Yan G

References (19)

Title : Non-Coding RNAs Potentially Involved in Pyrethroid Resistance of Anopheles funestus Population in Western Kenya - Debrah_2024_Res.Sq__
Author(s) : Debrah I , Zhong D , Machani MG , Nattoh G , Ochwedo KO , Morang'a CM , Lee MC , Amoah LE , Githeko AK , Afrane YA , Yan G
Ref : Res Sq , : , 2024
Abstract : Backgrounds The resurgence of Anopheles funestus , a dominant vector of human malaria in western Kenya was partly attributed to insecticide resistance. However, evidence on the molecular basis of pyrethroid resistance in western Kenya is limited. Noncoding RNAs (ncRNAs) form a vast class of RNAs that do not code for proteins and are ubiquitous in the insect genome. Here, we demonstrated that multiple ncRNAs could play a potential role in An. funestus resistance to pyrethroid in western Kenya. Materials and Methods Anopheles funestus mosquitoes were sampled by aspiration methods in Bungoma, Teso, Siaya, Port Victoria and Kombewa in western Kenya. The F1 progenies were exposed to deltamethrin (0.05%), permethrin (0.75%), DDT (4%) and pirimiphos-methyl (0.25%) following WHO test guidelines. A synergist assay using piperonyl butoxide (PBO) (4%) was conducted to determine cytochrome P450s' role in pyrethroid resistance. RNA-seq was conducted on a combined pool of specimens that were resistant and unexposed, and the results were compared with those of the FANG susceptible strain. This approach aimed to uncover the molecular mechanisms underlying pyrethroid resistance. Results Pyrethroid resistance was observed in all the sites with an average mortality rate of 57.6%. Port Victoria had the highest level of resistance to permethrin (MR=53%) and deltamethrin (MR=11%) pyrethroids. Teso had the lowest level of resistance to permethrin (MR=70%) and deltamethrin (MR=87%). Resistance to DDT was observed only in Kombewa (MR=89%) and Port Victoria (MR=85%). A full susceptibility to P-methyl (0.25%) was observed in all the sites. PBO synergist assay revealed high susceptibility (>98%) to the pyrethroids in all the sites except for Port Victoria (MR=96%, n=100). Whole transcriptomic analysis showed that most of the gene families associated with pyrethroid resistance comprised non-coding RNAs (67%), followed by imipenemase (10%),cytochrome P450s (6%), cuticular proteins (5%), olfactory proteins (4%), glutathione S-transferases (3%), UDP-glycosyltransferases (2%), ATP-binding cassettes (2%) and carboxylesterases(1%). Conclusions This study unveils the molecular basis of insecticide resistance in An. funestus in western Kenya, highlighting for the first time the potential role of non-coding RNAs in pyrethroid resistance. Targeting non-coding RNAs for intervention development could help in insecticide resistance management.
ESTHER : Debrah_2024_Res.Sq__
PubMedSearch : Debrah_2024_Res.Sq__
PubMedID: 38464038

Title : Emerging Mosquito Resistance to Piperonyl Butoxide-Synergized Pyrethroid Insecticide and Its Mechanism - Zhou_2022_J.Med.Entomol__
Author(s) : Zhou G , Li Y , Jeang B , Wang X , Cummings RF , Zhong D , Yan G
Ref : Journal of Medical Entomology , : , 2022
Abstract : Piperonyl butoxide (PBO)-synergized pyrethroid products are widely available for the control of pyrethroid-resistant mosquitoes. To date, no study has examined mosquito resistance after pre-exposure to PBO and subsequent enzymatic activity when exposed to PBO-synergized insecticides. We used Culex quinquefasciatus Say (Diptera: Culicidae), an important vector of arboviruses and lymphatic filariasis, as a model to examine the insecticide resistance mechanisms of mosquitoes to PBO-synergized pyrethroid using modified World Health Organization tube bioassays and biochemical analysis of metabolic enzyme expressions pre- and post-PBO exposure. Mosquito eggs and larvae were collected from three cities in Orange County in July 2020 and reared in insectary, and F0 adults were used in this study. A JHB susceptible strain was used as a control. Mosquito mortalities and metabolic enzyme expressions were examined in mosquitoes with/without pre-exposure to different PBO concentrations and exposure durations. Except for malathion, wild strain Cx quinquefasciatus mosquitoes were resistant to all insecticides tested, including PBO-synergized pyrethroids (mortality range 3.7 +/- 4.7% to 66.7 +/- 7.7%). Wild strain mosquitoes had elevated levels of carboxylesterase (COE, 3.8-fold) and monooxygenase (P450, 2.1-fold) but not glutathione S-transferase (GST) compared to susceptible mosquitoes. When wild strain mosquitoes were pre-exposed to 4% PBO, the 50% lethal concentration of deltamethrin was reduced from 0.22% to 0.10%, compared to 0.02% for a susceptible strain. The knockdown resistance gene mutation (L1014F) rate was 62% in wild strain mosquitoes. PBO pre-exposure suppressed P450 enzyme expression levels by 25~34% and GST by 11%, but had no impact on COE enzyme expression. Even with an optimal PBO concentration (7%) and exposure duration (3h), wild strain mosquitoes had significantly higher P450 enzyme expression levels after PBO exposure compared to the susceptible laboratory strain. These results further demonstrate other studies that PBO alone may not be enough to control highly pyrethroid-resistant mosquitoes due to multiple resistance mechanisms. Mosquito resistance to PBO-synergized insecticide should be closely monitored through a routine resistance management program for effective control of mosquitoes and the pathogens they transmit.
ESTHER : Zhou_2022_J.Med.Entomol__
PubMedSearch : Zhou_2022_J.Med.Entomol__
PubMedID: 35050361

