271 research outputs found
Calcium and magnesium absorption and retention by growing goats offered diets with different calcium sources
Calcium addition is necessary in order to balance the high phosphorus concentrations that are characteristic of high-concentrate ruminant diets. However, calcium sources differ in their bioavailability. Our objective was to determine apparent calcium and magnesium absorption and retention in goats offered diets containing different sources of calcium. Spanish-Boer goats (n = 18; 19.6 ± 1.88 kg) were stratified by body weight (BW) and sex and randomized to dietary treatments consisting of Purina Antlermax 16 containing either calcium carbonate (CC), Calmin (CM) or Milk Cal (MC). Goats were adapted to a control, corn-based high-concentrate diet on pasture and then moved to individual 1.0 × 1.5-m pens with plastic coated expanded metal floors, and adjusted to their respective diets along with removal of hay from the diet over a 7-d period. Goats were then offered their respective diets at a total of 2% of BW in equal feedings at 8:30 AM and 5:00 PM for an additional 14-d adaption period to diet and facilities followed by a 7-d collection of total urine and feces. Data were analyzed using PROC MIXED of SAS. Calcium and magnesium intake were not different (P ≥ 0.12) among diets. Calcium and magnesium apparent absorption and retention (g/d and % of intake) were greatest (P \u3c 0.05) in goats offered CC and did not differ (P ≥ 0.20) between goats offered the CM and MC diets. Therefore, calcium and magnesium were more available for goats from the diet containing calcium carbonate compared with diets containing Calmin and Milk Cal
APC mutations lead to cytokinetic failures in vitro and tetraploid genotypes in Min mice
Previous research has proposed that genomic instability contributes to cancer progression, with its initiation linked to tetraploid cell formation (Duesberg, P., and R. Li. 2003. Cell Cycle. 2:202–210; Ganem, N.J., Z. Storchova, and D. Pellman. 2007. Curr. Opin. Genet. Dev. 17:157–162). However, there is little direct evidence linking cancer-causing mutations with such events, and it remains controversial whether genomic instability is a cause or an effect of cancer. In this study, we show that adenomatous polyposis coli (APC) mutations found in human colorectal cancers dominantly inhibit cytokinesis by preventing mitotic spindle anchoring at the anaphase cortex and, thus, blocking initiation of the cytokinetic furrow. We find that dividing crypt cells in the small intestines of APCMin/+ mice exhibit similar mitotic defects, including misoriented spindles and misaligned chromosomes. These defects are observed in normal crypt cells with wild-type levels of β-catenin and, importantly, are associated with tetraploid genotypes. We provide direct evidence that the dominant activity of APC mutants induces aneuploidy in vivo. Our data support a model whereby tetraploid cells represent a first step in the onset of genomic instability and colorectal cancer
A Comparative Study on the Performance of Fiber-Based Biosorbents in the Purification of Biodiesel Derived from Camelina sativa
Biodiesel has received great interest as a promising substitute for petrodiesel. Biodiesel purification which follows the transesterification process is typically carried out using a wet washing process that generates large amounts of wastewater. Consequently, alternative methods are emerging as sustainable options for biodiesel purification. One of such methods is a dry washing process. In this paper, the performance of three dry washing media (commercially available BD-Zorb, sawdust and wood shavings) were evaluated as potentially suitable options for the purification of biodiesel derived from Camelina sativa. The results indicate that for the crude camelina biodiesel with an initial soap content of 9007 ppm, BD-Zorb exhibited the best purification performance. The soap removal capacity of BD-Zorb, sawdust, and wood shavings was 51.1 mL/g, 24.4 mL/g, and 9.4 mL/g respectively. The primary mechanism of soap removal using sawdust and wood shavings media was physical filtration and adsorption. While for adsorbent BD-Zorb, soap removal mechanism included adsorption and ion exchange due to the existence of a small amount of resins. The ion exchange led to a high acid number (1 mg KOH/g) of the purified biodiesel, and failed to meet the ASTM D6751 specifications (<0.5 mg KOH/g)
