Effects of dietary nickel on detoxification enzyme activities in the midgut of Spodoptera litura Fabricius larvae

Nickel accumulated in midugt of Spodoptera litura Fabricius could induce the expression of metal-lothionein,one of the most important detoxification proteins in organisms.In the present study,the effects of dietary nickel on the activities of detoxification enzymes,such as carboxylesterase(CarE) and glutathione S-transferase(GST) in the midgut of S.litura larvae have been studied to get an un-derstanding of the detoxification mechanisms of S.litura larvae to excessive nickel.Results showed that CarE activities in the midgut of the 5th instar larvae decreased at lower levels of nickel(≤5 mg/kg),while increased with increasing nickel doses at higher levels of nickel(≥10 mg/kg) exposure in suc-cessive 3 generations.CarE activities of the 6th instar larvae were also characterized as inhibited at low levels of nickel exposure,and improved at higher levels in the 1st generation.CarE activities of 6th instar larvae in the 2nd and 3rd generations were all lower than that in control.However,GST activities in the midgut of the 5th and 6th instar larvae all increased with increasing nickel doses(1―20 mg/kg) in diets.     

Metallothionein expression induced by nickel accumulation in the midgut of Spodoptera litura Fabricius larvae exposed to nickel

Metallothionein expression induced by nickel accumulation in the midgut of Spodoptera litura Fabri- cius larvae was investigated by exposing S. litura larvae to the artificial diets amended with different doses of nickel for 3 generations. Nickel accumulations in the midgut of 6th instar larvae were detected by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and the induced metal- lothionein expression in the midgut of 5th and 6th instar larvae in 120 h were quantified using cad- mium-hemoglobin total saturation methods. The accumulated nickel in the midgut of the 6th instar larvae within a generation increased with the increase of the nickel doses in the treated diets and showed significant dose-dependence with the nickel doses in diets. Metallothioneins induced by nickel accumulated in the larval midgut also increased with nickel doses in diets and with the increasing stressing time in a generation. Results also suggested that the metallothionein expression was differ- ent with the time of S. litura larvae stressed by nickel.     

Ubi1 intron-mediated enhancement of the expression of Bt cry1Ah gene in transgenic maize （Zea mays L.）

The cry1Ah gene was one of novel insecticidal genes cloned from Bacillus thuringiensis isolate BT8. Two plant expression vectors containing cry1Ah gene were constructed. The first intron of maize ubiqutinl gene was inserted between the maize Ubiquitin promoter and cry1Ah gene in one of the plant expressing vectors （pUUOAH）. The two vectors were introduced into maize immature embryonic calli by microprojectile bombardment, and the reproductively plants were acquired. PCR and Southern blot analysis showed that foreign genes had been integrated into maize genome and inherited to the next generation stably. The ELISA assay to T1 and T2 generation plants showed that the expression of CrylAh protein in the construct containing the ubil intron （pUUOAH） was 20% higher than that of the intronless construct （pUOAH）. Bioassay results showed that the transgenic maize harboring cry1Ah gene had high resistance to the Asian corn borers and the insecticidal activity of the transgenic maize containing the ubil intron was higher than that of the intronless construct. These results indicated that the maize ubil intron can enhance the expression of the Bt cry1Ah gene in transgenic maize efficiently     

Asian origin for Polystichum （Dryopteridaceae） based on rbcL sequences

Chloroplast rbcL sequences of 60 species of Polystichum sensu lato (s.l.), including 23 new sequences from southwest China, were used to assess the phylogenetic relationships within the genus. On the basis of estimated evolution rate of rbcL gene and the genetic distance data that passed relative-rate tests, we further estimated the divergence times between some clades of the genus. The phylogenetic relationships were inferred using the neighbor-joining and maximum-parsimony methods, both methods producing trees with completely congruent topology. These trees reveal that all species of Polystichum s.l. in this study (including Cyrtomium and Cyrtomidictyum) form a monophyletic group. The basal split in Polystichum s.l. separates a clade with all Asian members from a clade containing other species from all over the world. The phylogenetic and divergence time estimation results lead us to suggest that Polystichum s.l. originated in Asia in the late Late Cretacous (≈76 Ma) and migrated into other places in the world in early Eocene(≈46 Ma).     

Agrobacterium tumefaciens-mediated Transformation of CryⅠA(b) gene to Trichoderma harzianum

In this study, Cry ⅠA(b) gene was successfully transferred into the biocontrol fungus Trichoderma harzianum with an efficiency of 60-180 transformants per 10^6 spores by using Agrobacterium tumefaciens-mediated transformation. Putative transformants were analyzed to test the presence of Cry ⅠA(b) gene by Southern blot. Most transformants contained a single T-DNA copy. RT-PCR analysis showed that the Cry ⅠA(b) gene was transcribed. Antifungal activities and insecticidal activities of the transformants were examined. There was no obvious difference in antifungal activities between the transformants and their wild strains. The modified mortalities of the transformants T1 and T2 were 69.57% and 91.30%, respectively. The tranformation system mediated by A. tumefaciens proved to be a powerful tool for the filamentous fungi transformation and functional genomic study with its high transformation frequency, simplicity of T-DNA integration, and genetic stability of transformants.     

