191 research outputs found
Unraveling the mechanism of TTL genes in cellulose biosynthesis
As sessile organisms, plants require mechanisms to sense and respond to the challenging environment, that encompass both biotic and abiotic factors that results in differential development. In these conditions is essential to balance growth and stress responses. As cell walls shape plant growth, this differential growth response cause alterations to the plant cell wall where cellulose is the major component. Therefore, understanding the mechanisms that regulate cellulose biosynthesis is essential to develop strategies to improve plant production. In Arabidopsis, the TETRATRICOPEPTIDE THIOREDOXIN-LIKE (TTL) gene family is composed by four members (TTL1 to TTL4) and mutations in TTL1, TTL3, and TTL4 genes cause reduced growth under salt and osmotic stress due to defects in plant cell wall integrity. We observe association of TTL3 with most core components in traducing BR signalling, such as LRR-RLK BRI1 or GSK3 BIN2 that modulate cellulose biosynthesis through phosphorylating cellulose synthases. Here, we show that ttl mutants present defects in the plant cell wall, particularly in Isoxaben, salt or sucrose stress. Spinning disk microscopy in etiolated hypocotyls reveals that, TTL proteins are responsible for the cellulose synthase complex (CSC) stability in plasma membrane (PM) upon sucrose stress. Moreover, TTL3 associates with LRR-RLKs that have been shown to be important for cellulose biosynthesis such as FEI1 in the FEI1/FEI2/SOS5 pathway. We aim to investigate the mechanisms by which TTL proteins regulate CesA stability in PM under stress, using a combination of genetics, biochemical, and molecular and cell biology approaches.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech.
This work was supported by grants from: (1) Ministerio de Ciencia e InnovaciĂłn BIO2014-55380-R, BIO2014-56153-REDT; (2) Ministerio de EconomĂa, Industria y Competitividad (BES-2015-071256
Peripheral membrane TTL proteins safeguard cellulose synthesis under stress.
Land plants provide around eighty percent of biomass on Earth and roughly one-third corresponds to cellulose (Bar-On et al 2018). Despite its biological and societal importance, many aspects of cellulose biosynthesis and regulation remain elusive. Controlled primary cell wall remodeling allows plant growth under stressful conditions, but how these changes are conveyed to adjust cellulose synthesis is not well understood (Colin et al 2023).
In this work, we identify that Tetratricopeptide Thioredoxin-Like (TTL) proteins, which we previous describe as a scaffold of brassinosteroids signalling components, are also new members of the cellulose synthase complex (CSC) and we describe their unique and hitherto unknown dynamic association with the CSC under cellulose-deficient conditions (Amorim-Silva et al 2019 and Kesten, GarciÌa-Moreno, Amorim-Silva et al 2022). We found out that TTLs are essential for maintaining cellulose synthesis under high salinity conditions, establishing a stress-resilient cortical microtubule array, and stabilizing CSCs at the plasma membrane. To fulfill these functions, TTLs interact with Cellulose Synthase1 (CESA1) and engage with cortical microtubules to promote their polymerization. We propose that TTLs function as bridges connecting stress perception with dynamic regulation of cellulose biosynthesis at the plasma membrane. In addition, we are currently working to identify and characterize new components involved in TTLs function and dynamics during cellulose biosynthesis under saline stress conditions.
References:
Amorim-Silva et al. 2019 The Plant Cell
Bar-On et al. 2018 Proc. Natl. Acad. Sci.
Colin et al. 2023 The Plant Cell
Kesten, GarciÌa-Moreno, Amorim-Silva et al. 2022 Sci. Adv.Meeting attendance was supported by Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech.
