The Experts below are selected from a list of 177138 Experts worldwide ranked by ideXlab platform
Steven C Boyages - One of the best experts on this subject based on the ideXlab platform.
-
Detection of Extended Distribution of &-Thyroid Hormone Receptor Messenger Ribonucleic Acid (RNA) in Adult Rat Brain Using Complementary RNA in Situ
2008Co-Authors: Steven C BoyagesAbstract:In situ hybridization histochemistry using a complementary RNA probe, directed at the entire length of the thyroid hormone receptor & (TR&)-specific region (-56 to 495 bp), was used to evaluate expression of TR& messenger RNA (mRNA) in coronal sections of adult rat brain. An Extended Distribution and intense expression of TR& mRNA was found in several regions of rat brain, including regions where TRP, mRNA had not been previously identified using PCR or in situ hybridization histochemistry. These areas included hippocampus (dentate gyrus and Cl, -2, and -3), cerebral cortex (predominantly layer 3), arcuate nucleus, median eminence, medial geniculate nucleus, tegmental bundle, medial and lateral lemniscus, Purkinje layer of the cerebellum, and several brain stem nuclei. In conclusion, we have developed a highly sensitive and specific method to demonstrate TRP, mRNA expression in adult rat brain. The present findings are in agreement with immunoreactive TR& studies of rat brain and argue against the presence of an unidentified Ts-binding protein to explain the previous discordant results of TRPz mRNA and protein studies. In addition, the specificity of Distribution of TR& mRNA to certain brain nuclei, particularly those involved in hearing, implies a specific functional role of this receptor subtype and provides a physiological basis to understand the effects of hypothyroidism on brain development. (Endocrinology 137: 1272-1275, 1996)
-
Detection of Extended Distribution of beta2-thyroid hormone receptor messenger ribonucleic acid (RNA) in adult rat brain using complementary RNA in situ hybridization histochemistry.
Endocrinology, 1996Co-Authors: M Li, Steven C BoyagesAbstract:In situ hybridization histochemistry using a complementary RNA probe, directed at the entire length of the thyroid hormone receptor beta2 (TRbeta2)-specific region (-56 to 495 bp), was used to evaluate expression of TRbeta2 messenger RNA (mRNA) in coronal sections of adult rat brain. An Extended Distribution and intense expression of TRbeta2 mRNA was found in several regions of rat brain, including regions where TRbeta2 mRNA had not been previously identified using PCR or in situ hybridization histochemistry. These areas included hippocampus (dentate gyrus and C1, -2, and -3), cerebral cortex (predominantly layer 3), arcuate nucleus, median eminence, medial geniculate nucleus, tegmental bundle, medial and lateral lemniscus, Purkinje layer of the cerebellum, and several brain stem nuclei. In conclusion, we have developed a highly sensitive and specific method to demonstrate TRbeta2 mRNA expression in adult rat brain. The present findings are in agreement with immunoreactive TRbeta2 studies of rat brain and...
Beate Nurnberger - One of the best experts on this subject based on the ideXlab platform.
-
para allopatry in hybridizing fire bellied toads bombina bombina and b variegata inference from transcriptome wide coalescence analyses
Evolution, 2016Co-Authors: Beate Nurnberger, Konrad Lohse, Anna Fijarczyk, Jacek M Szymura, Mark BlaxterAbstract:Ancient origins, profound ecological divergence, and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Previous modeling has proposed that the narrow Bombina hybrid zones represent strong barriers to neutral introgression. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Krakow transect. We developed a method to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihood calculations. There was clear evidence for postdivergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended Distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
-
para allopatry in hybridizing fire bellied toads bombina bombina and b variegata inference from transcriptome wide coalescence analyses
bioRxiv, 2015Co-Authors: Beate Nurnberger, Konrad Lohse, Anna Fijarczyk, Jacek M Szymura, Mark BlaxterAbstract:Ancient origins, profound ecological divergence and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Narrow Bombina hybrid zones erect barriers to neutral introgression whose strength has been estimated previously. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Krakow transect. We developed a software pipeline to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihoods calculations. There was clear evidence for post-divergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended Distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
Mark Blaxter - One of the best experts on this subject based on the ideXlab platform.
-
para allopatry in hybridizing fire bellied toads bombina bombina and b variegata inference from transcriptome wide coalescence analyses
Evolution, 2016Co-Authors: Beate Nurnberger, Konrad Lohse, Anna Fijarczyk, Jacek M Szymura, Mark BlaxterAbstract:Ancient origins, profound ecological divergence, and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Previous modeling has proposed that the narrow Bombina hybrid zones represent strong barriers to neutral introgression. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Krakow transect. We developed a method to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihood calculations. There was clear evidence for postdivergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended Distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
-
para allopatry in hybridizing fire bellied toads bombina bombina and b variegata inference from transcriptome wide coalescence analyses
bioRxiv, 2015Co-Authors: Beate Nurnberger, Konrad Lohse, Anna Fijarczyk, Jacek M Szymura, Mark BlaxterAbstract:Ancient origins, profound ecological divergence and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Narrow Bombina hybrid zones erect barriers to neutral introgression whose strength has been estimated previously. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Krakow transect. We developed a software pipeline to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihoods calculations. There was clear evidence for post-divergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended Distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
James Binney - One of the best experts on this subject based on the ideXlab platform.
-
Chemodynamical modelling of the Milky Way
Astronomische Nachrichten, 2016Co-Authors: James Binney, Jason L. SandersAbstract:Chemodynamical models of our Galaxy that have analytic Extended Distribution Functions (EDFs) are likely to play a key role in extracting science from surveys in the era of Gaia.
