Birch leaves and branches as a source of ice-nucleating macromolecules

Birch pollen are known to release ice-nucleating macromolecules (INM), but little is known about the production and release of INM from other parts of the tree. We examined the ice nucleation activity of samples from 10 different birch trees (Betula spp.). Samples were taken from nine birch trees in Tyrol, Austria, and from one tree in a small urban park in Vienna, Austria. Filtered aqueous extracts of 30 samples of leaves, primary wood (new branch wood, green in colour, photosynthetically active), and secondary wood (older branch wood, brown in colour, with no photosynthetic activity) were analysed in terms of ice nucleation activity using VODCA (Vienna Optical Droplet Crystallization Analyser), a cryo microscope for emulsion samples. All samples contained ice-nucleating particles in the submicron size range. Concentrations of ice nuclei ranged from 6.7×104 to 6.1×109&thinsp;mg−1 sample. Mean freezing temperatures varied between −15.6 and −31.3&thinsp;°C; the range of temperatures where washes of birch pollen and dilutions thereof typically freeze. The freezing behaviour of three concentrations of birch pollen washing water (initial wash, 1&thinsp;:&thinsp;100, and 1&thinsp;:&thinsp;10&thinsp;000) were significantly associated with more than a quarter of our samples, including some of the samples with highest and lowest activity. This indicates a relationship between the INM of wood, leaves, and pollen. Extracts derived from secondary wood showed the highest concentrations of INM and the highest freezing temperatures. Extracts from the leaves exhibited the highest variation in INM and freezing temperatures. Infrared spectra of the extracts and tested birch samples show qualitative similarity, suggesting the chemical components may be broadly similar.</p

Erythropoietin increases myelination in oligodendrocytes: gene expression profiling reveals early induction of genes involved in lipid transport and metabolism

Several studies have shown that erythropoietin (EPO) has neuroprotective or neuroreparative actions on diseases of the nervous system, and that improves oligodendrocyte differentiation and myelination in vivo and in vitro. This study aims at investigating the early molecular mechanisms for the pro-myelinating action of EPO at the gene expression level. For this purpose, we used a differentiating oligodendrocyte precursor cell line, rat CG4 cells. Cells were differentiated or not, and then treated with EPO for 1 or 20 h. RNA was extracted and changes in the gene expression profile were assessed using microarray analysis. Experiments were performed in biological replicates of n=4. Differentiation alone changed the expression of 11% of transcripts (2,663 out of 24,272), representing 2,436 genes, half of which were up-regulated and half down-regulated. At 20 h of treatment, EPO significantly affected the expression of 99 genes that were already regulated by differentiation and of 150 genes that were not influenced by differentiation alone. Analysis of the transcripts most up-regulated by EPO identified several genes involved in lipid transport (e.g. Cd36) and lipid metabolism (Ppargc1a/Pgc1alpha, Lpin1, Pnlip, Lpin2, Ppard, Plin2) along with Igf1 and Igf2, growth factors known for their pro-myelinating action. All these genes where only induced by EPO and not by differentiation alone, except for Pnlip which was highly induced by differentiation and augmented by EPO. Results were validated by quantitative PCR. These findings suggest that EPO might increase remyelination by inducing insulin-like growth factors and increasing lipid metabolism

Gene expression throughout a vertebrate's embryogenesis

Abstract Background Describing the patterns of gene expression during embryonic development has broadened our understanding of the processes and patterns that define morphogenesis. Yet gene expression patterns have not been described throughout vertebrate embryogenesis. This study presents statistical analyses of gene expression during all 40 developmental stages in the teleost Fundulus heteroclitus using four biological replicates per stage. Results Patterns of gene expression for 7,000 genes appear to be important as they recapitulate developmental timing. Among the 45% of genes with significant expression differences between pairs of temporally adjacent stages, significant differences in gene expression vary from as few as five to more than 660. Five adjacent stages have disproportionately more significant changes in gene expression (&gt; 200 genes) relative to other stages: four to eight and eight to sixteen cell stages, onset of circulation, pre and post-hatch, and during complete yolk absorption. The fewest differences among adjacent stages occur during gastrulation. Yet, at stage 16, (pre-mid-gastrulation) the largest number of genes has peak expression. This stage has an over representation of genes in oxidative respiration and protein expression (ribosomes, translational genes and proteases). Unexpectedly, among all ribosomal genes, both strong positive and negative correlations occur. Similar correlated patterns of expression occur among all significant genes. Conclusions These data provide statistical support for the temporal dynamics of developmental gene expression during all stages of vertebrate development

