Biological Rhythms in the Skin

Circadian rhythms, ≈24 h oscillations in behavior and physiology, are reflected in all cells of the body and function to optimize cellular functions and meet environmental challenges associated with the solar day. This multi-oscillatory network is entrained by the master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, which directs an organism’s rhythmic expression of physiological functions and behavior via a hierarchical system. This system has been highly conserved throughout evolution and uses transcriptional–translational autoregulatory loops. This master clock, following environmental cues, regulates an organism’s sleep pattern, body temperature, cardiac activity and blood pressure, hormone secretion, oxygen consumption and metabolic rate. Mammalian peripheral clocks and clock gene expression have recently been discovered and are present in all nucleated cells in our body. Like other essential organ of the body, the skin also has cycles that are informed by this master regulator. In addition, skin cells have peripheral clocks that can function autonomously. First described in 2000 for skin, this review summarizes some important aspects of a rapidly growing body of research in circadian and ultradian (an oscillation that repeats multiple times during a 24 h period) cutaneous rhythms, including clock mechanisms, functional manifestations, and stimuli that entrain or disrupt normal cycling. Some specific relationships between disrupted clock signaling and consequences to skin health are discussed in more depth in the other invited articles in this IJMS issue on Sleep, Circadian Rhythm and Skin

L’évolution des premières de couverture des romans d’horreur de Stephen King : Analyse à travers Carrie, The Shining, Misery et Pet Semetary et leurs adaptations au cinéma

Mémoire de Master 2 Cultures de l\u27écrit et de l\u27image traitant de l\u27importance de la première de couverture comme première présentation d\u27un livre. Pour cela il s\u27appuie sur l\u27exemple de quatre romans de Stephen King

Les différentes manières de raconter le fait-divers au XIXème siècle à travers le cas du crime de Pantin

Mémoire de recherche de M1 Cultures de l\u27écrit et de l\u27image traitant de la naissance des journaux spécialisés en faits-divers à travers d\u27une étude de cas

Proteomic analysis to understand Cr(VI) homeostasis in Streptomyces sp. MC1

Chromium is a heavy metal widely used in a variety of industrial processes (leather tanning, steel production, metal corrosion inhibition). Hexavalent chromium is carcinogenic and presents higher toxicity than trivalent form since Cr(VI) is more water-soluble and mobile than Cr(III). Industrial effluents containing Cr(VI) are released into water courses, mostly without proper treatment, resulting in anthropogenic contamination. Over the last years, bacteria-mediated removal or stabilization of heavy metal into no or less toxic forms has become in an effective biotechnological process. In this sense, several physiological studies on Streptomyces sp. MC1, an actinobacteria isolated from a polluted soil in the province of Tucumán (Argentina), demonstrated be able to grow in presence of Cr(VI) and remove the metal both in liquid medium and contaminated soils. However, the molecular mechanisms involved are unknown in this actinobacteria. MS-based proteomics have become a powerful tool to understand the mechanisms that underlie physiological processes. In the present work, we use MS-based, label-free and quantitative proteomic analyses in order to identify enzymes involves in oxidative stress response caused by the presence of Cr(VI) in our actinobacteria strain MC1. Sampling points for proteomics analyses were established according to the growth of Streptomyces sp. MC1 in minimal medium (MM) amended with Cr(VI) at 50 mg L-1 and MM without the metal (control condition). Cells were harvested after 18 and 24 h of incubation in control condition and MM with Cr(VI) respectively. These sampling points allowed obtaining comparable and metabolically active cells (exponential phase of growth). Cr(VI) removal was 10% at the time that cells were harvested (24 h). A total of 1981 different proteins were detected in the proteome. It represents approximately 22% of the predicted protein sequences for this strain. 518 of these proteins passed our significance parameters which 186 of them were up-regulated in the condition supplemented with Cr(VI). Analysis with the software BlastKOALA showed that up-regulated proteins were distributed in metabolic pathways that result essential for a correct cellular operation. Overall, the proteins were related to carbon and energy metabolism, genetic information processing, oxidative stress response and membrane transports. Interestingly, enzymes from pentose phosphate pathway increasing significantly their abundance in presence of chromium. About, 10 different oxidoreductases enzymes were up-regulated in presence of the metal. Regarding oxidative stress response, key enzymes like superoxide dismutase, catalase, mycothiol synthase, and mycothiol amidase were identified with an increment in their abundance. The proteome analysis performed in Streptomyces sp. MC1 allowed us to identify the proteins involves in the homeostasis of Cr(VI). These results serve as basement to study and improve the heavy metal removal by actinobacteria.Fil: Sineli, Pedro Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Aparicio, Juan Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pernodet, Jean Luc. Institut de Biologie Intégrative de la Cellule; FranciaFil: Polti, Marta Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaLV Annual SAIB Meeting and XIV PABMB CongressSaltaArgentinaSociedad Argentina de Investigaciones Bioquímica

