Dinamiche molecolari associate al fattore di trascrizione Xrx1 nello sviluppo retinico di Xenopus laevis

Riassunto Il fattore di trascrizione Xrx1 gioca un ruolo chiave nell'ontogenesi e nella patologia dell'occhio. Esperimenti di microarray, validati in vitro ed in vivo, hanno condotto alla definizione di un set di geni da esso putativamente regolati. Il presente progetto di tesi si propone affinare la comprensione degli effetti di Xrx1 attraverso la caratterizzazione funzionale di fattori selezionati all'interno della lista di geni sopracitata. Per mezzo di una procedura bioinformatica semi-automatizzata si sono ricercati possibili bersagli diretti di Xrx1. Inoltre, nei geni regolati da Xrx1 sono stati individuati siti di legame per altri fattori di trascrizione. Sulla base dei dati raccolti, ed alla luce delle informazioni precedentemente ottenute nonché delle nozioni già presenti in letteratura, si sono condotti esperimenti di ibridazione in situ tesi a confermare l'espressione retinica di due geni selezionati: Groucho ed E2A. Si sono poi effettuati clonaggi della sola regione codificante atti alla produzione di mRNA funzionali. Esperimenti di sovraespressione degli mRNA hanno portato alla scoperta di una variazione del dominio di espressione di un marcatore del territorio presuntivo dell'occhio (Pax6) per Groucho, e di alterazioni morfologiche nel caso di E2A. Successivi esperimenti si rendono necessari per la completa caratterizzazione degli effetti osservati. Abstract The transcription factor Xrx1 plays a crucial role in eye development and pathology. Microarray experiments, validated in vitro and in vivo, led to the definition of a set of genes putatively regulated by it. This dissertation project aims at refining the effects of Xrx1 through the functional characterization of selected factors belonging to the already cited list. By a semi-automatic bioinformatic pipeline, putative direct targets of Xrx1 have been searched. Other transcription factor binding sites have also been identified in the same set of genes. On the basis of the collected data, database and literature information, in situ hybridization experiments were performed in order to confirm the retinal expression for two selected genes: Groucho and E2A. Molecular cloning of the two coding regions was then performed in order to produce functional mRNA. Overexpression of the two mRNAs led to the discovery of a variation in the expression pattern of an eye field marker (Pax6) for Groucho, and to morphological alterations in the case of E2A. Further analyses are needed to the full understanding of the observed effects

Superparamagnetic iron oxide nanoparticles for magnetic hyperthermia: recent advancements, molecular effects, and future directions in the omics era.

Coating and targeting strategies improve superparamagnetic iron oxide nanoparticles-induced hyperthermia, while omics can unveil molecular effects

Ultrasound-Activated Piezoelectric Nanoparticles Inhibit Proliferation of Breast Cancer Cells

Abstract A nanotechnology-based approach for the inhibition of breast cancer cell proliferation is proposed. The innovative solution consists in a platform based on biocompatible piezoelectric nanoparticles able to target and remotely stimulate HER2-positive breast cancer cells. The anti-proliferative effects of the ultrasound-driven piezoelectric nanoparticle-assisted stimulation significantly reduced the proliferation by inducing the cell cycle arrest. Similarly to a low-intensity alternating electric field, chronic piezoelectric stimulation resulted able to inhibit cancer cell proliferation by upregulating the expression of the gene encoding Kir3.2 inward rectifier potassium channels, by interfering on Ca2+ homeostasis, and by affecting the organization of mitotic spindles during mitosis. The proposed platform, even if specific for HER2-positive cells, shows huge potential and versatility for the treatment of different type of cancers

pp60v-src phosphorylates and activates low molecular weight phosphotyrosine-protein phosphatase.

Low M(r) phosphotyrosine-protein phosphatase belongs to the non-receptor cytosolic phosphotyrosine-protein phosphatase subfamily. It has been demonstrated that this enzyme dephosphorylates receptor tyrosine kinases, namely the epidermal growth factor receptor in vitro and the platelet-derived growth factor receptor in vivo. Low M(r) phosphotyrosine-protein phosphatase is constitutively tyrosine-phosphorylated in NIH/3T3 cells transformed by pp60v-src. The same tyrosine kinase, previously immunoprecipitated, phosphorylates this enzyme in vitro as well. Phosphorylation is enhanced using phosphatase inhibitors and phenylarsine oxide-inactivated phosphatase, consistently with the existence of an auto-dephosphorylation process. Intermolecular dephosphorylation is demonstrated adding the active enzyme in a solution containing the inactivated and previously phosphorylated one. This tyrosine phosphorylation correlates with an increase in catalytic activity. Our results provide evidence of a physiological mechanism of low M(r) phosphotyrosine-protein phosphatase activity regulation

Productive performances of Maremmana young bulls reared following organic rules and slaughtered at 18 and 24 months of age

