Elena Papis

Engineered cobalt oxide nanoparticles readily enter cells

Magnetic nanoparticles (NPs) have great potential for applications not only as catalysts or energy storage devices, but also in biomedicine, as contrast enhancement agents for magnetic resonance imaging, or for drug delivery. The same characteristics that make cobalt-based NPs so attractive raise serious questions about their safety. In this context, we investigated Co3O4-NPs. Believing that the characterization of NPs is relevant for understanding their biological activity, we analyzed them by atomic force and electron microscopy to define size, shape, and aggregation. To clarify whether their biological effects could be due to a potential release of cobalt ions, we evaluated spontaneous dissolution in different media. To determine their potential toxicity to human cells, we measured cell viability and ROS formation in two human cell lines using CoCl2 for comparison. Co3O(4)-NPs induced a concentration- and time-dependent impairment of cellular viability, although cobalt ions were more toxic. We also demonstrated that cobalt causes a rapid induction of ROS if supplied in the form of Co3O4-NPs rather than as ions. Moreover, we evaluated the cellular uptake of NPs. Interestingly, Co3O4-NPs are able to enter the cell very rapidly, remaining confined in vesicles inside the cytoplasm. They were found also inside the cell nuclei, though less frequently.

Gene expression in nanotoxicology: A search for biomarkers of exposure to cobalt particles and ions

Despite the wide use of nanoscale materials in several industrial applications as well as in biology and medicine, very little research has been carried out on the potential toxicity of nanoparticles. We had previously obtained 10 differentially expressed mRNAs in BALB3T3 fibroblasts exposed to different forms of cobalt, i.e., microparticles, nanoparticles, and ions. Those genes represented candidate biomarkers for indicating specific cellular effects after cobalt nanoparticle exposure. In the present paper, we have further evaluated the expression of those genes by real-time RT-PCR after exposure to different forms of cobalt. Moreover, we also tested some genes associated with cobalt toxicity, such as VEGF, HIF-1α, and Bnip3. We identified biomarkers that are sensitive to cobalt ions that we think to be the reactive form. Our data, in fact, are consistent with the possibility that Co-nano, due to their large surface area, once inside the cell dissolve and act as ions.

Molecular cloning and expression of α2,8-sialyltransferase (ST8Sia I, GD3 Synthase) in Xenopus

GD3, a minor ganglioside in most normal tissues, is involved in important biological events and its expression could increase in pathological conditions. Organism integrity requires a tight balance between the anabolic and catabolic processes, thus it is important to control the intracellular expression of those “key” enzymes, which act at the “branching point” of ganglioside metabolism; one of these is the GD3-synthase (ST8Sia I). In this paper, we report the sequences of two ST8Sia I mRNAs found in Xenopus laevis and their genomic organization; the canonical form resulted constituted of 5 exons and 4 introns, while the “short” mRNA lacks of the exon 2. The expression of the two ST8Sia I mRNAs during embryo development and their tissue distribution in adult animals showed the single or simultaneous presence of the two forms. Experiments of in vitro expression and evaluation of enzymatic activity of the two hypothetical proteins turned out to be ST8Sia I. In the end, considering the growing interest toward the specie Xenopus tropicalis, due to its diploid genome that render it more suitable for genetic studies, we also cloned X. tropicalis ST8Sia I.

EST projects in aquaculture: sea bass, red tuna and perch

Riassunto Progetto EST in acquacoltura: spigola, tonno rosso e persico. Queste tre specie stanno richiamando un sempre maggior interesse. Si è reso quindi necessario effettuare un programma che permetta di valutare le abitudini comportamentali dei pesci di allevamento e gli eventuali problemi nelle varie fasi del ciclo biologico indagando, per esempio, l’espressione di geni coinvolti nella maturazione dei gameti e nella fecondazione e/o quelli che hanno un ruolo nella risposta di tipo biologico agli stressori ambientali. A tal fine abbiamo dato il via a questo progetto preparando una library di cDNA di fegato di branzino e sequenziando alcune centinaia di cloni il 55% dei quali risultano essere sequenze singole, mentre i restanti vanno a formare dei contig. Contemporaneamente è in corso uno studio sulle gonadi di tonno rosso e sul fegato di persico. L’ obiettivo di questo progetto è quello di creare database di sequenze di cDNA di queste tre specie di pesci ad interesse commerciale. Di tali library verranno sequenziati circa 5.000 cloni; le sequenze ottenute, depositate in banca dati, saranno disponibili via Internet a tutta la comunità scientifica che le potrà utilizzare per le ricerche più disparate.