Effect of selection for dichlorodiphenyltrichloroethane (DDT) resistance on the uptake and breakdown of DDT in Aedes aegypti L.

1985 ◽  
Vol 27 (1) ◽  
pp. 23-28 ◽  
Author(s):  
H. R. Rathor ◽  
R. J. Wood
Keyword(s):  
Aedes Aegypti ◽  
Ddt Resistance ◽  
Selection For ◽  
Larval Selection

Aedes aegypti larvae and adults were selected to high levels of resistance with dichlorodiphenyltrichloroethane (DDT) along separate lines. The larval-selected line showed three responses associated with larval resistance: (i) increased detoxication of DDT by dehydrochlorination to dichlorodiphenyldichloroethane DDE (demonstrated both in vivo and in vitro), (ii) increased tolerance to unmetabolised ("residual") DDT and, (iii) a reduction in uptake of DDT. Larval selection caused very little change in adult resistance or the uptake of DDT by adults, but there was an increase in dehydrochlorination. In the adult-selected line dehydrochlorination was increased by selection and was significantly correlated with resistance.Key words: DDT, DDE, resistance, Aedes aegypti.

Insecticide Resistance in Mosquitoes and Root Maggots

1964 ◽  
Vol 96 (1-2) ◽  
pp. 100-101
Author(s):  
A. W. A. Brown ◽  
W. Klassen ◽  
M. K. K. Pillai ◽  
G. S. H. Hooper
Keyword(s):  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Resistance Mechanism ◽  
Peritrophic Membrane ◽  
Resistance Level ◽  
Secondary Resistance ◽  
The Past ◽  
Ddt Resistance

This exhibit represents part of the work of the Department of Zoology in the past 5 years, and others who have contributed to it are F. Matsumura, Z. H. Abedi, T. Kimura, P. G. Fast, J. G. Towgood, J. N. Telford and N. H. Khan.The work with the mosquito Aedes aegypti has involved study of 8 susceptible strains. The mechanism of DDT-resistance has been found to be associated with its detoxication by an enzymic process of dehydrochlorination to DDE; the amount of DDE produced has been found to be directly proportional to the resistance level, both by experiments with larvae in vivo and with larval homogenates incubated with DDT and glutathione in vitro. A secondary resistance mechanism in American strains has been a very pronounced secretion and excretion of peritrophic membrane by the larvae.

Improvement of effectiveness in maize breeding

2006 ◽  
Vol 54 (3) ◽  
pp. 351-358 ◽  
Author(s):  
P. Pepó
Keyword(s):  
Recurrent Selection ◽  
Genetic Manipulation ◽  
Field Testing ◽  
Tissue Cultures ◽  
Maize Breeding ◽  
Breeding Programmes ◽  
Speed Up ◽  
Selection For

Plant regeneration via tissue culture is becoming increasingly more common in monocots such as maize (Zea mays L.). Pollen (gametophytic) selection for resistance to aflatoxin in maize can greatly facilitate recurrent selection and the screening of germplasm for resistance at much less cost and in a shorter time than field testing. In vivo and in vitro techniques have been integrated in maize breeding programmes to obtain desirable agronomic attributes, enhance the genes responsible for them and speed up the breeding process. The efficiency of anther and tissue cultures in maize and wheat has reached the stage where they can be used in breeding programmes to some extent and many new cultivars produced by genetic manipulation have now reached the market.

