122 research outputs found
A major asymmetric ice trap in a planet-forming disk IV. Nitric oxide gas and a lack of CN tracing sublimating ices and a C/O ratio
[Abridged] Most well-resolved disks observed with ALMA show signs of dust
traps. These dust traps set the chemical composition of the planet forming
material in these disks, as the dust grains with their icy mantles are trapped
at specific radii and could deplete the gas and dust of volatiles at smaller
radii. In this work we analyse the first detection of nitric oxide (NO) in a
protoplanetary disk. We aim to constrain the nitrogen chemistry and the
gas-phase C/O ratio in the highly asymmetric dust trap in the Oph-IRS 48 disk.
We use ALMA observations of NO, CN, CH, and related molecules and model the
effect of the dust trap on the physical and chemical structure using the
thermochemical code DALI. Furthermore, we explore how ice sublimation
contributes to the observed emission lines. NO is only observed at the location
of the dust trap but CN and CH are not detected in the Oph-IRS 48 disk.
This results in an CN/NO column density ratio of and thus a low C/O
ratio at the location of the dust trap. The main gas-phase formation pathways
to NO through OH and NH in the fiducial model predict NO emission that is an
order of magnitude lower than is observed. The gaseous NO column density can be
increased by factors ranging from 2.8 to 10 when the HO and NH gas
abundances are significantly boosted by ice sublimation. However, these models
are inconsistent with the upper limits on the HO and OH column densities
derived from observations. We propose that the NO emission in the Oph-IRS 48
disk is closely related to the nitrogen containing ices sublimating in the dust
trap. The non-detection of CN constrains the C/O ratio both inside and outside
the dust trap to be if all nitrogen initially starts as N and , consistent with the Solar value, if (part of) the nitrogen initially
starts as N or NH.Comment: Accepted for publication in Astronomy and Astrophysic
JOYS+: mid-infrared detection of gas-phase SO emission in a low-mass protostar. The case of NGC 1333 IRAS2A: hot core or accretion shock?
JWST/MIRI has sharpened our infrared eyes toward the star formation process.
This paper presents the first mid-infrared detection of gaseous SO emission
in an embedded low-mass protostellar system. MIRI-MRS observations of the
low-mass protostellar binary NGC 1333 IRAS2A are presented from the JWST
Observations of Young protoStars (JOYS+) program, revealing emission from the
SO asymmetric stretching mode at 7.35 micron. The results are
compared to those derived from high-angular resolution SO data obtained
with ALMA. The SO emission from the band is predominantly located
on au scales around the main component of the binary, IRAS2A1. A
rotational temperature of K is derived from the lines. This is
in good agreement with the rotational temperature derived from pure rotational
lines in the vibrational ground state (i.e., ) with ALMA ( K).
However, the emission of the lines is not in LTE given that the total
number of molecules predicted by a LTE model is found to be a factor
higher than what is derived for the state. This
difference can be explained by a vibrational temperature that is K
higher than the derived rotational temperature of the state. The
brightness temperature derived from the continuum around the band of
SO is K, which confirms that the level is not
collisionally populated but rather infrared pumped by scattered radiation. This
is also consistent with the non-detection of the bending mode at 18-20
micron. Given the rotational temperature, the extent of the emission (
au in radius), and the narrow line widths in the ALMA data (3.5 km/s), the
SO in IRAS2A likely originates from ice sublimation in the central hot core
around the protostar rather than from an accretion shock at the disk-envelope
boundary.Comment: 19 pages, 17 figures, accepted for publication in A&A, abstract
abbreviate
Complex organic molecules in low-mass protostars on Solar System scales -- II. Nitrogen-bearing species
The chemical inventory of planets is determined by the physical and chemical
processes that govern the early phases of star formation. The aim is to
investigate N-bearing complex organic molecules towards two Class 0 protostars
(B1-c and S68N) at millimetre wavelengths with ALMA. Next, the results of the
detected N-bearing species are compared with those of O-bearing species for the
same and other sources. ALMA observations in Band 6 ( 1 mm) and Band 5
( 2 mm) are studied at 0.5" resolution, complemented by Band 3
( 3 mm) data in a 2.5" beam. NH2CHO, C2H5CN, HNCO, HN13CO, DNCO,
CH3CN, CH2DCN, and CHD2CN are identified towards the investigated sources.