Deletion analysis of oligomycin PKS genes （olmA） in Streptomyces arermitilis

Gene deletion vector pXL05(pKC1139::△olmA1 △olmA4) was used to disrupt oligomycin PKS encoding genes (olmA ) in Streptomyces avermitilis CZ8-73, the producer of anthelmintic avermectins B and the cell growth inhibitor oligomycin, olmA gene cluster in the chromosome was displaced by deletion allele on the plasmid via double crossover. Four of disruptants were confirmed by Southern blotting. Shaking flask experiments and HPLC analyses showed that the four mutants no longer produced the toxic oligomycin, but only made four components of avermectins B, which were avermectin Bla, Blb, B2a, B2b. The yields of avermectins B in these mutants were separately equal to those in CZ8-73. This revealed that olmA genes deletion did not affect the biosynthesis of avermectins. The deletion mutants were proved to be genetically stable, and thus might be promising strains in industrial production of avermectins B.     

Nickel accumulation and its effects on the survival rate of Spodoptera litura Fabricius under continuous nickel stress

The artificial diets mixed with various concentrations of nickel were offered to the larvae of the phytophagous insect Spodoptera litura Fabricius for 3 generations. Nickel accumulations in the 6th instar larvae, pupae and newly emerged adults of the corresponding generations of S. litura were investigated by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and the effects of nickel accumulations on the survival rate of S. litura were also evaluated by individual rearing. The results showed that nickel accumulated in the 6th instar larvae, pupae and adults of S. litura, and the accu- mulated nickel in all the tested developmental stages within a generation increased with the increase of the nickel doses in the treated diets and showed significant dose-dependent relationship with the nickel doses in the artificial diets. The results also indicated that the nickel accumulations in the 6th instar larvae, pupae, and newly emerged adults from the 3rd generation were higher than those from the 2nd generation, which were also higher than those from the 1st generation. Nickel concentrations in pupae and adults were significantly lower than those in larvae, which indicated that the excessive nickel might be excreted during metamorphosis. Furthermore, larval survival rate, pupation rate and eclosion rate of S. litura in the tested three generations all decreased with the increase of the nickel doses in the treated diets.     

Effects of dietary nickel on apoptosis of hemocytes of Spodoptera litura (Fabricius) larvae

Effects of dietary nickel on apoptosis of hemocytes of the 6th instar larvae of Spodoptera litura Fabricius were evaluated using flow cytometry and Laser Scanning Confocal Microscopy (LSCM) by feeding S. litura larvae with artificial diets amended with different concentrations of nickel (1, 5, 10, 20 and 40 mg/kg) for 3 generations. Results showed that the hemocyte apoptosis rate of the 1st generation larvae increased with the increasing nickel concentrations in diet, and the apoptosis rate in the treatment with 40 mg/kg nickel was significantly higher than that in other treatments. In the 2nd generation, the highest hemocytes apoptosis rate was recorded in the treatment of the larvae exposed to 5 mg/kg nickel. The apoptosis rates in the larvae stressed by higher concentrations of nickel were lower than that in control. The apoptosis rates in the larvae exposed to nickel for 3 generations showed similar concentration-responses with that in the 2nd generation. However, the apoptosis rates in the larvae stressed with higher levels of nickel were all significantly inhibited in comparison with that in control. Therefore, effects of nickel stress on apoptosis of S. litura larvae were related with the nickel concentration in diets and the larval generations that were stressed by nickel.     

Southern rice black-streaked dwarf virus: A new proposed <Emphasis Type="Italic">Fijivirus</Emphasis> species in the family <Emphasis Type="Italic">Reoviridae</Emphasis>

