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Mimicry
Kinds of Mimicry Selected AbstractsOf Mimicry and Membership: Africans and the "New World Society"CULTURAL ANTHROPOLOGY, Issue 4 2002James G. Ferguson First page of article [source] Mimicry in plant-parasitic fungiFEMS MICROBIOLOGY LETTERS, Issue 2 2006Henry K. Ngugi Abstract Mimicry is the close resemblance of one living organism (the mimic) to another (the model), leading to misidentification by a third organism (the operator). Similar to other organism groups, certain species of plant-parasitic fungi are known to engage in mimetic relationships, thereby increasing their fitness. In some cases, fungal infection can lead to the formation of flower mimics (pseudoflowers) that attract insect pollinators via visual and/or olfactory cues; these insects then either transmit fungal gametes to accomplish outcrossing (e.g. in some heterothallic rust fungi belonging to the genera Puccinia and Uromyces) or vector infectious spores to healthy plants, thereby spreading disease (e.g. in the anther smut fungus Microbotryum violaceum and the mummy berry pathogen Monilinia vaccinii-corymbosi). In what is termed aggressive mimicry, some specialized plant-parasitic fungi are able to mimic host structures or host molecules to gain access to resources. An example is M. vaccinii-corymbosi, whose conidia and germ tubes, respectively, mimic host pollen grains and pollen tubes anatomically and physiologically, allowing the pathogen to gain entry into the host's ovary via stigma and style. We review these and other examples of mimicry by plant-parasitic fungi and some of the mechanisms, signals, and evolutionary implications. [source] Clinical Vignette: Intraosseous Meningioma,A Mimicry of Paget's Disease?JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2001Kandaswamy Jayaraj No abstract is available for this article. [source] Mimicry and the evolution of premating isolation in Heliconius melpomene LinnaeusJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2004C. D. Jiggins Abstract Ecological divergence can cause speciation if adaptive traits have pleiotropic effects on mate choice. In Heliconius butterflies, mimetic patterns play a role in mate detection between sister species, as well as signalling to predators. Here we show that male butterflies from four recently diverged parapatric populations of Heliconius melpomene are more likely to approach and court their own colour patterns as compared with those of other races. A few exceptions, where males were more attracted to patterns other than their own, suggest that some mimetic patterns are sub-optimal in mate choice. Genotype frequencies in hybrid zones between races of H. melpomene suggest that mating is random, so reinforcement is unlikely to have played a role in intra-specific divergence. In summary, co-evolved divergence of colour pattern and mate preference occurs rapidly and is likely the first step in Heliconius speciation. [source] Mimicry in coral reef fishes: ecological and behavioural responses of a mimic to its modelJOURNAL OF ZOOLOGY, Issue 1 2004Janelle V. Eagle Abstract Mimicry is a widely documented phenomenon in coral reef fishes, but the underlying relationships between mimics and models are poorly understood. Juveniles of the surgeonfish Acanthurus pyroferus mimic the coloration of different pygmy angelfish Centropyge spp. at different locations throughout the geographic range of the surgeonfish, while adopting a common species-specific coloration as adults. This study examines the ecological and behavioural relationships between A pyroferus and one of its models, Centropyge vroliki, in Papua New Guinea. Surgeonfish underwent a transition from the juvenile (mimetic) coloration to the adult (non-mimetic) coloration when they reached the maximum size of the angelfish. As typical of mimic,model relationships, mimic surgeonfish were always less abundant than their model. Spatial variation in the abundance of mimics was correlated with models, while the abundance of adults was not. We show that juvenile surgeonfish gain a foraging advantage by mimicking the angelfish. Mimic surgeonfish were always found within 1,2 m of a similar-sized individual of C. vroliki with which they spent c. 10% of their time in close association. When in association with angelfish, juvenile surgeonfish exhibited an increase of c. 10% in the amount of time spent feeding compared to when they were alone. This foraging benefit seems to be explained by reduced aggression by the territorial damselfish Plectroglyphidon lacrymatus, which dominates the reef crest habitat. While adult A. pyroferus and all other surgeonfish were aggressively displaced from damselfish territories, mimic surgeonfish and their models were attacked less frequently and were not always displaced. Stomach contents analysis showed that the diet of C. vroliki differed substantially from P. lacrymatus, while that of A. pyroferus was more similar to the damselfish. We hypothesize that mimics deceive damselfish as to their diet in order to gain access to food supplies in defended areas. [source] Genetic continuity of brood-parasitic indigobird speciesMOLECULAR ECOLOGY, Issue 5 2005KRISTINA M. SEFC Abstract Speciation in brood-parasitic indigobirds (genus Vidua) is a consequence of behavioural imprinting in both males and females. Mimicry