An ecological study of Phaenocora unipunctata (Örsted) (Turbellaria; Rhabdocoela): predator-prey interrelationships

The diet of P. unipunctata living in an English pond was investigated by examination of the gut contents of field-collected specimens, by a serological method and by laboratory experiments. Tubificids, and to a lesser extent lumbriculids, are the preferred food of small and large flatworms. In the laboratory damaged Cladocera and Chironomidae were fed upon to a very limited extent and in the serological tests a few flatworms gave a positive reaction with anti-Cladocera and anti-Chironomidae sera, but it is unlikely that these taxa are preyed upon extensively in the field. Communal feeding occurs. Algae and Protozoa are not eaten. P. unipunctata has no competitors for the oligochaete resource in the pond.Predators of the flatworm were determined mainly by laboratory experiments. Only the larvae and adults of Dytiscus attacked a few specimens. It is unlikely that flatworm and its cocoons have any serious predators in the pond.     

Uptake of amino acids in reconstituted vesicles derived from plasma membranes of Ehrlich ascites cells.

To obtain a clearer concept of the mechanism of organic solute transport in mammalian cells, we have attempted to reconstitute a functional transport system for amino acids from plasma membranes of Ehrlich ascites cells. Purified plasma membranes were dissolved in 2% Na cholate--4 M urea, a mixture which brought over 85% of the membrane proteins into solution. After centrifugation of the solubilized material for 2 hrs at 100,000 x g, the supernatant was dialyzed in the cold for 20 hrs with additional lipid. The reformed vesicles were tested for the ability to transport amino acids. The preliminary results obtained show that the uptake of alpha-aminoisobutyric acid can be inhibited by L-methionine and much less by L-leucine as would be predicted from the known properties of alpha-aminoisobutyric transport in the intact cells. In addition, it has been possible to show accelerated efflux of intravesicular phenylalanine when phenylalanine is added to the trans side (medium side). The data are consistent with the conclusion that there is carrier mediated transport in the reconstituted vesicles.     

Pharmacology and Diagnosis of Pesticide-Induced Illnesses

Although emphasis upon the concept of environmental health is a recent development in the medical community at large, the environment in which man worked has been of considerable concern to physicians in occupational medicine for a quarter of a century or more.Among the environmental factors which may adversely affect the health of exposed persons are the pesticides. The pharmacologic properties of these chemicals as well as the diagnostic signs and symptoms are presented herein.