vine response to leaf removal at véraison was further evaluated in the second experiment on three different varieties (Cabernet Sauvignon, Nero d’Avola, Raboso Piave) chosen for their different genetic traits in terms of anthocyanin amount and composition. The integrated agronomic, biochemical and microarray approach, employed in order to understand those mechanisms involved in berry composition of Sangiovese vines submitted to management techniques which may increase source/sink ratio and induce microclimatic changes, bring to interesting results. This research confirmed the main role of source/sink ratio in conditioning sugars metabolism and revealed also that carbohydrates availability is a crucial issue in triggering anthocyanin biosynthesis. More complex is the situation of pre-bloom defoliation, where source/sink and cluster light increase effects are associated to determine final berry composition. It results that the application of pre-bloom defoliation may be risky, as too much dependent on seasonal conditions (rain and temperature) and physiological vine response (leaf area recovery, photosynthetic compensation, laterals regrowth). Early induced stress conditions could bring cluster at véraison in disadvantage to trigger optimal berry ripening processes compared to untreated vines. This conditions could be maintained until harvest, if no previously described physiological recovery occurs. Certainly, light exposure increase linked to defoliation treatments, showed a positive and solid effect on flavonol biosynthesis, as in our conditions temperature was not so different among treatments. Except the last aspects, that could be confirmed also for véraison defoliation, microclimatic changes by themselves seemed not able to induce any modification in berry composition. Further studies are necessary to understand if the peculiar anthocyanic and flavonols composition detected in véraison defoliation could play important role in both color intensity and stability of wines.
Resumo:
Alzheimer's disease (AD) is probably caused by both genetic and environmental risk factors. The major genetic risk factor is the E4 variant of apolipoprotein E gene called apoE4. Several risk factors for developing AD have been identified including lifestyle, such as dietary habits. The mechanisms behind the AD pathogenesis and the onset of cognitive decline in the AD brain are presently unknown. In this study we wanted to characterize the effects of the interaction between environmental risk factors and apoE genotype on neurodegeneration processes, with particular focus on behavioural studies and neurodegenerative processes at molecular level. Towards this aim, we used 6 months-old apoE4 and apoE3 Target Replacement (TR) mice fed on different diets (high intake of cholesterol and high intake of carbohydrates). These mice were evaluated for learning and memory deficits in spatial reference (Morris Water Maze (MWM)) and contextual learning (Passive Avoidance) tasks, which involve the hippocampus and the amygdala, respectively. From these behavioural studies we found that the initial cognitive impairments manifested as a retention deficit in apoE4 mice fed on high carbohydrate diet. Thus, the genetic risk factor apoE4 genotype associated with a high carbohydrate diet seems to affect cognitive functions in young mice, corroborating the theory that the combination of genetic and environmental risk factors greatly increases the risk of developing AD and leads to an earlier onset of cognitive deficits. The cellular and molecular bases of the cognitive decline in AD are largely unknown. In order to determine the molecular changes for the onset of the early cognitive impairment observed in the behavioural studies, we performed molecular studies, with particular focus on synaptic integrity and Tau phosphorylation. The most relevant finding of our molecular studies showed a significant decrease of Brain-derived Neurotrophic Factor (BDNF) in apoE4 mice fed on high carbohydrate diet. Our results may suggest that BDNF decrease found in apoE4 HS mice could be involved in the earliest impairment in long-term reference memory observed in behavioural studies. The second aim of this thesis was to study possible involvement of leptin in AD. There is growing evidence that leptin has neuroprotective properties in the Central Nervous System (CNS). Recent evidence has shown that leptin and its receptors are widespread in the CNS and may provide neuronal survival signals. However, there are still numerous questions, regarding the molecular mechanism by which leptin acts, that remain unanswered. Thus, given to the importance of the involvement of leptin in AD, we wanted to clarify the function of leptin in the pathogenesis of AD and to investigate if apoE genotype affect leptin levels through studies in vitro, in mice and in human. Our findings suggest that apoE4 TR mice showed an increase of leptin in the brain. Leptin levels are also increased in the cerebral spinal fluid of AD patients and apoE4 carriers with AD have higher levels of leptin than apoE3 carriers. Moreover, leptin seems to be expressed by reactive glial cells in AD brains. In vitro, ApoE4 together with Amyloid beta increases leptin production by microglia and astrocytes. Taken together, all these findings suggest that leptin replacement might not be a good strategy for AD therapy. Our results show that high leptin levels were found in AD brains. These findings suggest that, as high leptin levels do not promote satiety in obese individuals, it might be possible that they do not promote neuroprotection in AD patients. Therefore, we hypothesized that AD brain could suffer from leptin resistance. Further studies will be critical to determine whether or not the central leptin resistance in SNC could affect its potential neuroprotective effects.
