HORMONAL NETWORK CONTROLLING THE OVULE DEVELOPMENT IN ARABIDOPSIS THALIANA

During my Ph.D., I have focused my research to uncover the molecular network controlling ovule development in Arabidopsis thaliana. This thesis is organized in an introduction part, in which I have described what it is known about ovule development including the description of the role of hormones. Then, in chapter 1, I have described the research performed to study the role of auxin and auxin polar transport in ovule development. Chapter 2 is focalized on the study that I have performed to identify and characterized genes involved in auxin biosynthesis during ovule development in Arabidopsis. Chapter 3 described the results obtained manipulating the cytokinin amount in ovule. Cytokinins have an antagonistic role respect to auxin during differentiation and development. I have studied cytokinins pathway using specific markers line and by genetic approaches. In the work proposed in the Chapter 4 the studies on the influence of auxin, cytokinin and transcription factor on ovule development, converge in one single line of investigation and a model for ovule organogenesis is proposed. In the last chapter the final discussion is presented with a general overview of the results and the suggestion of future experiments that could be performed in the near future

Effects of PAHs and dioxins on the earthworm Eisenia andrei: a multivariate approach for biomarker interpretation.

In this study, a battery of biomarkers was utilised to evaluate the stress syndrome induced in the earthworm Eisenia andrei by exposure to environmentally realistic concentrations of benzo[a]pyrene (B[a]P) and 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) in OECD soil. The set of tests was then employed to assess the toxicity of field soils contaminated with organic xenobiotic compounds (such as PAHs, dioxins and PCBs). Biomarker responses (comprising biomarkers of stress and of genotoxicity) varied depending on chemicals, dose and time of exposure; and among the different polluted field soils. The results highlighted an impairment of immune and metabolic functions and genotoxic damage in worms exposed also to lower bioavailable concentrations of toxic chemicals. Multivariate analysis of biomarker data showed that all different contaminated soils had a detrimental effect on the earthworms; control animals being clearly separated from the treated ones. A separation between temporal and concentration factors were also evident for B[a]P and TCDD treatments; and field contaminated soils were further differentiated reflecting a diverse contamination. Multivariate analysis also demonstrated that lysosomal membrane stability can be considered as a predictive tool of the adverse effects on worm health status provoked by increasing bioavailable concentrations of toxic chemicals

Tailored treatment for signet ring cell gastric cancer

Gastric cancer with Laur\ue8n diffuse types is increasing in the West. The raising trend is more evident when considering signet ring cells (SRC) histology. However, to control the biologic potential of this GC subtype, some hypotheses of tailored therapeutic strategies for SRC cancers have been made. A review of the literature was performed using the key words "signet ring cells" AND "gastric cancer". Results of literature review were descriptively reported. Endoscopic submucosal dissection (ESD), according to the Japanese extended criteria, could be a therapeutic option for early SRC tumours. However, according to the evidences from more recent studies, indications for ESD to these tumours types should be carefully considered. Concerning the optimal surgical treatment, considering the high lymphotropism and infiltrating behaviour of SRC histotype, the extension of gastric resection should be wider than for intestinal type cancer and laparoscopic surgery should be performed carefully. Moreover, D3 lymphadenectomy could provide a benefit in diffuse-type and SRC histology. The role of surgery in gastric cancer with peritoneal carcinomatosis is still debated and studies on this topic should stratify the good results according to GC histotype. Finally, despite the evidences of chemoresistance in SRC, ongoing randomized trials suggest that multimodal therapy could be the best treatment. Based on the assumption that SRC tumours have specific features, they deserve a specific multimodal treatment. However, a preliminary step to generate strong evidences in this field is the standardization of terminology used to define signet ring cells carcinoma

Acute bleeding obstruction pancreatitis after Roux-en-Y anastomosis in total gastrectomy: a single center experience

Anastomotic intraluminal bleeding is a well-known complication after total gastrectomy. Nevertheless, few data are published on acute bleeding obstruction pancreatitis (BOP) due to a bleeding from the jejunojejunostomy (JJ). In this paper we describe our experience. A total of 140 gastrectomies for EGJ cancer were performed in our Institute from January 2012 to January 2017. All reconstructions were performed with a Roux-en-Y anastomosis: a mechanical end-to-side esophago-jejunostomy and a mechanical end-to-side JJ. Three patients suffered from a bleeding at the JJ with a consequent BOP. We analyzed the time of diagnosis, the treatment and the outcomes. The three patients presented anemia at the laboratory findings on postoperative day (POD) 1. In patient I laboratory findings of acute pancreatitis were found in POD 2. CT scan was performed and showed signs of BOP. Endoscopic treatment was tried without success. Therefore, patient underwent surgery: JJ take down, bleeding control and anastomosis rebuild were performed. In spite of this the patient died of MOF in POD 4. Patient II had a persistent anemia treated with blood transfusions until POD 3, when laboratory tests showed increased lipase and bilirubin levels. Patient was successfully treated with endoscopy but several blood transfusions and a prolonged recovery were necessary. Patient III had laboratory findings of acute pancreatitis on POD 1. Immediate surgery was performed and patient was discharged on POD 9 without sequelae. BOP is a rare but deadly complication after Roux-en-Y anastomosis. An early diagnosis and an aggressive treatment seem to improve the outcome