Title : Insecticide resistance status of indoor and outdoor resting malaria vectors in a highland and lowland site in Western Kenya - Owuor_2021_PLoS.One_16_e0240771
Author(s) : Owuor KO , Machani MG , Mukabana WR , Munga SO , Yan G , Ochomo E , Afrane YA
Ref : PLoS ONE , 16 :e0240771 , 2021
Abstract : BACKGROUND: Long Lasting Insecticidal Nets (LLINs) and indoor residual spraying (IRS) represent powerful tools for controlling malaria vectors in sub-Saharan Africa. The success of these interventions relies on their capability to inhibit indoor feeding and resting of malaria mosquitoes. This study sought to understand the interaction of insecticide resistance with indoor and outdoor resting behavioral responses of malaria vectors from Western Kenya. METHODS: The status of insecticide resistance among indoor and outdoor resting anopheline mosquitoes was compared in Anopheles mosquitoes collected from Kisumu and Bungoma counties in Western Kenya. The level and intensity of resistance were measured using WHO-tube and CDC-bottle bioassays, respectively. The synergist piperonyl butoxide (PBO) was used to determine if metabolic activity (monooxygenase enzymes) explained the resistance observed. The mutations at the voltage-gated sodium channel (Vgsc) gene and Ace 1 gene were characterized using PCR methods. Microplate assays were used to measure levels of detoxification enzymes if present. RESULTS: A total of 1094 samples were discriminated within Anopheles gambiae s.l. and 289 within An. funestus s.l. In Kisian (Kisumu county), the dominant species was Anopheles arabiensis 75.2% (391/520) while in Kimaeti (Bungoma county) collections the dominant sibling species was Anopheles gambiae s.s 96.5% (554/574). The An. funestus s.l samples analysed were all An. funestus s.s from both sites. Pyrethroid resistance of An.gambiae s.l F1 progeny was observed in all sites. Lower mortality was observed against deltamethrin for the progeny of indoor resting mosquitoes compared to outdoor resting mosquitoes (Mortality rate: 37% vs 51%, P = 0.044). The intensity assays showed moderate-intensity resistance to deltamethrin in the progeny of mosquitoes collected from indoors and outdoors in both study sites. In Kisian, the frequency of vgsc-L1014S and vgsc-L1014F mutation was 0.14 and 0.19 respectively in indoor resting malaria mosquitoes while those of the outdoor resting mosquitoes were 0.12 and 0.12 respectively. The ace 1 mutation was present in higher frequency in the F1 of mosquitoes resting indoors (0.23) compared to those of mosquitoes resting outdoors (0.12). In Kimaeti, the frequencies of vgsc-L1014S and vgsc-L1014F were 0.75 and 0.05 respectively for the F1 of mosquitoes collected indoors whereas those of outdoor resting ones were 0.67 and 0.03 respectively. The ace 1 G119S mutation was present in progeny of mosquitoes from Kimaeti resting indoors (0.05) whereas it was absent in those resting outdoors. Monooxygenase activity was elevated by 1.83 folds in Kisian and by 1.33 folds in Kimaeti for mosquitoes resting indoors than those resting outdoors respectively. CONCLUSION: The study recorded high phenotypic, metabolic and genotypic insecticide resistance in indoor resting populations of malaria vectors compared to their outdoor resting counterparts. The indication of moderate resistance intensity for the indoor resting mosquitoes is alarming as it could have an operational impact on the efficacy of the existing pyrethroid based vector control tools. The use of synergist (PBO) in LLINs may be a better alternative for widespread use in these regions recording high insecticide resistance.
ESTHER : Owuor_2021_PLoS.One_16_e0240771
PubMedSearch : Owuor_2021_PLoS.One_16_e0240771
PubMedID: 33647049

Title : A dual-signal sensor for the analysis of parathion-methyl using silver nanoparticles modified with graphitic carbon nitride - Li_2021_J.Pharm.Anal_11_183
Author(s) : Li Y , Wan M , Yan G , Qiu P , Wang X
Ref : J Pharm Anal , 11 :183 , 2021
Abstract : A highly sensitive and selective method was developed for both UV-vis spectrophotometric and fluorimetric determination of organophosphorus pesticides (OPs). This method used silver nanoparticles (AgNPs) modified with graphitic carbon nitride (g-C(3)N(4)). The AgNPs reduced the fluorescence intensity of g-C(3)N(4). Acetylthiocholine (ATCh) could be catalytically hydrolyzed by acetylcholinesterase (AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-C(3)N(4), with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 microg/L (S/N = 3). In addition, the absorption of the g-C(3)N(4)/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.
ESTHER : Li_2021_J.Pharm.Anal_11_183
PubMedSearch : Li_2021_J.Pharm.Anal_11_183
PubMedID: 34012694

