- F. Breman (1)
- Phillip Chlap (1)
- Matias D. Zurbriggen (1)
- Alexander Dovzhenko (1)
- Christian Fleck (1)
- Hartmann Harz (1)
- Ken Ichiro Hayashi (1)
- G. Jager (1)
- M. Luijten (1)
- Alistair M. Middleton (1)
- V. Merckx (1)
- Klaus Palme (1)
- N.F. Ramsey (1)
- Fugang Ren (1)
- Olaf Ronneberger (1)
- Rainer Uhl (1)
- Wilfried Weber (1)
- Sabrina Wend (1)
Data-Driven Modeling of Intracellular Auxin Fluxes Indicates a Dominant Role of the ER in Controlling Nuclear Auxin Uptake
Middleton, Alistair M. ; Bosco, Cristina Dal; Chlap, Phillip ; Bensch, Robert ; Harz, Hartmann ; Ren, Fugang ; Bergmann, Stefan ; Wend, Sabrina ; Weber, Wilfried ; Hayashi, Ken Ichiro ; Zurbriggen, Matias D. ; Uhl, Rainer ; Ronneberger, Olaf ; Palme, Klaus ; Fleck, Christian ; Dovzhenko, Alexander - \ 2018
Cell Reports 22 (2018)11. - ISSN 2211-1247 - p. 3044 - 3057.
auxin - auxin flux - auxin sensor - endoplasmic reticulum - fluorescent aux - mathematical modeling - microscopy - nucleus - protoplasts - single cells
In plants, the phytohormone auxin acts as a master regulator of developmental processes and environmental responses. The best characterized process in the auxin regulatory network occurs at the subcellular scale, wherein auxin mediates signal transduction into transcriptional programs by triggering the degradation of Aux/IAA transcriptional repressor proteins in the nucleus. However, whether and how auxin movement between the nucleus and the surrounding compartments is regulated remain elusive. Using a fluorescent auxin analog, we show that its diffusion into the nucleus is restricted. By combining mathematical modeling with time course assays on auxin-mediated nuclear signaling and quantitative phenotyping in single plant cell systems, we show that ER-to-nucleus auxin flux represents a major subcellular pathway to directly control nuclear auxin levels. Our findings propose that the homeostatically regulated auxin pool in the ER and ER-to-nucleus auxin fluxes underpin auxin-mediated downstream responses in plant cells. Middleton et al. study how the plant phytohormone auxin enters the nucleus by using quantitative phenotyping in single plant cell systems and bespoke mathematical models that relate controlled perturbations to experimentally measurable responses. Their findings show that auxin predominantly enters the nucleus via the endoplasmic reticulum.
Tentative Evidence for Striatal Hyperactivity in Adolescent Cannabis-Using Boys: A Cross-Sectional Multicenter fMRI Study
Jager, G. ; Block, R.I. ; Luijten, M. ; Ramsey, N.F. - \ 2013
Journal of Psychoactive Drugs 45 (2013)2. - ISSN 0279-1072 - p. 156 - 167.
brain-development - reward circuitry - activation - responsivity - anticipation - behavior - nucleus
Adolescents' risk-taking behavior has been linked to a maturational imbalance between reward (“go”) and inhibitory-control (“stop”)-related brain circuitry. This may drive adolescent drug-taking, such as cannabis use. In this study, we assessed the non-acute effects of adolescent cannabis use on reward-related brain function. We performed a two-site (United States and Netherlands; pooled data) functional magnetic resonance imaging (fMRI) study with a cross-sectional design. Twenty-one abstinent but frequent cannabis-using boys were compared with 24 non-using peers on reward-related brain function, using a monetary incentive delay task with fMRI. Focus was on anticipatory and response stages of reward and brain areas critically involved in reward processing like the striatum. Performance in users was normal. Region-of-interest analysis indicated striatal hyperactivity during anticipatory stages of reward in users. Intriguingly, this effect was most pronounced during non-rewarding events. Striatal hyperactivity in adolescent cannabis users may signify an overly sensitive motivational brain circuitry. Frequent cannabis use during adolescence may induce diminished ability to disengage the motivational circuit when no reward can be obtained. This could strengthen the search for reinforcements like drugs of abuse, even when facing the negative (non-rewarding) consequences.
DNA sequence evolution in fast evolving mitochondrial DNA nad1 exons in Geraniaceae and Plantaginaceae
Bakker, F.T. ; Breman, F. ; Merckx, V. - \ 2006
Taxon 55 (2006)4. - ISSN 0040-0262 - p. 887 - 896.
land plants - flowering plants - chloroplast dna - substitution rates - polymerase-gamma - gene content - codon usage - rna - phylogeny - nucleus
Previously, nucleotide substitution rates in mitochondrial DNA of Geraniaceae and Plantaginaceae have been shown to be exceptionally high compared with other angiosperm mtDNA lineages. It has also been shown that mtDNA introns were lost in Geraniaceae and Plantaginaceae. In this study we compile 127 DNA sequences from two partial exons of the mtDNA nad1 gene in Geraniaceae, Plantaginaceae, and other angiosperm groups for which rate accelerations have not been reported, to assess the extent and nature of the nucleotide substitution rate acceleration. Whereas Litorella appears to have undergone a rate acceleration comparable to that observed in Plantago, the Geraniacean sister group representative Hypseocharis biloba has not, indicating that the rate change has occurred between the split of Hypseocharis and the rest of the Geraniaceae. Silent/non-silent rate ratios ¿ have decreased threefold in the "fast mtDNA" clades compared with other angiosperms, whereas their codon usage bias is around 20% lower. Absence of RNA editing in Geraniacean and Plantago mtDNA genes is confirmed. Possible causes for the exceptional substitution rate accelerations observed in these lineages are discussed in terms of the retroprocessing process or the possibility of affected mitochondrial DNA polymerase ¿ proofreading accuracy control