The survey of planetary nebulae in Andromeda (M31) III. Constraints from deep planetary nebula luminosity functions on the origin of the inner halo substructures in M31
The Andromeda (M31) galaxy displays several substructures in its inner halo
whose origin as remnants of accreted satellites or perturbations of the
pre-existing disc are encoded in the properties of their stellar populations
(SPs), leaving traces on their deep [OIII] 5007 \AA planetary nebulae
luminosity functions (PNLFs). By characterizing the morphology of the PNLFs, we
constrain their origin. From our 54 sq. deg. deep narrow-band [OIII] survey of
M31, we identify planetary nebulae (PNe) in the M31 disc and six major
inner-halo substructures - the Giant Stream, North East Shelf, G1-Clump,
Northern Clump, Western Shelf and Stream-D. We measure PNLF parameters from
cumulative fits and statistically compare the PNLFs in each substructure and
the disc. We link the PNLF parameters and those for the Large Magellanic Cloud
to published metallicities and age measurements for their parent SPs. The
absolute magnitudes of the PNLF bright cut-off () for these
sub-populations span a significant magnitude range, despite having similar
distance and line-of-sight extinction. for the Giant Stream, W-shelf
and Stream-D PNLFs are fainter than those predicted by PN evolution models for
the metallicity of the parent SPs. The faint-end slope of the PNLF increases
linearly with decreasing fraction of stellar mass younger than 5 Gyr across the
M31 regions and the LMC. From their PNLFs, the Giant Stream and NE-shelf are
consistent with being stellar debris from an infalling satellite, while the G1
Clump appears to be linked with the pre-merger disc. The SPs of the
substructures are consistent with those predicted by simulations of a single
massive merger event that took place 2--3 Gyr ago in M31. Stream-D has an
unrelated, distinct, origin. Furthermore, this study provides independent
evidence that the faint-end of the PNLF is preferentially populated by PNe
evolved from older stars.Comment: 14 pages, 7 figures, 4 tables; Abstract abridged; Accepted for
publication at Astronomy & Astrophysic
SDF1-A Facilitates Lin−/Sca1+ Cell Homing following Murine Experimental Cerebral Ischemia
Background
Hematopoietic stem cells mobilize to the peripheral circulation in response to stroke. However, the mechanism by which the brain initiates this mobilization is uncharacterized.
Methods
Animals underwent a murine intraluminal filament model of focal cerebral ischemia and the SDF1-A pathway was evaluated in a blinded manner via serum and brain SDF1-A level assessment, Lin−/Sca1+ cell mobilization quantification, and exogenous cell migration confirmation; all with or without SDF1-A blockade.
Results
Bone marrow demonstrated a significant increase in Lin−/Sca1+ cell counts at 24 hrs (272±60%; P<0.05 vs sham). Mobilization of Lin−/Sca1+ cells to blood was significantly elevated at 24 hrs (607±159%; P<0.05). Serum SDF1-A levels were significant at 24 hrs (Sham (103±14), 4 hrs (94±20%, p = NS) and 24 hrs (130±17; p<0.05)). Brain SDF1-A levels were significantly elevated at both 4 hrs and 24 hrs (113±7 pg/ml and 112±10 pg/ml, respectively; p<0.05 versus sham 76±11 pg/ml). Following administration of an SDF1-A antibody, Lin−/Sca1+ cells failed to mobilize to peripheral blood following stroke, despite continued up regulation in bone marrow (stroke bone marrow cell count: 536±65, blood cell count: 127±24; p<0.05 versus placebo). Exogenously administered Lin−/Sca1+ cells resulted in a significant reduction in infarct volume: 42±5% (stroke alone), versus 21±15% (Stroke+Lin−/Sca1+ cells), and administration of an SDF1-A antibody concomitant to exogenous administration of the Lin−/Sca1+ cells prevented this reduction. Following stroke, exogenously administered Lin−/Sca1+ FISH positive cells were significantly reduced when administered concomitant to an SDF1-A antibody as compared to without SDF1-A antibody (10±4 vs 0.7±1, p<0.05).
Conclusions
SDF1-A appears to play a critical role in modulating Lin−/Sca1+ cell migration to ischemic brain
The survey of planetary nebulae in Andromeda (M 31) V. Chemical enrichment of the thin and thicker discs of Andromeda. Oxygen to argon abundance ratios for planetary nebulae and H II regions
© M. Arnaboldi et al. 2022. This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.We use oxygen and argon abundances for planetary nebulae (PNe) with low internal extinction (progenitor ages of (>4.5 Gyr) and high extinction (progenitor agesPeer reviewe
The survey of planetary nebulae in Andromeda (M 31) V. Chemical enrichment of the thin and thicker discs of Andromeda. Oxygen to argon abundance ratios for planetary nebulae and H II regions
We use oxygen and argon abundances for planetary nebulae (PNe) with low
internal extinction (progenitor ages of (>4.5 Gyr) and high extinction
(progenitor ages <2.5 Gyr), as well as those of the H II regions, to constrain
the chemical enrichment and star formation efficiency in the thin and thicker
discs of M31. The argon element is produced in larger fraction by Type Ia
supernovae (SNe) than oxygen. We find that the mean log(O/Ar) values of PNe as
a function of their argon abundances, 12 + log(Ar/H), trace the inter-stellar
matter (ISM) conditions at the time of birth of the M 31 disc PN progenitors.
Thus the chemical enrichment and star formation efficiency information encoded
in the [alpha/Fe] vs. [Fe/H] distribution of stars is also imprinted in the
oxygen-to-argon abundance ratio log(O/Ar) vs. argon abundance for the nebular
emissions of the different stellar evolution phases. We propose to use the
log(O/Ar) vs. (12 + log(Ar/H)) distribution of PNe with different ages to
constrain the star-formation histories of the parent stellar populations in the
thin and thicker M31 discs. For the inner M31 disc (R_{GC} < 14 kpc), the
chemical evolution model that reproduces the mean log(O/Ar) values as function
of argon abundance for the high- and low-extinction PNe requires a second
infall of metal poorer gas during a gas-rich (wet) satellite merger. In M31,
the thin disc is younger and less radially extended, formed stars at a higher
star formation efficiency, and had a faster chemical enrichment timescale than
the more extended, thicker disc. Both the thin and thicker disc in M31 reach
similar high argon abundances ( 12 + log(Ar/H) ) ~ 6.7. The chemical and
structural properties of the thin/thicker discs in M31 are thus remarkably
different from those determined for the Milky Way thin and thick discs.Comment: 13 pages, 12 figures. Accepted for publication on 16.07.2022 in
Section 4. Extragalactic astronomy of Astronomy and Astrophysic
The Andromeda Galaxy’s Last Major Merger: Constraints from the survey of Planetary Nebulae
© 2023 International Astronomical Union.The Andromeda galaxy (M 31) has experienced a tumultuous merger history as evidenced by the many substructures present in its inner halo. We use planetary nebulae (PNe) as chemodynamic tracers to shed light on the recent merger history of M 31. We identify the older dynamically hotter thicker disc in M 31 and a distinct younger dynamically colder thin disc. The two discs are also chemically distinct with the PN chemodynamics implying their formation in a `wet' major merger (mass ratio ~1:5) ~2.5-4 Gyr ago. From comparison of PN line-of-sight velocities in the inner halo substructures with predictions of a major-merger model in M 31, we find that the same merger event that formed the M 31 thick and thin disc is also responsible for forming these substructures. We thereby obtain constraints on the recent formation history of M 31 and the properties of its cannibalized satellite
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