Title : Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya - Orondo_2021_Parasit.Vectors_14_335
Author(s) : Orondo PW , Nyanjom SG , Atieli H , Githure J , Ondeto BM , Ochwedo KO , Omondi CJ , Kazura JW , Lee MC , Zhou G , Zhong D , Githeko AK , Yan G
Ref : Parasit Vectors , 14 :335 , 2021
Abstract : BACKGROUND: Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. METHODS: The study was carried out in 2018-2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. RESULTS: Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8-84% to 83.3-78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1-16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. CONCLUSION: Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.
ESTHER : Orondo_2021_Parasit.Vectors_14_335
PubMedSearch : Orondo_2021_Parasit.Vectors_14_335
PubMedID: 34174946

Title : Phenotypic, genotypic and biochemical changes during pyrethroid resistance selection in Anopheles gambiae mosquitoes - Machani_2020_Sci.Rep_10_19063
Author(s) : Machani MG , Ochomo E , Zhong D , Zhou G , Wang X , Githeko AK , Yan G , Afrane YA
Ref : Sci Rep , 10 :19063 , 2020
Abstract : The directional selection for insecticide resistance due to indiscriminate use of insecticides in public health and agricultural system favors an increase in the frequency of insecticide-resistant alleles in the natural populations. Similarly, removal of selection pressure generally leads to decay in resistance. Past investigations on the emergence of insecticide resistance in mosquitoes mostly relied on field survey of resistance in vector populations that typically had a complex history of exposure to various public health and agricultural pest control insecticides in nature, and thus the effect of specific insecticides on rate of resistance emergency or resistance decay rate is not known. This study examined the phenotypic, genotypic, and biochemical changes that had occurred during the process of selection for pyrethroid resistance in Anopheles gambiae, the most important malaria vector in Africa. In parallel, we also examined these changes in resistant populations when there is no selection pressure applied. Through repeated deltamethrin selection in adult mosquitoes from a field population collected in western Kenya for 12 generations, we obtained three independent and highly pyrethroid-resistant An. gambiae populations. Three susceptible populations from the same parental population were generated by removing selection pressure. These two lines of mosquito populations differed significantly in monooxygenase and beta-esterase activities, but not in Vgsc gene mutation frequency, suggesting metabolic detoxification mechanism plays a major role in generating moderate-intensity resistance or high-intensity resistance. Pre-exposure to the synergist piperonyl butoxide restored the susceptibility to insecticide among the highly resistant mosquitoes, confirming the role of monooxygenases in pyrethroid resistance. The rate of resistance decay to become fully susceptible from moderate-intensity resistance took 15 generations, supporting at least 2-years interval is needed when the rotational use of insecticides with different modes of action is considered for resistance management.
ESTHER : Machani_2020_Sci.Rep_10_19063
PubMedSearch : Machani_2020_Sci.Rep_10_19063
PubMedID: 33149227

Title : DNA damage, immunotoxicity, and neurotoxicity induced by deltamethrin on the freshwater crayfish, Procambarus clarkii - Hong_2020_Environ.Toxicol__
Author(s) : Hong Y , Huang Y , Yan G , Yin H , Huang Z
Ref : Environ Toxicol , : , 2020
Abstract : Pyrethroid pesticides are applied to both agricultural and aquacultural industries for pest control. However, information of their impact on the commercial important freshwater crayfish, Procambarus clarkii is scarce. Therefore, the present study aimed to characterize to effects of a commonly used pyrethroid pesticide, deltamethrin on DNA damage, immune response, and neurotoxicity in P. clarkii. Animals were exposed to 7, 14, and 28 ng/L of deltamethrin, which correspond to 1/8, 1/4, and 1/2 of the LC(50) (96 hours) of this pyrethroid to P. clarkii. Significant increase of olive tail moment (OTM) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was found after deltamethrin exposure in a dose-dependent way. Total hemocyte counts (THC) and activities of immune-related enzymes including acid phosphatase (ACP), lysozyme (LZM), and phenoloxidase (PO) were all decreased and significantly lower than control at concentration of 28 ng/L after 96 hours exposure. Acetylcholinesterase (AChE) activity, an indicator of neurotoxic effect was investigated and it was decreased significantly in muscles at 14 and 28 ng/L after 24 hours exposure. The level of intracellular reactive oxygen species (ROS) in hemocytes was also measured and the significant increase of ROS was found at 14 and 28 ng/L concentrations. The results revealed that deltamethrin induced DNA damage, immunotoxicity, and neurotoxicity in P. clarkii by excessive generation of ROS. Because of the dose-dependent responses of all parameters under exposure of deltamethrin at environmentally realistic concentrations, these parameters could be used as sensitive biomarkers for risk assessment of deltamethrin in aquaculture area.
ESTHER : Hong_2020_Environ.Toxicol__
PubMedSearch : Hong_2020_Environ.Toxicol__
PubMedID: 32757256