This work was funded by the Spanish Ministry for Science and Innovation (MCIN/AEI/ 10.13039/501100011033) (PGC2018-098789-B-I00) and (PID2019-107657RB-C22) to MAB, NRL and AC respectively. The Andalusian Research Plan co-financed by the European Union (PAIDI 2020-PY20_00084) to MAB andde AndalucĂa UMA-FEDER project (grant UMA18-FEDERJA-154) to NRL, and the Swiss National foundation to CSR (SNF 31003A_163065/1 to AM). CK was supported by a Peter und Traudl Engelhorn-Stiftung fellowship, an ETH Career Seed Grant (SEED-05 19-2) of the ETH Foundation, an Emerging Investigator grant (NNF20OC0060564) of the Novo Nordisk Foundation, and an Experiment grant (R346-2020-1546) of the Lundbeck foundation. AGM and FP were supported by BES-2015-071256 and FPU19/02219 fellowships respectively. VAS was supported by an Emerging Investigator research project (UMA20-FEDERJA-007) and co-financed by the âPrograma Operativo FEDER 2014-2020â and by the âConsejerĂa de EconomĂa y Conocimiento de la Junta de AndalucĂaâ.
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
Temperature dependence of plankton community metabolism in the subtropical and tropical oceans
Here we assess the temperature dependence of the metabolic rates (gross primary production
(GPP), community respiration (CR), and the ratio GPP/CR) of oceanic plankton communities. We compile
data from 133 stations of the Malaspina 2010 Expedition, distributed among the subtropical and tropical
Atlantic, Pacific, and Indian oceans. We used the in vitro technique to measured metabolic rates during 24 h
incubations at three different sampled depths: surface, 20%, and 1% of the photosynthetically active
radiation measured at surface. We also measured the % of ultraviolet B radiation (UVB) penetrating at surface
waters. GPP and CR rates increased with warming, albeit different responses were observed for each sampled
depth. The overall GPP/CR ratio declined with warming. Higher activation energies (Ea) were derived for
both processes (GPPChla = 0.97; CRChla = 1.26; CRHPA = 0.95 eV) compared to those previously reported. The
Indian Ocean showed the highest Ea (GPPChla = 1.70; CRChla = 1.48; CRHPA = 0.57 eV), while the Atlantic
Ocean showed the lowest (GPPChla = 0.86; CRChla = 0.77; CRHPA = 0.13 eV). We believe that the difference
between previous assessments and the ones presented here can be explained by the overrepresentation of
Atlantic communities in the previous data sets. We found that UVB radiation also affects the temperature
dependence of surface GPP, which decreased rather than increased under high levels of UVB. Ocean
warming, which causes stratification and oligotrophication of the subtropical and tropical oceans, may lead
to reduced surface GPP as a result of increased penetration of UVB radiation.En prens
Genes Expressed in Specific Areas of the Human Fetal Cerebral Cortex Display Distinct Patterns of Evolution
The developmental mechanisms through which the cerebral cortex increased in size and complexity during primate evolution are essentially unknown. To uncover genetic networks active in the developing cerebral cortex, we combined three-dimensional reconstruction of human fetal brains at midgestation and whole genome expression profiling. This novel approach enabled transcriptional characterization of neurons from accurately defined cortical regions containing presumptive Broca and Wernicke language areas, as well as surrounding associative areas. We identified hundreds of genes displaying differential expression between the two regions, but no significant difference in gene expression between left and right hemispheres. Validation by qRTPCR and in situ hybridization confirmed the robustness of our approach and revealed novel patterns of area- and layer-specific expression throughout the developing cortex. Genes differentially expressed between cortical areas were significantly associated with fast-evolving non-coding sequences harboring human-specific substitutions that could lead to divergence in their repertoires of transcription factor binding sites. Strikingly, while some of these sequences were accelerated in the human lineage only, many others were accelerated in chimpanzee and/or mouse lineages, indicating that genes important for cortical development may be particularly prone to changes in transcriptional regulation across mammals. Genes differentially expressed between cortical regions were also enriched for transcriptional targets of FoxP2, a key gene for the acquisition of language abilities in humans. Our findings point to a subset of genes with a unique combination of cortical areal expression and evolutionary patterns, suggesting that they play important roles in the transcriptional network underlying human-specific neural traits
Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects
The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E be able to explain the observations
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