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1.
Widiez T Hartman TG Dudai N Yan Q Lawton M Havkin-Frenkel D Belanger FC 《Plant molecular biology》2011,76(6):475-488
Caffeoyl CoA O-methyltransferases (OMTs) have been characterized from numerous plant species and have been demonstrated to be involved in
lignin biosynthesis. Higher plant species are known to have additional caffeoyl CoA OMT-like genes, which have not been well
characterized. Here, we identified two new caffeoyl CoA OMT-like genes by screening a cDNA library from specialized hair cells
of pods of the orchid Vanilla planifolia. Characterization of the corresponding two enzymes, designated Vp-OMT4 and Vp-OMT5, revealed that in vitro both enzymes preferred
as a substrate the flavone tricetin, yet their sequences and phylogenetic relationships to other enzymes are distinct from
each other. Quantitative analysis of gene expression indicated a dramatic tissue-specific expression pattern for Vp-OMT4, which was highly expressed in the hair cells of the developing pod, the likely location of vanillin biosynthesis. Although
Vp-OMT4 had a lower activity with the proposed vanillin precursor, 3,4-dihydroxybenzaldehyde, than with tricetin, the tissue
specificity of expression suggests it may be a candidate for an enzyme involved in vanillin biosynthesis. In contrast, the
Vp-OMT5 gene was mainly expressed in leaf tissue and only marginally expressed in pod hair cells. Phylogenetic analysis suggests
Vp-OMT5 evolved from a cyanobacterial enzyme and it clustered within a clade in which the sequences from eukaryotic species
had predicted chloroplast transit peptides. Transient expression of a GFP-fusion in tobacco demonstrated that Vp-OMT5 was
localized in the plastids. This is the first flavonoid OMT demonstrated to be targeted to the plastids. 相似文献
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3.
Induction of Neurite Outgrowth through Contactin and Nr-CAM by Extracellular Regions of Glial Receptor Tyrosine Phosphatase β 下载免费PDF全文
Takeshi Sakurai Marc Lustig Moshe Nativ John J. Hemperly Joseph Schlessinger Elior Peles Martin Grumet 《The Journal of cell biology》1997,136(4):907-918
Receptor protein tyrosine phosphatase β (RPTPβ) is expressed as soluble and receptor forms with common extracellular regions consisting of a carbonic anhydrase domain (C), a fibronectin type III repeat (F), and a unique region called S. We showed previously that a recombinant Fc fusion protein with the C domain (βC) binds to contactin and supports neuronal adhesion and neurite growth. As a substrate, βCFS was less effective in supporting cell adhesion, but it was a more effective promoter of neurite outgrowth than βCF. βS had no effect by itself, but it potentiated neurite growth when mixed with βCF. Neurite outgrowth induced by βCFS was inhibited by antibodies against Nr-CAM and contactin, and these cell adhesion molecules formed a complex that bound βCFS. NIH3T3 cells transfected to express βCFS on their surfaces induced neuronal differentiation in culture. These results suggest that binding of glial RPTPβ to the contactin/Nr-CAM complex is important for neurite growth and neuronal differentiation. 相似文献
4.
Gabriel Yarmush Lucas Santos Joshua Yarmush Srivathsan Koundinyan Mubasher Saleem Nir I. Nativ Martin L. Yarmush Francois Berthiaume Timothy J. Maguire Chris Guaghan 《Biomechanics and modeling in mechanobiology》2017,16(4):1095-1102
Donor livers available to transplant for patients with end-stage liver disease are in severe shortage. One possible avenue to expand the donor pool is to recondition livers that would be otherwise discarded due to excessive fat content. Severely steatotic livers (also known as fatty livers) are highly susceptible to ischemia-reperfusion injury and as a result, primary liver non-function post-transplantation. Prior studies in isolated perfused rat livers suggest that “defatting” may be possible in a timeframe of a few hours; thus, it is conceivable that fatty liver grafts could be recovered by machine perfusion to clear stored fat from the organ prior to transplantation. However, studies using hepatoma cells and adult hepatocytes made fatty in culture report that defatting may take several days. Because cell culture studies were done in static conditions, we hypothesized that the defatting kinetics are highly sensitive to flow-mediated transport of metabolites. To investigate this question, we experimentally evaluated the effect of increasing flow rate on the defatting kinetics of cultured HepG2 cells and developed an in silico combined reaction-transport model to identify possible rate-limiting steps in the defatting process. We found that in cultured fatty HepG2 cells, the time required to clear stored fat down to lean control cells can be reduced from 48 to 4–6 h by switching from static to flow conditions. The flow required resulted in a fluid shear of .008 Pa, which did not adversely affect hepatic function. The reaction-transport model suggests that the transport of l-carnitine, which is the carrier responsible for taking free fatty acids into the mitochondria, is the key rate-limiting process in defatting that was modulated by flow. Therefore, we can ensure higher levels of l-carnitine uptake by the cells by choosing flow rates that minimize the limiting mass transport while minimizing shear stress. 相似文献
5.
