864 research outputs found
Crosstalk between Iron Metabolism and Erythropoiesis
Iron metabolism and erythropoiesis are inextricably linked. The majority of iron extracted from circulation daily is used for hemoglobin synthesis. In the last 15 years, major advances have been made in understanding the pathways regulating iron metabolism. Hepcidin is a key regulator of iron absorption and recycling and is itself regulated by erythropoiesis. While several viable candidates have been proposed, elucidating the “erythroid regulator” of hepcidin continues to generate significant experimental activity in the field. Although the mechanism responsible for sensing iron demand for erythropoiesis is still incompletely understood, evaluating diseases in which disordered erythropoiesis and/or iron metabolism are showcased has resulted in a more robust appreciation of potential candidates coordinated erythroid iron demand with regulators of iron supply. We present data drawn from four different conditions—iron deficiency, congenital hypotransferrinemia, beta-thalassemia, and hereditary hemochromatosis—both in human and non-human models of disease, together suggesting that erythroid iron demand exerts a stronger influence on circulating iron supply than systemic iron stores. Greater understanding of the interplay between the key factors involved in the regulation of iron metabolism and erythropoiesis will help develop more effective therapies for disorders of iron overload, iron deficiency, and hemoglobin synthesis
Toward an intensive understanding of sewer sediment prokaryotic community assembly and function
Prokaryotic communities play important roles in sewer sediment ecosystems, but the community composition, functional potential, and assembly mechanisms of sewer sediment prokaryotic communities are still poorly understood. Here, we studied the sediment prokaryotic communities in different urban functional areas (multifunctional, commercial, and residential areas) through 16S rRNA gene amplicon sequencing. Our results suggested that the compositions of prokaryotic communities varied significantly among functional areas. Desulfomicrobium, Desulfovibrio, and Desulfobacter involved in the sulfur cycle and some hydrolytic fermentation bacteria were enriched in multifunctional area, while Methanospirillum and Methanoregulaceae, which were related to methane metabolism were significantly discriminant taxa in the commercial area. Physicochemical properties were closely related to overall community changes (p < 0.001), especially the nutrient levels of sediments (i.e., total nitrogen and total phosphorus) and sediment pH. Network analysis revealed that the prokaryotic community network of the residential area sediment was more complex than the other functional areas, suggesting higher stability of the prokaryotic community in the residential area. Stochastic processes dominated the construction of the prokaryotic community. These results expand our understanding of the characteristics of prokaryotic communities in sewer sediment, providing a new perspective for studying sewer sediment prokaryotic community structure
Decreasing TfR1 expression reverses anemia and hepcidin suppression in β-thalassemic mice
Iron availability for erythropoiesis and its dysregulation in β-thalassemia are incompletely understood. We previously demonstrated that exogenous apotransferrin leads to more effective erythropoiesis, decreasing erythroferrone (ERFE) and derepressing hepcidin in β-thalassemic mice. Transferrin-bound iron binding to transferrin receptor 1 (TfR1) is essential for cellular iron delivery during erythropoiesis. We hypothesize that apotransferrin's effect is mediated via decreased TfR1 expression and evaluate TfR1 expression in β-thalassemic mice in vivo and in vitro with and without added apotransferrin. Our findings demonstrate that β-thalassemic erythroid precursors overexpress TfR1, an effect that can be reversed by the administration of exogenous apotransferrin. In vitro experiments demonstrate that apotransferrin inhibits TfR1 expression independent of erythropoietin- and iron-related signaling, decreases TfR1 partitioning to reticulocytes during enucleation, and enhances enucleation of defective β-thalassemic erythroid precursors. These findings strongly suggest that overexpressed TfR1 may play a regulatory role contributing to iron overload and anemia in β-thalassemic mice. To evaluate further, we crossed TfR1+/- mice, themselves exhibiting iron-restricted erythropoiesis with increased hepcidin, with β-thalassemic mice. Resultant double-heterozygote mice demonstrate long-term improvement in ineffective erythropoiesis, hepcidin derepression, and increased erythroid enucleation in relation to β-thalassemic mice. Our data demonstrate for the first time that TfR1+/- haploinsufficiency reverses iron overload specifically in β-thalassemic erythroid precursors. Taken together, decreasing TfR1 expression during β-thalassemic erythropoiesis, either directly via induced haploinsufficiency or via exogenous apotransferrin, decreases ineffective erythropoiesis and provides an endogenous mechanism to upregulate hepcidin, leading to sustained iron-restricted erythropoiesis and preventing systemic iron overload in β-thalassemic mice
