Overexpression of PxαE14 Contributing to Detoxification of Multiple Insecticides in Plutella xylostella (L.).

The diamondback moth, Plutella xylostella (L.), has evolved with varying degrees of resistance to almost all major classes of insecticides and has become the most resistant pest worldwide. The multiresistance to different types of insecticides has been frequently reported in P. xylostella, but little is known about the mechanism. In this study, a carboxylesterase (CarE) gene, PxαE14, was found significantly overexpressed in a field-evolved multiresistant P. xylostella population and can be dramatically induced by eight of nine tested insecticides. Results of the real-time quantitative polymerase chain reaction (RT-qPCR) showed that PxαE14 was predominantly expressed in the midgut and malpighian tubule of larvae. Knockdown of PxαE14 dramatically increased the susceptibility of the larvae to ß-cypermethrin, bifenthrin, chlorpyrifos, fenvalerate, malathion, and phoxim, while overexpression of PxαE14 in Drosophila melanogaster increased the tolerance of the fruit flies to these insecticides obviously. More importantly, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay showed that the recombinant PxαE14 expressed in Escherichia coli exhibited metabolic activity against the six insecticides. The homology modeling, molecular docking, and molecular dynamics simulation analyses showed that these six insecticides could stably bind to PxαE14. Taken together, these results demonstrate that constitutive and inductive overexpression of PxαE14 contributes to detoxification of multiple insecticides involved in multiresistance in P. xylostella. Our findings provide evidence for understanding the molecular mechanisms underlying the multiresistance in insect pests.

Treatment of old acetabular posterior wall fracture with 3D printing combined with composite plate internal fixation / 中国骨伤

OBJECTIVE@#To explore the application value and clinical effect of three-dimensional printing combined with composite plate internal fixation in the treatment of old acetabular posterior wall fracture.@*METHODS@#From May 2010 to October 2016, Mimics 19.0 software was used to plan preoperatively according to a 1:1 print pelvic 3D model. At the same time, 23 patients with old acetabular posterior wall fractures were treated with combined plate internal fixation, including 15 males and 8 females, aged 20 to 63 (43.0±5.1) years old, and the time from injury to operation was 23 to 101(47.0±10.5) days. According to Letournel-Judet classification, 11 cases were posterior wall fracture, 7 cases were transverse with posterior wall fracture, and 5 cases were posterior column with posterior wall fracture. All patients were treated with single Kocher-Langenbeck approach combined plate internal fixation, and the evaluation indexes were recorded during operation, after operation and during follow-up.@*RESULTS@#The operation time of 23 patients was (113.5±11.5) min, bleeding was (550.0±104.7) ml and fluoroscopy was (12.7±0.8) s. Matta radiographic reduction criteria were used: excellent in 14 cases, good in 7 cases and poor in 2 cases; 23 patients were followed up for 10 to 24 (16.0±5.6) months. The hip function was evaluated according to the modified Merle d'Aubingne and Postal scoring system at the last follow-up: excellent in 11 cases, good in 8 cases, fair in 3 cases and poor in 1 case. There were 3 cases of traumatic arthritis, 1 case of femoral head necrosis, 2 cases of heterotopic ossification and 5 cases of sciatic nerve irritation.@*CONCLUSIONS@#3D printing technique is an effective and fast method for the treatment of old acetabular posterior wall fractures. In addition, the printing model can provide three-dimensional morphological structure for the operator, combined with preoperative simulation, facilitate intraoperative reduction, and effectively improve the efficiency of surgery.

Different chitin synthase genes are required for various developmental and plant infection processes in the rice blast fungus Magnaporthe oryzae.

Chitin is a major component of fungal cell wall and is synthesized by chitin synthases (Chs). Plant pathogenic fungi normally have multiple chitin synthase genes. To determine their roles in development and pathogenesis, we functionally characterized all seven CHS genes in Magnaporthe oryzae. Three of them, CHS1, CHS6, and CHS7, were found to be important for plant infection. While the chs6 mutant was non-pathogenic, the chs1 and chs7 mutants were significantly reduced in virulence. CHS1 plays a specific role in conidiogenesis, an essential step for natural infection cycle. Most of chs1 conidia had no septum and spore tip mucilage. The chs6 mutant was reduced in hyphal growth and conidiation. It failed to penetrate and grow invasively in plant cells. The two MMD-containing chitin synthase genes, CHS5 and CHS6, have a similar expression pattern. Although deletion of CHS5 had no detectable phenotype, the chs5 chs6 double mutant had more severe defects than the chs6 mutant, indicating that they may have overlapping functions in maintaining polarized growth in vegetative and invasive hyphae. Unlike the other CHS genes, CHS7 has a unique function in appressorium formation. Although it was blocked in appressorium formation by germ tubes on artificial hydrophobic surfaces, the chs7 mutant still produced melanized appressoria by hyphal tips or on plant surfaces, indicating that chitin synthase genes have distinct impacts on appressorium formation by hyphal tip and germ tube. The chs7 mutant also was defective in appressorium penetration and invasive growth. Overall, our results indicate that individual CHS genes play diverse roles in hyphal growth, conidiogenesis, appressorium development, and pathogenesis in M. oryzae, and provided potential new leads in the control of this devastating pathogen by targeting specific chitin synthases.