Inventories and the Stockout Constraint in General Equilibrium

We study the implications of a stockout constraint in a dynamic general equilibrium model, which can explain both standard business cycle and inventory facts. Under this constraint, inventories and demand are complements in generating sales, and hence the optimal level of inventories increases in expected demand. We show that the inventory to sales ratio is both persistent and countercyclical because the cost of carrying inventories is mainly determined by the interest rate. We use this model to disentangle output and sales, by matching the key inventory moments, and find that preference and productivity shocks are equally important in the data. Finally, we assess whether improvements in inventory management can explain the Great Moderation. We find that, although improvements in inventory management can reduce the need for inventory holdings, which decreases output volatility relative to sales volatility, lower levels of inventories actually increases sales volatility. Because these two effects offset each other, a change in inventory management does not change output volatility to any great extent

The mixed longitudinal–transverse nature of collective modes in water

We report high-resolution, high-statistics inelastic x-ray scattering measurements of the dynamic structure factor of water as a function of momentum and energy transfer in various thermodynamic conditions, including high-pressure liquid near the melting point, supercooled liquid and polycrystalline ice. For momentum transfer values below 8 nm−1, two collective excitations associated with longitudinal and transverse acoustic modes were observed. Above 8 nm−1, another excitation was detected in the liquid. Comparison with polycrystalline data and molecular dynamics simulations suggests that this mode is related to longitudinal–transverse mixing of mode symmetry

Free electron laser-driven ultrafast rearrangement of the electronic structure in Ti

High-energy density extreme ultraviolet radiation delivered by the FERMI seeded free-electron laser has been used to create an exotic nonequilibrium state of matter in a titanium sample characterized by a highly excited electron subsystem at temperatures in excess of 10 eV and a cold solid-density ion lattice. The obtained transient state has been investigated through ultrafast absorption spectroscopy across the Ti M2,3-edge revealing a drastic rearrangement of the sample electronic structure around the Fermi level occurring on a time scale of about 100 fs

Nanoscale transient magnetization gratings excited and probed by femtosecond extreme ultraviolet pulses

We utilize coherent femtosecond extreme ultraviolet (EUV) pulses derived from a free electron laser (FEL) to generate transient periodic magnetization patterns with periods as short as 44 nm. Combining spatially periodic excitation with resonant probing at the dichroic M-edge of cobalt allows us to create and probe transient gratings of electronic and magnetic excitations in a CoGd alloy. In a demagnetized sample, we observe an electronic excitation with 50 fs rise time close to the FEL pulse duration and ~0.5 ps decay time within the range for the electron-phonon relaxation in metals. When the experiment is performed on a sample magnetized to saturation in an external field, we observe a magnetization grating, which appears on a sub-picosecond time scale as the sample is demagnetized at the maxima of the EUV intensity and then decays on the time scale of tens of picoseconds via thermal diffusion. The described approach opens prospects for studying dynamics of ultrafast magnetic phenomena on nanometer length scales

Integration of multiple platforms for the analysis of multifluorescent marking technology applied to pediatric GBM and dipg

The intratumor heterogeneity represents one of the most difficult challenges for the development of effective therapies to treat pediatric glioblastoma (pGBM) and diffuse intrinsic pontine glioma (DIPG). These brain tumors are composed of heterogeneous cell subpopulations that coexist and cooperate to build a functional network responsible for their aggressive phenotype. Understanding the cellular and molecular mechanisms sustaining such network will be crucial for the identification of new therapeutic strategies. To study more in-depth these mechanisms, we sought to apply the Multifluorescent Marking Technology. We generated multifluorescent pGBM and DIPG bulk cell lines randomly expressing six different fluorescent proteins and from which we derived stable optical barcoded single cell-derived clones. In this study, we focused on the application of the Multifluorescent Marking Technology in 2D and 3D in vitro/ex vivo culture systems. We discuss how we integrated different multimodal fluorescence analysis platforms, identifying their strengths and limitations, to establish the tools that will enable further studies on the intratumor heterogeneity and interclonal interactions in pGBM and DIPG