Title : Widespread Multiple Insecticide Resistance in the Major Dengue Vector Aedes albopictus in Hainan Province, China - Li_2020_Pest.Manag.Sci_77_1945
Author(s) : Li Y , Zhou G , Zhong D , Wang X , Hemming-Schroeder E , David RE , Lee MC , Zhong S , Yi G , Liu Z , Cui G , Yan G
Ref : Pest Manag Sci , 77 :1945 , 2020
Abstract : BACKGROUND: Aedes albopictus is a highly invasive mosquito and has become a potential vector of dengue, chikungunya and Zika viruses. Insecticide-based mosquito interventions are the main tools for vector-borne disease control. However, mosquito resistance to insecticides is a major threat to effective prevention and control. Five Ae. albopictus populations across Hainan Province, China were investigated for susceptibility to multiple insecticides and resistance mechanisms. RESULTS: Larval bioassays indicated that resistance to pyrethroids was common in all larval populations. Adult bioassays revealed all populations were either resistant or highly resistant to at least 4 of the 6 synthetic insecticides (deltamethrin, permethrin, cyfluthrin, propoxur, malathion, and DDT) tested. Pre-exposure of mosquitoes to the synergistic agent piperonyl butoxide (PBO) increased mosquito mortality by 2.4-43.3% in bioassays to DDT, malathion, and permethrin and rendered mosquito sensitive to deltamethrin, cyfluthrin, and propoxur. The frequency of knockdown resistance (kdr) mutations (F1534S and F1534C) ranged from 69.8% to 89.3% and from 38.1% to 87.0% in field resistant and sensitive populations, respectively. F1534S mutation was significantly associated with pyrethroid resistance. No mutation was detected in acetylcholinesterase (ace-1) gene in the two examined populations. CONCLUSION: This study provides evidence of widespread resistance to multiple insecticides in Ae. albopictus in Hainan Province, China. Both kdr mutations and metabolic detoxification were the potential causes of insecticide resistance for Ae. albopictus. Our findings highlight the need for insecticide resistance management and mosquito control measures that do not entirely depend on synthetic insecticides.
ESTHER : Li_2020_Pest.Manag.Sci_77_1945
PubMedSearch : Li_2020_Pest.Manag.Sci_77_1945
PubMedID: 33301644

Title : Fast emerging insecticide resistance in Aedes albopictus in Guangzhou, China: Alarm to the dengue epidemic - Su_2019_PLoS.Negl.Trop.Dis_13_e0007665
Author(s) : Su X , Guo Y , Deng J , Xu J , Zhou G , Zhou T , Li Y , Zhong D , Kong L , Wang X , Liu M , Wu K , Yan G , Chen XG
Ref : PLoS Negl Trop Dis , 13 :e0007665 , 2019
Abstract : Dengue is one of the most serious mosquito-borne infectious diseases in the world. Aedes albopictus is the most invasive mosquito and one of the primary vectors of dengue. Vector control using insecticides is the only viable strategy to prevent dengue virus transmission. In Guangzhou, after the 2014 pandemic, massive insecticides have been implemented. Massive insecticide use may lead to the development of resistance, but few reports are available on the status of insecticide resistance in Guangzhou after 2014. In this study, Ae. albopictus were collected from four districts with varied dengue virus transmission intensity in Guangzhou from 2015 to 2017. Adult Ae. albopictus insecticide susceptibility to deltamethrin (0.03%), permethrin(0.25%), DDT(4%), malathion (0.8%) and bendiocarb (0.1%) was determined by the standard WHO tube test, and larval resistance bioassays were conducted using temephos, Bacillus thuringiensis israelensis (Bti), pyriproxyfen (PPF) and hexaflumuron. Mutations at the voltage-gated sodium channel (VGSC) gene and acetylcholinesterase (AChE) gene were analyzed. The effect of cytochrome P450s on the resistance of Ae. albopictus to deltamethrin was tested using the synergistic agent piperonyl butoxide (PBO). The results showed that Ae. albopictus populations have rapidly developed very high resistances to multiple commonly used insecticides at all study areas except malathion, Bti and hexaflumuron. We found 1534 codon mutations in the VGSC gene that were significantly correlated with the resistance to pyrethroids and DDT, and 11 synonymous mutations were also found in the gene. The resistance to deltamethrin can be significantly reduced by PBO but may generated cross-resistance to PPF. Fast emerging resistance in Ae. albopictus may affect mosquito management and threaten the prevention and control of dengue, similar to the resistance in Anopheles mosquitoes has prevented the elimination of malaria and call for timely and guided insecticide management.
ESTHER : Su_2019_PLoS.Negl.Trop.Dis_13_e0007665
PubMedSearch : Su_2019_PLoS.Negl.Trop.Dis_13_e0007665
PubMedID: 31525199

Title : Insecticide Resistance Status and Mechanisms of Anopheles sinensis (Diptera: Culicidae) in Wenzhou, an Important Coastal Port City in China - Chen_2019_J.Med.Entomol_56_803
Author(s) : Chen S , Qin Q , Zhong D , Fang X , He H , Wang L , Dong L , Lin H , Zhang M , Cui L , Yan G
Ref : Journal of Medical Entomology , 56 :803 , 2019
Abstract : Although scaled-up interventions and effective control efforts have drastically reduced malaria morbidity and mortality, malaria remains a serious threat to public health worldwide. Anopheles sinensis Wiedemann 1828 is a historically important vector of Plasmodium vivax (Haemosporida: Plasmodiidae) malaria in China. Insecticide resistance has become a major obstacle to vector-borne disease control. However, little is known about the insecticide resistance of An. sinensis in Wenzhou, an important coastal port city in Zhejiang province, China. The aim of this study was to examine insecticide resistance and mechanisms in An. sinensis field mosquito populations. Evidence of multiple insecticide resistance was found in An. sinensis adult female populations. Medium to high frequencies of target site kdr together with fixed ace-1 mutations was detected in both the Ruian and Yongjia populations. Both populations showed an association between kdr L1014 mutation and resistance phenotype when tested against deltamethrin and DDT. Significantly different metabolic enzyme activities were found between the susceptible laboratory strain and field-collected mosquitoes from both Ruian and Yongjia. Both field collected An. sinensis populations exhibited significantly higher P450 enzyme activity compared with the laboratory strain, while the field-collected resistant mosquitoes exhibited various GST and COE enzyme activities. These results indicate multiple resistance mechanisms in An. sinensis field populations. Effective implementation of insecticide resistance management strategies is urgently needed. The data collected in this study will be valuable for modeling insecticide resistance spread and vector-control interventions.
ESTHER : Chen_2019_J.Med.Entomol_56_803
PubMedSearch : Chen_2019_J.Med.Entomol_56_803
PubMedID: 30715428

