Identification and quantification of cyclolinopeptides in five flaxseed cultivars     

B Gui  YY Shim  RS Datla  PS Covello  SL Stone  MJ Reaney 《Journal of agricultural and food chemistry》2012,60(35):8571-8579

Cyclolinopeptides are a group of naturally occurring hydrophobic cyclic peptides found in flaxseed and flax oil that have immunosuppressive activity. This study describes the measurement of flaxseed cyclolinopeptide concentrations using an internal standard HPLC method. In addition, the concentration of cyclolinopeptides in the seed of Canadian flax cultivars grown at two locations over two years is reported. The data are consistent with the formation of flaxseed cyclolinopeptides from two ribosome-derived precursors. Each precursor protein includes the sequences corresponding to three cyclolinopeptides from which those cyclolinopeptides are presumably derived by precursor processing. The concentrations of cyclolinopeptides C and E, which are encoded by the same gene sequence, are highly correlated, and the concentrations of cyclolinopeptides D, F, and G, which are encoded by a second gene sequence, are also highly correlated. The strong correlation between the cyclolinopeptides arising from the same gene may prove to be important in understanding how peptide concentration is controlled. Additional research may lead to approaches to improve flax either as a platform for peptide production or as a source of oil with improved drying properties and flavor.  相似文献   

Molecular mimicry regulates ABA signaling by SnRK2 kinases and PP2C phosphatases   总被引：1，自引：0，他引：1  

Soon FF  Ng LM  Zhou XE  West GM  Kovach A  Tan MH  Suino-Powell KM  He Y  Xu Y  Chalmers MJ  Brunzelle JS  Zhang H  Yang H  Jiang H  Li J  Yong EL  Cutler S  Zhu JK  Griffin PR  Melcher K  Xu HE 《Science (New York, N.Y.)》2012,335(6064):85-88

Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.  相似文献   

Factors influencing the survivorship of the burrowing nematode,Radopholus similis (Cobb.) Thorne in two types of soil from banana plantations in Martinique     

Christian Chabrier  Philippe Tixier  Pierre-François Duyck  Céline Carles  Patrick Quénéhervé 《Applied soil ecology》2010,44(2):116-123

The burrowing nematode, Radopholus similis (Cobb.) Thorne, causes the most damage to bananas. To minimize nematicide applications, cropping systems that use fallow, crop rotation and clean planting material have been developed in the French West Indies. In order to optimize the benefit of the intercropping period, we studied the survivorship of R. similis in different soil types and conditions. We monitored the survivorship of calibrated populations of R. similis in the laboratory on a Nitisol and on an Andosol, two soils derived from volcanic ashes and pumices. We studied water potentials ranging from 0 to ?700 kPa on undisturbed soil and on soil previously frozen to get rid of living nematodes. Mortality of adult R. similis decreased regularly, and was fairly well described by Teissier's model. In the previously frozen soils, R. similis survived longer in wet soils (half-life of 21–46 days at 0 to ?5 kPa) than in dry soils (half-life of less than 10 days between ?80 and ?250 kPa). In contrast, in undisturbed soils, R. similis survived longer in dry soils: half-lives ranged from 57 days at ?273 kPa to 17 days at water saturation in the Andosol, and 36 days at ?660 kPa to 14 days at water saturation in the Nitisol. These results are consistent with the absence of anhydrobiosis in R. similis, unlike Pratylenchus coffeae. P. coffeae survivorship curves over time do not follow a model derived from exponential decrease like Teissier's model. These results also show that the recommended one year host-free period required to sanitize soils cannot be shortened without risk, even if flooding the soil could improve it.  相似文献   

From shallow to deep waters: habitats used by larval lampreys (genus Petromyzon and Lampetra) over a western European basin     

Catherine Taverny  Isabelle Ortusi  Charles Roqueplo  Mario Lepage  Patrick Lambert 《Ecology of Freshwater Fish》2012,21(1):87-99

Abstract –  Habitat requirements of lamprey ammocoetes (Petromyzon marinus and Lampetra genus) were investigated, for the first time, from shallow to deep waters, at different spatial scales across the Gironde‐Dordogne continuum, thanks to a water suction dredge. Fish‐habitat relationships were assessed through two complementary statistical analyses: habitat‐use curves and habitat suitability models using the Boosted Regression Trees (BRT) technique. Analyses were performed on a small‐size data set that was characterised by the low prevalence of lamprey. The sea lamprey larvae occurred in deeper areas than their Lampetra genus counterparts. ‘Pools’ of 2 m’ depth and more were optimal habitats for the former species. Among the environmental variables retained to model lamprey occurrences, the mesohabitat (a categorical variable) was demonstrated to be highly influential, in terms of fine grain‐size substratum and vegetation cover. These preliminary results suggest that monitoring using the water suction dredge method may contribute to sea lamprey conservation.  相似文献   

Pamela Walker: Growing good things to eat in Texas: Profiles of organic farmers and ranchers across the state     

Patrick T. Lillard 《Agriculture and Human Values》2010,27(4):527-528

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Biological effects and metabolism of fenoxycarb after treatment of the fourth and the fifth instars of the tobacco budworm,Heliothis virescens F.     

