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排序方式: 共有187条查询结果,搜索用时 15 毫秒
161.
DARJA STANI RACMAN KARA MCGEACHY BRIAN REAVY BORUT TRUKELJ JANA EL HUGH BARKER 《The Annals of applied biology》2001,139(2):269-275
The potato cv. Igor is susceptible to infection with Potato virus Y (PVY) and in Slovenia it has been so severely affected with NTN isolates of PVY causing potato tuber necrotic ringspot disease (PTNRD) that its cultivation has ceased. Plants of cv. Igor were transformed with two transgenes that contained coat protein gene sequence of PVYNTN. Both transgenes used PVY sequence in a sense (+) orientation, one in native translational context (N‐CP), and one with a frame‐shift mutation (FS‐CP). Although most transgenic lines were susceptible to infection with PVYNTN and PVYO, several lines showed resistance that could be classified into two types. Following manual or graft inoculation, plants of partially resistant lines developed some symptoms in foliage and tubers, and virus titre in the foliage, estimated by ELISA, was low or undetectable. In highly resistant (R) lines, symptoms did not develop in foliage and on tubers, and virus could not be detected in foliage by ELISA or infectivity assay. Four lines from 34 tested (two N‐CP and two FS‐CP) were R to PVYNTN and PVYO and one additional line was R to PVYO. When cv. Spey was transformed with the same constructs, they did not confer strong resistance to PVYO. 相似文献
162.
163.
Spatial genetic structure (SGS) results from the interplay of several demographical processes that are difficult to tease apart. In this study, we explore the specific effects of seed and pollen dispersal and of early postdispersal mortality on the SGS of a seedling cohort (N = 786) recruiting within and around an expanding pedunculate oak (Quercus robur) stand. Using data on dispersal (derived from parentage analysis) and mortality (monitored in the field through two growing seasons), we decompose the overall SGS of the cohort into its components by contrasting the SGS of dispersed (i.e. growing away from their mother tree) vs. nondispersed (i.e. growing beneath their mother tree) and initial vs. surviving seedlings. Patterns differ strongly between nondispersed and dispersed seedlings. Nondispersed seedlings are largely responsible for the positive kinship values observed at short distances in the studied population, whereas dispersed seedlings determine the overall SGS at distances beyond c. 30 m. The paternal alleles of nondispersed seedlings show weak yet significantly positive kinships up to c. 15 m, indicating some limitations in pollen flow that should further promote pedigree structures at short distances. Seedling mortality does not alter SGS, except for a slight increase in the nondispersed group. Field data reveal that mortality in this group is negatively density‐dependent, probably because of small‐scale variation in light conditions. Finally, we observe a remarkable similarity between the SGS of the dispersed seedlings and that of the adults, which probably reflects dispersal processes during the initial expansion of the population. Overall, this study demonstrates that incorporating individual‐level complementary information into analyses can greatly improve the detail and confidence of ecological inferences drawn from SGS. 相似文献
164.
Espagne E Lespinet O Malagnac F Da Silva C Jaillon O Porcel BM Couloux A Aury JM Ségurens B Poulain J Anthouard V Grossetete S Khalili H Coppin E Déquard-Chablat M Picard M Contamine V Arnaise S Bourdais A Berteaux-Lecellier V Gautheret D de Vries RP Battaglia E Coutinho PM Danchin EG Henrissat B Khoury RE Sainsard-Chanet A Boivin A Pinan-Lucarré B Sellem CH Debuchy R Wincker P Weissenbach J Silar P 《Genome biology》2008,9(5):R77-22
165.
Johanna EL Andaloussi-Lilja Jessica Lundqvist Anna Forsby 《Neurochemistry international》2009,55(8):768-774
The transient receptor potential vanilloid subtype 1 (TRPV1) is a Ca2+-permeable channel primarily expressed in dorsal root ganglion neurons. Besides its function in thermogenic nociception and neurogenic inflammation, TRPV1 is involved in cell migration, cytoskeleton re-organisation and in neuronal guidance. To explore the TRPV1 level and activity during conditions for neuronal maturation, TRPV1-expressing SHSY5Y neuroblastoma cells were differentiated into a neuronal phenotype using all-trans-retinoic acid (RA). We show that RA highly up-regulated the total and cell surface TRPV1 protein expression but the TRPV1 mRNA level was unaffected. The up-regulated receptors were localised to the cell bodies and the developed neurites. Furthermore, RA increased both the basal intracellular free Ca2+ concentration by 30% as well as the relative capsaicin-induced Ca2+ influx. The results show that TRPV1 protein expression increases during RA-induced differentiation in vitro, which generates an altered intracellular Ca2+ homeostasis. 相似文献
166.
Generating somatic embryos from the inner teguments of Heveaseeds is difficult. Like other ligneous plants, the rubber-treeis generally considered to be recalcitrant with regard to somaticembryogenesis. In this paper we show that when conventionallyused amounts of both 3, 4-dichlorophenoxyacetic acid (3, 4-D)and benzylaminopurine (BAP) are reduced by 24 times andwhen the length of exposure to these hormones is also reduced,the embryogenic capacity of calli increases without affectingcallogenesis. The germination of several embryos and plantletswas obtained. We conclude that an excess of auxin and cytokininin the medium, even of a weak auxin such as 3, 4-D, and theprolonged exposure to these hormones suppress the embryogeniccapacity of the callus. Hevea brasiliensis, rubber-tree, somatic embryogenesis, hormones 相似文献
167.