Title : Evidence for multiple-insecticide resistance in urban Aedes albopictus populations in southern China - Li_2018_Parasit.Vectors_11_4
Author(s) : Li Y , Xu J , Zhong D , Zhang H , Yang W , Zhou G , Su X , Wu Y , Wu K , Cai S , Yan G , Chen XG
Ref : Parasit Vectors , 11 :4 , 2018
Abstract : BACKGROUND: Aedes albopictus (Skuse) is an invasive mosquito that has become an important vector of chikungunya, dengue and Zika viruses. In the absence of specific antiviral therapy or a vaccine, vector management is the sole method available for reducing Aedes-induced disease morbidity. Determining the resistance status of Ae. albopictus to insecticides and exploring the resistance mechanisms is essential for future vector control planning. METHODS: Aedes albopictus larvae and pupae were sampled from six sites (two sites each from urban, suburban and rural) in Guangzhou. The resistance bioassays were conducted against Bacillus thuringiensis israelensis (Bti): deltamethrin, propoxur and malathion for larvae; and deltamethrin, DDT, propoxur and malathion for adults. P450 monooxygenase (P450s), glutathione S-transferase (GSTs) and carboxylesterase (COEs) activities of adult mosquitoes were measured. Mutations at the knockdown resistance (kdr) gene were analyzed, and the association between kdr mutations and phenotypic resistance was tested. RESULTS: Adult bioassays revealed varied susceptibility against DDT, deltamethrin and propoxur in the six Ae. albopictus populations. Significantly lower mortality rates were found in urban populations than suburban and rural populations. Urban mosquito populations showed resistance against DDT, deltamethrin and propoxur, while one rural population was resistant to DDT. All populations tested were susceptible to malathion. Larval bioassays results indicated that all populations of Ae. albopictus were sensitive to the larvicide Bti and malathion. Resistance to deltamethrin and propoxur was common in larval populations. The F1534S and F1534 L mutations were found to be significantly associated with deltamethrin resistance. Biochemical assays indicated elevated detoxification enzyme activities in the field mosquito populations. CONCLUSIONS: Aedes albopictus populations in Guangzhou, especially in urban areas, have developed resistance to the commonly used insecticides, primarily DDT and deltamethrin. This finding calls for resistance management and developing counter measures to mitigate the spread of resistance.
ESTHER : Li_2018_Parasit.Vectors_11_4
PubMedSearch : Li_2018_Parasit.Vectors_11_4
PubMedID: 29298700

Title : Antioxidative status, immunological responses, and heat shock protein expression in hepatopancreas of Chinese mitten crab, Eriocheir sinensis under the exposure of glyphosate - Hong_2018_Fish.Shellfish.Immunol_86_840
Author(s) : Hong Y , Huang Y , Yan G , Pan C , Zhang J
Ref : Fish Shellfish Immunol , 86 :840 , 2018
Abstract : As a broad-spectrum herbicide, glyphosate was extensively utilised in China for several decades. The contradiction between glyphosate spraying and crab breeding in the rice-crab co-culture system has become more obvious. In this study, the antioxidative status and immunological responses of Chinese mitten crab, Eriocheir sinensis, under sublethal exposure of glyphosate were investigated by detecting the antioxidative and immune-related enzyme activity, acetylcholinesterase (AChE) activity and relative mRNA expression of heat shock proteins (HSPs) in hepatopancreas. The results showed that high concentrations of glyphosate (44 and 98mg/L) could induce significant alteration of superoxide dismutase (SOD), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP), and phenoloxidase (PO) activities by first rising then falling during the exposure. However, AChE activity in all treatments including 4.4mg/L was inhibited markedly after 6h of exposure. In addition, the relative mRNA expression of HSP 60, HSP 70, and HSP 90 was significantly upregulated at both 48h and 96h. These results revealed that glyphosate has a prominent toxic effect on E. sinensis based on antioxidative and immunological response inhibition and AChE activity reduction even at the lowest concentration of 4.4mg/L, and a protective response by upregulation of HSPs was carried out by the species to ease the environmental stress.
ESTHER : Hong_2018_Fish.Shellfish.Immunol_86_840
PubMedSearch : Hong_2018_Fish.Shellfish.Immunol_86_840
PubMedID: 30572127

