Glycoalkaloids of Solanum Series Megistacrolobum and related potato cultigens

Glycoalkaloids were used as evidence of the affinities of nine taxa of Solanum Series Megistacrolobum and related potato cultigens from western Bolivia. S. boliviense, S. sanctae-rosae and S. toralapanum contain the commertetraose sugar moiety and appear to represent a relatively wild group within the Series. S. megistacrolobum, S. sogarandinum and S. raphanifolium show anomolous glycoalkaloid profiles that probably reflect hybridization associated with human disturbance. Primitive forms of the S. χ ajanhuiri cultigen are indistinguishable chemicaliy from conspecific weeds that were previously classified as S. megistacrolobum. Variation in total glycoalkaloid content within Series Megistacrolobum likely reflects direct selection by humans for reduced glycoalkaloid levels during the domestication process.     

A strategy for high cell density culture of heterotrophic microalgae with inhibitory substrates

Substrate inhibition is one of the major problems preventing high cell densities of microalgae in heterotrophic culture, so the possibility of overcoming the problem by various culture techniques was examined. It was found that perfusion culture may be the most appropriate technique for high cell densities in heterotrophic culture using inhibitory substrates. An experimental example in which a hollow fibre cell recycle system (HFCRS) was employed to achieve high cell densities of Chlamydomonas reinhardtii on acetate under heterotrophic conditions of growth was demonstrated. The cell density in the HFCRS was much higher than that reported in the literature for this species.     

Fructose production by Zymomonas mobilis in fed-batch culture with minimal sorbitol formation

Summary Fed-batch cultures of Zymomonas mobilis (UQM 2864), a mutant unable to metabolise fructose, grown on diluted sugar cane syrup (200 g/l sucrose) achieved yields of 90.5 g/l fructose and 48.3 g/l ethanol with minimal sorbitol formation and complete utilization of the substrate. The effect of inoculum size on sorbitol formation in the batch stage of fed-batch fermentation are reported. Fermentation of sucrose (350 g/l) supplemented with nutrients yielded 142 g/l fructose and 76.5 g/l ethanol. Some fructose product loss at high fructose concentrations was observed. The fed-batch fermentation process offers a method for obtaining high concentrations of fructose and ethanol from sucrose materials.     

Potent and selective anti-HTLV-III/LAV activity of 2',3'-dideoxycytidinene, the 2',3'-unsaturated derivative of 2',3'-dideoxycytidine

2',3'-Dideoxycytidinene (ddeCyd), the 2',3'-unsaturated derivative of 2',3'-dideoxycytidine (ddCyd) is, like ddCyd itself, a potent and selective inhibitor of HTLV-III/LAV in vitro. This conclusion is based on the relatively high ratio of effective antiviral dose (0.3 microM) versus cell growth inhibitory concentration (20-35 microM) and the lack of any appreciable inhibitory activity against a series of non-oncogenic RNA and DNA viruses. Both compounds were considerably more inhibitory to human lymphoid cell lines than human nonlymphoid or murine cell lines. They were highly dependent on prior activation by deoxycytidine kinase to exert their anti-HTLV-III/LAV and cytostatic effects. In contrast with ddCyd, ddeCyd lost part of its anti-retrovirus effect upon prolonged incubation (10 days) with the virus-infected cells in culture.     

Effect of 100% O2 on passage of uncharged dextrans from blood to lung lymph

Since charge as well as size may influence the passage of plasma proteins from blood to lung lymph, we used uncharged dextrans as tracers to study the effects of hyperoxic lung injury on the molecular sieving properties of the pulmonary microcirculation in unanesthetized sheep. Polydisperse [3H]dextran was infused intravenously into five sheep before and after the animals breathed 100% O2 until lymph flow increased threefold (66-84 h). Lymph-to-plasma concentration ratios (L/P) were determined for [3H]dextran fractions of graded molecular sizes (1.6-8.4 nm effective radius) from samples obtained during the infusions. Before hyperoxia the blood-lymph barrier was highly restrictive to transport of [3H]dextrans above 5.0 nm in radius; steady-state L/P for these molecules averaged 0.03 or less. After the sheep breathed 100% O2, [3H]dextrans as large as 8.4 nm radius appeared in the lymph. Posthyperoxia, the L/P were significantly increased relative to prehyperoxia base-line values for every [3H]dextran fraction larger than 2.0 nm radius (P less than 0.05). In contrast, neither the L/P for albumin or total protein changed significantly. At autopsy, electron microscopy showed widespread damage to the endothelium of the alveolar capillaries with infrequent gaps between endothelial cells. In two control sheep, inhalation of compressed air for 96 h had no effect on lymph flow or L/P for the [3H]dextrans. We conclude that O2 poisoning reduced the selective sieving of uncharged dextrans across the blood-lymph barrier of the lungs and allowed larger dextrans to enter the lymph. These larger molecules may have leaked from the pulmonary microcirculation via disruptions in the continuity of the endothelial lining.     

A low copy number, copia-like transposon in maize.

Bs1, a transposable element that moved into the maize Adh1 gene following barley stripe mosaic virus infection, is shown to be present in 1-5 copies in all maize and teosinte lines tested. Bs1 sequences do not hybridize with the genome of barley stripe mosaic virus. The insertion of Bs1 is bounded by 304-bp perfect direct repeats, similar in structure to Ty1 in yeast, copia and related elements in Drosophila, and vertebrate pro-retroviruses, but different from all other known plant transposons. No free copies of the terminal sequences or large internal deletions of Bs elements could be detected. Bs1 is apparently not related to several transposons which moved into the Shrunken gene in lines made genetically unstable by barley stripe mosaic virus infection, suggesting that this virus may cause genome shock, resulting in a generalized liberation of transposons in response to environmental stress.     

THE LIPID COMPOSITION OF THORACOSPHAERA HEIMII: EVIDENCE FOR INCLUSION IN THE DINOPHYCEAE1

The fatty acid, sterol and chlorophyll composition of the calcified, unicellular alga Thoracosphaera heimii (Lohmann) Kamptner are reported. The presence of 4,23,24-termethyl-5α-cholest-22E-en-3β-ol (dinosterol), 4,23,24-trimethyl-5α-cholest-22E-en-3-one (dinosterone) and the predominance of C₁₈, C₂₀ and C₂₂ unsaturated fatty acids, including the acid 18:5ω3, indicates that T. heimii is a dinoflagellate. The fatty acid: sterol ratio (1.3), is typical of dinoflagellates. The geochemical significance of dinosterone, the high relative concentration of 4-desmethyl-5α-stanols and the role of 23-methyl-5α-cholest-22E-en-3β-ol in the biosynthesis of dinosterol in T. heimii are also discussed.