894 research outputs found
Calcium/calmodulin-dependent kinases can regulate the TSH expression in the rat pituitary.
PURPOSE: The endocrine secretion of TSH is a finely orchestrated process
controlled by the thyrotropin-releasing hormone (TRH). Its homeostasis and
signaling rely on many calcium-binding proteins belonging to the "EF-hand"
protein family. The Ca2+/calmodulin (CaM) complex is associated with
Ca2+/CaM-dependent kinases (Ca2+/CaMK). We have investigated Ca2+/CaMK
expression and regulation in the rat pituitary.
METHODS: The expression of CaMKII and CaMKIV in rat anterior pituitary cells was
shown by immunohistochemistry. Cultured anterior pituitary cells were stimulated
by TRH in the presence and absence of KN93, the pharmacological inhibitor of
CaMKII and CaMKIV. Western blotting was then used to measure the expression of
these kinases and of the cAMP response element-binding protein (CREB). TSH
production was measured by RIA after time-dependent stimulation with TRH. Cells
were infected with a lentiviral construct coding for CaMKIV followed by
measurement of CREB phosphorylation and TSH.
RESULTS: Our study shows that two CaM kinases, CaMKII and CaMKII, are expressed
in rat pituitary cells and their phosphorylation in response to TRH occurs at
different time points, with CaMKIV being activated earlier than CaMKII. TRH
induces CREB phosphorylation through the activity of both CaMKII and CaMKIV. The
activation of CREB increases TSH gene expression. CaMKIV induces CREB
phosphorylation while its dominant negative and KN93 exert the opposite effects.
CONCLUSION: Our data indicate that the expression of Ca2+/CaMK in rat anterior
pituitary are correlated to the role of CREB in the genetic regulation of TSH,
and that TRH stimulation activates CaMKIV, which in turn phosphorylates CREB.
This phosphorylation is linked to the production of thyrotropin
Production of Succinic Acid From Basfia succiniciproducens
Basfia succiniciproducens is a facultative anaerobic capnophilic bacterium, isolated
from rumen, that naturally produces high amounts of succinic acid by fixing CO2 and
using fumarate as final electron acceptor. This metabolic feature makes it one of the
ideal candidates for developing biotechnological industrial routes that could
eventually replace the polluting and environment unfriendly petrochemical ones
that are still main sources for the production of this value-added compound. In
fact, due to the large number of applications of succinic acid that range from the more
traditional ones as food additive or pharmaceutical intermediate to the most recent as
building block for biopolymers and bioplastic, increasing demand and market size growth
are expected in the next years. In line with a âgreen revolutionâ needed to preserve our
environment, the great challenge is the establishment of commercially viable production
processes that exploit renewable materials and in particular preferably non-food
lignocellulosic biomasses and waste products. In this review, we describe the currently
available literature concerning B. succiniciproducens since the strain was first isolated,
focusing on the different renewable materials and fermentation strategies used to improve
succinic acid production titers to date. Moreover, an insight into the metabolic engineering
approaches and the key physiological characteristics of B. succiniciproducens deduced
from the different studies are presented
Combining Microwave Radiometer and Wind Profiler Radar Measurements for High-Resolution Atmospheric Humidity Profiling
Abstract
A self-consistent remote sensing physical method to retrieve atmospheric humidity high-resolution profiles by synergetic use of a microwave radiometer profiler (MWRP) and wind profiler radar (WPR) is illustrated. The proposed technique is based on the processing of WPR data for estimating the potential refractivity gradient profiles and their optimal combination with MWRP estimates of potential temperature profiles in order to fully retrieve humidity gradient profiles. The combined algorithm makes use of recent developments in WPR signal processing, computing the zeroth-, first-, and second-order moments of WPR Doppler spectra via a fuzzy logic method, which provides quality control of radar data in the spectral domain. On the other hand, the application of neural network to brightness temperatures, measured by a multichannel MWRP, can provide continuous estimates of tropospheric temperature and humidity profiles. Performance of the combined algorithm in retrieving humidity profiles is compared with simultaneous in situ radiosonde observations (raob's). The empirical sets of WPR and MWRP data were collected at the Atmospheric Radiation Measurement (ARM) Program's Southern Great Plains (SGP) site. Combined microwave radiometer and wind profiler measurements show encouraging results and significantly improve the spatial vertical resolution of atmospheric humidity profiles. Finally, some of the limitations found in the use of this technique and possible future improvements are also discussed
