Age-related Metabolic Effects of Acetaldehyde on Rats With Reference to Detoxification Enzymes and Sulfhydryl Groups

Induced-acetaldehyde toxic effects on gluatathione [GSH] metabolism and sulfhydryl (SH) groups in liver and in brain of female albino rats with reference to age was studied.The total -SH groups were decreased whereas the specific activities of glutathione-S-transferase [GST] and glutathione peroxidase [GP0] were increased in acetaldehyde treated rats. However, the specific activity levels of glutathione reductase [GR] and Γ-glutamylcysteine synthetase [Γ-GCS] were decreased. In general, acetaldehyde indueed changes in the specific activities of the enzymes that increase with increasing age

Effect of jasmonate treatments on leaves of Rosa rugosa‘Plena’and detoxification enzymes and feeding of adult Monolepta hieroglyphica

To study the effect of jasmonates(JAs)on the resistance of economic forest plants to insects,R osa rugosa‘Plena'leaves were treated with 1 mmol/L jasmonic acid(JA),methyl jasmonate(MeJA)and Z-jasmone,then the content of tannin and total phenol in leaves and the feeding area of Monolepta hieroglyphica adults on leaves were measured.Changes in the activities of detoxification enzymes in adult M.hieroglyphica that had fed on leaves treated with JAs were also studied.Tannin and total phenol levels in leaves increased significantly after treatment with JAs,and tannin level was 1.36–1.55-fold higher than in the control after treatment with 1 mmol/L MeJA.The total content of phenol in leaves treated with 1.0 mmol/L Z-jasmone increased by 1.33–2.20-fold compared with those of the control.The activities of detoxification enzymes in adults were inhibited to differing degrees:activity of alkaline phosphatase(AKP)first increased,then decreased;the activities of acid phosphatase(ACP),glutathione S-transferases(GSTs)and carboxylesterase(CarE)following treatment with 1 mmol/L MeJA were significantly reduced and were 22%–31%,11%–26%,and 11%–31%lower than those of the control,respectively.Moreover,the feeding area of adult M.hieroglyphica on the leaves treated with JAs was significantly reduced(P<0.05).The feeding area of economic forest R.rugosa‘Plena'leaves treated with 1 mmol/L MeJA decreased by 17%–43%compared with that of the control.Moreover,the decrease in the adult M.hieroglyphica feeding area was highly positively correlated with the content of tannin and positively correlated with the contents of total phenol of economic forest R.rugosa‘Plena'leaves.The reduced feeding area of adult M.hieroglyphica was highly negatively correlated with the activities of AKP and ACP and negatively correlated with those of the GSTs.In conclusion,the use of 1 mmol/L MeJA can noticeably decrease the deleterious effects of adult M.hieroglyphica.

Effect of heat shock on the susceptibility of Frankliniella occidentalis(Thysanoptera：Thripidae) to insecticides

Currently, insecticides are considered as the primary approach for controlling western flower thrips, Frankliniella occidentalis（Pergande）（Thysanoptera： Thripidae）. However, the heavy use of insecticides resulted in high insect resistance and serious environmental pollution. Given its characteristics of ease of operation and environmental friendliness, insect control using high temperature is receiving considerable renewed research interest. However, although the combination of insecticides and high temperature to control F. occidentalis has been studied before, few studies have focused on the short-term effect of such treatment. In a laboratory study, F. occidentalis adults and second-instar nymphs were exposed to 45℃ for 2 h. Then, their susceptibility to acetamiprid, spinosad, methomyl, and beta-cypermethrin was tested after different periods of recovery time（2–36 h）. Additionally, the specific activity of three detoxification enzymes（esterase, glutathione S-transferase, and cytochrome p450（CYP） monooxygenase） of the treated insects was determined. The results indicated that the fluctuation of susceptibility to insecticides and detoxification enzyme activity during F. occidentalis recovery from heat shock are related. Furthermore, several recovery time points（2, 30, and 36 h） of significant susceptibility to four tested insecticides compared with the control were found during the treatment of adults that were heat-shocked. Recovery time points of higher susceptibility compared with the control depended on different insecticides during the second-instar nymph recovery from heat shock. Interestingly, the fluctuation of CYP monooxygenase activity exhibited a trend that was similar to the fluctuation of susceptibility to insecticides（especially spinosad） during the recovery from heat shock of adults. In addition, the glutathione S-transferase and CYP monooxygenase activity trend was similar to the trend of susceptibility to spinosad during the recovery from heat shock of second-instar nymphs. Our results provide a new approach for controlling F. occidentalis using the combined heat shock and insecticide. This effectively enhances the control efficiency of heat shock and significantly reduces the application of insecticides.

