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161.
162.
Slootweg E Roosien J Spiridon LN Petrescu AJ Tameling W Joosten M Pomp R van Schaik C Dees R Borst JW Smant G Schots A Bakker J Goverse A 《The Plant cell》2010,22(12):4195-4215
The Rx1 protein, as many resistance proteins of the nucleotide binding-leucine-rich repeat (NB-LRR) class, is predicted to be cytoplasmic because it lacks discernable nuclear targeting signals. Here, we demonstrate that Rx1, which confers extreme resistance to Potato virus X, is located both in the nucleus and cytoplasm. Manipulating the nucleocytoplasmic distribution of Rx1 or its elicitor revealed that Rx1 is activated in the cytoplasm and cannot be activated in the nucleus. The coiled coil (CC) domain was found to be required for accumulation of Rx1 in the nucleus, whereas the LRR domain promoted the localization in the cytoplasm. Analyses of structural subdomains of the CC domain revealed no autonomous signals responsible for active nuclear import. Fluorescence recovery after photobleaching and nuclear fractionation indicated that the CC domain binds transiently to large complexes in the nucleus. Disruption of the Rx1 resistance function and protein conformation by mutating the ATP binding phosphate binding loop in the NB domain, or by silencing the cochaperone SGT1, impaired the accumulation of Rx1 protein in the nucleus, while Rx1 versions lacking the LRR domain were not affected in this respect. Our results support a model in which interdomain interactions and folding states determine the nucleocytoplasmic distribution of Rx1. 相似文献
163.
Habitat fragmentation can affect levels of herbivory in plant populations if plants and herbivores are differentially affected
by fragmentation. Moreover, if herbivores are top–down controlled by predators or parasitoids, herbivory may also be affected
by differential effects of fragmentation on herbivores and their natural enemies. We used natural Silene latifolia populations to examine the effects of plant population size and isolation on the level of herbivory by the seed predating
noctuid Hadena bicruris and the rate of parasitism of the herbivore by its parasitoids. In addition, we examined oviposition rate, herbivory and
parasitism in differently sized experimental populations. In natural populations, the level of herbivory increased and the
rate of parasitism decreased with decreasing plant population size and increasing degree of isolation. The number of parasitoid
species also declined with decreasing plant population size. In the experimental populations, the level of herbivory was also
higher in smaller populations, in accordance with higher oviposition rates, but was not accompanied by lower rates of parasitism.
Similarly, oviposition rate and herbivory, but not parasitism rate, increased near the edges of populations. These results
suggests that in this system with the well dispersing herbivore H. bicruris, habitat fragmentation increases herbivory of the plant through a behavioural response of the moth that leads to higher oviposition
rates in fragmented populations with a reduced population size, increased isolation and higher edge-to-interior ratio. Although
the rate of parasitism and the number of parasitoid species declined with decreasing population size in the natural populations,
we argue that in this system it is unlikely that this decline made a major contribution to increased herbivory. 相似文献
164.
Nanne M. Kamerbeek Arjen J. J. Olsthoorn Marco W. Fraaije Dick B. Janssen 《Applied microbiology》2003,69(1):419-426
The 4-hydroxyacetophenone monooxygenase (HAPMO) from Pseudomonas fluorescens ACB catalyzes NADPH- and oxygen-dependent Baeyer-Villiger oxidation of 4-hydroxyacetophenone to the corresponding acetate ester. Using the purified enzyme from recombinant Escherichia coli, we found that a broad range of carbonylic compounds that are structurally more or less similar to 4-hydroxyacetophenone are also substrates for this flavin-containing monooxygenase. On the other hand, several carbonyl compounds that are substrates for other Baeyer-Villiger monooxygenases (BVMOs) are not converted by HAPMO. In addition to performing Baeyer-Villiger reactions with aromatic ketones and aldehydes, the enzyme was also able to catalyze sulfoxidation reactions by using aromatic sulfides. Furthermore, several heterocyclic and aliphatic carbonyl compounds were also readily converted by this BVMO. To probe the enantioselectivity of HAPMO, the conversion of bicyclohept-2-en-6-one and two aryl alkyl sulfides was studied. The monooxygenase preferably converted (1R,5S)-bicyclohept-2-en-6-one, with an enantiomeric ratio (E) of 20, thus enabling kinetic resolution to obtain the (1S,5R) enantiomer. Complete conversion of both enantiomers resulted in the accumulation of two regioisomeric lactones with moderate enantiomeric excess (ee) for the two lactones obtained [77% ee for (1S,5R)-2 and 34% ee for (1R,5S)-3]. Using methyl 4-tolyl sulfide and methylphenyl sulfide, we found that HAPMO is efficient and highly selective in the asymmetric formation of the corresponding (S)-sulfoxides (ee >99%). The biocatalytic properties of HAPMO described here show the potential of this enzyme for biotechnological applications. 相似文献
165.
