Trehalase Research Articles

Stress Response of Aphid Population Under Combined Stress of Cadmium and Lead and Its Effects on Development of Harmonia axyridis.

Heavy metal pollution is a serious global environmental issue. It threatens human and ecological health. Heavy metals can accumulate in the soil over extended periods and inevitably transfer through the food chain to herbivorous insects and their natural enemies, leading to various adverse effects. This study aimed to investigate the stress responses and biochemical metabolic changes of aphids and one of aphids' predators, ladybugs, under cadmium (Cd) and lead (Pb) stress by constructing a food chain of Vicia faba L., Megoura crassicauda, and Harmonia axyridis. The results showed that aphids and ladybugs had a notable accumulation of Cd2+ and Pb2+. Insects can adapt to heavy metal stress by regulating their energy metabolism pathways. Glycogen content in the first filial generation (F1) aphids decreased significantly, glucose content in the second filial generation (F2) to the fourth filial generation (F4) adult aphids significantly increased, and trehalose content in the F1 adult aphids increased significantly. Moreover, the relative expression levels of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) in the F1 adult aphids were significantly higher than those in the control group, and the expression levels of TPS genes in the second filial generation to the fifth filial generation (F2 to F5) aphids decreased, suggesting that insects can resist heavy metal stress by regulating trehalose metabolism. The fertility of female aphids in all treatment groups was reduced compared to the control group. Additionally, the relative expression level of vitellogenin (Vg) was down-regulated in all aphid generations except the F1 aphids. There was interaction between heavy metal concentration and aphid generation, and it significantly affected the number of aphids' offspring and the expression of the aphid Vg gene. The developmental duration of the ladybugs from the second to fourth instars was prolonged, and the weight decreased significantly from the prepupa to the adult stages. These results contribute to understanding the effects of Cd2+-Pb2+ accumulation on phytophagous insects and higher trophic levels' natural enemies, laying the foundation for protecting natural enemies and maintaining ecosystem stability.

The impact of three thioxothiazolidin compounds on trehalase activity and development of Spodoptera frugiperda larvae.

Trehalases (TREs), serving as crucial enzymes regulating trehalose and chitin metabolism in insects, represent prime targets for pest control strategies. We investigated the impact of three thioxothiazolidin compounds (1G, 2G, and 11G) on TRE activity and summarized their effects on the growth and development of Spodoptera frugiperda (Lepidoptera, Noctuidae). The experimental larvae of S. frugiperda were injected with the three thioxothiazolidin compounds (1G, 2G, and 11G), while the control group received an equivalent volume of 2% DMSO as a control. All three compounds had a strong effect on inhibiting TRE activity, significantly prolonging the pre-pupal development stage. However, compared with the 11G-treated group, the survival rate of larvae treated with 1G and 2G was significantly reduced by 31.11% and 27.78% respectively, while the occurrence of phenotypic abnormalities related to growth and development was higher. These results manifest that only the TRE inhibitors, 1G and 2G, modulate trehalose and chitin metabolism pathways of larvae, ultimately resulting in the failure molting and reduction of survival rates. Consequently, the thioxothiazolidin compounds, 1G and 2G, hold potential as environmentally friendly insecticides.

α,β-trehalose, an intracellular substance in resting cyst of colpodid ciliates as a key to environmental tolerances

α,α-trehalose is a well-known sugar that plays a key role in establishing tolerance to environmental stresses in many organisms, except unicellular eukaryotes. However, almost nothing is known about α,β-trehalose, including their synthesis, function, and even presence in living organisms. In this study, we identified α,β-trehalose in the resting cyst, a dormancy cell form characterized by extreme tolerance to environmental stresses, of the ciliated protist Colpoda cucullus, using high-performance liquid chromatography (HPLC), and a proton nuclear magnetic resonance (1H NMR). Gene expression analysis revealed that the expression of trehalose-6-phosphate synthase (TPS), glycosyltransferase (GT), alpha-amylase (AMY), and trehalose transporter 1 (TRET1), were up-regulated in encystment, while the expression of α-glucosidase 2 (AG2) and trehalase (TREH) was up-regulated in excystment. These results suggest that α,β-trehalose is synthesized during encystment process, while and contributes to extreme tolerances to environmental stressors, stored carbohydrates, and energy reserve during resting cyst and/or during excystment.