Contribution of Social Isolation, Restraint, and Hindlimb Unloading to Changes in Hemodynamic Parameters and Motion Activity in Rats

The most accepted animal model for simulation of the physiological and morphological consequences of microgravity on the cardiovascular system is one of head-down hindlimb unloading. Experimental conditions surrounding this model include not only head-down tilting of rats, but also social and restraint stresses that have their own influences on cardiovascular system function. Here, we studied levels of spontaneous locomotor activity, blood pressure, and heart rate during 14 days under the following experimental conditions: cage control, social isolation in standard rat housing, social isolation in special cages for hindlimb unloading, horizontal attachment (restraint), and head-down hindlimb unloading. General activity and hemodynamic parameters were continuously monitored in conscious rats by telemetry. Heart rate and blood pressure were both evaluated during treadmill running to reveal cardiovascular deconditioning development as a result of unloading. The main findings of our work are that: social isolation and restraint induced persistent physical inactivity, while unloading in rats resulted in initial inactivity followed by normalization and increased locomotion after one week. Moreover, 14 days of hindlimb unloading showed significant elevation of blood pressure and slight elevation of heart rate. Hemodynamic changes in isolated and restrained rats largely reproduced the trends observed during unloading. Finally, we detected no augmentation of tachycardia during moderate exercise in rats after 14 days of unloading. Thus, we concluded that both social isolation and restraint, as an integral part of the model conditions, contribute essentially to cardiovascular reactions during head-down hindlimb unloading, compared to the little changes in the hydrostatic gradient

Chapitre 14. LES CONTRE-MESURES: Prévenir les altérations physiologiques induites par l’environnement spatial

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Myopathie métabolique généralisée dans l'insuffisance cardiaque (facteurs impliqués et conséquences fonctionnelles)

Les patients souffrant d'insuffisance cardiaque (IC) se plaignent d'une incapacité à l'exercice physique. Les travaux précédents dans notre laboratoire ont montré une myopathie métabolique généralisée dans l'IC. Le caractère généralisé de la myopathie dans l'IC suggère l'implication de facteurs systémiques. Dans ce travail, nous avons étudié l'implication éventuelle de deux agents [nitrique oxyde (NO) produit par la nitrique oxyde synthase endothéliale (NOSe) et l'angiotensine II (AngII)] considérablement altérés dans l'IC et dans le développement de la myopathie métabolique généralisée. Les résultats obtenus suggèrent que l'action bénéfique des inhibiteurs de l'enzyme de conversion sur le profil métabolique musculaire nécessite une diminution de la " post-charge " cardiaque. Nous avons également montré le rôle important du NO produit par la NOSe dans le métabolisme énergétique du muscle squelettique oxydatif ainsi que dans le maintien de la capacité physique de l'organismePatients suffering from heart failure (HF) complain of intolerance to exercise. Previous work in our laboratory has shown that HF (by aortic stenosis) in rats is associated with a myopathy that alters energy metabolism in different muscles. The generalized character of the metabolic myopathy in HF suggests that some systemic factors could be involved. Angiotensin II (AngII) and nitric oxide produced by endothelial nitric oxide synthase (eNOS) are two systemic factors whose production is greatly changed in heart failure. Angiotensin converting enzyme inhibitors (IEC) are known to improve the mortality and morbidity rates in HF. Our results have shown that the beneficial effect of IEC on the metabolic myopathy is probably associated with a reduction in afterload. We have shown that eNOS deficiency induces a significant reduction of mitochondrial oxidative capacity specifically in slow-twitch muscle and we have demonstrated that eNOS is necessary for maintaining normal physical activity.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF