Deterrence of feeding and oviposition responses of adult Heliothis virescens by some compounds bitter-tasting to humans

Some compounds that are bitter-tasting to humans, both alkaloidal (quinine, quinidine, atropine, caffeine) and non-alkaloidal (denatonium benzoate, sucrose octaacetate, naringin), deterred feeding and oviposition by Heliothis virescens (F.) in laboratory and field cage experiments. Preliminary electrophysiological studies of gustatory sensilla on the ovipositor of H. virescens provided evidence of 3 neurons, one of which is responsive to sucrose. Preliminary indications are that responses of this neuron may be inhibited by quinine and denatonium benzoate.     

Responses of cultured rat trigeminal ganglion neurons to bitter tastants

The initial steps in taste and olfaction result from the activation by chemical stimuli of taste receptor cells (TRCs) and olfactory receptor neurons (ORNs). In parallel with these two pathways is the chemosensitive trigeminal pathway whose neurons terminate in the oral and nasal cavities and which are activated by many of the same chemical stimuli that activate TRCs and ORNs. In a recent single unit study we investigated the responses of rat chorda tympani and glossopharnygeal neurons to a variety of bitter-tasting alkaloids, including nicotine, yohimbine, quinine, strychnine and caffeine, as well as capsaicin, the pungent ingredient in hot pepper. Here we apply many of these same compounds to cultured rat trigeminal ganglion (TG) neurons and measure changes in intracellular calcium [Ca2+]i to determine whether TG neurons will respond to these same compounds. Of the 89 neurons tested, 34% responded to 1 mM nicotine, 7% to 1 mM caffeine, 5% to 1 mM denatonium benzoate, 22% to 1 mM quinine hydrochloride, 18% to 1 mM strychnine and 55% to 1 microM capsaicin. These data suggest that neurons from the TG respond to the same bitter-tasting chemical stimuli as do TRCs and are likely to contribute information sent to the higher CNS regarding the perception of bitter/irritating chemical stimuli.      

Individual differences in sensitivity to bitter-tasting substances

Perception of several bitter-tasting compounds was tested in52 subjects. Stable individual differences in the perceivedintensity of the bitterness of suprathreshold concentrationsof quinine sulfate (QSO₄) and urea were found. Whereas 18 subjectsjudged selected concentrations of these compounds to be equallybitter, 17 found QSO₄ to be more bitter than urea, and 17 foundurea to be more bitter than QSO₄. These reliable individualdifferences were significantly related to threshold sensitivityto QSO₄; that is, individuals who perceived QSO₄ to be moreintense than urea at suprathreshold concentrations also hadlower QSO₄ thresholds than did those who perceived urea to bemore intense than QSO₄. There appeared to be no relationshipbetween the relative perceived intensities of these compoundsand rating of the bitterness of PROP (6-n-propylthiouracil).However, QSO₄-sensitive individuals tended to find the bitternessof suprathreshold caffeine and sucrose octaacetate to be greaterthan that of suprathreshold magnesium sulfate, whereas the reversewas true for urea-sensitive individuals. This pattern parallelsthe pattern of cross-adaptation among these compounds reportedby other investigators. These results are consistent with theexistence of multiple bitter transduction sequences and suggestthat individual differences in response to various bitter compoundsmay reflect differences in teh relative availability of specifictransduction sequences.     

ELECTROPHORETIC AND MORPHOMETRIC CHARACTERS IN POPULATION DIFERENTIATION OF THE PEARL OYSTER, PINCTADA RADIATA (LEACH), FROM AROUND BAHRAIN

Variation at the leucine aminopeptidase (Lap), glucose phosphateisomerase (Gpi) and tetrazolium oxidase (To) loci was investigatedin samples of three populations, Al-Mayana (MAY), Shigita (SH)and Mina Salman (MS), of Pinctada radiata from pearl oysterbeds around Bahrain. The To locus was monomor-phic. SignificantLap and Gpi heterozygote deficiencies were evident and it issuggested that these were generated by selection. The MS population,to the East of Bahrain, differed significantly in Gpi allelefrequencies from both Northern populations (MAY, SH) and Nei'sgenetic identity indicates a close relationship between theNorthern populations. Measurements of shell morphometrics were used both as ratiosof one dimension to another, and as regressions of one dimensionon another to examine relatedness between populations. Boththese mor-phometric approaches gave different results from eachother and also differed from the electrophoretic data. It isconcluded that estimates of relatedness in pearl oysters basedon electrophoretic data will be more reliable than those basedon shell shape. (Received 20 November 1990; accepted 12 April 1991)     

Effect of proline on wound vessel member formation

Pretreatment of Coleus blumei (BENTH.) stem explants for 24hr with L-proline (P) (1.0 mM) by the successive cup techniqueresulted in the redifferentiation of extremely high numbersof wound vessel members (WVM) from pith and cortical parenchymatissues following the addition of a xylogenic concentrationof 5 ppm indoleacetic acid (IAA). The addition of P with auxinor after auxin had been introduced into the segments was ineffectivein altering the numbers of WVM formed as compared to controls.P-treated segments showed both normal and aberrant WVM withthe addition of colchicine (0.01 %) and IAA; colchicine-treatedsegments invariably produced aberrant WVM when P and IAA weregiven. These results suggest that a P-rich substance may interactwith auxin in initiating wound vessel member differentiation. ¹Fulbright Professor of Botany, 1967-68. Permanent address:Department of Biological Sciences, University of Idaho, Moscow,Idaho, 83843, U. S. A.     

Electrophysiological characterization of the node in Chara corallina: functional differentiation for wounding response

Electrical characteristics of the node were analyzed in comparisonwith those of the flank of the internodal cell in Chara corallina.The dependence of the membrane potential of the node on pH andK⁺ concentration was almost the same as that of the flank. Inthe flank, the increase in the Ca²⁺ concentration stopped thedepolarization in the presence of 100 mM KCl. In the node, however,Ca²⁺ could not stop the depolarization induced by 100 mM KCl.It has been reported that the node has a function to tranducethe signal of osmotic shock into a transient depolarization.In combination with osmotic shock, 10 mM K⁺ could induce a long-lastingdepolarization of the node. These electrical characteristicsof the node were suggested to be responsible for the electricalresponse to wounding in Characeae.     

Effect of Dormancy Relieving Compounds on the Seed Germination of Non-dormantAllenrolfea occidentalisunder Salinity Stress

Allenrolfea occidentalis(Chenopodiaceae) is a highly salt tolerantplant species that is widely distributed in inland salt marshesand salt playas of the western United States. We investigatedthe influence of dormancy-relieving compounds (fusicoccin, ethephon,nitrate and thiourea) in alleviating salinity stress on theseed germination ofA. occidentalis. Seed germination decreasedwith an increase in salinity and no seed germinated at 800 mMNaCl.Fusicoccin (5 µM), ethephon (10 mM) and nitrogenous compounds(20 mMnitrate and 10 mMthiourea) were able to counteract theinhibition produced by salinity treatments. All dormancy relievingcompounds significantly (P<0.0001) promoted germination atall salinity concentations. Fusicoccin completely reversed theinhibitory effects of salinity on seed germination ofA. occidentalis.Ethephon application significantly promoted germination at allsalinities. Nitrate and thiourea were relatively less effectivein alleviating the effects of high salinity on germination.Copyright1998 Annals of Botany Company Allenrolfea occidentalis, ethephon, fusicoccin, halophyte, dormancy, nitrate, salinity, seed germination, thiourea.     

Specificity of Glossopharyngeal Nerve Responses to Astringent Compounds in Xenopus

Astringent compounds were applied to oral epithelium of theclawed toad, Xenopus laevis, and rapidly rising and highly sensitiveresponses could be recorded from the whole glossopharyngealnerve, but not at all from the trigeminal nerve. The responseto 10 mM tannic acid decreased progressively with repetitiveapplication. These responses to tannic acid, however, recoveredcompletely by treating with chemicals capable of forming stronghydrogen and hydrophobic bonds. These chemical bondings aregenerally recognized as a model for polyphenol (tannin)-proteininteractions based on physico-chemical measurements in vitro.The high affinities of these chemicals for tannic acid may beeffective in releasing both bonds in the interaction of tannicacid with the receptor molecules. Our results provide in vivoevidence for this model. Chem. Senses 21: 459–465, 1996.     

In defence of the Cell Quota model of micro-algal growth

When proper statistical procedures were employed, the empiricalCell Quota model of Droop (J. Mar. Biol. Assoc. UK, 48, 689–733,1968; J. Phycol., 9, 264–272, 1973) proved a better fitto 20 out of 21 data sets (of conserved nutrients) than didthe power law-based Chemical Reaction model of Baird (J. PlanktonRes., 21, 85–126, 1999).     

The signaling role of extracellular ATP and its dependence on Ca2+ flux in elicitation of Salvia miltiorrhiza hairy root cultures

The application of a polysaccharide elicitor from yeast extract,YE, to Salvia miltiorrhiza hairy root cultures induced transientrelease of ATP from the roots to the medium, leading to a dose-dependentincrease in the extracellular ATP (eATP) level. The eATP levelrose to a peak (about 6.5 nM with 100 mg l^–1 YE) at about10 h after YE treatment, but dropped to the control level 6h later. The elicitor-induced ATP release was dependent on membraneCa²⁺ influx, and abolished by the Ca²⁺ chelator EGTA or thechannel blocker La³⁺. The YE-induced H₂O₂ production was stronglyinhibited by reactive blue (RB), a specific inhibitor of membranepurinoceptors. On the other hand, the application of exogenousATP at 10–100 µM to the cultures also induced rapidand dose-dependent increases in H₂O₂ production and medium pH,both of which were effectively blocked by RB and EGTA. The non-hydrolyzableATP analog ATPS was as effective as ATP, but the hydrolyzedderivatives ADP or AMP were not so effective in inducing thepH and H₂O₂ increases. Our results suggest that ATP releaseis an early event and that eATP plays a signaling role in theelicitation of plant cell responses; Ca²⁺ is required for activationof the elicitor-induced ATP release and the eATP signal transduction.This is the first report on ATP release induced by a fungalelicitor and its involvement in the elicitor-induced responsesin plant cells.     

A multivariate test of association

Summary: Although genetic association studies often test multiple,related phenotypes, few formal multivariate tests of associationare available. We describe a test of association that can beefficiently applied to large population-based designs. Availability: A C++ implementation can be obtained from theauthors. Contact: manuel.ferreira{at}qimr.edu.au Supplementary information: Supplementary figures are availableat Bioinformatics online. Associate Editor: Alex Bateman     

Three-dimensional holograph vector of atomic interaction field (3D-HoVAIF): a novel rotation-translation invariant 3D structure descriptor and its applications to peptides.

Quantitative structure-activity relationship (QSAR) study, important in drug design, mainly involves two aspects, molecular structural characterization (MSC) and construction of a statistical model. MSC focuses on transforming molecular structural and property characteristics into a group of numerical codes, dedicated to minimizing information loss during this process. In this context, common atoms in organic compounds are classified according to their families in the periodic table, and hybridization states, and on the basis of these, three nonbonding interactions (i.e. electrostatic, van der Waals and hydrophobic) are calculated, ultimately resulting in a new rotation-translation invariant, 3D-MSC, as a three-dimensional holograph vector of atomic interaction field (3D-HoVAIF). By applying 3D-HoVAIF to QSAR studies on two classical peptides including 58 angiotensin-converting enzyme (ACE) inhibitors and 48 bitter-tasting dipeptides, we get two excellent genetic algorithm-partial least squares (GA-PLS) models, with statistics r(2), q(2), root mean square error (RMSEE), and root mean square error of cross-validation (RMSCV) of 0.857, 0.811, 0.376, and 0.432 for ACE inhibitors and 0.940, 0.892, 0.153 and 0.205 for bitter-tasting dipeptides, respectively. By equally dividing the two datasets into training and test sets by D-optimal, the 3D-HoVAIF approach undergoes rigorous statistical validation. Furthermore, the superior performance of 3D-HoVAIF is confirmed in comparison with two other peptide MSC approaches referring to z-scale and ISA-ECI. For 58 ACE inhibitors, the GA-PLS model yields two principal components, with the following statistics: r(2) = 0.893, q(2) = 0.824, RMSEE = 0.349, RMSCV = 0.425, q2(ext) = 0.739, r2(ext)= 0.784, r2(0.ext) = 0.781, rf2(0.ext) = 0.77, k = 0.962, k' = 1.019, and RMSEP = 0.460; for 48 bitter-tasting dipeptides, three principal components resulted, with the statistics as: r(2) = 0.950, q(2) = 0.893, RMSEE = 0.152, RMSCV = 0.222, q2(ext)= 0.875, r2(ext) = 0.919, r2(0.ext)= 0.919, rf2(0.ext)= 0.919, k = 1.018, k' = 0.974, and RMSEP = 0.198. In addition, the relationship of ACE-inhibiting activities with bitter-tasting thresholds has been investigated by applying the above-constructed models to predictions on 400 theoretically possible dipeptides. Through analysis, the ACE-inhibiting activities are found to be prominently related to bitter-tasting intensities. Thus, it is deemed to be difficult to find such dipeptides that simultaneously satisfy pharmacodynamic action (high ACE-inhibiting activities) and comfortable tastes, suggesting that active components of dipeptides that are served as functional food to lower blood pressure are not very ideal.     

