Genome sequences of the human body louse and its primary endosymbiont provide insights into the permanent parasitic lifestyle.

As an obligatory parasite of humans, the body louse (Pediculus humanus humanus) is an important vector for human diseases, including epidemic typhus, relapsing fever, and trench fever. Here, we present genome sequences of the body louse and its primary bacterial endosymbiont Candidatus Riesia pediculicola. The body louse has the smallest known insect genome, spanning 108 Mb. Despite its status as an obligate parasite, it retains a remarkably complete basal insect repertoire of 10,773 protein-coding genes and 57 microRNAs. Representing hemimetabolous insects, the genome of the body louse thus provides a reference for studies of holometabolous insects. Compared with other insect genomes, the body louse genome contains significantly fewer genes associated with environmental sensing and response, including odorant and gustatory receptors and detoxifying enzymes. The unique architecture of the 18 minicircular mitochondrial chromosomes of the body louse may be linked to the loss of the gene encoding the mitochondrial single-stranded DNA binding protein. The genome of the obligatory louse endosymbiont Candidatus Riesia pediculicola encodes less than 600 genes on a short, linear chromosome and a circular plasmid. The plasmid harbors a unique arrangement of genes required for the synthesis of pantothenate, an essential vitamin deficient in the louse diet. The human body louse, its primary endosymbiont, and the bacterial pathogens that it vectors all possess genomes reduced in size compared with their free-living close relatives. Thus, the body louse genome project offers unique information and tools to use in advancing understanding of coevolution among vectors, symbionts, and pathogens.

CBX3/heterochromatin protein 1 gamma is significantly upregulated in patients with non-small cell lung cancer.

AIM: Lung cancer is typically categorized into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC comprises of the majority of lung cancer with a poor prognosis in advanced cases. Transcriptional profiling studies, including microarrays and RNA-sequencing studies, have significantly enriched our knowledge of gene expression patterns in NSCLC. A recent transcriptional profiling study identified high prevalence of CBX3/HP1-gamma upregulation in human NSCLC samples. CBX3/HP1-gamma is an isoform of the heterochromatin protein 1 family, which plays a role in heterochromatin formation and is linked to cancer. METHODS: We examined lung cancer samples from our hospital using immunohistochemistry for CBX3/HP1-gamma staining. We also analyzed publicly available databases of NSCLC transcriptional profiling to validate our results. RESULTS: We identified a high prevalence (77.2%) of samples with positive CBX3/HP1-gamma staining by immunohistochemistry in NSCLC patient samples. Independently, we queried a publicly available dataset (GSE40419) containing RNA-seq data from 77 patients. Upregulation of CBX3/HP1-gamma in tumor samples was present in 60.2% of the patients. A similar correlation was also observed in the The Cancer Genome Atlas (TCGA) database. Interestingly, we discovered a highly significant association between positive CBX3/HP1-gamma staining and EGFR mutation in our patient samples (40 of 42 patients, P < 0.001). Treatment of EGFR mutant NSCLC cell lines with the EGFR inhibitor gefitinib failed to yield a change in CBX/HP1-gamma expression, suggesting that CBX/HP1-gamma expression may be independent of EGFR downstream signaling. CONCLUSION: We report a significant upregulation of CBX3/HP1-gamma in NSCLC patients, and also a possible relationship between CBX3/HP1-gamma expression and EGFR mutation.