331 research outputs found
Molecular evolution of cytochrome \u3ci\u3eb\u3c/i\u3e in high- and low-altitude deer mice (genus \u3ci\u3ePeromyscus\u3c/i\u3e)
Patterns of amino-acid polymorphism in human mitochondrial genes have been interpreted as evidence for divergent selection among populations that inhabit climatically distinct environments. If similar patterns are mirrored in other broadly distributed mammalian species, then adaptive modifications of mitochondrial protein function may be detected in comparisons among locally adapted populations of a single wide-ranging species, or among closely related species that have adapted to different environments. Here, we test for evidence of positive selection on cytochrome b variation within and among species of the ecologically diverse rodent genus Peromyscus. We used likelihood-based comparisons of synonymous and nonsynonymous substitution rates to test for evidence of divergent selection between high- and low-altitude haplogroups of the deer mouse, Peromyscus maniculatus. We also tested for evidence of divergent selection among different species of Peromyscus that inhabit different thermal environments. In contrast to the purported evidence for positive selection on mitochondrial proteins in humans and other nonhuman mammals, results of our tests suggest that the evolution of cytochrome b in Peromyscus is chiefly governed by purifying selection
Molecular evolution of cytochrome \u3ci\u3eb\u3c/i\u3e in high- and low-altitude deer mice (genus \u3ci\u3ePeromyscus\u3c/i\u3e)
Patterns of amino-acid polymorphism in human mitochondrial genes have been interpreted as evidence for divergent selection among populations that inhabit climatically distinct environments. If similar patterns are mirrored in other broadly distributed mammalian species, then adaptive modifications of mitochondrial protein function may be detected in comparisons among locally adapted populations of a single wide-ranging species, or among closely related species that have adapted to different environments. Here, we test for evidence of positive selection on cytochrome b variation within and among species of the ecologically diverse rodent genus Peromyscus. We used likelihood-based comparisons of synonymous and nonsynonymous substitution rates to test for evidence of divergent selection between high- and low-altitude haplogroups of the deer mouse, Peromyscus maniculatus. We also tested for evidence of divergent selection among different species of Peromyscus that inhabit different thermal environments. In contrast to the purported evidence for positive selection on mitochondrial proteins in humans and other nonhuman mammals, results of our tests suggest that the evolution of cytochrome b in Peromyscus is chiefly governed by purifying selection
Effect of the Coulomb repulsion on the {\it ac} transport through a quantum dot
We calculate in a linear response the admittance of a quantum dot out of
equilibrium. The interaction between two electrons with opposite spins
simultaneously residing on the resonant level is modeled by an Anderson
Hamiltonian. The electron correlations lead to the appearence of a new feature
in the frequency dependence of the conductance. For certain parameter values
there are two crossover frequencies between a capacitive and an inductive
behavior of the imaginary part of the admittance. The experimental implications
of the obtained results are briefly discussed.Comment: 13 pages, REVTEX 3.0, 2 .ps figures from [email protected],
NUB-308
Prevalence and Diversity of Avian Hematozoan Parasites in Asia: A Regional Study
Tissue samples from 699 birds from three regions of Asia (Myanmar, India, and South Korea) were screened for evidence of infection by avian parasites in the genera Plasmodium and Haemoproteus. Samples were collected from November 1994 to October 2004. We identified 241 infected birds (34.0%). Base-on-sequence data for the cytochrome b gene from 221 positive samples, 34 distinct lineages of Plasmodium, and 41 of Haemoproteus were detected. Parasite diversity was highest in Myanmar followed by India and South Korea. Parasite prevalence differed among regions but not among host families. There were four lineages of Plasmodium and one of Haemoproteus shared between Myanmar and India and only one lineage of Plasmodium shared between Myanmar and South Korea. No lineages were shared between India and South Korea, although an equal number of distinct lineages were recovered from each region. Migratory birds in South Korea and India originate from two different migratory flyways; therefore cross-transmission of parasite lineages may be less likely. India and Myanmar shared more host species and habitat types compared to South Korea. Comparison between low-elevation habitat in India and Myanmar showed a difference in prevalence of haematozoans
Battery data integrity and usability: Navigating datasets and equipment limitations for efficient and accurate research into battery aging
A tremendous commitment of resources is needed to acquire, understand and apply battery data in terms of performance and aging behavior. There are many state of performance (SOP) and state of health (SOH) metrics that are useful to guide alignment of batteries to end-use, yet how these metrics are measured or extracted can make the difference between usable, valuable datasets versus data that lacks the necessary integrity to meet baseline confidence levels for SOP/SOH quantification. This work will speak to 1) types of data that support SOP and SOH evaluations on mechanistic terms, 2) measurement conditions needed to assure high data integrity, 3) equipment limitations that can compromise data high fidelity, and 4) the impact of cell polarization on data quality. A common goal in battery research and field use is to work from a data platform that supports economical paths of data capture while minimizing down-time for battery diagnostics. An ideal situation would be to utilize data obtained during normal daily use (“pulses or cycles of convenience”) without stopping the daily duty cycles to perform dedicated SOP/SOH diagnostic routines. However, difficulties arise in trying to make use of daily duty cycle data (denoted as cycle-by-cycle, CBC) that underscores the need for standardization of conditions: temperature and duty cycles can vary over the course of a day and throughout a week, month and year; polarization can develop within an immediate cycle and throughout successive cycles as a hysteresis. If CBC data is envisioned as a data source to determine performance and aging trends, it should be recognized that polarization is a frequent consequence of CBC and thus makes it difficult to separate reversible and irreversible components to metrics such as capacity loss and resistance increase over aging. Since CBC conditions can have a major impact on data usability, we will devote part of this paper to CBC data conditioning and management. Differential analyses will also be discussed as a means to detect changing trends in data quality. Our target cell chemistries will be lithium-ion types NMC/graphite and LMO/LTO
Multimodal sensory reliance in the nocturnal homing of the amblypygid \u3ci\u3ePhrynus pseudoparvulus\u3c/i\u3e (Class Arachnida, Order Amblypygi)?