A statistical study of the Stromboli volcano explosion quakes before and during 2002-2003 eruptive crisis
We study the seismic wavefield and the statistical properties of the Stromboli volcano
explosions preceding and during the 2002â2003 crisis. We analyze the recordings of a
threeâcomponent seismometer operating since 23 May 2002 to 30 January 2003, including
the first 34 days of the crisis. Before the crisis, we recognize three bellâshaped classes of
spectra with maxima falling in the range 1â5 Hz. Spectral content has two main changes, the
most prominent one occurring at the crisis onset when the frequency peak at âŒ0.3 Hz
increases in amplitude. Independent component analysis extracts three timeâstable
independent oscillations that peaked at 1.1, 1.8, and 2.5 Hz, with radial and shallow
polarization indicating a stable source mechanism. Energy of the explosions is lognormally
distributed, except during a 2 month time interval before the crisis when it also shows a
higher mean value. The interoccurrence time distributions display an homogeneous
Poissonian behavior with a mean intertime of 250 s, without changes at the crisis onset. Only
swarms of explosions are not ruled by a Poisson process and display higher occurrence rates
and higher energies. Finally, we depict a scheme of the crisis. A modification of the
equilibrium is induced by rising magma that produces a change in the boundary conditions of
the plumbing system. The escape from the equilibrium produces, at first, variations in the
usual statistics of the explosions, then it leads to the lava effusion and to a pressure drop in
the plumbing system that induces a deep gas slug nucleation and the excitation of low
frequencies
A statistical study of the Stromboli volcano explosion-quakes before and during 2002-2003 eruptive crisis
We study the seismic wavefield and the statistical properties
of the Stromboli volcano explosions preceding and during 2002-2003 crisis.
We analyze the recordings of a three-component seismometer operating since
23/05/2002 to 30/01/2003, including the first 34 days of the crisis. Before
the crisis, we recognize three bell-shaped classes of spectra with maxima falling
in the range 1â5 Hz. Spectral content has two main changes, the most prominent
one occurring at the crisis onset when the frequency peak at âŒ0:3 Hz
increases in amplitude. Independent Component Analysis extracts three timestable
independent oscillations peaked at 1.1, 1.8, and 2.5 Hz, respectively,
with radial and shallow polarization indicating a stable source mechanism.
Energy of the explosions is log-normally distributed, except during a twomonth
time interval before the crisis when it shows also a higher mean value.
The inter-occurrence time distributions display an homogeneous poissonian
behaviour with a mean inter-time of 250 s, without changes at the crisis onset.
Only swarms of explosions are not ruled by a Poisson process and display
higher occurrence rates and higher energies. Finally, we depict a scheme
of the crisis. A modification of the equilibrium is induced by rising magma
that produces a change in the boundary conditions of the plumbing system.
The escape from the equilibrium produces, at first, variations in the usual
statistics of the explosions, then it leads to the lava effusion and to a pressure
drop in the plumbing systems that induces a deep gas slug nucleation
and the excitation of low frequencies
Microbioreactor (micro-Matrix) potential in aerobic and anaerobic conditions with different industrially relevant microbial strains
Microscale fermentation systems are important high throughput tools in clone selection, and bioprocess set up and optimization, since they provide several parallel experiments in controlled conditions of pH, temperature, agitation, and gas flow rate. In this work we evaluated the performance of biotechnologically relevant strains with different respiratory requirements in the micro-Matrix microbioreactor. In particular Escherichia coli K4 requires well aerated fermentation conditions to improve its native production of chondroitin-like capsular polysaccharide, a biomedically attractive polymer. Results from batch and fed-batch experiments demonstrated high reproducibility with those obtained on 2 L reactors, although highlighting a pronounced volume loss for longer-term experiments. Basfia succiniciproducens and Actinobacillus succinogenes need CO2 addition for the production of succinic acid, a building block with several industrial applications. Different CO2 supply modes were tested for the two strains in 24 h batch experiments and results well compared with those obtained on lab-scale bioreactors. Overall, it was demonstrated that the micro-Matrix is a useful scale-down tool that is suitable for growing metabolically different strains in simple batch process, however, a series of issues should still be addressed in order to fully exploit its potential
PyRTlib: an educational Python-based library for non-scattering atmospheric microwave radiative transfer computations
