Carbon dioxide sensitivity of pulmonary receptors in the frog.

Pulmonary mechano-receptors have been found in the frog lung that are sensitive to CO2 concentrations in the lungs and airways comparable to the physiological levels recorded in frogs. These results support the suggestion that a pulmonary receptor with distinct mechano- and chemosensitive properties may represent the functional precursor of the more specialized pulmonary receptor types which have evolved in birds and mammals.     

Crystal structure at 2.8 A resolution of a soluble form of the cell adhesion molecule CD2.

The crystal structure of a soluble form of the T lymphocyte antigen CD2 provides the first complete view of the extracellular region of a cell adhesion molecule. The topology of the molecule, which comprises two immunoglobulin-like domains, is the same as that of the first two domains of CD4 but the relative domain orientation is altered by a fairly flexible linker region. The putative ligand-binding beta-sheet forms a flat surface towards the top of the molecule. Crystal contacts between these surfaces suggest a plausible model for the adhesive interaction.     

The antifertility action ofa-chlorohydrin: Enzyme inhibition bya-chlorohydrin phosphate

Summary Preparations of the enzymes glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase are shown to be inhibited bya-chlorohydrin phosphate (II) in a competitive and non-competitive manner, respectively.a-Chlorohydrin (I), glycidol and epi-chlorohydrin have no inhibitory activities suggesting that their antifertility actions are due to their metabolism in vivo toa-chlorohydrin phosphate.     

Endogenous synthesis of lipid yolk in mosquito oocytes

Summary Morphological and physiological evidence indicate that lipid yolk in the mosquito is synthesized only within the oocyte within dense fields of free ribosomes. It does not come from the fat body or any other exogenous source.We are grateful to Dr A. L. Steinhauer for his support. Scientific article No. A2373, contribution No. 5388 of the Maryland Agricultural Experiment Station.     

Benzoyl cyanide in the defensive secretion of polydesmoid millipeds

Summary A novel cyanogenetic compound, benzoyl cyanide, was isolated from the defensive secretion of 3 polydesmoid millipeds (Pseudopolydesmus serratus, Apheloria corrugata and A. trimaculata). The secretion of the 3 species also contains mandelonitrile and benzaldehyde, and that of P. serratus contains mandelonitrile benzoate, benzoic acid, isovaleric acid, myristic acid and stearic acid.Paper No. 52 of the series Defense Mechanisms of Arthropods.The study was supported in part by the National Institutes of Health (grants AI-12020 and AI-02908 and Fellowship 1-F-32-CA05139 to T. H. J.) and the National Science Foundation (grant BMS 75-15084).