摘要：
Phytolacca americana (pokeweed) has been found to be a new manganese hyperaccumulator plant by means of field surveys on Mn-rich soils and by Hydroponics experiments. This species not only has remarkable tolerance to Mn but also has extraordinary uptake and accumulation capacity for this element. The maximum Mn concentration in the leaf dry matter was 8000 mg/g on Xiangtan Mn tailings wastelands, with a mean of 6490 mg/kg. The species was characterized by a high translocation factor (>10.76). Under nutrient solution culture conditions, manganese concentration in the shoots increased with increasing external Mn levels. The maximum concentration of Mn in leaves reached 47.06 g/kg at 50 mmol/L Mn. This species provides a new plant resource for exploring the mechanism of Mn hyperaccumulation and has potential for use in the phytoremediation of Mn contaminated soils.
摘要：
The Duffing equation with even-odd asymmetrical nonlinear-restoring force and one external forcing is investigated. The conditions of existence of primary resonance, second-order, third-order subharmonics, morder subharmonics and chaos are given by using the second-averaging method, the Melnikov method and bifurcation theory. Numerical simulations including bifurcation diagram, bifurcation surfaces and phase portraits show the consistence with the theoretical analysis. The numerical results also exhibit new dynamical behaviors including onset of chaos, chaos suddenly disappearing to periodic orbit, cascades of inverse period-doubling bifurcations, period-doubling bifurcation, symmetry period-doubling bifurcations of period-3 orbit, symmetrybreaking of periodic orbits, interleaving occurrence of chaotic behaviors and period-one orbit, a great abundance of periodic windows in transient chaotic regions with interior crises and boundary crisis and varied chaotic attractors. Our results show that many dynamical behaviors are strictly departure from the behaviors of the Duffing equation with odd-nonlinear restoring force.
摘要：
Autooxidation of five polyphenols representing range of different hydrophobicities (catechin gallate (CG), (-) catechin((-)C), epicatechin (EC), epigallocatechin gallate (EGCG) and epigallocatechin (EGC)) in three different aqueous solutions: molecular solution, micellar solution (Tween-20) and liposomal dispersion (soybean lecithin) was monitored by HPLC. The rate of oxidation of the five polyphenols was higher at pH 4.5 than at pH 3.5. Compared with the control, addition of Tween-20 (micellar structure) and lecithin (liposomal structure) significantly decreased the degradation of polyphenols. In the presence of lecithin the autooxidation of all the five polyphenols was slower than in the presence of Tween-20. The effective protection of the colloidal structures was compared with the hydrophobicity of the polyphenols estimated from the partitioning between octanol and water. The protection from oxidation in the presence of the colloidal structures (micellar or liposomal) increased with increasing partitioning of a polyphenol towards the hydrophobic environment. The protecting effect of the colloidal structures was more effective at pH 4.5 than at pH 3.5.
摘要：
The piezoelectric bulk acoustic wave (BAW) impedance analysis method was employed to monitor in situ the proteinase-catalyzed hydrolyzation of casein and the effect of pesticide D-allethrin on the proteinase activity in the midgut of the spider Pardosa pseudoannulata, and the results obtained were verified by ultraviolet spectroscopy. The hydrolyzation was significantly increased in the presence of low-dose D-allethrin, whereas significantly inhibited in the presence of high-dose D-allethrin, and a correlation was found precisely between the enzyme activity reflected by the final frequency shift after the hydrolyzation and the concentration of D-allethrin, with a significant frequency response observed even at a 1.5 × 10-5 volume ratio of D-allethrin to distilled water. The present work may have presented a novel method feasible for study on the mechanism of excitability of spiders under low-dose D-allethrin pesticide and quick detection of proteinase activity.
期刊：
Pesticide Biochemistry and Physiology,2007年89(2):146-150 ISSN：0048-3575
通讯作者：
Qiu, Xinghui
作者机构：
[Qiu, Xinghui] Chinese Acad Sci, Inst Zool, State Key Lab Integrated Management Pest Insects, Beijing 100101, Peoples R China.;Hunan Agr Univ, Anim Med Coll, Changsha 410128, Peoples R China.
通讯机构：
[Qiu, Xinghui] C;Chinese Acad Sci, Inst Zool, State Key Lab Integrated Management Pest Insects, Beijing 100101, Peoples R China.
