771 research outputs found
Phylotranscriptomic investigation into the evolution of endothermy in fish
Regional endothermy, where metabolically-derived heat is used to maintain elevated temperatures in parts of the body, has independently evolved in several lineages of pelagic, predatory fish, including billfish, tuna, lamnid sharks and the opah. The lamnid sharks and tunas demonstrate a striking phenotypic convergence, despite 450 million years of independent evolution. This is characterised by a distinctive muscle morphology, which has enabled them to utilise a unique stiff-bodied swimming style and maintain elevated muscular temperatures and metabolic capacities. This has facilitated expansions in thermal niche and increases in swimming speed and exercise recovery rate. We find selection has acted on one gene independently in both groups, glycogenin-1, which is associated with post-exercise glycogen replenishment. Different metabolic pathways have been targeted by selection in either group. Amongst the endothermic fish, there is considerable variability between species in endothermic capacity and cold-tolerance. By investigating diversification among the eight Thunnus tuna species, we find that the three highly cold-tolerant and endothermic bluefin tuna species are paraphyletic. We infer that parallel selection on ancestral genetic variation is likely to have enabled their evolution. This includes selection for variants in genes associated with metabolism and thermogenesis in other animals. Adaptations in the cardiac system of bluefin tuna are crucial to their ability to tolerate cold-water, as their heart operates at ambient temperature yet must supply oxygen for metabolically demanding warm muscle. We show that this elevated cardiac capacity is associated with increased expression of a key sarcoplasmic reticulum calcium-cycling gene, SERCA2b, in the atrium. Tuna muscle has a thermal gradient, with temperatures highest in the centre of the body. We found no upregulation of metabolic or thermogenesis genes in regions of warm muscle, indicating that intrinsic muscular contraction is sufficient for heat production. Our results provide insight into the genomic basis of endothermy in fish.Open Acces
Extensive genome introgression between domestic ferret and European polecat during population recovery in Great Britain.
peer reviewedThe European polecat (Mustela putorius) is a mammalian predator which occurs across much of Europe east to the Ural Mountains. In Great Britain, following years of persecution the European polecat has recently undergone a population increase due to legal protection and its range now overlaps that of feral domestic ferrets (Mustela putorius furo). During this range expansion, European polecats hybridised with feral domestic ferrets producing viable offspring. Here we carry out population-level whole genome sequencing on domestic ferrets, British European polecats, and European polecats from the European mainland and find high degrees of genome introgression in British polecats outside their previous stronghold, even in those individuals phenotyped as pure polecats. We quantify this introgression and find introgressed genes under selection that may assist in cognitive function and sight
Extensive genome introgression between domestic ferret and European polecat during population recovery in Great Britain
The European polecat (Mustela putorius) is a mammalian predator which occurs across much of Europe east to the Ural Mountains. In Great Britain, following years of persecution the range of the European polecat contracted and by the early 1900s was restricted to unmanaged forests of central Wales. The European polecat has recently undergone a population increase due to legal protection and its range now overlaps that of feral domestic ferrets (Mustela putorius furo). During this range expansion, European polecats hybridized with feral domestic ferrets producing viable offspring. Here, we carry out population-level whole-genome sequencing on 8 domestic ferrets, 19 British European polecats, and 15 European polecats from the European mainland. We used a range of population genomics methods to examine the data, including phylogenetics, phylogenetic graphs, model-based clustering, phylogenetic invariants, ABBA-BABA tests, topology weighting, and Fst. We found high degrees of genome introgression in British polecats outside their previous stronghold, even in those individuals phenotyped as "pure" polecats. These polecats ranged from presumed F1 hybrids (gamma = 0.53) to individuals that were much less introgressed (gamma = 0.2). We quantify this introgression and find introgressed genes containing Fst outliers associated with cognitive function and sight
Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires
The production of tt⟠, W+bb⟠and W+cc⟠is studied in the forward region of protonâproton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fbâ1 . The W bosons are reconstructed in the decays WââÎœ , where â denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of , and is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 0.02 \mbox{fb}^{-1}. The bosons are reconstructed in the decays , where denotes muon or electron, while the and quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions
Multidifferential study of identified charged hadron distributions in -tagged jets in proton-proton collisions at 13 TeV
Jet fragmentation functions are measured for the first time in proton-proton
collisions for charged pions, kaons, and protons within jets recoiling against
a boson. The charged-hadron distributions are studied longitudinally and
