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- Raguso, Robert A., et al.
(författare)
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Floral biology of North American Oenothera sect. Lavauxia (Onagraceae): Advertisements, rewards, and extreme variation in floral depth
- 2007
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Ingår i: Annals of the Missouri Botanical Garden. - 0026-6493. ; 94:1, s. 236-257
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Tidskriftsartikel (refereegranskat)abstract
- We studied the floral biology of five North American members of Oenothera L. sect. Lavauxia (Spach) Endl. (Onagraceae L.) in field and common greenhouse settings. Oenothera sect. Lavauxia floral morphology ranges from small, cleistogamous flowers (O. flava subsp. flava (A. Nels.) Garrett in Garrett) to sonic of the longest-tubed flowers in North America (O. flava subsp. taraxacoides (Wooton & Standl.) W. L. Wagner). Our goal was to compare qualitative and quantitative aspects of floral advertisement and reward among taxa in section Lavauxia. All taxa are night-blooming and self-compatible, have yellow petals with ultraviolet reflectance, and produce floral scents dominated by nitrogenous compounds and monoterpenes. Methyl nicotinate is present in the fragrances of all taxa of section Lavauxia regardless of flower size or putative mating system. Because this floral volatile is largely absent from other Oenothera species, we hypothesize that it is a synapomorphy for section Lavauxia. The rare O. acutissima W. L. Wagner, which is endemic to the Uintah Mountains, is polymorphic for odors dominated by linalool- or ocimene-derived compounds). Field observations in its type locality in northeastern Utah, U.S.A., revealed frequent floral visitation by crepuscular hawkmoths during the first 1.5 hours after anthesis, a pattern common to O. flava subsp. taraxacoides and other large-flowered Oenothera throughout western North America. Quantitative aspects of floral advertisement (flower size, scent emission) and reward (nectar volume) are dramatically reduced in putatively autogamous taxa (O. flava subsp. flava, O. triloba Nutt.). whereas qualitative aspects (flower color, scent, and nectar chemistry) remain comparable. All taxa could be distinguished through ordination of characters related to flower size, herkogamy. and scent chemistry. Extreme nectar tube length variation across the range of O. flava renders this an excellent model system for measuring the costs and mechanisms of shifts between outcrossing and autogamy.
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| 3. |
- Goyret, Joaquin, et al.
(författare)
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Flexible responses to visual and olfactory stimuli by foraging Manduca sexta: larval nutrition affects adult behaviour
- 2009
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 276:1668, s. 2739-2745
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Tidskriftsartikel (refereegranskat)abstract
- Here, we show that the consequences of deficient micronutrient (beta-carotene) intake during larval stages of Manduca sexta are carried across metamorphosis, affecting adult behaviour. Our manipulation of larval diet allowed us to examine how developmental plasticity impacts the interplay between visual and olfactory inputs on adult foraging behaviour. Larvae of M. sexta were reared on natural (Nicotiana tabacum) and artificial laboratory diets containing different concentrations of beta-carotene (standard diet, low beta-carotene, high beta-carotene and cornmeal). This vitamin-A precursor has been shown to be crucial for photoreception sensitivity in the retina of M. sexta. After completing development, post-metamorphosis, starved adults were presented with artificial feeders that could be either scented or unscented. Regardless of their larval diet, adult moths fed with relatively high probabilities on scented feeders. When feeders were unscented, moths reared on tobacco were more responsive than moths reared on beta-carotene-deficient artificial diets. Strikingly, moths reared on artificial diets supplemented with increasing amounts of beta-carotene (low beta and high beta) showed increasing probabilities of response to scentless feeders. We discuss these results in relationship to the use of complex, multi-modal sensory information by foraging animals.
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| 4. |
- Goyret, Joaquin, et al.
(författare)
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Why do Manduca sexta feed from white flowers? Innate and learnt colour preferences in a hawkmoth
- 2008
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Ingår i: Naturwissenschaften. - : Springer Science and Business Media LLC. - 1432-1904 .- 0028-1042. ; 95:6, s. 569-576
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Tidskriftsartikel (refereegranskat)abstract
- Flower colour is an important signal used by flowering plants to attract pollinators. Many anthophilous insects have an innate colour preference that is displayed during their first foraging bouts and which could help them locate their first nectar reward. Nevertheless, learning capabilities allow insects to switch their colour preferences with experience and thus, to track variation in floral nectar availability. Manduca sexta, a crepuscular hawkmoth widely studied as a model system for sensory physiology and behaviour, visits mostly white, night-blooming flowers lacking UV reflectance throughout its range in the Americas. Nevertheless, the spectral sensitivity of the feeding behaviour of naive moths shows a narrow peak around 450 nm wavelengths, suggesting an innate preference for the colour blue. Under more natural conditions (i.e. broader wavelength reflectance) than in previous studies, we used dual choice experiments with blue- and white-coloured feeders to investigate the innate preference of naive moths and trained different groups to each colour to evaluate their learning capabilities. We confirmed the innate preference of M. sexta for blue and found that these moths were able to switch colour preferences after training experience. These results unequivocally demonstrate that M. sexta moths innately prefer blue when presented against white flower models and offer novel experimental evidence supporting the hypothesis that learning capabilities could be involved in their foraging preferences, including their widely observed attraction to white flowers in nature.
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| 5. |
- Westberg, Lars, 1973, et al.
(författare)
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Colocalization of connexin 36 and corticotropin-releasing hormone in the mouse brain.
- 2009
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Ingår i: BMC neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 10:41
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Gap junction proteins, connexins, are expressed in most endocrine and exocrine glands in the body and are at least in some glands crucial for the hormonal secretion. To what extent connexins are expressed in neurons releasing hormones or neuropeptides from or within the central nervous system is, however, unknown. Previous studies provide indirect evidence for gap junction coupling between subsets of neuropeptide-containing neurons in the paraventricular nucleus (PVN) of the hypothalamus. Here we employ double labeling and retrograde tracing methods to investigate to what extent neuroendocrine and neuropeptide-containing neurons of the hypothalamus and brainstem express the neuronal gap junction protein connexin 36. RESULTS: Western blot analysis showed that connexin 36 is expressed in the PVN. In bacterial artificial chromosome transgenic mice, which specifically express the reporter gene Enhanced Green Fluorescent Protein (EGFP) under the control of the connexin 36 gene promoter, EGFP expression was detected in magnocellular (neuroendocrine) and in parvocellular neurons of the PVN. Although no EGFP/connexin36 expression was seen in neurons containing oxytocin or vasopressin, EGFP/connexin36 was found in subsets of PVN neurons containing corticotropin-releasing hormone (CRH), and in somatostatin neurons located along the third ventricle. Moreover, CRH neurons in brainstem areas, including the lateral parabrachial nucleus, also expressed EGFP/connexin 36. CONCLUSION: Our data indicate that connexin 36 is expressed in subsets of neuroendocrine and CRH neurons in specific nuclei of the hypothalamus and brainstem.
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