Resumo:
Grape berry is considered a non climacteric fruit, but there are some evidences that ethylene plays a role in the control of berry ripening. This PhD thesis aimed to give insights in the role of ethylene and ethylene-related genes in the regulation of grape berry ripening. During this study a small increase in ethylene concentration one week before véraison has been measured in Vitis vinifera L. ‘Pinot Noir’ grapes confirming previous findings in ‘Cabernet Sauvignon’. In addition, ethylene-related genes have been identified in the grapevine genome sequence. Similarly to other species, biosynthesis and ethylene receptor genes are present in grapevine as multi-gene families and their expression appeared tissue or developmental specific. All the other elements of the ethylene signal transduction cascade were also identified in the grape genome. Among them, there were ethylene response factors (ERF) which modulate the transcription of many effector genes in response to ethylene. In this study seven grapevine ERFs have been characterized and they showed tissue and berry development specific expression profiles. Two sequences, VvERF045 and VvERF063, seemed likely involved in berry ripening control due to their expression profiles and their sequence annotation. VvERF045 was induced before véraison and was specific of the ripe berry, by sequence similarity it was likely a transcription activator. VvERF063 displayed high sequence similarity to repressors of transcription and its expression, very high in green berries, was lowest at véraison and during ripening. To functionally characterize VvERF045 and VvERF063, a stable transformation strategy was chosen. Both sequences were cloned in vectors for over-expression and silencing and transferred in grape by Agrobacterium-mediated or biolistic-mediated gene transfer. In vitro, transgenic VvERF045 over-expressing plants displayed an epinastic phenotype whose extent was correlated to the transgene expression level. Four pathogen stress response genes were significantly induced in the transgenic plants, suggesting a putative function of VvERF045 in biotic stress defense during berry ripening. Further molecular analysis on the transgenic plants will help in identifying the actual VvERF045 target genes and together with the phenotypic characterization of the adult transgenic plants, will allow to extensively define the role of VvERF045 in berry ripening.
Resumo:
Traditional morphological examinations are not anymore sufficient for a complete evaluation of tumoral tissue and the use of neoplastic markers is of utmost importance. Neoplastic markers can be classified in: diagnostic, prognostic and predictive markers. Three markers were analyzed. 1) Insulin-like growth factor binding protein 2 (IGFBP2) was immunohistochemically examined in prostatic tissues: 40 radical prostatectomies from hormonally untreated patients with their preoperative biopsies, 10 radical prostatectomies from patients under complete androgen ablation before surgery and 10 simple prostatectomies from patients with bladder outlet obstruction. Results were compared with α-methylacyl-CoA racemase (AMACR). IGFBP2 was expressed in the cytoplasm of untreated adenocarcinomas and, to a lesser extent, in HG-PIN; the expression was markedly lower in patients after complete androgen ablation. AMACR was similarly expressed in both adenocarcinoma and HG-PIN, the level being similar in both lesions; the expression was slightly lower in patients after complete androgen ablation. IGFBP2 may be used a diagnostic marker of prostatic adenocarcinomas. 2) Heparan surface proteoglycan immunohistochemical expression was examined in 150 oral squamous cell carcinomas. Follow up information was available in 93 patients (range: 6-34 months, mean: 19±7). After surgery, chemotherapy was performed in 8 patients and radiotherapy in 61 patients. Multivariate and univariate overall survival analyses showed that high expression of syndecan-1 (SYN-1) was associated with a poor prognosis. In patients treated with radiotherapy, such association was higher. SYN-1 is a prognostic marker in oral squamous cell carcinomas; it may also represent a predictive factor for responsiveness to radiotherapy. 3) EGFR was studied in 33 pulmonary adenocarcinomas with traditional DNA sequencing methods and with two mutation-specific antibodies. Overall, the two antibodies had 61.1% sensitivity and 100% specificity in detecting EGFR mutations. EGFR mutation-specific antibodies may represent a predictive marker to identify patients candidate to tyrosine kinase inhibitors therapy.