Archive for the ‘researches 4’ Category
Sunday, March 16th, 2008
Evolution of a sensory novelty: Tympanic ears and the associated neural processing.
Tympanic hearing is a true evolutionary novelty that appears to have developed independently in at least five major tetrapod groups-the anurans, turtles, lepidosaurs, archosaurs and mammals. The emergence of a tympanic ear would have ...
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Sunday, March 16th, 2008
Vestibulotrigeminal pathways in the frog, Rana esculenta.
The aim of this study was to investigate whether primary vestibular afferent fibers establish direct connections with the motor and sensory trigeminal system in the brainstem of the frog. The experiments were carried out on Rana esculenta. In anaesthetized ...
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Sunday, March 16th, 2008
The visual system in subterranean African mole-rats (Rodentia, Bathyergidae): Retina, subcortical visual nuclei and primary visual cortex.
We have studied the visual system of subterranean mole-rats of the rodent family Bathyergidae, for which light and vision seem of little importance. The eye diameter varies between 3.5mm ...
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Sunday, March 16th, 2008
Developing a sense of scents: Plasticity in olfactory placode formation.
The sense organs of the vertebrate head arise predominantly from sensory placodes. The sensory placodes have traditionally been grouped as structures that share common developmental and evolutionary characteristics. In attempts to build a coherent model for ...
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Sunday, March 16th, 2008
Calcium-binding proteins label functional streams of the visual system in a songbird.
The vertebrate nervous system has been shown to contain high concentrations of intracellular calcium-binding proteins, each of them with a restricted expression pattern in specific brain regions and specific neuronal subpopulations. Using immunohistochemical staining ...
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Sunday, March 16th, 2008
The role of Pax genes in eye evolution.
Anatomically widely different designs of animal eyes have long been thought to arise independently multiple times during evolution. This morphology-based view has been challenged by the identification of a highly conserved transcription factor Pax6 that plays a key ...
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Sunday, March 16th, 2008
Does hair cell differentiation predate the vertebrate appearance?
It is generally accepted that the three main chordate groups (tunicates, cephalochordates and vertebrates) originated from a common ancestor having the basic features of the chordate body plan, i.e. a neural tube and a notochord flanked by striated ...
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Sunday, March 16th, 2008
Basic features of the ancestral chordate brain: A protochordate perspective.
Basic features of the anterior nerve cord in amphioxus larvae are summarized to highlight its essential similarity with the vertebrate brain. Except for a pineal homolog, the amphioxus brain consists of a much simplified version of ...
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Sunday, March 16th, 2008
Expression of the amphioxus Pit-1 gene (AmphiPOU1F1/Pit-1) exclusively in the developing preoral organ, a putative homolog of the vertebrate adenohypophysis.
For the Florida amphioxus (Branchiostoma floridae), the full-length sequence and developmental expression of AmphiPOU1F1/Pit-1 are described. This gene, which is present in a single copy in ...
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Sunday, March 16th, 2008
The brain in the early fossil jawless vertebrates: Evolutionary information from an empty nutshell.
Various 535-365 million year-old extinct jawless vertebrates taxa provide either direct or indirect information about brain and cranial nerve morphology. The paraphyletic group referred to as \"ostracoderms\", includes some forms in which ...
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Sunday, March 16th, 2008
Quantitative analysis of neural plate thickness and cell density during gastrulation in the chick embryo.
We quantitatively analyzed the developing prospective neural and non-neural ectoderm during chicken gastrulation on semithin transverse sections. At stage PS8 (primitive streak stage 8 of Lopez-Sanchez et al. [C. Lopez-Sanchez, L. ...
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Sunday, March 16th, 2008
Expression of cLhx6 and cLhx7/8 suggests a pallido-pedunculo-preoptic origin for the lateral and medial parts of the avian bed nucleus of the stria terminalis.
We investigated the origin of the avian bed nucleus of the stria terminalis (BST) and other parts of the avian subpallial amygdala, ...
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Sunday, March 16th, 2008
Implication of the Drosophila beta-amyloid peptide binding-like protein AMX in Notch signaling during early neurogenesis.