摘要：
We investigated the molecular basis of resistance in a strain of house fly (BJD) from Beijing, China. This strain showed 567-fold resistance to commonly used deltamethrin. Flies were 64-fold resistant to deltamethrin synergized by piperonyl butoxide (PBO). The 5'-flanking sequence of the cytochrome P450 gene CYP6D1 in BJD strain had a 15-bp insert as in the LPR strain. Two mutations (kdr, super-kdr) in the voltage sensitive sodium channel (VSSC) were also detected in the BJD strain. Our results showed that a combination of resistance alleles for CYP6D1 and VSSC existed in deltamethrin resistant house flies in China. (C) 2007 Elsevier Inc. All rights reserved.
期刊：
JOURNAL OF PLANKTON RESEARCH,2007年29(9):739-745 ISSN：0142-7873
通讯作者：
Jin, XC
通讯机构：
[Jin, XC ] ;Chinese Res Acad Environm Sci Craes, Res Ctr Lake Ecol & Environm, State Environm Protect Key Lab Lake Pollut Contro, Beijing 100012, Peoples R China.
摘要：
The dominance of gas-vacuolate cyanobacteria is often attributed to their buoyancy and to their ability to regulate buoyancy in response to environmental conditions. Changes in absolute gas vesicles volume, carbohydrate content, protein content and colony buoyancy of Microcystis flos-aquae were investigated during nitrogen-limited, phosphorus-limited and nutrient-replete growth. When nutrient-replete, M. flos-aquae cells consistently had excess gas vesicles, which provided sufficient buoyancy that the influence of daily carbohydrate changes on cells upon floatation was negligible. However, during nitrogen-limited growth, gas vesicle volume per cell decreased significantly with nitrogen exhaustion. The maximum decrease of gas vesicle volume was up to 84–88%. At the same time, cellular carbohydrate content had an accumulation trend. The decrease of gas vesicle buoyancy together with the daily increase in carbohydrate are suggested to explain the daily changes in the cell floatation. During phosphorus-limited growth, gas vesicle volume per cell decreased slightly (maximum to 22–32%), and they still provided sufficient buoyancy that most cells kept floating even though there were significant daily carbohydrate changes. Since nitrogen limitation caused more significant buoyancy loss than phosphorus limitation did, surface water blooms may disappear or appear frequently in nitrogen limited water bodies while they may persist a longer time in phosphorus limited water bodies. The quantitative analysis in buoyancy change by gas vesicles, carbohydrate and protein suggested that long-term buoyancy regulation was mainly determined by changes of gas vesicle volume whereas short-term buoyancy regulation was mainly determined by carbohydrate accumulation and consumption. Both long-term and short-term buoyancy regulation were influenced by cell nutrient status. Furthermore, gas vesicle volume per cell and protein content changed in the same way in both nitrogen-limited and phosphorus-limited growth, which implied that the decrease of gas vesicles were associated with controls of total protein synthesis.
摘要：
Cucumber mosaic virus (CMV) and zucchini yellow mosaic virus (ZYMV) are two principal viruses infecting cucurbitaceous crops, and their synergy has been repeatedly observed. In our present work, a real-time reverse transcription-polymerase chain reaction procedure was established to study the accumulation kinetics of these two viruses in single and combined infections at the molecular level. The accumulations of open reading frames (ORFs) for 1a, 2a, 3a and coat protein (CP) of CMV and CP of ZYMV were tested. In the single infection, CMV-Fny ORFs accumulated to their maxima in cucumber or bottle gourd at 14 d post-inoculation (dpi), and gradually declined thereafter. ZYMV-SD CP ORF reached maximal accumulation at 14 d post-inoculation (dpi), and gradually declined thereafter. ZYMV-SD CP ORF reached maximal accumulation at 14 and 28 dpi on cucumber and bottle gourd, respectively. However, when coinfected with CMV-Fny and ZYMV-SD, the maximal accumulation levels of all viral ORFs were delayed. CMV-Fny ORFs reached their maxima at 21 dpi on both hosts, and ZYMV-SD CP ORF reached maximal accumulation at 21 and 28 dpi on cucumber and bottle gourd, respectively. Generally, the accumulation levels of CMV-Fny ORFs in the co-infection were higher than those in the single infection, whereas the accumulation of ZYMV-SD CP ORF showed a reverse result.
