Saprophytic production of Clavine alkaloids and activity of Hydroxymethylglutaryl-CoA reductase

In submerged Claviceps cultures the activity of hydroxymethylglutaryl-CoA reductase preceded the increase of alkaloid production and of sterol content. During the first alkaloid phase, cell mevalonate was involved in the biosynthesis of both alkaloids and steroids. In the second production phase, it was predominantly used for alkaloid synthesis. Hydroxymethylglutaryl-CoA reductase appears to be a suitable target for physiological manipulation to increase clavine alkaloid yields.     

The decolorization of the polymeric dye Poly-Blue (polyvinalamine sulfonate-anthroquinone) by lignin degrading fungi

Summary In this work we have investigated the decolorization of the polymeric dye Poly-B411 by several fungi. Only fungi with known lignin degrading ability were able to decolorize the dye. Pleurotus ostreatus sp. florida decolorized the dye both in solid and liquid media. Decolorizing ability developed in the absence of the dye but only when the fungus had been previously cultivated on lignin containing substrates.The work was supported by a grant from the Charles Wolfson Trust     

Protoplast forming ability in the genusBrevibacterium

Formation of protoplasts and their reversion were followed in 7 strains of brevibacteria. The formation of protoplasts and their reversion differed both between various species of brevibacteria and between various mutant strains of the same species.     

Relationships between macroalgal functional form groups and substrata stability in a subtropical rocky-intertidal system

The general hypothesis that morphological, physiological, and ecological adaptations of macro algal functional-form groups can be related to the level of disturbance encountered in a natural environment was examined. Two articulated calcareous coralline algae (Amphiroa van-bosseae Lemoine, 24% cover and Corallina frondescens Post. & Rupr. 20%) and one non-articulated coralline alga (Lithophyllum sp., 16%), all late-successional predation-tolerant strategists, comprise most of the community cover on stable bedrock substrata at Punta Las Cuevitas, Sonora, Mexico. Conversely, Ulva rigida C. ag. (26% cover) and a ralfsioid crust (23%), shows to be early-successional opportunistic strategists, cover more of the disturbed boulder habitat. Porolithon sonorense Daws., a stress-tolerant strategist, is uniquely abundant on both substratum types (13% cover on boulders, 10% on bedrock). The sheet-like and filamentous algae, prevalent in the temporally unstable habitat, generally show greater productivity (>2×) than the thicker and calcareous forms conspicuous in the more constant environment. It appears that selection for delicate thalli with high productivities, as well as selection for tougher morphologies having lower photosynthetic rates due to greater proportions of structural tissues, are widespread, divergent evolutionary forces among marine algae. Experiments with captive sea urchins (Echinometra vanbrunti Agassiz), in conjunction with fish-preference data published for some of the same algae studied here, offer strong support for the functional-form model. Parrotfishes, rudderfishes, surgeonfishes, damselfishes and E. vanbrunti, in the Gulf of California, preferentially feed on delicate, early-successional, sheet-like, and filamentous algae, while rejecting or ignoring the more structured, late-successional and calcareous algae. There is no significant (P > 0.05) gradation in calorific content between the first four of the six functional groups (i.e., Sheet-, Filamentous-, Coarsely Branched- and Thick Leathery-Groups), but the mean value for these fleshy forms (2.6 kcal · g ash-free dry wt^?1) is significantly greater than that for the last two groups (0.3 kcal, Jointed Calcareous- and Crustose-Groups). The approach used in this study demonstrates a realistic technique for predicting macrophyte community composition from knowledge of the disturbance levels in a given habitat or the reverse. The form group-disturbance relationship has important implications for future biological monitoring of rocky-inter-tidal and subtidal systems.     

Directional control and the functional organization of defensive responses inAplysia

Noxious cutaneous stimulation of anterior sites on Aplysia californica causes withdrawal and turning followed by escape locomotion. Stimulation of anterior sites causes significantly larger turning responses than does stimulation of posterior sites, so that escape locomotion is always directed away from a site of 'attack'. Later phases of escape locomotion are often the same, regardless of the site of the triggering stimulus. The defensive secretions, ink and opaline, are directed along the anterior-posterior axis at the source of noxious stimulation. Ink and opaline ejections are directed to the front or back of the animal by characteristic responses of the siphon, mantle, and parapodia. Ink and opaline are ejected by a series of coordinated pumping movements of the mantle, gill, and parapodia that closely resemble triggered 'respiratory pumping' or 'Interneuron II' episodes (Kupfermann and Kandel 1969; Byrne and Koester 1978; Hening 1982). The directed ejection of secretions from the mantle cavity in response to noxious stimulation suggests a number of potential defensive functions for these secretions including aggressive retaliation, startle display, diversion, and alarm signalling (Edmunds 1975). Taken together, our results and others' suggest an integrated scheme for the functional organization of overt defensive behavior in Aplysia, and begin to suggest testable hypotheses about the integration of defensive responses on the cellular level in this animal.     

Surface-charge related actions of polylysine on thylakoid membranes

Polycation binding to the negatively charged surface of chloroplast thylakoid membranes is known to cause an inhibition of photosystem I activity. It also interferes with the cation-dependent rearrangement of chlorophyll proteins in the thylakoid membrane. It was shown that added anions prevented or reversed the inhibition of photosystem I by polylysine without decreasing its binding to the membranes. Anions also caused a change in the interaction of the chlorophyll proteins in polylysine-treated thylakoids as indicated by an increase in the relative fluorescence intensity from photosystem II. In both cases, the relative effectiveness of the anions tested depended on their valence; for example, the tetravalent species Fe(CN)₆^4t- was effective at a concentration at least 2 orders of magnitude lower than the divalent species SO₄^2?. These results suggest that anions act by screening the positive charge of the polylysine-coated membrane surface. Measurements of the response of the anionic fluorescent probe 1-anilinonapthalene-8-sulfonate to an addition of anions to polylysine-treated thylakoids supported this contention. It was concluded that the action of polylysine on photosystem I and on the chlorophyll proteins is mediated by changes of the electrical properties of the thylakoid membrane and may not involve a direct binding of the polycation to the affected membrane proteins.     

Paleolimnology of the Peten Lake District,Guatemala

Long-term changes of sedimentary particle-size distribution in two tropical lowland lakes were compared with changes of human population sizes, estimated archaeologically, in the drainage basins. Mean particle size of silt and clay fractions (<64 µm) varied between 3 and 15 µm. High positive skewness and kurtosis of the distributions were associated with smaller particle sizes; hence small mean size resulted from greater influx of small particles while influx of larger particles was probably constant. An inverse correlation between mean particle size and human population size is interpreted to mean that disturbance-induced erosion results in delivery of very fine inorganic particles at higher rates. Within any one basin, particle-size stratigraphy is more precisely related to archaeological time periods than is pollen stratigraphy. An absolute chronology still eludes us, owing to the failure of ¹⁴C dating of calcareous, colluvial sediments, but our relative chronology is now more precise than before. If certain assumptions about past hydrologic relations can be met, particle-size analysis is a way of comparing the histories of geographically very different lakes, including lakes from tropical, temperate, and arctic regions.