Light-driven movements of the trifoliate leaves of bean (Phaseolus vulgaris L.). Activity of blue light and red light

The puhrinule of the terminal leaflet in the trifoliate leafof bean (Phaseolus vulgaris L.) responds to its continuous exposureto directional overhead light by increasing the elevation ofits attached lamina. Blue light drives this response, but theeffectiveness of unfiltered white light equalled, or exceededthe effectiveness of blue light at equivalent irradiances (200–800µmol m^–2 s^–1). Adding red light to blue lightenhanced the initial rate of response, and increased its steady-state.These effects of red light increased with irradiance. Adding200–800 µmol m^–2 s^–1 red light to 50µmol m^–2 s^–1 blue light was more effectivein enhancing the initial rate of response than adding blue lightat equivalent irradiances, whereas added blue light was moreeffective in increasing the steady-state. In continuous bluelight the initial (maximal) angular velocity of laminar reorientation,as well as the eventual steady-state of the response increasedlinearly with log PFD (up to 800 µmol m^–2s^–2).Laminar reorientation also took place in continuous red lightby itself, and the angular velocity of the response was initiallyhigh, then became considerably slower. The initial phase wasapparently independent of irradiance up to PFD 100 µmolm^–2 s^–1 but increased progressively with log PFDat higher irradiances. During the second phase, the rate increasedlinearly with irradiance, becoming saturated at PFD 200 µmolm^–2 s^–1. Key words: Phaseolus, phototropism, pulvinule, spectral dependence, trifoliate leaf movements     

Further Effects of Light Intensity, Carbon Dioxide Concentration, and Day Temperature on the Growth of Chrysanthemum morifolium cv. Bright Golden Anne in Controlled Environments

In earlier work the effects of light intensity over the range31 to 250 J cm^–2 day^–1 and carbon dioxide concentrationfrom 325 to 900 ppm with 8-h days at 18.3 °C and 16-h nightsat 15.6 °C were described. The present paper is concernedwith three further experiments with light levels up to 375 Jcm^–2 day^–1 (which corresponds to the daily totalin a glasshouse in southern England in early May or August andthe intensity is approximately that of mid-winter sunshine),carbon dioxide concentration up to 1500 ppm, and day temperaturesof 18.3 to 29.4 °C. Final plant weight was increased by light over the range 125–375J cm^–2 day^–1 and by carbon dioxide over the range325–900 ppm, with positive interaction between them; thisinteraction was increased by raising the temperature to 23.9°C and somewhat more at 29.4 °C day temperature. Leaf-arearatio and specific leaf area were reduced by increasing eitherlight or carbon dioxide but there was little effect of temperature.Leaf-weight ratios were uniform within experiments but therewere small consistent differences between one experiment andthe other two which also affected leaf-area ratios. Mean unit leaf rate was scarcely affected by day temperatureover the range investigated. There were the usual increasesdue to increased light and carbon dioxide concentration anda consistent difference in absolute value between one experimentand the other two. These differences in mean unit leaf rateare illustrated in detail in the ontogenetic trend of unit leafrate and plant size. Lower unit leaf rates were to a considerableextent compensated for by increased leaf-area ratios in theusual way. Despite the substantial differences in day temperature the specificwater contents (g water g dry weight^–1) differed little,showing in the majority of cases higher values in the highertemperature for otherwise similar treatment combinations. Flower development was somewhat delayed at 23.9 °C day temperature,and substantially so at 29.4 °C. Lateral branch length wasincreased at 23.9 °C and excessively so at 29.4 °C.This reveals quite clearly that a temperature optimum for vegetativegrowth may not be the optimum for flowering performance norproduce a desirable plant shape. Despite the marked effects of temperature on rate of flowerdevelopment, the relationship between flower development andthe ratio of flower to total weight was the same for all treatmentcombinations in all three experiments and coincident with thatreported earlier. Gasometric determinations indicated that respiratory loss bythe whole plant was a smaller proportion of net photosyntheticgain at a temperature of 29.4 °C than at 18.3 °C andwas likewise a smaller proportion at 1500 ppm carbon dioxidethan at 325 ppm. If photorespiration of leaves is assumed tobe as great as their dark respiration, the respiratory lossesare in the range of 31–50 per cent of the gross gain.Greater rates of photorespiration would increase the proportionaterespiratory loss.     