For the past several years, a novel dwarf disease has been observed on rice （Oryza sativa） in some regions of Guangdong Province and Hainan Province, southern China. Infected plants showed stunting, dark leaf and small enations on stem and leaf back. Typical Fijivirus viroplasma containing crystalline arrayed spherical virons approximately 70--75 nm in diameter and tubular structures were detected in ultrathin sections by an electron microscope in parenchyma phloem cells of the infected plants. The virus was transmitted to rice seedlings by white-backed planthoppers, Sogatella furcifera （Hemiptera： Delphacidae）, collected in the diseased fields. Analysis of dsRNA extracts from infected plants revealed ten linear segments, which were similar to the electrophoretic profile of Rice black-streaked dwarf virus （RBSDV）. RT-PCR with a single primer which matched to a linker sequence ligated to both 3＇ ends of the viral genomic dsRNAs resulted in amplification of genome segments 9 （S9） and 10 （S10） cDNA products. The complete nucleotide sequences of S9 and S10 were obtained from clones of the RT-PCR amplicon exhibited characteristic properties of Fijivirus including low GC content （34.5% and 35.6%）, genus conserved 5＇ and 3＇ termini sequences and similar genome organization. Blast searches indicated that the sequences of S9 and S10 shared 68.8%--74.9% and 67.1% --77.4% nucleotide identities with those of viruses in the Fijivirus group 2, respectively. These values were similar to those among other viruses in the Fijivirus group 2 and considerably lower than those among RBSDV isolates. Phylogenetic trees based on S9 and S10 nucleotide sequences and their putative amino acid sequences showed that this virus represented a separate branch among other Fijiviruses. The virus was also detected by a nested RT-PCR assay in corn （Zea mays）, barnyard grass （Echinochloa crusgalll）, Juncellus serotinus and flaccidgrass （Pennisetum flaccidum） in and/or adjacent to the infected rice fields. I     

Reporter-based screen for <Emphasis Type="Italic">Arabidopsis</Emphasis> mutants compromised in nonhost resistance

Plants are exposed to many potentially pathogenic microbes in the environment, but each species is only susceptible to a limited number of pathogens. The broad resistance is referred to as nonhost resistance. To date, little is known about the underlying mechanism of nonhost resistance and the signaling transduction process. Here we describe a simple method for isolating Arabidopsis nonhost resistance mutants against a nonadapted bacterial pathogen. A RAP2.6 promoter-driven LUC reporter system was developed to replace the tedious bacterial growth assay during the primary screening. The RAP2.6-LUC reporter gene is normally induced by the virulent bacterium Pseudomonas syringae pv tomato but not the nonadapted bacterium P. syringae pv phaseolicola. By using this method we iso- lated 4 mutants displaying strong reporter activity in response to P. syringae pv phaseolicola, which were characterized in some details, ebsl, ebs2, ebs3, and ebs4 （enhanced bacterial susceptibility） were compromised in resistance against P. syringae pv phaseolicola and/or P. syringae pv tomato. In addition, ebs4 showed enhanced hypersensitive response to the incompatible bacterium P. syringae pv tomato （avrB）. These results demonstrated that the method is suited for large scale screening for nonhost resistance mutants.     

Photodegradation of <Emphasis Type="Italic">N</Emphasis>-nitrosodiethylamine in water with UV irradiation

The direct photolysis of N-nitrosodiethylamine （NDEA） in water with ultraviolet （UV） irradiation was investigated. Results showed that NDEA could be completely degraded under the direct UV irradiation. The effects of the experimental conditions, including the initial concentration of NDEA, humic acid and solution pH, were studied. The degradation products of NDEA were identified and quantified with gas chromatography-mass spectrometry （GC-MS） and high performance liquid chromatography （HPLC）. It was confirmed that methylamine （MA）, dimethylamine （DMA）, ethylamine （EA）, diethylamine （DEA）, NO2^- and NO3^- were the main degradation products. The photolysis degradation mechanism of NDEA was also discussed. As a result of N-N bond fission, NDEA was degraded by direct UV irradiation.     

Double-Talk Detection Algorithm Based on the Ι2 Norm

Echo canceller generally needs a double-talk detector which is used to keep the adaptive filter from diverging in the appearance of near-end speech. In this paper we adopt a new double-talk detection algorithm based on ι2 norm to detect the existence of near-end speech in an acoustic echo canceller. We analyze this algorithm from the point of view of functional analysis and point out that the proposed double-talk detection algorithm has the same performance as the classic one in a finite Banach space. The remarkable feature of this algorithm is its higher accuracy and better computation complexity. The fine properties of this algorithm are confirmed by computer simulation and the application in a multimedia communication system.     

Landscape ecological evaluation on the artificial forest of <Emphasis Type="Italic">Leucaena leucocephala</Emphasis>

Based on the theory of ecology, this article conducted a landscape ecological evaluation on Leucaena leucocephala artificial forest in the add-hot valley, Yuanmou Xiaokua hill, using a combination method of qualitative analysis and landscape comprehensive evaluation. The comprehensive evaluation indexes of landscape include forest coverage, biodiversity, stability, soil erosion, environmental quality, availability, scientific research characteristic, economic benefits. Using AHP （analytical hierarchy process）, determine the grade of ecological evaluation factors and the weight of evaluation index and calculate the CEI （comprehensive evaluation index） on ecological evaluation. Evaluation results showed that the area CEI was 0.714 225, a better quality of the ecological level, but biodiversity indicators was the lowest. To sum up, it was difficult to maintain ecological restoration effectiveness and process but also guarantee a good biodiversity in the add-hot valleys. We must reasonably arrange the alien species and the native species, in order to obtain a stable and sustainable eco-system.     