Impact of Three Thiazolidinone Compounds with Piperine Skeletons on Trehalase Activity and Development of Spodoptera frugiperda Larvae.

Trehalases (TREs) are pivotal enzymes involved in insect development and reproduction, making them prime targets for pest control. We investigated the inhibitory effect of three thiazolidinones with piperine skeletons (6a, 7b, and 7e) on TRE activity and assessed their impact on the growth and development of the fall armyworm (FAW), Spodoptera frugiperda. The compounds were injected into FAW larvae, while the control group was treated with 2% DMSO solvent. All three compounds effectively inhibited TRE activity, resulting in a significant extension of the pupal development stage. Moreover, the treated larvae exhibited significantly decreased survival rates and a higher incidence of abnormal phenotypes related to growth and development compared to the control group. These results suggest that these TRE inhibitors affect the molting of larvae by regulating the chitin metabolism pathway, ultimately reducing their survival rates. Consequently, these compounds hold potential as environmentally friendly insecticides.

Differential intestinal effects of water and foodborne exposures of nano-TiO2 in the mussel Mytilus coruscus under elevated temperature

With the wide use of nanomaterials in daily life, nano-titanium dioxide (nano-TiO2) presents potential ecological risks to marine ecosystems, which can be exacerbated by ocean warming (OW). However, most previous studies have only centered around waterborne exposure, while there is a scarcity of studies concentrating on the impact of trophic transfer exposure on organisms. We investigated the differences in toxic effects of 100 μg/L nano-TiO2 on mussels via two pathways (waterborne and foodborne) under normal (24 °C) and warming (28 °C) conditions. Single nano-TiO2 exposure (waterborne and foodborne) elevated the superoxide dismutase (SOD) and catalase (CAT) activities as well as the content of glutathione (GSH), indicating activated antioxidatant response in the intestine. However, depressed antioxidant enzymes and accumulated peroxide products (LPO and protein carbonyl content, PCC) demonstrated that warming in combination with nano-TiO2 broke the prooxidant-antioxidant homeostasis of mussels. Our findings also indicated that nano-TiO2 and high temperature exhibited adverse impacts on amylase (AMS), trypsin (PS), and trehalase (THL). Additionally, activated immune function (lysozyme) comes at the cost of energy expenditure of protein (decreased protein concentration). The hydrodynamic diameter of nano-TiO2 at 24 °C (1693–2261 nm) was lower than that at 28 °C (2666–3086 nm). Bioaccumulation results (range from 0.022 to 0.432 μg/g) suggested that foodborne induced higher Ti contents in intestine than waterborne. In general, the combined effects of nano-TiO2 and warming demonstrated a more pronounced extent of interactive effects and severe damage to antioxidant, digestive, and immune parameters in mussel intestine. The toxicological impact of nano-TiO2 was intensified through trophic transfer. The toxic effects of nano-TiO2 are non-negligible and can be exerted together through both water- and foodborne exposure routes, which deserves further investigation.

Identification and RNAi-based function analysis of trehalase family genes in Frankliniella occidentalis (Pergande).

Insects utilize trehalases (TREs) to regulate energy metabolism and chitin biosynthesis, which are essential for their growth, development, and reproduction. TREs can therefore be used as potential targets for future insecticide development. However, the roles of TREs in Frankliniella occidentalis (Pergande), a serious widespread agricultural pest, remain unclear. Three TRE genes were identified in F. occidentalis and cloned, and their functions were then investigated via feeding RNA interference (RNAi) and virus-induced gene silencing (VIGS) assays. The results showed that silencing FoTRE1-1 or FoTRE1-2 significantly decreased expression levels of FoGFAT, FoPGM, FoUAP, and FoCHS, which are members of the chitin biosynthesis pathway. Silencing FoTRE1-1 or FoTRE2 significantly down-regulated FoPFK and FoPK, which are members of the energy metabolism pathway. These changes resulted in 2-fold decreases in glucose and glycogen content, 2-fold increases in trehalose content, and 1.5- to 2.0-fold decreases in chitinase activity. Furthermore, knocking down FoTRE1-1 or FoTRE1-2 resulted in deformed nymphs and pupae as a result of hindered molting. The VIGS assay for the three FoTREs revealed that FoTRE1-1 or FoTRE2 caused shortened ovarioles, and reduced egg-laying and hatching rates. The results suggest that FoTRE1-1 and FoTRE1-2 play important roles in the growth and development of F. occidentalis, while FoTRE1-1 and FoTRE2 are essential for its reproduction. These three genes could be candidate targets for RNAi-based management and control of this destructive agricultural pest. © 2024 Society of Chemical Industry.