Bernard Mauchamp  Christian Malosse  Patrick Saroglia 《Pest management science》1989,26(3):283-301

Treatment of 4th and 5th instar larvae of Heliothis virescens with different amounts of fenoxycarb induced an increase in weight of the 5th larval instar, prolongation of the 5th larval instar period, or the formation of dauer larvae. No effects were observed during the 4th instar and the moult to the 5th larval instar. To check whether these effects were due to persistence of fenoxycarb in treated larvae, metabolism of this chemical was analysed. Larvae were fed with radio-labelled fenoxycarb at the first day of the 4th or at the first day of the 5th larval instar. Behaviour of the radio-labelled compounds was followed during each instar. At the time of gut purge, the whole of the radio-labelled material was excreted. The effects observed during the 5th instar of 4th-instar-treated larvae do not appear to be due to the persistence of fenoxycarb. The main metabolites of fenoxycarb were identified using coupled gas chromatography and mass spectrometry.  相似文献   

Uptake and utilisation of phosphonate ions by Phytophthora citrophthora and Nectria haematococca in relation to their selective toxicity     

Thierry Barchietto  Patrick Saindrenan  Gilbert Bompeix 《Pest management science》1988,22(2):159-167

Phosphonate ions, which are degradation products of aluminium tris-O-ethyl phosphonate (fosetyl-aluminium) in plant tissues, had more effect in vitro against Phytophthora citrophthora than against Nectria haematococca. Both fungi were able to take up phosphonate ions. This uptake was realised against a concentration gradient and was affected by metabolic inhibitors. When examined over a 0.5 to 6.0 mm concentration range, phosphonate was carried by a single transport process obeying Michaelis-Menten kinetics, with a low affinity (high K′_m). Further analysis by means of Hofstee plots indicated a somewhat faster phosphonate uptake by N. haematococca than by P. citrophthora, so it appears clearly that uptake was not involved in the selective toxicity of this compound. The continuous uptake of phosphonate by N. haematococca is correlated with an important utilisation of this ion by the fungal cells. This fact could be explained by a detoxification process corresponding to the oxidation of phosphonate to phosphate which could account for the low sensitivity of this fungus. Phosphonate uptake by P. citrophthora reached a maximum level after 20 min and then decreased to a constant level over the following period. During the incubation period phosphonate was incorporated directly without oxidation into phosphate. This incorporation could lead to a disturbance of the cell metabolism.  相似文献   

Distribution of glyphosate and of its target enzyme inside wheat plants     

Laurence Arnaud  Franoise Nurit  Patrick Ravanel  Michel Tissut 《Pest management science》1994,40(3):217-223

Enolpyruvylshikimate phosphate (EPSP) synthase activity has been measured in different organs of 1–14-day-old wheat seedlings growing in culture chambers. Enzyme activity was first detected after two days, and reached its maximum value at day 4. It remained almost unchanged for 14 days thereafter. During germination, one of the most important sources of enzyme was the seed scutellum. Later, the developed leaves contained 43% of the whole stock of enzyme. Although the enzyme distribution was not identical under light or in the dark, there was no evident light induction of EPSP synthase. High enzyme activity was found in the coleoptile, continuing for the whole life-time of this organ, and which might be associated with its lignification. Five to 40% of the total enzyme was found in the roots, reaching a maximum at 14 days. At this stage, glyphosate applied to the first grown leaf was phloem-transported to the sink organs, with no clear relationship being shown between EPSP synthase activity and herbicide quantity in each organ. At day 4, glyphosate treatment, by soaking the seedlings in the herbicide solution, was followed by an active phloem transport from the scutellum to the growing parts. The average internal concentration of radiolabelled compounds (glyphosate plus its possible derivatives) which induced wheat seedling growth decrease, was shown to reach 50 to 100 μM under our conditions.  相似文献   

The Role of the Bark Beetle, Hylastes ater (Coleoptera: Scolytidae), as a Sapstain Fungi Vector to Pinus radiata Seedlings: A Crisis for the New Zealand Forestry Industry?     

Stephen D. Reay  Joanne M. Thwaites  Roberta L. Farrell  Patrick J. Walsh 《Integrated Pest Management Reviews》2001,6(3-4):283-291

The role of the bark beetle Hylastes ater in the re-establishment of Pinus radiata forest in New Zealand is discussed. H. ater was found to be a dominant factor in seedlings mortality in the first year following planting. However, seedling mortality is usually relatively low. In contrast, it was found the large numbers of seedlings were sub-lethally damaged by H. ater feeding attempts, particularly in high risk sites. High risk sites were identified as sites that were harvested during March and April (autumn) when the peak flight activity of H. ater occurred, and subsequently planted with P. radiata seedlings the following winter. H. ater was found to vector sapstain fungi to seedlings during feeding attempts, and a strong relationship between the severity of damage and presence of sapstain fungi was identified. The role of H. ater as a vector of these fungi and the potential implications to the New Zealand forest industry are discussed.  相似文献   

Evaluation of PCR,IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales     

Said K Ibrahim  Stephen T Minnis  Anthony D P Barker  Mike D Russell  Patrick P J Haydock  Kenneth Evans  Ivan G Grove  Simon R Woods  Andrew Wilcox 《Pest management science》2001,57(11):1068-1074

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4–6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given. © 2001 Society of Chemical Industry  相似文献