A proteomic approach to study the mechanism of tolerance to Bt toxins in Ostrinia furnacalis larvae selected for resistance to Cry1Ab

A Cry1Ab-resistant population of Asian corn borer (ACB-AbR) exhibiting approximately 100 times greater resistance to activated Cry1Ab than a susceptible population (Ostrinia furnacalis; ACB-BtS), was previously shown to exhibit high levels of cross-resistance to Cry1Ah (131-fold), but no cross-resistance to Cry1Ie. It was suggested that the proposed mechanism of resistance was due to the alteration of specific receptors for Cry toxins in the midgut brush border membrane. In the present study a proteomic-based approach was used to identify proteins from brush border membrane vesicles (isolated from both resistant and susceptible Ostrinia furnacalis larvae) interacting with biotinylated Cry1Ab, Cry1Ah, and Cry1Ie. 2D-Electrophoresis in combination with ligand blots were employed and putative protein identities obtained using MALDI-ToF/ToF mass spectrometry. The V-type proton ATPase catalytic subunit A and heat shock 70 kDa proteins were identified as interacting with the Cry toxins tested in the ACB-AbR and ACB-BtS larvae. The biotinylated Cry toxins showed markedly stronger interactions with proteins in the resistant compared to the susceptible larvae, suggesting an up-regulation of the V-type proton ATPase catalytic subunit A and heat shock 70 kDa proteins in the resistant (ACB-AbR) larvae. Interestingly, Cry1Ie interactions with the V-type proton ATPase catalytic subunit A in the ACB-BtS larvae appeared to be absent.     

Molecular cloning,expression profile,odorant affinity,and stability of two odorant‐binding proteins in Macrocentrus cingulum Brischke (Hymenoptera: Braconidae)

The polyembryonic endoparasitoid wasp Macrocentrus cingulum Brischke (Hymenoptera: Braconidae) is deployed successfully as a biocontrol agent for corn pest insects from the Lepidopteran genus Ostrinia in Europe and throughout Asia, including Japan, Korea, and China. The odorants are recognized, bound, and solubilized by odorant‐binding protein (OBP) in the initial biochemical recognition steps in olfaction that transport them across the sensillum lymph to initiate behavioral response. In the present study, we examine the odorant‐binding effects on thermal stability of McinOBP2, McinOBP3, and their mutant form that lacks the third disulfide bonds. Real‐time PCR experiments indicate that these two are expressed mainly in adult antennae, with expression levels differing by sex. Odorant‐binding affinities of aldehydes, terpenoids, and aliphatic alcohols were measured with circular dichroism spectroscopy based on changes in the thermal stability of the proteins upon their affinities to odorants. The obtained results reveal higher affinity of trans‐caryophelle, farnesene, and cis‐3‐Hexen‐1‐ol exhibits to both wild and mutant McinOBP2 and McinOBP3. Although conformational flexibility of the mutants and shape of binding cavity make differences in odorant affinity between the wild‐type and mutant, it suggested that lacking the third disulfide bond in mutant proteins may have chance to incorrect folded structures that reduced the affinity to these odorants. In addition, CD spectra clearly indicate proteins enriched with α‐helical content.     

大气CO2浓度升高对亚洲玉米螟生长发育及繁殖的影响

大气CO2浓度升高影响寄主植物的营养而间接影响节肢动物外,还直接影响许多昆虫的生长发育和繁殖。为探讨大气CO2浓度升高对亚洲玉米螟Ostrinia furnacalis(Guenée)生长发育和繁殖的影响,在CDCC-1型密闭式动态CO2气室内研究了当前大气CO2浓度375μl/L及大气CO2浓度分别升高0.5倍和1倍,即达到550μL/L和750μL/L条件下人工饲料饲养亚洲玉米螟实验种群生命表及其营养效应指标。结果表明,大气CO2浓度分别升高到550μL/L和750μL/L时,亚洲玉米螟幼虫成活率分别降低3.0%和8.9%;幼虫、蛹和成虫体重则没有显著差异;在750μL/L CO2浓度下幼虫和蛹历期分别显著延长13.1%和25.8%。虽然单雌产卵量和净增值率(R0)在大气高CO2浓度下有增加趋势,但未达到显著性差异。与当前大气CO2浓度相比,高CO2浓度下玉米螟的取食量分别增加9.1%和34.0%,排粪量分别增加42.3%和42.0%。     