Exogenous GR24 Inhibits Strawberry Tillering by Affecting the Phytohormone Signaling and Sugar Metabolism Pathways

Tillering is an important part in strawberry growth, and strawberries can reproduce nutritionally through stolons to generate genetically stable offspring. However, excessive tillering during the fruit-growing stage can negatively impact fruit yield and quality. In this study, different concentrations of exogenous rac-GR24 (GR24) are used to treat the strawberry plants. It was found that GR24 effectively inhibited the sprouting of strawberry stolons, while promoting the growth of the stems and leaves. Among the treatments, the most effective concentration was found to be 5 μmol/L GR24. This treatment resulted in a decrease in the glucose content in the strawberry crowns and also caused changes in the contents of two endogenous phytohormones, gibberellic acid (GA3) and trans-zeatin riboside (tZR). Transcriptome data further suggested that exogenous GR24 may inhibit strawberry plant tillering by affecting various phytohormone signaling pathways and the sugar metabolism pathway. In 5 μmol/L GR24-treated plants, the expression level of type-B response regulator (B-ARR) was down-regulated and the expression level of CYTOKININ RESPONSE 1 (CRE1), histidine-containing phosphotransfer protein (AHP), and type-A response regulator (A-ARR) were up-regulated, suggesting the inhibition of the cytokinin (CTK) signaling pathway. The down-regulation of auxin (AUX) and auxin response factor (ARF), as well as the up-regulation of auxin/indole-3-acetic acid (AUX/IAA), led to the inhibition of the indole-3-acetic acid (IAA) signaling pathway. Additionally, the up-regulation of pyrabactin resistance 1/ pyrabactin resistance 1-like (PYR/PYL), non-fermenting 1-related protein kinase 2 (SnRK2), and ABRE binding factors (ABF) and the down-regulation of protein phosphatase 2C (PP2C) were observed in the up-regulated abscisic acid (ABA) signaling pathways. In the sugar metabolism pathway, the up-regulation of invertase (INV), hexokinase (HK), and fructokinase (FRK) and the down-regulation of trehalase (TREH) and beta-amylase (BMY) led to a decreased glucose synthesis and an increased glucose consumption. Therefore, GR24 can effectively inhibit strawberry plant tillering through these pathways, making it an effective reagent for tillering inhibition.

Trehalose-6-Phosphate Synthase Contributes to Rapid Cold Hardening in the Invasive Insect Lissorhoptrus oryzophilus (Coleoptera: Curculionidae) by Regulating Trehalose Metabolism.

Rapid cold hardening (RCH) is known to rapidly enhance the cold tolerance of insects. Trehalose has been demonstrated to be a cryoprotectant in Lissorhoptrus oryzophilus, an important invasive pest of rice in China. Trehalose synthesis mainly occurs through the Trehalose-6-phosphate synthase (TPS)/trehalose-6-phosphate phosphatase (TPP) pathway in insects. In this study, the TPS gene from L. oryzophilus (LoTPS) was cloned and characterized for the first time. Its expression and trehalose content changes elicited by RCH were investigated. Our results revealed that RCH not only increased the survival rate of adults but also upregulated the expression level of LoTPS and increased the trehalose content under low temperature. We hypothesized that upregulated LoTPS promoted trehalose synthesis and accumulation to protect adults from low-temperature damage. To further verify the function of the LoTPS gene, we employed RNA interference (RNAi) technology. Our findings showed that RCH efficiency disappeared and the survival rate did not increase when the adults were fed dsRNA of LoTPS. Additionally, inhibiting LoTPS expression resulted in no significant difference in trehalose content between the RCH and non-RCH treatments. Furthermore, the expression patterns of trehalose transporter (TRET) and trehalase (TRE) were also affected. Collectively, these results indicate the critical role of LoTPS in L. oryzophilus cold resistance after RCH induction. LoTPS can enhance survival ability by regulating trehalose metabolism. These findings contribute to further understanding the role of TPS in insect cold resistance and the invasiveness of L. oryzophilus. Moreover, RNAi of LoTPS opens up possibilities for novel control strategies against L. oryzophilus in the future.

