Stimulation of rat cutaneous fibroblasts and their synthetic activity by implants of powdered nacre (mother of pearl)

The components of the cutaneous envelope, the epidermis and the dermis, change in response to aging or environmental stress factors. The fibroblasts involved in maintaining skin tone are the main targets. Nacre, mother of pearl, from Pinctada maxima, which can stimulate and regulate bone forming cells, was implanted in the dermis of rats to test its action on the skin fibroblasts. This report describes the effect of nacre on the skin fibroblast recruitment and physiological activity. It resulted in enhanced extracellular matrix synthesis and the production of components implicated in cell to cell adhesion and communication (such as decorine) and in tissue regeneration (type I and type III collagens). The nacre implant produced a well vascularized tissue. The physiological conditions in the region around the implant are thus those required for the positive interactions between the dermis and epidermis which are fundamental for the physiological function of the skin.     

Short term optical defocus perturbs normal developmental shifts in retina/RPE protein abundance

Background

Myopia (short-sightedness) affects approximately 1.4 billion people worldwide, and prevalence is increasing. Animal models induced by defocusing lenses show striking similarity with human myopia in terms of morphology and the implicated genetic pathways. Less is known about proteome changes in animals. Thus, the present study aimed to improve understanding of protein pathway responses to lens defocus, with an emphasis on relating expression changes to no lens control development and identifying bidirectional and/or distinct pathways across myopia and hyperopia (long-sightedness) models.

Results

Quantitative label-free proteomics and gene set enrichment analysis (GSEA) were used to examine protein pathway expression in the retina/RPE of chicks following 6 h and 48 h of myopia induction with ??10 dioptre (D) lenses, hyperopia induction with +10D lenses, or normal no lens rearing. Seventy-one pathways linked to cell development and neuronal maturation were differentially enriched between 6 and 48 h in no lens chicks. The majority of these normal developmental changes were disrupted by lens-wear (47 of 71 pathways), however, only 11 pathways displayed distinct expression profiles across the lens conditions. Most notably, negative lens-wear induced up-regulation of proteins involved in ATP-driven ion transport, calcium homeostasis, and GABA signalling between 6 and 48 h, while the same proteins were down-regulated over time in normally developing chicks. Glutamate and bicarbonate/chloride transporters were also down-regulated over time in normally developing chicks, and positive lens-wear inhibited this down-regulation.

Conclusions

The chick retina/RPE proteome undergoes extensive pathway expression shifts during normal development. Most of these pathways are further disrupted by lens-wear. The identified expression patterns suggest close interactions between neurotransmission (as exemplified by increased GABA receptor and synaptic protein expression), cellular ion homeostasis, and associated energy resources during myopia induction. We have also provided novel evidence for changes to SLC-mediated transmembrane transport during hyperopia induction, with potential implications for signalling at the photoreceptor-bipolar synapse. These findings reflect a key role for perturbed neurotransmission and ionic homeostasis in optically-induced refractive errors, and are predicted by our Retinal Ion Driven Efflux (RIDE) model.

     

Evidence for thiosulfate sulfur transferase (rhodanese) trithionate reductase and tetrathionate reductase activities in Neisseria gonorrhoeae

Abstract Neisseria gonorrhoeae is unable to grow with sulfate but can use thiosulfate as sole source of sulfur.
Thiosulfate sulfur transferase (TST) (rhodanese) activity was present in the cytoplasmic soluble fraction. In the same extract, thiosulfate reductase (TSR), trithionate reductase and tetrathionate reductase activities were also detected using hydrogen as electron donor in the presence of viologen dyes and hydrogenase from Desulfovibrio gigas .
The significance of and the possible relationship between these different activities are discussed.     

A novel binding protein for a member of CyP40-type Cyclophilins: N.crassa CyPBP37, a growth and thiamine regulated protein homolog to yeast Thi4p

Cyclophilins belong to the family of peptidyl-prolyl cis/trans isomerases (PPIases), which are ubiquitous and highly conserved enzymes capable of cis/trans isomerizing Xaa-Pro peptide bonds. Members of the CyP40-type cyclophilins have originally been described as components of hormone receptor complexes. Here, we describe NcCyP41, a CyP40 ortholog from Neurospora crassa, its expression in Escherichia coli and subsequent purification. Characterization of NcCyP41 reveals that it is a heat shock protein, which is active as a cyclosporin A-sensitive PPIase. Affinity chromatography using immobilized recombinant NcCyP41 yielded two major NcCyP41-binding proteins: Hsp80 (a Hsp90 ortholog from N.crassa) and CyPBP37. CyPBP37 has not been described. In addition, this is the first record describing an interaction between a member of Cyp40-type cyclophilins and of CyPBP37-type proteins, respectively. CyPBP37 expression is repressed by thiamine and in the stationary phase in N.crassa. CyPBP37 is present in different isoforms. The expression of a CyPBP37 ortholog in yeast, Thi4p, is diminished in a mutant lacking one of the two CyP40 orthologs (Cpr7p). In addition, the DeltaCpr7p deletion mutant shows a thiamine-dependent growth defect. We conclude that, in yeast, Cpr7p and Thi4p interact functionally.     

Comparison of sludge and clinical isolates of Listeria monocytogenes

AIMS: Listeria monocytogenes strains isolated in the same geographical area from sewage sludge and from patients presenting with listeriosis were compared. METHODS AND RESULTS: All isolates were typed by serotyping, phage typing and SmaI/ApaI pulsed-field gel electrophoresis (PFGE). Among the sludge isolates (n=32), 22 subtypes could be distinguished by the combination of all typing methods. The human isolates (n=11) were distributed into 10 subtypes which clearly differed from those observed among sludge isolates, except for one cluster formed by two related human isolates which showed high similarity in PFGE patterns (SmaI: 92%; ApaI: 89.5%) with one sludge isolate. CONCLUSION: These results suggest the existence of an epidemiological link between sludge and human isolates, but they may also be reflecting the distribution of L. monocytogenes types within the environment. SIGNIFICANCE AND IMPACT OF THE STUDY: Sludge and human L. monocytogenes may be related but further epidemiological studies are necessary to elucidate this point.     