Bulb Development in Onion (Allium cepa L.) II. The Influence of Red: Far-red Spectral Ratio and of Photon Flux Density

Bulb development was followed in four onion cultivars growingin controlled environments under 17 h days in factorial combinationsof photon-flux densities (PFD) of 111 and 333 µmol m^–2s^–1 with red: far-red spectral ratios (R : FR) of 2.88and 1.41. A PFD of 111with R : FR of 0.86 was used in a secondexperiment. The lower the R : FR or the higher the PFD the higherthe mean bulbing ratio and the ratio of bulb plus sheath toleaf blade dry weight and the earlier the bulb swelling. LowerR : FR accelerated scale initiation as did the higher PFD underR : FR 2.88 but not under R : FR 1.41. In high PFD bulb swellingoccurred before scale initiation because many sheaths of bladedleaves thickened, but in low PFD and low R : FR bulb swellingand scale initiation were concurrent. In the low PFD a low R: FR increased soluble carbohydrate concentrations in sheathsand scales compared to high R : FR. In high PFD, soluble carbohydrateconcentrations did not vary with R : FR and were higher thanunder low PFD. Onion, Allium cepa L., bulb, photon flux density, red: far-red ratio, light spectral quality, soluble carbohydrate     

Alterations in Neurobehavioral Responses in Fishes Exposed to Lead and Lead-chelating Agents

Lead (Pb) is a neurotoxic element that causes behavioral dysfunctionin fishes within days of exposure to sublethal concentrations.To test the hypothesis that internal stores of Pb have long-termbehavioral effects, Pb-exposed (0.3 ppm) fish were either treatedwith the Pb-chelating drug meso-2,3 dimercaptosuccinic acid(DMSA) or returned to controlconditions (0.0 ppm Pb). Swimmingcapacity improved after a 7-day DMSA (1.5 ppm) exposure (ANOVAP < 0.05). Removing fish from conditions of waterborne Pbdid not achieve this result; DMSA alone without Pb pretreatmenthad no significant effect. Blood Pb (BPb) levels in controlor DMSA-only fish were not detectable. Treated groups had significantlyhigher BPb (ANOVA, P < 0.05): Pb-exposed fish—530.5± 156.7, 884.6 ± 130.0 ppm (1, 2 wks, respectively);Pb-exposed 0.0 ppm water—488.8 ± 67.3 ppm after2 wks; Pb-exposed 1.5 ppm DMSA—202.0 ± 116.0 ppmafter 2 wks. Norepinephrine and vanillylmandelic acid levelswere altered by Pb exposure (ANOVA, P < 0.05). Whereas removingPb did not facilitate a return to control values, adding DMSAdid (ANOVA, P < 0.05). Temporal-spatial response patternsto a stimulus in Pb-exposed (0.1 ppm) and Pb-exposed 0.0 ppmPb water groups differed from controls (0.0 ppm Pb; 0.0 ppmDMSA) for stimulus response angle, and rate and extent of movementaway from stimulus source. While the two control types weresimilar for stimulus response angle and reaction time, DMSA-onlycontrols, unlike 0.0 ppm Pb controls, did not respond as a tightly-associatedgroup after the stimulus.     