Effects of exogenous trehalose on filling characteristics and sugar component content of wheat under high temperature stress during the filling period.

Taking the heat-sensitive wheat variety 'Fanmai 5' (FM5) and the heat-tolerant variety 'Huaimai 33' (HM33), which were screened out in the previous experiments, as experimental materials, we conducted a field experiment with passive heat-enhancing shelters to simulate post-flowering high-temperature environment (average temperature increase of 5.13 ℃) during 2021-2022. During the filling period, we analyzed the effects of exogenous trehalose (10, 15 and 20 mmol·L-1) on the filling characteristics and sugar fraction under high temperature, with no spraying at ordinary temperature as control (CK). The results showed that treating without spraying exogenous trehalose at high temperature (H) significantly reduced wheat grain yield and grain weight during the filling period, and spraying exogenous trehalose alleviated the reduction of grain yield and grain weight at the filling stage under high temperature stress. Compared with the H treatment, grain yield and grain weight of HM33 and FM5 wheat varie-ties increased by 3.5%, 6.7% and 4.2%, 5.4%, respectively. High temperature stress significantly increased the trehalose content and trehalase (THL) activity in flag leaves of both wheat varieties, and decreased the fructose and glucose contents. Spraying exogenous trehalose increased the contents of trehalose, fructose, and glucose in flag leaves, and decreased the trehalase activity in flag leaves compared with H treatment, which could improve the glucose metabolism capacity of wheat at filling stage. The increasing effect of FM5 was higher than that of HM33. High temperature stress significantly reduced starch content of flag leaves and grains, while spraying exogenous trehalose alleviated the decrease of starch content of flag leaves and grains under high temperature stress, which was profit able for the substance accumulation of wheat grains under high temperature stress. Under the conditions of this experiment, spraying 15 mmol·L-1 trehalose at flowering stage was the best treatment for the two wheat varieties.

The mechanism of polysaccharide synthesis of Sanghuangporus sanghuang based on multi-omic analyses and feedback inhibition

S. sanghuang polysaccharide has various biological roles in promoting human health, however, the underlying mechanism of polysaccharide synthesis in S. sanghuang remain elusive. In the present study, the molecular structure of novel polysaccharide in the mutant S. sanghuang strain A130 with high yield of polysaccharide was characterized. The critical genes/proteins and pathways involved in polysaccharide synthesis were investigated via comparative transcriptomic, proteomic, and integrative analysis between wildtype strain SH-1 and A130. An integrated analysis of transcriptomic and proteomic results was also performed to locate potential regulators in the production of polysaccharides. The genes of cellobiohydrolase1 (CBH1) and MutS Homolog 6 (MSH6) related to glycolysis/gluconeogenesis were differentially expressed between A130 and SH-1, suggesting the potential involvement of these genes in regulating the production of polysaccharide. Proteomic analysis revealed that the abundance of Tyrosinase (TYR) and Trehalase (TREH) were substantially different between A130 and SH-1. The potential involvement of TYR in polysaccharide production was confirmed by transcriptomic-proteomic integrated analysis. The biological role of TYR and TREH in polysaccharide production was further verified by feedback inhibition of kojic acid and validamycin A, respectively. Overall, our study provides critical insights for the polysaccharide synthesis and high yield of polysaccharide through genes/pathways regulating in S. sanghuang.

