Central Mechanisms of Pheromone Information Processing

An advantage of using pheromones in olfactory studies is thatthey are chemical signals for which receptor neurons are evolvedand thus elicite biologically relevant odour-information tobe processed in the brain. In many vertebrate and insect species,the olfactory system is separated into a ‘main’and an ‘accessory’ division, the latter mediatingpheromone information. In moths, the pheromone information isfirst processed in the brain in a large and sexually dimorphicstructure, the macroglomerular complex (MGC) of the antennallobe (AL). Also in vertebrates the pheromone information isprocessed in specific or modified glomerular complexes. Oneprinciple question is whether individual olfactory glomeruliare functional units, processing specific information concerningboth the chemical quality and spatiotemporal features of thestimulus, like the pheromone plume. Indeed it has been shownthat the axons of different pheromone-selective receptor neuronsproject into different MGC-glomeruli. Intracellular recordingsfrom the AL projection (output) neurons also show that informationabout single components of the pheromone blend is preservedin some output pathways, whereas other output neurons respondin a unique fashion to the blend. The information about interspecificsignals, which interrupts pheromone attraction, is processedin a specific MGC-glomerulus and is to a large extent kept separatedfrom the pheromone information throughout the AL. Many of theoutput neurons accurately encode changes in the temporal characteristicsof the stimulus. Chem. Senses 21: 269–275, 1996.     

Are the Tastes of Polycose and Monosodium Glutamate Unique?

To study whether Polycose and monosodium L-glutamate (L-MSG)have unique tastes differing from the traditional four basictastes, chemosensory profiles were established for Polycose,L-MSG and a group of related compounds (sucrose, maltose, monosodiumD-glutamate (D-MSG), sodium chloride, calcium chloride). Flavourswere assessed using whole-mouth tests in human subjects withnose open or clamped to reduce olfactory input. Polycose (amixture of glucose-based oligosaccharides) had a flavor consistingof an olfactory component and a maltose-like taste. L-MSG andD-MSG profiles differed from each other, and from NaCl and CaCl₂.L-MSG had a lower threshold and a higher frequency of ‘other’tastes than the D form. The data do not support a ‘polysaccharide’taste, but suggest a chiral receptor site for ‘umami’taste. Chem. Senses 21: 341–347, 1996.     

Taste- and odor-reactivity in elderly demented patients

Previous studies demonstrated that hedonically different chemical(taste or smell) stimuli induceinnate, inherited, differentialand distinct fixed reflectory motion features in the oral andfacial area. In the present study 20 elderly demented patients,suffering from ‘probable’ or ‘possible’Alzheimer's disease, and 20 normally functioning elderly subjectswere tested. The facial expressive behavioral reactions triggeredby a set of common gustatory and olfactory stimuli were videotaped.Both psychophysical and stimulus-dependent behavioral responseswere obtained from the control group, while for the dementedpatients only behavioral reactions were recorded. Results revealedthat: (i) severely demented elderly subjects displayed differentialand distinct orofacial responses indicating ‘acceptance’and ‘aversion’. These were found to be analogousto but less intense than those displayed by control age mates;(ii) the duration of responses induced by aversive tastes islonger than that triggered by pleasant or indifferent ones,for both groups; (iii) all gustatory and olfactory stimuli triggera longer lasting behavioral response in demented than in normalsubjects; and (iv) psychophysical and behavioral responses ofthe control subjects gave similar results for taste- and odor-hedonicsas well as for their intensity. This finding clearly indicatesthe validity of the alternative use of psychophysical and behavioraltesting procedures.     

ERRATA

WARBURG, M. R., 1965. On the water economy of some Australianland snails. Proc. malac. Soc. Lond. 36, 297–305. Page 298: second line from bottom, should read ‘within± 1 µg for Themapupa’. Page 300: Fig. 2 legend, should read ‘Evaporative waterloss from Sinumelon remissum (a), Pleuroxia sp. (b) and Themapupaadelaidae (c)’. Page 300: section 4 heading, should read ‘Continuous curvesfor water loss’. Page 301: second line, for ‘Fig. 9’ read ‘Fig.3’. Page 301: Table 1, last line, for ‘0.120024’ read‘0.12024’. Present address: Israel Institute for Biological Research, Ness-Ziona,Israel.     

e-LiSe--an online tool for finding needles in the '(Medline) haystack'

Summary: Using literature databases one can find not only knownand true relations between processes but also less studied,non-obvious associations. The main problem with discoveringsuch type of relevant biological information is ‘selection’.The ability to distinguish between a true correlation (e.g.between different types of biological processes) and randomchance that this correlation is statistically significant iscrucial for any bio-medical research, literature mining beingno exception. This problem is especially visible when searchingfor information which has not been studied and described inmany publications. Therefore, a novel bio-linguistic statisticalmethod is required, capable of ‘selecting’ truecorrelations, even when they are low-frequency associations.In this article, we present such statistical approach basedon Z-score and implemented in a web-based application ‘e-LiSe’. Availability: The software is available at http://miron.ibb.waw.pl/elise/ Contact: piotr{at}ibb.waw.pl Supplementary information: Supplementary materials are availableat http://miron.ibb.waw.pl/elise/supplementary/ Associate Editor: Alfonso Valencia     

Discrimination of sex pheromone blends in the olfactory system of the moth

Intracellular analysis of olfactory neurons in the internallobes of several speicies of months has revealed a psysiologisallydivorse population of projection neurons connecting the pheromone-processingcenter (the male-specific macroglormerular complex) with severalarea of the protocerebrum. Some of these output elements carryinformation about only a single pheromone in the female's complexblend, which is consistent with the ‘component hypothesis’of behavioral excitation. Other output neurons, which receivemore complex synaptic input, can distinguish the complete blendfrom the individual pheromones, thereby lending support to the‘blend hypothesis’ of behavioral excitation. Theresults suggest that even within the pheromone-processing subsystermin male insects, which is largely distinct from the rest ofthe olfactory system, there exist different but parallel linesof pheromonal information coding that ultimately govern thesteteotyped mate-seeking behaviors.     

Evaluating the 'Labeled Magnitude Scale' for Measuring Sensations of Taste and Smell

The Labeled Magnitude Scale (LMS) is a semantic scale of perceptualintensity characterized by a quasi-logarithmic spacing of itsverbal labels. The LMS had previously been shown to yield psychophysicalfunctions equivalent to magnitude estimation (ME) when gustatory,thermal and nociceptive stimuli were presented and rated together,and the upper bound of the LMS was defined as the ‘strongestimaginable oral sensation’. The present study comparedthe LMS to ME within the more limited contexts of taste andsmell. In Experiment 1, subjects used both methods to rate eithertaste intensity produced by sucrose and NaCl or odor intensityproduced by acetic acid and phenyl ethyl alcohol, with the upperbound of the LMS defined as either the ‘strongest imaginabletaste’ or the ‘strongest imaginable odor’.The LMS produced psychophysical functions equivalent to thoseproduced by ME. In Experiment 2 a new group of subjects usedboth methods to rate the intensity of three different tastequalities, with the upper bound of the LMS defined as the ‘strongestimaginable [sweetness, saltiness, or bitterness]’. Inall three cases the LMS produced steeper functions than didME. Experiment 3 tested the hypothesis that the LMS yields datacomparable to ME only when the perceptual domain under studyincludes painful sensations. This hypothesis was supported whenthe LMS again produced steeper functions than ME after subjectshad been explicitly instructed to omit painful sensations (e.g.the ‘burn’ of hot peppers) from the concept of ‘strongestimaginable taste’. We conclude that the LMS can be usedto scale sensations of taste and smell when they are broadlydefined, but that it should be modified for use in scaling specifictaste (and probably odor) qualities. The implications of theseresults for theoretical issues related to ME, category-ratioscales and the size of the perceptual range in different sensorymodalities are discussed. Chem. Senses 21: 323–334, 1996.     

A comprehensive assessment of sequence-based and template-based methods for protein contact prediction

Motivation: Pair-wise residue-residue contacts in proteins canbe predicted from both threading templates and sequence-basedmachine learning. However, most structure modeling approachesonly use the template-based contact predictions in guiding thesimulations; this is partly because the sequence-based contactpredictions are usually considered to be less accurate thanthat by threading. With the rapid progress in sequence databasesand machine-learning techniques, it is necessary to have a detailedand comprehensive assessment of the contact-prediction methodsin different template conditions. Results: We develop two methods for protein-contact predictions:SVM-SEQ is a sequence-based machine learning approach whichtrains a variety of sequence-derived features on contact maps;SVM-LOMETS collects consensus contact predictions from multiplethreading templates. We test both methods on the same set of554 proteins which are categorized into ‘Easy’,‘Medium’, ‘Hard’ and ‘Very Hard’targets based on the evolutionary and structural distance betweentemplates and targets. For the Easy and Medium targets, SVM-LOMETSobviously outperforms SVM-SEQ; but for the Hard and Very Hardtargets, the accuracy of the SVM-SEQ predictions is higher thanthat of SVM-LOMETS by 12–25%. If we combine the SVM-SEQand SVM-LOMETS predictions together, the total number of correctlypredicted contacts in the Hard proteins will increase by morethan 60% (or 70% for the long-range contact with a sequenceseparation 24), compared with SVM-LOMETS alone. The advantageof SVM-SEQ is also shown in the CASP7 free modeling targetswhere the SVM-SEQ is around four times more accurate than SVM-LOMETSin the long-range contact prediction. These data demonstratethat the state-of-the-art sequence-based contact predictionhas reached a level which may be helpful in assisting tertiarystructure modeling for the targets which do not have close structuretemplates. The maximum yield should be obtained by the combinationof both sequence- and template-based predictions. Contact: yzhang{at}ku.edu Supplementary information: Supplementary data are availableat Bioinformatics online. Associate Editor: Anna Tramontano     

Recalling Taste Intensities in Sweetened and Salted Liquids

The effect of training on recalling taste intensities over 6weeks was studied using an ad libitum mixing procedure. Subjectstasted sweet and salty standards labeled as ‘weak’and ‘strong’ (3 and 8% sucrose in redcurrant juice;0.4 and 1.2% NaCl in beef broth). They subsequently mixed unsweetenedand sweetened juice, and unsalted and salted broth, to producetaste intensities that corresponded to the standards. A minimumtraining (MT) group (n = 13) produced comparison stimuli bytasting and directly comparing with standards in one sessiononly; an extensive training (ET) group (n = 13) did this insix sessions before producing comparison stimuli based on memoryonly at 1 h, 1 day, 1 week and 6 weeks. An upward bias (chemicallydetermined concentrations of comparison stimuli exceeding thoseof standards) occurred at 1 day or 1 week in MT subjects for‘weak’ and ‘strong’ sweetness, and for‘strong’ saltiness, and sustained thereafter. Theupward tendency was also observed in ET subjects but was significantonly for ‘strong’ sweetness. It is important torecognize memory effects such as the one described, as theyaffect food perceptions and can be a major source of bias insensory food research. Chem. Senses 21: 29–34, 1996. ³Current address: Psychonomics Department, Utrecht University,Heidelberglaan 2, 3584 CS Utrecht, The Netherlands     

Reversal of hyposmia in laryngectomized patients

To assess the degree to which the olfactory deficit associatedwith laryngectomy is simply due to the loss of nasal airflow,17 laryngectomees were fitted with a device (larynx bypass)which allowed them to produce approximately normal sniffs. Detectionthresholds were determined for two odorants, vanillin (reportedlyexcites only the olfactory nerve) and ammonia (a strong trigeminalirritant). Without the bypass nine patients detected neitherodorant. The others, who could manoeuver somewhat more vigorousnasal airflows, detected the odorants but only half had ‘normal’thresholds. In this latter group there was a tendency for decreasingdetection thresholds with increasing postoperative years. Withthe bypass all 17 patients achieved ‘normal’ ammoniathresholds whereas 10 achieved ‘normal’ vanillinthresholds. Thus, the loss of nasal airflow is a major contributorto the olfactory deficit of laryngectomy, and it may be theonly contributor for trigeminal irritants like ammonia. On theother hand, for non-trigeminal stimuli like vanillin other factorsseem to be involved.     

Effects of Flooding and Drainage and their Alternation on the Growth and Uptake of Nutrients by Rice (Oryza sativa L., indica, var. IR-8)

