Imidacloprid is a neonicotinoid insecticide that is effective against house fly, Musca domestica L., which is a major pest with the ability to develop resistance to insecticides. In the present study, we investigated the inheritance mode, the cross-resistance pattern and the mechanisms of resistance to imidacloprid. A near-isogenic house fly line (N-IRS) with 78-fold resistance to imidacloprid was used to demonstrate the mode of inheritance. The overlapping confidence limits of LC50 values and the slopes of the log concentration-probit lines between the reciprocal F1 and F1’ progenies suggest that imidacloprid resistance is inherited autosomally in the house fly. There was incomplete dominant inheritance in the F1 and F1’ progenies, based on dominance values of 0.77 and 0.75, respectively. A monogenic inheritance model revealed that imidacloprid resistance is governed by more than one factor. Compared to the field strain (CFD), the N-IRS strain developed more cross-resistance to chlorfenapyr and no cross-resistance to chlorpyrifos and acetamiprid, but showed negative cross-resistance to beta-cypermethrin and azamethiphos. Three synergists, diethyl malate (DEM), s,s,s-tributylphosphorotrithioate (DEF), and piperonyl butoxide (PBO), showed significant synergism against to imidacloprid (4.55-, 4.46- and 3.34-fold respectively) in the N-IRS strain. However, both DEM and PBO had no synergism and DEF only exhibited slight synergism in the CSS strain. The activities of carboxylesterase (CarE), glutathione S-transferases (GSTs) and cytochrome P450 in the N-IRS strain were significantly higher than in the CSS strain. But similar synergistic potential of DEF to imidacloprid between the CSS and N-IRS strain suggested that GSTs and cytochrome P450 played much more important role than esterase for the N-IRS strain resistance to imidacloprid. These results should be helpful for developing an improved management strategy to delay the development of imidacloprid resistance in house fly.

Propoxur, a carbamate insecticide, has been used worldwide for the control of house flies (Musca domestica L.) for many decades. Resistance levels to propoxur have been detected in field populations of house flies in many parts of the world, including China. In this study, a near-isogenic house fly line (N-PRR) resistant to propoxur was used to determine the mode of inheritance. Bioassay results showed no significant differences in LD50 values or in the slope of log dose-probit lines between the reciprocal F1 and F1’ progenies, and the degree of dominance (D) was more than −1 and less than 0. Chi-square analysis of the responses of self-bred (F2, F2’) and backcross progenies (BC1, BC2, BC1’, and BC2’) indicated that a single gene was responsible for resistance. Propoxur resistance in the N-PRR strain of house fly was inherited as a single, major, autosomal, and incompletely recessive factor. These results should be useful to reveal the mode of inheritance and the development trend of propoxur resistance and develop a systematic strategy for the resistance management in house flies.

Two unique housefly strains, PSS and N-PRS (near-isogenic line with the PSS), were used to clarify the mechanisms associated with propoxur resistance in the housefly, Musca domestica. The propoxurselected resistant (N-PRS) strain exhibited >1035-fold resistance to propoxur and 1.70-, 12.06-, 4.28-, 57.76-, and 57.54-fold cross-resistance to beta-cypermethrin, deltamethrin, bifenthrin, phoxim, and azamethiphos, respectively, compared to the susceptible (PSS) strain. We purified acetylcholinesterase (AChE) from the N-PRS and PSS strains using a procainamide affinity column and characterized the AChE. The sensitivity of AChE to propoxur based on the bimolecular rate constant (K i) was approximately 100-fold higher in the PSS strain compared to the N-PRS strain. The cDNA encoding Mdace from both the N-PRS strain and the PSS strain were cloned and sequenced using RT-PCR. The cDNA was 2073 nucleotides long and encoded a protein of 691 amino acids. A total of four single nucleotide polymorphisms (SNPs), I162M, V260L, G342A, and F407Y, were present in the region of the active site of AChE from the N-PRS strain. The transcription level and DNA copy number of Mdace were significantly higher in the resistant strain than in the susceptible strain. These results indicated that mutations combined with the up-regulation of Mdace might be essential in the housefly resistance to propoxur.