A survey of the genes encoding trehalose-metabolism enzymes in crustaceans

Abstract Trehalose is important in activity, development, and environmental-stress response, especially in invertebrates. It is mainly synthesized by trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP), and degraded by trehalase (TRE). In the present study, the tps, tpp, and tre were identified from various crustacean species and their phylogeny, structure, network, and transcriptome were analyzed. The tps and tpp are fused in crustaceans, accompanied with multi-copies of genes to improve the synthesis capacity of trehalose, and they may be formed by whole-genome duplication (WGD) and/or segmental duplications. Phylogenetic subgroups of enzymes in the same species may be due to the different lengths and distribution positions of domains. The protein with single TPP domain in the salmon louse, the copepod Lepeophtheirus salmonis (Krøyer, 1837), probably has a depoisoning effect. Structure analyses and location predictions showed that crustacean TRE possess an α-helix-rich structure with barrel core, and are membrane-bound, cytoplasmic, and secreted. Additionally, the non-acid TRE might not be adjusted by Ca2+ because there is no binding domain in crustaceans. Expression profiles of different tissues, developmental periods, and environmental-challenge responses, as well as genes of co-expression networks suggested that TPS (including TPP) and TRE might play important roles in physiological activities including development and environmental adaptation in crustaceans. Multi-copies of tre may enhance survival ability of copepods in diverse and sometimes harsh environments. Branchiopods, copepods, and the marine shrimp Penaeus vannamei Boone, 1931 are suspected to adopt possible acid TRE as a supplementary strategy in response to stress.

Bioinformatic analyses to uncover genes involved in trehalose metabolism in the polyploid sugarcane

Trehalose-6-phosphate (T6P) is an intermediate of trehalose biosynthesis that plays an essential role in plant metabolism and development. Here, we comprehensively analyzed sequences from enzymes of trehalose metabolism in sugarcane, one of the main crops used for bioenergy production. We identified protein domains, phylogeny, and in silico expression levels for all classes of enzymes. However, post-translational modifications and residues involved in catalysis and substrate binding were analyzed only in trehalose-6-phosphate synthase (TPS) sequences. We retrieved 71 putative full-length TPS, 93 trehalose-6-phosphate phosphatase (TPP), and 3 trehalase (TRE) of sugarcane, showing all their conserved domains, respectively. Putative TPS (Classes I and II) and TPP sugarcane sequences were categorized into well-known groups reported in the literature. We measured the expression levels of the sequences from one sugarcane leaf transcriptomic dataset. Furthermore, TPS Class I has specific N-glycosylation sites inserted in conserved motifs and carries catalytic and binding residues in its TPS domain. Some of these residues are mutated in TPS Class II members, which implies loss of enzyme activity. Our approach retrieved many homo(eo)logous sequences for genes involved in trehalose metabolism, paving the way to discover the role of T6P signaling in sugarcane.

Three Genes Related to Trehalose Metabolism Affect Sclerotial Development of Rhizoctonia solani AG-1 IA, Causal Agent of Rice Sheath Blight

Trehalose metabolism is related to the sclerotial development of Rhizoctonia solani AG-1 IA, the causal agent of rice sheath blight (RSB). Here, we further elucidated the functions of three genes Rstre, Rstps1 and Rstpp that encode three key enzymes trehalase (TRE), alpha, alpha-trehalose- phosphate synthase (TPS1) and trehalose 6-phosphate phosphatase (TPP) in the sclerotial development of R. solani AG-1 IA. Due to the lack of a stable genetic transformation system for R. solani, the heterologous expression of these three genes in Pichia pastoris GS115 was performed. The results showed that reactive oxygen species (ROS) contents and enzyme activities in R. solani decreased significantly in the treatments of the fermentation broths of Rstps1 and Rstpp transformants, and that in the treatment of the fermentation broth of Rstre transformant visibly increased. Furthermore, the fermentation broths of the transformants of all the three genes were added to potato dextrose agar (PDA) medium for the cultivation of R. solani, as a result, the dry weight of sclerotia in each PDA plate containing the fermentation broths of Rstps1 and Rstpp transformants significantly increased compared with the control, and that of Rstre transformant obviously decreased. Finally, 178 proteins were found to interact with RSTPS1, and 16 of them were associated with ROS. Taken together, the findings suggest that all these three genes related to trehalose metabolism play important roles in the sclerotial development of R. solani AG-1 IA, and can be used as new targets for the development of novel high-efficiency fungicides for the controlling of RSB.