The anterior and posterior ‘stomach’ regions of larval Aedes aegypti midgut: regional specialization of ion transport and stimulation by 5-hydroxytryptamine

1999 ◽  
Vol 202 (3) ◽  
pp. 247-252 ◽  
Author(s):  
T.M. Clark ◽  
A. Koch ◽  
D.F. Moffett
Keyword(s):  
Steady State ◽  
Aedes Aegypti ◽  
Ion Transport ◽  
Malpighian Tubules ◽  
Transport Mechanisms ◽  
Regional Specialization ◽  
Negative Deflection ◽  
Electrical Polarity

The ‘stomach’ region of the larval mosquito midgut is divided into histologically distinct anterior and posterior regions. Anterior stomach perfused symmetrically with saline in vitro had an initial transepithelial potential (TEP) of −66 mV (lumen negative) that decayed within 10–15 min to a steady-state TEP near −10 mV that was maintained for at least 1 h. Lumen-positive TEPs were never observed in the anterior stomach. The initial TEP of the perfused posterior stomach was opposite in polarity, but similar in magnitude, to that of the anterior stomach, measuring +75 mV (lumen positive). This initial TEP of the posterior stomach decayed rapidly at first, then more slowly, eventually reversing the electrical polarity of the epithelium as lumen-negative TEPs were recorded in all preparations within 70 min. Nanomolar concentrations of the biogenic amine 5-hydroxytryptamine (5-HT, serotonin) stimulated both regions, causing a negative deflection of the TEP of the anterior stomach and a positive deflection of the TEP of the posterior stomach. Phorbol 12,13-diacetate also caused a negative deflection of the TEP of the anterior stomach, but had no effect on the TEP of the posterior stomach. These data demonstrate that 5-HT stimulates region-specific ion-transport mechanisms in the stomach of Aedes aegypti and suggest that 5-HT coordinates the actions of the Malpighian tubules and midgut in the maintenance of an appropriate hemolymph composition in vivo.

PROTEÍNA NÃO-ESTRUTURAL (NS1) COMO FERRAMENTA DIAGNÓSTICA PRECOCE E ALVO TERAPÊUTICO NA DENGUE

2021 ◽  
Author(s):  
Ana Vitória Gomes Alves
Keyword(s):  
Aedes Aegypti

Introdução: A dengue é uma arbovirose tropical negligenciada mundialmente, transmitida pelo Aedes aegypti. A proteína não-estrutural 1 (NS1) está presente nos quatro sorotipos da dengue, e é um importante marcador de viremia na fase inicial da doença por ser secretada na circulação durante a replicação viral, está associada a doença clínica grave que se manifesta como febre hemorrágica da dengue (DHF) ou síndrome do choque da dengue pela indução de interleucina (IL) ‐10 e tem sido estudada além de biomarcador para diagnóstico, como alvo terapêutico. Objetivos: Descrever o uso da proteína não estrutural (NS1) para diagnóstico precoce da dengue e como potencial alvo terapêutico. Material e métodos: Foi realizado uma revisão da literatura, onde os artigos foram consultados nas bases de dados científicos: NCBI e Scielo, com os termos: “Dengue”, “NS1”, “Patogênese”, publicados entre 2014 e 2020. Resultados: Estudos mostram que a NS1 contribui na patogênese da doença, ao interagir com o endotélio e induzir vazamento vascular, uma característica clínica da dengue grave, também ativando o sistema complemento e induzindo citocinas imunossupressoras. Por isso, sua detecção precoce contribui para o diagnóstico/tratamento imediato, prevenindo a evolução para formas mais agressivas da doença. Essa proteína também pode ser utilizada para identificar quais pacientes tem chances de desenvolver febre hemorrágica, pois durante a fase inicial da doença os níveis de NS1 são mais altos. Tem sido recomendada a combinação da detecção do antígeno NS1 na circulação e dos anticorpos anti-NS1 para melhorar a sensibilidade e a especificidade do diagnóstico. Em estudos em camundongos, os anticorpos anti-NS1 podem reduzir a replicação viral de células infectadas, bloquear os efeitos patogênicos desencadeados por NS1 in vitro e em in vivo. Conclusão: É necessário o desenvolvimento de novos testes que aumentem a sensibilidade e especificidade do diagnóstico da NS1 e também tratamentos direcionados à NS1 que podem ser úteis na redução da gravidade da doença.

