516 research outputs found
Farnesyl diphosphate synthase may determine the accumulation level of (â)-rotundone in 'Syrah' grapes
(â)-Rotundone is an oxygenated sesquiterpene responsible for the peppery aroma in grapes, wines, herbs, and spices, and it was first identified in 'Syrah' wine from Australia. In this study, we demonstrated the expression profiles of genes related to (â)-rotundone biosynthesis during the maturation of 'Syrah' grapes from two different vineyards, namely, the Iwaimura and Johnohira vineyards in Japan. The α-guaiene and (â)-rotundone accumulation levels in the grape exocarp from the Johnohira vineyard, which has a cool climatic condition located at a high altitude, were extremely higher than those from the Iwaimura vineyard. Among the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway genes, the transcript levels of 1-deoxy-D-xylulose-5-phosphate synthase gene (DXS) in the grape exocarp from the Johnohira vineyard were higher than those from the Iwaimura vineyard after vĂ©raison. The expression levels of the mevalonate pathway genes, Vitis vinifera terpene synthase gene (VvTPS24) and cytochrome P450 gene (CYP71BE5) in the final step of (â)-rotundone biosynthesis were not significantly different between samples from the two vineyards during grape maturation. In contrast, the farnesyl diphosphate synthase gene (FPPS) expression level was considerably higher in the grape exocarp from the Johnohira vineyard than in that from the Iwaimura vineyard. Consistent with these observations, FPPS was constantly expressed at higher level in 'Syrah' grape exocarp compared with 'Merlot' grape which is a low-rotundone cultivar. These findings suggest that FPPS may play a key role in determining the accumulation level of (â)-rotundone, which can provide abundant substrates for VvTPS24 catalysis to produce α-guaiene as a precursor of (â)-rotundone. In addition, among the MEP pathway genes, DXS may have a regulatory role for a precursor supply from the plastids to (â)-rotundone biosynthesis
First Record of \u3ci\u3eAgonostomus monticola\u3c/i\u3e (Family: Mugilidae) in Mississippi Freshwaters with Notes of its Distribution in the Southern United States
An individual of Agonostomus monticola (Mountain Mullet) was collected in southern Mississippi while conducting a series of community surveys on 7 November 2007. This is the first documented report of Mountain Mullet in Mississippi freshwaters, even though there are reports of three specimens collected in Mississippi estuarine waters in 1937. Given its life history and difficulties in sampling, it is likely that Mountain Mullet has a broader distribution and more frequently occurs in Gulf Coast drainages in the southern US than was previously thought
Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems
The Jovian regular satellite system mainly consists of four Galilean
satellites that have similar masses and are trapped in mutual mean motion
resonances except for the outer satellite, Callisto. On the other hand, the
Saturnian regular satellite system has only one big icy body, Titan, and a
population of much smaller icy moons. We have investigated the origin of these
major differences between the Jovian and Saturnian satellite systems by
semi-analytically simulating the growth and orbital migration of
proto-satellites in an accreting proto-satellite disk. We set up two different
disk evolution/structure models that correspond to Jovian and Saturnian
systems, by building upon previously developed models of an actively-supplied
proto-satellite disk, the formation of gas giants, and observations of young
stars. Our simulations extend previous models by including the (1) different
termination timescales of gas infall onto the proto-satellite disk and (2)
different evolution of a cavity in the disk, between the Jovian and Saturnian
systems. We have performed Monte Carlo simulations and show that in the case of
the Jovian systems, four to five similar-mass satellites are likely to remain
trapped in mean motion resonances. This orbital configuration is formed by type
I migration, temporal stopping of the migration near the disk inner edge, and
quick truncation of gas infall caused by Jupiter opening a gap in the Solar
nebula. The Saturnian systems tend to end up with one dominant body in the
outer regions caused by the slower decay of gas infall associated with global
depletion of the Solar nebula. The total mass and compositional zoning of the
predicted Jovian and Saturnian satellite systems are consistent with the
observed satellite systems.Comment: Accepted to ApJ, 33pages, 6figures, 2table
The growth and hydrodynamic collapse of a protoplanet envelope
We have conducted three-dimensional self-gravitating radiation hydrodynamical
models of gas accretion onto high mass cores (15-33 Earth masses) over hundreds
of orbits. Of these models, one case accretes more than a third of a Jupiter
mass of gas, before eventually undergoing a hydrodynamic collapse. This
collapse causes the density near the core to increase by more than an order of
magnitude, and the outer envelope to evolve into a circumplanetary disc. A
small reduction in the mass within the Hill radius (R_H) accompanies this
collapse as a shock propagates outwards. This collapse leads to a new
hydrostatic equilibrium for the protoplanetary envelope, at which point 97 per
cent of the mass contained within the Hill radius is within the inner 0.03 R_H
which had previously contained less than 40 per cent. Following this collapse
the protoplanet resumes accretion at its prior rate. The net flow of mass
towards this dense protoplanet is predominantly from high latitudes, whilst at
the outer edge of the circumplanetary disc there is net outflow of gas along
the midplane. We also find a turnover of gas deep within the bound envelope
that may be caused by the establishment of convection cells.Comment: 16 pages, 16 figures. Accepted for publication in MNRA
ESPRESSO Mass determination of TOI-263b: An extreme inhabitant of the brown dwarf desert
The TESS mission has reported a wealth of new planetary systems around bright
and nearby stars amenable for detailed characterization of the planet
properties and their atmospheres. However, not all interesting TESS planets
orbit around bright host stars. TOI-263b is a validated ultra-short period
substellar object in a 0.56-day orbit around a faint (V=18.97) M3.5 dwarf star.
