BackgroundBooklice (psocids) in the genus Liposcelis (Psocoptera: Liposcelididae) are a group of important storage pests, found in libraries, grain storages, and food-processing facilities. Booklice are able to survive under heat treatment and typically possess high resistance to common fumigant insecticides, hence posing a threat to storage security worldwide.ResultsWe assembled the genome of the booklouse, L. brunnea, the first genome reported in Psocoptera, using PacBio long-read sequencing, Illumina sequencing, and chromatin conformation capture (Hi-C) methods. After assembly, polishing, haplotype purging, and Hi-C scaffolding, we obtained 9 linkage groups (174.1 Mb in total) ranging from 12.1 Mb to 27.6 Mb (N50: 19.7 Mb), with the BUSCO completeness at 98.9%. In total, 15,543 genes were predicted by the Maker pipeline. Gene family analyses indicated the sensing-related gene families (OBP and OR) and the resistance-related gene families (ABC, EST, GST, UGT, and P450) expanded significantly in L. brunnea compared with those of their closest relatives (2 parasitic lice). Based on transcriptomic analysis, we found that the CYP4 subfamily from the P450 gene family functioned during phosphine fumigation; HSP genes, particularly those from the HSP70 subfamily, were upregulated significantly under high temperatures.ConclusionsWe present a chromosome-level genome assembly of L. brunnea, the first genome reported for the order Psocoptera. Our analyses provide new insights into the gene family evolution of the louse clade and the transcriptomic responses of booklice to environmental stresses.

Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae) is a booklouse pest that is a threat to commodity storage security worldwide. Accurate and sensitive methods of L. bostrychophila on-site identification are essential prerequisites for its effective management. Evidence suggests that L. bostrychophila contains 3 intraspecific biotypes that are morphologically indistinguishable but can be discriminated at the level of mitochondrial genome organization and sequences. The traditional molecular identification methods, such as DNA barcoding and PCR-RFLP, are instrumentally demanding and time-consuming, limiting the application of the identification in the field. Therefore, this study developed a new CRISPR/Cas12a-based visual nucleic acid system based on the mitochondrial gene coding for NADH dehydrogenase subunit 2 (nad2), combined with recombinase polymerase amplification (RPA) to accurately identify L. bostrychophila from 4 other common stored-product booklice, and also differentiate 3 biotypes of this species at the same time. The entire identification process could be completed at 37 °C within 20 min with high sensitivity. The system could stably detect at least 1 ng/μl of DNA template. The green fluorescence signal produced by the trans-cleaving of the single-stranded DNA reporter could be observed by the naked eye under blue light. Additionally, the suggested system combined with the crude DNA extraction method to extract DNA rapidly, enabled identification of all developmental stages of L. bostrychophila. With crude DNA, this novel diagnostic system successfully identified an unknown booklouse by holding the reaction tubes in the hand, thus can be considered as an accurate, rapid, highly sensitive, and instrument-flexible method for on-site visual identification of L. bostrychophila.

Background: Preeclampsia is an important clinical syndrome occurring during pregnancy. It shows genetic disposition, and the genetic risk has large ethnic heterogeneity. The study was designed to investigate the genetic risk of preeclampsia in Chinese pregnancies, and to apply it in early screening of the disease. Methods: We performed a genome-wide association study to screen candidate risk loci associated with preeclampsia in Chinese people, and validated them with an independent cohort of enlarged size. We also trained prediction models using the genotypes of newly identified risk loci to screen the pregnancies with high preeclampsia risk. Results: A segment in chromosome 6 covering HLA-DQB1, HLA-DRB5 and other immune-related genes shows the most significant association, and three loci in HLA-DRB5 were confirmed with an enlarged validation cohort. One of the validated loci, rs147440497, forms an amino acid change by the nucleotide polymorphism, which further causes a conformational change in the antigen-binding domain of HLA-DRB5 protein. With the genotypes of risk genetic loci and other demographic features, a machine-learning model was trained, which can predict Chinese preeclampsia pregnancies accurately, with a cross-validated recalling rate of 0.63 at a false positive rate of 8%. Conclusion: We identified a novel gene from maternal genome, HLA-DRB5, the polymorphism in which is associated with preeclampsia. The genotypes of risk SNP loci can also be used for prediction of preeclampsia risk in Chinese population accurately.