of host song by males and host fidelity in female egg laying result in reproductive isolation of indigobirds associated with a given host species. Colonization of new hosts and subsequent speciation require that females occasionally lay eggs in the nests of novel hosts but the same behaviour may lead to hybridization when females parasitize hosts already associated with other indigobird species. Thus, retained ancestral polymorphism and ongoing hybridization are two alternative explanations for the limited genetic differentiation among indigobird species. We tested for genetic continuity of indigobird species using mitochondrial sequences and nuclear microsatellite data. Within West Africa and southern Africa, allopatric populations of the same species are generally more similar to each other than to sympatric populations of different species. Likewise, a larger proportion of genetic variation is explained by differences between species than by differences between locations in alternative hierarchical amovas, suggesting that the rate of hybridization is not high enough to homogenize sympatric populations of different species or prevent genetic differentiation between species. Broad sharing of genetic polymorphisms among species, however, suggests that some indigobird species trace to multiple host colonization events in space and time, each contributing to the formation of a single interbreeding population bound together by songs acquired from the host species. [source] Mimicry of dimerization by synthetic peptides designed to target homologous regions of proteinsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2003Donard S. Dwyer Abstract Rapid progress in sequencing various genomes has highlighted the need for the development of biochemical reagents for the detection of thousands of expressed gene products. The magnitude of this detection problem exceeds current technical capabilities. In an attempt to address this shortcoming, a novel approach has been developed called mimicry of dimerization. Peptide tags have been designed to bind to a specific region of parvalbumin on the basis of amino acid sequence homology with this segment. Multivalent ligands were produced by coupling the synthetic peptides to activated dextran polymers and binding was assessed by chemiluminescence of enhanced avidity reactions using a high density of target protein at the binding surface. Binding of the peptide ligands to parvalbumin was strongest under assay conditions that enriched for native monomeric protein and was affected by pH, temperature and solvent conditions. The results suggest that it should be possible to develop specific reagents for tagging proteins on the basis of sequence and secondary structure information. [source] Mimicry of Breast CarcinomaTHE BREAST JOURNAL, Issue 3 2006Ho-Heng Tian MBBS, MMed (Surg), MRCS (Edin) No abstract is available for this article. [source] Voluntary Association in Public Goods Experiments: Reciprocity, Mimicry and Efficiency,THE ECONOMIC JOURNAL, Issue 506 2005Talbot Page We find that a process of voluntary association where individuals express a preference about whom they want to be associated with can create strong incentives to increase efficiency and contributions in provision of a public good. This process of endogenous group formation perfectly sorted contributions by the order of group formation. Comparison of middle and last period behaviour suggests that a majority of the subject population are conditional cooperators, with a minority of monetary payoff maximisers. The experiment illustrates that under favourable conditions, where the opportunities of entry and exit are symmetrically balanced, a process of voluntary association can mitigate the free-rider problem. [source] ORIGINAL ARTICLE: Murine Monoclonal Antibody 26 Raised Against Tetanus Toxoid Cross-Reacts with ,2 -Glycoprotein I: Its Characteristics and Role in Molecular MimicryAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2009Aleksandra Inic-Kanada Problem, Studies on experimental antiphospholipid syndrome (APS) models proved that molecular mimicry between plasma protein ,2 -glycoprotein I (,2GPI) and structure within micro-organisms or their products, might be a cause for experimental APS. Considering the heterogeneity of polyclonal antiphospholipid antibodies (aPLs), it is important to define the precise characteristics of pathogenic aPLs. To avoid the influence of polyclonality and to further analyse the connection between molecular mimicry and APS, we produced monoclonal antibodies (MAbs) against tetanus toxoid (TTd) and tested their reactivity against ,2GPI. Method of study, In this report, we analysed the characteristics of MAb26 raised against TTd and cross-reactive with ,2GPI: its binding properties in various in vitro immunoassays, its specific interactions with surface epitopes expressed on apoptotic cells and its role in vivo. Results, We have demonstrated that MAb26: (i) binds ,2GPI being immobilized on an appropriate surface: irradiated polystyrene plates, non-irradiated plates pre-coated with anionic phospholipids and polyvinylidene fluoride membrane; (ii) binds specifically to apoptotic but not to viable cells and the binding is ,2GPI-dependent; and (iii) induces a pathologic pregnancy outcome when passively injected into BALB/c mice. Conclusion, This study concluded that certain subpopulations of antibodies raised against TTd and cross-reactive with ,2GPI, because of the molecular mimicry mechanism, could have pathologic potential. [source] Vascular Mimicry of Granulosa Cells: a New Concept of Corpeus Luteum Development?ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005R. M. Hirschberg So far, it was generally accepted that newly formed blood vessels are exclusively comprised of endothelial cells, and complemented by pericyte and myocyte recruitment during vessel maturation. Accordingly, participation of non-endothelial cells in the formation of blood vessels has rarely been suggested. Recently, evidence supporting the existence of tumour vessels lined by non-endothelial cells has emerged. Consequently, the concept of the inherent capacity of non-endothelial cells to behave like endothelial cells has been discussed for tumours, and this pathomechanism has been termed vascular mimicry. The corpus luteum is one of the most intensely vascularized tissues, and angiogenesis in the corpus luteum is more effective than in highly malignant tumours. Our results indicate active involvement of granulosa cells in luteal angiogenesis, and the aim of this study was to shed more light on this exciting prospect. The study was based on cultured granulosa cells isolated from the bovine ovary in different stages of follicle maturation. Morphology of angiogenic granulosa cells was studied by phase contrast, transmission electron and scanning electron microscopy. Expression of angiogenesis-regulating factors and their receptors was demonstrated by polymerase chain reaction (RT-PCR). Cultured granulosa cells underwent changes reminiscent of endothelial angiogenesis, i.e., migration, proliferation, differentiation and three-dimensional organization, and expressed angiogenesis-regulating factors and their receptors. Our results suggest a tight regulatory and structural association of endothelial and granulosa cells in luteal angiogenesis, suggesting physiological vascular mimicry in the ovary. [source] Functional Mimicry of an Anti-idiotypic Antibody to Nominal Antigen on Cellular ResponseCANCER SCIENCE, Issue 1 2002Jie Ma One concept for immune therapy of cancer involves induction of antigen mimic antibodies to trigger the immune system into a response against the tumor cells. Anti-idiotypic antibodies (Ab2) directed against the antigen-combining site of other antibodies (Ab1) may functionally and even structurally mimic antigen and induce anti-anti-idiotypic immune response. We report here the generation of murine monoclonal antibody (mAb) WJ02 (Ab2) raised against the murine monoclonal immunoglobulin MJ01 (Ab1), which defines ovarian cancer antigen CA125. In enzyme immunoassays the binding of Ab2 to the variable region of Ab1 could be inhibited by CA125. In addition, the mimicry of mAb WJ02 to CA125 on cellular immune response was detected by human peripheral blood cells. The T cells primed by mAb WJ02 or CA125 proliferated in the presence of CA125 or mAb WJ02, respectively. Furthermore, T cells specific to mAb WJ02 could lyse ovarian cancer cells OVCAR-3 that express CA125. Finally, we proved that a patient immunized with mAb MJ01 could induce T cells that recognize mAb WJ02. In summary, we conclude that mAb WJ02 mimics CA125 on cellular response and such functional mimicry is one of the most important criteria to select Ab2 for cancer therapy. [source] Structure-Based Synthetic Mimicry of Discontinuous Protein Binding Sites: Inhibitors of the Interaction of Mena EVH1 Domain with Proline-Rich LigandsCHEMBIOCHEM, Issue 8 2006Cornelia Hunke Dr. Abstract The Mena EVH1 domain, a protein-interaction module involved in actin-based cell motility, recognizes proline-rich ligand motifs, which are also present in the sequence of the surface protein ActA of Listeria monocytogenes. The interaction of ActA with host Mena EVH1 enables the bacterium to actively recruit host actin in order to spread into neighboring cells. Based on the crystal structure of Mena EVH1 in complex with a polyproline peptide ligand, we have generated a range of assembled peptides presenting the Mena EVH1 fragments that make up its discontinuous binding site for proline-rich ligands. Some of these peptides were found to inhibit the interaction of Mena EVH1 with the ligand pGolemi. One of them was further characterized at the level of individual amino acid residues; this yielded information on the contribution of individual positions of the peptides to the interaction with the ligand and identified sites for future structure optimization. [source] THE EFFECT OF ALTERNATIVE PREY ON THE DYNAMICS OF IMPERFECT BATESIAN AND MÜLLERIAN MIMICRIESEVOLUTION, Issue 6 2004Leena Lindström Abstract Both Batesian and Müllerian mimicries are considered classical evidence of natural selection where predation pressure has, at times, created a striking similarity between unrelated prey species. Batesian mimicry, in which palatable mimics resemble unpalatable aposematic species, is parasitic and only beneficial to the mimics. By contrast, in classical Müllerian mimicry the cost of predators' avoidance learning is shared between similar unpalatable co-mimics, and therefore mimicry benefits all parties. Recent studies using mathematical modeling have questioned the dynamics of Müllerian mimicry, suggesting that