Metabolism of Explosive Compounds by Sulfate-Reducing Bacteria

The metabolism of various explosive compounds—1,3,5-trinitrobenzene (TNB), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine (HMX)—by a sulfate-reducing bacterial consortium, Desulfovibrio spp., was studied. The results indicated that the Desulfovibrio spp. used all of the explosive compounds studied as their sole source of nitrogen for growth. The concentrations of TNB, RDX, and HMX in the culture media dropped to below the detection limit (<0.5 ppm) within 18 days of incubation. We also observed the production of ammonia from the nitro groups of the explosive compounds in the culture media. This ammonia served as a nitrogen source for the bacterial growth, and the concentration of ammonia later dropped to <0.5 mg/L. The sulfate-reducing bacteria may be useful in the anaerobic treatment of explosives-contaminated soil. Received: 23 January 1998 / Accepted: 5 March 1998     

Photoinhibition and Its Recovery in Two Strains of the Cyanobacterium Spirulina platensis

Two strains of Spirulina platensis, marked Sp-G and Sp-RB, werestudied for their response to high photon flux densities (PFD).Sp-RB, a gas vacuolated strain, appeared more sensitive to thehigh PFD treatment as compared with Sp-G, a non-vacuolated strain.The loss of the photosynthetic activity due to the photoinhibitorytreatment was obtained at the level of whole cells as well asthe membrane level. Sp-RB was more sensitive than Sp-G at bothlevels. Experiments using chloramphenicol during the photoinhibitionprocess, and others in which the fate of radio-active labeledthylakoid proteins was followed, indicated that the differencebetween the strains lies in the rate of loss of the Dl polypeptidewith an electrophoretic mobility of 32–34 kDa. Both strainsrecovered from the photoinhibition when placed under low PFD.The recovery process started immediately after PFD was reduced,without any observed lag period, and was sensitive to chloramphenicol.Light was required for full recovery of activity. The rate ofrecovery of the two strains studied was very similar. ¹Contribution no. 29 of the Micro-Algal Biotechnology Lab. (Received January 11, 1988; Accepted March 31, 1988)     

Responses of Soybean Leaf Angle, Photosynthesis and Stomatal Conductance to Leaf and Soil Water Potential

The hypothesis that soil water potential (_s) is better correlatedto heliotropic leaf orientation, photosaturated photosyntheticCO₂ assimilation and stomatal conductance during periods oflimited water availability than is bulk leaf water potential(₁) was examined in greenhouse-grown soybean (Glycine max) plants,submitted to a progressive drought. Paired plants were exposedto either 1000 or 100 µmol m^–2 s^–1 photonflux densities (PFD) for 45–60 mins. The higher irradianceinduced short-term decreases in ₁, due to increased transpiration,while _l in the plant exposed to low PFD did not decrease. Thesechanges in ₁ occurred independently of changes in soil waterstatus. Concurrent to the light treatments, a single attachedleaf from each of the two plants was isolated from the restof the plant by shading, and the pulvinus of its terminal leafletwas exposed to a perpendicular PFD of 500 µmol m–²S^–1. Leaf movement of this leaflet was recorded in responseto this light, until a stable leaflet angle was achieved. Valuesof _s and _l (before and after light treatment), and photosaturatedrates of photosynthesis and stomatal conductance, were thenmeasured on these leaves. Leaflet angle and gas exchange werebetter correlated with _s (r² = 0.50, 0.50 and 0.57 for angle,photosynthesis and conductance, respectively) than with _l especiallywhen _l was the result of short-term, high-light induced changesin leaf water status (r² = 0.36, 0.32 and 0.49, for the sameparameters). Leaflet angle was also correlated with stomatalconductance (r² = 0.61) and photosynthetic rate (r² = 0.60),suggesting a close association between leaf orientation, leafmetabolism and soil water availability. Glycine max (L.) Merr. cv. Essex, soybean, heliotropism, water potential, photosynthesis, stomatal conductance, solar tracking     

The effect of cadmium and lead on the growth of two species of marine phytoplankton with particular reference to the development of tolerance

