No abstract

We studied associations between lifestyle/medical factors and lipid-adjusted serum concentrations of seven polychlorinated biphenyl (PCB) congeners and five chlorinated pesticides/metabolites among 205 Swedish women (54-75 years old). Serum concentrations were significantly associated with age, body mass index, body weight change, diabetes mellitus, consumption of fatty fish, and place of residence. The findings suggest that lifestyle/medical factors may confound results in epidemiologic studies when they are related to both serum concentrations and disease. Moreover, disease itself may influence serum concentrations of some organochlorines, as indicated by the negative associations between recent weight change and serum concentrations of some PCB congeners, p,p -dichlorodiphenyldichloroethylene (DDE), and hexachlorobenzene (HCB) and the positive association between diabetes mellitus and HCB concentrations. Age was the only determinant that showed a consistent association with all compounds studied (positive); otherwise associations with single determinants varied among compounds even within the PCB group. This shows that the studied organochlorines should not be treated as a homogeneous group of compounds in epidemiologic studies.

Four behavioral experiments conducted in both the laboratory and the field provide evidence that adult sea lamprey (Petromyzon marinus) select spawning rivers based on the odor of larvae that they contain and that bile acids released by the larvae are part of this pheromonal odor. First, when tested in a recirculating maze, migratory adult lamprey spent more time in water scented with larvae. However, when fully mature, adults lost their responsiveness to larvae and preferred instead the odor of mature individuals. Second, when tested in a flowing stream, migratory adults swam upstream more actively when the water was scented with larvae. Third, when migratory adults were tested in a laboratory maze containing still water, they exhibited enhanced swimming activity in the presence of a 0.1 nM concentration of the two unique bile acids released by larvae and detected by adult lamprey. Fourth, when adults were exposed to this bile acid mixture within flowing waters, they actively swam into it. Taken together, these data suggest that adult lamprey use a bile acid based larval pheromone to help them locate spawning rivers and that responsiveness to this cue is influenced by current flow, maturity, and time of day. Although the precise identity and function of the larval pheromone remain to be fully elucidated, we believe that this cue will ultimately prove useful as an attractant in sea lamprey control.

No abstract

Background: We performed a cross-sectional study of associations between personal characteristics and lipid-adjusted serum concentrations of certain PCB congeners and chlorinated pesticides/metabolites among 323 pregnant primiparous women from Uppsala County (age 18-41 years) sampled 1996-1999.

No abstract

No abstract

In this study we tested the hypothesis that the presence of chemical stimuli from a hungry predator would initiate anti-predator responses, while stimuli from a satiated predator would not. We used chemical stimuli released from starved perch (Perca fluviatilis) and from satiated perch (predator). As prey we used adult Acilius sulcatus (Coleoptera: Dytiscidae). The reaction of the beetles to different predator conditions was tested during daytime. We also tested the reaction to starved perch during the night. A. sulcatus activity decreased when it was exposed to stimuli released from starved perch during daytime when visibility was poor, due to the presence of artificial vegetation. There was, however, no reaction to satiated perch under the same experimental conditions. These results indicate that A. sulcatus can discriminate between chemical cues from hungry and satiated fish predators. When visibility was good and the concentration of chemical cues was constant, the beetles did not react to starved perch in the daytime, but their activity decreased at night in response to stimuli released from starved perch. Visual as well as chemical cues seem to be important for detecting a potential predator. When visibility is good, beetles seem to rely on visual stimuli, while in darkness they seem to use chemical stimuli to detect the presence of predators.