Silence of Aminopeptidase N 2 gene reveals the trade-offs for acquiring Cry1Ac resistance in Plutella xylostella.

Bacillus thuringiensis (Bt) is widely used as a biopesticide worldwide. To date, at least eight pest species have been found to be resistant to Bt in the field. As the first pest that was reported having resistance to Bt in the field, considerable research has been done on the mechanisms of Bt resistance in Plutella xylostella. However, whether the acquisition of Bt resistance by P. xylostella comes at a fitness cost is also a valuable question. In this study, Aminopeptidase-N 2 (APN2), a Cry toxin receptor gene of P. xylostella, was knocked down by RNA interference, resulting in improved resistance to Cry1Ac. It was also found that larval mortality of APN2 knockdown P. xylostella was significantly higher than that of the control, while the pupation rate, pupal weight, eclosion rate, fecundity (egg/female), hatchability, and female adult longevity were significantly lower in APN2 knockdown P. xylostella than in the control. These results illustrate that if Cry1Ac resistance was obtained only through the reduction of APN2 expression, P. xylostella would need to incur some fitness costs for it.

Effects of Fruit Sizes of Two Camellia Trees on the Larval Sizes of Curculio styracis (Roelofs, 1875): Testing the Endoparasitoid Body Size Hypothesis.

The endoparasitoid body size hypothesis suggests that the size of larvae that develop in a single host should be subject to a trade-off: larger size could lead to increase overall fitness but could simultaneously increase the risk of resource depletion and starvation, resulting in a body size just below the host holding capacity. However, this hypothesis has not been rigorously tested using mathematical models thus far. The camellia weevil, C.styracis (Coleoptera: Curculionidae), is a notorious pest attacking fruits of Camellia oleifera Abel. and C. meiocarpa Hu., in which the larvae develop within a single fruit and larval development is limited by the available food resources. We developed a feasible method to test this hypothesis. First, five models were used to describe the relationship between larval mass and host size. Then, the minimum fruit threshold that had to be met for ad libitum larval development and the corresponding larval size (Wa) of this threshold were calculated based on the characteristics of the optimal model. Finally, the difference between the measured larval size and the predicted larval size (Wa) was determined. The results showed that (1) the data were better described by a logistic function than any other equation; (2) larval size in both host plants increased with increasing fruit size until leveling off when the fruits were large enough to allow unconstrained larval development; (3) larval size remained just below the host-fruit holding capacity, as there was no difference between the measured and predicted larval sizes (Wa); and (4) larvae developed in host plant with larger fruits had a larger size. These results confirmed the endoparasitoid body size hypothesis.

The effect of hepatitis B virus on T lymphocyte and its subsets in chronic hepatitis B patients in different ALT stages: A new concept ALT in HBV infection.

The aim of the present study was to explore the effect of hepatitis B virus on T lymphocyte and its subsets in different ALT states, and elucidate the immunological mechanism of ALT basing antiviral therapy for hepatitis B. 363 chronic hepatitis B patients were selected as the study subjects. According to ALT abnormalities, the patients were divided into three study groups. ALT normal group 131 cases, normal≦ ALT < 2 times of upper limit group 110 cases, ALT ≥ 2 times of upper limit group 122 cases. Entecavir was given to the ALT ≥ 2 times of upper limit group patients and followed up for 24 weeks. The hepatitis B antigen antibody parameters were measured by chemiluminescence immunoassay analyzer, the liver function parameters were measured by automatic biochemical analyzer, the hepatitis B virus load were measured by quantitative PCR analyzer, T lymphocytes were detected by flow cytometry, the level of IL-2, IFN-γ, IL-4 and IL-10 were detected by enzyme-linked immunosorbent assay. Detecting the influence of different hepatitis B viru loads in different groups on immunological indexes, and the virological and immunological indexes changes in before and after antiviral therapy patients. In the ALT normal group, different virus load hepatitis B virus had minor effect on T lymphocytes and their subsets (P > 0.05). In the ALT ≥ double upper limit of normal group. with the virus load increased, The total number of T lymphocytes, CD3+ CD4 + T lymphocytes decreased, (P < 0.05)CD3+ CD8 + T lymphocytes increased(P < 0.05). With the virus load increased the cytokines IL-2, IFN-γ which reflect the Th1 lymphocytes increased(P < 0.05), the cytokines IL-4、IL-10 which reflect the Th2 lymphocytes decreased(P < 0.05). Before and after 24 weeks of entecavir treatment, the patient's HBV-DNA decreased significantly(P < 0.05) and the body's immune function improved significantly. (P < 0.05)The influence of hepatitis B virus on immune function is different in different ALT states. Therefore, the scientific significance of ALT grouping in the hepatitis B treatment can be clarified from the immunological point.

