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Rapid Shifts in the Temperature Dependence of Locomotor Performance in an Invasive Frog, Xenopus laevis , Implications for Conservation
Abstract Temperature is a critical abiotic factor impacting all aspects of the biology of organisms, especially in ectotherms. As such, it is an important determinant of the potential invasive ability of organisms and may limit population expansion unless organisms can physiologically respond to changes in temperature either through plasticity or by adapting to their novel environment. Here, we studied the African clawed frog, Xenopus laevis, which has become invasive on a global scale. We compared adults from an invasive population of western France with individuals from two populations in the native range in South Africa. We measured the thermal dependence of locomotor performance in adults given its relevance to dispersal, predator escape, and prey capture. Our results show significant differences in the limits of the 80% performance breadth interval for endurance with the French population showing a left shift in its limits congruent with the colder climate experienced in France. The French invasive population was introduced only about 40 years ago suggesting a rapid shift in the thermal physiology. Given that all individuals were acclimated under laboratory conditions at 23°C for 2 months this suggests that the invasive frogs have adapted to their new environment. These data may allow the refinement of physiologically informed species distribution models permitting better estimates of future ranges at risk of invasion.
Caveat mutator: alanine substitutions for conserved amino acids in RNA ligase elicit unexpected rearrangements of the active site for lysine adenylylation
Naegleria gruberi RNA ligase (NgrRnl) exemplifies the Rnl5 family of adenosine triphosphate (ATP)-dependent polynucleotide ligases that seal 3'-OH RNA strands in the context of 3'-OH/5'-PO 4 nicked duplexes. Like all classic ligases, NgrRnl forms a covalent lysyl–AMP intermediate. A two-metal mechanism of lysine adenylylation was established via a crystal structure of the NgrRnl•ATP•(Mn 2+ ) 2 Michaelis complex. Here we conducted an alanine scan of active site constituents that engage the ATP phosphates and the metal cofactors. We then determined crystal structures of ligase-defective NgrRnl-Ala mutants in complexes with ATP/Mn 2+ . The unexpected findings were that mutations K170A, E227A, K326A and R149A (none of which impacted overall enzyme structure) triggered adverse secondary changes in the active site entailing dislocations of the ATP phosphates, altered contacts to ATP, and variations in the numbers and positions of the metal ions that perverted the active sites into off-pathway states incompatible with lysine adenylylation. Each alanine mutation elicited a distinctive off-pathway distortion of the ligase active site. Our results illuminate a surprising plasticity of the ligase active site in its interactions with ATP and metals. More broadly, they underscore a valuable caveat when interpreting mutational data in the course of enzyme structure-function studies.
Pentatricopeptide repeats of protein-only RNase P use a distinct mode to recognize conserved bases and structural elements of pre-tRNA
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Critical point fluctuations: Finite size and global charge conservation effects
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Effects of local event-by-event conservation laws in ultrarelativistic heavy-ion collisions at particlization
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Higher order conserved charge fluctuations inside the mixed phase
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Particlization of an interacting hadron resonance gas with global conservation laws for event-by-event fluctuations in heavy-ion collisions
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Correcting event-by-event fluctuations in heavy-ion collisions for exact global conservation laws with the generalized subensemble acceptance method
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Conservation of B, S, and Q charges in relativistic viscous hydrodynamics solved with smoothed particle hydrodynamics
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Off-diagonal correlators of conserved charges from lattice QCD and how to relate them to experiment
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Gaussian null coordinates for rotating charged black holes and conserved charges
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Conservative tidal effects in compact binary systems to next-to-leading post-Minkowskian order
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Second order cumulants of conserved charge fluctuations revisited: Vanishing chemical potentials
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Dissipative magnetohydrodynamics for nonresistive relativistic plasmas: An implicit second-order flux-conservative formulation with stiff relaxation
Based on a 14-moment closure for nonresistive (general-) relativistic viscous plasmas, here we describe a new numerical scheme that is able to handle all first-order dissipative effects (heat conduction, bulk and shear viscosities), as well the anisotropies induced by the presence of magnetic fields. The latter is parametrized in terms of a thermal gyrofrequency or, equivalently, a thermal Larmor radius and allows to correctly capture the thermal Hall effect. By solving an extended Israel-Stewart-like system for the dissipative quantities that enforces algebraic constraints via stiff-relaxation, we are able to cast all first-order dissipative terms in flux-divergence form. This allows us to apply traditional high-resolution shock capturing methods to the equations, making the system suitable for the numerical study of highly turbulent flows. We present several numerical tests to assess the robustness of our numerical scheme in flat spacetime. The 14-moment closure can seamlessly interpolate between the highly collisional limit found in neutron star mergers, and the highly anisotropic limit of relativistic Braginskii magnetohydrodynamics appropriate for weakly collisional plasmas in black-hole accretion problems. We believe that this new formulation and numerical scheme will be useful for a broad class of relativistic magnetized flows.
Taylor expansions and Padé approximants for cumulants of conserved charge fluctuations at nonvanishing chemical potentials
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Conserved and nonconserved Noether currents from the quantum effective action
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