This article introduces PyRTlib, a new standalone Python package for non-scattering line-by-line microwave radiative transfer simulations. PyRTlib is a flexible and user-friendly tool for computing down- and upwelling brightness temperatures and related quantities (e.g., atmospheric absorption, optical depth, opacity, mean radiating temperature) written in Python, a language commonly used nowadays for scientific software development, especially by students and early-career scientists. PyRTlib allows for simulating observations from ground-based, airborne, and satellite microwave sensors in clear-sky and in cloudy conditions (under non-scattering Rayleigh approximation). The intention for PyRTlib is not to be a competitor to state-of-the-art atmospheric radiative transfer codes that excel in speed and/or versatility (e.g., ARTS, Atmospheric Radiative Transfer Simulator; RTTOV, Radiative Transfer for TOVS (Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder)). The intention is to provide an educational tool, completely written in Python, to readily simulate atmospheric microwave radiative transfer from a variety of input profiles, including predefined climatologies, global radiosonde archives, and model reanalysis. The paper presents quick examples for the built-in modules to access popular open data archives. The paper also presents examples for computing the simulated brightness temperature for different platforms (ground-based, airborne, and satellite), using various input profiles, showing how to easily modify other relevant parameters, such as the observing angle (zenith, nadir, slant), surface emissivity, and gas absorption model. PyRTlib can be easily embedded in other Python codes needing atmospheric microwave radiative transfer (e.g., surface emissivity models and retrievals). Despite its simplicity, PyRTlib can be readily used to produce present-day scientific results, as demonstrated by two examples showing (i) an absorption model comparison and validation with ground-based radiometric observations and (ii) uncertainty propagation of spectroscopic parameters through the radiative transfer calculations following a rigorous approach. To our knowledge, the uncertainty estimate is not provided by any other currently available microwave radiative transfer code, making PyRTlib unique for this aspect in the atmospheric microwave radiative transfer code scenario.</p
Interpretation of observed microwave signatures from ground dual polarization radar and space multi-frequency radiometer for the 2011 GrĂmsvötn volcanic eruption
Abstract. The important role played by ground-based microwave weather radars for the monitoring of volcanic ash clouds has been recently demonstrated. The potential of microwaves from satellite passive and ground-based active sensors to estimate near-source volcanic ash cloud parameters has been also proposed, though with little investigation of their synergy and the role of the radar polarimetry. The goal of this work is to show the potentiality and drawbacks of the X-band dual polarization (DPX) radar measurements through the data acquired during the latest GrĂmsvötn volcanic eruptions that took place in May 2011 in Iceland. The analysis is enriched by the comparison between DPX data and the observations from the satellite Special Sensor Microwave Imager/Sounder (SSMIS) and a C-band single polarization (SPC) radar. SPC, DPX, and SSMIS instruments cover a large range of the microwave spectrum, operating respectively at 5.4, 3.2, and 0.16â1.6âŻcm wavelengths
3DVAR assimilation of SSM/I data over the sea for the IOP2b MAP case
International audienceData assimilation by 3DVAR of data from the Special Sensor Microwave/Imager (SSM/I) has been performed to study the IOP2b case (19-21 September 1999) of the Mesoscale Alpine Programme (MAP). Only data over the sea surface are used to avoid the contamination of the surface emissivity. Moreover, the rainy data are filtered out because the assimilation algorithm of 3DVAR does not take into account the scattering processes. SSM/I data are assimilated in two different ways: as Brightness Temperature directly, or as Precipitable Water and surface wind speed retrieved from the Brightness Temperature. The effect of the thinning of the observations has been studied and a set of sensitivity test cases has been carried out; the one by one removal of the SSM/I frequencies from the initial dataset allows to evaluate their impact on the Initial Conditions. A few experiments are performed using these new Initial Conditions to initialize the MM5 (PSU/NCAR) model. The results show that the assimilation of the retrieved quantities, i.e. Precipitable Water and surface wind speed, does not produces large improvement in the Initial Conditions. Vice versa, the assimilation of the Brightness temperatures produces a large variability of the Initial Conditions. The forecast experiments show that the model is very sensitive to the 22GHz and 37GHz frequencies
Metabolomic Analysis Reveals Increased Aerobic Glycolysis and Amino Acid Deficit in a Cellular Model of Amyotrophic Lateral Sclerosis
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