Intriguing olfactory proteins from the yellow fever mosquito,<Emphasis Type="Italic"> Aedes aegypti</Emphasis>

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.     

Acoustic mirror effect increases prey detection distance in trawling bats

Many different and phylogenetically distant species of bats forage for insects above water bodies and take insects from and close to the surface; the so-called trawling behaviour. Detection of surface-based prey by echolocation is facilitated by acoustically smooth backgrounds such as water surfaces that reflect sound impinging at an acute angle away from the bat and thereby render a prey object acoustically conspicuous. Previous measurements had shown that the echo amplitude of a target on a smooth surface is higher than that of the same target in mid-air, due to an acoustic mirror effect. In behavioural experiments with three pond bats (Myotis dasycneme), we tested the hypothesis that the maximum distances at which bats can detect prey are larger for prey on smooth surfaces than for the same prey in an airborne situation. We determined the moment of prey detection from a change in echolocation behaviour and measured the detection distance in 3D space from IR-video recordings using stereo-photogrammetry. The bats showed the predicted increase in detection distance for prey on smooth surfaces. The acoustic mirror effect therefore increases search efficiency and contributes to the acoustic advantages encountered by echolocating bats when foraging at low heights above smooth water surfaces. These acoustic advantages may have favoured the repeated evolution of trawling behaviour.     

Knowing your enemies: seasonal dynamics of host–social parasite recognition

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.     

Colony size affects division of labour in the ponerine ant<Emphasis Type="Italic"> Rhytidoponera metallica</Emphasis>

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.     

‘Benefit–Cost Analysis’ Of Disaster Mitigation: Application As a Policy And Decision-Making Tool

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.     

Month of birth and life expectancy: role of gender and age in a comparative approach

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.     

Light,timing of biological rhythms,and chronodisruption in man

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.