Direct observation of monomer film structure of bacteriochlorophyll <Emphasis Type="Italic">c</Emphasis>

The adsorption and assembling of bacteriochlorophyll c (BChl c) on a highly oriented pyrolytic graphite (HOPG) surface have been investigated by the scanning tunneling microscopy (STM). BChl c molecules are found to self-organize a well-defined adlayer on HOPG surface with a monomeric structure different from the dimer association seen on adlayers of Chls a, c and BChlide c, d. A structural model is proposed for the adlayer.     

Seasonal variation of gut Cyanophyta contents and liver GST expression of mud carp （Cirrhina molitorella） and Nile tilapia （Oreochromis niloticus） in the tropical Xiangang Reservoir （Huizhou, China）

Liver glutathione S-transferase(GST) plays a major role in the detoxification of microcystins(MCs) via conjugation to glutathione(GSH).We evaluated the relationship between seasonal variation in fish gut contents and the expression of GST isoforms in mud carp(Cirrhina molitorella) and Nile tilapia(Oreochromis niloticus).We quantified the abundance and diversity of plankton in the water column and foregut of mud carp and Nile tilapia in the tropical Xiangang Reservoir between October 2007 and July 2008.The mRNA expression of 7 liver GST isoforms was determined by real-time RT-PCR.The gut contents of both species were dependent on the amount and type of phytoplankton and zooplankton in the water.The expression of liver GST genes in Nile tilapia and mud carp was positively and negatively correlated,respectively,with the abundance of toxic cyanobacteria in the fore-gut.The expression of liver GST mRNA was correlated to the abundance of toxic cyanobacteria in the gut contents of both species,suggesting that mRNA expression of GST isoforms could be used as a biomarker in Nile tilapia and mud carp to monitor cyanobacteria blooms in reservoirs.     

Cloning and Characterization of the fecC Gene Necessary for Optimal Growth under Iron-Deficiency Conditions in the Cyanobacterium Anabaena sp. PCC 7120

The fecC gene encoding a putative iron (Ⅲ) dicitrate transporte rwas cloned from nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO3^- , NH1^- or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wildtype strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that the fecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed that fecC gene product is required for optimal growth under iron-deficient conditions in Anabaena sp. PCC 7120.     

Male panda （Ailuropoda melanoleuca） urine contains kinship information

Chemical communication plays an important role in kin selection and mate choice in mammals. The covariance of odor-genes of rodents has been documented and kinship odor has been proposed and termed, yet little is known of the relationship between genetic relatedness and chemical composition of kinship odors. Giant pandas （Ailuropoda melanoleuca） rely substantially on chemical communication to mediate their social interactions. To examine the relationship between genetic relatedness and compounds in the urine/anogenital gland secretions, we compared the similarities between genetic relatedness and the chemical profiles of anogenital gland secretions and urine via lineage construction and GC-MS （gas chromatography and mass spectrometry）. We found that information about kinship odors was present only in the urine of male adults in the mating season but absent in the non-mating season. Adult females and all sub-adults did not have such kinship odors in either mating or non-mating season. Therefore, kinship odor in the panda was contingent on age, sex, and season. This is the first report about the condition-dependent expression of kinship odor, which may have a significant implication in the practice of panda conservation in relation to chemical communication and sexual selection.     

Characterizations of <Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>(<Emphasis Type="Italic">R</Emphasis>) using tight wavelet frames

In this paper,a Littlewood-Paley function characterization of the spaces L p(R),1相似文献   

Temperature-sensitive gold-nanotube array membranes modified with poly（N-isopropylacrylamide）

A kind of temperature-sensitive nanotube array membrane was developed by modifying gold-nanotube array membranes with poly（N-isopropylacrylamide） （PNIPAm）. The permeation ability of the mem-branes at different temperatures was investigated using sodium fluorescein and quantum dots as probes. The results showed that the pore diameter of nanotube was changed due to the reversible response of PNIPAm-modified membranes to temperature, and then the permeation ability of the mem-branes was changed. The permeation of fluorescence probes was slow and even almost blocked at 25℃ （below the lower critical solution temperature, LCST）, since PNIPAm formed expanded structures and decreased the pore size. While at 40℃ （above the LCST）, the permeation was increased, since PNIPAm became compact structures and the pore diameter was increased. Furthermore, the permeation ability of the temperature-sensitive nanotube array membranes could be adjusted reversibly and it is possible to use the membranes in nanofluidic devices, nanogates, etc.