Rapid surface plasmon resonance-based inhibition assay of deoxynivalenol

Deoxynivalenol belongs to a group of highly toxic fungal metabolites produced by Fusarium species that may contaminate food and animal feed, mostly grains. Three different monoclonal mouse anti-deoxynivalenol antibodies were compared for the development of a surface plasmon resonance (SPR)-based immunoassay for the selective and quantitative determination of deoxynivalenol in naturally contaminated matrices. A conjugate of deoxynivalenol with the protein casein was prepared and immobilized on the sensor chip surface. An excess of antibody was added to each test solution before the measurement. The assay was based on the competition for antibody binding between the immobilized deoxynivalenol conjugate on the sensor and the free deoxynivalenol molecules in the test solution. The deoxynivalenol-casein sensor could be reused more than 500 times without significant loss of activity using 6 M guanidine chloride solution for regeneration. The cross-reactivity of the three antibodies in the SPR assay was tested with other trichothecene mycotoxins (3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, nivalenol, HT2-toxin, and T2-toxin). The only sample preparation was extraction with max 80 vol % acetonitrile and 10-fold dilution with the running buffer. The assay had an optimal range between 2.5 and 30 ng/mL deoxynivalenol in the test solution. Most results of the SPR-based assay were in agreement with liquid chromatography/tandem mass spectrometry measurements of naturally contaminated wheat samples.     

Rheological properties of acid gels prepared from heated pH-adjusted skim milk

Reconstituted skim milk was adjusted to pH values between 6.5 and 7.1 and heated (90 degrees C) for up to 30 min. The skim milk samples were then readjusted to pH 6.7. Acid gels prepared from heated milk had markedly higher G ' values, a reduced gelation time, and an increased gelation pH than those prepared from unheated milk. An increased pH at heating decreased the gelation time, increased the gelation pH, and increased the final G ' of acid set gels prepared from the heated milk samples. There were only small differences in the level of whey protein denaturation in the samples at different pH values, and these differences could not account for the differences in the G ' of the acid gels. The levels of denatured whey protein associated with the casein micelles decreased and the levels of soluble denatured whey proteins increased as the pH at heating was increased. The results indicated that the soluble denatured whey proteins had a greater effect on the final G ' of the acid gels than the denatured whey proteins associated with the casein micelles.     

Graphoepitaxy of self-assembled block copolymers on two-dimensional periodic patterned templates

Self-assembling materials are the building blocks of bottom-up nanofabrication processes, but they need to be templated to impose long-range order and eliminate defects. In this work, the self-assembly of a thin film of a spherical-morphology block copolymer is templated using an array of nanoscale topographical elements that act as surrogates for the minority domains of the block copolymer. The orientation and periodicity of the resulting array of spherical microdomains are governed by the commensurability between the block copolymer period and the template period and is accurately described by a free-energy model. This method, which forms high-spatial-frequency arrays using a lower-spatial-frequency template, will be useful in nanolithography applications such as the formation of high-density microelectronic structures.     

Lhx2 selector activity specifies cortical identity and suppresses hippocampal organizer fate

The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer.     

Transmembrane segments of syntaxin line the fusion pore of Ca2+-triggered exocytosis

The fusion pore of regulated exocytosis is a channel that connects and spans the vesicle and plasma membranes. The molecular composition of this important intermediate structure of exocytosis is unknown. Here, we found that mutations of some residues within the transmembrane segment of syntaxin (Syx), a plasma membrane protein essential for exocytosis, altered neurotransmitter flux through fusion pores and altered pore conductance. The residues that influenced fusion-pore flux lay along one face of an alpha-helical model. Thus, the fusion pore is formed at least in part by a circular arrangement of 5 to 8 Syx transmembrane segments in the plasma membrane.     