transversely to the jet direction for jets with transverse momentum 20 GeV and in the pseudorapidity range . The
data sample was collected with the LHCb experiment at a center-of-mass energy
of 13 TeV, corresponding to an integrated luminosity of 1.64 fb. Triple
differential distributions as a function of the hadron longitudinal momentum
fraction, hadron transverse momentum, and jet transverse momentum are also
measured for the first time. This helps constrain transverse-momentum-dependent
fragmentation functions. Differences in the shapes and magnitudes of the
measured distributions for the different hadron species provide insights into
the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb
public pages
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
Measurement of the ratios of branching fractions and
The ratios of branching fractions
and are measured, assuming isospin symmetry, using a
sample of proton-proton collision data corresponding to 3.0 fb of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The
tau lepton is identified in the decay mode
. The measured values are
and
, where the first uncertainty is
statistical and the second is systematic. The correlation between these
measurements is . Results are consistent with the current average
of these quantities and are at a combined 1.9 standard deviations from the
predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb
public pages
Phylotranscriptomic insights into the diversification of endothermic Thunnus tunas
Birds, mammals, and certain fishes, including tunas, opahs and lamnid sharks, are endothermic, conserving internally generated, metabolic heat to maintain body or tissue temperatures above that of the environment. Bluefin tunas are commercially important fishes worldwide, and some populations are threatened. They are renowned for their endothermy, maintaining elevated temperatures of the oxidative locomotor muscle, viscera, brain and eyes, and occupying cold, productive high-latitude waters. Less cold-tolerant tunas, such as yellowfin tuna, by contrast, remain in warm-temperate to tropical waters year-round, reproducing more rapidly than most temperate bluefin tuna populations, providing resiliency in the face of large-scale industrial fisheries. Despite the importance of these traits to not only fisheries but also habitat utilization and responses to climate change, little is known of the genetic processes underlying the diversification of tunas. In collecting and analyzing sequence data across 29,556 genes, we found that parallel selection on standing genetic variation is associated with the evolution of endothermy in bluefin tunas. This includes two shared substitutions in genes encoding glycerol-3 phosphate dehydrogenase, an enzyme that contributes to thermogenesis in bumblebees and mammals, as well as four genes involved in the Krebs cycle, oxidative phosphorylation, ÎČ-oxidation, and superoxide removal. Using phylogenetic techniques, we further illustrate that the eight Thunnus species are genetically distinct, but found evidence of mitochondrial genome introgression across two species. Phylogeny-based metrics highlight conservation needs for some of these species
Evidence of positive selection associated with placental loss in tiger sharks
Background: All vertebrates initially feed their offspring using yolk reserves. In some live-bearing species these yolk
reserves may be supplemented with extra nutrition via a placenta. Sharks belonging to the Carcharhinidae family
are all live-bearing, and with the exception of the tiger shark (Galeocerdo cuvier), develop placental connections
after exhausting yolk reserves. Phylogenetic relationships suggest the lack of placenta in tiger sharks is due to
secondary loss. This represents a dramatic shift in reproductive strategy, and is likely to have left a molecular
footprint of positive selection within the genome.
Results: We sequenced the transcriptome of the tiger shark and eight other live-bearing shark species. From this
data we constructed a time-calibrated phylogenetic tree estimating the tiger shark lineage diverged from the
placental carcharhinids approximately 94 million years ago. Along the tiger shark lineage, we identified five genes
exhibiting a signature of positive selection. Four of these genes have functions likely associated with brain
development (YWHAE and ARL6IP5) and sexual reproduction (VAMP4 and TCTEX1D2).
Conclusions: Our results indicate the loss of placenta in tiger sharks may be associated with subsequent adaptive
changes in brain development and sperm production
Measurement of the J/Ï pair production cross-section in pp collisions at TeV
The production cross-section of J/Ï pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of TeV, corresponding to an integrated luminosity of 279 ±11 pb. The measurement is performed for J/Ï mesons with a transverse momentum of less than 10 GeV/c in the rapidity range 2.0 < y < 4.5. The production cross-section is measured to be 15.2 ± 1.0 ± 0.9 nb. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/Ï pair are measured and compared to theoretical predictions.The production cross-section of pairs is measured using a data sample of collisions collected by the LHCb experiment at a centre-of-mass energy of , corresponding to an integrated luminosity of . The measurement is performed for mesons with a transverse momentum of less than in the rapidity range . The production cross-section is measured to be . The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the pair are measured and compared to theoretical predictions
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