Like many other nocturnal arthropods, the amblypygid Phrynus pseudoparvulus is capable of homing. The environment through which these predators navigate is a dense and heterogeneous tropical forest understory and the mechanism(s) underlying their putatively complex navigational abilities are presently unknown. This study explores the sensory inputs that might facilitate nocturnal navigation in the amblypygid P. pseudoparvulus. Specifically, we use sensory system manipulations in conjunction with field displacements to examine the potential involvement of multimodal—olfactory and visual—stimuli in P. pseudoparvulus’ homing behavior. In a first experiment, we deprived individuals of their olfactory capacity and displaced them to the opposite side of their home trees (\u3c5 m). We found that olfaction-intact individuals were more likely to be re-sighted in their home refuges than olfaction-deprived individuals. In a second experiment, we independently manipulated both olfactory and visual sensory capacities in conjunction with longer-distance displacements (8 m) from home trees. We found that sensory-intact individuals tended to be re-sighted on their home tree more often than sensory-deprived individuals, with a stronger effect of olfactory deprivation than visual deprivation. Comparing across sensory modality manipulations, olfaction-manipulated individuals took longer to return to their home trees than vision-manipulated individuals. Together, our results indicate that olfaction is important in the nocturnal navigation of P. pseudoparvulus and suggest that vision may also play a more minor role
Localized High-Concentration Electrolytes Get More Localized Through Micelle-Like Structures
Liquid electrolytes in batteries are typically treated as macroscopically
homogeneous ionic transport media despite having complex chemical composition
and atomistic solvation structures, leaving a knowledge gap of microstructural
characteristics. Here, we reveal a unique micelle-like structure in a localized
high-concentration electrolyte (LHCE), in which the solvent acts as a
surfactant between an insoluble salt in diluent. The miscibility of the solvent
with the diluent and simultaneous solubility of the salt results in a
micelle-like structure with a smeared interface and an increased salt
concentration at the centre of the salt-solvent clusters that extends the salt
solubility. These intermingling miscibility effects have temperature
dependencies, wherein an exemplified LHCE peaks in localized cluster salt
concentration near room temperature and is utilized to form a stable
solid-electrolyte interphase (SEI) on Li-metal anode. These findings serve as a
guide to predicting a stable ternary phase diagram and connecting the
electrolyte microstructure with electrolyte formulation and formation protocols
to form stable SEI for enhanced battery cyclability
CONFIDENCE dissemination meeting: summary on the scenario-based workshop
The CONFIDENCE dissemination workshop “Coping with uncertainties for improved modelling and decision making in nuclear emergencies” was held in December 2–5, 2019 (Bratislava, Slovak Republic). About 90 scientists and decision makers attended the workshop. The dissemination workshop allowed the presentation of the CONFIDENCE project results, demonstration of the applicability of the developed methods and tools in interactive discussion sessions and the collection of feedback from the participants. The results were disseminated not only in the form of presentations and posters but also through interactive workshops where all participants were involved in round table working groups. A fictive accidental release scenario taking place at a nuclear power plant was developed and used by each work package in the workshop to provide the basis for interactive sessions and discussions
The “Ets” Factor: Vessel Formation in Zebrafish—The Missing Link?
The zebrafish offers a powerful model for studying the development of new blood vessels
Gfi1aa and Gfi1b set the pace for primitive erythroblast differentiation from hemangioblasts in the zebrafish embryo
The transcriptional repressors G
fi
1(a) and G
fi
1b are epigenetic regulators with unique and
overlapping roles in hematopoiesis. In different contexts, G
fi
1 and G
fi
1b restrict or promote
cell proliferation, prevent apoptosis, in
fl
uence cell fate decisions, and are essential for
terminal differentiation. Here, we show in primitive red blood cells (prRBCs) that they can
also set the pace for cellular differentiation. In zebra
fi
sh, prRBCs express 2 of 3 zebra
fi
sh G
fi
1/
1bparalogs,G
fi
1aaandG
fi
1b.Therecentlyidenti
fi
edzebra
fi
sh
gfi1aa
gene trap allele
qmc551
drives erythroid green
fl
uorescent protein (GFP) instead of G
fi
1aa expression, yet
homozygous carriers have normal prRBCs. prRBCs display a maturation defect only after
splice morpholino-mediated knockdown of G
fi
1b in
gfi1aa
qmc551
homozygous embryos. To study
the transcriptome of the G
fi
1aa/1b double-depleted cells, we performed an RNA-Seq experi-
ment on GFP-positive prRBCs sorted from 20-h
our-old embryos that were heterozygous or
homozygous for
gfi1aa
qmc551
,aswellas
wt
or morphant for
gfi1b
.Wesubsequentlycon
fi
rmed
and extended these data in whole-mount in situ hybridization experiments on newly generated
single- and double-mutant embryos. Combi
ned, the data showed that in the absence of G
fi
1aa,
the synchronously developing prRBCs were delayed
in activating late erythr
oid differentiation,
as they struggled to suppress early erythroid and
endothelial transcripti
on programs. The latter
highlighted the bipotent natu
re of the progenitors from which prRBCs arise. In the absence
of G
fi
1aa, G
fi
1b promoted erythroid differentiation as stepwise loss of
wt gfi1b
copies
progressively delayed G
fi
1aa-depleted prRBCs even
further, showing that G
fi
1aa and G
fi
1b
together set the pace for prRBC diffe
rentiation from hemangioblasts
- …