Continuous flooding of the soil (‘flooded’ treatment)gave best growth of IR-8 variety of rice whereas soil drainedfor 4 weeks and then flooded for 8 (‘drained and flooded’treatment) resulted in poorest growth and chlorotic plants.Plants grown in the continuously drained soil (‘drained’treatment) and those in the soil flooded for 4 weeks and thendrained for 8 (‘flooded and drained’ treatment)showed intermediate growth. There were no differences in therelative water content of plants growing in the various treatments.Analyses of plant tissues showed that a consideration of therelative concentration of Fe, Mn, and P in the shoots is mostclosely related to the performance of rice under various culturalconditions. An increase in the concentration of Fe in the planttissues following flooding was correlated with the best growth(‘flooded’ treatment) unless it was accompaniedby high level of Mn (as in the ‘drained and flooded’treatment) which may have proved toxic, e.g. by interferencewith Fe metabolism as was evidenced by chlorosis. Measurementsof oxidation-reduction potentials, oxygen diffusion rates, andthe concentration of exchangeable and soluble Fe and Mn in thesoils have shown that the ‘drained and flooded’treatment caused the most extreme reducing conditions. Floodingaccompanied by the development of extreme reducing conditionsled to a greater accumulation of Mn in the shoots (‘drainedand flooded’ treatment) whereas flooding accompanied bythe maintenance of oxidizing conditions (‘flooded’treatment) resulted in a lower uptake of Mn. Growth of riceplants for 4 weeks in the drained soil did not fit them forthe reduced conditions which developed during subsequent flooding(‘drained and flooded’ treatment).     

Developmental Genetics and Morphological Evolution of Flowering Plants, Especially Bladderworts (Utricularia): Fuzzy Arberian Morphology Complements Classical Morphology

This review compares new developmental models on flowering andother vascular plants with evolutionary hypotheses formulatedby Agnes Arber (1879–1960) and like-minded botanists.Special emphasis is laid on philosophical basics such as perspectivism,pluralism about evolutionary modelling, continuum way of thinking,and fuzzy logic. Arber's perspective is best labelled as F uzzyA rberian M orphology (FAM Approach). Its proponents (‘FAMmers’)treat structural categories (e.g. ‘roots’, ‘shoots’,‘stems’, ‘leaves’, ‘stipules’)in vascular plants as concepts with fuzzy borderlines allowingintermediates (including transitional forms, developmental mosaics).The FAM Approach complements Cla ssical Plant M orphology (ClaMApproach), which is the traditional approach in botany. ClaMproponents (‘ClaMmers’) postulate that the structuralcategories of vascular plants are regarded as concepts withclear-cut borderlines and without intermediates. However, duringthe evolution of vascular plants, the root-shoot distinctionand the stem-leaf distinction have become blurred several timesdue to developmental changes, resulting in organs with uniquecombinations of features. This happened, for example, in thebladderworts (Utricularia, Lentibulariaceae). When focusingon the ‘leaf’, the FAM Approach is identical toArber's ‘partial-shoot theory of the leaf’ and Sinha's‘leaf shoot continuum model’. A compound leaf canrepeat the developmental pathway of the whole shoot, at leastto some degree. For example, compound leaves of Chisocheton(Meliaceae)with indeterminate apical growth and three-dimensional branchingmay be seen as developmental mosaics sharing some growth processeswith whole shoots! We focus here on the FAM Approach becausethis perspective is especially promising for developmental geneticistsstudying flowering and other vascular plants. Copyright 2001Annals of Botany Company Review, body plan, developmental mosaics, leaf development, history of botany, homeosis, homeotic genes, Lentibulariaceae, morphological evolution, process morphology, stipules, Utricularia, flowering plants     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

Dimorphism and Monomorphism in the Plumbaginaceae: II. Pollen and Stigmata In the Genus Limonium

A survey of pollen- and stigma-dimorphism and monomorphism inthe genus Limonium (as understood at present) reveals considerableheterogeneity which is useful for the solution of taxonomic,phylogenetic, and phytogeographic problems. Two main pollen types (A and B) and two main stigma types (coband papillate) occur in the genus. Capitate stigmata also occur. ‘Type A’ pollen has frequently been found in conjunctionwith ‘papillate’ stigmata as a secondarily monomorphic(self-compatible) combination and this must have arisen at leastfour times in the genus as well as in Armeria. ‘Type B’pollen and ‘cob’ stigmata are recorded togetherfor the first time (also as a secondarily monomorphic, self-compatiblecombination) in L. echioides. Apomixis, already discovered insubsections Densiflorae and Dissitiflorae, has been found inL. cosyrense of the subsection Steirocladae. The taxonomic and phylogenetic significance of the facts indiscussed.     

The Polarity of the Cell-wall of Valonia

Further evidence is presented to show that the systems of orientationof cellulose fibrils in the cell-walls of Valonia and Dictyosphaeriamay be described by reference to two ‘poles’ uponwhich these orientation systems converge. The ‘poles’are real structural features of the wall.     

