T cell receptor alpha gene rearrangement and transcription in adult thymic gamma delta cells.

T cells belong to two separate lineages based on surface expression of alpha beta or gamma delta T cell receptors (TCR). Since during thymus development TCR beta, gamma, and delta genes rearrange before alpha genes, and gamma delta cells appear earlier than alpha beta cells, it has been assumed that gamma delta cells are devoid of TCR alpha rearrangements. We show here that this is not the case, since mature adult, but not fetal, thymic gamma delta cells undergo VJ alpha rearrangements more frequently than immature alpha beta lineage thymic precursors. Sequence analysis shows VJ alpha rearrangements in gamma delta cells to be mostly (70%) nonproductive. Furthermore, VJ alpha rearrangements in gamma delta cells are transcribed normally and, as shown by analysis of TCR beta-/- mice, occur independently of productive VDJ beta rearrangements. These data are interpreted in the context of a model in which precursors of alpha beta and gamma delta cells differ in their ability to express a functional pre-TCR complex.

Activation of PPAR delta Regulates Ywhae (Encoding 14-3-3 epsilon Protein), a Gene Required for Ventricular Morphogenesis

Cardiac ventricular morphogenesis is a key developmental stage during which the ventricles grow considerably in size, but the transcriptional pathways controlling this process remains poorly understood. 14-3-3_ is a member of a conserved protein family that regulates a wide range of processes such as transcription, apoptosis and proliferation by binding to the phospho-serine/threonine residues of its target proteins. We found that deletion of the Ywhae gene (encoding 14-3-3_) in mice leads to abnormal ventricular morphogenesis and an embryonic cardiomyopathy (Cieslik KA et al, Circ. Res. 2008, abstract). Interestingly, we recently showed in cultured cells that the Ywhae gene is regulated directly by peroxisome proliferator-activated receptor _ (PPAR_) (Brunelli L et al, Circ. Res. 2007), a ligand-inducible nuclear receptor that controls energy metabolism and development. Postnatal cardiac-specific deletion of the Ppard gene in mice causes a lethal dilated cardiomyopathy, but it is still unknown whether PPAR_ regulates genes involved in heart development. We hypothesized that the expression of the Ywhae gene is responsive to PPAR_ during heart development. We confirmed that PPAR_ is expressed in the heart during development, and found higher expression at E10.5 compared to later gestational ages. We showed by immunofluorescence that a PPAR_ agonist (50 _M L-165,041 for 24 hr) upregulates 14-3-3_ in primary cardiomyocytes. We showed that when P19CL6 cells are driven towards cardiomyocyte lineage by dimethyl sulfoxide (DMSO), 14-3-3_ levels increase 4-fold, while L-165,041 treatment increases levels by an additional 50%. Based on previous work in mice (Leibowitz MD et al, FEBS Lett. 2000; Letavernier E et al, J. Am. Soc. Nephrol. 2005), we tested the response of Ywhae to PPAR_ in vivo . We fed 30 mg/kg/day L-165,041 to 14-3-3__/_ adult pregnant mice for 3 days starting at E9.5 and assessed Ywhae mRNA levels in embryonic hearts at E12.5. Baseline mRNA levels in Ywhae_/_ hearts were double that of Ywhae_/ hearts, while L-165,041 upregulated Ywhae mRNA levels in both Ywhae_/_ and Ywhae_/ hearts by 65%. These results indicate that Ywhae responds to PPAR_ in vivo, and suggest that PPAR_ regulates Ywhae during ventricular morphogenesis.

Algunos Briozos del Cuaternario del Delta del río Llobregat (Barcelona)

Se estudian algunas formas de Briozoos del Cuaternario del delta del Llobregat (tocando a la ciudad de Barcelona). Se reconocen dos especies del gnero Cellaria, una Discoporella, una Cupztladria y una Porclla. Adems de una discusin sistemtica sobre el gnero Cellaria y Porclla se dan datos micromtricos abundantes y se establecen comparaciones con los dados por otros autores insinundose algunas conclusiones.

Análisis litosísmico y estructura sedimentaria de la plataforma interna al Norte del delta del Ebro (sector de Vandellós)

El análisis sísmico de perfiles de alta resolución del tipo ((uniboom)), realizados en la plataforma interna al N del Delta del Ebro, permite definir las unidades sísmicas y establecer la estructura sedimentaria del Ambos aspectos reflejan la influencia diferencial de los procesos recubrimiento cuaternario medio/superior. Ambos aspectos reflejan la influencia diferencial de los procesos dinámicos y de las oscilaciones eustáticas.

Sedimentos prodeltaicos en el Delta emergido del Llobregat

La unidad de limos intermedios del delta del Llobregat corresponde a un ambiente prodeltaico en el que se han identificado, por comparación al modelo actual, subambientes de prodelta proximal, medio y medio-distal. Su agua intersticial es sinsedimentaria, hallándose en la actualidad parcialmente diluida.

