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Salvador Martinez - One of the best experts on this subject based on the ideXlab platform.
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Wnt1 signal determines the patterning of the dienCephalic dorso-ventral axis.
Brain Structure & Function, 2015Co-Authors: Maria Navarro-garberi, Carlos Bueno, Salvador MartinezAbstract:The diencephalon is a complex brain area that derives from the caudal region of the prosencephalon. This structure is divided into four longitudinal neuroepithelial zones: roof, alar, basal and floor plates, which constitute its dorso-ventral (DV) columnar domains. Morphogenetic differences between alar and basal plates in the prosencephalon and mesencephalon contribute to the characteristic expansion of alar plate derivatives in the brain and the formation of the Cephalic Flexure. Although differential histogenesis among DV regions seems to be relevant in understanding structural and functional complexity of the brain, most of our knowledge about DV regionalization comes from the spinal cord development. Therefore, it seems of interest to study the molecular mechanisms that govern DV patterning in the diencephalon, the brain region where strong differences in size and complexity between alar and basal derivatives are evident in all vertebrates. Different morphogenetic signals, which induce specific progenitors fate to the neighboring epithelium, are involved in the spinal cord DV patterning. To study if Wnt1, one of these signaling molecules, has a role for the establishment of the dienCephalic longitudinal domains, we carried out gain- and loss-of-function experiments, using mice and chick embryos. Our results demonstrated functional differences in the molecular mechanisms downstream of Wnt1 function in the diencephalon, in relation to the spinal cord. We further demonstrated that Bmp4 signal induces Wnt1 expression in the diencephalon, unraveling a new molecular regulatory code downstream of primary dorsalizing signals to control ventral regionalization in the diencephalon.
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Molecular characterization, structure and developmental expression of Megane bHLH factor.
Gene, 2006Co-Authors: Jordi Guimera, Salvador Martinez, Daniela M. Vogt Weisenhorn, Diego Echevarria, Wolfgang WurstAbstract:We report here the full-length sequence identification, molecular characterization, detailed demarcation expression analysis relevant to morphological marker genes and mapping of a bHLH transcription gene, referred to as Megane (Mgn). Mgn protein is structurally related to the neurogenic Drosophila hairy and Enhancer of split (h/E(spl)) proteins. The unique structural properties of Mgn factor in several characteristic residues define the gene as related to h/E(spl), but distinguish it from previously identified mammalian members of the family. Mgn is a single copy gene on mouse chromosome 8 and encodes a 27kDa protein that functions in the nucleus. First expression of Mgn is detected at mouse embryonic day 9.5 within the most rostral part of the Cephalic Flexure of the developing midbrain. Later, Mgn expression extends into other alar areas of the midbrain and forebrain, developmentally controlled in a regional specific pattern.
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Neurogenetic Compartments of the Mouse Diencephalon and some Characteristic Gene Expression Patterns
Results and Problems in Cell Differentiation, 2000Co-Authors: Salvador Martinez, Luis PuellesAbstract:In the last 10 years our concept of the developing diencephalon has changed dramatically. This is a consequence of an increasing number of morphological, chemoarchitectural, gene expression and experimental data that resist a satisfactory interpretation within the usual morphological schema suggested by textbooks, represented by the so-called columnar view of the vertebrate forebrain. The columnar paradigm was instaurated by Herrick (1910), who divided the vertebrate diencephalon into four superposed columns separated by ventricular sulci. This schema was later supported by numerous adherents, among which Kuhlenbeck played a singular role (Kuhlenbeck 1973, and earlier work reviewed therein). The four columns were called epithalamus, thalamus dorsalis, thalamus ventralis and hypothalamus (from dorsal to ventral). They were held to be longitudinal parts of the neural tube, though this view is only possible by arbitrary disregard of the notorius axial bending of the rostral neural tube at the Cephalic Flexure (Keyser 1972; Puelles and Rubenstein 1993; Puelles 1995). Among other problems (see Puelles 1995), this schema typically dealt poorly with the pretectum, causing many authors to fail to distinguish it adequately from the dorsal thalamus, the epithalamus or the midbrain roof. Various descriptive embryologists noticed over the years the difficulties of the columnar approach, favoring a segmental paradigm, but did not achieve a substantial impact with their alternative interpretations (Rendahl 1924; Tello 1934; Bergquist 1954; Coggeshall 1964; Keyser 1972; Gribnau and Geijsberts 1985). These, nevertheless, finally constituted the base of the present conceptions, together with parallel work on non-mammalian vertebrates.