fitness benefits should be calculated in a way similar to Batesian mimicry; that is, according to the relative unpalatability difference between co-mimics. Batesian mimicry is very sensitive to the availability of alternative prey, but the effects of alternative prey for Müllerian dynamics are not known and experiments are rare. We designed two experiments to test the effect of alternative prey on imperfect Batesian and Müllerian mimicry complexes. When alternative prey were scarce, imperfect Batesian mimics were selected out from the population, but abundantly available alternative prey relaxed selection against imperfect mimics. Birds learned to avoid both Müllerian models and mimics irrespective of the availability of alternative prey. However, the rate of avoidance learning of models increased when alternative prey were abundant. This experiment suggests that the availability of alternative prey affects the dynamics of both Müllerian and Batesian mimicry, but in different ways. [source] A challenge for regenerative medicine: Proper genetic programming, not cellular mimicryDEVELOPMENTAL DYNAMICS, Issue 12 2007Angie Rizzino Abstract Recent progress in stem cell biology and the reprogramming of somatic cells to a pluripotent phenotype has generated a new wave of excitement in regenerative medicine. Nonetheless, efforts aimed at understanding transdifferentiation, dedifferentiation, and the plasticity of cells, as well as the ability of somatic cells to be reprogrammed, has raised as many questions as those that have been answered. This review proffers the argument that many reports of transdifferentiation, dedifferentiation, and unexpected stem cell plasticity may be due to aberrant processes that lead to cellular look-alikes (cellular mimicry). In most cases, cellular look-alikes can now be identified readily by monitoring gene expression profiles, as well as epigenetic modifications of DNA and histone proteins of the cells involved. This review further argues that progress in regenerative medicine will be significantly hampered by failing to address the issue of cellular look-alikes. Developmental Dynamics 236:3199,3207, 2007. © 2007 Wiley-Liss, Inc. [source] Viral infections as potential triggers of type 1 diabetesDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 3 2007Nienke van der Werf Abstract During the last decades, the incidence of type 1 diabetes (T1D) has increased significantly, reaching percentages of 3% annually worldwide. This increase suggests that besides genetical factors environmental perturbations (including viral infections) are also involved in the pathogenesis of T1D. T1D has been associated with viral infections including enteroviruses, rubella, mumps, rotavirus, parvovirus and cytomegalovirus (CMV). Although correlations between clinical presentation with T1D and the occurrence of a viral infection that precedes the development of overt disease have been recognized, causalities between viruses and the diabetogenic process are still elusive and difficult to prove in humans. The use of experimental animal models is therefore indispensable, and indeed more insight in the mechanism by which viruses can modulate diabetogenesis has been provided by studies in rodent models for T1D such as the biobreeding (BB) rat, nonobese diabetic (NOD) mouse or specific transgenic mouse strains. Data from experimental animals as well as in vitro studies indicate that various viruses are clearly able to modulate the development of T1D via different mechanisms, including direct ,-cell lysis, bystander activation of autoreactive T cells, loss of regulatory T cells and molecular mimicry. Data obtained in rodents and in vitro systems have improved our insight in the possible role of viral infections in the pathogenesis of human T1D. Future studies will hopefully reveal which human viruses are causally involved in the induction of T1D and this knowledge may provide directions on how to deal with viral infections in diabetes-susceptible individuals in order to delay or even prevent the diabetogenic process. Copyright © 2007 John Wiley & Sons, Ltd. [source] Low level of cuticular hydrocarbons in a parasitoid of a solitary digger wasp and its potential for concealmentENTOMOLOGICAL SCIENCE, Issue 1 2009Johannes KROISS Abstract Insect cuticular hydrocarbons (CHC) play a role as semiochemicals in many host,parasite systems and chemical mimicry or camouflage is a well-known mechanism of parasites to evade detection by the host. The cuckoo wasp Hedychrum rutilans (Hymenoptera, Chrysididae) is a parasitoid of larvae of the European beewolf Philanthus triangulum (Hymenoptera, Crabronidae). Females chemically mimic the cuticular hydrocarbons of their hosts to avoid detection and countermeasures when entering the host nest for oviposition. Here we report on a possible second mechanism of the chrysidid wasp H. rutilans to evade detection: the amount of CHC/mm2 of cuticle is only approximately one-fifth compared to its beewolf host. Furthermore, we show that surprisingly large amounts of CHC of beewolf females can be found on the walls of the underground nest. Potentially, these hydrocarbons might constitute a background odor against which the cuckoo wasps or their chemical traces have to be perceived by the beewolf. The reduction in the amount of CHC of the cuckoo wasps might be equivalent