Oviposition and feeding avoidance in Helicoverpa armigera (Hübner) against transgenic Bt cotton

Helicoverpa armigera (Hübner), the major target pest of transgenic Bacillus thuringiensis (Bt) cotton, remains susceptible to Bt cotton in China at present. Behavioural avoidance by ovipositing females might lead to reduced exposure to Bt cotton and minimize selection for physiological resistance. We examined the behavioural responses of H. armigera to Bt and non‐Bt cottons to determine whether behavioural avoidance to Bt cotton may be present. In oviposition choice tests, the number of eggs on non‐Bt cotton plants was significantly higher than on Bt cotton plants. Similarly, in no‐choice tests, Bt cotton plants attracted significantly fewer eggs compared with non‐Bt cotton plants. H. armigera neonates showed higher dispersal and lower establishment on Bt cotton than on non‐Bt cotton. First instars were found to feed consistently on non‐Bt cotton leaves, creating large feeding holes, but only produced tiny feeding holes on Bt cotton leaves. The H. armigera population used in this study showed avoidance of oviposition and feeding on Bt cotton. Our results provide important insights into one possible mechanism underlying the durability of Bt cotton resistance and may be useful for improving strategies to sustain the effectiveness of Bt crops.     

Isolation and characterization of DNA microsatellite from cotton bollworm (Helicoverpa armigera,Hübner)

Five microsatellite loci of Helicoverpa armigera were isolated from a partial genomic library screened by oligonucleotide probes. Primers were designed to detect allelic variability and heterozygosity in 60 individuals collected from different host species. All loci were found to be polymorphic, have 8–11 alleles with expected heterozygosity ranging from 0.81 to 0.88. Our results indicate that the five microsatellite loci could provide valuable markers for population genetic and ecological studies of the cotton bollworm.     

Characterization of an Importin α/β‐recognized nuclear localization signal in β‐dystroglycan

β‐dystroglycan (β‐DG) is a widely expressed transmembrane protein that plays important roles in connecting the extracellular matrix to the cytoskeleton, and thereby contributing to plasma membrane integrity and signal transduction. We previously observed nuclear localization of β‐DG in cultured cell lines, implying the existence of a nuclear targeting mechanism that directs it to the nucleus instead of the plasma membrane. In this study, we delineate the nuclear import pathway of β‐DG, characterizing a functional nuclear localization signal (NLS) in the β‐DG cytoplasmic domain, within amino acids 776–782. The NLS either alone or in the context of the whole β‐DG protein was able to target the heterologous GFP protein to the nucleus, with site‐directed mutagenesis indicating that amino acids R⁷⁷⁹ and K⁷⁸⁰ are critical for NLS functionality. The nuclear transport molecules Importin (Imp)α and Impβ bound with high affinity to the NLS of β‐DG and were found to be essential for NLS‐dependent nuclear import in an in vitro reconstituted nuclear transport assay; cotransfection experiments confirmed the dependence on Ran for nuclear accumulation. Intriguingly, experiments suggested that tyrosine phosphorylation of β‐DG may result in cytoplasmic retention, with Y⁸⁹² playing a key role. β‐DG thus follows a conventional Impα/β‐dependent nuclear import pathway, with important implications for its potential function in the nucleus. J. Cell. Biochem. 110: 706–717, 2010. © 2010 Wiley‐Liss, Inc.     

棉铃虫成虫种群空间结构的研究

利用性诱捕器调查了棉铃虫越冬代至 3代棉铃虫成虫种群的种群密度 ,而后用 4种地统计模型拟合其种群的空间结构 ,并分析它们的空间关系 ,其结果如下 :( 1 )越冬代种群在全方位、90°及 1 3 5°方向上空间模型均为线型 ;在 0°及 4 5°方向上分别为球型和指数型 ,模型的参数表明越冬代成虫的空间相关距离为 6.0 1～ 8.0 1空间单位 (单位为 1 0 0 m,下同 ) ,异质系数为 54.60～ 83 .50 ,空间依赖度为 1 50 .0 0～ 1 80 .60。 ( 2 )一代种群在全方位、0°、4 5°、90°及 1 3 5°方向上的空间模型分别为线型、球型、线型、球型和球型 ;模型的种群参数表明一代成虫的空间异质系数是 53 6.0 0～ 588.1 0 ,相关距离为1 6.0 2～ 1 9.0 7空间单位 ,空间取样方差约是 2 60 0。 ( 3 )二代成虫在全方位、0°和 4 5°方向的空间模型均为指数型 ,在 90°及1 3 5°方向的模型均为球型 ;模型的参数表明二代成虫的空间异质系数为 5.56～ 2 5.93 ,空间取样方差是 53 .4 9～ 64 .96,相关距离为 4 .54～ 5.3 3空间单位。 ( 4)三代种群在全方位、0°、4 5°、90°及 1 3 5°方向的模型分别为指数型、球型、指数型、线型和指数型 ,模型的参数表明三代成虫的空间异质系数为 2 91 .93～ 4 93 .67,空间取样方差为 1 1 99.53～ 2     

