2,730 research outputs found
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Leptodactylus cunicularius
Number of Pages: 5Integrative BiologyGeological Science
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Leptodactylus syphax
Number of Pages: 9Integrative BiologyGeological Science
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Leptodactylus savagei
Number of Pages: 19Integrative BiologyGeological Science
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Leptodactylus pentadactylus
Number of Pages: 48Integrative BiologyGeological Science
Density Induced Quantum Phase Transitions in Triplet Superconductors
We consider the possibility of quantum phase transitions in the ground state
of triplet superconductors where particle density is the tunning parameter. For
definiteness, we focus on the case of one band quasi-one-dimensional triplet
superconductors but many of our conclusions regarding the nature of the
transition are quite general. Within the functional integral formulation, we
calculate the electronic compressibility and superfluid density tensor as a
function of the particle density for various triplet order parameter symmetries
and find that these quantities are non-analytic when a critical value of the
particle density is reached.Comment: 4 pages, 3 figure
Evolution from BCS to BKT superfluidity in one-dimensional optical lattices
We analyze the finite temperature phase diagram of fermion mixtures in
one-dimensional optical lattices as a function of interaction strength. At low
temperatures, the system evolves from an anisotropic three-dimensional
Bardeen-Cooper-Schrieffer (BCS) superfluid to an effectively two-dimensional
Berezinskii-Kosterlitz-Thouless (BKT) superfluid as the interaction strength
increases. We calculate the critical temperature as a function of interaction
strength, and identify the region where the dimensional crossover occurs for a
specified optical lattice potential. Finally, we show that the dominant vortex
excitations near the critical temperature evolve from multiplane elliptical
vortex loops in the three-dimensional regime to planar vortex-antivortex pairs
in the two-dimensional regime, and we propose a detection scheme for these
excitations.Comment: 4 pages with 2 figure
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Asymmetry in Sexual Pheromones Is Not Required for Ascomycete Mating
Highlights
Asymmetric modification of pheromones is not required for yeast mating
Two yeast strains that express complementary pheromones and receptors mate with each other
Two yeast strains that express the same mating-type allele can mate with each other
Receptors and the pheromones determine the sexual identity of budding yeast
Summary
Background
We investigated the determinants of sexual identity in the budding yeast Saccharomyces cerevisiae. The higher fungi are divided into the ascomycetes and the basidiomycetes. Most ascomycetes have two mating types: one (called α in yeasts and MAT1-1 in filamentous fungi) produces a small, unmodified, peptide pheromone, and the other (a in yeasts and MAT1-2 in filamentous fungi) produces a peptide pheromone conjugated to a C-terminal farnesyl group that makes it very hydrophobic. In the basidiomycetes, all pheromones are lipid-modified, and this difference is a distinguishing feature between the phyla. We asked whether the asymmetry in pheromone modification is required for successful mating in ascomycetes.
Results
We cloned receptor and pheromone genes from a filamentous ascomycete and a basidiomycete and expressed these in the budding yeast, Saccharomyces cerevisiae, to generate novel, alternative mating pairs. We find that two yeast cells can mate even when both cells secrete a-like or α-like peptides. Importantly, this is true regardless of whether the cells express the a- or α-mating-type loci, which control the expression of other, sex-specific genes, in addition to the pheromones and pheromone receptors.
Conclusions
We demonstrate that the asymmetric pheromone modification is not required for successful mating of ascomycete fungi and confirm that, in budding yeast, the primary determinants of mating are the specificity of the receptors and their corresponding pheromones.Molecular and Cellular Biolog
Variation, Systematics, and Relationships of the Leptodactylus bolivianus Complex (Amphibia: Anura: Leptodactylidae)
Heyer, W. Ronald, and Rafael O. de Sá. Variation, Systematics, and Relationships of the Leptodactylus bolivianus Complex (Amphibia: Anura: Leptodactylidae). Smithsonian Contributions to Zoology, number 635, viii + 58 pages, 21 figures, 20 tables, 2011.—The Leptodactylus bolivianuscomplex has been considered to consist of one or two species, L. bolivianus alone or L. bolivianus and L. insularum. Detailed morphological analyses were undertaken to evaluate variation in the complex, which ranges from Costa Rica through Panama, across northern South America in the river valleys draining to the Caribbean, and throughout much of the Amazon basin with southern limits in Bolivia. Members of the complex also occur on several islands off Nicaragua, Panama, and Colombia. Analyses of morphological and advertisement call data indicate that there are either two or three species comprising the complex. Analysis of molecular data strongly supports recognition of three species, one of which is described as a new species, Leptodactylus guianensis. The three species comprising the L. bolivianus clade are most closely related to the L. ocellatus clade within the genus Leptodactylus
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