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:Human body lice, Pediculus humanushumanus, are blood-feeding parasites that live in human clothing and feed several times per day.Saliva from louse bites induces local inflammation in the skin, pruiritis,and, if untreated, chronic Pediculosis has systemic negative health effects.Despite the well-established medical importance of body lice and their longstanding coevolution with humans, characterization of their saliva has been very limited.To address this, we extracted RNA and protein from two of the body louse’s morphologically distinct, sets of salivary glands (Bean-shaped and U-shaped) and generated transcript and protein profiles for each.Additionally, we performed fluorescent staining and confocal microscopy on each gland type to enhance descriptions of their morphology and detail their gross cellular architecture and arrangement.Analysis of the body louse salivary gene products and proteins revealed that the overwhelming majority were not closely related to biomolecules of known function; highlighting the organism’s unique and understudied saliva composition.Unexpectedly, and despite the contrasting morphology of the 2 gland types, there was ahigh degree of overlap in the salivary products produced.This finding suggests a strongDarwinian selection pressure to maintain both salivary glands types, given that it would seemingly be simpler to have a single morphologically homogeneous set of salivary glands.Here, we present the first next-generation sequencing and proteomic characterization of the human body louse sialome, discuss the potential physiological importance of louse salivary proteins, and present possible explanations for why lice have such a complex salivary gland organization despite ahigh degree of redundancy in protein repertoires between Bean and U-shaped salivary glands.