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991.
Charitha Galva Viktor Kirik Jelmer J. Lindeboom Despoina Kaloriti David M. Rancour Patrick J. Hussey Sebastian Y. Bednarek David W. Ehrhardt John C. Sedbrook 《The Plant cell》2014,26(11):4409-4425
The microtubule plus-end tracking proteins (+TIPs) END BINDING1b (EB1b) and SPIRAL1 (SPR1) are required for normal cell expansion and organ growth. EB proteins are viewed as central regulators of +TIPs and cell polarity in animals; SPR1 homologs are specific to plants. To explore if EB1b and SPR1 fundamentally function together, we combined genetic, biochemical, and cell imaging approaches in Arabidopsis thaliana. We found that eb1b-2 spr1-6 double mutant roots exhibit substantially more severe polar expansion defects than either single mutant, undergoing right-looping growth and severe axial twisting instead of waving on tilted hard-agar surfaces. Protein interaction assays revealed that EB1b and SPR1 bind each other and tubulin heterodimers, which is suggestive of a microtubule loading mechanism. EB1b and SPR1 show antagonistic association with microtubules in vitro. Surprisingly, our combined analyses revealed that SPR1 can load onto microtubules and function independently of EB1 proteins, setting SPR1 apart from most studied +TIPs in animals and fungi. Moreover, we found that the severity of defects in microtubule dynamics in spr1 eb1b mutant hypocotyl cells correlated well with the severity of growth defects. These data indicate that SPR1 and EB1b have complex interactions as they load onto microtubule plus ends and direct polar cell expansion and organ growth in response to directional cues. 相似文献
992.
Abdellah Barakate James D. Higgins Sebastian Vivera Jennifer Stephens Ruth M. Perry Luke Ramsay Isabelle Colas Helena Oakey Robbie Waugh F. Chris H. Franklin Susan J. Armstrong Claire Halpin 《The Plant cell》2014,26(2):729-740
In many cereal crops, meiotic crossovers predominantly occur toward the ends of
chromosomes and 30 to 50% of genes rarely recombine. This limits the exploitation of
genetic variation by plant breeding. Previous reports demonstrate that chiasma
frequency can be manipulated in plants by depletion of the synaptonemal complex
protein ZIPPER1 (ZYP1) but conflict as to the direction of change, with fewer
chiasmata reported in Arabidopsis thaliana and more crossovers
reported for rice (Oryza sativa). Here, we use RNA interference
(RNAi) to reduce the amount of ZYP1 in
barley (Hordeum vulgare) to only 2 to 17% of normal zygotene levels.
In the ZYP1RNAi lines, fewer than half of the chromosome
pairs formed bivalents at metaphase and many univalents were observed, leading to
chromosome nondisjunction and semisterility. The number of chiasmata per cell was
reduced from 14 in control plants to three to four in the ZYP1-depleted lines,
although the localization of residual chiasmata was not affected. DNA double-strand
break formation appeared normal, but the recombination pathway was defective at later
stages. A meiotic time course revealed a 12-h delay in prophase I progression to the
first labeled tetrads. Barley ZYP1 appears to function similarly to ZIP1/ZYP1 in
yeast and Arabidopsis, with an opposite effect on crossover number
to ZEP1 in rice, another member of the Poaceae. 相似文献
993.
994.
AMP‐activated protein kinase is involved in induction of protective autophagy in astrocytes exposed to oxygen‐glucose deprivation
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995.
996.
Sarah Refai Kati Wassmann Sebastian van Helmont Stefanie Berger Uwe Deppenmeier 《Journal of industrial microbiology & biotechnology》2014,41(12):1763-1772
Very recently, it was shown that the addition of acetate or ethanol led to enhanced biogas formation rates during an observation period of 24 h. To determine if increased methane production rates due to ethanol addition can be maintained over longer time periods, continuous reactors filled with biogas sludge were developed which were fed with the same substrates as the full-scale reactor from which the sludge was derived. These reactors are well reflected conditions of a full-scale biogas plant during a period of 14 days. When the fermenters were pulsed with 50–100 mM ethanol, biomethanation increased by 50–150 %, depending on the composition of the biogas sludge. It was also possible to increase methane formation significantly when 10–20 mM pure ethanol or ethanolic solutions (e.g. beer) were added daily. In summary, the experiments revealed that “normal” methane production continued to take place, but ethanol led to production of additional methane. 相似文献
997.