to a dilution of recognition cues, especially against the background odor of the nest walls, and might provide a means to escape detection within the nest due to "chemical insignificance". [source] Signals and Signal Choices made by the Araneophagic Jumping Spider Portia fimbriata while Hunting the Orb-Weaving Web spiders Zygiella x-notata and Zosis geniculatusETHOLOGY, Issue 7 2000Michael Tarsitano Portia fimbriata is a web-invading araneophagic jumping spider (Salticidae). The use of signal-generating behaviours is characteristic of how P. fimbriata captures its prey, with three basic categories of signal-generating behaviours being prevalent when the prey spider is in an orb web. The predatory behaviour of P. fimbriata has been referred to as aggressive mimicry, but no previous studies have provided details concerning the characteristics of P. fimbriata's signals. We attempt to determine the model signals for P. fimbriata's ,aggressive mimicry' signals. Using laser Doppler vibrometer and the orb webs of Zygiella x-notata and Zosis geniculatus, P. fimbriata's signals are compared with signals from other sources. Each of P. fimbriata's three categories of behaviour makes a signal that resembles one of three signals from other sources: prey of the web spider (insects) ensnared in the capture zone of the web, prey making faint contact with the periphery of the web and large-scale disturbance of the web (jarring the spider's cage). Experimental evidence from testing P. fimbriata with two sizes of lure made from Zosis (dead, mounted in a lifelike posture in standard-size orb web) clarifies P. fimbriata's signal-use strategy: (1) when the resident spider is small, begin by simulating signals from an insect ensnared in the capture zone (attempt to lure in the resident spider); (2) when the resident spider is large, start by simulating signals from an insect brushing against the periphery of the web (keep the resident spider out in the web, but avoid provoking from it a full-scale predatory attack); (3) when walking in the resident spider's web, regardless of the resident spider's size, step toward the spider while making a signal that simulates a large-scale disturbance of the web (mask footsteps with a self-made vibratory smokescreen). [source] Molecular mimicry in innate immunity?EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2008The viral RNA recognition receptor TLR7 accelerates murine lupus Abstract Toll-like receptors (TLR), such as TLR7, were first described as innate pathogen recognition receptors that trigger appropriate antimircrobial immune responses upon exposure to pathogen-associated molecules, e.g. viral ssRNA. In parallel to ongoing studies on TLR-biology, mounting experimental evidence suggests that endogenous RNA-related autoantigens may also activate dendritic cells (DC) and B cells through TLR7. TLR7-mediated DC activation, autoantibody secretion, lymphoproliferation, and autoimmune tissue injury, are frequently observed in various murine models of systemic lupus and lupus nephritis. A paper in the current issue of the European Journal of Immunology, provide striking experimental evidence for this concept; the authors show that the Y chromosome-linked autoimmune accelerating (Yaa) translocation from the X-chromosome, consisting of 16 genes including Tlr7, largely mediates the autoimmune phenotype via the duplication of Tlr7. This finding highlights the need to address the significance of TLR7 in human lupus in terms of both genetic risk and as a therapeutic option. See accompanying article: http://dx.doi.org/10.1002/eji.200838138 [source] Structural requirements for initiation of cross-reactivity and CNS autoimmunity with a PLP139,151 mimic peptide derived from murine hepatitis virusEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2006Ludovic Croxford Abstract MS is an autoimmune CNS demyelinating disease in which infection appears to be an important pathogenic factor. Molecular mimicry, the cross-activation of autoreactive T cells by mimic peptides from infectious agents, is a possible explanation for infection-induced autoimmunity. Infection of mice with a non-pathogenic strain of Theiler's murine encephalomyelitis virus (TMEV) engineered to express an epitope from Haemophilus influenzae (HI) sharing 6/13 amino acids with the dominant proteolipid protein (PLP) epitope, PLP139,151, can induce CNS autoimmune disease. Here we demonstrate that another PLP139,151 mimic sequence derived from murine hepatitis virus (MHV) which shares only 3/13 amino acids with PLP139,151 can also induce CNS autoimmune disease, but only when delivered by genetically engineered TMEV, not by immunization with the MHV peptide. Further, we demonstrate the importance of proline at the secondary MHC class,II contact residue for effective cross-reactivity, as addition of this amino acid to the native MHV sequence increases its ability to cross-activate PLP139,151 -specific autoreactive T cells, while substitution of proline in the HI mimic peptide has the opposite effect. This study describes a structural requirement for potential PLP139,151 mimic peptides, and provides further evidence for infection-induced molecular mimicry in the pathogenesis of autoimmune disease. [source] Living with a child with a severe orofacial handicap: experiences from the perspectives of parentsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003Ulrika Trulsson Orofacial functions include competences/abilities such as eating, breathing, speech/language, mimicry, as well as oral health, and disturbances are common in children with rare disorders. To describe parental experiences of orofacial function and needs in children with rare disorders, in-depth interviews focusing on orofacial function were carried out with 14 parents. Interviews were transcribed verbatim and analysed in open, axial (theoretical) and selective coding processes according to Grounded Theory. Two core categories emerged from data in the analysis: ,the vulnerable family' and ,support perceived from others'. The data indicated the importance of a balance between these two core categories: the strain caused by living in a family with a child with a severe disability/handicap, and the availability of perceived support from caregivers and significant others. This balance was necessary for the parents in developing self-reliance and in reconciling themselves to their life situations. Parents described orofacial dysfunction in terms of feeding and communication problems, needs for orthodontic treatment to reduce risk of trauma or improve chewing, and drooling. Oral health issues such as dental caries and gingivitis were not mentioned. Five aspects of good professional attitude were recognized: respect, involvement, continuity, knowledge, and availability. [source] Mimicking disliked others: Effects of a priori liking on the mimicry-liking linkEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 5 2010Mariëlle Stel The sharing of bodily states elicits in mimicker and mimickee corresponding conceptualisations, which facilitates liking. There are many studies showing the relatedness of mimicry and liking. However, the mimicry-liking link has not been investigated under conditions in which the mimickee is liked or disliked a priori. In two studies, we examined moderating effects of a priori liking on the mimicry-liking link. Liking was measured via self-report measures (Studies 1 and 2) and behavioural measures using a virtual environment technology (Study 2). Results showed that when participants intentionally mimicked a disliked person, liking for that person was not improved, whereas when participants mimicked a liked person, liking for that person increased. These effects were shown to be mediated by affiliation. These studies not only provided further evidence of a link between mimicry and liking, but also demonstrated that this relationship is moderated by a priori liking. Copyright © 2009 John Wiley & Sons, Ltd. [source] THE PHYLOGENETIC PATTERN OF SPECIATION AND WING PATTERN CHANGE IN NEOTROPICAL ITHOMIA BUTTERFLIES (LEPIDOPTERA: NYMPHALIDAE)EVOLUTION, Issue 7 2006Chris D. Jiggins Abstract Species level phylogenetic hypotheses can be used to explore patterns of divergence and speciation. In the tropics, speciation is commonly attributed to either vicariance, perhaps within climate-induced forest refugia, or ecological speciation caused by niche adaptation. Mimetic butterflies have been used to identify forest refugia as well as in studies of ecological speciation, so they are ideal for discriminating between these two models. The genus Ithomia contains 24 species of warningly colored mimetic butterflies found in South and Central America, and here we use a phylogenetic hypothesis based on seven genes for 23 species to investigate speciation in this group. The history of wing color pattern evolution in the genus was reconstructed using both parsimony and likelihood. The ancestral pattern for the group was almost certainly a transparent butterfly, and there is strong evidence for convergent evolution due to mimicry. A punctuationist model of pattern evolution was a significantly better fit to the data than a gradualist model, demonstrating that pattern changes above the species level were associated with cladogenesis and supporting a model of ecological speciation driven by mimicry adaptation. However, there was only one case of sister species unambiguously differing in pattern, suggesting that some recent speciation events have occurred without pattern shifts. The pattern of geographic overlap between clades over time shows that closely related species are mostly sympatric or, in one case, parapatric. This is consistent with modes of speciation with ongoing gene flow, although rapid range changes following allopatric speciation could give a similar pattern. Patterns of lineage accumulation through time differed significantly from that expected at random, and show that most of the extant species were present by the beginning of the Pleistocene at the latest. Hence Pleistocene refugia are unlikely to have played a major role in Ithomia diversification. [source] MULTILOCUS ANALYSES OF ADMIXTURE AND INTROGRESSION AMONG HYBRIDIZING HELICONIUS BUTTERFLIESEVOLUTION, Issue 6 2006Marcus R. Kronforst Abstract Introgressive hybridization is an important evolutionary process and new analytical methods provide substantial power to detect and quantify it. In this study we use variation in the frequency of 657 AFLP fragments and DNA sequence variation from 15 genes to measure the extent of admixture and the direction of interspecific gene flow among three Heliconius butterfly species that diverged recently as a result of natural