Observation of and confirmation of its large branching fraction
The baryonic decay is observed, and the
corresponding branching fraction is measured to be
, where the first uncertainty is statistical
and second systematic. The data sample used in this analysis was collected with
the BESIII detector operating at the BEPCII double-ring collider with
a center-of-mass energy of 4.178~GeV and an integrated luminosity of
3.19~fb. The result confirms the previous measurement by the CLEO
Collaboration and is of greatly improved precision, which may deepen our
understanding of the dynamical enhancement of the W-annihilation topology in
the charmed meson decays
Observation and study of the decay
We report the observation and study of the decay
using events
collected with the BESIII detector. Its branching fraction, including all
possible intermediate states, is measured to be
. We also report evidence for a structure,
denoted as , in the mass spectrum in the GeV/
region. Using two decay modes of the meson ( and
), a simultaneous fit to the mass spectra is
performed. Assuming the quantum numbers of the to be , its
significance is found to be 4.4, with a mass and width of MeV/ and MeV, respectively, and a
product branching fraction
. Alternatively, assuming , the
significance is 3.8, with a mass and width of MeV/ and MeV, respectively, and a product
branching fraction
. The angular distribution of
is studied and the two assumptions of the
cannot be clearly distinguished due to the limited statistics. In all
measurements the first uncertainties are statistical and the second systematic.Comment: 10 pages, 6 figures and 4 table
Observation of in
Using a sample of events recorded with
the BESIII detector at the symmetric electron positron collider BEPCII, we
report the observation of the decay of the charmonium state
into a pair of mesons in the process
. The branching fraction is measured for the first
time to be , where the first uncertainty is
statistical, the second systematic and the third is from the uncertainty of
. The mass and width of the are
determined as MeV/ and
MeV.Comment: 13 pages, 6 figure
Evidence of a resonant structure in the cross section between 4.05 and 4.60 GeV
The cross section of the process for
center-of-mass energies from 4.05 to 4.60~GeV is measured precisely using data
samples collected with the BESIII detector operating at the BEPCII storage
ring.
Two enhancements are clearly visible in the cross section around 4.23 and
4.40~GeV.
Using several models to describe the dressed cross section yields stable
parameters for the first enhancement, which has a mass of 4228.6 \pm 4.1 \pm
6.3 \un{MeV}/c^2 and a width of 77.0 \pm 6.8 \pm 6.3 \un{MeV}, where the
first uncertainties are statistical and the second ones are systematic.
Our resonant mass is consistent with previous observations of the
state and the theoretical prediction of a molecule.
This result is the first observation of associated with an
open-charm final state.
Fits with three resonance functions with additional , ,
, , or a new resonance, do not show significant
contributions from either of these resonances. The second enhancement is not
from a single known resonance. It could contain contributions from
and other resonances, and a detailed amplitude analysis is required to better
understand this enhancement
First observations of hadrons
Based on events collected with
the BESIII detector, five hadronic decays are searched for via process
. Three of them, ,
, and are observed for the first
time, with statistical significances of 7.4, , and
9.1, and branching fractions of ,
, and ,
respectively, where the first uncertainties are statistical and the second
systematic. No significant signal is observed for the other two decay modes,
and the corresponding upper limits of the branching fractions are determined to
be and at 90% confidence level.Comment: 17 pages, 16 figure
Measurements of Weak Decay Asymmetries of , , , and
Using production from a 567 pb
data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried
out simultaneously on the four decay modes of , , , and . For the first time, the
transverse polarization is studied in unpolarized
collisions, where a non-zero effect is observed with a statistical significance
of 2.1. The decay asymmetry parameters of the weak
hadronic decays into , , and
are measured to be ,
,
, and
, respectively. In comparison with
previous results, the measurements for the and
modes are consistent but with improved precision, while the parameters for the
and modes are measured for the first time
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