Selected plants within the Origanum, Mentha and Salvia genera, that contain significant amounts of chiral volatile alcohols and their related acetates, exhibit remarkable enantioselectivity of alcohol acetyl transferase (AAT) activity and particularly can discriminate between linalool enantiomers. Origanum dayi AAT produced almost enantiomerically pure (R)-linalyl acetate by enzymatic acetylation of racemic linalool, whereas the closely related O. majorana AAT produced a mixture of (R)- and (S)-linalyl acetate with a ratio of 6:4. V(max) of O. dayi acetylation activity was 30-fold higher for (R)-linalool, whereas in O. majorana no such differences were found. 相似文献
6.
Enantioselectivity of the Bioconversion of Chiral Citronellal during the Inhibition of Wheat Seeds Germination 下载免费PDF全文
Citronellal is one of the most prominent monoterpenes present in many essential oils. Low persistence of essential oils as bioherbicides has often been addressed because of the high volatility of these compounds. Bioconversion of citronellal by wheat seeds releases less aggressive and injurious compounds as demonstrated by their diminished germination. We demonstrated that optically pure citronellal enantiomers were reduced to optically pure citronellol enantiomers with retention of the configuration both in isolated wheat embryos and endosperms. Our findings reveal the potential of essential oils as allelopathic agents providing an insight into their mechanism of action and persistence. 相似文献
7.
Paula Teper-Bamnolker Nativ Dudai Ravit Fischer Eduard Belausov Hanita Zemach Oded Shoseyov Dani Eshel 《Planta》2010,232(1):179-186
Sprouting of potatoes during storage, due to tuber dormancy release, is associated with weight loss and softening. Sprout-preventing
chemicals, such as chlorpropham (CIPC), can negatively impact the environment and human health. Monthly thermal fogging with
mint (Mentha spicata L.) essential oil (MEO) inhibited sprouting in eight potato cultivars during large-volume 6-month storage: the tubers remained
firm with 38% lower weight loss after 140 days of storage. The sprout-inhibitory action may be nullified: treated tubers washed
with water resumed sprouting within days, with reduced apical dominance. MEO application caused local necrosis of the bud
meristem, and a few weeks later, axillary bud (AX) growth was induced in the same sprouting eye. MEO components analysis showed
that 73% of its content is the monoterpene R-carvone. Tubers treated with synthetic R-carvone in equivalent dose, 4.5 μl l−1, showed an inhibitory effect similar to that of MEO. Surprisingly, 0.5 μl l−1 of MEO or synthetic R-carvone catalyzed AX sprouting in the tuber. To the best of our knowledge, this is the first report of an essential oil vapor
inducing early sprouting of potato tubers. R-carvone caused visible damage to the meristem membrane at sprout-inhibiting, but not sprout-inducing doses, suggesting different
underlying mechanisms. After 5 days’ exposure to R-carvone, its derivatives transcarveol and neo-dihydrocarveol were found in buds of tubers treated with the inhibitory dose,
suggesting biodegradation. These experiments demonstrate the potential of MEO vapor as an environmentally friendly alternative
to CIPC in stored potatoes and as a research tool for the control of sprouting in plants. 相似文献
8.