The substellar nature of TOI-263b was explored using multi-color photometry,
which determined a true radius of 0.87+-0.21 Rj, establishing TOI-263b's nature
ranging from an inflated Neptune to a brown dwarf. The orbital period-radius
parameter space occupied by TOI-263b is quite unique, which prompted a further
characterization of its true nature. Here, we report radial velocity
measurements of TOI-263 obtained with 3 VLT units and the ESPRESSO spectrograph
to retrieve the mass of TOI-263b. We find that TOI-263b is a brown dwarf with a
mass of 61.6+-4.0 Mj. Additionally, the orbital period of the brown dwarf is
found to be synchronized with the rotation period of the host star, and the
system is found to be relatively active, possibly revealing a star--brown dwarf
interaction. All these findings suggest that the system's formation history
might be explained via disc fragmentation and later migration to close-in
orbits. If the system is found to be unstable, TOI-263 is an excellent target
to test the migration mechanisms before the brown dwarf becomes engulfed by its
parent star.Comment: Accepted for Publication in Astronomy and Astrophysic
Ariel planetary interiors White Paper
The recently adopted Ariel ESA mission will measure the atmospheric composition of a large number of exoplanets. This information will then be used to better constrain planetary bulk compositions. While the connection between the composition of a planetary atmosphere and the bulk interior is still being investigated, the combination of the atmospheric composition with the measured mass and radius of exoplanets will push the field of exoplanet characterisation to the next level, and provide new insights of the nature of planets in our galaxy. In this white paper, we outline the ongoing activities of the interior working group of the Ariel mission, and list the desirable theoretical developments as well as the challenges in linking planetary atmospheres, bulk composition and interior structure
Analysis of new high-precision transit light curves of WASP-10 b: starspot occultations, small planetary radius, and high metallicity
The WASP-10 planetary system is intriguing because different values of radius
have been reported for its transiting exoplanet. The host star exhibits
activity in terms of photometric variability, which is caused by the rotational
modulation of the spots. Moreover, a periodic modulation has been discovered in
transit timing of WASP-10 b, which could be a sign of an additional body
perturbing the orbital motion of the transiting planet. We attempt to refine
the physical parameters of the system, in particular the planetary radius,
which is crucial for studying the internal structure of the transiting planet.
We also determine new mid-transit times to confirm or refute observed anomalies
in transit timing. We acquired high-precision light curves for four transits of
WASP-10 b in 2010. Assuming various limb-darkening laws, we generated best-fit
models and redetermined parameters of the system. The prayer-bead method and
Monte Carlo simulations were used to derive error estimates. Three transit
light curves exhibit signatures of the occultations of dark spots by the planet
during its passage across the stellar disk. The influence of stellar activity
on transit depth is taken into account while determining system parameters. The
radius of WASP-10 b is found to be no greater than 1.03 Jupiter radii, a value
significantly smaller than most previous studies indicate. We calculate
interior structure models of the planet, assuming a two-layer structure with
one homogeneous envelope atop a rock core. The high value of the WASP-10 b's
mean density allows one to consider the planet's internal structure including
270 to 450 Earth masses of heavy elements. Our new mid-transit times confirm
that transit timing cannot be explained by a constant period if all literature
data points are considered. They are consistent with the ephemeris assuming a
periodic variation of transit timing...Comment: Accepted for publication in A&
Mutational Profile and Pathological Features of a Case of Interleukin-10 and RGS1-Positive Spindle Cell Variant Diffuse Large B-Cell Lymphoma
Diffuse large B-cell lymphoma with spindle cell morphology is a rare variant. We present the case of a 74-year-old male who initially presented with a right supraclavicular (lymph) node enlargement. Histological analysis showed a proliferation of spindle-shaped cells with narrow cytoplasms. An immunohistochemical panel was used to exclude other tumors, such as melanoma, carcinoma, and sarcoma. The lymphoma was characterized by a cell-of-origin subtype of germinal center B-cell-like (GCB) based on Hansâ classifier (CD10-negative, BCL6-positive, and MUM1-negative); EBER negativity, and the absence of BCL2, BCL6, and MYC rearrangements. Mutational profiling using a custom panel of 168 genes associated with aggressive B-cell lymphomas confirmed mutations in ACTB, ARID1B, DUSP2, DTX1, HLA-B, PTEN, and TNFRSF14. Based on the LymphGen 1.0 classification tool, this case had an ST2 subtype prediction. The immune microenvironment was characterized by moderate infiltration of M2-like tumor-associated macrophages (TMAs) with positivity of CD163, CSF1R, CD85A (LILRB3), and PD-L1; moderate PD-1 positive T cells, and low FOXP3 regulatory T lymphocytes (Tregs). Immunohistochemical expression of PTX3 and TNFRSF14 was absent. Interestingly, the lymphoma cells were positive for HLA-DP-DR, IL-10, and RGS1, which are markers associated with poor prognosis in DLBCL. The patient was treated with R-CHOP therapy, and achieved a metabolically complete response
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