Human 2'-phosphodiesterase localizes to the mitochondrial matrix with a putative function in mitochondrial RNA turnover

The vertebrate 2-5A system is part of the innate immune system and central to cellular antiviral defense. Upon activation by viral double-stranded RNA, 5'-triphosphorylated, 2'-5'-linked oligoadenylate polyribonucleotides (2-5As) are synthesized by one of several 2'-5'-oligoadenylate synthetases. These unusual oligonucleotides activate RNase L, an unspecific endoribonuclease that mediates viral and cellular RNA breakdown. Subsequently, the 2-5As are removed by a 2'-phosphodiesterase (2'-PDE), an enzyme that apart from breaking 2'-5' bonds also degrades regular, 3'-5'-linked oligoadenylates. Interestingly, 2'-PDE shares both functionally and structurally characteristics with the CCR4-type exonuclease-endonuclease-phosphatase family of deadenylases. Here we show that 2'-PDE locates to the mitochondrial matrix of human cells, and comprise an active 3'-5' exoribonuclease exhibiting a preference for oligo-adenosine RNA like canonical cytoplasmic deadenylases. Furthermore, we document a marked negative association between 2'-PDE and mitochondrial mRNA levels following siRNA-directed knockdown and plasmid-mediated overexpression, respectively. The results indicate that 2'-PDE, apart from playing a role in the cellular immune system, may also function in mitochondrial RNA turnover.     

Thiosulfate, polythionates and elemental sulfur assimilation and reduction in the bacterial world

Among sulfur compounds, thiosulfate and polythionates are present at least transiently in many environments. These compounds have a similar chemical structure and their metabolism appears closely related. They are commonly used as energy sources for photoautotrophic or chemolithotrophic microorganisms, but their assimilation has been seldom studied and their importance in bacterial physiology is not well understood. Almost all bacterial strains are able to cleave these compounds since they possess thiosulfate sulfur transferase, thiosulfate reductase or S-sulfocysteine synthase activities. However, the role of these enzymes in the assimilation of thiosulfate or polythionates has not always been clearly established. Elemental sulfur is, on the contrary, very common in the environment. It is an energy source for sulfur-reducing eubacteria and archaebacteria and many sulfur-oxidizing archaebacteria. A phenomenon still not well understood is the 'excessive assimilatory sulfur metabolism' as observed in methanogens which perform a sulfur reduction which exceeds their anabolic needs without any apparent benefit. In heterotrophs, assimilation of elemental sulfur is seldom described and it is uncertain whether this process actually has a physiological significance. Thus, reduction of thiosulfate and elemental sulfur is a common but incompletely understood feature among bacteria. These activities could give bacteria a selective advantage, but further investigations are needed to clarify this possibility. Presence of thiosulfate, polythionates and sulfur reductase activities does not imply obligatorily that these activities play a role in thiosulfate, polythionates or sulfur assimilation as these compounds could be merely intermediates in bacterial metabolism. The possibility also exists that the assimilation of these sulfur compounds is just a side effect of an enzymatic activity with a completely different function. As long as these questions remain unanswered, our understanding of sulfur and thiosulfate metabolism will remain incomplete.     

Characterization of the major iron-regulated protein of Neisseria gonorrhoeae and Neissereria meningitidis

The major iron-regulated protein (MIRP) was purified, from both Neisseria gonorrhoeae and N. meningitidis by selective extraction with cetyltrimethylammonium bromide followed by ion-exchange and moleculair-seive chromatography. Solutions of the purified proteins had a characteristic pink color. The overall amino acid composition of these proteins was similar, although differences were noted in the number of serine, threonine, and lysine residues. Nevertheless, the N-terminal amino acid sequence was identical through 47 residues for both the meningococcal and gonococcal MIRP. Plasma emission spectrophotometry revealed that the meningococcal 37K protein contained ca. 1 mole Fe/mole protein.     

Tom34: a cytosolic cochaperone of the Hsp90/Hsp70 protein complex involved in mitochondrial protein import

Most mitochondrial membrane proteins are synthesized in the cytosol and must be delivered to the organelle in an unfolded, import competent form. In mammalian cells, the cytosolic chaperones Hsp90 and Hsp70 are part of a large cytosolic complex that deliver the membrane protein to the mitochondrion by docking with the import receptor Tom70. These two abundant chaperones have other functions in the cell suggesting that the specificity for the targeting of mitochondrial proteins requires the addition of specific factors within the targeting complex. We identify Tom34 as a cochaperone of Hsp70/Hsp90 in mitochondrial protein import. We show that Tom34 is an integral component with Hsp70 and Hsp90 in the large complex. We also demonstrate the role of Tom34 in the mitochondrial import process, as the addition of an excess of Tom34 prevents efficient mitochondrial translocation of precursor proteins that have requirements for Hsp70/Hsp90. Tom34 exhibits an affinity for mitochondrial preproteins of the Tom70 translocation pathway as demonstrated by binding assays using in vitro translated proteins as baits. In addition, we examined the specificity and the size of different complex cytosolic machines. Separation of different radiolabeled cell-free translated proteins on Native-PAGE showed the presence of a high molecular weight complex which binds hydrophobic proteins. Importantly we show that the formation of the chaperone cytosolic complex that mediates the targeting of proteins to the mitochondria contains Tom34 and assembles in the presence of a fully translated substrate protein.