Interactions ofΔ 11-tetrahydrocannabinol with cannabinol and cannabidiol following oral administration in man. Assay of cannabinol and cannabidiol by mass fragmentographywith cannabinol and cannabidiol following oral administration in man. Assay of cannabinol and cannabidiol by mass fragmentography

Summary Oral administration to man of 20 mg ¹1-tetrahydrocannabinol (THC) together with placebo or 40 mg cannabinol (CBN) or 40 mg cannabidiol (CBD) gave evidence of a possible limited interaction of THC with CBN but not with CBD as indicated by average plasma THC levels. Peak CBD and CBN concentrations were similar to that of THC, viz. about 5–8 ng/ml.Supported by the Swedish Medical Research Council and grant MH-00424 from the Veterans Administration.     

The effect of ion pair formation on the antimuscarinic activity of methantheline.

The quaternary ammonium compound, methantheline, was found to antagonize acetylcholine induced contractions in isolated guinea pig ileum by a mechanism which did not conform to the criteria for either competitive or non-competitive inhibition. Enhancement of the lipid solubility of methantheline by formation of an ion pair with trichloracetate failed to influence its cholinergic inhibitory activity. The results suggest that in the guinea pig ileum a) an intracellular site of action does not exist for methantheline and b) the membrane receptors for methantheline most likely are located in an aqueous environment.     

The lateral transport of indoleacetic acid-C14 in geotropism

Zusammenfassung Die Hypothese, dass eine geotropische Reizung von Hafer-Koleoptilen eine Querverschiebung des Wuchsstoffes zur Folge hat, ist mit radioaktiver-Indolylessigsäure (Indol-CH₂C¹⁴OOH) bestätigt worden. Das Verhältnis der aus der oberen und der unteren Flanke von Koleoptil-Zylindern mit Agarblöckchen abgefangenen Indolylessigsäure wurde gleich 40:60 gefunden.Die Ursache dafür, dass dieser Effekt in längshalbierten Koleoptilen nicht festgestellt worden ist, liegt im grossen Anteil nicht transportierten Auxins in den Koleoptilen.

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This work was supported by a National Science Foundation predoctoral fellowship toBarbara Gillespie and by a grant from the National Science Foundation, No. G-9084, to ProfessorK. V. Thimann.     

Dynamics of rodent populations in semiarid habitats in Lassen County, California

From 1996 to 2004, we studied population dynamics of a rodent assemblage in semiarid habitats in Lassen County, California. Abundances of rodents appeared affected by fluctuations in precipitation from a high in 1996 to average and slightly below-average levels in subsequent years; perhaps reflecting this, assemblage composition also changed dramatically during the study period. California kangaroo rats ( Dipodomys californicus ) declined from abundant to extremely rare, abundances of deer mice ( Peromyscus maniculatus ) fluctuated greatly during the study period, and, perhaps most notably, populations of dusky-footed woodrats ( Neotoma fuscipes ) appeared to decline to local extinction, possibly allowing for the subsequent colonization of desert woodrats ( N. lepida ). These changes appeared to represent natural variation in numbers and composition in an ecologically dynamic ecotonal region in response to multiyear changes in precipitation.     

Molecular basis of mechanosensory transduction

Mechanotransduction - a cell's conversion of a mechanical stimulus into an electrical signal - reveals vital features of an organism's environment. From hair cells and skin mechanoreceptors in vertebrates, to bristle receptors in flies and touch receptors in worms, mechanically sensitive cells are essential in the life of an organism. The scarcity of these cells and the uniqueness of their transduction mechanisms have conspired to slow molecular characterization of the ensembles that carry out mechanotransduction. But recent progress in both invertebrates and vertebrates is beginning to reveal the identities of proteins essential for transduction.     

Planetary science: are there active glaciers on Mars?

Head et al. interpret spectacular images from the Mars Express high-resolution stereo camera as evidence of geologically recent rock glaciers in Tharsis and of a piedmont ('hourglass') glacier at the base of a 3-km-high massif east of Hellas. They attribute growth of the low-latitude glaciers to snowfall during periods of increased spin-axis obliquity. The age of the hourglass glacier, considered to be inactive and slowly shrinking beneath a debris cover in the absence of modern snowfall, is estimated to be more than 40 Myr. Although we agree that the maximum glacier extent was climatically controlled, we find evidence in the images to support local augmentation of accumulation from snowfall through a mechanism that does not require climate change on Mars.