Porous Bead-Based Diagnostic Platforms: Bridging the Gaps in Healthcare

Advances in lab-on-a-chip systems have strong potential for multiplexed detection of a wide range of analytes with reduced sample and reagent volume; lower costs and shorter analysis times. The completion of high-fidelity multiplexed and multiclass assays remains a challenge for the medical microdevice field; as it struggles to achieve and expand upon at the point-of-care the quality of results that are achieved now routinely in remote laboratory settings. This review article serves to explore for the first time the key intersection of multiplexed bead-based detection systems with integrated microfluidic structures alongside porous capture elements together with biomarker validation studies. These strategically important elements are evaluated here in the context of platform generation as suitable for near-patient testing. Essential issues related to the scalability of these modular sensor ensembles are explored as are attempts to move such multiplexed and multiclass platforms into large-scale clinical trials. Recent efforts in these bead sensors have shown advantages over planar microarrays in terms of their capacity to generate multiplexed test results with shorter analysis times. Through high surface-to-volume ratios and encoding capabilities; porous bead-based ensembles; when combined with microfluidic elements; allow for high-throughput testing for enzymatic assays; general chemistries; protein; antibody and oligonucleotide applications

The genome sequence of Streptomyces lividans 66 reveals a novel tRNA-dependent peptide biosynthetic system within a metal-related genomic island

Microbial Biotechnolog

Cyclodipeptide synthases, a family of class-I aminoacyl-tRNA synthetase-like enzymes involved in non-ribosomal peptide synthesis

Cyclodipeptide synthases (CDPSs) belong to a newly defined family of enzymes that use aminoacyl-tRNAs (aa-tRNAs) as substrates to synthesize the two peptide bonds of various cyclodipeptides, which are the precursors of many natural products with noteworthy biological activities. Here, we describe the crystal structure of AlbC, a CDPS from Streptomyces noursei. The AlbC structure consists of a monomer containing a Rossmann-fold domain. Strikingly, it is highly similar to the catalytic domain of class-I aminoacyl-tRNA synthetases (aaRSs), especially class-Ic TyrRSs and TrpRSs. AlbC contains a deep pocket, highly conserved among CDPSs. Site-directed mutagenesis studies indicate that this pocket accommodates the aminoacyl moiety of the aa-tRNA substrate in a way similar to that used by TyrRSs to recognize their tyrosine substrates. These studies also suggest that the tRNA moiety of the aa-tRNA interacts with AlbC via at least one patch of basic residues, which is conserved among CDPSs but not present in class-Ic aaRSs. AlbC catalyses its two-substrate reaction via a ping-pong mechanism with a covalent intermediate in which l-Phe is shown to be transferred from Phe-tRNAPhe to an active serine. These findings provide insight into the molecular bases of the interactions between CDPSs and their aa-tRNAs substrates, and the catalytic mechanism used by CDPSs to achieve the non-ribosomal synthesis of cyclodipeptides

Actinomycete integrative and conjugative elements

This paper reviews current knowledge on actinomycete integrative and conjugative elements (AICEs). The best characterised AICEs, pSAM2 of Streptomyces ambofaciens (10.9 kb), SLP1 (17.3 kb) of Streptomyces coelicolor and pMEA300 of Amycolatopsis methanolica (13.3 kb), are present as integrative elements in specific tRNA genes, and are capable of conjugative transfer. These AICEs have a highly conserved structural organisation, with functional modules for excision/integration, replication, conjugative transfer, and regulation. Recently, it has been shown that pMEA300 and the related elements pMEA100 of Amycolatopsis mediterranei and pSE211 of Saccharopolyspora erythraea form a novel group of AICEs, the pMEA-elements, based on the unique characteristics of their replication initiator protein RepAM. Evaluation of a large collection of Amycolatopsis isolates has allowed identification of multiple pMEA-like elements. Our data show that, as AICEs, they mainly coevolved with their natural host in an integrated form, rather than being dispersed via horizontal gene transfer. The pMEA-like elements could be separated into two distinct populations from different geographical origins. One group was most closely related to pMEA300 and was found in isolates from Australia and Asia and pMEA100-related sequences were present in European isolates. Genome sequence data have enormously contributed to the recent insight that AICEs are present in many actinomycete genera. The sequence data also provide more insight into their evolutionary relationships, revealing their modular composition and their likely combined descent from bacterial plasmids and bacteriophages. Evidence is accumulating that AICEs act as modulators of host genome diversity and are also involved in the acquisition of secondary metabolite clusters and foreign DNA via horizontal gene transfer. Although still speculative, these AICEs may play a role in the spread of antibiotic resistance factors into pathogenic bacteria. The novel insights on AICE characteristics presented in this review may be used for the effective construction of new vectors that allows us to engineer and optimise strains for the production of commercially and medically interesting secondary metabolites, and bioactive proteins

DNA molecular configurations in flows near adsorbing and nonadsorbing surfaces

We investigate experimentally λ-phage and T2-coliphage DNA molecules near both non-adsorbing glass and adsorbing 3-aminopropyltriethoxysilane (APTES)-coated glass surfaces in a simple steady shearing flow generated by a torsional flow cell. The DNA molecular deformations near the surface are found to be considerably weaker than in bulk flow at the same shear rate. This affects the DNA molecule’s deposition and stretching on the adsorbing surface. Surprisingly, for a simple shearing flow in the torsional shearing device, the observed stretch, for molecules both near (<10 µm) the surface and adsorbed to it, is much less than predicted by simulations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47215/1/397_2004_Article_370.pd