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31.
Payal Patwari Veronika Salewski Katharina Gutbrod Tino Kreszies Brigitte Dresen‐Scholz Helga Peisker Ulrike Steiner Andreas J. Meyer Lukas Schreiber Peter Drmann 《The Plant journal : for cell and molecular biology》2019,98(4):727-744
Waxes are components of the cuticle covering the aerial organs of plants. Accumulation of waxes has previously been associated with protection against water loss, therefore contributing to drought tolerance. However, not much information is known about the function of individual wax components during water deficit. We studied the role of wax ester synthesis during drought. The wax ester load on Arabidopsis leaves and stems was increased during water deficiency. Expression of three genes, WSD1, WSD6 and WSD7 of the wax ester synthase/diacylglycerol acyltransferase (WS/DGAT or WSD) family was induced during drought, salt stress and abscisic acid treatment. WSD1 has previously been identified as the major wax ester synthase of stems. wsd1 mutants have shown reduced wax ester coverage on leaves and stems during normal or drought condition, while wax ester loads of wsd6, wsd7 and of the wsd6wsd7 double mutant were unchanged. The growth and relative water content of wsd1 plants were compromised during drought, while leaf water loss of wsd1 was increased. Enzyme assays with recombinant proteins expressed in insect cells revealed that WSD6 and WSD7 contain wax ester synthase activity, albeit with different substrate specificity compared with WSD1. WSD6 and WSD7 localize to the endoplasmic reticulum (ER)/Golgi. These results demonstrated that WSD1 is involved in the accumulation of wax esters during drought, while WSD6 and WSD7 might play other specific roles in wax ester metabolism during stress. 相似文献
32.
C-Photosynthate Partitioning and Translocation in Soybeans during Reproductive Development 下载免费PDF全文
Partitioning and translocation of 14C-photosynthates were examined during flowering and seed maturation in soybean (Glycine max [L.]Merr.) plants to quantify allocation to sugars, amino acids, organic acids, and starch and to study transport of C and N from leaves to reproductive sinks. The trifoliolate leaf at the eighth node was exposed to steady state levels of 14CO2 for 2 hours, followed by immediate extraction and identification of radioactive assimilates in the fed leaf blade, tissues of the transport path (e.g. petiole and stem), and fruits if they were present. About one-third of the total 14C recovered from the leaf blades was in starch until late pod-filling, after which the proportion dropped to 16%. Sugars comprised 70% to 86% of the recovered 14C from soluble assimilates of the source leaf, with highest proportions occurring during late flowering and early pod-filling. Amino acids accounted for 8% to 17% of the 14C recovered from the soluble fraction, and were most evident during early flowering and mid to late pod-filling. The 14C-organic acids comprised from 3% to 14% of the soluble 14C-assimilates in leaves. Petioles consistently contained a higher percentage of recovered radioactivity in sugars (87-97%) and a lower percentage in amino acids (3-12%) than did leaf blades. 14C-Amino acids in petioles attained their highest levels during mid and late pod-filling, while 14C-organic acids comprised 2% or less of the recovered radioactivity after pod initiation. The distribution of 14C-assimilates in the internode below the source leaf was similar to that found in petioles. A comparison of the above data to calculated C and N requirements for seed development suggests that 14C-amino acids derived from current photosynthesis and translocated from source leaves supply at least 12% to 48% of the seed N depending on the stage of pod-filling. 相似文献
33.
Anita Kloss-Brandst?tter Hansi Weissensteiner Gertraud Erhart Georg Sch?fer Lukas Forer Sebastian Sch?nherr Dominic Pacher Christof Seifarth Andrea St?ckl Liane Fendt Irma Sottsas Helmut Klocker Christian W. Huck Michael Rasse Florian Kronenberg Frank R. Kloss 《PloS one》2015,10(8)
Background
Oral squamous cell carcinoma (OSCC) is mainly caused by smoking and alcohol abuse and shows a five-year survival rate of ~50%. We aimed to explore the variation of somatic mitochondrial DNA (mtDNA) mutations in primary oral tumors, recurrences and metastases.Methods
We performed an in-depth validation of mtDNA next-generation sequencing (NGS) on an Illumina HiSeq 2500 platform for its application to cancer tissues, with the goal to detect low-level heteroplasmies and to avoid artifacts. Therefore we genotyped the mitochondrial genome (16.6 kb) from 85 tissue samples (tumors, recurrences, resection edges, metastases and blood) collected from 28 prospectively recruited OSCC patients applying both Sanger sequencing and high-coverage NGS (~35,000 reads per base).Results
We observed a strong correlation between Sanger sequencing and NGS in estimating the mixture ratio of heteroplasmies (r = 0.99; p<0.001). Non-synonymous heteroplasmic variants were enriched among cancerous tissues. The proportions of somatic and inherited variants in a given gene region were strongly correlated (r = 0.85; p<0.001). Half of the patients shared mutations between benign and cancerous tissue samples. Low level heteroplasmies (<10%) were more frequent in benign samples compared to tumor samples, where heteroplasmies >10% were predominant. Four out of six patients who developed a local tumor recurrence showed mutations in the recurrence that had also been observed in the primary tumor. Three out of five patients, who had tumor metastases in the lymph nodes of their necks, shared mtDNA mutations between primary tumors and lymph node metastases. The percentage of mutation heteroplasmy increased from the primary tumor to lymph node metastases.Conclusions
We conclude that Sanger sequencing is valid for heteroplasmy quantification for heteroplasmies ≥10% and that NGS is capable of reliably detecting and quantifying heteroplasmies down to the 1%-level. The finding of shared mutations between primary tumors, recurrences and metastasis indicates a clonal origin of malignant cells in oral cancer. 相似文献34.