Dudai Nativ; Larkov Olga; Ravid Uzi; Putievsky Eli; Lewinsohn Efraim 《Annals of botany》2001,88(3):349-354
White micromeria [ Micromeria fruticosa(L.) Druce, Lamiaceae]is a dwarf evergreen shrub endemic to Israel and the easternMediterranean. The essential oil of M. fruticosa largely comprisesthe monoterpenes (+)-pulegone and isomenthol. Seasonal variationsin the levels and composition of the monoterpene componentsof the essential oil of M. fruticosa were noted. During thesummer months, when growth rates are maximal, (+)-pulegone constitutedup to 80% of the essential oil, while in early winter, a periodof growth-rest in Mediterranean climates, (+)-pulegone levelsdropped dramatically to a few percent, while isomenthol constitutedup to 80% of the essential oil. Experiments in which plantswere grown under controlled temperature and photoperiodic regimesindicated that the variation was not directly associated withenvironmental conditions, but the composition of the monoterpenesobtained from mature flowering branches was strikingly differentto that obtained from young vegetative branches. Additionally,there were marked differences in the extracts obtained fromindividual leaf pairs from the same plant. In young upper leaves,the main component was (+)-pulegone, constituting up to 70%of the total essential oil extracted. During maturation, levelsof this component dropped steadily, becoming negligible in olderleaves. Reciprocally, levels of isomenthol increased steadilywith leaf position, from 0% in young leaves to more than 60%in older leaves. Less pronounced but significant decreases inthe levels of limonene, isopulegone, piperitenone oxide, germacreneD and bicyclogermacrene, accompanied by increases in neoiso-isopulegol,isopulegol, neoisomenthol and pulegol were noted. This studyindicates that the strong seasonal variation observed in thechemical composition of M. fruticosa is primarily due to leafmaturation. Copyright 2001 Annals of Botany Company Micromeria fruticosa, Lamiaceae, essential oil, leaf age, monoterpenes, (+)-pulegone, isomenthol, pulegol 相似文献
9.
Davidovich-Rikanati R Sitrit Y Tadmor Y Iijima Y Bilenko N Bar E Carmona B Fallik E Dudai N Simon JE Pichersky E Lewinsohn E 《Nature biotechnology》2007,25(8):899-901
We have modified the flavor and aroma of tomatoes by expressing the Ocimum basilicum geraniol synthase gene under the control of the tomato ripening-specific polygalacturonase promoter. A majority of untrained taste panelists preferred the transgenic fruits over controls. Monoterpene accumulation was at the expense of reduced lycopene accumulation. Similar approaches may be applicable for carotenoid-accumulating fruits and flowers of other species. 相似文献
10.
Ilia Goltsman Emad E. Khoury Doron Aronson Omri Nativ Giora Z. Feuerstein Joseph Winaver Zaid Abassi 《Journal of cellular and molecular medicine》2019,23(7):4779-4794
The thiazolidinedione (TZD) class of Peroxisome proliferator‐activated receptor gamma agonists has restricted clinical use for diabetes mellitus due to fluid retention and potential cardiovascular risks. These side effects are attributed in part to direct salt‐retaining effect of TZDs at the renal collecting duct. A recent study from our group revealed that prolonged rosiglitazone (RGZ) treatment caused no Na+/H2O retention or up‐regulation of Na+ transport‐linked channels/transporters in experimental congestive heart failure (CHF) induced by surgical aorto‐caval fistula (ACF). The present study examines the effects of RGZ on renal and cardiac responses to atrial natriuretic peptide (ANP), Acetylcholine (Ach) and S‐Nitroso‐N‐acetylpenicillamine (SNAP‐NO donor). Furthermore, we assessed the impact of RGZ on gene expression related to the ANP signalling pathway in animals with ACF. Rats subjected to ACF (or sham) were treated with either RGZ (30 mg/kg/day) or vehicle for 4 weeks. Cardiac chambers pressures and volumes were assessed invasively via Miller catheter. Kidney excretory and renal hemodynamic in response to ANP, Ach and SNAP were examined. Renal clearance along with cyclic guanosine monophosphate (cGMP), gene expression of renal CHF‐related genes and ANP signalling in the kidney were determined. RGZ‐treated CHF rats exhibited significant improvement in the natriuretic responses to ANP infusion. This ‘sensitization’ to ANP was not associated with increases in neither urinary cGMP nor in vitro cGMP production. However, RGZ caused down‐regulation of several genes in the renal cortex (Ace, Nos3 and Npr1) and up‐regulation of ACE2, Agtrla, Mme and Cftr along down‐regulation of Avpr2, Npr1,2, Nos3 and Pde3 in the medulla. In conclusion, CHF+RGZ rats exhibited significant enhancement in the natriuretic responses to ANP infusion, which are known to be blunted in CHF. This ‘sensitization’ to ANP is independent of cGMP signalling, yet may involve post‐cGMP signalling target genes such as ACE2, CFTR and V2 receptor. The possibility that TZD treatment in uncomplicated CHF may be less detrimental than thought before deserves additional investigations. 相似文献