Biochemical and genetic characterization of a yeast TFIID mutant that alters transcription in vivo and DNA binding in vitro

1992 ◽  
Vol 12 (5) ◽  
pp. 2372-2382
Author(s):  
K M Arndt ◽  
S L Ricupero ◽  
D M Eisenmann ◽  
F Winston
Keyword(s):  
Amino Acid ◽  
Dna Binding ◽  
Direct Repeat ◽  
Single Amino Acid ◽  
Wild Type ◽  
Dna Binding Specificity ◽  
Selection For

A mutation in the gene that encodes Saccharomyces cerevisiae TFIID (SPT15), which was isolated in a selection for mutations that alter transcription in vivo, changes a single amino acid in a highly conserved region of the second direct repeat in TFIID. Among eight independent spt15 mutations, seven cause this same amino acid change, Leu-205 to Phe. The mutant TFIID protein (L205F) binds with greater affinity than that of wild-type TFIID to at least two nonconsensus TATA sites in vitro, showing that the mutant protein has altered DNA binding specificity. Site-directed mutations that change Leu-205 to five different amino acids cause five different phenotypes, demonstrating the importance of this amino acid in vivo. Virtually identical phenotypes were observed when the same amino acid changes were made at the analogous position, Leu-114, in the first repeat of TFIID. Analysis of these mutations and additional mutations in the most conserved regions of the repeats, in conjunction with our DNA binding results, suggests that these regions of the repeats play equivalent roles in TFIID function, possibly in TATA box recognition.

scholarly journals Mutagenesis and ultraviolet inactivation of transforming DNA of Haemophilus influenzae complexed with a Bacillus subtilis protein that alters DNA conformation.

1996 ◽  
Vol 43 (1) ◽  
pp. 107-114 ◽  
Author(s):  
J K Setlow ◽  
B C Setlow ◽  
P Setlow
Keyword(s):  
Bacillus Subtilis ◽  
Haemophilus Influenzae ◽  
Dna Conformation ◽  
Erythromycin Resistance ◽  
Bacillus Subtilis Spore ◽  
Pyrimidine Dimers ◽  
Resistance Markers ◽  
Selection For

The wild-type Bacillus subtilis spore protein, SspCwt, binds to DNA in vitro and in vivo and changes the conformation of DNA from B to A. Synthesis of the cloned SspCwt gene in Escherichia coli also causes large increases in mutation frequency. Binding of SspCwt to transforming DNA from Haemophilus influenzae made the DNA resistant to ultraviolet (UV) radiation. The mutant protein, SspCala, which does not bind DNA, did not change the UV resistance. The UV sensitivity of the DNA/SspCwt complex was not increased when the recipients of the DNA were defective in excision of pyrimidine dimers. These data indicate that the H. influenzae excision mechanism does not operate on the spore photoproduct formed by UV irradiation of the complex. Selection for the streptomycin- or erythromycin-resistance markers on the transforming DNA evidenced significant mutations at loci closely linked to these, but not at other loci. SspCwt apparently entered the cell attached to the transforming DNA, and caused mutations in adjacent loci. The amount of such mutations decreased when the transforming DNA was UV irradiated, because UV unlinks linked markers.

scholarly journals Cell-Fusing Agent Virus Reduces Arbovirus Dissemination in Aedes aegypti Mosquitoes In Vivo

2019 ◽  
Vol 93 (18) ◽  
Author(s):  
Artem Baidaliuk ◽  
Elliott F. Miot ◽  
Sebastian Lequime ◽  
Isabelle Moltini-Conclois ◽  
Fanny Delaigue ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Dengue Virus ◽  
Cell Line ◽  
Content Type ◽  
Cells In Culture ◽  
Mosquito Cells ◽  
Wide Range ◽  
Natural Hosts

