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21.
Watts-Williams Stephanie J. Tyerman Stephen D. Cavagnaro Timothy R. 《Plant and Soil》2017,420(1-2):375-388
Plant and Soil - Colonisation of roots by arbuscular mycorrhizal fungi (AMF) can increase plant biomass and nutrition under soil zinc (Zn) deficiency and toxicity conditions, but the genes and... 相似文献
22.
Roles of Aquaporins in Root Responses to Irrigation 总被引:1,自引:0,他引:1
Rebecca Vandeleur Christa Niemietz Joanne Tilbrook Stephen D. Tyerman 《Plant and Soil》2005,274(1-2):141-161
Due to current environmental issues concerning the use of water for irrigation, the improvement of crop water-use efficiency
and a reduction in water consumption has become a priority. New irrigation methods that reduce water use, while still maintaining
production have been developed. To optimise these techniques knowledge of above- and below-ground plant physiological responses
is necessary. During growth, plant roots are exposed to cycles of wetting and drying in normal rain-fed and irrigation situations.
This review concentrates on the below-ground aspects, in particular the water permeability of
roots. Significant research has been conducted on the root anatomy and hydraulic conductivity of desert plants subjected to
wetting and drying. Major intrinsic proteins (MIPs), most of which show aquaporin (water-channel) activity are likely to be
involved in balancing the water relations of the plants during water deficit. However, many MIPs seem to allow permeation
of other small neutral solutes and some may allow permeation of ions under certain conditions. The ability of the plant to
rapidly respond to rewetting may be important in maintaining productivity. It has been suggested that aquaporins may be
involved in this rapid response. The down-regulation of the aquaporins during dry conditions can also limit water loss to
the soil, and intrinsic sensitivity of aquaporins to water potential is shown here to be very strong in some cases (NOD26).
However, the response of aquaporins in various plant species to water deficits has been quite varied. Another component of
aquaporin regulation in response to various stresses (hypoxia/anoxia, salinity and chilling) may be related to redistribution
of flow to more favourable regions of the soil. Some irrigation techniques may be triggering these responses. Diurnal fluctuations
of root hydraulic conductance that is related to aquaporin expression seem to match the expected transpirational demands of
the shoot, and it remains to be seen if shoot-to-root signalling may be important in regulation of root aquaporins. If so,
canopy management typical of horticultural crops may impact on root hydraulic conductance. An understanding of the regulation
of aquaporins may assist in the development of improved resistance to water stress and greater efficiency of water use by
taking into account where and when roots best absorb water. 相似文献
23.
24.
Pouncing spider, flying mosquito: blood acquisition increases predation risk in mosquitoes 总被引:2,自引:1,他引:1
Female mosquitoes dramatically increase their mass when bloodfeeding on their hosts. Such an increase could impact mosquitomortality risk by reducing escape speed and/or agility. We usedtwo laboratory-based experiments to test this notion. In thefirst, we allowed mature female Anopheles gambiae mosquitoesto feed from 0 to 4 min and then attacked those females withan artificial predator. We videotaped subsequent escape responseof each mosquito. Analysis of those responses clearly demonstratedan inverse relationship between increased mass and escape speed.In the second experiment, we exposed both blood-engorged andunfed A.gambiae females to single zebra spiders (Salticus scenicus)in small plexiglass cages. Here, we focused on mosquito escapesfrom searching and pouncing spiders. We found that engorgedmosquitoes were three times less likely to escape searchingspiders compared to unfed conspecifics. Thus we conclude thatblood feeding has substantial state-dependent risk both at thehost (experiment 1) and after feeding (experiment 2). Such riskcan be extended to a broad range of taxa. 相似文献
25.
Pascale Simard Hugo Galarneau Sébastien Marois Daniel Rusu Caroline D Hoemann Patrice E Poubelle Hani El-Gabalawy Maria JG Fernandes 《Arthritis research & therapy》2009,11(3):R74-10
Introduction
Osteoarthritis is characterized by the progressive destruction of cartilage in the articular joints. Novel therapies that promote resurfacing of exposed bone in focal areas are of interest in osteoarthritis because they may delay the progression of this disabling disease in patients who develop focal lesions. Recently, the addition of 80% deacetylated chitosan to cartilage microfractures was shown to promote the regeneration of hyaline cartilage. The molecular mechanisms by which chitosan promotes cartilage regeneration remain unknown. Because neutrophils are transiently recruited to the microfracture site, the effect of 80% deacetylated chitosan on the function of neutrophils was investigated. Most studies on neutrophils use preparations of chitosan with an uncertain degree of deacetylation. For therapeutic purposes, it is of interest to determine whether the degree of deacetylation influences the response of neutrophils to chitosan. The effect of 95% deacetylated chitosan on the function of neutrophils was therefore also investigated and compared with that of 80% deacetylated chitosan. 相似文献26.