selection for Müllerian mimicry, and which continue to hybridize. Bayesian clustering based on AFLP genotypes correctly delineated the three species and identified four H. cydno, three H. pachinus, and three H. melpomene individuals that were of mixed ancestry. Gene genealogies revealed substantial shared DNA sequence variation among all three species and coalescent simulations based on the Isolation with Migration (IM) model pointed to interspecific gene flow as its cause. The IM simulations further indicated that interspecific gene flow was significantly asymmetrical, with greater gene flow from H. pachinus into H. cydno (2Nm 5 4.326) than the reverse (2Nm 5 0.502), and unidirectional gene flow from H. cydno and H. pachinus into H. melpomene (2Nm 5 0.294 and 0.252, respectively). These asymmetries are in the directions expected based on the genetics of wing patterning and the probability that hybrids of various phenotypes will survive and reproduce in different mimetic environments. This empirical demonstration of extensive interspecific gene flow is in contrast to a previous study which found little evidence of gene flow between another pair of hybridizing Heliconius species, H. himera and H. erato, and it highlights the critical role of natural selection in maintaining species diversity. Furthermore, these results lend support to the hypotheses that phenotypic diversification in the genus Heliconius has been fueled by introgressive hybridization and that reinforcement has driven the evolution of assortative mate preferences. [source] THE EFFECT OF ALTERNATIVE PREY ON THE DYNAMICS OF IMPERFECT BATESIAN AND MÜLLERIAN MIMICRIESEVOLUTION, Issue 6 2004Leena Lindström Abstract Both Batesian and Müllerian mimicries are considered classical evidence of natural selection where predation pressure has, at times, created a striking similarity between unrelated prey species. Batesian mimicry, in which palatable mimics resemble unpalatable aposematic species, is parasitic and only beneficial to the mimics. By contrast, in classical Müllerian mimicry the cost of predators' avoidance learning is shared between similar unpalatable co-mimics, and therefore mimicry benefits all parties. Recent studies using mathematical modeling have questioned the dynamics of Müllerian mimicry, suggesting that fitness benefits should be calculated in a way similar to Batesian mimicry; that is, according to the relative unpalatability difference between co-mimics. Batesian mimicry is very sensitive to the availability of alternative prey, but the effects of alternative prey for Müllerian dynamics are not known and experiments are rare. We designed two experiments to test the effect of alternative prey on imperfect Batesian and Müllerian mimicry complexes. When alternative prey were scarce, imperfect Batesian mimics were selected out from the population, but abundantly available alternative prey relaxed selection against imperfect mimics. Birds learned to avoid both Müllerian models and mimics irrespective of the availability of alternative prey. However, the rate of avoidance learning of models increased when alternative prey were abundant. This experiment suggests that the availability of alternative prey affects the dynamics of both Müllerian and Batesian mimicry, but in different ways. [source] Helicobacter pylori, T cells and cytokines: the "dangerous liaisons"FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2005Mario Milco D'Elios Abstract Helicobacter pylori infection is the major cause of gastroduodenal pathologies, but only a minority of infected patients develop chronic and life threatening diseases, as peptic ulcer, gastric cancer, B-cell lymphoma, or autoimmune gastritis. The type of host immune response against H. pylori is crucial for the outcome of the infection. A predominant H. pylori -specific Th1 response, characterized by high IFN-,, TNF-,, and IL-12 production associates with peptic ulcer, whereas combined secretion of both Th1 and Th2 cytokines are present in uncomplicated gastritis. Gastric T cells from MALT lymphoma exhibit abnormal help for autologous B-cell proliferation and reduced perforin- and Fas,Fas ligand-mediated killing of B cells. In H. pylori -infected patients with autoimmune gastritis cytolytic T cells infiltrating the gastric mucosa cross-recognize different epitopes of H. pylori proteins and H+K+ ATPase autoantigen. These data suggest that peptic ulcer can be regarded as a Th1-driven immunopathological response to some H. pylori antigens, whereas deregulated and exhaustive H. pylori -induced T cell-dependent B-cell activation can support the onset of low-grade B-cell lymphoma. Alternatively, H. pylori infection may lead in some individuals to gastric autoimmunity via molecular mimicry. [source] Mimicry in plant-parasitic fungiFEMS MICROBIOLOGY LETTERS, Issue 2 2006Henry K. Ngugi Abstract Mimicry is the close resemblance of one living organism (the mimic) to another (the model), leading to misidentification by a third organism (the operator). Similar to other organism groups, certain species of plant-parasitic fungi are known to engage in mimetic relationships, thereby increasing their fitness. In some cases, fungal infection can lead to the formation of flower mimics (pseudoflowers) that attract insect pollinators via visual and/or olfactory cues; these insects then either