ABSTRACT Aedes aegypti mosquitoes are the main vectors of arthropod-borne viruses (arboviruses) of public health significance, such as the flaviviruses dengue virus (DENV) and Zika virus (ZIKV). Mosquitoes are also the natural hosts of a wide range of viruses that are insect specific, raising the question of their influence on arbovirus transmission in nature. Cell-fusing agent virus (CFAV) was the first described insect-specific flavivirus, initially discovered in an A. aegypti cell line and subsequently detected in natural A. aegypti populations. It was recently shown that DENV and the CFAV strain isolated from the A. aegypti cell line have mutually beneficial interactions in mosquito cells in culture. However, whether natural strains of CFAV and DENV interact in live mosquitoes is unknown. Using a wild-type CFAV isolate recently derived from Thai A. aegypti mosquitoes, we found that CFAV negatively interferes with both DENV type 1 and ZIKV in vitro and in vivo. For both arboviruses, prior infection by CFAV reduced the dissemination titer in mosquito head tissues. Our results indicate that the interactions observed between arboviruses and the CFAV strain derived from the cell line might not be a relevant model of the viral interference that we observed in vivo. Overall, our study supports the hypothesis that insect-specific flaviviruses may contribute to reduce the transmission of human-pathogenic flaviviruses. IMPORTANCE The mosquito Aedes aegypti carries several arthropod-borne viruses (arboviruses) that are pathogenic to humans, including dengue and Zika viruses. Interestingly, A. aegypti is also naturally infected with insect-only viruses, such as cell-fusing agent virus. Although interactions between cell-fusing agent virus and dengue virus have been documented in mosquito cells in culture, whether wild strains of cell-fusing agent virus interfere with arbovirus transmission by live mosquitoes was unknown. We used an experimental approach to demonstrate that cell-fusing agent virus infection reduces the propagation of dengue and Zika viruses in A. aegypti mosquitoes. These results support the idea that insect-only viruses in nature can modulate the ability of mosquitoes to carry arboviruses of medical significance and that they could possibly be manipulated to reduce arbovirus transmission.

scholarly journals Differential replication of dengue virus serotypes 2 and 3 in coinfections of C6/36 cells and Aedes aegypti mosquitoes

2014 ◽  
Vol 8 (07) ◽  
pp. 876-884 ◽  
Author(s):  
Diana Carolina Quintero-Gil ◽  
Marta Ospina ◽  
Jorge Emilio Osorio-Benitez ◽  
Marlen Martinez-Gutierrez
Keyword(s):  
Aedes Aegypti ◽  
Dengue Virus ◽  
Cell Viability ◽  
Denv Infection ◽  
Replication Capacity ◽  
Denv Serotypes ◽  
Viral Genomes ◽  
Diphenyltetrazolium Bromide

Introduction: Different dengue virus (DENV) serotypes have been associated with greater epidemic potential. In turn, the increased frequency in cases of severe forms of dengue has been associated with the cocirculation of several serotypes. Because Colombia is a country with an endemic presence of all four DENV serotypes, the aim of this study was to evaluate the in vivo and in vitro replication of the DENV-2 and DENV-3 strains under individual infection and coinfection conditions. Methodology: C6/36HT cells were infected with the two strains individually or simultaneously (coinfection). Replication capacity was evaluated by RT-qPCR, and the effects on cell viability were assessed with an MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Additionally, Aedes aegypti mosquitoes were artificially fed the two strains of each serotype individually or simultaneously. The viral genomes were quantified by RT-qPCR and the survival of the infected mosquitoes was compared to that of uninfected controls. Results: In single infections, three strains significantly affected C6/36HT cell viability, but no significant differences were found in the replication capacities of the strains of the same serotype. In the in vivo infections, mosquito survival was not affected, and no significant differences in replication between strains of the same serotype were found. Finally, in coinfections, serotype 2 replicated with a thousandfold greater efficiency than serotype 3 did both in vitro and in vivo. Conclusions: Due to the cocirculation of serotypes in endemic regions, further studies of coinfections in a natural environment would further an understanding of the transmission dynamics that affect DENV infection epidemiology.

scholarly journals Multiple gonococcal opacity proteins are expressed during experimental urethral infection in the male.

