Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone.

Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone hotspot. However, much of the helium emitted from this region is actually radiogenic helium-4 produced within the crust by α-decay of uranium and thorium. Here we show, by combining gas emission rates with chemistry and isotopic analyses, that crustal helium-4 emission rates from Yellowstone exceed (by orders of magnitude) any conceivable rate of generation within the crust. It seems that helium has accumulated for (at least) many hundreds of millions of years in Archaean (more than 2.5 billion years old) cratonic rocks beneath Yellowstone, only to be liberated over the past two million years by intense crustal metamorphism induced by the Yellowstone hotspot. Our results demonstrate the extremes in variability of crustal helium efflux on geologic timescales and imply crustal-scale open-system behaviour of helium in tectonically and magmatically active regions.

Annatto: a natural choice.

Annatto is a pigment derived from the seeds of Bixa orellana. It has been used from antiquity in South America and for over 100 years in Europe. It is now an important safe additive for a wide range of food, partly finding favour due to its natural origin.

Alkaloids of hairy root cultures of a Datura candida hybrid.

From the in vitro hairy root cultures of a Datura candida hybrid, 19 tropane alkaloids have been identified using capillary gas-liquid chromatography and mass spectrometry. As in the parent plants, scopolamine is the major alkaloid. Two hitherto undescribed alkaloids have been detected and their structure tentatively characterised on the basis of their mass spectral fragmentations.

High-yield production of tropane alkaloids by hairy-root cultures of aDatura candida hybrid.

Hairy root cultures were obtained following inoculation of the stems of sterile plantlets of aDatura candida hybrid withAgrobacterium rhizogenes. The scopolamine and hyoscyamine content was quantified by HPLC and compared with the non-transformed plants. The alkaloid yield (0.68% dry weight) obtained with the hairy roots was 1.6 and 2.6 times the amount found in the aerial parts and in the roots of the parent plants, respectively. Only a small proportion of alkaloids was released into the growth medium. Scopclamine was the principal alkaloid and the scopolamine/hyoscyamine ratio of ca. 5:1 makes these hairy roct cultures worthy of consideration as a source of scopolamine.

The 1986 lake nyos gas disaster in cameroon, west Africa.

The sudden, catastrophic release of gas from Lake Nyos on 21 August 1986 caused the deaths of at least 1700 people in the northwest area of Cameroon, West Africa. Chemical, isotopic, geologic, and medical evidence support the hypotheses that (i) the bulk of gas released was carbon dioxide that had been stored in the lake's hypolimnion, (ii) the victims exposed to the gas cloud died of carbon dioxide asphyxiation, (iii) the carbon dioxide was derived from magmatic sources, and (iv) there was no significant, direct volcanic activity involved. The limnological nature of the gas release suggests that hazardous lakes may be identified and monitored and that the danger of future incidents can be reduced.

Tropane alkaloids of species of anthocercis, cyphanthera and crenidium.

Eight tropane alkaloids, anabasine and ursolic acid have been isolated from the newly-described species CRENIDIUM SPINESCENS. ANTHOCERCIS ILICIFOLIA possesses a similar alkaloid spectrum to that of A. LITTOREA to which it is taxonomically closely related. In alkaloid composition, A. GENISTOIDES is a variable species and the sample analysed here contained meteloidine as principal alkaloid. The alkaloids of CYPHANTHERA ODGERSII and C. TASMANICA are consistent with those of other species of the genus. At present, ursolic acid does not appear to be a useful characteristic for the classification of solanaceous taxa belonging to Anthocercideae.

Chemical and toxicological studies on bracken fern, Pteridium aquilinum var. latiusculum. VIII. The inability of bracken extracts containing pterosins to cause cattle bracken poisoning.

Methanol extracts of bracken frond and rhizomes prepared using a metallic extraction vessel, were proved incapable of producing bracken poisoning in calves. Nevertheless, they contained appreciable quantities of pterosins and pterosides. Thus the poisonous principle(s) in bracken responsible for the toxicological effects are not associated with these major sesquiterpenoids of the plant.

The comparative phytochemistry of the genus Erythroxylon.

Recent research suggests that, in addition to the well-documented occurrence of significant quantities of cocaine and related alkaloids in a limited number of species, the genus Erythroxylon will prove to be a rich source of tropane alkaloids. These bases are esters of a range of acids with tropine, 3 alpha, 6 beta-dihydroxytropane and 3 alpha, 6 beta, 7 beta-trihydroxytropane; the numbers are further increased by nor-derivatives, and stereoisomerism involving the C-3 hydroxyl of the tropane skeleton. The diterpenes of the genus also appear worthy of further study.

A steroid constituent from Solanum abutiloides.

A steroidal aglycone, isonuatigenin, has been isolated from the hydrolysate of unripe fruits of Solanum abutiloides. The acetylation of isonuatigenin in weak acid has been studied.

Biochemistry of the bacterial catabolism of aromatic compounds in anaerobic environments.

Methods of aerobic degradation of aromatic compounds in the biosphere are well understood, but it is only relatively recently that it has been shown how some bacteria can also degrade these substrates in the absence of molecular oxygen. This occurs by photometabolism (Athiorhodaceae), nitrate respiration (Pseudomonas and Moraxella sp.) and methanogenic fermentation (a consortium) in which the benzene nucleus is first reduced and then cleaved by hydrolysis to yield aliphatic acids for cell growth. These methods may be used by microbial communities to catabolise man-made pollutants.