transmit fungal gametes to accomplish outcrossing (e.g. in some heterothallic rust fungi belonging to the genera Puccinia and Uromyces) or vector infectious spores to healthy plants, thereby spreading disease (e.g. in the anther smut fungus Microbotryum violaceum and the mummy berry pathogen Monilinia vaccinii-corymbosi). In what is termed aggressive mimicry, some specialized plant-parasitic fungi are able to mimic host structures or host molecules to gain access to resources. An example is M. vaccinii-corymbosi, whose conidia and germ tubes, respectively, mimic host pollen grains and pollen tubes anatomically and physiologically, allowing the pathogen to gain entry into the host's ovary via stigma and style. We review these and other examples of mimicry by plant-parasitic fungi and some of the mechanisms, signals, and evolutionary implications. [source] Molecular Mimetic Self-Assembly of Colloidal ParticlesADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Zhengwei Mao Abstract This article presents an overview of the current progress in molecular mimetic self-assembly of colloidal particles. Firstly, the recent study of colloidal particles at interfaces is highlighted, underlining the mesoscopic mimicry of the surface activity of amphiphilic molecules using colloidal particles. Secondly, various strategies developed thus far to impart colloidal particles with anisotropy in terms of chemical composition, surface chemistry and particle morphology, which are regarded as mesoscopic atoms and molecules, are reviewed. Thirdly, an overview of the current theoretical and experimental results of using the rules of molecular synthesis and self-assembly to direct self-assembly of colloidal particles is presented. Finally, the experimental challenges associated with molecular mimetic self-assembly of colloidal particles are outlined, giving a rather conservative conclusion of the status quo of this new research field with a very optimistic outlook. [source] Private channel: a single unusual compound assures specific pollinator attraction in Ficus semicordataFUNCTIONAL ECOLOGY, Issue 5 2009Chun Chen Summary 1.,Floral scents have been suggested to play a key role in the obligate pollination mutualism between figs and fig wasps. However, few studies have determined whether pollinator-attractive compounds could alone assure species-specificity (,private channel'), or whether specificity is mediated by more complex ,floral filters', of which scent is only one component. 2.,We examined changes in the floral volatile compounds of Ficus semicordata, a dioecious fig species, during and after pollination using headspace collection and compound identification by Gas Chromatography/Mass Spectrometry (GC/MS). One benzenoid compound, 4-methylanisole, was strongly predominant (94,98%) among the volatile compounds emitted by both male and female receptive figs of F. semicordata, whereas it was totally absent in the volatiles emitted by figs 4 days after pollination, as well as in receptive-stage volatiles emitted by two other sympatric fig species, Ficus racemosa and Ficus hispida. 3.,Bioassays using the specific pollinator of F. semicordata, Ceratosolen gravelyi, in a Y-tube olfactometer showed that 4-methylanisole was attractive to C. gravelyi in a wide range of concentrations (from 1·22 × 10,2 ng/100 ,L to 1·22 × 106ng/100,L). Moreover, chemical blends lacking 4-methylanisole were unattractive to C. gravelyi. These non-active odour sources included volatile compounds emitted by receptive figs of the two other sympatric fig species and volatiles of F. semicordata post-pollination figs. 4.,All these results suggest that 4-methylanisole is the main signal compound in the floral scent of F. semicordata that attracts its obligate pollinator to the host figs at the precise stage required for pollination and oviposition. Furthermore, the high proportion of 4-methylanisole in the odours of receptive figs of both sexes was consistent with the hypothesis of chemical mimicry in dioecious figs. 5.,A simple signal comprised of one compound that is unusual among Ficus and that is an infrequent, usually minor, component of other floral odours, may thus function as a private channel in this specialized obligate mutualism. [source] Examining resistance, accommodation and the pursuit of aspiration in the Indian IT-BPO space: reflections on two case studiesINDUSTRIAL RELATIONS JOURNAL, Issue 2 2010M. N. Ravishankar ABSTRACT This article is based on case studies of two organisations: an India-based information technology (IT) services company and a financial services company located in the UK and India. Although they operate in different sectors and have some notable contrasts, both can be seen as typifying aspects of India's new economy. Our article explores the lived experience of working in this economy,a perspective that has been relatively neglected in the extant literature. Drawing on Homi Bhabha's notions of ambivalence and mimicry, and V. S. Naipaul's powerful illustrations of these concepts in his fiction and non-fiction works, we report on how respondents talked about their aspirations within India's emerging economy, and examine their mobilisation of particular discursive resources as forms of accommodation and resistance to the demands they face at work. [source] | ||||||||||||||||||||||||||||||||||||||||||||||