Mantle Layer (mantle + layer)

Distribution by Scientific Domains

Selected Abstracts

The expression of Scratch genes in the developing and adult brain

Faustino Marín
Abstract The Scratch genes belong to the Snail superfamily of zinc-finger transcription factors present in the metazoa, represented in mammals by the Scratch1 and Scratch2 genes. We have analyzed the expression of these genes in the brain of mice at developmental stages between 9.5 days-post-coitum to adulthood. Both genes are expressed in the mantle layer of the neuroepithelium at mid-gestational stages in all regions except for the region corresponding to the V2 interneuron column, which lacked Scratch2 transcripts. From perinatal to adult stages, the expression patterns of the two genes differ. Scratch1 remains strongly expressed in almost all brain regions, although it is not found in some ventral structures such as motor nuclei and hypothalamic regions. In contrast, Scratch2 expression progressively diminishes and virtually no expression can be detected in the adult brain. Nevertheless, strong expression of Scratch2 is retained in the postnatal cortical subventricular zone, in the inner part of the cerebellar external granular layer, and in the glial cells of the adult vomeronasal nerve. Developmental Dynamoics 235:2586,2591, 2006. © 2006 Wiley-Liss, Inc. [source]

Ontogeny of tyrosine hydroxylase mRNA expression in mid- and forebrain: Neuromeric pattern and novel positive regions

Faustino Marín
Abstract Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the synthesis of catecholamines and, thus, critical in determining the catecholaminergic phenotype. In this study, we have examined the expression of TH mRNA by in situ hybridization in the embryonic mouse forebrain and midbrain and have mapped its localization according to the neuromeric pattern. We find that early in embryonic development, 10 to 12 days post coitum (dpc), TH mRNA is expressed in ample continuous regions of the neuroepithelium, extending across several neuromeres. However, from 12.5 dpc onward, the expression becomes restricted to discrete regions, which correspond to the dopaminergic nuclei (A8 to A15). In addition to these nuclei previously described, TH mRNA is also observed in regions that do not express this enzyme according to immunohistochemical studies. This difference in relation to protein expression pattern is consequent with the known posttranscriptional regulation of TH expression. The most representative example of a novel positive region is the conspicuous mRNA expression in both medial and lateral ganglionic eminences. This result agrees with reports describing the capacity of striatal stem cells (that is, located at the lateral ganglionic eminence) to become dopaminergic in vitro. Other regions include the isthmic mantle layer and the early floor plate of the midbrain,caudal forebrain. On the whole, the expression map we have obtained opens new perspectives for evolutionary/comparative studies, as well as for therapeutic approaches looking for potentially dopaminergic cells. Developmental Dynamics 234:709,717, 2005. © 2005 Wiley-Liss, Inc. [source]

Early and transient ontogenetic expression of the cocaine- and amphetamine-regulated transcript peptide in the rat mesencephalon: Correlation with tyrosine hydroxylase expression

F. Brischoux
Abstract The ontogeny of cocaine- and amphetamine-regulated transcript (CART) expression has been analyzed by immunohistochemistry in the mesencephalon of the rat central nervous system, and compared to the pattern of tyrosine hydroxylase- (TH-) expression. CART-producing neurons were first detected on the embryonic day 11 (E11) in the ventral mesencephalic vesicle. These neurons are among the first cells of the mantle layer to differentiate. From E13, a complementary pattern of distribution was observed, dividing the mantle layer into an external TH zone and an internal CART zone. Many TH-positive neurons were found to migrate from the neuroepithelium through the area containing the CART-immunoreactive neurons to settle more laterally. These TH cells exhibited prominent leading and trailing dendrites in the immediate vicinity of CART perikarya. On E16, the number of CART neurons appeared to diminish, and they were confined near the ventricle and around the fasciculus retroflexus. On E18 and E20, only the Edinger-Westphal nucleus exhibited a strong CART staining as described in the adult brain. Thus, the very early detection of CART during prenatal ontogeny led us to speculate that this peptide might have a role in the development of specific regions of the rat brain. In particular, our observations suggest that CART-expressing neurons might help the migration of the dopaminergic neurons of the substantia nigra. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 221,229, 2002 [source]

Embryonic gene expression and pro-protein processing of proSAAS during rodent development

Daniel J. Morgan
Abstract In vitro assays have demonstrated that peptides derived from the recently,identified proSAAS precursor inhibit prohormone convertase 1 (PC1) suggesting that this novel peptide may function as an endogenous inhibitor of PC1. To further understand the role of proSAAS in vivo, we have investigated the expression of proSAAS mRNA and processing of proSAAS during pre- and early postnatal rodent development. In situ hybridization showed that, by embryonic day 12.5 (e12.5) in the rat, proSAAS mRNA was present in essentially all differentiating neurons in the mantle layer of the myelencephalon, metencephalon, diencephalon, spinal cord and several sympathetic ganglia. During later stages of prenatal development, widespread proSAAS expression continues in post-mitotic neurons of both the CNS and PNS and begins in endocrine cells of the anterior and intermediate pituitary. Although proSAAS expression overlaps with PC1 in several regions, its overall expression pattern is significantly more extensive, suggesting that proSAAS may be multifunctional during development. Processed forms of proSAAS are present by at least mid-gestation with marked accumulation of two C-terminal forms, comprising the PC1 inhibitory fragment of proSAAS. [source]

Mycorrhizal synthesis between fungal strains of the Hymenoscyphus ericae aggregate and potential ectomycorrhizal and ericoid hosts

Trude Vrålstad
Summary ,,Fungal strains of the ,Hymenoscyphus ericae aggregate' (Helotiales, Ascomycota) were tested for their ability to form ecto-(ECM) and ericoid (ERM) mycorrhizas. ,,Twelve fungal test isolates were inoculated in vitro onto sterile ectomycorrhizal and ericoid host plants. ,,Five isolates of ectomycorrhizal origin formed ECM, three isolates of ericoid origin formed ERM, but none of the tested isolates was able to form both ECM and ERM. Confirmed ectomycorrhizal strains formed the characteristic black-and-hyaline mantles of the Piceirhiza bicolorata morphotype. This morphology represented an intermediate stage, where mantle-colour changed from light brown to black. The progressive darkening appeared to result from a gradual acropetal melanization of the outer mantle layer. ,,The synthesis results confirm that the ability to form both ecto- and ericoid mycorrhizal symbioses has evolved within the H. ericae aggregate. In addition, a phylogeny based on ITS1,5.8S,ITS2 rDNA sequences showed that the aggregate includes the ect(endo)mycorrhizal dark septate fungus Phialophora finlandia, grouping with four of the ECM-forming strains. The H. ericae aggregate therefore contains a number of closely related taxa with wide ecological attributes. [source]