Gene structure and promoter analysis of the human GJB6 gene encoding connexin 30

Connexins (Cx) are the protein subunits of gap junctions, which play an important role in cell-to-cell communication. We characterized the genomic structure of the human GJB6 gene, encoding connexin 30 (C x 30), and showed that it differs from most connexin-encoding genes. GJB6 presents six different exons, some of which can be alternatively spliced. We also mapped a basal promoter sequence active in a human keratinocyte cell line which responds to the activation of the EGF receptor. One of the non-encoding exons of GJB6, which has been described in brain C x 30 cDNA, was not found in cDNA obtained from human keratinocytes, suggesting tissue-specific splicing.     

Amyloidosis: a model of misfolded protein disorder

Amyloidosis bears many characteristics of orphan diseases. Its diagnosis is difficult and often delayed. The main reasons thereof are its quite various clinical presentation: amyloidosis behaves as a new great masquerader, and the need to get a tissue sample to submit to specific dyes. Although we have been able for a long time to recognize amyloid, its intimate nature has remained quite completely enigmatic until recently. In fact, major advances in this way have appeared only in the last decade and it is now possible to consider the mechanisms of amyloidosis as a multistep phenomenon. Amyloidosis is no more thought only as a < storage disease > of the extracellular space. This archaic viewpoint has shifted to the emerging paradigm of misfolded protein disorders. Amyloid proteins thus appear as a subgroup of misfolded proteins, where misfolding leads to subsequent aggregation. This aggregation may be a generic property of polypeptide chains possibly linked to their common peptide backbone that does not depend on specific amino acid sequences. And, in fact, many proteins can in vitro form amyloid-like aggregates, while in vivo, only 20 amyloid proteins have been so far identified. Although misfolding and aggregation are quite well studied in vitro, the last step of amyloid deposition, i.e. anchorage to the extracellular matrix, can not be so easily approached. Proteoglycans and serum amyloid P component have nevertheless been identified as key elements involved in extracellular deposition of amyloid proteins. These advances have opened new avenues in the therapeutic of amyloid disorders. Current treatment consists of support or replacement of impaired organ function and measures to reduce the production of amyloidogenic precursor proteins. Potential novel therapeutic strategies include stabilisation of the native fold of precursor proteins with targeted small molecules, reversion of misfolded proteins to their native state with < beta-sheet breakers >, inhibition of amyloid fibril propagation and enhancement of amyloid clearance either through immunotherapy or by reducing the stability of deposits through depletion of serum amyloid P component, and breaking the anchorage to the extracellular matrix with glycosaminoglycan analogs.     

Structural and functional analysis of the C-terminal STAS (sulfate transporter and anti-sigma antagonist) domain of the Arabidopsis thaliana sulfate transporter SULTR1.2

The C-terminal region of sulfate transporters from plants and animals belonging to the SLC26 family members shares a weak but significant similarity with the Bacillus sp. anti-anti-sigma protein SpoIIAA, thus defining the STAS domain (sulfate transporter and anti-sigma antagonist). The present study is a structure/function analysis of the STAS domain of SULTR1.2, an Arabidopsis thaliana sulfate transporter. A three-dimensional model of the SULTR1.2 STAS domain was built which indicated that it shares the SpoIIAA folds. Moreover, the phosphorylation site, which is necessary for SpoIIAA activity, is conserved in the SULTR1.2 STAS domain. The model was used to direct mutagenesis studies using a yeast mutant defective for sulfate transport. Truncation of the whole SULTR1.2 STAS domain resulted in the loss of sulfate transport function. Analyses of small deletions and mutations showed that the C-terminal tail of the SULTR1.2 STAS domain and particularly two cysteine residues plays an important role in sulfate transport by SULTR1.2. All the substitutions made at the putative phosphorylation site Thr-587 led to a complete loss of the sulfate transport function of SULTR1.2. The reduction or suppression of sulfate transport of the SULTR1.2 mutants in yeast was not due to an incorrect targeting to the plasma membrane. Both our three-dimensional modeling and mutational analyses strengthen the hypothesis that the SULTR1.2 STAS domain is involved in protein-protein interactions that could control sulfate transport.     

Professions, generations and reproductive dynamics of a French Alpine population (16th-20th centuries)

As part of a survey of the biological history of Alpine populations, the lineages of all the families of the Vallouise valley (a French 'department' of the Hautes Alpes) have been reconstructed over several centuries. The genealogies have been included in a computerized population record, known as 'Vallouise in the Brian?on area (14th-20th centuries)', using the French-Canadian programme Analypop. Most of the professions of the family heads were included in the files. In this study, various profession groups were identified and their descents determined over successive generations. In this mountain area, where over 92% of marriages took place among relatives during the 19th century, the profession groups modulated their descents according to chosen strategies, sometimes with considerable differences among groups but with a remarkable consistency of behaviour. Moreover, there was weak interpenetration in the descents of each profession at both the 2nd and 3rd generations.     