Decreases in salinity (<10%) increased the growth rates ofPhaeodactylum tricornutum and Dunaliella tertiolecta. Increasinglevels of cadmium (1–50 ppm (mg 1^–1)) reduced thegrowth rates of both species. 100 ppm cadmium was lethal toD. tertiolecta but not to P. tricornutum. Lead (1 –4 ppm)initially increased the growth rate of D. tertiolecta but thencaused all but the 1 ppm culture to die. Lead (1–4 ppm)caused a decrease in growth rate of P. tricornutum. After exposureto 1 ppm cadmium, cultures of D. tertiolecta showed an increasedtolerance to levels of cadmium, and a changed response to levelsof lead. Exposure of P. tricornutum to either cadmium or lead,or exposure of D. tertiolecta to lead caused no change in responseto either metal.     

The seasonal productivity of phytoplankton in a hypertrophic, gravel-pit lake

The seasonal time course of phytoplankton primary productivitywas studied weekly in a hypertrophic, gravel-pit lake closeto Madrid, Spain. Chlorophyll a ranged 22–445 mg m^–2.Gross primary productivity attained 0.28±0.14 g C m^–2h^–1 (range: 0.06–0.60), its yearly value being 900g C m^–2, but the shallow euphotic depths and the highplankton respiration ensured that net productivity was generallylow. Respiration losses amounted to 0.31±0.24 g O₂ m^–2h^–1, with phytoplankton respiration roughly attainingone-half of overall plankton respiration. Areal phytoplanktonproductivity and plankton respiration followed a seasonal trendbut this was not the case for photosynthetic capacity. Surfacephotoinhibition was evenly distributed throughout the study.Quantum yields showed an increasing depth trend, but no seasonaltrend. Both P_max and I_k were both temperature- and irradiance-dependent.As compared with lakes of lesser trophic degree, phytoplanktonprimary production in hypertrophic lakes might be increasednot only by higher nutrient contents but also by low chlorophyll-specificattenuation coefficients and low background, non-algal attenuation,thereby allowing for higher areal chlorophyll contents and hencehigher areal productivity. Our study suggests that physical(irradiance and water column stability) as well as chemicalfeatures (dissolved inorganic carbon and soluble reactive phosphorus)may control seasonality of phytoplankton primary productionin this lake despite recent claims that only physical factorsare of significance in hypertrophic lakes. However, this doesnot explain all the variability observed and so a food web controlis also likely to be operating.     

Photoinhibition and the diurnal variation of phytoplankton photosynthesis--I. Development of a photosynthesis--irradiance model from studies of in situ responses

Diurnal series of fluorescence and photosynthesis assays wereconducted in high altitude (3803 m), tropical (16°), LakeTiticaca (Peru/Bolivia). Near-surface diurnal thermoclines formedon typical days of high photon flux density (PFD, {small tilde}2000 µE m^–2 s^–1). In the depth range of diurnalstratification profiles of in vivo fluorescence, both without(F_a and with (F_b DCMU, exhibited a mean decrease of 64% frommorning to mid-day, but little change (mean increase of 1.5%)through the afternoon. Three times during the day surface, mid-depth(3–5 m) and deep (15–20 m) phytoplankton sampleswere incubated with H¹⁴CO₃^– under short (<2 h) exposuresto a range of in situ PFDs. Comparison of phytoplankton in differentsamples (ANOVA) showed identical photosynthetic response insunrise (isothermal) samples but a significant drop in surfaceand mid-depth photosynthesis at all PFDs during times of diurnalstratification. Similarly, both low-light () and light-saturated(P² _max photosynthetic parameters were lower in mid-day surfacesamples compared to deep samples. In addition, previously photoinhibitedsamples had a higher threshold intensity for photoinhibition,I_T. These results, together with diurnal time series of fluorescencefrom in situ incubations, demonstrate that recovery from extendedepisodes of photoinhibition during diurnal stratification isslower than suggested by previous observations in vitro. Photosynthesisby near-surface phytoplankton is different in light increasingup to I_T than light decreasing from I_T. This effect can be modeledby reducing and P_max as a function of the maximum photoinhibitingPFD in the diurnal light history. ¹Present address: Division of Molecular Plant Biology, Universityof California, Berkeley, Berkeley, CA 94720, USA     