Increasing evidence has demonstrated that high metastasis-associated in colon cancer-1 (MACC1) level is tightly associated with the development, progression, and poor prognosis of a variety of tumors. However, the relationship between MACC1 and the occurrence, development, and progression of osteosarcoma (OS) remains to be clarified. To facilitate and deepen the understanding of the associations of MACC1 with the development and progression of OS, in the current study, we detected the expressions of MACC1 mRNA and protein, and investigated the relationship between MACC1 expression and prognosis of the patients with OS. Our findings demonstrated that expressions of MACC1 mRNA and protein in OS tissues were significantly higher than those in paired normal bone tissues (P < 0.05). Additionally, the level of MACC1 mRNA in the patients with higher clinical stage and distant metastasis was markedly higher than those with lower clinical stage and without metastasis (P < 0.05). Furthermore, high MACC1 level was closely correlated with clinical stage and distant metastasis (P < 0.05), but not related to the patients' age, gender, tumor size, and anatomical location (P > 0.05). Stepwise investigation revealed that survival time of the patients with high MACC1 level was obviously lower than that with low MACC1 level (P < 0.05). Collectively, our data suggest that MACC1 may play important roles in the development and progression of OS, and thus may be considered as a novel molecular target for therapy of the patients with OS.

Two unique housefly strains, MSS and N-MRS, were selected and used to clarify mechanisms of sex-associated malathion resistance in the housefly, Musca domestica. Compared with the lab-susceptible CSS strain, susceptible females and resistant males were observed in the malathion-susceptible MSS strain, while the malathion-resistant near-isogenic line, N-MRS, achieved similar resistance level between genders. Significant synergistic effect of the esterase-inhibitor DEF on resistant houseflies pointed to the important involvement of esterase in this specific malathion resistance. Examination of the carboxylesterase gene MdαE7 in malathion resistant housefly populations found seven, non-synonymous SNP mutations (Ser250-Thr, Trp251-Ser, Met303-Ile, Leu354-Phe, Ser357-Leu, Trp378-Arg and Ser383-Thr), not found in susceptible houseflies, revealing a strong correlation between these mutations and the development of malathion resistance. Further genetic analysis conducted with bioassays by topical application and nucleotide polymorphism detection provided a first line of molecular evidence for a linkage between a male-determining factor and MdαE7 gene in the MSS and N-MRS males. This linkage results in a much higher level of malathion resistance for males than females in the MSS strain. Lastly, quantitative real-time PCR showed that MdαE7 was over expressed in the resistant strain due to the increased transcription level of mRNA rather than gene duplication.

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Background. Periodontitis is a kind of chronic infectious disease, affecting the health of billions of people. In recent years, a number of studies have shown that multiple immune gene polymorphisms are associated with the susceptibility to periodontitis, among which TLR-2 plays a critical role in periodontitis. But most of the studies reported TLR-2 gene polymorphism and susceptibility to periodontitis are not consistent. Therefore, we included all eligible studies in our study for further meta-analysis. Methods. We used electronic databases, including CNKI, PubMed, EMBASE, and Web of Science databases, and relevant research published through June, 2020. Selecting studies involved case-control trials. For all eligibility studies, odds ratios (ORs) and 95% confidence intervals (95% CI) are provided or can be calculated from the study data. The size of the combined effect was calculated using STATA 15.0. Results. Our meta-analysis included 14 articles representing 18 case-control studies with a total of 3873 cases and 3438 control subjects. Significant association was found between periodontitis and TLR-2 rs1898830 polymorphism under the allelic model (A allele vs. G allele: p=0.014, OR=1.208, 95% CI: 1.039-1.406), recessive model (GG vs. GA+AA: p=0.028, OR=0.755, 95% CI: 0.588-0.970), and codominant model (GG VS. AA: p=0.014, OR=0.681, 95% CI: 0.501-0.925). In subgroup analysis, TLR-2 rs5743708 polymorphism was associated with periodontitis risk in Asians under an allelic model (G allele vs. A allele: p=0.017, OR=12.064, 95% CI: 1.570-92.688), dominant model (GA+AA vs.GG: p=0.016, OR=0.08, 95% CI: 0.010-0.620), and codominant model (GA VS. GG: p=0.016, OR=1.026, 95% CI: 0.821-1.282). Conclusion. The TLR-2 rs1898830, rs5743708 polymorphism may be associated with susceptibility to periodontitis. In the future, genome-wide approaches and large-scale, multiethnic case-control trials are still needed.

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