Trehalose Alleviated Salt Stress in Tomato by Regulating ROS Metabolism, Photosynthesis, Osmolyte Synthesis, and Trehalose Metabolic Pathways.

Trehalose plays a critical role in plant response to salinity but the involved regulatory mechanisms remain obscure. Here, this study explored the mechanism of exogenous trehalose-induced salt tolerance in tomato plants by the hydroponic test method. Our results indicated that 10 mM trehalose displayed remarkable plant biomass by improving growth physiology, which were supported by the results of chlorophyll fluorescence and rapid light–response curve. In the salinity environment, trehalose + NaCl treatment could greatly inhibit the decrease of malondialdehyde level, and it increases the contents of other osmotic substances, carbohydrates, K+, and K+/Na+ ratio. Meanwhile, trehalose still had similar effects after recovery from salt stress. Furthermore, trehalose pretreatment promoted trehalose metabolism; significantly increased the enzymatic activity of the trehalose metabolic pathway, including trehalose-6-phosphate synthase (TPS), trehalose-6-phosphate phosphatase (TPP), and trehalase (TRE); and upregulated the expression of SlTPS1, SlTPS5, SlTPS7, SlTPPJ, SlTPPH, and SlTRE under saline conditions. However, the transcriptional levels of SlTPS1, SlTPS5, and SlTPS7 genes and the activity of TPS enzyme were reversed after recovery. In addition, we found that hydrogen peroxide (H2O2) and superoxide anion (O2−) were accumulated in tomato leaves because of salt stress, but these parameters were all recovered by foliar-applied trehalose, and its visualization degree was correspondingly reduced. Antioxidant enzyme activities (SOD, POD, and CAT) and related gene expression (SlCu/Zn-SOD, SlFe-SOD, SlMn-SOD, SlPOD, and SlCAT) in salt-stressed tomato leaves were also elevated by trehalose to counteract salt stress. Collectively, exogenous trehalose appeared to be the effective treatment in counteracting the negative effects of salt stress.

Separate immobilization of glucose oxidase and trehalase, and optimization of enzyme-carbon nanotube layers for the anode of enzymatic fuel cells utilizing trehalose

Insect cyborgs can be used as search robots in disaster areas and as environmental monitoring robots. In this study, we aimed to develop an anode for compact enzymatic fuel cells (EFCs) utilizing trehalose to power electronic devices implanted in such insects. Conventional trehalose-EFCs are fabricated by co-immobilization of glucose oxidase (GOx) and trehalase (TREH) on the surface of the anode. Here, we showed that current generation can be enhanced by separate immobilization of GOx and TREH using agarose. The effects of GOx-redox mediator layers, TREH loading, and the incorporation of single-walled carbon nanotubes (SWCNTs) on the performance of GOx-TREH anodes were investigated. The optimal arrangement of GOx-redox mediator layers with or without SWCNTs was determined. The highest oxidation current density (494 μA/cm2) was obtained at an electrode composed of three GOx-redox mediator layers and three GOx-redox mediator-SWCNTs layers, and agarose containing TREH. The bilirubin oxidase (BOD)-redox mediator layers and SWCNTs also influenced the performance of cathode. The highest reduction current intensity was obtained for the cathode with six BOD-redox mediator-SWCNTs layers. EFCs with the optimized anode and cathode showed a power density of ca. 15 μW/cm2 at a cell voltage of 0.3 V under a discharge current density of 50 μA/cm2.

Sublethal concentration of emamectin benzoate inhibits the growth of gypsy moth by inducing digestive dysfunction and nutrient metabolism disorder.