Their abundances relative to CH3OH and HNCO are similar for the two sources,
with column densities that are typically an order of magnitude lower than those
of O-bearing species. The largest variations, of an order of magnitude, are
seen for NH2CHO abundance ratios with respect to HNCO and CH3OH and do not
correlate with the protostellar luminosity. In addition, within uncertainties,
the N-bearing species have similar excitation temperatures to those of
O-bearing species ( 100 300 K). The similarity of most abundances
with respect to HNCO, including those of CH2DCN and CHD2CN, hints at a shared
chemical history, especially the high D/H ratio in cold regions prior to star
formation. However, some of the variations in abundances may reflect the
sensitivity of the chemistry to local conditions such as temperature (e.g.
NH2CHO), while others may arise from differences in the emitting areas of the
molecules linked to their different binding energies in the ice. The two
sources discussed here add to the small number of sources with such a detailed
chemical analysis on Solar System scales. Future JWST data will allow a direct
comparison between the ice and gas abundances of N-bearing species.Comment: Accepted to A&A, 41 pages, 37 figure
Expression of survivin detected by immunohistochemistry in the cytoplasm and in the nucleus is associated with prognosis of leiomyosarcoma and synovial sarcoma patients
<p>Abstract</p> <p>Background</p> <p>Survivin, a member of the inhibitor of apoptosis-protein family suppresses apoptosis and regulates cell division. It is strongly overexpressed in the vast majority of cancers. We were interested if survivin detected by immunohistochemistry has prognostic relevance especially for patients of the two soft tissue sarcoma entities leiomyosarcoma and synovial sarcoma.</p> <p>Methods</p> <p>Tumors of leiomyosarcoma (n = 24) and synovial sarcoma patients (n = 26) were investigated for their expression of survivin by immunohistochemistry. Survivin expression was assessed in the cytoplasm and the nucleus of tumor cells using an immunoreactive scoring system (IRS).</p> <p>Results</p> <p>We detected a survivin expression (IRS > 2) in the cytoplasm of 20 leiomyosarcomas and 22 synovial sarcomas and in the nucleus of 12 leiomyosarcomas and 9 synovial sarcomas, respectively. There was no significant difference between leiomyosarcoma and synovial sarcoma samples in their cytoplasmic or nuclear expression of survivin. Next, all sarcoma patients were separated in four groups according to their survivin expression in the cytoplasm and in the nucleus: group 1: negative (IRS 0 to 2); group 2: weak (IRS 3 to 4); group 3: moderate (IRS 6 to 8); group 4: strong (IRS 9 to 12). In a multivariate Cox's regression hazard analysis survivin expression detected in the cytoplasm or in the nucleus was significantly associated with overall survival of patients in group 3 (RR = 5.7; P = 0.004 and RR = 5.7; P = 0.022, respectively) compared to group 2 (reference). Patients whose tumors showed both a moderate/strong expression of survivin in the cytoplasm and a moderate expression of survivin in the nucleus (in both compartments IRS ≥ 6) possessed a 24.8-fold increased risk of tumor-related death (P = 0.003) compared to patients with a weak expression of survivin both in the cytoplasm and in the nucleus.</p> <p>Conclusion</p> <p>Survivin protein expression in the cytoplasma and in the nucleus detected by immunohistochemistry is significantly associated with prognosis of leiomyosarcoma and synovial sarcoma patients.</p
Ifosfamide/etoposide alternating with high-dose methotrexate: evaluation of a chemotherapy regimen for poor-risk osteosarcoma
Fifteen patients with relapsed osteosarcoma were treated with an intensive combination chemotherapy schedule. Ifosfamide 2.5 g m−2 daily and etoposide 150 mg m−2 daily coincidentally for 3 days and high-dose methotrexate 8 g m−2 (with folinic acid rescue) on days 10–14 in a planned 21-day cycle. Feasibility, toxicity and response to this alternative combination for the treatment of relapsed osteosarcoma was assessed. There were 98 evaluable cycles for toxicity and tolerability. The majority of cycles were well tolerated. Haematological toxicity of grade 3/4 (common toxicity criteria) was seen in all courses. Renal tubular loss of electrolytes, particularly magnesium, occurred in 71% of cycles. Thirteen per cent of cycles were repeated within 21 days and 61% within 28 days. In the thirteen patients evaluable for response, a partial response rate of 31% was seen after two cycles. However, patients with stable disease continued on therapy, and an overall consequent response rate of 62% was observed. Four patients were alive with no evidence of disease at 8–74 months. Three are alive with disease (at 8–19 months). There were six deaths, all disease related. This regimen exhibits an encouraging response rate in a group of children with poor prognosis disease, with a tolerable toxicity profile. © 1999 Cancer Research Campaig
Additive QTLs on three chromosomes control flowering time in woodland strawberry (Fragaria vesca L.)
