Reevaluating the function of a transcription factor: MBF-1 as a sea urchin chromatin organizer ?

The Zinc-finger MBF-1 factor is involved in the expression of the early histone genes during devel-opment of the sea urchin embryo (1, 2). In spite of being a transcription activator, the DNA-binding domain of MBF-1 shares high sequence similarity with that of the chromatin organizer CTCF of vertebrates and drosophila (3). On the other hand, extensive in silico analysis failed to identify the sea urchin CTCF ortholog (4). This led us to speculate that MBF-1 somehow could have co-opted the function of CTCF during evolution of the echinoderms. Since in vertebrates CTCF binds Hox chromatin, to support our hypothesis, we first identified high-score putative binding sequences for CTCF/MBF-1 within the single sea urchin Hox gene cluster. Moreover, we observed the full evolu-tionary conservation of these binding sites in S. purpuratus and P. lividus species. Worth of men-tion, by chromatin immunoprecipitation (ChIP) assay, we detected the occupancy of MBF-1 on hox11/13-a, -b, and -c regulatory sequences at distinct stages of development. As expected from the binding of an activator, we found that the association of MBF-1 to the cis-regulatory sequences of both hox11/13-a and -b genes relates to the transcriptional status of these genes. Strikingly, we also mapped the physical binding of MBF-1 to hox11/13-c, which is instead not expressed during em-bryogenesis. Altogether, these observations indeed suggest the possibility that MBF-1, besides be-ing a transcription activator, could also function as a general chromatin organizer. To further support this hypothesis, we are planning ChIP-seq experiments to identify the association of MBF-1 to the sea urchin chromatin at a genome-wide level. 1. Di Caro, V. et al. (2007) J. Mol. Bio.,365, 1285-97. 2. Cavalieri,V et al. (2009) Nucleic Acid Res, 37,7407-7415. 3. Heger , P. et al. (2012) PNAS, 109, 17507\u201317512. 4. Cavalieri, V. et al. (2013) Plos Genetics, 9, e1003847

Composition and geographic variation of the bacterial microbiota associated with the coelomic fluid of the sea urchin Paracentrotus lividus

In the present work, culture-based and culture-independent investigations were performed to determine the microbiota structure of the coelomic fluid of Mediterranean sea urchin Paracentrotus lividus individuals collected from two distinct geographical sites neighboring a high-density population bay and a nature reserve, respectively. Next Generation Sequencing analysis of 16S rRNA gene (rDNA) showed that members of the Proteobacteria, Bacteroidetes and Fusobacteria phyla, which have been previously reported to be commonly retrieved from marine invertebrates, dominate the overall population of microorganisms colonizing this liquid tissue, with minority bacterial genera exhibiting remarkable differences among individuals. Our results showed that there is a correlation between microbiota structure and geographical location of the echinoderm collection site, highlighting over-representation of metagenomic functions related to amino acid and bioactive peptides metabolism in specimens inhabiting the nature reserve. Finally, we also described the developmental delay and aberrations exhibited by sea urchin embryos exposed to distinct bacterial isolates, and showed that these defects rely upon hydrophilic compound(s) synthesized by the bacterial strains assayed. Altogether, our findings lay the groundwork to decipher the relationships of bacteria with sea urchins in their aquatic environment, also providing an additional layer of information to understand the biological roles of the coelomic fluid

On the Use of Darcy Permeability in Sheared Fabrics

Determination of a set of processing parameters for a given material type is a complex process, and much work has been done using the framework developed in the last century by Darcy. While this model, assuming Newtonian flow through a granular (essentially a smoothed, porous) medium, has produced useful flow front progression simulation tools, a commonly arising problem in the fabrication of complex components is the modeling of flow front through regions of locally high shear. Several current approaches stem from a modification of the Darcy description using "local" permeabilities for these regions, differing from the permeabilities experimentally obtained in the unsheared or undeformed state. The work presented here investigates the applicability of a transformation of the permeability in the unsheared state, and conjectures that the driving forces for the fluid flow may be sufficiently complex to merit more detailed constitutive modeling in complex fabric architectures. Experiments on sheared fabrics have been performed, and permeabilities are compared with those obtained by tensor-transformation of unsheared fabric permeabilities.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68427/2/10.1177_073168449901800507.pd

AISF position paper on liver transplantation and pregnancy. Women in Hepatology Group, Italian Association for the Study of the Liver (AISF)

After the first successful pregnancy in a liver transplant recipient in 1978, much evidence has accumulated on the course, outcomes and management strategies of pregnancy following liver transplantation. Generally, liver transplantation restores sexual function and fertility as early as a few months after transplant. Considering that one third of all liver transplant recipients are women, that approximately one-third of them are of reproductive age (18-49 years), and that 15% of female liver transplant recipients are paediatric patients who have a >70% probability of reaching reproductive age, the issue of pregnancy after liver transplantation is rather relevant, and obstetricians, paediatricians, and transplant hepatologists ever more frequently encounter such patients. Pregnancy outcomes for both the mother and infant in liver transplant recipients are generally good, but there is an increased incidence of preterm delivery, hypertension/preeclampsia, foetal growth restriction, and gestational diabetes, which, by definition, render pregnancy in liver transplant recipients a high-risk one. In contrast, the risk of congenital anomalies and the live birth rate are comparable to those of the general population. Currently there are still no robust guidelines on the management of pregnancies after liver transplantation. The aim of this position paper is to review the available evidence on pregnancy in liver transplant recipients and to provide national Italian recommendations for clinicians caring for these patients