322,919 research outputs found
Sexually Diergic Trophic Effects of Estradiol Exposure on Developing Bovine Cerebellar Granule Cells
No full textIn the mammalian brain, the differentiation of neural cells and the developmental organization of the underlying circuitry are influenced by steroid hormones. The estrogen 17-β estradiol is one of the most potent regulators of neural growth during prenatal life, synthetized locally from steroid precursors including prenatal testicular testosterone. Estradiol promotes brain differentiation counting sexually dimorphic neural circuits by binding to the estrogen receptors, ER-α and ER-β. The cerebellum has been described as a site of estrogen action, and a potentially sexually dimorphic area. The goal of this study was to analyze the capacity of E2 to affect the growth of male and female fetal bovine cerebellar granule. We performed primary cultures of fetal cerebellar granules, and verified the mRNA expression of the ER-α and ER-β in both sexes. Moreover, the distribution of estrogen receptors in the male and female cerebellar granules of the second fetal stage was characterized by immunohistochemistry. We measured morphological parameters in presence (or absence) of estradiol administration, focusing on the variations of the dendritic branching pattern of granule neurons. By using the nonparametric combination and permutation testing approach, we proposed a sophisticated multivariate statistical analysis to demonstrate that E2 induces multifarious and dimorphic changes in the granule cells. E2 exerts trophic effects in both female and male granules and this effect is stronger in female. Male granules treated with E2 became similar to female control granule. Bos taurus species has a long gestation and a large brain that offers an interesting alternative in comparative neuroscience. © 2016 S. Karger AG, Basel Copyright © 2016, S. Karger AG. All rights reserved
The claustrum of the bottlenose dolphin Tursiops truncatus (Montagu 1821)
No full textThe mammalian claustrum is involved in processing sensory information from the environment. The claustrum is reciprocally connected to the visual cortex and these projections, at least in carnivores, display a clear retinotopic distribution. The visual cortex of dolphins occupies a position strikingly different from that of land mammals. Whether the reshaping of the functional areas of the cortex of cetaceans involves also modifications of the claustral projections remains hitherto unanswered. The present topographic and immunohistochemical study is based on the brains of eight bottlenose dolphins and a wide array of antisera against: calcium-binding proteins (CBPs) parvalbumin (PV), calretinin (CR), and calbindin (CB); somatostatin (SOM); neuropeptide Y (NPY); and the potential claustral marker Gng2. Our observations confirmed the general topography of the mammalian claustrum also in the bottlenose dolphin, although (a) the reduction of the piriform lobe modifies the ventral relationships of the claustrum with the cortex, and (b) the rotation of the telencephalon along the transverse axis, accompanied by the reduction of the antero-posterior length of the brain, apparently moves the claustrum more rostrally. We observed a strong presence of CR-immunoreactive (-ir) neurons and fibers, a diffuse but weak expression of CB-ir elements and virtually no PV immunostaining. This latter finding agrees with studies that report that PV-ir elements are rare in the visual cortex of the same species. NPY- and somatostatin-containing neurons were evident, while the potential claustral markers Gng2 was not identified in the sections, but no explanation for its absence is currently available. Although no data are available on the projections to and from the claustrum in cetaceans, our results suggest that its neurochemical organization is compatible with the presence of noteworthy cortical inputs and outputs and a persistent role in the general processing of the relative information. © 2014 Cozzi, Roncon, Granato, Giurisato, Castagna, Peruffo, Panin, Ballarin, Montelli and Pirone
Rapid continental break-up and microcontinent formation in the western Indian Ocean
No full textTwo of the main factors that determine the nature of a rifted continental margin are rheology and magmatism during extension. Numerical models of lithospheric extension suggest that both factors vary with extension rate; yet until now extension rates of studied margins, as indicated by the rate of initial seafloor spreading, are mostly less than -30 mm/yr on each margin. This article presents the first geophysical results from the Seychelles-Laxmi Ridge conjugate pair of rifted margins which separated at -65 mm/yr.
The Seychelles, with its spectacular exposures of Precambrian granite, was the earliest scientifically recognized microcontinent and arguably remains the classic example of one [Wegener, 1924; Matthews and Davies, 1966]. However, it is still unknown whether microcontinents result from plumes, changes in plate-boundary forces, lithospheric heterogeneity, or a combination of these factors
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
CHARACTERIZATION OF AN ESTABLISHED ENDOTHELIAL CELL LINE FROM PRIMARY CULTURES OF FETAL SHEEP HYPOTHALAMUS
No full textImmortalized cell lines from fetal brain are an experimental model for studying the in vitro molecular pathways regulating neural cell differentiation and the development of neural networks. The procedures are described to obtain an established cell line from the 90-day old fetal sheep hypothalamus. Viral oncogene LT-SV40 transformation was used to isolate a stable cell line (ENOS-01) that was characterized immunocytochemically. Immortalized cells can be classified as an endothelial cell line of hypothalamic microvasculature. Furthermore, mRNA expression and immunocytochemical of estrogen receptors α and β were also evaluated. Since it is known that cerebral vessels are directly targeted by sex steroids, our established cell line represents an alternative system to study estradiol/receptor interactions during brain development. Our in vitro model can provide a tool to investigate the complex relationships among the cell types forming the blood-brain barrier, which is known to be involved in the pathogenesis of sheep transmissible neurological diseases
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Expression and localization of aromatase P450AROM, estrogen receptor-α, and estrogen receptor-β in the developing fetal bovine frontal cortex
No full textThe enzyme aromatase (P450AROM) converts testosterone (T) into 17-b estradiol (E2) and is crucial for the
control of development of the central nervous system during ontogenesis. The effects of E2 in various
brain areas are mediated by the estrogen receptor alpha (ER-a) and the estrogen receptor beta (ER-b).
During fetal development, steroids are responsible for the sexual differentiation of the hypothalamus.
Estrogens are also able to exert effects in other brain areas of the fetus including the frontal cortex, where
they act through estrogen receptors (ERs) modulating cognitive function and affective behaviors.
In this study we have determined the expression profiles of P450AROM and ERs in the fetal bovine frontal
cortex by quantitative Real-Time PCR (qRT-PCR) throughout the prenatal development. The data show
that the patterns of expression of both ERs are strongly correlated during pregnancy and increase in the
last stage of gestation. On the contrary, the expression of P450AROM has no correlation with ERs expression
and is not developmentally regulated.
Moreover, we performed immunochemical studies showing that fetal neurons express P450AROM and
the ERs. P450AROM is localized in the cytoplasm and only seldom present in the fine extensions of the
cells; ER-a is detected predominantly in the soma whereas ER-b is only present in the nucleus of a
few cells. This study provides new data on the development of the frontal cortex in a long gestation mammal
with a large convoluted brain
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