Biology subjects

Nielsen, E.

Publications and source records attributed to Nielsen, E..

5 recordsLinked to original sources

bioRxiv2025

Autophagic degradation of EIN3 ensures developmental plasticity and recovery from environmental stress in Arabidopsis

Ethylene signaling, mediated by the key transcription factor EIN3, regulates diverse developmental processes and stress adaptations, including hypocotyl growth, aging, and submergence tolerance. Autophagy, a cellular recycling process, also facilitates adaptation by reprogramming cellular components. While EIN3 degradation via the proteasome is well established, its connection to autophagy remains unclear. Here, we show that EIN3 turnover is directly regulated by ATG8-mediated autophagy. Consistently, autophagy-deficient plants exhibit impaired EIN3-dependent hypocotyl growth during light-to-dark transitions. Additionally, EIN3 accumulation contributes to the premature senescence observed in atg mutants. Beyond development, our combination of cell imaging, phenotypic analyses, and proteomics reveals that autophagy is essential for EIN3-driven transcriptional reprogramming during submergence. Together, our findings uncover a direct role for autophagy in regulating EIN3 stability, providing mechanistic insight into how this process fine-tunes ethylene responses in growth and stress adaptation.

plant biology↗

bioRxiv2023

Dopamine alters the effect of brain stimulation on decision-making

Non-invasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS), show promise in treating cognitive and behavioural impairments in clinical conditions. However, optimisation of such clinical applications requires a better understanding of how tDCS alters cognition and behaviour. Existing evidence implicates dopamine in the way tDCS alters brain activity and plasticity, however, there is as yet no causal evidence for a role of dopamine in tDCS effects on cognition and behaviour. Here, in a preregistered, double-blinded study, we examined how pharmacologically manipulating dopamine altered the effect of tDCS on the speed-accuracy trade-off, which taps ubiquitous strategic cognitive processes. Cathodal tDCS was delivered over the left prefrontal cortex and the superior medial frontal cortex before participants completed a dot-motion task, deciding the direction of moving dots under instructions to emphasize speed, accuracy, or both. We leveraged computational modelling to uncover how our manipulations altered latent decisional processes driving the speed-accuracy tradeoff. We show that dopamine in combination with tDCS (but not tDCS alone, nor dopamine alone) not only impaired decision accuracy, but also impaired discriminability, which suggests that these manipulations altered the encoding or representation of discriminative evidence. This is, to the best of our knowledge, the first direct evidence implicating dopamine in the way tDCS affects cognition and behaviour. Significance statementTranscranial direct current stimulation (tDCS) can improve cognitive and behavioural impairments in clinical conditions, however better understanding of its mechanisms is required to optimise future clinical applications. Here, using a pharmacological approach to manipulate brain dopamine levels in healthy adults, we demonstrate a role for dopamine in the effects of tDCS in the speed-accuracy trade-off, a strategic cognitive process ubiquitous in many contexts. In doing so, we provide direct evidence implicating dopamine in the way tDCS affects cognition and behaviour.

neuroscience↗

bioRxiv2023

Functional Relations of CSLD2, CSLD3, and CSLD5 Proteins during Cell Wall Synthesis in Arabidopsis

Plant cell expansion is a dynamic process that is physically constrained by the deposition of new cell wall components. During tip growth, new cell wall materials are delivered at a restricted plasma membrane domain which results in a highly polarized expansion within that specified domain. Previous studies demonstrated that this process requires the activities of members of the Cellulose Synthase-Like D (CSLD) subfamily of cell wall synthases. CSLD3 displays {beta}-1,4 glucan synthase activity, but whether other members of CSLD subfamily share this conserved biochemical activity, and whether CSLD proteins form higher-order complexes to perform {beta}-1,4 glucan synthase activities have not been determined. Here, we use genetic methods to demonstrate that CSLD2 and CSLD3 functions are interchangeable during root hair elongation and cell plate formation, while CSLD5 provides a unique and irreplaceable function in the formation of cell plates. Importantly, genetic analysis with inactivated versions of CSLD3 show that, unlike CESA proteins, CSLDs do not require the simultaneous presence of different isoforms to perform catalytic cell wall synthase activities. In vitro biochemical activity experiments confirmed that CSLD2, CSLD3, and CSLD5 proteins displayed {beta}-1,4 glucan synthases activities. Taken together, these results indicated that while all three vegetatively expressed CSLD proteins possess conserved {beta}-1,4 glucan synthase activities, that CSLD5 has a more complicated and specialized role during cell plate formation.

cell biology↗

bioRxiv2020

Genome-wide analysis clarifies the population genetic structure of wild Gilthead Sea Bream (Sparus aurata)

Gilthead sea bream is an important target for both recreational and commercial fishing in Europe, where it is also one of the most important cultured fish. Its distribution range goes from the Mediterranean to the African and European coasts of the North-East Atlantic. So far, the genetic structure of this species in the wild has been studied with microsatellite DNA, but the pattern of differentiation could not be fully clarified. In this study, almost 1000 wild sea bream from 23 locations in the Mediterranean Sea and Atlantic ocean where genotyped at 1159 SNP markers, of which 18 potentially under selection. Neutral markers suggested the presence of a weak subdivision into three genetic clusters: Atlantic, West and East Mediterranean. This last group could be further subdivided into an Ionian/Adriatic and an Aegean group using outlier markers. Seascape analysis suggested that this differentiation was mainly due to difference in salinity, and this was also supported by preliminary genomic functional analysis. These results are of fundamental importance for the development of proper management of this species in the wild and are a first step toward the study of the potential genetic impact of the sea bream aquaculture industry.View Full Text

ecology↗

bioRxiv2020

Functional Characterization of fer-ts, a ts- FERONIA Mutant Allele That Alters Root Hair Growth

In plants, root hairs undergo a highly-polarized form of cell expansion called tip-growth, in which cell wall deposition is restricted to the root hair apex. In order to identify essential cellular components that might have been missed in earlier genetic screens we identified conditional temperature sensitive (ts) root hair mutants by EMS mutagenesis. Here we describe one of these mutants, fer-ts (feronia-temperature sensitive). Mutant fer-ts seedlings grew normally at normal temperatures (20{degrees}C), but failed to form root hairs at elevated temperatures (30{degrees}C). Map based-cloning and whole genome sequencing revealed that fer-ts resulted from a G41S substitution in the extracellular domain of FERONIA (FER). A functional fluorescent fusion of FER containing the fer-ts mutation localized to plasma membranes, but was subject to enhanced protein turnover at elevated temperatures. While tip-growth was rapidly inhibited by addition of RALF1 peptides in both wild-type and fer-ts mutants at normal temperatures, root elongation of fer-ts seedlings was resistant to added RALF1 peptide at elevated temperatures. Additionally, at elevated temperatures fer-ts seedlings displayed altered ROS accumulation upon auxin treatment and phenocopied constitutive fer mutant responses to a variety of plant hormone treatments. Molecular modeling and sequence comparison with other CrRLK1L receptor family members revealed that the mutated glycine in fer-ts is highly conserved, but is not located in the recently characterized RALF23 and LORELI-LIKE-GLYCOPROTEIN (LLG2) binding domains, perhaps suggesting that fer-ts phenotypes may not be directly due to loss of binding to RALF1 peptides.

plant biology↗