The role of calcium in apoptosis induced by 7β‐hydroxycholesterol and cholesterol‐5β,6β‐epoxide

Oxysterols, such as 7β‐hydroxy‐cholesterol (7β‐OH) and cholesterol‐5β,6β‐epoxide (β‐epoxide), may have a central role in promoting atherogenesis. This is thought to be predominantly due to their ability to induce apoptosis in cells of the vascular wall and in monocytes/macrophages. Although there has been extensive research regarding the mechanisms through which oxysterols induce apoptosis, much remains to be clarified. Given that experimental evidence has long associated alterations of calcium (Ca²⁺) homeostasis to apoptotic cell death, the aim of the present study was to determine the influence of intracellular Ca²⁺ changes on apoptosis induced by 7β‐OH and β‐epoxide. Ca²⁺ responses in differentiated U937 cells were assessed by epifluorescence video microscopy, using the ratiometric dye fura‐2. Over 15‐min exposure of differentiated U937 cells to 30 μM of 7β‐OH induced a slow but significant rise in fura‐2 ratio. The Ca²⁺ channel blocker nifedipine and the chelating agent EGTA blocked the increase in cytoplasmic Ca²⁺. Moreover, dihydropyridine (DHP) binding sites identified with BODIPY‐FLX‐DHP were blocked following pretreatment with nifedipine, indicating that the influx of Ca²⁺ occurred through L‐type channels. However, following long‐term incubation with 7β‐OH, elevated levels of cytoplasmic Ca²⁺ were not maintained and nifedipine did not provide protection against apoptotic cell death. Our results indicate that the increase in Ca²⁺ may be an initial trigger of 7β‐OH–induced apoptosis, but following chronic exposure to the oxysterol, the influence of Ca²⁺ on apoptotic cell death appears to be less significant. In contrast, Ca²⁺ did not appear to be involved in β‐epoxide–induced apoptosis. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:324–332, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20295     

Comparative study of toxic effects of zearalenone and its two major metabolites α‐zearalenol and β‐zearalenol on cultured human Caco‐2 cells

Zearalenone (ZEN) is a fusarotoxin converted predominantly into α‐zearalenol (α‐Zol) and β‐zearalenol (β‐Zol) by hepatic hydroxysteroid dehydrogenases. The feeding of naturally contaminated grains with ZEN was associated with hyperestrogenic and adverse effects on humans and animals. There is a lack of information on the attribution of the toxic effects of these toxins. One wonders if these effects are due to the parent molecule (ZEN) or to its major metabolites (α‐Zol and β‐Zol). Using human Caco‐2 cells, we looked for the molecular mechanisms of toxicity of ZEN, α‐Zol, and β‐Zol. Toxicity effects were studied by MTT viability assay and oxidative stress induction by measuring malondialdehyde (MDA) generation. To check whether the oxidative stress induction was associated to DNA lesions, we looked for DNA fragmentation by means of the Comet and the diphenylamine assays. To specify cell death pathway, we investigated caspase‐3 activation, confirmed by poly(ADP‐ribose) polymerase cleavage and by Bcl‐2 depletion. Our results clearly demonstrated that ZEN as well as its two metabolites presented variable toxic effects. They induced cell death and an increase in MDA generation. These effects were associated to DNA fragmentation as well as caspase‐3 activation. The observed toxic effects seem to be relieved by the metabolism of ZEN into α‐Zol and β‐Zol. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:233–243, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20284     

5α‐Androst‐16‐en‐3α‐ol β‐D‐Glucuronide,Precursor of 5α‐Androst‐16‐en‐3α‐ol in Human Sweat