Zamzuri Idris - One of the best experts on this subject based on the ideXlab platform.
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Searching for the Origin through Central Nervous System: A Review and Thought which Related to Microgravity, Evolution, Big Bang Theory and Universes, Soul and Brainwaves, Greater Limbic System and Seat of the Soul.
The Malaysian journal of medical sciences : MJMS, 2014Co-Authors: Zamzuri IdrisAbstract:Cerebrospinal fluid (CSF) serves buoyancy. The buoyancy thought to play crucial role in many aspects of the central nervous system (CNS). Weightlessness is produced mainly by the CSF. This manuscript is purposely made to discuss its significance which thought contributing towards an ideal environment for the CNS to develop and function normally. The idea of microgravity environment for the CNS is supported not only by the weightlessness concept of the brain, but also the noted anatomical position of the CNS. The CNS is positioned in bowing position (at main Cephalic Flexure) which is nearly similar to an astronaut in a microgravity chamber, fetus in the amniotic fluid at early gestation, and animals and plants in the ocean or on the land. Therefore, this microgravity position can bring us closer to the concept of origin. The hypothesis on ‘the origin’ based on the microgravity were explored and their similarities were identified including the brainwaves and soul. Subsequently a review on soul was made. Interestingly, an idea from Leonardo da Vinci seems in agreement with the notion of seat of the soul at the greater limbic system which has a distinctive feature of “from God back to God”.
Luis Puelles - One of the best experts on this subject based on the ideXlab platform.
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Chapter 10 – Midbrain
The Mouse Nervous System, 2012Co-Authors: Eduardo Puelles, Margaret Martínez-de-la-torre, Charles Watson, Luis PuellesAbstract:Publisher Summary The midbrain or mesencephalon is detected as a distinct neural tubular vesicle from early stages of development. Its name results from its location which is intercalated between the other two primary vesicles. As embryonic development proceeds, the mesenCephalic portion of the neural tube bends progressively ventrally, forming the Cephalic Flexure, and causing the parallel expansion of the dorsal midbrain. The specification of the midbrain is under the influence of the isthmic organizer (IsO), a transverse secondary organizer locus identified at the mid-hindbrain boundary. This organizer emits signals that can both specify and pattern the neighboring tissue found rostrally and caudally to it. The anterior part of the midbrain suffers apoptosis, and the posterior part undergoes a change in fate, resulting specified as anterior midbrain. The neuroepithelial midbrain progenitors are also influenced by other pattern organizers acting upon the dorso-ventral dimension. The midbrain also holds the population of the mesenCephalic trigeminal nucleus, which may be considered to be a peculiar derivative of the midbrain neural crest. There are two clear landmarks that identify the rostral and caudal limits of the midbrain. The location of the isthmic outer constriction of the brainstem identifies the caudal midbrain limit with the isthmus, which is the rostral-most part of the hindbrain. The midbrain develops a number of distinct domains along its dorso-ventral axis.
