565 research outputs found
Перші християнські святині Києва: біля витоків національного державотворення
The low vigour of plantlets resulting from oil palm somatic embryos may be due to insufficient levels of deposited storage proteins. Thus, in order to improve embryonic maturation and the vigour of regenerated plantlets, we investigated the effects of modifying the culture conditions with respect to the accumulation of the major oil palm storage proteins, the 7S globulins. In this study, the effect of arginine and glutamine on globulin accumulation was studied using somatic embryos of two different genotypes. Arginine and glutamine were both found to enhance protein accumulation but in different ways, which were best illustrated by measurements of soluble proteins per embryo and 7S globulin content per dry weight. Arginine increased the level of soluble proteins by 46% irrespective of the clone, and glutamine by 19% and 63% depending on the clone. The clone which accumulated the least protein in the presence of glutamine was that which contained the more protein initially. Only arginine favoured the accumulation of 7S globulin content per dry weight, irrespective of the clone considered (+26%). This study will enable further investigations of specific storage proteins as potential markers for regenerated plantlets vigour.(Résumé d'auteur
Supersymmetric structure of the induced W gravities
We derive the supersymmetric structure present in W-gravities which has been
already observed in various contexts as Yang-Mills theory, topological field
theories, bosonic string and chiral W_{3}-gravity. This derivation which is
made in the geometrical framework of Zucchini, necessitates the introduction of
an appropriate new basis of variables which replace the canonical fields and
their derivatives. This construction is used, in the W_{2}-case, to deduce from
the Chern-Simons action the Wess-Zumino-Polyakov action.Comment: 17 pages, Latex. To appear in Class. Quantum. Gravit
Daily transcriptomes of the copepod Calanus finmarchicus during the summer solstice at high Arctic latitudes
The zooplankter Calanus finmarchicus is a member of the so-called “Calanus Complex”, a group of
copepods that constitutes a key element of the Arctic polar marine ecosystem, providing a crucial
link between primary production and higher trophic levels. Climate change induces the shift of C.
finmarchicus to higher latitudes with currently unknown impacts on its endogenous timing. Here we
generated a daily transcriptome of C. finmarchicus at two high Arctic stations, during the more extreme
time of Midnight Sun, the summer solstice. While the southern station (74.5 °N) was sea ice-free, the
northern one (82.5 °N) was sea ice-covered. The mRNAs of the 42 samples have been sequenced with an
average of 126 ± 5 million reads (mean ± SE) per sample, and aligned to the reference transcriptome.
We detail the quality assessment of the datasets and the complete annotation procedure, providing
the possibility to investigate daily gene expression of this ecologically important species at high Arctic
latitudes, and to compare gene expression according to latitude and sea ice-coverage
Ozone comparison between Pandora #34, Dobson #061, OMI, and OMPS in Boulder, Colorado, for the period December 2013–December 2016
A one-time-calibrated (in December 2013) Pandora spectrometer instrument (Pan
#034) has been compared to a periodically calibrated Dobson
spectroradiometer (Dobson #061) co-located in Boulder, Colorado, and
compared with two satellite instruments over a 3-year period (December
2013–December 2016). The results show good agreement between Pan #034 and
Dobson #061 within their statistical uncertainties. Both records are
corrected for ozone retrieval sensitivity to stratospheric temperature
variability obtained from the Global Modeling Initiative (GMI) and Modern-Era
Retrospective analysis for Research and Applications (MERRA-2) model
calculations. Pandora #034 and Dobson #061 differ by an average of
2.1 ± 3.2 % when both instruments use their standard ozone
absorption cross sections in the retrieval algorithms. The results show a
relative drift (0.2 ± 0.08 % yr−1) between Pandora
observations against NOAA Dobson in Boulder, CO, over a 3-year period of
continuous operation. Pandora drifts relative to the satellite Ozone
Monitoring Instrument (OMI) and the Ozone Mapping Profiler Suite (OMPS) are
+0.18 ± 0.2 % yr−1 and −0.18 ± 0.2 % yr−1,
respectively, where the uncertainties are 2 standard deviations. The drift
between Dobson #061 and OMPS for a 5.5-year period (January 2012–June 2017) is −0.07 ± 0.06 % yr−1
White-gutted soldiers: simplification of the digestive tube for a non-particulate diet in higher Old World termites (Isoptera: Termitidae)
