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941.
Anna K. Hundsdoerfer Jeannette Ndaya Tshibangu Bernhard Wetterauer Michael Wink 《Chemoecology》2005,15(4):261-267
Summary. The larvae of the hawkmoth species Hyles euphorbiae have a conspicuous aposematic colouration and show gregarious behaviour. It has thus been suggested that they sequester phorbol
esters from their food plants which include different species of the genus Euphorbia (Euphorbiaceae) for chemical protection against predators. To test this hypothesis in more detail, we fed larvae an artificial
diet with three doses of 12-tetradecanoyl-phorbol-13-acetate (TPA), then examined the faeces and the larval tissues, such
as integument, haemolymph and gut of the caterpillars for the presence of TPA. In order to determine the ability of the larvae
to detoxify phorbol esters, other larvae were directly injected with a TPA solution and analysed in the same manner. Our study
indicates that the larvae of Hyles euphorbiae do not sequester phorbol esters. Upon oral application TPA was not found in the larval integument or the haemolymph. Instead,
it was mostly metabolised (about 70–90%). Nevertheless, about 10-30% were retained and recovered in the faeces. The larvae
were also able to metabolise and thus detoxify the phorbol ester when TPA was injected directly into the body. These hawkmoth
caterpillars are relatively large and have a gut full of plant material, which they regurgitate into the direction of the
predator when attacked in nature. Since phorbol esters are very potent toxins and irritants, we postulate that the gut content
(and especially the plant slurry disgorged as regurgitant from the anterior gut) alone could be aversive for a potential predator,
even if some metabolism has taken place. Thus, although H. euphorbiae caterpillars do not actively sequester phorbol esters, their aposematic colouration appears to be based on chemical defence
through phorbol esters retained in the gut. 相似文献
942.
Four antennae-specific proteins (AaegOBP1, AaegOBP2, AaegOBP3, and AaegASP1) were isolated from the yellow fever mosquito, Aedes aegypti and their full-length cDNAs were cloned. RT-PCR indicated that they are expressed in female and, to a lesser extent, in male antennae, but not in control tissues (legs). AaegOBP1 and AaegOBP3 showed significant similarity to previously identified mosquito odorant-binding proteins (OBPs) in cysteine spacing pattern and sequence. Two of the isolated proteins have a total of eight cysteine residues. The similarity of the spacing pattern of the cysteine residues and amino acid sequence to those of previously identified olfactory proteins suggests that one of the cysteine-rich proteins (AaegOBP2) is an OBP. The other (AaegASP1) did not belong to any group of known OBPs. Structural analyses indicate that six of the cysteine residues in AaegOBP2 are linked in a similar pattern to the previously known cysteine pairing in OBPs, i.e., Cys-24–Cys-55, Cys-51–Cys-104, Cys-95–Cys-113. The additional disulfide bridge, Cys-38–Cys-125, knits the extended C-terminal segment of the protein to a predicted 2-helix. As indicated by circular dichroism (CD) spectra, the extra rigidity seems to prevent the predicted formation of a C-terminal -helix at low pH.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material. 相似文献
943.
Despite its evolutionary significance, behavioural flexibility of social response has rarely been investigated in insects. We studied a host–social parasite system: the slave-making ant Polyergus rufescens and its host Formica rufibarbis. Free-living host workers from parasitized and from unparasitized areas were compared in their level of aggression against the parasite and alien conspecifics. We expected that a seasonal change would occur in the acceptance threshold of F. rufibarbis workers from a parasitized area towards the parasite, whereas F. rufibarbis workers from an unparasitized area would not show substantial changes connected with the parasites peak in activity (raiding and colony-founding season). The results showed a significant adaptive behavioural flexibility of host species workers and are consistent with the acceptance threshold models (Reeve 1989) prediction that recognition systems are not fixed but context-dependent. In particular, host workers from the unparasitized area were highly aggressive towards the parasite regardless of the season, whereas host workers from the parasitized area significantly increased their aggression towards the parasite during its raiding and colony-founding season. Being able to detect and possibly kill a Polyergus scout searching for host nests can be an effective strategy for a Formica colony to avoid being raided or usurped by a parasite queen. 相似文献
944.
In theory, larger colonies of social insects should have greater colony organisation. While inter-specific comparative studies provide support for this idea, there is little direct intra-specific evidence. We investigated differences in task specialisation between large (>450 workers) and small (<80 workers) colonies of the ponerine ant Rhytidoponera metallica. Observations of individually marked young or old workers revealed greater task specialisation in large colonies. Age polyethism was detected in large but not small colonies. In large colonies, old workers spent significantly more time foraging than young workers did, while young workers spent more time caring for brood. In small colonies, young and old workers spent a similar amount of time foraging and caring for brood. This difference in task allocation patterns in large and small colonies was associated with a difference in contact rates between workers. Workers in small colonies have a lower contact rate between nestmates and a greater variability in time between contacts than workers from large colonies. 相似文献
945.
Philip?T.?GandertonEmail author 《Mitigation and Adaptation Strategies for Global Change》2005,10(3):445-465
Many proponents of disaster mitigation claim that it offers potential benefits in terms of saved lives and property far exceeding
its costs. To provide evidence for this, and to justify the use of public funds, agencies involved in mitigation can use benefit–cost
analysis (BCA). Such analysis, if well done, offers a testable, defensible means of evaluating and comparing projects, helps
decision-makers choose between mitigation projects, and provides a means to assess the way we spend public funds. In this
critical overview of the more contentious issues and latest developments in BCA, I emphasize the pragmatic choices that one
can make in accordance with good practice in project evaluation. 相似文献
946.
Lerchl A 《Die Naturwissenschaften》2004,91(9):422-425
The effects of month of birth (MOB) on life expectancy of a German subpopulation was investigated. Data from people who died in North Rhine Westphalia in the years 1984 (n=188,515) and 1999 (n=188,850) were analyzed. For comparative purposes, all deaths that occurred at an age of <50 years were excluded (1984: 8.4%; 1999: 6.2%). In general, individuals born in May through July had the lowest age at death (1984: 75.27±0.09 years; 1999: 77.58±0.09 years), while those born between October and December had the highest (1984: 75.98±0.08 years; 1999: 78.35±0.09 years), supporting earlier findings. The observed amplitudes (differences between highest and lowest values) were more pronounced in men than in women. When comparing these data of MOB effects on life expectancy with earlier findings in Australia, Austria, Denmark, Ukraine, and the USA, it is evident that a negative correlation exists between the average age at death and the MOB amplitudes. Separate analyses by gender, possible for the data from Germany, the Ukraine, and the USA, revealed a significant negative correlation for men, but not for women. A new hypothesis is therefore presented describing an influence of life quality, as reflected by average life expectancy, on the extent of MOB effects; for example, seasonally variable sensitivities during pregnancy/early childhood. 相似文献
947.
Light,timing of biological rhythms,and chronodisruption in man 总被引:3,自引:2,他引:3
This paper reviews abundant evidence suggesting that causes and course of aging and cancers can be considered as being both light- and rhythm-related. We define chronodisruption as a relevant disturbance of orderly biological rhythms over days and seasons and years in man. Light is the primary external mediator and melatonin a primary internal intermediary of such disturbances, which can result in earlier deaths via premature aging and cancers. We conclude that experimental and epidemiological research can provide further insights into common denominators of these chronic processes and may offer novel and uniform targets for prevention. 相似文献
948.
E. -A. Müller A. Gr?ser P. Kuhbier O. Lawaczeck G. B?hme et al. 《Die Naturwissenschaften》1995,82(12):579-580
949.
950.