998.
Nilanjan Pal Chowdhury Amr M. Mowafy Julius K. Demmer Vikrant Upadhyay Sebastian Koelzer Elamparithi Jayamani Joerg Kahnt Marco Hornung Ulrike Demmer Ulrich Ermler Wolfgang Buckel 《The Journal of biological chemistry》2014,289(8):5145-5157
Electron bifurcation is a fundamental strategy of energy coupling originally discovered in the Q-cycle of many organisms. Recently a flavin-based electron bifurcation has been detected in anaerobes, first in clostridia and later in acetogens and methanogens. It enables anaerobic bacteria and archaea to reduce the low-potential [4Fe-4S] clusters of ferredoxin, which increases the efficiency of the substrate level and electron transport phosphorylations. Here we characterize the bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans, which couple the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. EtfAf contains one FAD (α-FAD) in subunit α and a second FAD (β-FAD) in subunit β. The distance between the two isoalloxazine rings is 18 Å. The EtfAf-NAD+ complex structure revealed β-FAD as acceptor of the hydride of NADH. The formed β-FADH− is considered as the bifurcating electron donor. As a result of a domain movement, α-FAD is able to approach β-FADH− by about 4 Å and to take up one electron yielding a stable anionic semiquinone, α-FAD⨪, which donates this electron further to Dh-FAD of BcdAf after a second domain movement. The remaining non-stabilized neutral semiquinone, β-FADH•, immediately reduces ferredoxin. Repetition of this process affords a second reduced ferredoxin and Dh-FADH− that converts crotonyl-CoA to butyryl-CoA. 相似文献
999.
Levente Jozsef Keitaro Tashiro Andrew Kuo Eon Joo Park Athanasia Skoura Sebastian Albinsson Felix Rivera-Molina Kenneth D. Harrison Yasuko Iwakiri Derek Toomre William C. Sessa 《The Journal of biological chemistry》2014,289(13):9380-9395
Despite recent advances in understanding store-operated calcium entry (SOCE) regulation, the fundamental question of how ER morphology affects this process remains unanswered. Here we show that the loss of RTN4, is sufficient to alter ER morphology and severely compromise SOCE. Mechanistically, we show this to be the result of defective STIM1-Orai1 coupling because of loss of ER tubulation and redistribution of STIM1 to ER sheets. As a functional consequence, RTN4-depleted cells fail to sustain elevated cytoplasmic Ca2+ levels via SOCE and therefor are less susceptible to Ca2+ overload induced apoptosis. Thus, for the first time, our results show a direct correlation between ER morphology and SOCE and highlight the importance of RTN4 in cellular Ca2+ homeostasis. 相似文献
1000.
The present study investigated the validity of a simplified muscle volume assessment that uses only the maximum anatomical cross-sectional area (ACSAmax), the muscle length (LM) and a muscle-specific shape factor for muscle volume calculation ( Albracht et al., 2008, J Biomech 41, 2211–2218). The validation on the example of the triceps surae (TS) muscles was conducted in two steps. First LM, ACSAmax, muscle volume and shape factor were calculated from magnet resonance image muscle reconstructions of the soleus (SO), gastrocnemius medialis (GM) and lateralis (GL) of a group of untrained individuals (n=13), endurance (n=9) and strength trained (n=10) athletes. Though there were significant differences in the muscle dimensions, the shape factors were similar across groups and were in average 0.497±0.026, 0.596±0.030, and 0.556±0.041 for the SO, GM and GL respectively. In a second step, the shape factors were applied to an independent recreationally active group (n=21) to compare the muscle volume assessed by the simplified method to the results from whole muscle reconstructions. There were no significant differences between the volumes assessed by the two methods. In conclusion, assessing TS muscle volume on the basis of the reported shape factors is valid across populations and the root mean square differences to whole muscle reconstruction of 7.9%, 4.8% and 8.3% for SO, GM and GL show that the simplified method is sensitive enough to detect changes in muscle volume in the context of degeneration, atrophy or hypertrophy. 相似文献