Deoxynivalenol accumulation and detoxification in cereals and its potential role in wheat-Fusarium graminearum interactions

Deoxynivalenol(DON)is a prominent mycotoxin showing significant accumulation in cereal plants during infection by the phytopathogen Fusarium graminearum.It is a virulence factor that is important in the spread of F.graminearum within cereal heads,and it causes serious yield losses and significant contamination of cereal grains.In recent decades,genetic and genomic studies have facilitated the characterization of the molecular pathways of DON biosynthesis in F.graminearum and the environmental factors that influence DON accumulation.In addition,diverse scab resistance traits related to the repression of DON accumulation in plants have been identified,and experimental studies of wheat–pathogen interactions have contributed to understanding detoxification mechanisms in host plants.The present review illustrates and summarizes the molecular networks of DON mycotoxin production in F.graminearum and the methods of DON detoxification in plants based on the current literature,which provides molecular targets for crop improvement programs.This review also comprehensively discusses recent advances and challenges related to genetic engineering-mediated cultivar improvements to strengthen scab resistance.Furthermore,ongoing advancements in genetic engineering will enable the application of these molecular targets to develop more scab-resistant wheat cultivars with DON detoxification traits.

Chemopreventive Potential of Canola Leafy Greens and Other Cruciferous Vegetables on Azoxymethane (AOM)-Induced Colon Cancer in Fisher-344 Male Rats

Cruciferous vegetables have great health benefits, and their components may be significant in the inhibition of colon tumors. The objective of this study was to investigate and compare the chemopreventive potential of cabbage, turnip greens, collard greens and canola greens on azoxymethane (AOM)-induced colon cancer. Following a one-week acclimatization period, forty-two Fisher-344 male rats were randomly assigned to five groups (treatment groups: n = 8;control: n = 10). Four groups were fed treatment diets consisting of the selected cruciferous vegetables at 5%, while the C group was fed AIN-93 growth diet. Colon tumors were induced by administration of AOM at 7 and 8 weeks of age and rats were killed by CO2 asphyxiation at 45 weeks of age. Results show a 42.85% tumors incidence in rats fed canola greens compared to 100% in the rats fed cabbage and the control. Rats fed control had higher tumors/ tumor bearing rat (TBR) ratio (4.5) compared to those seen in treatment groups (1 - 1.71). Significant differences (P ≤ 0.05) were noted in weight gain, cecal wall weight and total cecal weight in the control compared to treatment groups. Hepatic catalase (CAT) and Glutathione-S-Transferase (GST) activities (43.05 and 2.02 μmol/mg, respectively) in rats fed canola were significantly higher (P ≤ 0.05) compared to the control (10.22 and 0.58 μmol/mg) and other treatment groups. Superoxide dismutase (SOD) activity (μmol/mg) in rats fed canola (0.29), cabbage (0.26) and turnip greens (0.25) were similar, however, significantly higher (P ≤ 0.05) compared to the control (0.09). Activities of glutathione peroxidase (GPX) increased in the order: collard greens > canola greens > turnip greens > cabbage > control. Selected cruciferous vegetables, including canola leafy greens, were effective in reducing incidence of AOM-induced colon tumors in Fisher-344 male rats and may be useful as dietary chemopreventive agents.

The dynamic changes of genes revealed that persistently overexpressed genes drive the evolution of cyflumetofen resistance in Tetranychus cinnabarinus

Changes in gene expression are associated with the evolution of pesticide resis-tance in arthropods.In this study,transcriptome sequencing was performed in 3 different resistance levels(low,L;medium,M;and high,H)of cyflumetofen-resistant strain(YN-CyR).A total of 1685 genes,including 97 detoxification enzyme genes,were upregulated in all 3 stages,of which 192 genes,including 11 detoxification enzyme genes,showed a continuous increase in expression level with resistance development(L to H).RNA in-terference experiments showed that overexpression of 7 genes(CYP392A1,TcGSTd05,CCE06,CYP389A1,TcGSTz01,CCE59,and CYP389C2)is involved in the development of cyflumetofen resistance in Tetranychus cinnabarinus.The recombinant CYP392A1 can effectively metabolize cyflumetofen,while CCE06 can bind and sequester cyflumetofen in vitro.We compared 2 methods for rapid screening of resistance molecular markers,in-cluding short-term induction and 1-time high-dose selection.Two detoxification enzyme genes were upregulated in the field susceptible strain(YN-S)by induction with 20%lethal concentration(LC2o)of cyflumetofen.However,16 detoxification enzyme genes were up-regulated by 1-time selection with LCso of cyflumetofen.Interestingly,the 16 genes were overexpressed in all 3 resistance stages.These results indicated that 1685 genes that were upregulated at the L stage constituted the basis of cyflumetofen resistance,of which 192 genes in which upregulation continued to increase were the main driving force for the de-velopment of resistance.Moreover,the 1-time high-dose selection is an efficient way to rapidly obtain the resistance-related genes that can aid in the development of resistance markers and resistance management in mites.

