ALBERT

Notes: . The dynamics of cytoplasmic streaming, retrograde translocation of externally bound particles and locomotion by Entamoeba invadens were compared. Locomoting amoebae were monopodial, exhibited fountain flow cytoplasmic streaming and translocated externally bound erythrocytes to the rear of cells. The rates of rearward flow of peripheral cytoplasmic vacuoles and of the externally bound particles were equal to the rate of cell forward locomotion. Rhodamine-phalloidin staining revealed a distinct cortical polymerized actin cytoskeleton. This was least evident about the periphery of the advancing pseudopod, increased in density toward the rear of the cell and was most concentrated in the uroid. A monoclonal anti-eucaryotic actin antibody, which recognized monomeric Entamoeba actin on immunoblots, stained trophozoites by indirect immunofluorescence throughout the cytoplasm, but not in the cortical regions stained by rhodamine-phalloidin. This and other evidence implied that the antibody recognized only unpolymerized actin in Entamoeba. We propose that locomotion, cytoplasmic streaming and translocation of externally bound particles are driven by a common actin-based mechanism in Entamoeba, possibly involving retrograde cortical actin flow and recycling.

Notes: The power auger is a useful tool in the fields of ground-water geology and hydrology. The Ohio Division of Water has had excellent success in utilizing this type of equipment during the past seven years. Augering is an economical and effective method of drilling test holes in unconsolidated deposits provided the tool is used within its limitations and where it works best. The augering method is particularly useful to the ground-water investigator exploring sand and gravel aquifers or buried bedrock valleys, installing drive points, and making seismic refraction surveys.

Notes: Volatile compounds in the aroma of five varieties of roasted and unroasted (raw) cocoa beans have been identified by mass spectral analysis and gas chromatography. The five common varieties selected for this study all contain the following compounds usually in this order of abundance: isovaleraldehyde, isobutyraldehyde, propionaldehyde, methyl alcohol, acetaldehyde, methyl acetate, n-butyraldehyde, and diacetyl. An additional eight compounds appear in smaller amounts. As evidenced by gas chromatographic analysis, the raw bean aroma contains the same components but in lower concentrations. The principal differences between varieties are shown to be due to the ratios of these compounds rather than new compounds. The effect of roasting period on the concentration of four aldehydes in the aroma of the ground bean is shown.

Notes: SUMMARY. 1. The pattern of fluctuations in the total biomass and species composition of phytoplankton in the shallow, eutrophic Loch Leven exhibits considerable inter-annual and within-year variability. Nevertheless, studies over the 18-year period reviewed here (1968–85) show that many of the observed changes can be explained in -terms of light regimes and the concentrations and fluxes of nutrients. On occasion, the incidence of fungal parasitism and of protozoan, rotiferan and crustacean grazing is also important.2. Changes in annual mean algal biomass from very high levels in the late 1960s and early 1970s to somewhat lower levels in the late 1970s, followed by occasional high peaks in the present decade, are attributed to shifts in phosphorus loading-particularly from a P-rich industrial source.3. In spite of complex and erratic sequences of algal species, seasonal patterns in the size distribution of the phytoplankton assemblage have been identified. However, these also changed. During the 4 years prior to 1971, Daphnia hyalina was not recorded in the plankton, and small algae have been abundant only in late winter or early spring.4. The potential importance of the weather is highlighted as one of the possible causes of the irregular appearance of algal species. The effect of the characteristically variable, oceanicclimate of Northern Britain on this large (13.3 km2), shallow (z̄= 3.9 m) loch is thought to be of particular importance.5. The influence of the weather on phytoplankton sequences is explored by comparing records of monthly flushing rate values with time-series data on aspects of the aquatic environment and plankton populations. The preliminary assessment suggests that variation in flushing rate (p) has a considerable effect on temperature regimes and the supplies and in-loch dynamics of nutrients; through such changes, p controls major features of phytoplankton succession such as the temporal abundance of diatoms, as well as detailed sequences of events relating to the development and collapse of particular algal species - and. as a consequence, in some cases, of the animals preying on them.6. Concluding remarks emphasize how little would have been understood about the functioning of shallow lakes, had the long-term commitment to Loch Leven research been abandoned. The view is also expressed that the findings are of considerably greater relevance to research on ‘classic’ stratifying lake systems, than the focus on the shallow waterbody might hitherto have suggested.

Notes: 1. Levels of ash-free dry matter (AFDM) and chlorophyll a in epilithon, benthic participate organic matter (BPOM), invertebrate assemblage composition, and biomass of functional feeding groups were compared in winter and summer at forest and pasture sites in three Victorian streams.2. Chlorophyll a concentrations of epilithon were significantly higher at pasture than forest sites in winter but not in summer while BPOM was not significantly greater at forest sites in either season. Epilithic biomass as AFDM did not show consistent differences between land uses or seasons.3. Total biomass of invertebrates did not differ between forest and pasture sites but the biomass of shredders was significantly higher, and that of grazers significantly lower, at forest than pasture sites. A site shaded with an artificial canopy behaved as a forest site for grazers but as a pasture site for shredders.4. Cluster analyses of invertebrate assemblages grouped pasture sites with forest sites on the same stream at the same season, indicating that assemblage composition was less influenced by land-use differences than by between-stream and seasonal differences.5. Biomass of functional feeding groups appeared to be a more sensitive indicator of invertebrate assemblage response to land-use alteration than either species diversity/ richness measures, or multivariate assemblage composition measures.