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Neurogenetic Compartments of the Mouse Diencephalon and some Characteristic Gene Expression Patterns
Results and Problems in Cell Differentiation, 2000Co-Authors: Salvador Martinez, Luis PuellesAbstract:In the last 10 years our concept of the developing diencephalon has changed dramatically. This is a consequence of an increasing number of morphological, chemoarchitectural, gene expression and experimental data that resist a satisfactory interpretation within the usual morphological schema suggested by textbooks, represented by the so-called columnar view of the vertebrate forebrain. The columnar paradigm was instaurated by Herrick (1910), who divided the vertebrate diencephalon into four superposed columns separated by ventricular sulci. This schema was later supported by numerous adherents, among which Kuhlenbeck played a singular role (Kuhlenbeck 1973, and earlier work reviewed therein). The four columns were called epithalamus, thalamus dorsalis, thalamus ventralis and hypothalamus (from dorsal to ventral). They were held to be longitudinal parts of the neural tube, though this view is only possible by arbitrary disregard of the notorius axial bending of the rostral neural tube at the Cephalic Flexure (Keyser 1972; Puelles and Rubenstein 1993; Puelles 1995). Among other problems (see Puelles 1995), this schema typically dealt poorly with the pretectum, causing many authors to fail to distinguish it adequately from the dorsal thalamus, the epithalamus or the midbrain roof. Various descriptive embryologists noticed over the years the difficulties of the columnar approach, favoring a segmental paradigm, but did not achieve a substantial impact with their alternative interpretations (Rendahl 1924; Tello 1934; Bergquist 1954; Coggeshall 1964; Keyser 1972; Gribnau and Geijsberts 1985). These, nevertheless, finally constituted the base of the present conceptions, together with parallel work on non-mammalian vertebrates.
Michael W. Vogel - One of the best experts on this subject based on the ideXlab platform.
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Desire, Disease, and the Origins of the Dopaminergic System
Schizophrenia Bulletin, 2007Co-Authors: Roy V. Sillitoe, Michael W. VogelAbstract:The dopaminergic neurons in the midbrain region of the central nervous system project an extensive network of connections throughout the forebrain, including the neocortex. The midbrain-forebrain dopaminergic circuits are thought to regulate a diverse set of behaviors, from the control of movement to modulation of cognition and desire—because they relate to mood, attention, reward, and addiction. Defects in these pathways, including neurodegeneration, are implicated in a variety of psychiatric and neurological diseases, such as schizophrenia, attention-deficit/hyperactivity disorder, drug addiction, and Parkinson disease. Based on the importance of the midbrain dopaminergic neurons to normal and pathological brain function, there is considerable interest in the molecular mechanisms that regulate their development. The goal of this short review is to outline new methods and recent advances in identifying the molecular networks that regulate midbrain dopaminergic neuron differentiation and fate. Midbrain dopaminergic neurons are descended from progenitor cells located near the ventral midline of the neural tube floor plate around the Cephalic Flexure. It is now clear that their initial formation is dependent on interactions between the signaling molecules Sonic hedgehog, WINGLESS 1, and FIBROBLAST growth factor 8, but there is still an extensive wider network of molecular interactions that must be resolved before the complete picture of dopaminergic neuron development can be described.
Thomas Gerster - One of the best experts on this subject based on the ideXlab platform.
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Regulatory gene expression patterns reveal transverse and longitudinal subdivisions of the embryonic zebrafish forebrain.
Mechanisms of Development, 2000Co-Authors: Giselbert Hauptmann, Thomas GersterAbstract:To shed light on the organization of the rostral embryonic brain of a lower vertebrate, we have directly compared the expression patterns of dlx, fgf, hh, hlx, otx, pax, POU, winged helix and wnt gene family members in the fore- and midbrain of the zebrafish. We show that the analyzed genes are expressed in distinct transverse and longitudinal domains and share expression boundaries at stereotypic positions within the fore- and midbrain. Some of these shared expression boundaries coincide with morphological landmarks like the pathways of primary axon tracts. We identified a series of eight transverse dienCephalic domains suggestive of neuromeric subdivisions within the rostral brain. In addition, we identified four molecularly distinct longitudinal subdivisions and provide evidence for a strong bending of the longitudinal rostral brain axis at the Cephalic Flexure. Our data suggest a strong conservation of early forebrain organization between lower and higher vertebrates.