Scotson Callum P. van Veelen Arjen Williams Katherine A. Koebernick Nicolai McKay Fletcher Dan Roose Tiina 《Plant and Soil》2021,460(1-2):647-665
Plant and Soil - We sought to develop a novel experimental system which enabled application of iodinated contrast media to in vivo plant roots intact in soil and was compatible with time-resolved... 相似文献
166.
167.
Sanne R. Martens-de Kemp Simone U. Dalm Fiona M. J. Wijnolts Arjen Brink Richard J. Honeywell Godefridus J. Peters Boudewijn J. M. Braakhuis Ruud H. Brakenhoff 《PloS one》2013,8(4)
Purpose
The combination of systemic cisplatin with local and regional radiotherapy as primary treatment of head and neck squamous cell carcinoma (HNSCC) leads to cure in approximately half of the patients. The addition of cisplatin has significant effects on outcome, but despite extensive research the mechanism underlying cisplatin response is still not well understood.Methods
We examined 19 HNSCC cell lines with variable cisplatin sensitivity. We determined the TP53 mutational status of each cell line and investigated the expression levels of 11 potentially relevant genes by quantitative real-time PCR. In addition, we measured cisplatin accumulation and retention, as well as the level of platinum-DNA adducts.Results
We found that the IC50 value was significantly correlated with the platinum-DNA adduct levels that accumulated during four hours of cisplatin incubation (p = 0.002). We could not find a significant correlation between cisplatin sensitivity and any of the other parameters tested, including the expression levels of established cisplatin influx and efflux transporters. Furthermore, adduct accumulation did not correlate with mRNA expression of the investigated influx pumps (CTR1 and OCT3) nor with that of the examined DNA repair genes (ATR, ATM, BRCA1, BRCA2 and ERCC1).Conclusion
Our findings suggest that the cisplatin-DNA adduct level is the most important determinant of cisplatin sensitivity in HNSCC cells. Imaging with radio-labeled cisplatin might have major associations with outcome. 相似文献168.
A large body of work has focused on children’s ability to attribute mental states to other people, and whether these abilities are influenced by the extent and nature of children’s social interactions. However, it remains largely unknown which developmental factors shape children’s ability to influence the mental states of others. Building on the suggestion that collaborative experiences early in life might be crucial for the emergence of mental coordination abilities, here we assess the relative contribution of social exposure to familial and non-familial agents on children’s communicative adjustments to their mental model of an addressee (‘audience design’). During an online interactive game, five-year-olds spontaneously organized their non-verbal communicative behaviors according to their beliefs about an interlocutor. The magnitude of these communicative adjustments was predicted by the time spent at daycare, from birth until four years of age, over and above effects of familial social environment. These results suggest that the degree of non-familial social interaction early in life modulates the influence that children’s beliefs have on their referential communicative behavior. 相似文献
169.
McGrath AP Mithieux SM Collyer CA Bakhuis JG van den Berg M Sein A Heinz A Schmelzer C Weiss AS Guss JM 《Biochemistry》2011,50(25):5718-5730
Aspergillus nidulans amine oxidase (ANAO) has the unusual ability among the family of copper and trihydroxyphenylalanine quinone-containing amine oxidases of being able to oxidize the amine side chains of lysine residues in large peptides and proteins. We show here that in common with the related enzyme from the yeast Pichia pastoris, ANAO can promote the cross-linking of tropoelastin and oxidize the lysine residues in α-casein proteins and tropoelastin. The crystal structure of ANAO, the first for a fungal enzyme in this family, has been determined to a resolution of 2.4 ?. The enzyme is a dimer with the archetypal fold of a copper-containing amine oxidase. The active site is the most open of any of those of the structurally characterized enzymes in the family and provides a ready explanation for its lysine oxidase-like activity. 相似文献
170.
Raho N Ramirez L Lanteri ML Gonorazky G Lamattina L ten Have A Laxalt AM 《Journal of plant physiology》2011,168(6):534-539
Nitric oxide (NO) and the lipid second messenger phosphatidic acid (PA) are involved in plant defense responses during plant-pathogen interactions. NO has been shown to be involved in the induction of PA production in response to the pathogen associated molecular pattern (PAMP) xylanase in tomato cells. It was shown that NO is critical for PA production induced via phospholipase C (PLC) in concerted action with diacylglycerol kinase (DGK) but not for the xylanase-induced PA via phospholipase D (PLD). In order to study whether this is a general phenomenon during PAMP perception or if it is particular for xylanase, we studied the effect of the PAMP chitosan in tomato cell suspensions. We observed a rapid NO production in tomato cells treated with chitosan. Chitosan induced the formation of PA by activating both PLD and PLC/DGK. The activation of either phospholipase-mediated signaling pathway was inhibited in cells treated with the NO scavenger cPTIO. This indicates that NO is required for PA generation via both the PLD and PLC/DGK pathway during plant defense response in chitosan elicited cells. Responses downstream PA were studied. PLC inhibitors neomycin and U73122 inhibited chitosan-induced ROS production. Differences between xylanase and chitosan-induced phospholipid signaling pathways are discussed. 相似文献