Stereoselectivity in mammalian chemical communication: Male mouse pheromones

Two male mouse pheromones, 3,4-dehydro-exo-brevicomin (DHB) and 2-sec-butyldihydrothiazole (SBT), are chiral molecules which were previously tested in their respective bioasays as racemic mixtures. The focus of this study has been to determine the absolute configuration of their natural forms and its relation to stereospecific biological action. DHB was established as the R,R-enantiomer possessing biological activity. Due to an extremely easy racemization of SBT under very mild conditions, enantioselectivity of its transmission and its action at the receptor site appear to be of secondary importance.     

Effect of different bathing media on the short-circuit current across the intestine of the rat and guinea-pig

Summary The changes in short-circuit current occurring when one or both solutions bathing the intestine of rat or guinea-pig mounted in flux chambers were recorded. The results with the guinea-pig can be explained in terms of diffusion potentials arising from the ionic replacements, and an electrogenic sodium pump, sensitive to ouabain, in the contraluminal membrane of the cell. In the rat, the situation is more complicated, and the enterocyte probably possesses an electrogenic sodium pump in the brush-border membrane.     

Effect of gum Arabic on aminopyrine demethylation in rats

Summary Stimulation of aminopyrine demethylation induced in rats by oral or i.p. administration of phenobarbital was partially inhibited in animals receiving daily treatments of 2×200 mg/kg gum Arabic p.o.     

Frequency-domain study of the mechanical response of living striated muscle

Summary Small-amplitude sinusoidal displacements, in the frequency rang 4–100 Hz, were applied to intact whole frog sartorius muscle whilst in a state of tetanus. At low frequencies the muscle, was observed to do oscillatory work, while at higher frequencies it tended towards elastic behaviour. Frequency-response plots obtained were compared with those from other muscle preparations. Results were interpreted in terms of mechano-chemical transduction properties of muscle.The authors wish to thank the Australian Research Grants Commission for provision of the laser, and L. I. Patterson for construction of the mechanical apparatus.     

Estrogen receptor in uteri of mice of different H-2 genotypes.

A relationship between the amount of available estradiol receptors in uteri of inbred mice and their H-2 genotype is suggested by study in congenic animals.     

Solubility of the neurosecretory products of Crepidula fornicata Phil., a prosobranch mullusk]

Study of solubility of neurosecretory products in Crepidula fornicata shows that the presence of ethanol in the fixative is incompatible with good fixation. This character permits the choice of a more effective extraction technique. An experimental study in organ culture shows that the action of differentiation of brain appears in the extract obtained by this method.