Title : Assessment of the oxidative and genotoxic effects of the glyphosate-based herbicide roundup on the freshwater shrimp, Macrobrachium nipponensis - Hong_2018_Chemosphere_210_896
Author(s) : Hong Y , Yang X , Huang Y , Yan G , Cheng Y
Ref : Chemosphere , 210 :896 , 2018
Abstract : In the present study, an acute toxic test was performed to assess the oxidative stress and genotoxic effects of the herbicide on the freshwater shrimp Macrobrachium nipponensis. The results showed that the 48-h and 96-h LC50 values of Roundup to M. nipponensis were 57.684mg/L and 11.237mg/L, respectively. For further investigation, the shrimps were exposed to sublethal concentrations of 0.35, 0.70, 1.40, 2.80 and 5.60mg/L for 96h. A significant decrease in total haemocytes count (THC) was observed at concentration of 5.60mg/L throughout the experiment. The level of superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) in all the treatments decreased in a dose- and time-dependent manner except for the concentration group of 0.35mg/L. The malondialdehyde (MDA), hydrogen peroxide (H2O2) and protein carbonyl in serum increased significantly at concentrations of 2.80mg/L and 5.60mg/L. A significant decrease in acetylcholinesterase (AChE) activity was observed at each concentration (P0.05). In addition, the micronucleus (MN) frequency of haemocytes significantly increased (P0.05) at concentrations of 1.40, 2.80 and 5.60mg/L, whereas the comet ratio and %DNA in the tails exhibited a clear time- and dose-dependent response during the exposure. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants, and this dose-dependent relation suggests the sensitivity and availability of all the biomarkers. These results revealed that Roundup had a prominent toxic effect on M. nipponensis based on the antioxidative response inhibition and genotoxicity.
ESTHER : Hong_2018_Chemosphere_210_896
PubMedSearch : Hong_2018_Chemosphere_210_896
PubMedID: 30208549

Title : Pigment epithelium-derived factor regulates microvascular permeability through adipose triglyceride lipase in sepsis - He_2015_Clin.Sci.(Lond)_129_49
Author(s) : He T , Hu J , Yan G , Li L , Zhang D , Zhang Q , Chen B , Huang Y
Ref : Clinical Science (Lond) , 129 :49 , 2015
Abstract : The integrity of the vascular barrier, which is essential to blood vessel homoeostasis, can be disrupted by a variety of soluble permeability factors during sepsis. Pigment epithelium-derived factor (PEDF), a potent endogenous anti-angiogenic molecule, is significantly increased in sepsis, but its role in endothelial dysfunction has not been defined. To assess the role of PEDF in the vasculature, we evaluated the effects of exogenous PEDF in vivo using a mouse model of cecal ligation and puncture (CLP)-induced sepsis and in vitro using human dermal microvascular endothelial cells (HDMECs). In addition, PEDF was inhibited using a PEDF-monoclonal antibody (PEDF-mAb) or recombinant lentivirus vectors targeting PEDF receptors, including adipose triglyceride lipase (ATGL) and laminin receptor (LR). Our results showed that exogenous PEDF induced vascular hyperpermeability, as measured by extravasation of Evan's Blue (EB), dextran and microspheres in the skin, blood, trachea and cremaster muscle, both in a normal state and under conditions of sepsis. In control and LR-shRNA-treated HDMECs, PEDF alone or in combination with inflammatory mediators resulted in activation of RhoA, which was accompanied by actin rearrangement and disassembly of intercellular junctions, impairing endothelial barrier function. But in ATGL-shRNA-treated HDMECs, PEDF failed to induce the aforementioned alterations, suggesting that PEDF-induced hyperpermeability was mediated through the ATGL receptor. These results reveal a novel role for PEDF as a potential vasoactive substance in septic vascular hyperpermeability. Furthermore, our results suggest that PEDF and ATGL may serve as therapeutic targets for managing vascular hyperpermeability in sepsis.
ESTHER : He_2015_Clin.Sci.(Lond)_129_49
PubMedSearch : He_2015_Clin.Sci.(Lond)_129_49
PubMedID: 25700221

Title : Genome sequence of the Asian Tiger mosquito, Aedes albopictus, reveals insights into its biology, genetics, and evolution - Chen_2015_Proc.Natl.Acad.Sci.U.S.A_112_E5907
Author(s) : Chen XG , Jiang X , Gu J , Xu M , Wu Y , Deng Y , Zhang C , Bonizzoni M , Dermauw W , Vontas J , Armbruster P , Huang X , Yang Y , Zhang H , He W , Peng H , Liu Y , Wu K , Chen J , Lirakis M , Topalis P , Van Leeuwen T , Hall AB , Thorpe C , Mueller RL , Sun C , Waterhouse RM , Yan G , Tu ZJ , Fang X , James AA
Ref : Proc Natl Acad Sci U S A , 112 :E5907 , 2015
Abstract : The Asian tiger mosquito, Aedes albopictus, is a highly successful invasive species that transmits a number of human viral diseases, including dengue and Chikungunya fevers. This species has a large genome with significant population-based size variation. The complete genome sequence was determined for the Foshan strain, an established laboratory colony derived from wild mosquitoes from southeastern China, a region within the historical range of the origin of the species. The genome comprises 1,967 Mb, the largest mosquito genome sequenced to date, and its size results principally from an abundance of repetitive DNA classes. In addition, expansions of the numbers of members in gene families involved in insecticide-resistance mechanisms, diapause, sex determination, immunity, and olfaction also contribute to the larger size. Portions of integrated flavivirus-like genomes support a shared evolutionary history of association of these viruses with their vector. The large genome repertory may contribute to the adaptability and success of Ae. albopictus as an invasive species.
ESTHER : Chen_2015_Proc.Natl.Acad.Sci.U.S.A_112_E5907
PubMedSearch : Chen_2015_Proc.Natl.Acad.Sci.U.S.A_112_E5907
PubMedID: 26483478
Gene_locus related to this paper: aedae-q177c7 , aedal-a0a182gwe3 , aedal-a0a182gwt8 , aedal-a0a023eq67