转基因抗虫作物对非靶标昆虫的影响

转基因抗虫作物自 1996年被批准商业化种植以来 ,它的抗虫性和经济效益已得到了普遍肯定 ,同时 ,转基因抗虫作物对非靶标生物的影响 ,如转基因抗虫作物的长期种植 ,是否会导致次要害虫上升为主要害虫 ,是否会影响有益昆虫 ,包括重要经济昆虫、捕食性和寄生性天敌以及重要蝶类的种类及种群数量 ,已成为转基因抗虫作物生态风险评估的重要内容。一些研究结果表明 ,转基因抗虫作物在对靶标害虫有效控制的同时 ,一些对杀虫蛋白不敏感的非靶标害虫有加重危害的趋势 ,由于种植转基因抗虫作物 ,减少了化学农药的使用 ,客观上也使非靶标害虫种群数量上升 ,这对转基因抗虫作物害虫综合治理提出了新的要求。靶标害虫数量的减少直接影响了害虫天敌种群数量 ,靶标害虫取食转基因抗虫作物后发育迟缓 ,也间接影响了天敌昆虫的生长发育 ,转基因抗虫作物的花粉或花蜜是一些重要经济昆虫如蜜蜂、熊蜂和一些寄生蜂 ,甚至捕食性天敌的食物来源 ,或花粉飘落到一些鳞翅目昆虫如家蚕或重要蝶类昆虫的寄主植物上 ,直接或间接对这些昆虫造成一定影响。目前大多数研究表明转基因抗虫作物对非靶标昆虫 ,特别是对有益昆虫没有明显的不利影响 ,也有研究报道认为对某些有益昆虫有一定的不良影响。这为深入开展转基因抗虫作物的生态安全     

Integrated pest management is the lucrative bridge connecting the ever emerging knowledge islands of genetics and ecology

Integrated pest management （IPM） has long been considered a profit- and product （or technology）-driven multidisciplinary research field that maximizes crop yield and minimizes pest-inflicted economic losses. The introduction of transgenic crops has revolutionized crop protection and IPM by combining crop protection and genetics into one entity-the seed. Before the arrival of transgenic technology, studies of insect-plant interactions were frequently categorized under the field of ecology, and IPM programs were then the product of applied ecological research on suppressing pest populations in crop or livestock production.     

Aspirin inhibits adipogenesis of tendon stem cells and lipids accumulation in rat injury tendon through regulating PTEN/PI3K/AKT signalling

Tendon injury repairs are big challenges in sports medicine, and fatty infiltration after tendon injury is very common and hampers tendon injury healing process. Tendon stem cells (TSCs), as precursors of tendon cells, have shown promising effect on injury tendon repair for their tenogenesis and tendon extracellular matrix formation. Adipocytes and lipids accumulation is a landmark event in pathological process of tendon injury, and this may induce tendon rupture in clinical practice. Based on this, it is important to inhibit TSCs adipogenesis and lipids infiltration to restore structure and function of injury tendon. Aspirin, as the representative of non‐steroidal anti‐inflammatory drugs (NSAIDs), has been widely used in tendon injury for its anti‐inflammatory and analgesic actions, but effect of aspirin on TSCs adipogenesis and fatty infiltration is still unclear. Under adipogenesis conditions, TSCs were treated with concentration gradient of aspirin. Oil red O staining was performed to observe changes of lipids accumulation. Next, we used RNA sequencing to compare profile changes of gene expression between induction group and aspirin‐treated group. Then, we verified the effect of filtrated signalling on TSCs adipogenesis. At last, we established rat tendon injury model and compared changes of biomechanical properties after aspirin treatment. The results showed that aspirin decreased lipids accumulation in injury tendon and inhibited TSCs adipogenesis. RNA sequencing filtrated PTEN/PI3K/AKT signalling as our target. After adding the signalling activators of VO‐Ohpic and IGF‐1, inhibited adipogenesis of TSCs was reversed. Still, aspirin promoted maximum loading, ultimate stress and breaking elongation of injury tendon. In conclusion, by down‐regulating PTEN/PI3K/AKT signalling, aspirin inhibited adipogenesis of TSCs and fatty infiltration in injury tendon, promoted biomechanical properties and decreased rupture risk of injury tendon. All these provided new therapeutic potential and medicine evidence of aspirin in treating tendon injury and tendinopathy.     

