1,721,599 research outputs found
Le second centenaire d'Antonio Rosmini : G. Messina, I presocratici nel pensiero di Rosmini.
No full textLévêque Pierre. Le second centenaire d'Antonio Rosmini : G. Messina, I presocratici nel pensiero di Rosmini.. In: Dialogues d'histoire ancienne, vol. 26, n°1, 2000. pp. 254-255
Comparative myogenesis in teleosts and mammals
No full textSkeletal myogenesis has been and is currently under extensive study in both mammals and teleosts, with the latter providing a good model for skeletal myogenesis because of their flexible and conserved genome. Parallel investigations of muscle studies using both these models have strongly accelerated the advances in the field. However, when transferring the knowledge from one model to the other, it is important to take into account both their similarities and differences. The main difficulties in comparing mammals and teleosts arise from their different temporal development. Conserved aspects can be seen for muscle developmental origin and segmentation, and for the presence of multiple myogenic waves. Among the divergences, many fish have an indeterminate growth capacity throughout their entire life span, which is absent in mammals, thus implying different post-natal growth mechanisms. This review covers the current state of the art on myogenesis, with a focus on the most conserved and divergent aspects between mammals and teleosts
Un accès direct à Empédocle : G. Imbraguglia, G. Badolati, R. Morchio, A. Battegazzore, G. Messina, Index Empedocleus.
No full textLévêque Pierre. Un accès direct à Empédocle : G. Imbraguglia, G. Badolati, R. Morchio, A. Battegazzore, G. Messina, Index Empedocleus.. In: Dialogues d'histoire ancienne, vol. 18, n°2, 1992. pp. 367-368
Study of DNA replication in mammalian terminally differentiated cells upon cell cycle reactivation
Full text linkTerminally differentiated (TD) cells are characterized by the permanent inability to proliferate. In culture, skeletal muscle myotubes (Mt), a model system of TD, can be forced to reenter the cell cycle by several means, including expression of adenovirus E1A, overexpression of cyclin D1 and CDK4/6, or depletion of CDK inhibitors. Nonetheless, cell cycle reactivation in Mt never results in a long-term survival and effective proliferation. Reactivated Mt suffer heavy DNA damage, and die by apoptosis or mitotic catastrophe. Critically, they are not able to fully duplicate their DNA.
The purpose of this thesis is to understand the molecular bases that prevent Mt to lead a regular and complete replication. We investigated through functional (i.e., biochemical) problems and structural obstacles.
Functionally, we found that Mt attempt to duplicate their DNA with extremely low levels of deoxythimidine triphosphate (dTTP). This is explained by failure to upregulate thymidine kinase (TK) upon cell cycle reentry. Exogenous administration of deoxythymidine or expression of TK increased DNA synthesis, though it never attained completion.
We then used Xenopus laevis egg extracts (XEE) to study DNA replication in nuclei from Mt and proliferating (P) or quiescent (Q) myoblasts. XEE are able to complement any functional defect, highlighting structural obstacles. Maximal DNA replication in Mt nuclei was strikingly lower than in those from Q and P myoblasts, revealing the presence of a barrier that prevent Mt to replicate the whole genome. To investigate at which level of nuclear complexity this obstacle lies, we studied replication kinetics in naked and nucleosome-assembled DNA from Mt, in comparison with similar samples from P myoblasts. Together, all results showed that both functional and structural obstacles prevent full DNA duplication in myotubes. Furthermore, they suggest that hitherto unexplored peculiarities of their chromatin are ultimately responsible for the inability of these cells to proliferate
Decoding the role of the lncRNA HOTAIRM1 in human motor neurons
Full text linkThe mammalian genome produces thousands of long non-coding RNAs (lncRNAs), which have been demonstrated to be fundamental in the control of many biological processes. These molecules play a crucial role in the multilayered regulation of physiological and disease-related gene expression programs, having significant implications in shaping central nervous system (CNS) complexity.
Neuronal differentiation is a timely and spatially regulated process, relying on precisely orchestrated gene expression control. The coordinated activity of transcription factors and non-coding RNAs (ncRNAs), organized in intricate regulatory networks, drives cell fate specification ensuring correct and specific neuronal functions. We previously described,1 at both the molecular and functional level, the lncRNA nHOTAIRM1 as a neuronal-enriched transcript, which is upregulated during in vitro neuronal differentiation and highly expressed in post-mitotic motor neurons (MNs). We demonstrated that the nuclear nHOTAIRM1, even if much less abundant than its cytoplasmic counterpart, it is involved in the achievement of correct neuronal differentiation timing as an epigenetic regulator of NEUROG2 expression.1 Remarkably, among all human brain tissues, nHOTAIRM1 is specifically expressed in the spinal cord. Consistently, we found that nHOTAIRM1 accumulates in MN-enriched ventral spinal cord lineages differentiated from human induced pluripotent stem cells (iPSCs).1 All this evidence prompted us to further investigate the role of the highly expressed nHOTAIRM1 specifically on MN generation and/or function, to ultimately determine whether its deregulation affects MN differentiation and activity. To experimentally address these questions, here we applied a genome editing-based loss-of-function approach to a model system that efficiently recapitulates spinal MN differentiation, and we identified key nHOTAIRM1 target genes implicated in MN maturation, morphology and activity. Our findings allowed us to conclude that nHOTAIRM1 directs multiple crucial aspects of MN physiology, from their development to the acquisition of appropriate morphological features and motor function
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
G. Messina, S. J. — Der Ureprung dur Magier und die zarathustrisehe Religion. (Scripta Pontificii Instituti Biblici). Roma, Pontificio Instituto Bibiico, 1930
No full textMouterde René. G. Messina, S. J. — Der Ureprung dur Magier und die zarathustrisehe Religion. (Scripta Pontificii Instituti Biblici). Roma, Pontificio Instituto Bibiico, 1930. In: Mélanges de l'Université Saint-Joseph, tome 15, 1930. pp. 327-328
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