Corrigendum

Due to an apparent fault in the telex system, a number of mistakeswere not corrected in this paper. The corrected lines are givenbelow p. 539: line 17In vivo fluorescence action spectra of chl a p. 541: Figure 2 legend, line 92.5 µW cm^–2 at 550nm (0.12 µE m^–2 s^–1 p. 542: Figure 3 legend, line 5( 89 µE m^–2 s^–1).Monochromatic beam intensity was 6 µW cm^–2 at 550nm (–0.28 µE m^–2 s^–1), Figure 3 legend, lines 8 and 9with intensity of 3 mW cm^–2( 179 µE m^–2 s^–1) Monochromatic beam intensitywas 7 5 µW cm^–2 at 550 nm (0.35 µE m^–2s^–1). line 6tivity. The match between the spectra of chl a fluorescenceand PSII O₂ evolution is lines 23–25fluorescence increasingly deviate from thoseof PSII O2 evolution. We attribute this discrepancy to selectivelight scattering by the algae. This scattering increases substantiallywith decreasing wavelength at that region when using a standardspectrofluorometer p. 543: Figure 4 legend, lines 3 and 4as in Chroomonas, withintensity of 2 mW cm^–2 ( 120 µE m^–2 s^–1).Monochromatic beam intensity was 15 µW cm^–2 at 550nm ( 0.7 µE m^–2 s^–1). line 7:ment types in the oceans. While all photoautotrophicorganisms have chl a (the bulk lines 12 and 13:and Barrett (1983). Our spectral data reflectthe great variability in pigment composition and functionalassociation in the major groups of algae. lines 25 and 26:Hiller, 1983). However, blue-violet and redPSII activity is much lower in cryptomonads than might be expectedfrom their absorption spectra (Haxo and Fork, 1958; Haxo, 1960), p. 544: Table I, column 3, entry 6:R-phycocyanin Table 1 legend, lines 1 and 2:^aHaxo and Blinks (1950); ^bFork(1961); ^cHaxo et al. (1955); ^dO'Carra and O'hEocha (1976); ^cresemblesDelesseria decipiens, Haxo and Blinks (1950, Figure 20); ^fHaxoand Fork (1969), like lines 1 and 2:I) indicates that these pigments are affiliatedwith PSII, perhaps exclusively, as in the red algae. In Rhodomonas,the peak of activity at 465 nm may be due to chl c absorp- p. 545: line 2:xanthophyll (fucoxanthin in diatoms, peridininin dinoflagellates and chl c. The ac line 7:shown to be similar to those of the much-studied Chlorella(Vidaver, 1966; Ried, 1972). line 14:tivity of PSII in algae. Spectrofluorometers, with theirsuperior sensitivity and stability, line 34:of natural populations, making these spectra more similarto the PSII photosynthesis lines 36 and 37:Large differences between the values of FIIfor different components within the algal population can distortfluorescence spectra, if they do not correspond with dif lines 41 and 42:different components are not similar to eachother. The necessary handling procedures of natural samples,such as filtration (Yentsch and Yentsch, 1979; Neori et al.,1984), p. 546: lines 20 and 21:DOE contract DE-AT03-82ER60031, anda grant to A.N., O.H.H. and F.T.H. from the Foundation for OceanResearch. Travel to the IInd GAP workshop was facilitated by lines 25 and 26:the culture of Chroomonas, J.Lance for helpwith cultures, J. and E.Yguerabide for the use of their spectrofluorometer,C.R.Booth, Y.Blatt and L.Petrosian for technical line 28:This study was in partial fulfilment for a Ph.D. degreeby A.N. line 42:Dutton.H.J., Manning.W.M. and Duggar.B.M. (1943) Chlorophyllfluorescence and energy transfer in the     