Delta(1232) isobar excitations in nuclear many-body systems from varios NN interactions.

Delta isobar components in the nuclear many-body wave function are investigated for the deuteron, light nuclei (16O), and infinite nuclear matter within the framework of the coupled-cluster theory. The predictions derived for various realistic models of the baryon-baryon interaction are compared to each other. These include local (V28) and nonlocal meson exchange potentials (Bonn2000) but also a model recently derived by the Salamanca group accounting for quark degrees of freedom. The characteristic differences which are obtained for the NDelta and Delta Delta correlation functions are related to the approximation made in deriving the matrix elements for the baryon-baryon interaction.

Delta(1232) isobar excitations and the ground state of nuclei

The influence of Delta isobar components on the ground-state properties of nuclear systems is investigated for nuclear matter as well as finite nuclei. Many-body wave functions, including isobar configurations and binding energies, are evaluated employing the framework of the coupled-cluster theory. It is demonstrated that the effect of isobar configurations depends in a rather sensitive way on the model used for the baryon-baryon interaction. As examples for realistic baryon-baryon interactions with explicit inclusion of isobar channels we use the local (V28) and nonlocal meson-exchange potentials (Bonn2000) but also a model recently developed by the Salamanca group, which is based on a quark picture. The differences obtained for the nuclear observables are related to the treatment of the interaction, the pi-exchange contributions in particular, at high momentum transfers.

PPARbeta/delta regulates paneth cell differentiation via controlling the hedgehog signaling pathway.

BACKGROUND & AIMS: All 4 differentiated epithelial cell types found in the intestinal epithelium derive from the intestinal epithelial stem cells present in the crypt unit, in a process whose molecular clues are intensely scrutinized. Peroxisome proliferator-activated receptor beta (PPARbeta) is a nuclear hormone receptor activated by fatty acids and is highly expressed in the digestive tract. However, its function in intestinal epithelium homeostasis is understood poorly. METHODS: To assess the role of PPARbeta in the small intestinal epithelium, we combined various cellular and molecular approaches in wild-type and PPARbeta-mutant mice. RESULTS: We show that the expression of PPARbeta is particularly remarkable at the bottom of the crypt of the small intestine where Paneth cells reside. These cells, which have an important role in the innate immunity, are strikingly affected in PPARbeta-null mice. We then show that Indian hedgehog (Ihh) is a signal sent by mature Paneth cells to their precursors, negatively regulating their differentiation. Importantly, PPARbeta acts on Paneth cell homeostasis by down-regulating the expression of Ihh, an effect that can be mimicked by cyclopamine, a known inhibitor of the hedgehog signaling pathway. CONCLUSIONS: We unraveled the Ihh-dependent regulatory loop that controls mature Paneth cell homeostasis and its modulation by PPARbeta. PPARbeta currently is being assessed as a drug target for metabolic diseases; these results reveal some important clues with respect to the signals controlling epithelial cell fate in the small intestine.

The nuclear hormone receptor peroxisome proliferator-activated receptor beta/delta potentiates cell chemotactism, polarization, and migration.

After an injury, keratinocytes acquire the plasticity necessary for the reepithelialization of the wound. Here, we identify a novel pathway by which a nuclear hormone receptor, until now better known for its metabolic functions, potentiates cell migration. We show that peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) enhances two phosphatidylinositol 3-kinase-dependent pathways, namely, the Akt and the Rho-GTPase pathways. This PPARbeta/delta activity amplifies the response of keratinocytes to a chemotactic signal, promotes integrin recycling and remodeling of the actin cytoskeleton, and thereby favors cell migration. Using three-dimensional wound reconstructions, we demonstrate that these defects have a strong impact on in vivo skin healing, since PPARbeta/delta-/- mice show an unexpected and rare epithelialization phenotype. Our findings demonstrate that nuclear hormone receptors not only regulate intercellular communication at the organism level but also participate in cell responses to a chemotactic signal. The implications of our findings may be far-reaching, considering that the mechanisms described here are important in many physiological and pathological situations.

Critical roles of PPAR beta/delta in keratinocyte response to inflammation.

The immediate response to skin injury is the release of inflammatory signals. It is shown here, by use of cultures of primary keratinocytes from wild-type and PPAR beta/delta(-/-) mice, that such signals including TNF-alpha and IFN-gamma, induce keratinocyte differentiation. This cytokine-dependent cell differentiation pathway requires up-regulation of the PPAR beta/delta gene via the stress-associated kinase cascade, which targets an AP-1 site in the PPAR beta/delta promoter. In addition, the pro-inflammatory cytokines also initiate the production of endogenous PPAR beta/delta ligands, which are essential for PPAR beta/delta activation and action. Activated PPAR beta/delta regulates the expression of genes associated with apoptosis resulting in an increased resistance of cultured keratinocytes to cell death. This effect is also observed in vivo during wound healing after an injury, as shown in dorsal skin of PPAR beta/delta(+/+) and PPAR beta/delta(+/-) mice.