In the search for the low-complexity sequences in prokaryotic and eukaryotic genomes: how to derive a coherent picture from global and local entropy measures

We investigate on a possible way to connect the presence of Low-Complexity Sequences (LCS) in DNA genomes and the nonstationary properties of base correlations. Under the hypothesis that these variations signal a change in the DNA function, we use a new technique, called Non-Stationarity Entropic Index (NSEI) method, and we prove that this technique is an efficient way to detect functional changes with respect to a random baseline. The remarkable aspect is that NSEI does not imply any training data or fitting parameter, the only arbitrarity being the choice of a marker in the sequence. We make this choice on the basis of biological information about LCS distributions in genomes. We show that there exists a correlation between changing the amount in LCS and the ratio of long- to short-range correlation

IDENTIFICATION OF C-KIT/CD105 AND ISL-1 CELLS IN HUMAN FETAL AND INFANT HEARTS

During embryogenesis, the mammalian heart develops from a primitive heart tube, which derives from two bilateral primary heart fields located in the lateral plate mesoderm. Later on in the development process, the atrioventricular (A-V) canal and the sinu-atrial segment, at the venous pole, and the conotruncus, at the arterial pole, are added to the heart tube just prior to tube looping. In 2001 Waldo and colleagues and Kelly and colleagues demonstrated the presence of a secondary or anterior heart field in the ventral pharyngeal mesoderm. This region contains a pool of NKX2.5 and GATA-4 positive precardiac cells which migrate to the arterial pole of the primary heart tube. Isl-1 is a marker of the secondary heart field, and Isl-1+ fate-mapped cells can contribute to the right ventricle and outflow tract of the developing mouse heart. Most studies concerning the localization of cardiac precursor cells in the developing heart have been performed in mice or chicks, whereby the localization and identification of cardiac precursor cells in the human fetal and adult heart has been investigated only by Limana and colleagues, with their analysis limited to epicardium, and CD34+ or c-Kit+ cells. Isolation and characterization of adult human cardiac stem cells was characterized by the expression of c-Kit, the receptor for stem cell factor, and CD105, the regulatory component of the transforming growth factor-ß receptor complex important in angiogenesis and hematopoiesis. In view of this, in the present study, we analysed, by immunohistochemistry, the presence of c-Kit+/CD105+ and Isl-1+ cells in human normal hearts from infants and from fetuses at different gestational ages. We found that cells double positive for c-kit and CD105, and single positive for Isl-1 were present solely after the 18th week of gestation. Isl-1+ cells were localized also inside vessels, like non resident cells, in infant hearts

EFFECTS OF CONJUGATED LINOLEIC ACID AND RESISTANCE TRAINING IN RECREATIONAL ATHLETES

Conjugated linoleic acid (CLA) is a mixture of positional and geometrical isomers of linoleic acid, that are known to posses several physiological effects such as enhancing immune response, reducing arteriosclerosis risk, and inhibiting carcinogenesis. Over the last decade, the use of CLA supplement has become widespread among elite and recreational athletes because it should increase training effects, improve fat oxidation, increase energy delivery, reduce body weight, improve lipid profile, and so on. The purpose of this project is to investigate whether CLA supplementation after a resistance training session affects general markers of muscle damage, total testosterone, cortisol and sex hormone binding globulin. In a double-blind and randomized manner 13 recreational athletes were randomly assigned to supplement their diet with 6 g per day of an sunflower oil placebo or 6 g per day of CLA for 21 days. After two weeks of wash-out, all subjects crossed over to the opposite group for an additional 21 days. The 3 weeks of supplementation were preceded and followed by a resistance training session involved 8 exercise, chosen to include all major muscle groups, consisting of 3 sets of 10 repetitions at approximately 75-80% of one-repetition maximum. Before and after the training session were drawn blood to measure the creatine phosphokinase, lactate dehydrogenase, creatine kinase mass, total testosterone, cortisol and sex hormone binding globulin concentrations. Measurements at baseline and after the 3 week of supplementation included body composition and stregth. The results indicate that CLA supplementation during resistance training should increase the anabolic effect and decrease the catabolic effects of training on muscle protein

Endurance exercise and conjugated linoleic acid (CLA) supplementation up-regulate CYP17A1 and stimulate testosterone biosynthesis.

A new role for fat supplements, in particular conjugated linoleic acid (CLA), has been delineated in steroidogenesis, although the underlying molecular mechanisms have not yet been elucidated. The aims of the present study were to identify the pathway stimulated by CLA supplementation using a cell culture model and to determine whether this same pathway is also stimulated in vivo by CLA supplementation associated with exercise. In vitro, Leydig tumour rat cells (R2C) supplemented with different concentrations of CLA exhibited increasing testosterone biosynthesis accompanied by increasing levels of CYP17A1 mRNA and protein. In vivo, trained mice showed an increase in free plasma testosterone and an up-regulation of CYP17A1 mRNA and protein. The effect of training on CYP17A1 expression and testosterone biosynthesis was significantly higher in the trained mice supplemented with CLA compared to the placebo. The results of the present study demonstrated that CLA stimulates testosterone biosynthesis via CYP17A1, and endurance training led to the synthesis of testosterone in vivo by inducing the overexpression of CYP17A1 mRNA and protein in the Leydig cells of the testis. This effect was enhanced by CLA supplementation. Therefore, CLA-associated physical activity may be used for its steroidogenic property in different fields, such as alimentary industry, human reproductive medicine, sport science, and anti-muscle wasting

HSP90 AND ENOS PARTIALLY CO-LOCALIZE AND CHANGE CELLULAR LOCALIZATION IN RELATION TO DIFFERENT ECM COMPONENTS IN 2D AND 3D CULTURES OF ADULT RAT CARDIOMYCYTES

BACKGROUND INFORMATION: Cultivation techniques promoting three-dimensional organization of mammalian cells are of increasing interest, since they confer key functionalities of the native ECM (extracellular matrix) with a power for regenerative medicine applications. Since ECM compliance influences a number of cell functions, Matrigel-based gels have become attractive tools, because of the ease with which their mechanical properties can be controlled. In the present study, we took advantage of the chemical and mechanical tunability of commonly used cell culture substrates, and co-cultures to evaluate, on both two- and three-dimensional cultivated adult rat cardiomyocytes, the impact of ECM chemistry and mechanics on the cellular localization of two interacting signalling proteins: HSP90 (heat-shock protein of 90 kDa) and eNOS (endothelial nitric oxide synthase). RESULTS: Freshly isolated rat cardiomyocytes were cultured on fibronectin, Matrigel gel or laminin, or in co-culture with cardiac fibroblasts, and tested for both integrity and viability. As validation criteria, integrity of both plasma membrane and mitochondria was evaluated by transmission electron microscopy. Cell sensitivity to microenvironmental stimuli was monitored by immunofluorescence and confocal microscopy. We found that HSP90 and eNOS expression and localization are affected by changes in ECM composition. Elaboration of the images revealed, on Matrigel-cultured cardiomyocytes, areas of high co-localization between HSP90 and eNOS and co-localization coefficients, which indicated the highest correlation with respect to the other substrates. CONCLUSIONS: Our three-dimensional adult cardiomyocyte cultures are suitable for both analysing cell-ECM interactions at electron and confocal microscopy levels and monitoring micro-environment impact on cardiomyocyte phenotyp