The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation

Prolonged inactivity associated with bed rest in a clinical setting or spaceflight is frequently associated with hypercortisolemia and inadequate caloric intake. Here, we determined the effect of 28 days of bed rest (BR); bed rest plus hypercortisolemia (BRHC); and bed rest plus essential amino acid (AA) and carbohydrate (CHO) supplement (BRAA) on the size and function of single slow- and fast-twitch muscle fibers. Supplementing meals, the BRAA group consumed 16.5 g essential amino acids and 30 g sucrose at 1100, 1600, and 2100 h, and the BRHC subjects received 5 daily doses of 10–15 mg of oral hydrocortisone sodium succinate throughout bed rest. Bed rest induced atrophy and loss of force (mN) and power (µN·FL·s^–1) in single fibers was exacerbated by hypercortisolemia where soleus peak force declined by 23% in the type I fiber from a prevalue of 0.78 ± 0.02 to 0.60 ± 0.02 mN post bed rest (compared to a 7% decline with bed rest alone) and 27% in the type II fiber (1.10 ± 0.08 vs. 0.81 ± 0.05 mN). In the BRHC group, peak power dropped by 19, 15, and 11% in the soleus type I, and vastus lateralis (VL) type I and II fibers, respectively. The AA/CHO supplement protected against the bed rest-induced loss of peak force in the type I soleus and peak power in the VL type II fibers. These results provide evidence that an AA/CHO supplement might serve as a successful countermeasure to help preserve muscle function during periods of relative inactivity. isotonic contractile properties; peak force and power; calcium sensitivity; essential amino acids     

Nitrogen regeneration by the subtropical marine copepod Eucalanus pileatus

Ammonium release rates by individual marine copepods (Eucalanuspileatus) were examined kinetically over successive 10-min intervalsafter the animals were exposed to three concentrations of thediatom Thalassiosira fluviatilis as food. Food concentrationsspanned those expected in the natural environment. "Well-fed"(3 mm³ T. fluviatilis l^–1) copepods released ammoniumsignificantly (p<0.05) faster than those fed zero or lowconcentrations of food, but differences were not dramatic. Meanexcretion rates (± SE) for animals removed from foodfor 18 –22 h [30 ± 6 nmol NH₄(mg ash free dry weight)^–1h ^–1] were 60% of those for "well-fed" animals [49 ±8 nmol NH₄ (mg ash free dry weight)^–1 h^–1]. Continuedhigh release rates after extended periods without food suggestthat E. pileatus must feed frequently in nature to maintainan adequate nitrogen balance. Depending on food concentration,animals released ammonium at rates ranging from 40 to > 100%of their N ingestion rates over the previous 18–22 h.Long-term (4–6 h) kinetic excretion experiments with "well-fed"animals indicated that, on average, release rates decreasedwith time after food removal, but patterns varied among individualcopepods. In addition to ammonium release, o-phthalaldehydereactive amino acid nitrogen was occasionally released by E.pileatus in large "spurt events" lasting from 20 to 60 min. ¹GLERL Contribution No. 283     

Rate of Uptake of Potassium by Three Crop Species in Relation to Growth

Barley, ryegrass, and fodder radish were grown in flowing nutrientsolutions at four potassium concentrations, [K_e⁺], from 0.05to 4 mg I^–1. During the first 2 weeks after germinationthe response to [K_e⁺] (fodder radish > barley > ryegrass)depended on the potential relative growth rate, the ratio ofroot surface area to plant weight, and on the K⁺ flux into theroots. Subsequently, there was no effect of [K_e⁺] on growthrate within the range tested. The K⁺ flux decreased from 4–23? 10^–12 mol cm^–2 s^–1 in the first 2 weeksafter germination, when it was concentration-dependent, to 2–5? 10^–12 mol cm^–2 s^–1 after 4–5 weeks,when it became independent of [K_e⁺] down to 0.05 mg 1^–1.The results explain the importance of high [K_e⁺] and rapid rootgrowth during the first 2 weeks after seed germination.     

