Temperature influences the handling efficiency of an aphid parasitoid through body size-mediated effects.

It is well known that increasing the ambient temperature increases the metabolic rate and consequently, the foraging rate of most insects. However, temperature experienced during the immature stages of insects affects their adult size (an inverse relationship). Because body size is generally correlated to foraging success, we hypothesized that temperature indirectly influences the foraging efficiency of adult insects through developmental effects. We first investigated the role of parasitoid: host body size ratio on the handling time of Aphidius colemani (Viereck) (Hymenoptera: Braconidae), then tested the prediction that increasing temperature during immature development increases the handling time of adults. As expected, parasitoids took longer to handle large aphids than small aphids. However, large parasitoids did not have shorter handling times than small parasitoids except when attacking large (adult) aphids. Developmental temperature had the predicted effect on parasitoids: Individuals reared at 25°C were smaller than those insects reared at 15°C. Parasitoids reared at 15°C had similar short handling times for both first instar and adult aphids, whereas parasitoids reared at 25°C took longer to handle adult aphids than first instar aphids. The size-mediated effect of temperature through development on parasitoid efficiency was opposite to the more familiar direct effect of temperature through metabolic rate. We conclude that the net effect of temperature on foraging insects will depend on its relative influence on immature and adult stages.

Physical mapping of the paralysis-inducing determinant of a wild mouse ecotropic neurotropic retrovirus.

We have recently shown that a molecularly cloned ecotropic retrovirus, initially isolated from the brain of a paralyzed wild mouse, retained the ability to induce hind limb paralysis when inoculated into susceptible mice (Jolicoeur et al., J. Virol. 45:1159-1163, 1983). To map the viral DNA sequences encoding the determinant of paralysis, we constructed chimeric viral DNA genomes in vitro between parental cloned infectious viral DNA genomes from this neurotropic murine leukemia virus (MuLV) and from nonneurotropic amphotropic 4070-A MuLV. Infectious chimeric MuLVs, recovered after microinjection of NIH 3T3 cells with these recombinant DNAs, were inoculated into newborn SIM.S and SWR/J mice to test the paralysis-inducing potential. We found that the 3.9-kilobase-pair SalI-ClaI fragment of the neurotropic MuLV comprising the 3' end of pol and all env sequences was sufficient to confer the paralysis-inducing potential to chimeric viruses. Therefore, this region of the neurotropic MuLV genome most likely harbors the primary determinant of paralysis.

Trace elements and acute phase reactants in gold treated rheumatoid arthritis patients.

Abnormal concentrations of trace elements, sulfhydryl groups, amino-acids and serum proteins were found in patients with rheumatoid arthritis similar to other chronic inflammatory conditions. These changes have been called the phase reaction. In this study, a systematic profile of the phase reactants was established in rheumatoid arthritis at the onset and during its modulation by chrysotherapy (gold sodium thiomalate 25 mg i.m. weekly). It was shown that this treatment, if successful, is capable of reverting to normal measures of the phase reaction. It was also found that the pattern of the profile varied in individuhe eventual beneficial or toxic effects. In these preliminary studies, no parameters or group of parameters of the phase reaction were predictive of the therapeutic outcome. Extended observations (over 6 months) and more individual profiles are being analyzed to gain insight into these features of inflammation and their modulation by chrysotherapy.

Trace element determination in serum by proton-induced x-ray emission.

We report the use of proton-induced x-ray emission (PIXE) as an analytical method in clinical research. The experimental set-up and target preparation procedures are briefly discussed together with the methods of automatic data acquisition and analysis. Results from a clinical project involving rheumatoid patients receiving chrysotherapy are presented.