Because they share common precursors and require significant amounts of energy, photosynthesis and defense against herbivores and pathogens may be inversely related. This relationship was examined in Arabidopsis thaliana exposed to herbivory by Trichoplusia ni neonates. The spatial pattern of photosynthesis was compared statistically with that of induction of the defense-related cinnamate-4-hydroxylase (C4H) gene across individual leaves exposed to herbivory in transgenic plants harboring a C4H:GUS gene fusion. In portions of the leaf where C4H:GUS expression was upregulated, photosynthesis was depressed, while non-photochemical quenching was increased, suggesting a trade-off between these two processes. However, photosynthetic damage spread further into surrounding areas than the induction of C4H:GUS expression. Photosynthetic depression was observed up to 1 mm from the edges of holes, whereas C4H:GUS induction typically was limited to about 0.5 mm or less from edges. Other mechanisms may be responsible for the spread of photosynthetic damage beyond where C4H-related defense was induced. Alternatively, C4H induction may reflect a subset of defensive responses more limited in their spatial distribution than the downregulation of photosynthesis. The suppression of photosynthesis in remaining leaf tissue represents a 'hidden cost' of herbivore damage. 相似文献
A new method for hydrolyzing steroid conjugates (both sulfates and glucuronides conjugates) that is efficient, effective, and inexpensive is described. This method comprises incubation of the conjugates--after salting-out into ethyl acetate or elution from a C18 cartridge--with anhydrous methanolic hydrogen chloride (methanolysis) for 10 min. It has been successfully applied to our routine radioimmunoassay screening and GC/MS confirmation studies of steroids in prerace and postrace equine urine samples. Comparative GC/MS studies on entire (male horse) urine samples showed that methanolysis gave amounts of free steroids (estrone, estradiols, testosterone, estrenediols, nandrolone, androstanediols) at least as large as those obtained by solvolysis. Similar studies on urine samples from a gelding that had been administered nandrolone phenylpropionate showed that methanolysis gave larger amounts of free steroids (nandrolone, estranediols) than Helix pomatia enzymatic hydrolysis or solvolysis. Also, TLC studies on methanolysis of corticosteroid conjugates such as hydrocortisone 21-sulfate and hydrocortisone 21-phosphate showed that free corticosteroid was released in 5 min. 相似文献
Trichoderma harzianum is a plant-beneficial fungus that secretes small cysteine-rich proteins that induce plant defense responses; however, the molecular mechanism involved in this induction is largely unknown.Here, we report that the class II hydrophobin Th Hyd1 acts as an elicitor of induced systemic resistance(ISR) in plants. Immunogold labeling and immunofluorescence revealed Th Hyd1 localized on maize(Zea mays) root cell plasma membranes. To identify host plant protein interactors of Hyd1, we screened a maize B73 root c DNA library. Th Hyd1 interacted directly with ubiquilin1-like(UBL). Furthermore, the N-terminal fragment of UBL was primarily responsible for binding with Hyd1 and the eight-cysteine amino acid of Hyd1 participated in the protein-protein interactions. Hyd1 from T. harzianum(Thhyd1) and ubl from maize were co-expressed in Arabidopsis thaliana, they synergistically promoted plant resistance against Botrytis cinerea. RNA-sequencing analysis of global gene expression in maize leaves 24 h after spraying with Curvularia lunata spore suspension showed that Thhyd1-induced systemic resistance was primarily associated with brassinosteroid signaling, likely mediated through BAK1. Jasmonate/ethylene(JA/ET)signaling was also involved to some extent in this response. Our results suggest that the Hyd1-UBL axis might play a key role in inducing systemic resistance as a result of Trichoderma-plant interactions. 相似文献
In this paper, a dual grating structure for unidirectional transmission is presented. The forward and backward transmission performances have been investigated by finite element method. To enhance the forward transmission and to suppress the backward transmission simultaneously, we suggested to cut grooves on the surfaces of one of the gratings, and the effects of the grooves on the optical transmission have been studied. The numerical simulation results reveal that the transmission contrast ratio and the optical unidirectional transmission of the structure can be improved markedly by properly arranging the size and the position of the grooves. The forward transmission can be more than 90%, while the backward transmission transmittance is less than 5%.
The traditional Zn/MnO2 battery has attracted great interest due to its low cost, high safety, high output voltage, and environmental friendliness. However, it remains a big challenge to achieve long‐term stability, mainly owing to the poor reversibility of the cathode reaction. Different from previous studies where the cathode redox reaction of MnO2/MnOOH is in solid state with limited reversibility, here a new aqueous rechargeable Zn/MnO2 flow battery is constructed with dissolution–precipitation reactions in both cathodes (Mn2+/MnO2) and anodes (Zn2+/Zn), which allow mixing of anolyte and catholyte into only one electrolyte and remove the requirement for an ion selective membrane for cost reduction. Impressively, this new battery exhibits a high discharge voltage of ≈1.78 V, good rate capability (10C discharge), and excellent cycling stability (1000 cycles without decay) at the areal capacity ranging from 0.5 to 2 mAh cm‐2. More importantly, this battery can be readily enlarged to a bench scale flow cell of 1.2 Ah with good capacity retention of 89.7% at the 500th cycle, displaying great potential for large‐scale energy storage. 相似文献
A new 9,11‐secosteroid, (22R)‐22‐acetoxy‐3β,6α,11‐trihydroxy‐9,11‐seco‐5α‐cholest‐7‐en‐9‐one, along with twelve known analogues were isolated from the South China Sea gorgonian coral Iciligorgia sp. Their structures were determined by the spectroscopic analysis and comparison with reported data. In an in vitro test of osteoclastic differentiation, three compounds exhibited significant down‐regulating effect whereas two compounds showed significant up‐regulating effect at 0.5 and 1.0 μm . This is the first report of the chemical investigation of the gorgonian Iciligorgia sp. The acetoxy substitution at C‐22 seems to play an important role in the regulating activity. 相似文献
Sequential deposition has great potential to achieve high performance in organic solar cells due to the resulting well‐controlled vertical phase separation. In this work, double bulk heterojunction organic solar cells are fabricated by sequential‐blade cast in ambient conditions. Probed by the in situ grazing incidence X‐ray diffraction and in situ UV–vis absorption measurements, the seq‐blade system exhibits a different tendency from each of the binary films during the film formation process. Due to the extensive aggregation of FOIC, the binary PBDB‐T:FOIC film displays a strong and large phase separation, resulting in low current density (Jsc) and unsatisfactory power conversion efficiency. In the seq‐blade cast system, the bottom layer PBDB‐T:IT‐M produces many crystal nuclei for the top layer PBDB‐T:FOIC, so the PBDB‐T molecules are able to crystallize easily and quickly. Balanced crystallization kinetics between polymer and small molecule and an ideal percolation network in the film are observed. In addition, the balanced crystallization kinetics are favorable toward realizing lower recombination loss through charge transport processes. 相似文献