Photoadaptation in Antarctic phytopfankton: variations in growth rate, chemical composition and P versus I curves

The response of phytoplankton to variations in the light regimewas studied during the VULCAN and ACDA cruises in the Antarctic.Unenriched batch cultures of 12–19 days' duration reachedchl concentrations of 10–50 µg^–1 and exhibitedexponential growth rates, with the maximal rate being 0.41 doubl,day^–1. Ice edge algae exhibited maximum growth rates atphoton flux densities (PFD) of 30–100 µE m^–2S^–1and the growth rate was reduced by about 30% at 500–1000µE m^–2S^–1 The chl/C ratio ranged between 0.004and 0.018, with the lowest ratios at PFDs above 500 µEm^–2S^–1 chl/C ratios were also below maximum at PFDsbelow 40–50 µE m^–2S^–1 The C:N:P ratioswere close to the Redfield ratios; the Si/C ratio averaged 0.16(atoms), and the ATP/C ratio averaged from 0.0024 to 0.0050in different culture senes. When thawed after having been frozenfor 10 days, shade-adapted cultures were in a much better conditionthan sun-adapted ones. P versus I data showed that the maximumassimilation number varied from 0.75 to 4.4 µg C (µgchl)^–1h^–1. It varied inversely with the chl/C ratio;therefore the maximum carbon turnover rate varied little betweensamples (0.024/0.035 h^–1). Low biomass communities exhibitedrelatively high values for (the initial slope of P versus Icurves), low values for 1_sat (160–330 µE m^–2S^–1),and they were susceptible to photoinhibition. In contrast, communitiesdominated by Odontella weissflogii exhibited low values for, a high value for I_sat (560 µE m^–2S^–1 andthey tolerated high PFDs. The photo-adaptational status of thephytoplankton in natural water samples is discussed relativeto the profile of water column stability and mixing processes.     

Odor sensitivity to geosmin enantiomers

Enantiomers of the earthy smelling odorant ‘geosmin’(t-1, 10-dimethyl-t-9-decalol) were tested on 52 human subjectsfor odor threshold ratio (+)/(–) variability. Thresholdconcentrations of (+) and (–) and their (+)/(–)ratios appeared to be monomodally distributed. For most subjects,the ratio varied within a predictable narrow range comparableto that found previously for carvone enantiomers and contraryto the large variability found for -ionone enantiomers (Polaket al., 1989). The natural occurring isomer, (–) geosminhad, on average an x11 lower threshold than (+).     

Growth and ingestion rates of larval fish populations in the coastal waters of Israel

Clupeoid larvae were collected on eight cruises between February1984 and February 1985 in the coastal waters of Israel. Fromanalysis of daily growth increments of otoliths, growth ratesof the abundant clupeoids, Engraulis encrasicolus, Sardina pilchardusand Sardinella aurita were found to be 0.55 mm day^–1,0.67 mm day^–1 and 0.60 mm day^–1, respectively, duringthe first month after hatching. Ingestion rates were estimatedusing an equation from the literature relating ingestion andgrowth of larval fish. Ingestion calculated for populationsof fish larvae in pelagic waters ranged from 0 to >23 mgC m^–2 day^–1 with maximum rates observed in April.Annual ingestion by larval fish at a pelagic station near Haifawas calculated to be 2.2 g C m^–2 year^–1, 10–20%of annual primary production estimated from ¹⁴C uptake.     