The Control of Flowering in Wheat and Barley: What Recent Advances in Molecular Genetics Can Reveal

The combined forces of developmental biologists, studying primordiuminitiation at the stem apex, and mathematical modellers, developingsimulations of crop growth and development, have brought aboutconsiderable advances in the understanding of the control offlowering in wheat and barley. Nevertheless, there are stillmajor gaps in this understanding including: what determinesthe basic rate of development (magnitude of the phyllochronor plastochron); how temperature and photoperiod interact tobring about the transition from vegetative to reproductive development;and how flowering occurs eventually in the absence of inductiveconditions. Although geneticists have tended to measure cerealflowering in terms of ‘days from sowing or emergence toheading’, results of studies using aneuploids and molecularmarkers are compatible with the roles for photoperiod and low-temperaturevernalization established in purely-physiological or developmentalinvestigations. They have also revealed the existence of ‘earlinessperse’loci, whose detailed roles have yet to be established.Progress towards isolating and characterizing wheat and barleyloci is hampered by the poor resolution of mapping (locationto a precision of tens of thousands of base pairs). Neitherof these broad approaches promises a rapid resolution of thefactors controlling the induction of flowering. Two expandingareas of molecular genetics now provide potential for greaterunderstanding of cereal flowering. First, the extensive homoeologyamong members of the Gramineae can be employed to establishthe existence and location of genes or quantitative trait lociin rice which correspond to controlling loci in wheat or barley.Since the rice genome is 1/30th of the size of the wheat genome,the accuracy of mapping loci can be much higher, and there isgreater potential for precise location of loci using techniquessuch as chromosome walking. With the ultimate cloning of individualgenes, and the isolation of gene products, the relative rolesof the 20 loci apparently involved in the induction of floweringof wheat could be explored. However, progress in the moleculargenetics ofArabidopsis(the second area) may provide a more rapidroute to understanding the control of flowering in cereals forseveral reasons: its small genome (1/4 that of rice); the likelihoodof extensive homoeology with cereals, in spite of differencesin codon usage between monocots and dicots; the existence ofa wide range of flowering-time mutants; and the control of floralinduction by a similar range of environmental factors includingphotoperiod and low temperature. It is likely that the MCDK(Martinez-Zapater, Coupland, Dean and Koornneef, 1994. In: MeyerowitzEM, Somerville CR.Arabidopsis.New York: Cold Spring Harbor Laboratory,403–433) model, formulated to explain the genetic andenvironmental control of flowering inArabidopsis,could be employedusefully in the formulation of experimental work on floweringin wheat and barley. This paper reviews these issues, payingparticular attention to the significance of ‘earlinessperse’ loci and the ‘constitutive floral pathway’for wheat and barley.Copyright 1998 Annals of Botany Company Wheat, barley, rice,Arabidopsis,flowering, photoperiod, vernalization, genetics, development.     

The Evolution of Plant Body Plans--A Biomechanical Perspective

Defining ‘plants’ inclusively as ‘photosyntheticeukaryotes’, four basic body plans are identifiable amongplant lineages (unicellular, siphonous, colonial and multicellular).All of these body plans occur in most plant lineages, but onlythe multicellular body plan was carried onto land by the embryophytes.Extensive morphological and anatomical homoplasy is evidentamong species with different body plans. This is ascribed tothe facts that the acquisition of nutrients and radiant energyis affected by plant body size, shape and geometry, and that,with the exception of the unicellular body plan, each of theother body plans involves an ‘open and indeterminate’ontogeny capable of modifying body size, shape and geometryregardless of how organized growth is achieved. In terms ofunicellular species, the available data indicate that size-dependentvariations in surface area, metabolic constituents (e.g. photosyntheticpigments), and reproductive rates limit maximum body size innutrient poor habitats or those that change rapidly or unpredictably.This maximum size can be exceeded in more stable niches by eitherthe cooperation of conspecific cells sharing a common extracellularmatrix (i.e. the ‘colonial’ body plan) or by repeatedmitotic cellular division associated with sustained cytoplasmic(symplastic) continuity (i.e. multicellularity). The siphonousplant body plan may have been evolutionarily derived from aunicellular or multicellular ancestral life form. Each of theplant body plans is reviewed in terms of its biomechanical advantagesand disadvantages. Variants of the multicellular body plan,especially those of the Chlorophyta, Charophyta, and Embryophyta,are given special emphasis. Copyright 2000 Annals of BotanyCompany Algae, biomechanics, body plans, body size, embryophytes, evolution, multicellularity, plants