Title : Insecticide resistance of Anopheles sinensis and An. vagus in Hainan Island, a malaria-endemic area of China - Qin_2014_Parasit.Vectors_7_92
Author(s) : Qin Q , Li Y , Zhong D , Zhou N , Chang X , Li C , Cui L , Yan G , Chen XG
Ref : Parasit Vectors , 7 :92 , 2014
Abstract : BACKGROUND: Malaria is one of the most important public health problems in Southeast Asia, including Hainan Island, China. Vector control is the main malaria control measure, and insecticide resistance is a major concern for the effectiveness of chemical insecticide control programs. The objective of this study is to determine the resistance status of the main malaria vector species to pyrethroids and other insecticides recommended by the World Health Organization (WHO) for indoor residual sprays.
METHODS: The larvae and pupae of Anopheles mosquitoes were sampled from multiple sites in Hainan Island, and five sites yielded sufficient mosquitoes for insecticide susceptibility bioassays. Bioassays of female adult mosquitoes three days after emergence were conducted in the two most abundant species, Anopheles sinensis and An. vagus, using three insecticides (0.05% deltamethrin, 4% DDT, and 5% malathion) and following the WHO standard tube assay procedure. P450 monooxygenase, glutathione S-transferase and carboxylesterase activities were measured. Mutations at the knockdown resistance (kdr) gene and the ace-1 gene were detected by DNA sequencing and PCR-RFLP analysis, respectively.
RESULTS: An. sinensis and An. vagus were the predominant Anopheles mosquito species. An. sinensis was found to be resistant to DDT and deltamethrin. An. vagus was susceptible to deltamethrin but resistant to DDT and malathion. Low kdr mutation (L1014F) frequency (<10%) was detected in An. sinensis, but no kdr mutation was detected in An. vagus populations. Modest to high (45%-75%) ace-1 mutation frequency was found in An. sinensis populations, but no ace-1 mutation was detected in An. vagus populations. Significantly higher P450 monooxygenase and carboxylesterase activities were detected in deltamethrin-resistant An. sinensis, and significantly higher P450 monooxygenase, glutathione S-transferase and carboxylesterase activities were found in malathion-resistant An. vagus mosquitoes.
CONCLUSIONS: Multiple insecticide resistance was found in An. sinensis and An. vagus in Hainan Island, a malaria-endemic area of China. Cost-effective integrated vector control programs that go beyond synthetic insecticides are urgently needed.
ESTHER : Qin_2014_Parasit.Vectors_7_92
PubMedSearch : Qin_2014_Parasit.Vectors_7_92
PubMedID: 24589247
Gene_locus related to this paper: anoga-ACHE1

Title : Multiple resistances and complex mechanisms of Anopheles sinensis mosquito: a major obstacle to mosquito-borne diseases control and elimination in China - Chang_2014_PLoS.Negl.Trop.Dis_8_e2889
Author(s) : Chang X , Zhong D , Fang Q , Hartsel J , Zhou G , Shi L , Fang F , Zhu C , Yan G
Ref : PLoS Negl Trop Dis , 8 :e2889 , 2014
Abstract : Malaria, dengue fever, and filariasis are three of the most common mosquito-borne diseases worldwide. Malaria and lymphatic filariasis can occur as concomitant human infections while also sharing common mosquito vectors. The overall prevalence and health significance of malaria and filariasis have made them top priorities for global elimination and control programmes. Pyrethroid resistance in anopheline mosquito vectors represents a highly significant problem to malaria control worldwide. Several methods have been proposed to mitigate insecticide resistance, including rotational use of insecticides with different modes of action. Anopheles sinensis, an important malaria and filariasis vector in Southeast Asia, represents an interesting mosquito species for examining the consequences of long-term insecticide rotation use on resistance. We examined insecticide resistance in two An. Sinensis populations from central and southern China against pyrethroids, organochlorines, organophosphates, and carbamates, which are the major classes of insecticides recommended for indoor residual spray. We found that the mosquito populations were highly resistant to the four classes of insecticides. High frequency of kdr mutation was revealed in the central population, whereas no kdr mutation was detected in the southern population. The frequency of G119S mutation in the ace-1 gene was moderate in both populations. The classification and regression trees (CART) statistical analysis found that metabolic detoxification was the most important resistance mechanism, whereas target site insensitivity of L1014 kdr mutation played a less important role. Our results indicate that metabolic detoxification was the dominant mechanism of resistance compared to target site insensitivity, and suggests that long-term rotational use of various insecticides has led An. sinensis to evolve a high insecticide resistance. This study highlights the complex network of mechanisms conferring multiple resistances to chemical insecticides in mosquito vectors and it has important implication for designing and implementing vector resistance management strategies.
ESTHER : Chang_2014_PLoS.Negl.Trop.Dis_8_e2889
PubMedSearch : Chang_2014_PLoS.Negl.Trop.Dis_8_e2889
PubMedID: 24852174

