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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.11.044 Byline: Andrea Lunardi (a), Federico Cremisi (b), Luciana Dente (a) Keywords: Dystroglycan; Retinal development; Layering; Basal lamina; Morpholino oligonucleotide; Xenopus expression pattern Abstract: Dystroglycan (DG) is a transmembrane receptor linking the extracellular matrix to the internal cytoskeleton. Its structural function has been mainly characterized in muscle fibers, but DG plays signaling and developmental roles also in different tissues and cell types. We have investigated the effects of dystroglycan depletion during eye development of Xenopus laevis. We have injected a specific morpholino (Mo) antisense oligonucleotide in the animal pole of one dorsal blastomere of embryos at four cells stage. Mo-mediated loss of DG function caused disruption of the basal lamina layers, increased apoptosis and reduction of the expression domains of specific retinal markers, at early stages. Later in development, morphants displayed unilateral ocular malformations, such as microphtalmia and retinal delayering with photoreceptors and ganglion cells scattered throughout the retina or aggregated in rosette-like structures. These results recall the phenotypes observed in specific human diseases and suggest that DG presence is crucial at early stages for the organization of retinal architecture. Author Affiliation: (a) Dipartimento di Fisiologia e Biochimica, Laboratori di Biologia Cellulare e dello Sviluppo, Universita di Pisa, via G. Carducci 13, Ghezzano, Pisa 56010, Italy (b) Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56100 Pisa, Italy Article History: Received 2 March 2005; Revised 5 September 2005; Accepted 30 November 2005

All biomaterials initiate a tissue response when implanted in living tissues. Ultimately this reaction causes fibrous encapsulation and hence isolation of the material, leading to failure of the intended therapeutic effect of the implant. There has been extensive bioengineering research aimed at overcoming or delaying the onset of encapsulation. Nanotechnology has the potential to address this problem by virtue of the ability of some nanomaterials to modulate interactions with cells, thereby inducing specific biological responses to implanted foreign materials. To this effect in the present study, we have characterised the growth of fibroblasts on nano-structured sheets constituted by BaTiO3, a material extensively used in biomedical applications. We found that sheets of vertically aligned BaTiO3 nanotubes inhibit cell cycle progression - without impairing cell viability - of NIH-3T3 fibroblast cells. We postulate that the 3D organization of the material surface acts by increasing the availability of adhesion sites, promoting cell attachment and inhibition of cell proliferation. This finding could be of relevance for biomedical applications designed to prevent or minimize fibrous encasement by uncontrolled proliferation of fibroblastic cells with loss of material-tissue interface underpinning long-term function of implants. [ABSTRACT FROM AUTHOR]

Dystroglycan is a transmembrane receptor protein that provides a structural linkage between extracellular matrix components and cytoskeletal proteins. It was originally characterized as a member of dystrophin associated protein complex in muscle but, unlike other proteins of this complex, mutations in the dystroglycan gene have not been implicated as a cause of muscular dystrophies. Indeed, dystroglycan is an essential gene, expressed early in development that, if removed in knockout mice, provokes lethal defects before the onset of myogenesis. Dystroglycan is synthesized as a precursor propeptide that is post-translationally cleaved and glycosylated to yield alpha and beta subunits. We have cloned and characterized a cDNA clone, containing the complete coding region of the dystroglycan precursor, from a Xenopus laevis cDNA library. We have performed a spatial and temporal analysis of its expression in X. laevis embryos, using whole-mount in situ hybridization and reverse transcription-polymerase chain reaction analysis. Early expression of dystroglycan in a variety of tissues of different embryological derivation suggests a crucial role in morphogenetic events, especially during central nervous system differentiation. [Copyright &y& Elsevier]

Microbiologically induced carbonate precipitation (MICP) is a well-known biogeochemical process that allows the formation of calcium carbonate deposits in the extracellular environment. The high concentration of carbonate and calcium ions on the bacterial surface, which serves as nucleation sites, promotes the calcium carbonate precipitation filling and binding deteriorated materials. Historic buildings and artwork, especially those present in open sites, are susceptible to enhanced weathering resulting from environmental agents, interaction with physical-chemical pollutants, and living organisms, among others. In this work, some published variations of a novel and ecological surface treatment of heritage structures based on MICP are presented and compared. This method has shown to be successful as a restoration, consolidation, and conservation tool for improvement of mechanical properties and prevention of unwanted gas and fluid migration from historical materials. The treatment has revealed best results on porous media matrixes; nevertheless, it can also be applied on soil, marble, concrete, clay, rocks, and limestone. MICP is proposed as a potentially safe and powerful procedure for efficient conservation of worldwide heritage structures. [ABSTRACT FROM AUTHOR]