Reduced Expression of a Novel Midgut Trypsin Gene Involved in Protoxin Activation Correlates with Cry1Ac Resistance in a Laboratory-Selected Strain of Plutella xylostella (L.).

Bacillus thuringiensis (Bt) produce diverse insecticidal proteins to kill insect pests. Nevertheless, evolution of resistance to Bt toxins hampers the sustainable use of this technology. Previously, we identified down-regulation of a trypsin-like serine protease gene PxTryp_SPc1 in the midgut transcriptome and RNA-Seq data of a laboratory-selected Cry1Ac-resistant Plutella xylostella strain, SZ-R. We show here that reduced PxTryp_SPc1 expression significantly reduced caseinolytic and trypsin protease activities affecting Cry1Ac protoxin activation, thereby conferring higher resistance to Cry1Ac protoxin than activated toxin in SZ-R strain. Herein, the full-length cDNA sequence of PxTryp_SPc1 gene was cloned, and we found that it was mainly expressed in midgut tissue in all larval instars. Subsequently, we confirmed that the PxTryp_SPc1 gene was significantly decreased in SZ-R larval midgut and was further reduced when selected with high dose of Cry1Ac protoxin. Moreover, down-regulation of the PxTryp_SPc1 gene was genetically linked to resistance to Cry1Ac in the SZ-R strain. Finally, RNAi-mediated silencing of PxTryp_SPc1 gene expression decreased larval susceptibility to Cry1Ac protoxin in the susceptible DBM1Ac-S strain, supporting that low expression of PxTryp_SPc1 gene is involved in Cry1Ac resistance in P. xylostella. These findings contribute to understanding the role of midgut proteases in the mechanisms underlying insect resistance to Bt toxins.

Characterization of immune-related PGRP gene expression and phenoloxidase activity in Cry1Ac-susceptible and -resistant Plutella xylostella (L.).

Peptidoglycan recognition proteins (PGRPs) are important recognition receptors which play a critical role in signal identification and transmission in Toll or immune deficiency (IMD) pathways, particularly when pathogens evade and circumvent reactive oxygen species. Antimicrobial peptides (AMPs) synthesis can be activated by these signals to further eliminate pathogens. In this study, we cloned and characterized three different PGRP genes in Plutella xylostella strains, DBM1Ac-S, DBM1Ac-R and a field strain (DBMF). The results showed that PGRP1 belongs to the PGRP-SA family, PGRP2 to PGRP-LB, and PGRP3 to PGRP-LF. Moreover, PGRP1 expressed the highest transcript level, followed by PGRP3 and PGRP2, in two tissues including the gut and the larval carcass tissues of the DBM1Ac-S strain. Furthermore, altered expression levels of PGRP1-3 genes were detected in both gut and carcass tissues. Moreover, the DBM1Ac-R strain had the highest phenol oxidase (PO) activity among these three strains. The characterization of PGRP gene expression and PO activity in DBM1Ac-S, DBM1Ac-R and DBM-F provides insights into their important physiological roles in the immune system of P. xylostella exposed to Bt Cry1Ac toxin.

Inhibitors of PARP-1 exert inhibitory effects on the biological characteristics of hepatocellular carcinoma cells in vitro.