Title : Genome sequencing and comparison of two nonhuman primate animal models, the cynomolgus and Chinese rhesus macaques - Yan_2011_Nat.Biotechnol_29_1019
Author(s) : Yan G , Zhang G , Fang X , Zhang Y , Li C , Ling F , Cooper DN , Li Q , Li Y , van Gool AJ , Du H , Chen J , Chen R , Zhang P , Huang Z , Thompson JR , Meng Y , Bai Y , Wang J , Zhuo M , Wang T , Huang Y , Wei L , Li J , Wang Z , Hu H , Yang P , Le L , Stenson PD , Li B , Liu X , Ball EV , An N , Huang Q , Fan W , Zhang X , Wang W , Katze MG , Su B , Nielsen R , Yang H , Wang X
Ref : Nat Biotechnol , 29 :1019 , 2011
Abstract : The nonhuman primates most commonly used in medical research are from the genus Macaca. To better understand the genetic differences between these animal models, we present high-quality draft genome sequences from two macaque species, the cynomolgus/crab-eating macaque and the Chinese rhesus macaque. Comparison with the previously sequenced Indian rhesus macaque reveals that all three macaques maintain abundant genetic heterogeneity, including millions of single-nucleotide substitutions and many insertions, deletions and gross chromosomal rearrangements. By assessing genetic regions with reduced variability, we identify genes in each macaque species that may have experienced positive selection. Genetic divergence patterns suggest that the cynomolgus macaque genome has been shaped by introgression after hybridization with the Chinese rhesus macaque. Macaque genes display a high degree of sequence similarity with human disease gene orthologs and drug targets. However, we identify several putatively dysfunctional genetic differences between the three macaque species, which may explain functional differences between them previously observed in clinical studies.
ESTHER : Yan_2011_Nat.Biotechnol_29_1019
PubMedSearch : Yan_2011_Nat.Biotechnol_29_1019
PubMedID: 22002653
Gene_locus related to this paper: macfa-BCHE , macfa-g7nzc0 , macfa-g7nze2 , macfa-g7p4b9 , macfa-g7pa87 , macfa-g7pd01 , macfa-g7q259 , macfa-3neur , macfa-g8f585 , macfa-KANSL3 , macfa-q4r8p0 , macfa-SPG21 , macfa-TEX30 , macmu-3neur , macmu-ACHE , macmu-BCHE , macmu-f6sz31 , macmu-f6the6 , macmu-f6zkq5 , macmu-f7buk8 , macmu-f7cfi8 , macmu-f7flv1 , macmu-f7ggk1 , macmu-f7hir7 , macmu-g7n054 , macmu-g7npb8 , macmu-g7nq39 , macmu-KANSL3 , macmu-TEX30 , macfa-g7pgg6 , macmu-g7n4x3 , macfa-g7nzx2 , macfa-g8f4f7 , macmu-f7ba84 , macfa-g7psx7 , macmu-h9er02 , macfa-g8f3k0 , macfa-a0a2k5w1n7 , macmu-g7mxj6 , macfa-g7pbk1 , macfa-a0a2k5urk5 , macfa-a0a2k5wye4 , macfa-g7pe14 , macmu-f7hkw9 , macmu-f7hm08 , macmu-g7mke4 , macfa-g7nxn9 , macmu-a0a1d5rh04 , macmu-h9fud6 , macfa-g8f3e1 , macfa-i7gcw6 , macmu-f6qwx1 , macmu-f7h4t2 , macfa-a0a2k5wkd0 , macfa-a0a2k5v7v4 , macfa-g7p7y3 , macfa-a0a2k5uqq3 , macmu-i2cu80 , macfa-g8f5i1 , macmu-f7h550 , macmu-f7gkb9 , macfa-a0a2k5tui1

Title : A single residual replacement improves the folding and stability of recombinant cassava hydroxynitrile lyase in E. coil - Yan_2003_Biotechnol.Lett_25_1041
Author(s) : Yan G , Cheng S , Zhao G , Wu S , Liu Y , Sun W
Ref : Biotechnol Lett , 25 :1041 , 2003
Abstract : Substitution of Ser113 for Gly113 in the cap domain of hydroxynitrile lyase from Manihot esculenta (MeHNL) was performed by site-directed mutagenesis to improve its self-generated folding and stability under denaturation conditions. The yield of the recombinant mutant HNL1 (mut-HNL1), which had higher specific activity than the wild type HNL0 (wt-HNL0), was increased by 2 to 3-fold. Thermostability of MeHNL was also enhanced, probably due to an increase in content of the beta-strand secondary structure according to CD analysis. Our data in this report suggest that Ser113 significantly contributes to the in vivo folding and stability of MeHNL and demonstrates an economic advantage of mut-HNL1 over the wt-HNL0.
ESTHER : Yan_2003_Biotechnol.Lett_25_1041
PubMedSearch : Yan_2003_Biotechnol.Lett_25_1041
PubMedID: 12889812
Gene_locus related to this paper: manes-hnl