Grapevine is moderately sensitive to salinity and accumulation of toxic levels of Cl? in leaves is the major reason for salt-induced symptoms. In this study, apoplastic Cl? uptake and transport mechanism(s) were investigated in two grapevine (Vitis sp.) rootstock hybrids differing in salt tolerance; 1103 Paulsen (salt tolerant) and K 51–40 (salt sensitive). Increased external salinity caused high Cl? accumulation in shoots of the salt sensitive K 51–40 in comparison to Paulsen. Measurement of 15NO3 ? net fluxes under high salinity showed that by increasing external Cl? concentrations K 51–40 roots showed reduced NO3 ? accumulation. This was associated with increased accumulation of Cl?. In comparison to Paulsen, K 51–40 showed reduced NO3 ?/Cl? root selectivity with increased salinity, but Paulsen had lower selectivity over the whole salinity range (0–45 mM). To examine if root hydraulic and permeability characterisations accounted for differences between varieties, the root pressure probe was used on excised roots. This showed that the osmotic Lpr was significantly smaller than hydrostatic Lpr, but no obvious difference was observed between the rootstocks. The reflection coefficient (σ) values (0.48–0.59) were the same for both rootstocks, and root anatomical studies showed no obvious difference in apoplastic barriers of the main and lateral roots. Comparing the uptake of Cl? with an apoplastic tracer, PTS (3-hydroxy-5,8,10-pyrentrisulphonic acid), showed that there was no correlation between Cl? and PTS transport. These results indicated that bypass flow of salts to the xylem is the same for both rootstocks (0.77 ± 0.2 and 1.05 ± 0.12 %) and hence pointed to differences in membrane transport to explain difference in Cl? transport to the shoot. 相似文献
27.
Bernard D. Roitberg Ian C. Robertson Jabus G.A. Tyerman 《Entomologia Experimentalis et Applicata》1999,91(1):187-194
We developed state-dependent life-history theory to explain the variance in clutch size decisions made by insect herbivores under a variety of ecological scenarios. An important aspect of our theory is explicit representation of the distribution of host quality and frequency of occurrence. Examination of the theory suggests that clutch size decisions can be highly non-linear with respect to host quality and variability. We then use our theory to explore the potential for bet-hedging strategies to evolve as a function of unpredictable catastrophic events that decimate entire clutches. Our analysis suggests that the benefits to employing such a strategy will frequently be outweighed by costs brought on by delayed oviposition. 相似文献
28.
Purification and characterization of Dolichos lablab lectin 总被引:1,自引:0,他引:1
The mannose/glucose-binding Dolichos lablab lectin (designated DLL) has
been purified from seeds of Dolichos lablab (hyacinth bean) to
electrophoretic homogeneity by affinity chromatography on an ovalbumin-
Sepharose 4B column. The purified lectin gave a single symmetric protein
peak with an apparent molecular mass of 67 kDa on gel filtration
chromatography, and five bands ranging from 10 kDa to 22 kDa upon SDS-PAGE.
N-Terminal sequence analysis of these bands revealed subunit heterogeneity
due to posttranslational proteolytic truncation at different sites mostly
at the carboxyl terminus. The carbohydrate binding properties of the
purified lectin were investigated by three different approaches:
hemagglutination inhibition assay, quantitative precipitation inhibition
assay, and ELISA. On the basis of these studies, it is concluded that the
Dolichos lablab lectin has neither an extended carbohydrate combining site,
nor a hydrophobic binding site adjacent to it. The carbohydrate combining
site of DLL appears to most effectively accommodate a nonreducing terminal
alpha-d-mannosyl unit, and to be complementary to the C-3, C-4, and C-6
equatorial hydroxyl groups of alpha-d-mannopyranosyl and
alpha-d-glucopyranosyl residues. DLL strongly precipitates murine IgM but
not IgG, and the recent finding that this lectin interacts specifically
with NIH 3T3 fibroblasts transfected with the Flt3 tyrosine kinase receptor
and preserves human cord blood stem cells and progenitors in a quiescent
state for prolonged periods in culture, make this lectin a valuable tool in
biomedical research.
相似文献
29.
30.
Cecilia JG de Almeida Jean-Fran?ois Jasmin Francesco Del Galdo Michael P Lisanti 《Cell cycle (Georgetown, Tex.)》2013,12(14):2248-2254
Caveolar domains act as platforms for the organization of molecular complexes involved in signal transduction. Caveolin proteins, the principal structural components of caveolae, have been involved in many cellular processes. Caveolin-1 (Cav-1) and caveolin-2 (Cav-2) are highly expressed in the lung. Cav-1-deficient mice (Cav-1−/−) and Cav-2-deficient mice (Cav-2−/−) exhibit severe lung dysfunction attributed to a lack of Cav-2 expression. Recently, Cav-1 has been shown to regulate lung fibrosis in different models. Here, we show that Cav-2 is also involved in modulation of the fibrotic response, but through distinct mechanisms. Treatment of wild-type mice with the pulmonary fibrosis-inducer bleomycin reduced the expression of Cav-2 and its phosphorylation at tyrosine 19. Importantly, Cav-2−/− mice, but not Cav-1−/− mice, were more sensitive to bleomycin-induced lung injury in comparison to wild-type mice. Bleomycin-induced lung injury was characterized by alveolar thickening, increase in cell density, and extracellular matrix deposition. The lung injury observed in bleomycin-treated Cav-2−/− mice was not associated with alterations in the TGF-β signaling pathway and/or in the ability to produce collagen. However, apoptosis and proliferation were more prominent in lungs of bleomycin-treated Cav-2−/− mice. Since Cav-1−/− mice also lack Cav-2 expression and show a different outcome after bleomycin treatment, we conclude that Cav-1 and Cav-2 have distinct roles in bleomycin induced-lung fibrosis, and that the balance of both proteins determines the development of the fibrotic process. 相似文献