Lateral inhibition provides a mechanism to regulate neuroblast specification during early neurogenesis in Drososphila melanogaster embryos. This mechanism is mediated by the highly conserved Notch pathway. Defective lateral inhibition results in ...
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Sunday, March 16th, 2008
Early pretectal gene expression pattern shows a conserved anteroposterior tripartition in mouse and chicken.
A changing network of gene activity settles the molecular basis of regionalization in the nervous system. As a consequence, analysis of combined gene expressions patterns represents a powerful initial approach to decode ...
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Sunday, March 16th, 2008
Stage-specific effects of retinoic acid on gene expression during forebrain development.
Treatment of early gastrula- and neurula-staged Xenopus embryos with all-trans retinoic acid (RA) results in truncation of the anterior structures of the forebrain and head. The extent of truncation is dependent upon both the stage ...
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Sunday, March 16th, 2008
The particles of the embryonic cerebrospinal fluid: How could they influence brain development?
During brain development, the embryonic cerebrospinal fluid (E-CSF) allows brain expansion and promotes neuroepithelial cell survival, proliferation or differentiation. Previous analyses of E-CSF content have revealed a high protein concentration and the presence ...
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Sunday, March 16th, 2008
Synthesis of estrogens in progenitor cells of adult fish brain: Evolutive novelty or exaggeration of a more general mechanism implicating estrogens in neurogenesis?
In contrast to other vertebrates, in which the adult brain shows limited adult neurogenesis, teleost fishes exhibit an unparalleled capacity to generate new ...
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Sunday, March 16th, 2008
Identification of neural progenitor pools by E(Spl) factors in the embryonic and adult brain.
The maintenance of progenitor cells is a crucial aspect of central nervous system development and maturation, and bHLH transcription factors of the E(Spl) subfamily are involved in this process in all vertebrates ...
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Sunday, March 16th, 2008
Immunohistochemical localization of neuropeptide FF-like in the brain of the turtle: Relation to catecholaminergic structures.
A previous study in the lizard Gekko gecko has revealed that neuropeptide FF (NPFF, a neuropeptide involved in nociception, cardiovascular regulation, and endocrine function) is widely distributed throughout the brain and ...
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Sunday, March 16th, 2008
Distribution of adrenomedullin-like immunoreactivity in the brain of the adult sea lamprey.
Adrenomedullin (AM) is a neuropeptide widely distributed in vertebrates. In jawed vertebrates it has been localized in distinct regions of the central nervous system by means of antisera against human AM because the molecule ...
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Sunday, March 16th, 2008
The organization of the pretectal nuclei in the trout: A revision based on experimental holodogical studies.
The neuronal tracer DiI was applied to different brain centers of the rainbow trout in order to study the connections of pretectal nuclei. Our results showed that some pretectal nuclei ...
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Sunday, March 16th, 2008
Aspartate immunoreactivity in the telencephalon of the adult sea lamprey: Comparison with GABA immunoreactivity.
The excitatory amino acid l-aspartate (Asp) plays a number of roles in neuronal function. We studied the distribution of Asp-immunoreactive (ir) cells in the telencephalon of young and upstream migrating adult sea ...
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Sunday, March 16th, 2008
The segmental organization of the developing shark brain based on neurochemical markers, with special attention to the prosencephalon.
Brain regionalization has been extensively studied in tetrapods, teleosts and cyclostomes. In contrast, it has not been investigated in elasmobranchs, despite their key phylogenetic position to understand brain ...
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Sunday, March 16th, 2008
Anuran olfactory bulb organization: Embryology, neurochemistry and hodology.
In Xenopus laevis, we analyzed the origin of the projection neurons and interneurons in the developing olfactory bulbs by studying the expression patterns of the genes x-Eomes, x-Lhx5, x-Dll3 and x-Pax6. Olfactory bulb interneurons were characterized by using ...
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Sunday, March 16th, 2008
Conserved pattern of OTP-positive cells in the paraventricular nucleus and other hypothalamic sites of tetrapods.
The paraventricular nucleus complex (Pa) is a component of central neural circuitry that regulates several homeostatic variables. The paraventricular nucleus is composed of magnocellular neurons that project to the posterior pituitary ...
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