5α‐Androst‐16‐en‐3α‐ol (α‐androstenol) is an important contributor to human axilla sweat odor. It is assumed that α‐andostenol is excreted from the apocrine glands via a H₂O‐soluble conjugate, and this precursor was formally characterized in this study for the first time in human sweat. The possible H₂O‐soluble precursors, sulfate and glucuronide derivatives, were synthesized as analytical standards, i.e., α‐androstenol, β‐androstenol sulfates, 5α‐androsta‐5,16‐dien‐3β‐ol (β‐androstadienol) sulfate, α‐androstenol β‐glucuronide, α‐androstenol α‐glucuronide, β‐androstadienol β‐glucuronide, and α‐androstenol β‐glucuronide furanose. The occurrence of α‐androstenol β‐glucuronide was established by ultra performance liquid chromatography (UPLC)/MS (heated electrospray ionization (HESI)) in negative‐ion mode in pooled human sweat, containing eccrine and apocrine secretions and collected from 25 female and 24 male underarms. Its concentration was of 79 ng/ml in female secretions and 241 ng/ml in male secretions. The release of α‐androstenol was observed after incubation of the sterile human sweat or α‐androstenol β‐glucuronide with a commercial glucuronidase enzyme, the urine‐isolated bacteria Streptococcus agalactiae, and the skin bacteria Staphylococcus warneri DSM 20316, Staphylococcus haemolyticus DSM 20263, and Propionibacterium acnes ATCC 6919, reported to have β‐glucuronidase activities. We demonstrated that if α‐ and β‐androstenols and androstadienol sulfates were present in human sweat, their concentrations would be too low to be considered as potential precursors of malodors; therefore, the H₂O‐soluble precursor of α‐androstenol in apocrine secretion should be a β‐glucuronide.     

The stress response neuropeptide CRF increases amyloid‐β production by regulating γ‐secretase activity

The biological underpinnings linking stress to Alzheimer's disease (AD) risk are poorly understood. We investigated how corticotrophin releasing factor (CRF), a critical stress response mediator, influences amyloid‐β (Aβ) production. In cells, CRF treatment increases Aβ production and triggers CRF receptor 1 (CRFR1) and γ‐secretase internalization. Co‐immunoprecipitation studies establish that γ‐secretase associates with CRFR1; this is mediated by β‐arrestin binding motifs. Additionally, CRFR1 and γ‐secretase co‐localize in lipid raft fractions, with increased γ‐secretase accumulation upon CRF treatment. CRF treatment also increases γ‐secretase activity in vitro, revealing a second, receptor‐independent mechanism of action. CRF is the first endogenous neuropeptide that can be shown to directly modulate γ‐secretase activity. Unexpectedly, CRFR1 antagonists also increased Aβ. These data collectively link CRF to increased Aβ through γ‐secretase and provide mechanistic insight into how stress may increase AD risk. They also suggest that direct targeting of CRF might be necessary to effectively modulate this pathway for therapeutic benefit in AD, as CRFR1 antagonists increase Aβ and in some cases preferentially increase Aβ42 via complex effects on γ‐secretase.     

Lithium induces follicular atresia in rat ovary through a GSK‐3β/β‐catenin dependent mechanism

Lithium chloride (LiCl) is a drug used to treat bipolar disorder, but has side effects in the female reproductive system. Although lithium is known to decrease folliculogenesis and induce follicular atresia in rodent ovaries, its cellular and molecular effects in the ovary have not yet been addressed. To investigate these effects, 23‐day‐old immature female rats were injected with 10 IU pregnant mare serum gonadotropin (PMSG), followed by injections of 250 mg/kg LiCl every 12 hr for four doses. Ovaries were removed 40 and 48 hr after PMSG administration and prepared for histology, immunohistochemistry, Western blotting, and DNA laddering analysis. Our results showed that in the ovaries of LiCl‐treated rats, few antral but more atretic follicles were present compared to those of the control rats. The induction of atresia by LiCl was further confirmed by the presence of DNA fragmentation, accompanied by a reduced level of 17β‐estradiol in the serum. At the cellular level, lithium significantly decreased the number of proliferating cell nuclear antigen (PCNA)‐positive cells and conversely increased the number of TUNEL‐positive cells in the granulosa layer of the antral follicles. At the molecular level, lithium increased the level of phosphorylated glycogen synthase kinase‐3β, and unexpectedly decreased the expression of active (stabilized) β‐catenin. Altogether, our results indicate that lithium disrupts the balance between proliferation and apoptosis in granulosa cells, leading to follicular atresia possibly through the reduction in both the stabilized β‐catenin and 17β‐estradiol synthesis. Mol. Reprod. Dev. 80: 286–296, 2013. © 2013 Wiley Periodicals, Inc.     