1994 ◽  
Vol 179 (3) ◽  
pp. 911-920 ◽  
Author(s):  
A E Jerse ◽  
M S Cohen ◽  
P M Drown ◽  
L G Whicker ◽  
S F Isbey ◽  
...  
Keyword(s):  
Antigenic Variation ◽  
Outer Membrane Proteins ◽  
Predominant Type ◽  
Detectable Difference ◽  
Single Protein ◽  
Selection For ◽  
Opacity Proteins ◽  
Strain Fa1090

The opacity (Opa) proteins of Neisseria gonorrhoeae are a family of outer membrane proteins demonstrating phase and antigenic variation. N. gonorrhoeae strain FA0190 has 11 opa loci that encode at least 8 antigenically distinct Opa proteins. To determine if expression of one Opa protein or a subset of them is favored during gonococcal infection, we inoculated Opa-negative variants of strain FA1090 intraurethrally into male volunteers. The Opa phenotype of gonococci isolated from urine and urethral swab cultures from nine infected subjects was determined. Opa proteins were expressed in a large proportion of the reisolates from the infected subjects. Gonococci cultured from urine or urethral swab samples from six of the subjects were uniformly Opa positive, with the predominant Opa variants differing among subjects. Three different Opa proteins were represented as the predominant type in at least one subject each. In three subjects, there was more heterogeneity in Opa phenotype of the reisolates, including the presence of Opa-negative variants. An increase in the proportion of isolates expressing multiple Opa proteins occurred over time in most subjects. Passage of the inoculum in vitro did not result in similar changes in Opa expression. There was no detectable difference in infectivity of an Opa-negative variant and one expressing an Opa protein (OpaF) that was highly represented in reisolates from the original nine subjects. Reisolates from three infected volunteers inoculated with the OpaF variant showed continued expression of OpaF alone or in conjunction with other Opa proteins. These results demonstrate that there is strong selection for expression of one or more Opa proteins by strain FA1090 in vivo, but that no single protein is preferentially expressed during early infection in the male urethra.

scholarly journals A COUP-TF/Svp homolog is highly expressed during vitellogenesis in the mosquito Aedes aegypti

2002 ◽  
Vol 29 (2) ◽  
pp. 223-238 ◽  
Author(s):  
K Miura ◽  
J Zhu ◽  
NT Dittmer ◽  
L Chen ◽  
AS Raikhel
Keyword(s):  
Aedes Aegypti ◽  
Blood Meal ◽  
Fat Body ◽  
Sequence Similarity ◽  
Amino Acid Sequence Similarity ◽  
Receptor Complex ◽  
Ecdysone Receptor ◽  
Ecdysteroid Receptor

In the mosquito Aedes aegypti, vitellogenesis is activated via an ecdysteroid hormonal cascade initiated by a blood meal. The functional ecdysone receptor is a heterodimer composed of the ecdysone receptor (EcR) and ultraspiracle, the homolog of the retinoid X receptor. The precise tuning of this hormonal response requires participation of both positive and negative transcriptional regulators. In Drosophila, Svp, a homolog of chicken ovalbumin upstream promoter transcription factor (COUP-TF), inhibits ecdysone receptor complex-mediated transactivation in vitro and in vivo. Here we report the cloning and characterization of the Svp homolog in mosquito Aedes aegypti, AaSvp. It possesses a high degree of amino acid sequence similarity to the members of the COUP-TF/Svp subfamily. AaSvp transcripts and protein are present in the fat body at high levels from the state of arrest to about 60 h post blood meal. AaSvp binds strongly to a variety of direct repeats of the sequence AGGTCA, but weakly to inverted repeats such as hsp27 EcRE. Transient transfection assays in Drosophila S2 cells showed that AaSvp was able to repress 20-hydroxyecdysone (20E)-dependent transactivation mediated by the mosquito ecdysteroid receptor complex. These data suggest that AaSvp negatively regulates the 20E signaling in the fat body during mosquito vitellogenesis.

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