Project description:Basic helix-loop-helix (bHLH) proteins comprise a large superfamily of transcription factors, which are involved in the regulation of various developmental processes. bHLH family members are widely distributed in various eukaryotes including yeast, fruit fly, zebrafish, mouse, and human. In this study, we identified 55 bHLH motifs encoded in genome sequence of the human body louse, Pediculus humanus corporis (Phthiraptera: Pediculidae). Phylogenetic analyses of the identified P. humanus corporis bHLH (PhcbHLH) motifs revealed that there are 23, 11, 9, 1, 10, and 1 member(s) in groups A, B, C, D, E, and F, respectively. Examination to GenBank annotations of the 55 PhcbHLH members indicated that 29 PhcbHLH proteins were annotated in consistence with our analytical result, 8 were annotated different with our analytical result, 12 were merely annotated as hypothetical protein, and the rest 6 were not deposited in GenBank. A comparison on insect bHLH gene composition revealed that human body louse possibly has more hairy and E(spl) genes than other insect species. Because hairy and E(spl) genes have been found to negatively regulate the differentiation of insect preneural cells, it is suggested that the existence of additional hairy and E(spl) genes in human body louse is probably the consequence of its long period adaptation to the relatively dark and stable environment. These data provide good references for further studies on regulatory functions of bHLH proteins in the growth and development of human body louse.
Project description:Louse-borne diseases are prevalent in the homeless, and body louse eradication has thus far been unsuccessful in this population. We aim to develop a rapid and robust genotyping method usable in large field-based clinical studies to monitor permethrin resistance in the human body louse Pediculus humanus corporis. We assessed a melting curve analysis genotyping method based on real-time PCR using hybridization probes to detect the M815I-T917I-L920F knockdown resistance (kdr) mutation in the paraorthologous voltage-sensitive sodium channel (VSSC) ? subunit gene, which is associated with permethrin resistance. The 908-bp DNA fragment of the VSSC gene, encoding the ? subunit of the sodium channel and encompassing the three mutation sites, was PCR sequenced from 65 lice collected from a homeless population. We noted a high prevalence of the 3 indicated mutations in the body lice collected from homeless people (100% for the M815I and L920F mutations and 56.73% for the T917I mutation). These results were confirmed by melting curve analysis genotyping, which had a calculated sensitivity of 100% for the M815I and T917I mutations and of 98% for the L920F mutation. The specificity was 100% for M815I and L920F and 96% for T917I. Melting curve analysis genotyping is a fast, sensitive, and specific tool that is fully compatible with the analysis of a large number of samples in epidemiological surveys, allowing the simultaneous genotyping of 96 samples in just over an hour (75 min). Thus, it is perfectly suited for the epidemiological monitoring of permethrin resistance in human body lice in large-scale clinical studies.
Project description:Insect reproduction is extremely variable, but the implications of alternative genetic systems are often overlooked in studies on the evolution of insecticide resistance. Both ecotypes of Pediculus humanus (Phthiraptera: Pediculidae), the human head and body lice, are human ectoparasites, the control of which is challenged by the recent spread of resistance alleles. The present study conclusively establishes for the first time that both head and body lice reproduce through paternal genome elimination (PGE), an unusual genetic system in which males transmit only their maternally derived chromosomes. Here, we investigate inheritance patterns of parental genomes using a genotyping approach across families of both ecotypes and show that heterozygous males exclusively or preferentially pass on one allele only, whereas females transmit both in a Mendelian fashion. We do however observe occasional transmission of paternal chromosomes through males, representing the first known case of PGE in which whole-genome meiotic drive is incomplete. Finally, we discuss the potential implications of this finding for the evolution of resistance and invite the development of new theoretical models of how this knowledge might contribute to increasing the success of pediculicide-based management schemes.