Karine Joubrane André EL Khoury Roger Lteif Toufic Rizk Mireille Kallassy Christo Hilan Richard Maroun 《Mycotoxin Research》2011,27(4):249-257
An extensive survey of filamentous fungi isolated from wheat grown and consumed in Lebanon and their capacity to produce aflatoxin
B1 (AFB1) and ochratoxin A (OTA) was conducted to assess fungi potential for producing these toxins in wheat. From the 468 samples
of wheat kernel, collected at preharvest stage from different locations during 2008 and 2009 cultivation seasons, 3,260 fungi
strains were isolated with 49.4% belonging to Penicillium spp. and 31.2% belonging to Aspergillus spp. Penicillium spp. was detected on wheat samples with a high amount of P. verrucosum (37.0%). Among the different Aspergillus spp. isolated, A. niger aggregate was predominant and constituted 37.3%. whereas the isolation rate of A. flavus and A. ochraceus was 32.2 and 25.6%, respectively. The ability to produce OTA and AFB1 by isolates belonging to Aspergillus spp. and Penicillium spp. was analyzed by high performance liquid chromatography with fluorescence detector (HPLC-FLD). It was found that 57.0%
of Penicillium spp. and 80% of A. ochraceus isolates tested produced OTA, respectively, at maximum concentrations of 53 and 65 μg/g CYA. As for the aflatoxinogenic ability,
45.3% of A. flavus produced AFB1, with maximum concentration of 40 μg/g CYA. A total of 156 wheat samples were analyzed for the levels of OTA and AFB1 by HPLC-FLD. The results showed that 23.7% were contaminated with OTA, at a concentration higher than 3 μg/kg and 35.2% of
these samples were contaminated with AFB1 at concentration higher than 2 μg/kg. The risks originating from toxin levels in wheat produced in Lebanon should be monitored
to prevent their harmful effects on public health. 相似文献
168.
Choline acetyltransferase activity of spinal cord cell cultures increased by co-culture with muscle and by muscle-conditioned medium 总被引:6,自引:3,他引:6 下载免费PDF全文
Activity of the enzyme choline acetyltransferase (CAT), which mediates the synthesis of the neurotransmitter, acetylcholine, was increased up to 20- fold in spinal cord (SC) cells grown in culture with muscle cells for 2 wk. This increase was directly related to the duration of co-culture as well as to the cell density of both the SC and muscle involved and was not affected by the presence of the acetylcholine receptor blocking agent, α-bungarotoxin. Glutamic acid decarboxylase (GAD) activity was often markedly decreased in SC-muscle cultures while the activities of acetylcholinesterase and several other enzymes were little changed. Increased CAT activity was also observed when SC cultures were maintained in medium which had been conditioned by muscle cells or by undifferentiated cells from embryonic muscle. Muscle-conditioned medium (CM) did not affect the activities of SC cell GAD or acetylcholinesterase. Dilution or concentration of the CM directly affected its ability to increase SC CAT activity , as did the duration and timing of exposure of the SC cells to the CM. The medium could be conditioned by muscle cells in the presence or absence of serum, and remained effective after dialysis or heating to 58 degrees C. Membrane filtration data were consistent with the conclusion that the active material(s) in CM had a molecular weight in excess of 50,000 daltons. We conclude that large molecular weight material that is released by muscle cells is capable of producing a specific increase in CAT activity of SC cells. 相似文献
169.
170.
MAŁGORZATA PILOT MICHAŁ J. DĄBROWSKI ELŻBIETA JANCEWICZ NICOLAS SCHTICKZELLE JOANNA GLIWICZ 《Molecular ecology》2010,19(13):2800-2812
Genetic variability, kin structure and demography of a population are mutually dependent. Population genetic theory predicts that under demographically stable conditions, neutral genetic variability reaches equilibrium between gene flow and drift. However, density fluctuations and non‐random mating, resulting e.g. from kin clustering, may lead to changes in genetic composition over time. Theoretical models also predict that changes in kin structure may affect aggression level and recruitment, leading to density fluctuations. These predictions have been rarely tested in natural populations. The aim of this study was to analyse changes in genetic variability and kin structure in a local population of the root vole (Microtus oeconomus) that underwent a fourfold change in mean density over a 6‐year period. Intensive live‐trapping resulted in sampling 88% of individuals present in the study area, as estimated from mark–recapture data. Based on 642 individual genotypes at 20 microsatellite loci, we compared genetic variability and kin structure of this population between consecutive years. We found that immigration was negatively correlated with density, while the number of kin groups was positively correlated with density. This is consistent with theoretical predictions that changes in kin structure play an important role in population fluctuations. Despite the changes in density and kin structure, there was no genetic differentiation between years. Population‐level genetic diversity measures did not significantly vary in time and remained relatively high (HE range: 0.72–0.78). These results show that a population that undergoes significant demographic and social changes may maintain high genetic variability and stable genetic composition. 相似文献