Membrane-bound neuregulin1 type III actively promotes Schwann cell differentiation of multipotent Progenitor cells 总被引:4,自引:0,他引:4
Many steps of peripheral glia development appear to be regulated by neuregulin1 (NRG1) signaling but the exact roles of the different NRG1 isoforms in these processes remain to be determined. While glial growth factor 2 (GGF2), a NRG1 type II isoform, is able to induce a satellite glial fate in neural crest stem cells, targeted mutations in mice have revealed a prominent role of NRG1 type III isoforms in supporting survival of Schwann cells at early developmental stages. Here, we investigated the role of NRG1 isoforms in the differentiation of Schwann cells from neural crest-derived progenitor cells. In multipotent cells isolated from dorsal root ganglia, soluble NRG1 isoforms do not promote Schwann cell features, whereas signaling by membrane-associated NRG1 type III induces the expression of the Schwann cell markers Oct-6/SCIP and S100 in neighboring cells, independent of survival. Thus, axon-bound NRG1 might actively promote both Schwann cell survival and differentiation. 相似文献
35.
The agonist binding affinity of nicotinic acetylcholine receptor (nAChR) from electroplax, as inferred from ability of agonist to inhibit specific curaremimetic neurotoxin binding to nAChR, is sensitive to the duration of exposure to agonist. The concentration of carbachol necessary to prevent one-half of toxin binding over a 30 min incubation with nAChR (K30) is 10 μM when toxin and carbachol are simultaneously added to membrane-bound nAChR, and 3 μM when nAChR are pretreated with carbachol for 30 min prior to the addition of toxin. These alterations in agonist affinity may be mimicked by modification of nAChR thiol groups. Affinity of nAChR for carbachol is decreased following treatment with dithiothreitol (DTT). Dithio-bis-nitrobenzoic acid treatment of DTT-reduced membranes yields K30 values of 5 μM for carbachol, while N-ethylmaleimide treatment of DTT-reduced nAChR produces nAChR with reduced affinity for carbachol, reflected in K30 values of about 400 μM. In the absence of Ca++, K30 values for carbachol binding to native and DTT-reduced nAChR are diminished 3–6 fold. These affinity alterations are not observed with d-tubocurarine (antagonist) binding to nAChR. Thus, Ca++ and the oxidation state of nAChR thiols appear to affect the affinity of nAChR for agonists (but not antagonists), and may therefore be related to agonist-mediated events in receptor activation and/or desensitization. 相似文献
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Migrating birds perform extraordinary endurance flights, up to 200 h non-stop, at a very high metabolic rate and while fasting. Such an intense and prolonged physical activity is normally associated with an increased production of reactive oxygen and nitrogen species (RONS) and thus increased risk of oxidative stress. However, up to now it was unknown whether endurance flight evokes oxidative stress. We measured a marker of oxidative damage (protein carbonyls, PCs) and a marker of enzymatic antioxidant capacity (glutathione peroxidase, GPx) in the European robin (Erithacus rubecula), a nocturnal migrant, on its way to the non-breeding grounds. Both markers were significantly higher in European robins caught out of their nocturnal flight than in conspecifics caught during the day while resting. Independently of time of day, both markers showed higher concentrations in individuals with reduced flight muscles. Adults had higher GPx concentrations than first-year birds on their first migration. These results show for the first time that free-flying migrants experience oxidative stress during endurance flight and up-regulate one component of antioxidant capacity. We discuss that avoiding oxidative stress may be an overlooked factor shaping bird migration strategies, e.g. by disfavouring long non-stop flights and an extensive catabolism of the flight muscles. 相似文献
40.
Barbara Kiesewetter Julius Lukas Andreas Kuchar Marius E. Mayerhoefer Berthold Streubel Heimo Lagler Leonhard Müllauer Stefan W?hrer Julia Fischbach Markus Raderer 《PloS one》2014,9(7)