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971.
Corradi N Croll D Colard A Kuhn G Ehinger M Sanders IR 《Applied and environmental microbiology》2007,73(1):366-369
Gene copy number polymorphism was studied in a population of the arbuscular mycorrhizal fungus Glomus intraradices by using a quantitative PCR approach on four different genomic regions. Variation in gene copy number was found for a pseudogene and for three ribosomal genes, providing conclusive evidence for a widespread occurrence of macromutational events in the population. 相似文献
972.
973.
Sinha J Inan M Fanders S Taoka S Gouthro M Swanson T Barent R Barthuli A Loveless BM Smith LA Smith T Henderson I Ross J Meagher MM 《Journal of biotechnology》2007,127(3):462-474
A process was developed for production of a candidate vaccine antigen, recombinant C-terminal heavy chain fragment of the botulinum neurotoxin serotype E, rBoNTE(H(c)) in Pichia pastoris. P. pastoris strain GS115 was transformed with the rBoNTE(H(c)) gene inserted into pHILD4 Escherichia coli-P. pastoris shuttle plasmid. The clone was characterized for genetic stability, copy number, and BoNTE(H(c)) sequence. Expression of rBoNTE(H(c)) from the Mut(+) HIS4 clone was confirmed in the shake-flask, prior to developing a fed-batch fermentation process at 5 and 19 L scale. The fermentation process consists of a glycerol growth phase in batch and fed-batch mode using a defined medium followed by a glycerol/methanol transition phase for adaptation to growth on methanol and a methanol induction phase resulting in the production of rBoNTE(H(c)). Specific growth rate, ratio of growth to induction phase, and time of induction were critical for optimal rBoNTE(H(c)) production and minimal proteolytic degradation. A computer-controlled exponential growth model was used for process automation and off-gas analysis was used for process monitoring. The optimized process had an induction time of 9 h on methanol and produced up to 3 mg of rBoNTE(H(c)) per gram wet cell mass as determined by HPLC and Western blot analysis. 相似文献
974.
975.
Many herbivores elicit biochemical, physiological, or morphological changes in their host plants that render them more resistant
to co-occurring herbivores. Yet, despite the large number of studies that investigate how induced resistance affects herbivore
preference and performance, very few have simultaneously explored the cascading effects of induction on higher trophic levels
and consequences for prey suppression. In our study system, early-season herbivory by leafhoppers elevated plant resistance
to subsequent attack by chrysomelid beetles sharing the same host plant. Notably, beetles feeding on leafhopper-damaged plants
incurred developmental penalties (e.g., prolonged time in early larval instars) that rendered them more susceptible to predation
by natural enemies. As a result, the combined bottom-up effect of leafhopper-induced resistance and the top-down effect of
enhanced predation resulted in the synergistic suppression of beetle populations. These results emphasize that higher trophic
level dynamics should be considered in conjunction with induced resistance to better understand how plants mediate interspecific
interactions in phytophagous insect communities. 相似文献
976.
Plant growth chambers are commonly used to minimize environmental variation but the light sources used vary considerably from natural light and from each other. Incandescent globes are often used to add more far-red light, with the aim of producing a more natural red to far-red ratio (R:FR), but also add to thermal load. High-intensity discharge lamps are often used to produce higher irradiances, more akin to natural light, but the thermal implications are rarely considered because air temperature is controlled. This paper examines the spectral properties and thermal implications of growth chamber light sources and takes a whole-plant physiology approach, by examining growth responses of a photoperiodic pea line ( Pisum sativum L. cv. Torsdag) in the same growth chamber type under different light sources – in essence using plants to study the controlled environments rather than vice-versa. High R:FR delayed flowering and inhibited internode extension in pea. However, the addition of far-red-rich incandescent globes in the proportions provided in the growth chambers (400–500 W) did little to reduce R:FR, did not induce earlier flowering and actually further inhibited internode length. Leaflet size and yield were significantly reduced. While air temperature was maintained at 20°C in all experiments, radiant temperature was significantly higher under high irradiance and/or with incandescent added, and soil temperatures were elevated. Growth responses under these lights were similar to the effect caused by elevating the air temperature. An alternative method of controlling R:FR, without thermal load implications, using light-emitting diodes is described. 相似文献
977.
Does carbon partitioning in ectomycorrhizal pine seedlings under elevated CO2 vary with fungal species? 总被引:1,自引:1,他引:0
Enhanced soil respiration in response to elevated atmospheric CO2 has been demonstrated, and ectomycorrhizal (ECM) fungi are of particular interest since they partition host-derived photoassimilates
belowground. Although a strong response of ECM fungi to elevated CO2 has been shown, little is still known about the functional diversity among species. We studied carbon (C) partitioning in
mycorrhizal Scots pine seedlings in response to short-term CO2 enrichment, using seven ECM species with different ecological strategies. Mycorrhizal associations were synthesised and seedlings
grown in large Petri dishes containing peat:vermiculite and nutrient solution for 10–15 weeks, after which half of the microcosms
were exposed to elevated CO2 treatment (710 ppm) for 15 days and the other half were kept in ambient CO2 treatment. Partitioning of C was quantified by pulse labelling the seedlings with 14CO2 and examining the distribution of labelled assimilates in shoot, root and extraradical mycelial compartments by destructive
harvest and liquid scintillation counting. Fungal biomass was determined with PLFA analysis. The respiratory loss of 14CO2 was on average greater in the elevated CO2 treatment for most species compared to the ambient CO2 treatment. More label was retrieved in the shoots in the ambient CO2 treatment compared to elevated CO2 (significant for P. involutus and P. fallax). Greater amounts of label were found in the extraradical mycelial compartment in all species (except P. involutus) in elevated CO2 compared to ambient CO2 (significant for L. bicolor, P. byssinum, P. fallax and R. roseolus). Fungal biomass production increased significantly with elevated CO2 for two species (H. velutipes and A. muscaria); three species (P. fallax, P. involutus and R. roseolus) showed a similar but non-significant trend, whereas L. bicolor and P. byssinum produced less biomass in elevated CO2 compared to ambient CO2. When 14C in the mycelial compartment and respiration was expressed per unit fungal PLFA the difference between CO2 treatments disappeared. We demonstrated that different ECM fungal isolates respond differently in C partitioning in response
to CO2 enrichment. These results suggest that under certain growth conditions, when nutrients are not limiting, ECM fungi respond
rapidly to increasing C-availability through changed biomass production and respiration. 相似文献
978.
Constitutive polymorphic cyanogenesis in the Australian rainforest tree, Ryparosa kurrangii (Achariaceae) 总被引:1,自引:0,他引:1
Cyanogenesis, the liberation of volatile hydrogen cyanide from endogenous cyanide-containing compounds, is a proven plant defence mechanism and the particular cyanogens involved have taxonomic utility. The cyclopentenoncyanhydrin glycoside gynocardin was the only cyanogen isolated from foliar tissue of the rare Australian rainforest tree, Ryparosa kurrangii (Achariaceae). Mechanical damage simulating foliar herbivory did not induce a significant increase in the expression of cyanogenesis over a 24h period, indicating cyanogenic herbivore defence in R. kurrangii is constitutive. The cyanogenic potential of mature leaves was quantitatively polymorphic between trees in a natural population, ranging from 0.54 to 4.77 mg CN g(-1) dry wt leaf tissue. 相似文献
979.
980.