Apple polyphenols extend the mean lifespan of Drosophila melanogaster

Apple polyphenols (AP) are an excellent source of dietary antioxidants. The present study investigated the effect of AP on the lifespan of fruit flies and their interaction with gene expressions of superoxide dismutase (SOD), catalase (CAT), methuselah (MTH), Rpn11, and cytochrome c oxidase (CcO) subunits III and VIb. Results showed the mean lifespan was significantly extended by 10% in fruit flies fed the AP diet. This was accompanied by up-regulation of genes SOD1, SOD2, and CAT and down-regulation of MTH in the aged fruit flies. Paraquat and H(2)O(2) challenge tests demonstrated that AP prolonged the survival time only for Oregon R wild type flies but not for SOD(n108) or Cat(n1) mutants, in which either SOD or CAT was knocked out. Chronic paraquat exposure could shorten the maximum lifespan from 68 to 31 days and reduce the climbing ability by 60%, whereas AP could partially reverse the paraquat-induced mortality and decline in climbing ability. AP could up-regulate Rpn11 at day 30, whereas it appeared to have no significant effect on gene expression of ubiquitinated protein, CcO subunits III and VIb. These AP-induced changes were unlikely associated with caloric restriction as the gustatory assay found no difference in average body weight and stomach redness index between the control and AP fruit flies. It was therefore concluded that the antiaging activity of AP was, at least in part, mediated by its interaction with genes SOD, CAT, MTH, and Rpn11.     

Effects of training on potassium homeostasis during exercise and skeletal muscle Na+,K(+)-ATPase concentration in young adult and middle-aged Dutch Warmblood horses

OBJECTIVE: To investigate the effects of moderate short-term training on K+ regulation in plasma and erythrocytes during exercise and on skeletal muscle Na+,K(+)-ATPase concentration in young adult and middle-aged horses. ANIMALS: Four 4- to 6-year-old and four 10- to 16-year-old Dutch Warmblood horses. PROCEDURE: The horses underwent a 6-minute exercise trial before and after 12 days of training. Skeletal muscle Na+,K(+)-ATPase concentration was analyzed in gluteus medius and semitendinosus muscle specimens before and after the 12-day training period. Blood samples were collected before and immediately after the trials and at 3, 5, 7, and 10 minutes after cessation of exercise for assessment of several hematologic variables and analysis of plasma and whole-blood K+ concentrations. RESULTS: After training, Na+,K(+)-ATPase concentration in the gluteus medius, but not semitendinosus, muscle of middle-aged horses increased (32%), compared with pretraining values; this did not affect the degree of hyperkalemia that developed during exercise. The development of hyperkalemia during exercise in young adult horses was blunted (albeit not significantly) without any change in the concentration of Na+,K(+)-ATPase in either of the muscles. After training, the erythrocyte K+ concentration increased (7% to 10%) significantly in both groups of horses but did not change during the exercise trials. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, the activation of skeletal muscle Na+,K(+)-ATPase during exercise is likely to decrease with age. Training appears to result in an increase in Na+,K(+)-ATPase activity in skeletal muscle with subsequent upregulation of Na+,K(+)-ATPase concentration if the existing Na+,K(+)-ATPase capacity cannot meet requirements.     

Structural requirements for the antimicrobial activity of carvacrol

Carvacrol is a component of several essential oils and has been shown to exert antimicrobial activity. The structural requirements for the activity of carvacrol were determined by comparison to structurally related (nonessential oil) compounds. Removal of the aliphatic ring substituents of carvacrol slightly decreased the antimicrobial activity. The effect of the hydroxyl group of carvacrol on activity could not be determined by simply comparing it to p-cymene, because this compound is immiscible with water; therefore, 2-amino-p-cymene, the amino analogue of carvacrol, which has a similar hydrophobicity and structural characteristics, was used. 2-Amino-p-cymene had similar membrane disruption and bacterial killing characteristics as carvacrol showing that, contrary to previous reports, the hydroxyl group of carvacrol itself is not essential for the antimicrobial activity. However, the observed 3-fold lower activity for 2-amino-p-cymene as compared to carvacrol indicates special features in the antimicrobial mode of action of carvacrol due to the hydroxyl group.