The effect of Cyclosporine A on cardiomyocytes differentiation

Cyclosporine A (CsA) is a powerful immunosuppressive drug which significantly improved the success of organ transplantation; however, the major limiting factors for the drug's clinical use are its long and short term adverse effects. The present study was conducted to examine, in a dose-dependent manner, in a model of cardiogenesis, the effect of CsA on cardiomyocytes differentiation.     

The peptaibol alamethicin induces an rRNA-cleavage-associated death in Arabidopsis thaliana

The plant-metabolic response to amphipathic peptides produced by the soil fungi of the genus Trichoderma remains largely unknown. The present investigation was undertaken to examine the death process in alamethicin-treated Arabidopsis thaliana plantlets. The rapid death triggered by alamethicin (at 50 microM) was shown to be associated with protein-synthesis arrest and with specific cleavage of 18S and 25S ribosomal RNA. The use of an inhibitor of nitric oxide (NO) synthases and of an NO scavenger suggested that rRNA cleavage was suppressed by NO. Experiments conducted with a synthetic alamethicin analogue, in which all alpha-aminoisobutyric acid (Aib) residues have been replaced by leucine moieties, showed that the non-coded residues are essential for the ability of the peptaibol to induce rRNA cleavage in Arabidopsis. Our data indicate that further investigations on the mode of action of alamethicin in planta could be of great interest to study the death-signaling pathway associated with rRNA degradation in plants.     

Proteome analysis of Rickettsia felis highlights the expression profile of intracellular bacteria

The proteome of Rickettsia felis, an obligate intracellular bacterium responsible for spotted fever, was analyzed using two complementary proteomic approaches: 2-DE coupled with MALDI-TOF, and SDS-PAGE with nanoLC-MS/MS. This strategy allowed identification of 165 proteins and helped to answer some questions raised by the genome sequence of this bacterium. We successfully identified potential virulence factors including two putative adhesins, four proteins of the type IV secretion system, four Sca autotransporters, four components of ABC transporters, some R. felis-specific proteins, and one antitoxin of the toxin-antitoxin system. Notably, the antitoxin was the first to be identified in intracellular bacteria. Only one protein containing rickettsia palindromic repeats was found, whereas none of the split genes, transposases, or tetratricopeptide/ankyrin repeats were detectably expressed. Comparison of the protein expression profiles of R. felis and 23 other bacterial species according to functional categories showed that intracellular bacteria express more proteins related to translation, especially ribosomal proteins. However, the remaining bacteria express more proteins related to energy production and carbohydrate/amino acid metabolism. In conclusion, this study reveals R. felis virulence factor expression and highlights the unique protein expression profile of intracellular bacteria.     

Promoting proteomics knowledge in Europe: report on the activities of the EuPA Education Committee 2006-2007

The early transition of knowledge from highly specialised and sophisticated proteomics research to a diverse community in need of know-how is a challenge that requires backing from advanced research centres and groups, and a coordinating body for the dissemination of this knowledge. The European Proteomics Association (EuPA) Education Committee signified this as a priority area when the EuPA was formed, and began its program to coordinate proteomics training and knowledge dissemination in 2006. This report serves as an update of our past activities and an announcement of upcoming events. Over the last year the EuPA Education Committee has coordinated or supported different educational activities including basic and advanced courses, a summer school, workshops and tutorials. A new programme of basic courses dubbed "Teaching the Teachers" has been initiated. These courses reach a larger, Europe wide, audience in a short timeframe, thus improving the opportunities for trainees of elementary proteomics techniques. Another important event has been the merger of the EuPA and HUPO (Human Proteome Organisation) Education Committees into a single one in order to combine ideas and ef for ts that will favour global education in proteomics.     

Differential expression of sarcoplasmic proteins in four heterogeneous ovine skeletal muscles

Fiber-type distribution is known to vary widely within and between muscles according to differences in muscle functions. 2-DE and MALDI-MS were used to investigate the molecular basis of muscle fiber type-related variability. We compared four lamb skeletal muscles with heterogeneous fiber-type composition that are relatively rich in fast-twitch fiber types, i.e., the semimembranosus, vastus medialis, longissimus dorsi, and tensor fasciae latae (TL). Our results clearly showed that none of the glycolytic metabolism enzymes detected, including TL which was most strongly glycolytic, made intermuscular differentiation possible. Muscle differentiation was based on the differential expression of proteins involved in oxidative metabolism, including not only citric acid cycle enzymes but also other classes of proteins with functions related to oxidative metabolism, oxidative stress, and probably to higher protein turnover. Detected proteins were involved in transport (carbonate dehydratase, myoglobin, fatty acid-binding protein), repair of misfolding damage (heat shock protein (HSP) 60 kDa, HSP-27 kDa, alpha-crystallin beta subunit, DJ1, stress-induced phosphoprotein), detoxification or degradation of impaired proteins (GST-Pi, aldehyde dehydrogenase, peroxiredoxin, ubiquitin), and protein synthesis (tRNA-synthetase). The fractionating method led to the detection of proteins involved in different functions related to oxidative metabolism that have not previously been shown concomitancy.     