It has been confirmed that the inhibitors of poly ADP-ribose polymerF(^9ase­1 (PARP­1) can inhibit the proliferation, apoptosis and invasion of tumor cells. However, the effects of inhibitors of PARP­1 on hepatocellular carcinoma remain to be elucidated. The aim of the present study was to investigate the effect of three types of PARP­1 inhibitor on the proliferation, apoptosis and migration of hepatocellular carcinoma in vitro. An MTT assay was performed to detect the proliferation of HepG2 cells following treatment with the PARP­1 inhibitors, AG014699, BSI­201 and AZD­2281. Flow cytometry was used to detect the apoptosis of HepG2 cells, Western blot analysis was used to detect the protein expression of Casepase­3, Casepase­8, B­cell lymphoma 2 (Bcl­2)­associated X protein (Bax), Bcl­2, phosphatase and tensin homolog (PTEN), tissue inhibitor of metalloproteinase (TIMP) 3 and matrix metalloprotease (MMP) 3. A Transwell assay was performed to detect the migration of HepG2 cells. The results showed that AG014699, BSI­201 and AZD­2281 had an inhibitory effect on the proliferation of HepG2 cells in a time­ and concentration­dependent manner. AG014699 at concentrations of 10, 30 and 50 µmol/l, and BSI­201 at concentrations of 20, 40 and 60 µmol/l induced the apoptosis of HepG2 cells, and the apoptotic rates were particularly high at 48 h (31, vs. 0.01%; P<0.01 and 24.12, vs. 0.03%, respectively; P<0.01). The protein expression levels of Caspase 3, Caspase 8, Bax, PTEN and TIMP 3 increased with increasing drug concentrations, whereas the protein levels of Bcl­2 and MMP3 decreased with increasing drug concentrations, and were significantly different compared with those in the control group (P<0.01). In conclusion, AG014699, BSI­201 and AZD­2281 inhibitors of PARP­1 significantly inhibited the proliferation of HepG2 cells, however, AG014699 and BSI­201 demonstrated more sensitivity, induced apoptosis and inhibited migration of the hepatocellular carcinoma cells, which may be associated with alterations of the apoptosis signaling pathway and the expression of proteins associated with migration.

Dynamic expression of genes encoding subunits of inward rectifier potassium (Kir) channels in the yellow fever mosquito Aedes aegypti.

Inward rectifier potassium (Kir) channels play fundamental roles in neuromuscular, epithelial, and endocrine function in mammals. Recent research in insects suggests that Kir channels play critical roles in the development, immune function, and excretory physiology of fruit flies and/or mosquitoes. Moreover, our group has demonstrated that mosquito Kir channels may serve as valuable targets for the development of novel insecticides. Here we characterize the molecular expression of 5 mRNAs encoding Kir channel subunits in the yellow fever mosquito, Aedes aegypti: Kir1, Kir2A-c, Kir2B, Kir2B', and Kir3. We demonstrate that 1) Kir mRNA expression is dynamic in whole mosquitoes, Malpighian tubules, and the midgut during development from 4th instar larvae to adult females, 2) Kir2B and Kir3 mRNA levels are reduced in 4th instar larvae when reared in water containing an elevated concentration (50mM) of KCl, but not NaCl, and 3) Kir mRNAs are differentially expressed in the Malpighian tubules, midgut, and ovaries within 24h after blood feeding. Furthermore, we provide the first characterization of Kir mRNA expression in the anal papillae of 4th instar larval mosquitoes, which indicates that Kir2A-c is the most abundant. Altogether, the data provide the first comprehensive characterization of Kir mRNA expression in Ae. aegypti and offer insights into the putative physiological roles of Kir subunits in this important disease vector.

Antagonizing programmed death-1 and programmed death ligand-1 as a therapeutic approach for gastric cancer.

Malignant tumor cells are equipped with mechanisms that can help them escape the surveillance by host immune system. Immune checkpoint molecules can transduce coinhibitory signals to immunocompetent cells and exert immunosuppressive roles in antitumor immunity. Programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) are the two important checkpoint molecules with great potential in targeted cancer therapy. Several antibodies targeting PD-1 and PD-L1 have been approved for clinical use. In this review, we focus on the recent development of targeting PD-1 and PD-L1 in gastric cancer (GC) therapy.

Effects of the suppression of lactate dehydrogenase A on the growth and invasion of human gastric cancer cells.

