RESUMO
Two cDNA sequences encoding Drosophila Ace-orthologous and -paralogous acetylcholinesterase precursors (AO- and AP-AChE precursors, respectively), were identified from the body louse, Pediculus humanus humanus L. In vitro inhibition studies with an insecticide-susceptible body louse strain exhibited a simplex inhibitory response of AChE. The I50 values of fenitroxon and carbaryl were estimated to be 2.2 and 1.9 microM for the susceptible lice, respectively. The mRNA level of AP-AChE gene was 3.1- and 9.3-fold higher than that of AO-AChE gene in the abdomen and the combined parts of the head and thorax, respectively, suggesting, due to its abundance, the potential significance of the AP-AChE isoform in Pediculus human lice in association with the efficacy of AChE-targeting pediculicides.
Assuntos
Acetilcolinesterase/genética , DNA Complementar/química , Pediculus/genética , Acetilcolinesterase/química , Sequência de Aminoácidos , Animais , Carbaril/toxicidade , Evolução Molecular , Fenitrotion/análogos & derivados , Fenitrotion/toxicidade , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Inseticidas/toxicidade , Dados de Sequência Molecular , Pediculus/efeitos dos fármacos , Alinhamento de SequênciaRESUMO
The problem of pyrethroid-resistance in head lice, Pediculus humanus capitis (De Geer), is growing worldwide, and an insensitive sodium channel is suspected as the major mechanism of this resistance. We sequenced an open reading frame (ORF) encoding for the para-orthologous sodium channel from an insecticide-susceptible strain of the body louse, Pediculus humanus humanus (L.), based on conserved peptide sequences and a known partial gene sequence. Phenothrin-susceptible and -resistant head louse colonies from Japanese were individually analyzed for point mutations of the sodium channel cDNA; susceptible head and body lice differed in double homozygous synonymous substitutions. The resistant head lice shared 23 base substitutions homozygously, in which four resulted in amino acid substitutions: D11E in the N-terminal inner-membrane segment; M850T in the outer-membrane loop between segments four and five of domain II; T952I and L955 F in the trans-membrane segment five of domain II. The latter two substitutions coincided with those of pyrethroid-resistant head lice in the U.S. and U.K. (Lee et al. 2000), within the available published information on the peptide sequences. The potential mechanisms of head louse pyrethroid-resistance are discussed based on the four structural changes of the target molecule.
Assuntos
Resistência a Medicamentos/genética , Inseticidas/toxicidade , Pediculus/genética , Piretrinas/toxicidade , Canais de Sódio/genética , Sequência de Aminoácidos , Animais , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/genética , Mapeamento por Restrição , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Canais de Sódio/químicaRESUMO
We report detection of Bartonella quintana Brenner, the pathogenic agent of trench fever, from body lice, Pediculus humanus L., infesting homeless people in Tokyo by polymerase chain reaction. Two of 12 (16.7%) homeless were infested with Bartonella-positive body lice. From the current status of the recent increase of homeless people in many large cities of the developed countries, a medical examination of homeless people should be carefully performed in the consideration of trench fever. Sampling of body lice from clothing of homeless people is recommended for quick and accurate diagnosis of trench fever through the detection of B. quintana DNA.