Practical FDR-based sample size calculations in microarray experiments

Motivation: Owing to the experimental cost and difficulty inobtaining biological materials, it is essential to considerappropriate sample sizes in microarray studies. With the growinguse of the False Discovery Rate (FDR) in microarray analysis,an FDR-based sample size calculation is essential. Method: We describe an approach to explicitly connect the samplesize to the FDR and the number of differentially expressed genesto be detected. The method fits parametric models for degreeof differential expression using the Expectation–Maximizationalgorithm. Results: The applicability of the method is illustrated withsimulations and studies of a lung microarray dataset. We proposeto use a small training set or published data from relevantbiological settings to calculate the sample size of an experiment. Availability: Code to implement the method in the statisticalpackage R is available from the authors. Contact: jhu{at}mdanderson.org     

AIMIE: a web-based environment for detection and interpretation of significant sequence motifs in prokaryotic genomes

Motivation: Genomes contain biologically significant informationthat extends beyond that encoded in genes. Some of this informationrelates to various short dispersed repeats distributed throughoutthe genome. The goal of this work was to combine tools for detectionof statistically significant dispersed repeats in DNA sequenceswith tools to aid development of hypotheses regarding theirpossible physiological functions in an easy-to-use web-basedenvironment. Results: Ab Initio Motif Identification Environment (AIMIE)was designed to facilitate investigations of dispersed sequencemotifs in prokaryotic genomes. We used AIMIE to analyze theEscherichia coli and Haemophilus influenzae genomes in orderto demonstrate the utility of the new environment. AIMIE detectedrepeated extragenic palindrome (REP) elements, CRISPR repeats,uptake signal sequences, intergenic dyad sequences and severalother over-represented sequence motifs. Distributional patternsof these motifs were analyzed using the tools included in AIMIE. Availability: AIMIE and the related software can be accessedat our web site http://www.cmbl.uga.edu/software.html. Contact: mrazek{at}uga.edu Associate Editor: Alex Bateman     

CRONOS: the cross-reference navigation server

Summary: Cross-mapping of gene and protein identifiers betweendifferent databases is a tedious and time-consuming task. Toovercome this, we developed CRONOS, a cross-reference serverthat contains entries from five mammalian organisms presentedby major gene and protein information resources. Sequence similarityanalysis of the mapped entries shows that the cross-referencesare highly accurate. In total, up to 18 different identifiertypes can be used for identification of cross-references. Thequality of the mapping could be improved substantially by exclusionof ambiguous gene and protein names which were manually validated.Organism-specific lists of ambiguous terms, which are valuablefor a variety of bioinformatics applications like text miningare available for download. Availability: CRONOS is freely available to non-commercial usersat http://mips.gsf.de/genre/proj/cronos/index.html, web servicesare available at http://mips.gsf.de/CronosWSService/CronosWS?wsdl. Contact: brigitte.waegele{at}helmholtz-muenchen.de Supplementary information: Supplementary data are availableat Bioinformatics online. The online Supplementary Materialcontains all figures and tables referenced by this article. Associate Editor: Martin Bishop     

GOTreePlus: an interactive gene ontology browser

Summary: We developed an interactive gene ontology (GO) browsernamed GOTreePlus that superimposes annotation information overGO structures. It can facilitate the identification of importantGO terms through interactive visualization of them in the GOstructure. The interactive pie chart summarizing an annotationdistribution for a selected GO term provides users with a succinctcontext-sensitive overview of their experimental results. Wetested our GOTreePlus using a proteome profiling dataset obtainedon differentiation of retinal pigment epithelial cells where399 proteins were quantified. Availability: http://bioinformatics.cnmcresearch.org/GOTreePlus/ Contact: jseo{at}cnmcresearch.org Associate Editor: John Quackenbush