ALBERT

Notes: Summary Fruiting phenology and pattern of fruit removal of two shrubby dogwoods were examined in relation to fruit composition. It was predicted that fruit of the species bearing high fat fruit would disappear more rapidly and fall to the ground sooner than fruit of the species bearing low fat fruit. Field observation at two sites in central Pennsylvania contradicts these predictions. C. racemosa fruit, containing relatively high concentrations of crude fat, were retained on plants longer and fell into fruit traps later than c. amomum fruit, containing relatively low concentrations of crude fat. A substantial portion of the crops of both species fell under plants and most fallen fruit were secondarily removed. Potential explanations for patterns observed in this study are discussed.

Notes: Summary 1. Photoreceptors ofMusca were superfused with solutions containing either fluoride (F−), vanadate (VO 3 − ), or one of the GTP analogs GPPNHP and GTPγS. These agents have been reported to generate discrete voltage fluctuations (bumps) when injected intoLimulus photoreceptors. All four agents produced noisy depolarizations inMusca photoreceptors when added to the perfusate. 2. The effects of all four agents were reversible. GPPNHP induced dark noise only after exposure to light, whereas VO 3 − and F− did not require light for their effect. 3. Although individual bumps were too small to be resolved, the power spectra of voltage noise induced by these agents resembled closely those of light-induced noise. 4. F−-induced noise was reduced by adaptation following strong illumination. As F−-induced depolarization increased beyond 6 mV the voltage noise diminished, probably due in part to adaptation. With increasing F−-induced depolarization the power spectrum of F− noise changed shape slightly. Part of this change was probably due to adaptation, and it was similar to but smaller than corresponding changes in the spectrum of light-induced noise. 5. Analysis of F−-induced noise indicated that it was composed of bumps which, though similar in time course, were not identical to light-induced bumps. At small depolarizations, the F−-induced bumps were calculated to be 3–5 times smaller than light bumps and were less strongly affected by adaptation. Although the calculated duration of light-induced bumps diminished as intensity increased, the duration of F−-induced bumps showed no such dependence on depolarization, and was equal to that of light bumps in moderately dim light. Moreover light- and F-induced noise did not summate in the manner expected if they were indistinguishable to the photoreceptor. 6. In addition to noise, we saw other effects as well. The earliest effect of VO 3 − was a smooth depolarization which may have been due to this ion's role as a Na/K pump inhibitor. In experiments with some of these agents strong light caused a wave of afterdepolarization with no increase in noise. This effect occurred under a variety of conditions, however, and was not specific to the agents used. 7. F−, VO 3 − GPPNHP and GTPγS appear to generate noise inMusca photoreceptors through a common effect on the pathway of phototransduction. In the case of F− in particular, chemically induced bumps are smaller and less affected by adaptation than those produced by light. We discuss possible mechanisms of action consistent with these findings.

Notes: Abstract Dehydroergosterol has been widely used as a fluorescent analog of cholesterol for the investigation of lipoprotein, model membrane, and biological membrane structure. Although its synthesis was reported over fifty years ago, the complete structure and assignment of the three double bonds in the rings has not heretofore been firmly established. Therefore, dehydroergosterol was synthesized and purified by reverse phase high performance liquid chromatography. The proposed structure (Δ8, 7, 9(11), 22-ergostatetraen-3β-o1), including the location of the double bond at Δ9(11), was confirmed by mass spectroscopy,1H-NMR, and13C-NMR. In addition, a convenient assay for determination of impurities in dehydroergosterol preparations utilizing absorbance peak ratios is described. The spectroscopic properties of dehydroergosterol are highly dependent on solvent dielectric constant. Dehydroergosterol was incorporated into sonicated unilamellar vesicles composed of dimyristoylphosphatidylcholine or distearoylphosphatidylcholine. Arrhenius plots of dehydroergosterol fluorescence polarization indicated that the sterol was sensitive to the phase transitions of these phospholipids near 23° and 54°C, respectively. Differential polarized phase fluorescence and lifetime analysis were used to determine the dynamic properties of dehydroergosterol in the vesicles. At 37°C the limiting anisotropy, order parameter, and rotational rate of dehydroergosterol in dimyristoylphosphatidylcholine were 0.162, 0.65, and 0.71 nsec, respectively. The limiting anisotropy and order parameter, but not the rotational rate, of dehydroergosterol were sensitive to the temperature and/or the physical state of the phospholipid.

Notes: Abstract The removal of nitrilotriacetic acid (NTA) following acclimatization in an activated sludge pilot plant has been studied during transient changes in operating conditions. These changes included increases in hydraulic loading and influent chemical oxygen demand (COD) and such phenomena in combination with transient temperature reductions. Short-term increases in hydraulic loading from 1 to 2 dry weather flow (dwf) had a very limited effect on NTA removal. Increasing the influent COD had a slight effect on NTA removal. Short term increases in hydraulic loading combined with transient reductions in temperature significantly reduced NTA removal. The effect of these combined changes on NTA removal was synergistic, rather than additive. Increases in influent COD combined with transient temperature reductions also caused a significant reduction of NTA removal. The effect of such combined changes on NTA removal was at most only additive.

Notes: Abstract The removal of Cd, Cr, Cu, Pb, Ni, and Zn in an activated sludge pilot plant acclimatized to nitrilotriacetic acid (NTA) has been compared with an identically operated plant receiving no NTA. During steady-state operation the removal of Pb and Ni was reduced in the presence of NTA but there was no detectable difference in mixed liquor metal concentrations. Transient changes in the influent metal concentration of an order of magnitude had only a slight influence on NTA removal; Ni had the greatest effect, Cd and Cu some effect and Pb a negligible effect. Short term variations in influent NTA concentrations had no effect on NTA removal. A transient increase in influent NTA concentration caused a slight decrease in NTA removal. Transient increases in influent Ni concentration combined with reductions in temperature to 10 and 7.5 °C had a slight adverse effect on NTA removal. This effect did not appear to be additive or synergistic. Combinations of transient increases in influent NTA concentration and reductions in temperature caused a significant decrease in NTA removal. The effect was synergistic rather than additive.

Notes: Abstract Occultations and eclipses from ancient times down to the present are analysed to determine changes in the length of the day. By subtracting the expected tidal contribution from the observed changes, the non-tidal variations are obtained. The non-tidal varations are shown to occur on time-scales of decades and millennia.

Notes: Summary The left operator mutant λv2s develops poorly during infection as a result of constitutive expression of the left operon. A revertant of λv2s, designated λiri, was found to contain an inversion of the cI region with the inversion endpoints to be within the lambda operators o L and o R. Formation of the inversion is facilitated by a translocation of right operator o R c mutant sequence to the left operator in λv2s. The inversion in λiri positions wild-type o R sequence at o L returning control of the left operon to repression by the lambda cro repressor.