Mrc1, a non-essential DNA replication protein,is required for telomere end protection following loss of capping by Cdc13, Yku or telomerase

Proteins involved in telomere end protection have previously been identified. In Saccharomyces cerevisiae, Cdc13, Yku and telomerase, mainly, prevent telomere uncapping, thus providing telomere stability and avoiding degradation and death by senescence. Here, we report that in the absence of Mrc1, a component of the replication forks, telomeres of cdc13 or yku70 mutants exhibited increased degradation, while telomerase-negative cells displayed accelerated senescence. Moreover, deletion of MRC1 increased the single-strandedness of the telomeres in cdc13-1 and yku70Δ mutant strains. An mrc1 deletion strain also exhibited slight but stable telomere shortening compared to a wild-type strain. Loss of Mrc1’s checkpoint function alone did not provoke synthetic growth defects in combination with the cdc13-1 mutation. Combinations between the cdc13-1 mutation and deletion of either TOF1 or PSY2, coding for proteins physically interacting with Mrc1, also resulted in a synthetic growth defect. Thus, the present data suggest that non-essential components of the DNA replication machinery, such as Mrc1 and Tof1, may have a role in telomere stability in addition to their role in fork progression.     

Hsp90 selectively modulates phenotype in vertebrate development

Compromised heat shock protein 90 (Hsp90) function reveals cryptic phenotypes in flies and plants. These observations were interpreted to suggest that this molecular stress-response chaperone has a capacity to buffer underlying genetic variation. Conversely, the protective role of Hsp90 could account for the variable penetrance or severity of some heritable developmental malformations in vertebrates. Using zebrafish as a model, we defined Hsp90 inhibitor levels that did not induce a heat shock response or perturb phenotype in wild-type strains. Under these conditions the severity of the recessive eye phenotype in sunrise, caused by a pax6b mutation, was increased, while in dreumes, caused by a sufu mutation, it was decreased. In another strain, a previously unobserved spectrum of severe structural eye malformations, reminiscent of anophthalmia, microphthalmia, and nanophthalmia complex in humans, was uncovered by this limited inhibition of Hsp90 function. Inbreeding of offspring from selected unaffected carrier parents led to significantly elevated malformation frequencies and revealed the oligogenic nature of this phenotype. Unlike in Drosophila, Hsp90 inhibition can decrease developmental stability in zebrafish, as indicated by increased asymmetric presentation of anophthalmia, microphthalmia, and nanophthalmia and sunrise phenotypes. Analysis of the sunrise pax6b mutation suggests a molecular mechanism for the buffering of mutations by Hsp90. The zebrafish studies imply that mild perturbation of Hsp90 function at critical developmental stages may underpin the variable penetrance and expressivity of many developmental anomalies where the interaction between genotype and environment plays a major role.     

Characterization of the Physical State of Spray-Dried Inulin

Modulated differential scanning calorimetry, wide angle x-ray scattering, and environmental scanning electron microscopy were used to investigate the physical and morphological properties of chicory root inulin spray dried under different conditions. When the feed temperature increased up to 80 °C, the average degree of polymerization of the solubilized fraction increased, leading to a higher glass transition temperature (Tg). Above 80 °C, the samples were completely amorphous, and the Tg did not change. The starting material was semicrystalline, and the melting region was composed of a dual endotherm; the first peak subsided as the feed temperature increased up to a temperature of 70 °C, whereas above 80 °C, no melting peak was observed as the samples were completely amorphous. To a lesser extent, the inlet air temperature of 230 °C allowed a higher amorphous content of the samples than at 120–170 °C but induced a blow-out of the particles.     

Characterization of natural hybrids of Saccharomyces cerevisiae and Saccharomyces bayanus var. uvarum

Nine yeast strains were isolated from spontaneous fermentations in the Alsace area of France, during the 1997, 1998 and 1999 grape harvests. Strains were characterized by pulsed-field gel electrophoresis, PCR-restriction fragment length polymorphism (RFLP) of the MET2 gene, delta-PCR, and microsatellite patterns. Karyotypes and MET2 fragments of the nine strains corresponded to mixed chromosomal bands and restriction patterns for both Saccharomyces cerevisiae and Saccharomyces bayanus var. uvarum. They also responded positively to amplification with microsatellite primers specific to both species and were demonstrated to be diploid. However, meiosis led to absolute nonviability of their spores on complete medium. All the results demonstrated that the nine yeast strains isolated were S. cerevisiaexS. bayanus var. uvarum diploid hybrids. Moreover, microsatellite DNA analysis identified strains isolated in the same cellar as potential parents belonging to S. bayanus var. uvarum and S. cerevisiae.