Association of carbon disulfide with plants in the family Fabaceae.

We examined 40 taxa from nine genera within the subfamily Mimosoideae; 29 (73%) from six genera produced carbon disulfide (CS2). In addition, 19 of 40 taxa (48%) produced carbonyl sulfide (OCS). Of nine mimosoid taxa that produced CS2, all possessed a djenkolic acid and a cysteine lyase. Of three mimosoid taxa that did not produce CS2, two lacked a cysteine lyase and one lacked both a lyase and a djenkolic acid. Of 16 taxa from 14 genera from the other two subfamilies of the Fabaceae, the Caesalpinioideae and Papilionoideae, none produced CS2. The results suggest that CS2 production is common in the Mimosoideae and uncommon in the Caesalpinioideae and Papilionoideae and that plants in the Mimosoideae that do produce CS2 must possess both a djenkolic acid and a cysteine lyase for this production to occur.

Chemical composition of North American bee propolis and biological activity towards larvae of greater wax moth (Lepidoptera: Pyralidae).

Bee propolis is a sticky amalgamation of plant resins collected by honeybees (Apis mellifera L.) and used in the hive for filling cracks and repairing combs. Propolis contains a diversity of compounds of plant origin, and is reported to have medicinal, antimicrobial, insecticidal, and phytotoxic properties. We examined the physical and chemical composition of North American samples of bee propolis from several sites in North America and tested for bioactivity against larvae of the greater wax moth (Galleria mellonella L.), a common apiary pest. The amount of methanol-extractable resin in samples from Ohio and Georgia ranged from 24% to 79% by weight. Propolis collected from hives in Ohio was more chemically diverse (over 30 compounds detected by paper chromatography) than material from south Georgia (fewer than 10 major compounds) and contained a lower proportion of methanol-insoluble beeswax. The paper chromatographic surveys revealed little variation in the chemical profile of specific hives over a six-month period and no differences between propolis from adjacent hives. Four flavonoids were identified from propolis collected in Ohio: kaempferol, galangin, 3,3'-dimethoxyquercetin and 3-methoxykaempferol. When mixed into artificial diet, fractionated propolis reduced larval growth of the greater wax moth, but not dramatically. An array of phenolics reported from propolis (caffeic acid, chrysin, ferulic acid, galangin, kaempferol, and quercetin) were bioassayed individually for effects on larvae, but none reduced larval growth at the concentrations tested, suggesting that wax moths are tolerant of some phenolics in their diet.

Chloroplast DNA sequence from a miocene Magnolia species.

DNA has been successfully extracted from several samples of preserved tissue, the oldest so far reported originating from a 13,000-year-old ground sloth. Both severe damage to the preserved DNA, primarily due to oxidation of the pyrimidines, has prevented the acquisition of sequence data from ancient samples except in a few cases. We report here the extraction of DNA from fossil leaf samples from the Miocene Clarkia deposit (17-20 Myr old), the amplification of an 820-base pair (bp) DNA fragment from the chloroplast gene rbcL from a fossil of the genus Magnolia, and its subsequent sequencing. The sequence was verified by comparison with published and unpublished rbcL sequences. These results extend our ability to analyse ancient DNA and may open new avenues into problems in palaeobotany, biogeography, and in the calibration of mutation rates.

Geochemistry and thermolysis of flavonoids.

The thermal and pH stability of selected flavonoids has been determined under simulated geologic conditions. Thermolytic rates and products for various regimes, as determined by gas chromatography-mass spectroscopy, indicate the potential usefulness of flavonoids as thermometric indicators in sediments. The parametric factors affecting flavonoid stability are used to geochemically characterize angiosperm "green leaves" (36 to 25 x 10(6) years old) from Succor Creek and indicate that these sediments have not experienced temperatures higher than 80 degrees C or extreme pH shifts (beyond the range 6.3 to 7.2) during postdepositional maturation.

Flavonoids and other chemical constituents of fossil miocene zelkova (ulmaceae).

Organic solvent extractions of Zelkova oregoniana, a Miocene angiosperm compression fossil, indicate the chemical preservation of kaempferol, dihydrokaempferol, an n-alkane chain length range of 10 to 32 carbons, hydroxy acids, steranes, triterpenoids, and methyl pheophorbide a. This appears to be the oldest occurrence of flavonoids in fossil sediments reported.