-
characterizing stellar halo populations i an Extended Distribution function for halo k giants
Monthly Notices of the Royal Astronomical Society, 2016Co-Authors: Payel Das, James BinneyAbstract:We fit an Extended Distribution function (EDF) to K giants in the Sloan Extension for Galactic Understanding and Exploration survey. These stars are detected to radii ∼80 kpc and span a wide range in [Fe/H]. Our EDF, which depends on [Fe/H] in addition to actions, encodes the entanglement of metallicity with dynamics within the Galaxy's stellar halo. Our maximum-likelihood fit of the EDF to the data allows us to model the survey's selection function. The density profile of the K giants steepens with radius from a slope ∼−2 to ∼−4 at large radii. The halo's axis ratio increases with radius from 0.7 to almost unity. The metal-rich stars are more tightly confined in action space than the metal-poor stars and form a more flattened structure. A weak metallicity gradient ∼−0.001 dex kpc−1, a small gradient in the dispersion in [Fe/H] of ∼0.001 dex kpc−1, and a higher degree of radial anisotropy in metal-richer stars result. Lognormal components with peaks at ∼−1.5 and ∼−2.3 are required to capture the overall metallicity Distribution, suggestive of the existence of two populations of K giants. The spherical anisotropy parameter varies between 0.3 in the inner halo to isotropic in the outer halo. If the Sagittarius stream is included, a very similar model is found but with a stronger degree of radial anisotropy throughout.
-
Characterizing stellar halo populations – I. An Extended Distribution function for halo K giants
Monthly Notices of the Royal Astronomical Society, 2016Co-Authors: Payel Das, James BinneyAbstract:We fit an Extended Distribution function (EDF) to K giants in the Sloan Extension for Galactic Understanding and Exploration survey. These stars are detected to radii ∼80 kpc and span a wide range in [Fe/H]. Our EDF, which depends on [Fe/H] in addition to actions, encodes the entanglement of metallicity with dynamics within the Galaxy's stellar halo. Our maximum-likelihood fit of the EDF to the data allows us to model the survey's selection function. The density profile of the K giants steepens with radius from a slope ∼−2 to ∼−4 at large radii. The halo's axis ratio increases with radius from 0.7 to almost unity. The metal-rich stars are more tightly confined in action space than the metal-poor stars and form a more flattened structure. A weak metallicity gradient ∼−0.001 dex kpc−1, a small gradient in the dispersion in [Fe/H] of ∼0.001 dex kpc−1, and a higher degree of radial anisotropy in metal-richer stars result. Lognormal components with peaks at ∼−1.5 and ∼−2.3 are required to capture the overall metallicity Distribution, suggestive of the existence of two populations of K giants. The spherical anisotropy parameter varies between 0.3 in the inner halo to isotropic in the outer halo. If the Sagittarius stream is included, a very similar model is found but with a stronger degree of radial anisotropy throughout.
-
Extended Distribution functions for our Galaxy
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Jason L. Sanders, James BinneyAbstract:We extend models of our Galaxy based on Distribution functions (DFs) that are analytic functions of the action integrals to Extended Distribution functions (EDFs), which have an analytic dependence on metallicity as well. We use a simple, but physically-motivated, functional forms for the metallicity of the interstellar medium as a function of radius and time and for the star-formation rate, and a model for the diffusion of stars through phase space to suggest the required functional form of an EDF. We introduce a simple prescription for radial migration that preserves the overall profile of the disc while allowing individual stars to migrate throughout the disc. Our models explicitly consider the thin and thick discs as two distinct components separated in age. We show how an EDF can be used to incorporate realistic selection functions in models, and to construct mock catalogues of observed samples. We show that the selection function of the Geneva-Copenhagen Survey (GCS) biases in favour of young stars, which have atypically small random velocities. With the selection function taken into account our models produce good fits of the GCS data in chemo-dynamical space and the Gilmore and Reid (1983) density data. From our EDF, we predict the structure of the SEGUE G-dwarf sample. The kinematics are successfully predicted. The predicted metallicity Distribution has too few stars with [Fe/H]$\simeq-0.5$ dex and too many metal-rich stars. A significant problem may be the lack of any chemical-kinematic correlations in our thick disc. We argue that EDFs will prove essential tools for the analysis of both observational data and sophisticated models of Galaxy formation and evolution.
Anna Fijarczyk - One of the best experts on this subject based on the ideXlab platform.
-
para allopatry in hybridizing fire bellied toads bombina bombina and b variegata inference from transcriptome wide coalescence analyses
Evolution, 2016Co-Authors: Beate Nurnberger, Konrad Lohse, Anna Fijarczyk, Jacek M Szymura, Mark BlaxterAbstract:Ancient origins, profound ecological divergence, and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Previous modeling has proposed that the narrow Bombina hybrid zones represent strong barriers to neutral introgression. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Krakow transect. We developed a method to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihood calculations. There was clear evidence for postdivergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended Distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
-
para allopatry in hybridizing fire bellied toads bombina bombina and b variegata inference from transcriptome wide coalescence analyses
bioRxiv, 2015Co-Authors: Beate Nurnberger, Konrad Lohse, Anna Fijarczyk, Jacek M Szymura, Mark BlaxterAbstract:Ancient origins, profound ecological divergence and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Narrow Bombina hybrid zones erect barriers to neutral introgression whose strength has been estimated previously. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Krakow transect. We developed a software pipeline to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihoods calculations. There was clear evidence for post-divergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended Distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