Identification of cry1I-Type Genes from Bacillus thuringiensis Strains and Characterization of a Novel cry1I-Type Gene

A PCR-restriction fragment length polymorphism method for identification of cry1I-type genes from Bacillus thuringiensis was established by designing a pair of universal primers based on the conserved regions of the genes to amplify 1,548-bp cry1I-type gene fragments. Amplification products were digested with the Bsp119I and BanI enzymes, and four kinds of known cry1I-type genes were successfully identified. The results showed that cry1I-type genes appeared in 95 of 115 B. thuringiensis isolates and 7 of 13 standard strains. A novel cry1I-type gene was found in one standard strain and six isolates. The novel cry1I gene was cloned from B. thuringiensis isolate Btc007 and subcloned into vector pET-21b. Then it was overexpressed in Escherichia coli BL21(DE3). The expressed product was shown to be toxic to the diamondback moth (Plutella xylostella), Asian corn borer (Ostrinia furnacalis), and soybean pod borer (Leguminivora glycinivorella). However, it was not toxic to the cotton bollworm (Helicoverpa armigera), beet armyworm (Spodoptera exigua), or elm leaf beetle (Pyrrhalta aenescens) in bioassays. Subsequently, the Cry protein encoded by this novel cry gene was designated Cry1Ie1 by the B. thuringiensis δ-endotoxin nomenclature committee.     

Evaluation of spatial and temporal patterns of insect damage and aflatoxin level in the pre‐harvest corn fields to improve management tactics

Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre‐harvest corn fields, we further examined both spatial and temporal patterns of cob‐ and kernel‐feeding insect damage, and aflatoxin level with two samplings at pre‐harvest in 2008 and 2009. The feeding damage by each of the ear/kernel‐feeding insects (i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs) and maize weevil population were assessed at each grid point with five ears. Sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevils tended toward an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil number were more closely associated with aflatoxin level than was corn earworm damage. In addition, the indices of spatial–temporal association (χ) demonstrated that the number of maize weevils was associated between the first (4 weeks pre‐harvest) and second (1 week pre‐harvest) samplings in both years on all fields. In contrast, corn earworm damage between the first and second samplings from the field on the Belflower Farm, and aflatoxin level and corn earworm damage from the field on the Lang Farm were dissociated in 2009.     

pH-Controlled Bacillus thuringiensis Cry1Ac Protoxin Loading and Release from Polyelectrolyte Microcapsules

Crystal proteins synthesized by Bacillus thuringiensis (Bt) have been used as biopesticides because of their toxicity to the insect larval hosts. To protect the proteins from environmental stress to extend their activity, we have developed a new microcapsule formulation. Poly (acrylic acid) (PAH) and poly (styrene sulfonate) (PSS) were fabricated through layer-by-layer self-assembly based on a CaCO₃ core. Cry1Ac protoxins were loaded into microcapsules through layer-by-layer self-assembly at low pH, and the encapsulated product was stored in water at 4°C. Scanning electron microscopy (SEM) was used to observe the morphology of the capsules. To confirm the successful encapsulation, the loading results were observed with a confocal laser scattering microscope (CLSM), using fluorescein-labeled Cry1Ac protoxin (FITC-Cry1Ac). The protoxins were released from the capsule under the alkaline condition corresponding to the midgut of certain insects, a condition which seldom exists elsewhere in the environment. The following bioassay experiment demonstrated that the microcapsules with Cry1Ac protoxins displayed approximately equivalent insecticidal activity to the Asian corn borer compared with free Cry1Ac protoxins, and empty capsules proved to have no effect on insects. Further result also indicated that the formulation could keep stable under the condition of heat and desiccation. These results suggest that this formulation provides a promising methodology that protects protoxins from the environment and releases them specifically in the target insects’ midgut, which has shown potential as biopesticide in the field.