作者机构：
[Chen, Li-yun; Xiao, Ying-hui; Tang, Wen-bang; Lei, Dong-yang] Hunan Agr Univ, Rice Res Inst, Changsha 410128, Peoples R China.
通讯机构：
[Chen, LY ] ;Hunan Agr Univ, Rice Res Inst, Changsha 410128, Peoples R China.
关键词：
super hybrid rice;breeding strategy;super parent;hybrid rice seed;production
摘要：
The great progress in super rice breeding both in China and other countries has been made in recent years. However, there were three main problems in super rice breeding: 1) the super rice varieties were still rare; 2) most super rice varieties exhibited narrow adaptability; and 3) current breeding theories emphasized too much on the rice growth model, but they were unpractical in guidance for rice breeding. According to the authors' experience on the rice breeding, the breeding strategies including three steps (super parent breeding, super hybrid rice breeding and super hybrid rice seed production) were proposed, and the objectives of each step and the key technologies to achieve the goals were elucidated in detail. The super parent of hybrid rice should exhibit excellent performance in all agronomic traits, with the yield or sink capacity reached the level of the hybrid rice control in regional trials. The super hybrid rice combination should meet the following criteria: good rice quality, wide adaptation, lodging resistance, resistance to main insects and diseases, and the yield exceeded above 8% over the control varieties in the national and provincial regional trials. To achieve the goal, the technical strategies, such as selecting optimal combination of the parents, increasing selection pressure, paying more attention to harmony of ideal plant type, excellent physiological traits and all the agronomic traits, should be emphasized. The yield of seed production should reach 3.75 t/ha and 5.25 t/ha for the super hybrid rice combinations derived from early-season and middle-season types of male sterile lines, respectively. The main technologies for raising seed production yield included selecting optimum seed production site, using the male sterile line with large sink capacity and good outcrossing characteristics, and improving the amount of the pollen by intensive cultivation of the male parent. According to the technologies of the three-step breeding on super hybrid rice, two super rice parents, including a male parent 996 and a thermo(photo)-genic male sterile [T(P) GMS] line C815S, were bred. Furthermore, a super early hybrid rice combination, Luliangyou 996, which could be used as a double-season early rice variety in middle and lower reaches of the Yangtze River, China, was bred by using the super rice variety 996 as the male parent, and several hybrid rice combinations with higher yield than control variety in regional trials both of Hunan Province and state were bred with the T(P) GMS line C815S as the female parent.
摘要：
Evolution of resistance by pests is the greatest threat to the continuous success of the Bacillus thuringiensis (Bt) toxins used in conventional sprays or in transgenic plants. The most common mechanism of insect resistance to Bt is reduced binding of toxins to target sites in the brush border membrane of the larval mid-gut. In this paper, binding experiments were performed with three I-125-Cry1A toxins and the brush border membrane vesicles from Cry1Ac resistant or susceptible strains of Helicoverpa armigera. The homologous competition test showed that there was no significant difference in Cry1Ac-binding affinity, but the concentration of Cry1Ac-binding sites dramatically decreased in the resistant strain (R-t decreased from 5.87 +/- 1.40 to 2.23 +/- 0.80). The heterologous competition test showed that there were three Cry1Ac-binding sites in the susceptible strain. Among them, site I bound with all three Cry1A toxins, site 2 bound with both Cry1Ab and Cry1Ac, and site 3 only bound with Cry1Ac. In the Cry1Ac resistant strain, the binding capability of site 1 with Cry1Ab decreased and site 2 did not bind with Cry1Ac. It is suggested that the absence of one binding site is responsible for H. armigera resistance to Cry1Ac. This result also showed that the resistance fitted the "mode 1" pattern of Bt resistance described previously. (c) 2005 Elsevier Inc. All rights reserved.
摘要：
In this paper, we consider the n-order neutral delay differential equation with unstable type ((x(t) - p(t)x(t - tau))((n)) = q(t)vertical bar x(t - sigma)vertical bar(alpha-1)x(t - sigma), t >= t(0), where n >= 2 is an even integer, alpha >= 1, tau > 0, sigma > 0 and p, q is an element of C([t(0), +infinity], R+). We first prove that this equation always has an unbounded positive solution, then some new bounded oscillation and nonoscillation criteria are obtained. (c) 2005 Elsevier Inc. All rights reserved.