Exploring the role of galectin 3 in kidney function: a genetic approach

Galectin 3 belongs to a family of glycoconjugate-binding proteinsthat participate in cellular homeostasis by modulating cellgrowth, adhesion, and signaling. We studied adult galectin 3null mutant (Gal 3–/–) and wild-type (WT) mice togain insights into the role of galectin 3 in the kidney. Byimmunofluorescence, galectin 3 was found in collecting duct(CD) principal and intercalated cells in some regions of thekidney, as well as in the thick ascending limbs at lower levels.Compared to WT mice, Gal 3–/– mice had ~11% fewerglomeruli (p < 0.04), associated with kidney hypertrophy(p < 0.006). In clearance experiments, urinary chloride excretionwas found to be higher in Gal 3–/– than in WT mice(p < 0.04), but there was no difference in urinary bicarbonateexcretion, in glomerular filtration, or urinary flow rates.Under chronic low sodium diet, Gal 3–/– mice hadlower extracellular fluid (ECF) volume than WT mice (p <0.05). Plasma aldosterone concentration was higher in Gal 3–/–than in WT mice (p < 0.04), which probably caused the observedincrease in -epithelial sodium channel (-ENaC) protein abundancein the mutant mice (p < 0.001). Chronic high sodium dietresulted paradoxically in lower blood pressure (p < 0.01)in Gal 3–/– than in WT. We conclude that Gal 3–/–mice have mild renal chloride loss, which causes chronic ECFvolume contraction and reduced blood pressure levels.     

Midwater macroplankton of British Columbia studied by submersible PISCES IV

Data are reported from 30 dives during winter and spring 1980–83at sites in the Strait of Georgia and inlets running off it,and in inlets on the west coast of Vancouver Island. Observationswere made from the surface to the bottom (maximum 733 m) butmost attention was given to the midwater plankton community.The vertical distribution and abundance of hydromedusae, siphonophores,ctenophores, euphausiids, pelagic worms and molluscs were recordedsystematically, along with data for one copepod species (Neocalanusplumchrus). The midwater environment was found to be stablein terms of species composition and depth ranges, which permittedthe data for several years and many locations to be pooled.Four categories of plankton are recognized: (a) epipelagic (concentratedin the top 50 m); (b) mesopelagic (50–175 m); (c) bathypelagic(below 175 m); and (d) meso-bathypelagic (forms living in bothmeso- and bathypelagic zones). Species in this last categorybehave like mesopelagic forms at the upper end of their ranges,migrating to the surface at night. Deeper-lying members of thesame species do not migrate. For six such species, the cut-offpoint between migratory and non-migratory components was foundto lie at a mean depth of 175 m. This depth is therefore takenas the demarcation point between the meso- and bathypelagiczones. Taking account of published data on light penetration,it is estimated that, for the whole region, daytime light intensityat 175 m, and hence the effective limit for phototaxis of thespecies in question, lies in the range 10^–8–10^–9µW cm^–2.     

A Comparative Study of Disulphide-Bonding and Molecular Weights of Purified Fractions from Secalin, Gliadin, and Hordein

Prolamin polypeptides from rye, wheat, and barley were comparedwith respect to the nature of their disulphide bonds, the effectsof reduction, and their molecular weights. Most secalins weredistinguished by their ease of reduction to polypeptides ofintermediate mobility, ranging in size from about 82–92kilodaltons (Kd), or to polypeptides with molecular weightsof 38 Kd that migrated 20–25% slower upon reduction. Athird group of secalin components had intermediate electrophoreticmobility on lactate gels, were unaffected by reducing agentsand had a molecular weight of 48 Kd. Wheat gliadin fractionscontained two types of component: the w-gliadins that couldnot be reduced further and the -, ß-, or -gliadinswhich were reduced to polypeptides of slightly lower electrophoreticmobilities than their native precursors. The predominant molecularweight range of gliadin polypeptides was 33–37 Kd. Thepredominant polypeptide components of hordein were nonreducible,with apparent molecular weights in the range from 50–60Kd. Few secalin or hordein polypeptides were similar in bothsize and reactivity to the gliadins. Key words: Secalin, Hordein, Gliadin, Molecular weight, Disulphide bond