Gypsy moth (Lymantria dispar) is one of the most important pests in the world. Emamectin benzoate (EMB) is widely used in the control of agricultural and forestry pests. Here, we explored the sublethal effects of EMB on gypsy moths in order to better understand the toxicological mechanism of EMB. The sublethal concentration of EMB exposure significantly decreased the larvae body weight. To further explore the mechanism, indicators related to digestion and nutrient metabolism were detected. The results showed that EMB exposure caused midgut damage, reduced the activities of digestive enzymes and changed the content of sugar and amino acids. Moreover, the expression of insulin/phosphoinositide-3-kinase (PI3K)/forkhead box protein O (FoxO) pathway and sugar metabolism-related genes was abnormal. The expression of insulin receptor (InR), chico, PI3K, and protein kinase B (Akt) significantly reduced, and that of phosphatase and tensin homologue (PTEN) and FoxO increased. The expression of glycogen phosphorylase (GP) was upregulation and that of glycogen synthase (GS), trehalase (TRE) and trehalose-phosphate synthase (TPS) were downregulation. All results indicated that EMB inhibits the growth of gypsy moth by inducing midgut injury, digestive dysfunction and nutrient metabolism disorder. In addition, EMB caused midgut injury may be related to apoptosis or a collateral effect of the damage in other tissues, and more extensive and deeper research is still needed to investigate the detailed mechanism. Our finding strengthens the understanding of the sublethal effect of EMB, and provides a theoretical basis for the application of EMB in the prevention and control of gypsy moth.

RNA interference of trehalose-6-phosphate synthase and trehalase genes regulates chitin metabolism in two color morphs of Acyrthosiphon pisum Harris

Trehalose-6-phosphate synthase (TPS) and trehalase (TRE) directly regulate trehalose metabolism and indirectly regulate chitin metabolism in insects. Real-time quantitative PCR (RT-qPCR) and RNA interference (RNAi) were used to detect the expressions and functions of the ApTPS and ApTRE genes. Abnormal phenotypes were found after RNAi of ApTRE in the Acyrthosiphon pisum. The molting deformities were observed in two color morphs, while wing deformities were only observed in the red morphs. The RNAi of ApTPS significantly down-regulated the expression of chitin metabolism-related genes, UDP-N-acetyglucosamine pyrophosphorylase (ApUAP), chitin synthase 2 (Apchs-2), Chitinase 2, 5 (ApCht2, 5), endo-beta-N-acetylglucosaminidase (ApENGase) and chitin deacetylase (ApCDA) genes at 24 h and 48 h; The RNAi of ApTRE significantly down-regulated the expression of ApUAP, ApCht1, 2, 8 and ApCDA at 24 h and 48 h, and up-regulated the expression of glucose-6-phosphate isomerase (ApGPI) and Knickkopf protein (ApKNK) genes at 48 h. The RNAi of ApTRE and ApTPS not only altered the expression of chitin metabolism-related genes but also decreased the content of chitin. These results demonstrated that ApTPS and ApTRE can regulate the chitin metabolism, deepen our understanding of the biological functions, and provide a foundation for better understanding the molecular mechanism of insect metamorphosis.

Gene Characterization and Enzymatic Activities Related to Trehalose Metabolism of In Vitro Reared Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) under Sustained Cold Stress.

Simple SummaryTrehalose is a non-reducing disaccharide that presents in a wide variety of organisms, where it serves as an energy source or stress protectant. Trehalose is the most characteristic sugar of insect hemolymph and plays a crucial role in the regulation of insect growth and development. Trichogramma species are economically important egg parasitoids, which are being mass-produced for biological control programs worldwide. Many Trichogramma species could be mass reared on artificial mediums (not insect eggs), in which components contain insect hemolymph and trehalose. These in vitro-reared parasitoid wasps were strongly affected by cold storage, but prepupae could be successfully stored at 13 °C for up to 4 weeks. The aims of the present study were to determine the role of trehalose and the relationship between trehalose and egg parasitoid stress resistance. Our study revealed that (1) trehalose regulated the growth under sustained cold stress; (2) prepupal stage is a critical developmental period and 13 °C is the cold tolerance threshold temperature; (3) in vitro reared Trichogramma dendrolimi could be reared at temperatures of 16 °C, 20 °C, and 23 °C to reduce rearing costs. This finding identifies a low cost, prolonged development rearing method for T. dendrolimi, which will facilitate improved mass rearing methods for biocontrol.Trichogramma spp. is an important egg parasitoid wasp for biocontrol of agriculture and forestry insect pests. Trehalose serves as an energy source or stress protectant for insects. To study the potential role of trehalose in cold resistance on an egg parasitoid, cDNA for trehalose-6-phosphate synthase (TPS) and soluble trehalase (TRE) from Trichogramma dendrolimi were cloned and characterized. Gene expressions and enzyme activities of TdTPS and TdTRE were determined in larvae, prepupae, pupae, and adults at sustained low temperatures, 13 °C and 16 °C. TdTPS and TdTRE expressions had similar patterns with higher levels in prepupae at 13 °C and 16 °C. TdTPS enzyme activities increased with a decrease of temperature, and TdTRE activity in prepupae decreased sharply at these two low temperatures. In vitro reared T. dendrolimi could complete entire development above 13 °C, and the development period was prolonged without cold injury. Results indicated trehalose might regulate growth and the metabolic process of cold tolerance. Moreover, 13 °C is the cold tolerance threshold temperature and the prepupal stage is a critical developmental period for in vitro reared T. dendrolimi. These findings identify a low cost, prolonged development rearing method, and the cold tolerance for T. dendrolimi, which will facilitate improved mass rearing methods for biocontrol.

