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Query: UMLS:C0277787 (stigma)
 13,352 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Arabidopsis is believed to be mostly self-pollinated, although several lines of genetic and morphological evidence indicate that insect-mediated outcrossing occurs with at least a low frequency in wild populations. Here, we show that Arabidopsis flowers emit both monoterpenes and sesquiterpenes, potential olfactory cues for pollinating insects. Of the 32 terpene synthase genes in the Arabidopsis genome, 20 were found to be expressed in flowers, 6 of these exclusively or almost exclusively so. Two terpene synthase genes expressed exclusively in the flowers and one terpene synthase gene expressed almost exclusively in the flowers were characterized and found to encode proteins that catalyze the formation of major floral volatiles. A beta-glucuronidase fusion construct with a promoter of one of these genes demonstrated that gene expression was restricted to the sepals, stigmas, anther filaments, and receptacles, reaching a peak when the stigma was receptive to cross pollen. The observation that Arabidopsis flowers synthesize and emit volatiles raises intriguing questions about the reproductive behavior of Arabidopsis in the wild and allows detailed investigations of floral volatile biosynthesis and its regulation to be performed with this model plant system.
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PMID:Biosynthesis and emission of terpenoid volatiles from Arabidopsis flowers. 1256 86

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 (pseudo flowers) 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.
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PMID:Mimicry in plant-parasitic fungi. 1655 49

Spiritual explanations for epilepsy have existed since antiquity and continue to be prevalent in some communities today. While the vast majority of the unfortunate recipients of this understanding are thought to be possessed by evil forces, a few are deemed to be special vessels for divine communication. Here we present the intriguing case of Christina the Astonishing (1150-1224). Christina appears to be unique in the archives of the religious interpretation of epilepsy in that her seizures were understood to represent her willing submission to demonic torments to provide much needed respite for those in purgatory. Thus she provides an ingenious link between the demonic and divine explanations of the disorder. From a medical perspective, the analysis of contemporary accounts of her afflictions provide compelling evidence of status epilepticus, olfactory auras, and probable frontal lobe epilepsy, with frequent secondary generalization. Even more remarkably, the 13th century accounts of Christina's shame and embarrassment and the social stigma associated with her seizures strike a startling contemporary chord.
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PMID:The intriguing case of Christina the Astonishing. 1975 62

Paphiopedilum barbigerum T. Tang et F. T. Wang, a slipper orchid native to southwest China and northern Vietnam, produces deceptive flowers that are self-compatible but incapable of mechanical self-pollination (autogamy). The flowers are visited by females of Allograpta javana and Episyrphus balteatus (Syrphidae) that disperse the orchid's massulate pollen onto the receptive stigmas. Measurements of insect bodies and floral architecture show that the physical dimensions of these two fly species correlate with the relative positions of the receptive stigma and dehiscent anthers of P. barbigerum. These hoverflies land on the slippery centralised wart located on the shiny yellow staminode and then fall backwards through the labellum entrance. They are temporarily trapped in the inflated chamber composed of the interconnected labellum and column. The attractive staminode of P. barbigerum strongly reflects the colour yellow (500-560 nm), a colour preferred innately by most pollen-eating members of the Syrphidae. No scent molecules were detected using GC mass spectrometry analysis, showing that the primary attractant in this system is visual, not olfactory. Pollination-by-deceit in P. barbigerum is contrasted with its congener, P. dianthum, a brood site mimic that is pollinated by ovipositing females of E. balteatus. As the natural rate of fruit set in P. barbigerum (mean 26.3% pooled over three seasons) is lower than that of P. dianthum (mean 58.5% over two seasons), the evolution of false brood sites in some Paphiopedilum spp. should be selectively advantageous as they may provide an increase in the attention and return rates of dependable pollinators to flowers that always lack a reward.
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PMID:Pollination by deceit in Paphiopedilum barbigerum (Orchidaceae): a staminode exploits the innate colour preferences of hoverflies (Syrphidae). 1912 Nov 10

In a variety of personal and professional domains, heavy individuals face stigma associated with their body size. Here we investigate a new method for subtle detection of the negative perceptions consistent with that stigma. In two studies, participants were asked to view images of heavy and thin individuals while smelling substances that, unbeknownst to them, were odorless. Across both studies, the results showed that the substances were perceived to smell worse when they were paired with images of heavy individuals than when they were paired with images of thin individuals. These findings suggest that perceptions of stigmatized individuals can be assessed indirectly through olfactory responses. More generally, they suggest that the effects of weight stigma are broader than previously recognized.
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PMID:What does weight stigma smell like? Cross-modal influence of visual weight cues on olfaction. 2564 89