BMP‐2 modulates β‐catenin signaling through stimulation of Lrp5 expression and inhibition of β‐TrCP expression in osteoblasts

Canonical BMP and Wnt signaling pathways play critical roles in regulation of osteoblast function and bone formation. Recent studies demonstrate that BMP‐2 acts synergistically with β‐catenin to promote osteoblast differentiation. To determine the molecular mechanisms of the signaling cross‐talk between canonical BMP and Wnt signaling pathways, we have used primary osteoblasts and osteoblast precursor cell lines 2T3 and MC3T3‐E1 cells to investigate the effect of BMP‐2 on β‐catenin signaling. We found that BMP‐2 stimulates Lrp5 expression and inhibits the expression of β‐TrCP, the F‐box E3 ligase responsible for β‐catenin degradation and subsequently increases β‐catenin protein levels in osteoblasts. In vitro deletion of the β‐catenin gene inhibits osteoblast proliferation and alters osteoblast differentiation and reduces the responsiveness of osteoblasts to the BMP‐2 treatment. These findings suggest that BMP‐2 may regulate osteoblast function in part through modulation of the β‐catenin signaling. J. Cell. Biochem. 108: 896–905, 2009. © 2009 Wiley‐Liss, Inc.     

Preparative Enantioseparation of β‐Substituted‐2‐Phenylpropionic Acids by Countercurrent Chromatography With Substituted β‐Cyclodextrin as Chiral Selectors

Preparative enantioseparation of four β‐substituted‐2‐phenylpropionic acids was performed by countercurrent chromatography with substituted β‐cyclodextrin as chiral selectors. The two‐phase solvent system was composed of n‐hexane‐ethyl acetate‐0.10 mol L‐1 of phosphate buffer solution at pH 2.67 containing 0.10 mol L^‐1 of hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) or sulfobutylether‐β‐cyclodextrin (SBE‐β‐CD). The influence factors, including the type of substituted β‐cyclodextrin, composition of organic phase, concentration of chiral selector, pH value of the aqueous phase, and equilibrium temperature were optimized by enantioselective liquid–liquid extraction. Under the optimum separation conditions, 100 mg of 2‐phenylbutyric acid, 100 mg of tropic acid, and 50 mg of 2,3‐diphenylpropionic acid were successfully enantioseparated by high‐speed countercurrent chromatography, and the recovery of the (±)‐enantiomers was in the range of 90–91% for (±)‐2‐phenylbutyric acid, 91–92% for (±)‐tropic acid, 85–87% for (±)‐2,3‐diphenylpropionic acid with purity of over 97%, 96%, and 98%, respectively. The formation of 1:1 stoichiometric inclusion complex of β‐substituted‐2‐phenylpropionic acids with HP‐β‐CD was determined by UV spectrophotometry and the inclusion constants were calculated by a modified Benesi‐Hildebrand equation. The results showed that different enantioselectivities among different racemates were mainly caused by different enantiorecognition between each enantiomer and HP‐β‐CD, while it might be partially caused by different inclusion capacity between racemic solutes and HP‐β‐CD. Chirality 27:795–801, 2015. © 2015 Wiley Periodicals, Inc.     

Basic conformers in β‐peptides

The conformation of oligomers of β‐amino acids of the general type Ac‐[β‐Xaa]_n‐NHMe (β‐Xaa = β‐Ala, β‐Aib, and β‐Abu; n = 1–4) was systematically examined at different levels of ab initio molecular orbital theory (HF/6‐31G*, HF/3‐21G). The solvent influence was considered employing two quantum‐mechanical self‐consistent reaction field models. The results show a wide variety of possibilities for the formation of characteristic elements of secondary structure in β‐peptides. Most of them can be derived from the monomer units of blocked β‐peptides with n = 1. The stability and geometries of the β‐peptide structures are considerably influenced by the side‐chain positions, by the configurations at the C^α‐ and C^β‐atoms of the β‐amino acid constituents, and especially by environmental effects. Structure peculiarities of β‐peptides, in particular those of various helix alternatives, are discussed in relation to typical elements of secondary structure in α‐peptides. © 1999 John Wiley & Sons, Inc. Biopoly 50: 167–184, 1999     