Fourteen Maremmana young bulls fed on pastures supplemented with mixed hay and concentrates, according to an organic method, were slaughtered at 18 and 24 months of age to evaluate in vita and post-mortem performances. At slaughter, carcass yield was determined and carcass evaluation according to EU rules wasmade. Physico-chemical characteristics of Longissimus thoracis (LT) and Caput longum triceps brachii (TB) muscles were determined. No differences for both carcass yield and quality were found between the two age groups. Animals of 24 months of age presented lighter and more yellow meat as well as higher hue angle and drip loss. TB muscle showed lower protein content and higher shear force, moisture, total lipids and ash than LT. The latter presented a higher percentage of C15iso, whereas TB showed higher values of C18:2n6, C20:3n6, C20:4n6, C18:3n3 and C22:5n3. Maremmana animals, irrespective of age, showed a low percentage of saturated fatty acids, good PUFA/SFA ratio and a great amount of unsaturated fatty acids of the n3 and n6 series, as well as a favorable atherogenicity and thrombogenicity indexes

Evaluation of biocompatibility, osteointegration and biomechanical properties of the new Calcemex® cement: an in vivo study

The mixture of polymethylmethacrylate (PMMA) and β-tricalciumphospate (β-TCP) is the most widely used bone graft. Common features of bone cement are the biocompatibility, bioactivity, mechanical stability and ability to fuse with the host's bone tissue. However, there are still few studies that have evaluated these characteristics in vivo. Our study aims to acquire these parameters, using an animal model with functional characteristics similar to those of humans. The analyzed cement is Calcemex®, evaluated both in compact and fluid formulation. The chosen animal models were 5 pigs, treated with femoral and tibial implants of Calcemex® samples. After one year, the pigs were sacrificed and the specimens explanted for morphological, histological, ultrastructural and mechanical evaluations. For both formulations, the investigation highlighted the absence of foreign body reactions in the host, the histological integration with the surrounding tissues and the preservation of mechanical compression resistance

Kdm7a expression is spatiotemporally regulated in developing Xenopus laevis embryos, and its overexpression influences late retinal development

Background: Post-translational histone modifications are among the most common epigenetic modifications that orchestrate gene expression, playing a pivotal role during embryonic development and in various pathological conditions. Among histone lysine demethylases, KDM7A, also known as KIAA1718 or JHDM1D, catalyzes the demethylation of H3K9me1/2 and H3K27me1/2, leading to transcriptional regulation. Previous data suggest that KDM7A plays a central role in several biological processes, including cell proliferation, commitment, differentiation, apoptosis, and maintenance. However, information on the expression pattern of KDM7A in whole organisms is limited, and its functional role is still unclear. Results: In Xenopus development, kdm7a is expressed early, undergoing spatiotemporal regulation in various organs and tissues, including the central nervous system and the eye. Focusing on retinal development, we found that kdm7a overexpression does not affect the expression of genes critically involved in early neural development and eye-field specification, whereas unbalances the distribution of neural cell subtypes in the mature retina by disfavoring the development of ganglion cells while promoting that of horizontal cells. Conclusions: Kdm7a is dynamically expressed during embryonic development, and its overexpression influences late retinal development, suggesting a potential involvement in the molecular machinery regulating the spatiotemporally ordered generation of retinal neuronal subtypes

Tannic Acid-Iron Complex-Based Nanoparticles as a Novel Tool against Oxidative Stress

: Accumulation of reactive oxygen species in cells leads to oxidative stress, with consequent damage for cellular components and activation of cell-death mechanisms. Oxidative stress is often associated with age-related conditions, as well as with several neurodegenerative diseases. For this reason, antioxidant molecules have attracted a lot of attention, especially those derived from natural sources─like polyphenols and tannins. The main issue related to the use of antioxidants is their inherent tendency to be oxidized, their quick enzymatic degradation in biological fluids, and their poor bioavailability. Nanomedicine, in this sense, has helped in finding new solutions to deliver and protect antioxidants; however, the concentration of the encapsulated molecule in conventional nanosystems could be very low and, therefore, less effective. We propose to exploit the properties of tannic acid, a known plant-derived antioxidant, to chelate iron ions, forming hydrophobic complexes that can be coated with a biocompatible and biodegradable phospholipid to improve stability in biological media. By combining nanoprecipitation and hot sonication procedures, we obtained three-dimensional networks composed of tannic acid-iron with a hydrodynamic diameter of ≈200 nm. These nanostructures show antioxidant properties and scavenging activity in cells after induction of an acute chemical pro-oxidant insult; moreover, they also demonstrated to counteract damage induced by oxidative stress both in vitro and on an in vivo model organism (planarians)

Electro-optically tunable microring resonators in lithium niobate

Optical microresonators have recently attracted a growing attention in the photonics community. Their applications range from quantum electro-dynamics to sensors and filtering devices for optical telecommunication systems, where they are likely to become an essential building block. The integration of nonlinear and electro-optical properties in the resonators represents a very stimulating challenge, as it would incorporate new and more advanced functionality. Lithium niobate is an excellent candidate material, being an established choice for electro-optic and nonlinear optical applications. Here we report on the first realization of optical microring resonators in submicrometric thin films of lithium niobate. The high index contrast films are produced by an improved crystal ion slicing and bonding technique using benzocyclobutene. The rings have radius R=100 um and their transmission spectrum has been tuned using the electro-optic effect. These results open new perspectives for the use of lithium niobate in chip-scale integrated optical devices and nonlinear optical microcavities.Comment: 15 pages, 8 figure