FIGENIX: Intelligent automation of genomic annotation: expertise integration in a new software platform

Background  

Two of the main objectives of the genomic and post-genomic era are to structurally and functionally annotate genomes which consists of detecting genes' position and structure, and inferring their function (as well as of other features of genomes). Structural and functional annotation both require the complex chaining of numerous different software, algorithms and methods under the supervision of a biologist. The automation of these pipelines is necessary to manage huge amounts of data released by sequencing projects. Several pipelines already automate some of these complex chaining but still necessitate an important contribution of biologists for supervising and controlling the results at various steps.     

Synthesis and study of conformationally restricted 3'-deoxy-3',4'-exo-methylene nucleoside analogues

Hitherto unknown restricted 3'-deoxy-3',4'-exo-methylene nucleoside derivatives bearing the nucleic acid naturally occurring pyrimidine bases have been synthesized. The compounds were tested for their activity against HIV, HBV, and several RNA viruses, but they did not show significant antiviral effect.     

Salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from Trichoderma longibrachiatum

Infiltration of cellulase (EC 3.2.1.4) from Trichoderma longibrachiatum into melon (Cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. An oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (SA) signaling pathways leading to marked induction of peroxidase and chitinase activities. The treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase and chitinase activities, but the oxidative burst and SA production were not observed. Co-infiltration of aminoethoxyvinil-glycine (an ethylene inhibitor) with the active cellulase did not affect the high increase of peroxidase and chitinase activities. In contrast, co-infiltration of aminoethoxyvinil-glycine with the denatured enzyme blocked peroxidase and chitinase activities. Our data suggest that the SA pathway (induced by the cellulase activity) and ethylene pathway (induced by heat-denatured and active protein) together coordinate the activation of defense mechanisms. We found a partial interaction between both signaling pathways since SA caused an inhibition of the ethylene production and a decrease in peroxidase activity when co-infiltrated with denatured cellulase. Treatments with active or denatured cellulase caused a reduction in powdery mildew (Sphaerotheca fuliginea) disease.     

3D realtime echography and echography assisted by a robotic arm for investigating astronauts in the ISS from the ground

As human will stay for long duration in isolated sites like ISS there will be a need to perform quick and reliable diagnosis to evaluate the gravity of the pathology in presence of clinical symptoms. Many pathological situations (abnormal heart rate, pericardic collection, mitral prolaps, cholecystis, renal lithiasis, normal and ectopic pregnancies, ovarian cyst, acute appendicitis, phlebitis ... ) may occur even if all the astronauts are absolutely normal and healthy preflight. Ultrasound echography and Doppler are non invasive methods easy to use in space and very well adapted and used in routine for such diagnosis at the hospital. The objective of the present project was to design a method that guarantee a reliable echographic diagnostic in an isolated site (space station or earth site) by a Medical Doctor located at the expert site that should be the Nasa control center for ISS. It is supposed that there is only a non sonographer person in the isolated site and that the transmission system (audio, video, numeric..) is the only link between the 2 sites. Two options are proposed: (a) A 3D realtime acquisition echograph that can record quickly all the echos of a volume containing the organ suspected to have a lesion, all these echo information being sent to the ground and processed by the ground experts, (b) A robotic arm that hangs the echo probe in the isolated site tele-operated (through sattelite network) from the ground by an expert in clinical ultrasound. (As the expert moves the joystick of his ground computer the robotic arm reproduces the same movements on the probe).     

Changes in major intracellular osmolytes in L-929 cells following rapid and slow application of hyperosmotic media

Cultured L-929 cells respond to media-made hyperosmotic (600 mOsmol/kg H2O) by addition of NaCl, sorbitol or proline by adjusting successively their intracellular level in different osmolytes: Na+, K+, amino acids and sorbitol. In the NaCl medium, Na+ and K+ are first to increase. Their concentration is then down-regulated while they are replaced by less disrupting osmolytes: amino acids and sorbitol. The amino-acid level is also adjusted with respect to the increase in sorbitol which starts only after 24 h, depending on the induction of aldose reductase. A similar evolution in the amount of these osmolytes is observed, with different time scales and amplitudes, depending on whether the osmotic shocks are applied abruptly or slowly, in a more physiological way. The interplay between the osmolytes is also different depending on their availability in the external medium. Such complex evolutions indicate that a cascade of interacting signals must be considered to account for the overall regulation process. It can hardly be fitted into a model implicating a single primary signalling event (early increase in ions or decrease in cell volume) as usually postulated. Also, the volume up-regulation is not significantly different in the different conditions, showing that it is not primarily dependent on the adjustment of the intracellular osmolarity which is reached immediately upon cell shrinkage and is maintained all over, independently of the availability and changes in nature of the osmolytes.