Ocean acidification, hypoxia and warming impair digestive parameters of marine mussels

Global change and anthropogenic activities have driven marine environment changes dramatically during the past century, and hypoxia, acidification and warming have received much attention recently. Yet, the interactive effects among these stressors on marine organisms are extremely complex and not accurately clarified. Here, we evaluated the combined effects of low dissolved oxygen (DO), low pH and warming on the digestive enzyme activities of the mussel Mytilus coruscus. In this experiment, mussels were exposed to eight treatments, including two degrees of pH (8.1, 7.7), DO (6, 2 mg/l) and temperature (30 °C and 20 °C) for 30 days. Amylase (AMS), lipase (LPS), trypsin (TRY), trehalase (TREH) and lysozyme (LZM) activities were measured in the digestive glands of mussels. All the tested stress conditions showed significant effects on the enzymatic activities. AMS, LPS, TRY, TREH showed throughout decreased trend in their activities due to low pH, low DO, increased temperature and different combinations of these three stressors with time but LZM showed increased and then decreased trend in their activities. Hypoxia and warming showed almost similar effects on the enzymatic activities. PCA showed a positive correlation among all measured biochemical parameters. Therefore, the fitness of mussel is likely impaired by such marine environmental changes and their population may be affected under the global change scenarios.

Effect of glycogen synthase and glycogen phosphorylase knockdown on the expression of glycogen- and insulin-related genes in the rice brown planthopper Nilaparvata lugens

Nilaparvata lugens is a serious threat to rice growth. Glycogen metabolism is one of the important physiological processes of insects, which is mainly regulated by glycogen synthase (GS) and glycogen phosphorylase (GP). In the present study, trehalose content was significantly reduced at 72 h after NlGP and NlGS knockdown, whereas glucose content was significantly increased at both 48 h and 72 h after GS knockdown. RNAi combined with RNA-Seq was used to identify NlGP- and NlGS-related pathways and genes in N. lugens. A total of 593 genes were up-regulated and 5969 genes were down-regulated after NlGP and NlGS knockdown, respectively. Moreover, the NlGS-knockdown group was mapped to 10,967 pathways, whereas the NlGP-knockdown group was mapped to 7948 pathways, and the greatest differences between the groups were associated with carbohydrate, lipid, amino acid and energy metabolism. Meanwhile, 1800, 1217, and 1211 transcripts in the NlGP-knockdown group and 2511, 1666, and 1727 transcripts in the NlGS-knockdown group were involved in bioprocess, cellular ingredients and molecular function, respectively. Almost all these genes were down-regulated by either NlGP or NlGS knockdown, with significant down-regulation of the 6-trehalose phosphate synthase (TPS), trehalase (TRE), GS, GP, phosphoacetylglucosamine mutase (PGM, n = 2), Insulin receptors (InRs) and insulin-like peptides (Ilps) genes. These results have demonstrated that RNAi-mediated NlGP and NlGS knockdown could lead to content of trehalose and glucose out of balance, but have no obvious effect on glycogen content, and have suggested that GS plays more complex role in other metabolism pathway of N. lugens.