Flowering time is an important trait that affects survival, reproduction and yield in both wild and cultivated plants. Therefore, many studies have focused on the identification of flowering time quantitative trait locus (QTLs) in different crops, and molecular control of this trait has been extensively investigated in model species. Here we report the mapping of QTLs for flowering time and vegetative traits in a large woodland strawberry mapping population that was phenotyped both under field conditions and in a greenhouse after flower induction in the field. The greenhouse experiment revealed additive QTLs in three linkage groups (LG), two on both LG4 and LG7, and one on LG6 that explain about half of the flowering time variance in the population. Three of the QTLs were newly identified in this study, and one co-localized with the previously characterized FvTFL1 gene. An additional strong QTL corresponding to previously mapped PFRU was detected in both field and greenhouse experiments indicating that gene(s) in this locus can control the timing of flowering in different environments in addition to the duration of flowering and axillary bud differentiation to runners and branch crowns. Several putative flowering time genes were identified in these QTL regions that await functional validation. Our results indicate that a few major QTLs may control flowering time and axillary bud differentiation in strawberries. We suggest that the identification of causal genes in the diploid strawberry may enable fine tuning of flowering time and vegetative growth in the closely related octoploid cultivated strawberry.Peer reviewe
The Gene Ontology knowledgebase in 2023
The Gene Ontology (GO) knowledgebase (http://geneontology.org) is a comprehensive resource concerning the functions of genes and gene products (proteins and noncoding RNAs). GO annotations cover genes from organisms across the tree of life as well as viruses, though most gene function knowledge currently derives from experiments carried out in a relatively small number of model organisms. Here, we provide an updated overview of the GO knowledgebase, as well as the efforts of the broad, international consortium of scientists that develops, maintains, and updates the GO knowledgebase. The GO knowledgebase consists of three components: (1) the GO-a computational knowledge structure describing the functional characteristics of genes; (2) GO annotations-evidence-supported statements asserting that a specific gene product has a particular functional characteristic; and (3) GO Causal Activity Models (GO-CAMs)-mechanistic models of molecular "pathways" (GO biological processes) created by linking multiple GO annotations using defined relations. Each of these components is continually expanded, revised, and updated in response to newly published discoveries and receives extensive QA checks, reviews, and user feedback. For each of these components, we provide a description of the current contents, recent developments to keep the knowledgebase up to date with new discoveries, and guidance on how users can best make use of the data that we provide. We conclude with future directions for the project
The ζ Toxin Induces a Set of Protective Responses and Dormancy
The ζε module consists of a labile antitoxin protein, ε, which in dimer form (ε2) interferes with the action of the long-living monomeric ζ phosphotransferase toxin through protein complex formation. Toxin ζ, which inhibits cell wall biosynthesis and may be bactericide in nature, at or near physiological concentrations induces reversible cessation of Bacillus subtilis proliferation (protective dormancy) by targeting essential metabolic functions followed by propidium iodide (PI) staining in a fraction (20–30%) of the population and selects a subpopulation of cells that exhibit non-inheritable tolerance (1–5×10−5). Early after induction ζ toxin alters the expression of ∼78 genes, with the up-regulation of relA among them. RelA contributes to enforce toxin-induced dormancy. At later times, free active ζ decreases synthesis of macromolecules and releases intracellular K+. We propose that ζ toxin induces reversible protective dormancy and permeation to PI, and expression of ε2 antitoxin reverses these effects. At later times, toxin expression is followed by death of a small fraction (∼10%) of PI stained cells that exited earlier or did not enter into the dormant state. Recovery from stress leads to de novo synthesis of ε2 antitoxin, which blocks ATP binding by ζ toxin, thereby inhibiting its phosphotransferase activity
Diminishing benefits of urban living for children and adolescents’ growth and development
Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified
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