| 1. |
- Forsman, Anders, et al.
(författare)
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Maintenance of colour polymorphism in adder populations, Vipera berus L.: a test of a popular hypothesis
- 1987
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Ingår i: Oikos. ; 50, s. 13-16
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Tidskriftsartikel (refereegranskat)abstract
- Accordingt o a currenth ypothesis,t he colourp olymorphismin populationso f the adder,Vipera berus L., is maintained by a thermal superiority of melanistic snakes,which enables them to grow more quickly than normally coloured ones. Since largermales are superior in sexual combats, and larger females get more offspring, thisclearly should favour the melanistic trait. On the other hand, melanistic individualsare believed to suffer a higher predation pressure due to their more conspicuous appearance.T he predictionf rom this hypothesisi s that melanistici ndividualso n averageshould be largert han normali ndividualsi n mixed populations.T his predictionwas tested on adders captured on several small islands in the Stockholm archipelago(N 59°20';E 19°20').N o significantd ifferencew as found in weight, lengtho r weight/length ratio between melanistic and normally coloured male adders. Neither slopenor elevation of the regression lines of length on weight differed. Thus, the hypothesiswas not supported by our data.
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| 2. |
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| 3. |
- Breidbach, Olaf, et al.
(författare)
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Proctolin-immunoreactive neurons persist during metamorphosis of an insect: A developmental study of the ventral nerve cord of Tenebrio molitor(Coleoptera)
- 1989
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Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 257:1, s. 217-225
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Tidskriftsartikel (refereegranskat)abstract
- Proctolin-immunoreactive neurons in all neuromers of the ventral nerve cord of Tenebrio molitor L. have been quantitatively demonstrated and mapped throughout metamorphosis. Each neuromer contains an anterior and a posterior group of neurons with light and dark staining properties as revealed by peroxidase-antiperoxidase labeling. Serial homologous subsets of dark staining neurons with central and peripheral projections have been identified and found to persist during morphogenetic changes from the larva to the adult. Most neurons maintain their topological and structural characteristics throughout metamorphosis. The identified proctolin-immunoreactive neurons exhibit structures similar to those described in other insect species; some may correspond known motoneurons.
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| 4. |
- Ekström, Peter, et al.
(författare)
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Antibodies against retinal photoreceptor‐specific proteins reveal axonal projections from the photosensory pineal organ in teleosts
- 1987
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 265:1, s. 25-33
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Tidskriftsartikel (refereegranskat)abstract
- With the aid of specific antisera to the retinal proteins S‐antigen and α‐transducin and to the rhodopsin apoprotein opsin, we have labeled various cell populations in the pineal organ, parapineal organ, habenular nucleus, and subcommissural organ in two teleost species: the rainbow trout and the European minnow. Although these proteins are associated with photoreceptor functions, not only photoreceptor cells but also the majority of parenchymal cells in the pineal organ were immunoreactive. Immunoreactive cells with dendrite‐ and axonlike processes were observed also in the parapineal organ and the habenular nucleus. Furthermore, S‐antigen‐immunoreactive, long, axonal processes were observed in the pineal organ and could be traced from the pineal organ to the habenular nucleus and to the pretectal area. In the light of recent HRP electron microscopical and immunocytochemical studies we propose (1) that not only the classical pineal photoreceptor cells of poikilothermic vertebrates but also other types of CSF‐contacting neurons may be the phylogenetic ancestors of mammalian pinealocytes, and (2) a close interrelationship between the pineal organ and the limbic system, effectuated by the direct projections from pineal photoreceptors/CSF‐contacting neurons/pinealocytes to the habenular nucleus, and by displaced “pinealocytelike” elements scattered in the habenular nucleus.
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