9 research outputs found
Early Badenian transgression on the outer flank of Western Carpathian Foredeep, Hluchov area, Czech Republic
This
multidisciplinary
study, based on borehole cores from the Hluchov
area in Czech Republic,
docu-
ments
an early
Badenian
marine transgression on the outer flank of the Western Carpathian
Foredeep
. The
shallow-marine deposits represent coastal transgression over a terrestrial topography of weathered pre-Cenozoic
bedrock. The lower facies association (FA1) consists of
siliciclastic
sediment derived from local substrate erosion.
Facies indicate a wave-dominated environment with unstable bottom, variable rate of sediment supply and an
incremental rise of relative sea level. The upper facies association (FA2) consists of carbonates indicating a major
landward shift of shoreline, decline in
siliciclastic
input and further sea-level rise. The succession represents a
transgressive
to
highstand
systems tract.
The maximum flooding surface,
ca
. 1 m above the FA1/FA2 boundary, is signified by an anomalous decrease
in K and Th, an increased Th/K ratio and highest U concentration. The heavy-mineral assemblages in FA1 confirm
local sediment provenance, whereas those in FA2 indicate broader sediment derivation, including volcanic
component from contemporaneous
rhyolitic to
rhyodacitic
eruptions. The deposits contain a wide range of marine
fauna, with the foraminifers and molluscs indicating an early Badenian age. Molluscs, bryozoans and echinoderms
indicate a normal-salinity environment with a decreasing hydraulic energy. Foraminifers
indicate salinity
fluctua-
tions
in the lowest part of the succession. The isotopic composition of mollusc shells shows marked inter-species
differences and a general negative shift in the
d
13
C and
d
18
O values, indicating diagenetic
alteration. The impact
of diagenetic
processes appears to have been controlled by sedimentary facies. The highly negative
d
13
C and
d
18
O
values correspond to sediment layers with the highest Th/K ratios and hence low clay content. Sediment
permea-
bility
was thus probably crucial in controlling the differential circulation and impact of diagenetic
fluids
Cytoplasmic TAF2-TAF8-TAF10 complex provides evidence for nuclear holo-TFIID assembly from preformed submodules
General transcription factor TFIID is a cornerstone of RNA polymerase II transcription initiation in eukaryotic cells. How human TFIID-a megadalton-sized multiprotein complex composed of the TATA-binding protein (TBP) and 13 TBP-associated factors (TAFs)-assembles into a functional transcription factor is poorly understood. Here we describe a heterotrimeric TFIID subcomplex consisting of the TAF2, TAF8 and TAF10 proteins, which assembles in the cytoplasm. Using native mass spectrometry, we define the interactions between the TAFs and uncover a central role for TAF8 in nucleating the complex. X-ray crystallography reveals a non-canonical arrangement of the TAF8-TAF10 histone fold domains. TAF2 binds to multiple motifs within the TAF8 C-terminal region, and these interactions dictate TAF2 incorporation into a core-TFIID complex that exists in the nucleus. Our results provide evidence for a stepwise assembly pathway of nuclear holo-TFIID, regulated by nuclear import of preformed cytoplasmic submodules
Stable (H, O, C) and noble-gas (He and Ar) isotopic compositions from calcite and fluorite in the Speewah Dome, Kimberley Region, Western Australia: implications for the conditions of crystallization and evidence for the influence of crustal-mantle fluid mixing
In this study, the C-O-isotopic data from calcite at Yungul and Wilmott (Speewah. Western-Australia) are integrated with microthermometry, H2O-, CO2-content and H-He-Ar-isotopic data from fluid inclusions in genetically related calcite and fluorite to map the origin and crystallization paths of the fluids. In addition to the hydrogen isotopic compositions of fluid inclusions in fluorite, oxygen isotopic compositions were also determined by cavity ring-down spectroscopy. The geochemical data suggest mixing of a CO2-dominated mantle fluid and a H2O-domintated crustal brine. The fluid produced by this mixing is characterized by radiogenic (crustal-like) He-3/He-4 ratios, crustal-like dD values, relatively high salinity (19-24wt.% NaCl eq.), moderate homogenization temperatures (150-450 degrees C) and mantle-like CO2/He-3 ratios. Moreover, the large isotopic and elemental variations found in calcite indicate that its formation was accompanied by an extensive degassing (open system) leading to a decrease in dD and an increase in the CO2/He-3 values relative to the starting fluid composition. This degassing is consistent with the fluidal- and breccia-like texture of calcite observed in the field. In contrast, the fluorite which has coarse-grained banded to vughy textures formed in a passive aqueous system. Apparently the fluid that formed the fluorite has the same origin as the calcite, but the higher water content and the more radiogenic He-3/He-4 ratios reflect a greater involvement of crustal fluids. The historical description of the calcite-fluorite system in the Speewah area as "carbonatite" is now considered inappropriate because there is no evidence that crystallization is dominated by magmatic processes
Genesis of the Changba- Lijiagou giant Pb-Zn deposit, West Qinling, Central China: Constraints from S-Pb-C-O isotopes
Dolomite-bearing orogenic garnet peridotites witness fluid-mediated carbon recycling in a mantle wedge (Ulten Zone, Eastern Alps, Italy)
Histone propionylation is a mark of active chromatin
Histones are highly covalently modified, but the functions of many of these modifications remain unknown. In particular, it is unclear how histone marks are coupled to cellular metabolism and how this coupling affects chromatin architecture. We identified histone H3 Lys14 (H3K14) as a site of propionylation and butyrylation in vivo and carried out the first systematic characterization of histone propionylation. We found that H3K14pr and H3K14bu are deposited by histone acetyltransferases, are preferentially enriched at promoters of active genes and are recognized by acylation-state-specific reader proteins. In agreement with these findings, propionyl-CoA was able to stimulate transcription in an in vitro transcription system. Notably, genome-wide H3 acylation profiles were redefined following changes to the metabolic state, and deletion of the metabolic enzyme propionyl-CoA carboxylase altered global histone propionylation levels. We propose that histone propionylation, acetylation and butyrylation may act in combination to promote high transcriptional output and to couple cellular metabolism with chromatin structure and function