Lactate dehydrogenase A (LDH-A), which regulates glycolytic flux by catalyzing pyruvate to lactate in the cytoplasm, is believed to be one of the highly attractive therapeutic targets for cancers. Firstly, we detected the expression of LDH-A in gastric cancer (GC) cells. LDH-A inhibitor oxamate was then used to suppress the LDH-A activity in GC cells. Cell proliferation, lactic acid production, Transwell migration assay and apoptosis were assessed, respectively. The results showed that inhibition of LDH-A by oxamate decreased the lactate production. In the presence of glucose, oxamate inhibited cell proliferation in a dose-dependent manner. Flow cytometry assay further confirmed a pro-apoptotic effect of oxamate, and this was likely through increased expression of Bax, activated caspase-3, and decreased expression of Bcl-2. Therefore, we believe that oxamate inhibits cell growth, suppresses tumor invasion, and induces apoptosis in GC cells. LDH-A may be a potential therapeutic target for GC.

Tissue-specific transcriptome profiling of Plutella xylostella third instar larval midgut.

The larval midgut of diamondback moth, Plutella xylostella, is a dynamic tissue that interfaces with a diverse array of physiological and toxicological processes, including nutrient digestion and allocation, xenobiotic detoxification, innate and adaptive immune response, and pathogen defense. Despite its enormous agricultural importance, the genomic resources for P. xylostella are surprisingly scarce. In this study, a Bt resistant P. xylostella strain was subjected to the in-depth transcriptome analysis to identify genes and gene networks putatively involved in various physiological and toxicological processes in the P. xylostella larval midgut. Using Illumina deep sequencing, we obtained roughly 40 million reads containing approximately 3.6 gigabases of sequence data. De novo assembly generated 63,312 ESTs with an average read length of 416 bp, and approximately half of the P. xylostella sequences (45.4%, 28,768) showed similarity to the non-redundant database in GenBank with a cut-off E-value below 10(-5). Among them, 11,092 unigenes were assigned to one or multiple GO terms and 16,732 unigenes were assigned to 226 specific pathways. In-depth analysis identified genes putatively involved in insecticide resistance, nutrient digestion, and innate immune defense. Besides conventional detoxification enzymes and insecticide targets, novel genes, including 28 chymotrypsins and 53 ABC transporters, have been uncovered in the P. xylostella larval midgut transcriptome; which are potentially linked to the Bt toxicity and resistance. Furthermore, an unexpectedly high number of ESTs, including 46 serpins and 7 lysozymes, were predicted to be involved in the immune defense.As the first tissue-specific transcriptome analysis of P. xylostella, this study sheds light on the molecular understanding of insecticide resistance, especially Bt resistance in an agriculturally important insect pest, and lays the foundation for future functional genomics research. In addition, current sequencing effort greatly enriched the existing P. xylostella EST database, and makes RNAseq a viable option in the future genomic analysis.

Determining the involvement of two aminopeptidase Ns in the resistance of Plutella xylostella to the Bt toxin Cry1Ac: cloning and study of in vitro function.

The cloning, expression in vitro, and characterization of two aminopeptidase Ns (APN5s and APN2s) isolated from the midgut of Cry1Ac-resistant (R) and susceptible (S) strains of Plutella xylostella larvae are presented in this paper. The deduced amino acid sequences of APN5s included C-terminal GPI-modification sites, the gluzincin aminopeptidase motif GATEN, and three N-glycosylated sites; those of APN2s had no GPI-modification sites, had gluzincin aminopeptidase motif GAMEN, and had four N-glycosylated sites. O-glycosylated sites were not predicted for either APN. Because APN2R and APN2S cDNAs contained the same nucleotides, only full-length cDNAs encoding APN5R and APN5S were expressed in Trichoplusia ni cells. Far-Western blotting showed that the expressed receptor APN5 bound to the Cry1Ac toxin. An enzyme-specific activity experiment also showed that APN5 genes were expressed in T. ni cells. ELISA revealed no differences in the binding of expression proteins from the resistant and susceptible strain with Cry1Ac.