Phylogenetic relationships of the callitrichinae (Platyrrhini,Primates) based on β2‐microglobulin DNA sequences

The phylogenetic relationships of callitrichine primates have been determined by DNA sequence analyses of exons 1, 2, and 3 of the β₂‐microglobulin gene. Parsimony, distance, and maximum likelihood analyses of ca. 900 base pairs of 21 taxa, representing all callitrichine genera, indicated that Saguinus was the most basal offshoot. Within Saguinus, S. fuscicollis appeared as the first divergent lineage followed by an unresolved trichotomy formed by S. mystax/S. imperator, S. midas/S. bicolor, and S. oedipus. A second callitrichine lineage was formed by Leontopithecus; each of the three species studied showed identical nucleotide sequences. Callimico appeared as the sister taxon of Callithrix/Cebuella. Genetic distances within this latter group were very small, although a stronger association between Cebuella and species of the Callithrix argentata group was observed. The inclusion of Cebuella in the genus Callithrix is suggested. These studies indicated that tamarins are more plesiomorphic than marmosets in agreement with the phyletic dwarfism hypothesis. Am. J. Primatol. 48:225–236, 1999. © 1999 Wiley‐Liss, Inc.     

Cytotoxic (9βH)‐Pimarane and (9βH)‐17‐Norpimarane Diterpenes from the Tuber of Icacina trichantha

Three (9βH)‐pimaranes, 1, 2 , and 3 , and two (9βH)‐17‐norpimaranes, 4 and 5 , belonging to a rare compound class in nature, were obtained from the tubers of Icacina trichantha for the first time. Compound 1 is a new natural product, and 2 – 5 have been previously reported. The structures were elucidated based on NMR and MS data, and optical rotation values. The absolute configurations of (9βH)‐pimaranes were unambiguously established based on X‐ray crystallographic analysis. Full NMR signal assignments for the known compounds 2, 4 , and 5 , which were not available in previous publications, are also reported. All five isolates displayed cytotoxic activities on MDA‐MB‐435 cells (IC₅₀ 0.66–6.44 μM ), while 2, 3 , and 4 also exhibited cytotoxicities on HT‐29 cells (IC₅₀ 3.00–4.94 μM ).     

Amyloid β‐induced astrogliosis is mediated by β1‐integrin via NADPH oxidase 2 in Alzheimer's disease

Astrogliosis is a hallmark of Alzheimer′s disease (AD) and may constitute a primary pathogenic component of that disorder. Elucidation of signaling cascades inducing astrogliosis should help characterizing the function of astrocytes and identifying novel molecular targets to modulate AD progression. Here, we describe a novel mechanism by which soluble amyloid‐β modulates β1‐integrin activity and triggers NADPH oxidase (NOX)‐dependent astrogliosis in vitro and in vivo. Amyloid‐β oligomers activate a PI3K/classical PKC/Rac1/NOX pathway which is initiated by β1‐integrin in cultured astrocytes. This mechanism promotes β1‐integrin maturation, upregulation of NOX2 and of the glial fibrillary acidic protein (GFAP) in astrocytes in vitro and in hippocampal astrocytes in vivo. Notably, immunochemical analysis of the hippocampi of a triple‐transgenic AD mouse model shows increased levels of GFAP, NOX2, and β1‐integrin in reactive astrocytes which correlates with the amyloid β‐oligomer load. Finally, analysis of these proteins in postmortem frontal cortex from different stages of AD (II to V/VI) and matched controls confirmed elevated expression of NOX2 and β1‐integrin in that cortical region and specifically in reactive astrocytes, which was most prominent at advanced AD stages. Importantly, protein levels of NOX2 and β1‐integrin were significantly associated with increased amyloid‐β load in human samples. These data strongly suggest that astrogliosis in AD is caused by direct interaction of amyloid β oligomers with β1‐integrin which in turn leads to enhancing β1‐integrin and NOX2 activity via NOX‐dependent mechanisms. These observations may be relevant to AD pathophysiology.