Previous observations have noted that in some species of higher termites the soldier caste lacks pigmented particles in its gut and, instead, is fed worker saliva that imparts a whitish coloration to the abdomen. In order to investigate the occurrence of this trait more thoroughly, we surveyed a broad diversity of termite specimens and taxonomic descriptions from the Old World subfamilies Apicotermitinae, Cubitermitinae, Foraminitermitinae, Macrotermitinae, and Termitinae. We identified 38 genera that have this “white-gutted” soldier (WGS) trait. No termite soldiers from the New World were found to possess a WGS caste. Externally, the WGS is characterized by a uniformly pale abdomen, hyaline gut, and proportionally smaller body-to-head volume ratio compared with their “dark-gutted” soldier (DGS) counterparts found in most termitid genera. The WGS is a fully formed soldier that, unlike soldiers in other higher termite taxa, has a small, narrow, and decompartmentalized digestive tube that lacks particulate food contents. The presumed saliva-nourished WGS have various forms of simplified gut morphologies that have evolved at least six times within the higher termites
The conserved C-terminus of the PcrA/UvrD helicase interacts directly with RNA polymerase
Copyright: © 2013 Gwynn et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by a Wellcome Trust project grant to MD (Reference: 077368), an ERC starting grant to MD (Acronym: SM-DNA-REPAIR) and a BBSRC project grant to PM, NS and MD (Reference: BB/I003142/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
The galaxy mass-size relation in CARLA clusters and proto-clusters at 1.4 < z < 2.8: larger cluster galaxy sizes
(Abridged) We study the galaxy mass-size relation in CARLA spectroscopically
confirmed clusters at , which span a total stellar mass
(halo mass ). Our main finding is that cluster
passive ETG at with are
systematically larger than field ETGs. The passive
ETG average size evolution is slower at when compared to the field.
This could be explained by differences in the formation and early evolution of
galaxies in haloes of a different mass. Strong compaction and gas dissipation
in field galaxies, followed by a sequence of mergers may have also played a
significant role in the field ETG evolution, but not in the evolution of
cluster galaxies. Our passive ETG mass-size relation shows a tendency to
flatten at , where the average size is
. This implies that galaxies in
the low end of the mass-size relation do not evolve much from to the
present, and that their sizes evolve in a similar way in clusters and in the
field. BCGs lie on the same mass-size relation as satellites, suggesting that
their size evolution is not different at redshift z 2. Half of the
active ETGs ( of the ETGs) follow the field passive galaxy mass-size
relation, and the other half follow the field active galaxy mass-size relation.
These galaxies likely went through a recent merger or neighbor galaxy
interaction, and would most probably quench at a later epoch and increase the
fraction of passive ETGs in clusters. We do not observe a large population of
compact galaxies, as is observed in the field at these redshifts, implying that
the galaxies in our clusters are not observed in an epoch close to their
compaction.Comment: 15 pages, 10 figures, accepted for publication in Astronomy &
Astrophysic
DNA cruciform arms nucleate through a correlated but non-synchronous cooperative mechanism
Inverted repeat (IR) sequences in DNA can form non-canonical cruciform
structures to relieve torsional stress. We use Monte Carlo simulations of a
recently developed coarse-grained model of DNA to demonstrate that the
nucleation of a cruciform can proceed through a cooperative mechanism. Firstly,
a twist-induced denaturation bubble must diffuse so that its midpoint is near
the centre of symmetry of the IR sequence. Secondly, bubble fluctuations must
be large enough to allow one of the arms to form a small number of hairpin
bonds. Once the first arm is partially formed, the second arm can rapidly grow
to a similar size. Because bubbles can twist back on themselves, they need
considerably fewer bases to resolve torsional stress than the final cruciform
state does. The initially stabilised cruciform therefore continues to grow,
which typically proceeds synchronously, reminiscent of the S-type mechanism of
cruciform formation. By using umbrella sampling techniques we calculate, for
different temperatures and superhelical densities, the free energy as a
function of the number of bonds in each cruciform along the correlated but
non-synchronous nucleation pathways we observed in direct simulations.Comment: 12 pages main paper + 11 pages supplementary dat
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