Genomic resources for the brown planthopper, Nilaparvata lugens： Transcriptome pyrosequencing and microarray design

The brown planthopper, Nilaparvata lugens is a pest of cultivated rice through- out Asia and is controlled using insecticides and/or resistant rice varieties. This species has developed resistance to many classes of insecticide and biotypes have developed that are vir- ulent against formerly resistant rice cultivars. Insects use a suite of detoxification enzymes, including cytochrome P450s, glutathione S-transferases and carboxyl/cholinesterases to defend themselves against plant secondary metabolites and pesticides. Pyrosequencing on the Roche 454-FLX platform was used to produce a substantial expressed sequence tag （EST） dataset to complement the existing Sanger sequenced ESTs in GenBank. A total of 78 959 reads were combined with the 37 392 publically available Sanger ESTs; these assembled into 8 911 contigs and 10 620 singletons. Analysis of the distribution of tenta- tive unique genes （TUGs） with the gene ontology for biological processes and molecular functions suggests that the 454 and Sanger EST assembly is broadly representative of the N. lugens transcriptome. The brown planthopper transcriptome was found to contain 31 TUGs encoding P450s, nine encoding glutathione S-transferases and 26 encoding car- boxyl/cholinesterases and many of these are putatively involved in the detoxification of xenobiotics. The Agilent eArray platform was used to construct an oligonucleotide mi- croarray populated with probes for ~ 19 000 unigene sequences, including all those known to encode detoxification enzymes. The genomic resources developed in this study will be useful to the community studying this crop pest and will help elucidate the molecular mechanism underlying insecticide resistance and planthopper adaptation to resistant rice cultivars.

Effects of chlorpyrifos on enzymatic systems of Cydia pomonella （Lepidoptera： Tortricidae） adults

The control program of codling moth （Cydia pomonella L.） in the Rio Negro and Neuqu6n Valley is intended to neonate larvae. However, adults may be subjected to sublethal pesticide concentrations generating stress which might enhance both mutation rates and activity of the detoxification system. This study assessed the exposure effects of chlorpyrifos on target enzyme and, both detoxifying and antioxidant systems of surviving adults from both a laboratory susceptible strain （LSS） and a field population （FP）. The results showed that the FP was as susceptible to chlorpyrifos as the LSS and, both exhibited a similar chlorpyrifos-inhibitory concentration 50 （IC50） of acetylcholinesterase （ACHE）. The FP displayed higher carboxylesterase （CarE） and 7-ethoxycoumarine O-deethylase （ECOD） activities than LSS. Both LSS and FP showed an increase on CarE activity after the exposure to low-chlorpyrifos concentrations, followed by enzyme inhibition at higher concentrations. There were no significant differences neither in the activities of glutathione S-transferases （GST）, catalase （CAT） and superoxide dismutase （SOD） nor in the reduced glutathione （GSH） content between LSS and FP. Moreover, these enzymes were unaffected by chlorpyrifos. In conclusion, control adults from the FP exhibited higher CarE and ECOD activities than control adults from the LSS. AChE and CarE activities were the most affected by chlorpyrifos. Control strategies used for C. pomonella, such as rotations of insecticides with different modes of action, will probably delay the evolution of insecticide resistance in FPs from the study area.

Frequencies and mechanisms of pesticide resistance in Tetranychus urticae field populations in China

The two-spotted spider mite Tetranychus urticate is an important agricultural pest worldwide.It is extremely polyphagous and has developed resistance to many pesticides.Here,we assessed the pesticide resistance of seven field populations of T.urticae in China,their target site mutations and the activities of their detoxification enzymes.The results showed that abamectin and the traditional pesticides pyridaben,profenofos and bifenthrin had higher resistance or lower toxicity than more recently developed pesticides including chlorfenapyr,spinetoram,cyflumetofen,cyenopyrafen,bifenazate and B-azolemiteacrylic.The frequency of point mutations related to abamectin resistance,G314D in the glutamate-gated chloride channel 1(GluCl1)and G326E in GluC13,ranged 47%-70%and 0%-97%,respectively.The frequency of point mutations in A1215D and F1538I of the voltage-gated sodium channel gene(VGSC),which may increase resistance to pyrethroids,ranged 88%-100%and 10%-100%,respectively.For target sites related to organophosphate resistance,mutation frequencies ranged 25%-92%for G119S and 0%-23%for A201S in the acetycholinesterase gene(Ace).Mutation G126S in the bifenazate resistance-related cytochrome b gene(Cytb)was observed in three of the seven T.urticae populations.Higher activities of detoxification enzymes(P450,GST,CarEs and UGTs)were observed in two T.urticae populations,with significant difference in the XY-SX population.These results provide useful information on the status of pesticide resistance of T.urticae in China and suggest that T.urticae field populations may have multiple resistance mechanisms.

Modes of action of fraxinellone against the tobacco budworm, Heliothis virescens

Fraxinellone significantly reduced the relative growth rate, food consumption rate as well as the efficiency of conversion of ingested food into biomass of Heliothis virescens when incorporated into artificial diets at concentrations of 4.31 x 10.5 mol/L and above. After being fed with fraxinellone-treated diets for 24 h, the larval midguts of H. vb＇escens possess significantly lower activities of α-amylase and non-specific proteases and higher activities of cytochrome P450s. In vitro, the compound did not inhibit the activities of u-amylase and non-specific proteases extracted from the larval midguts. Clear evidence of post-ingestive toxicity of fraxinellone to midgut cells was observed under an electron microscope. The modes of action of the compound against insects were discussed.