Photosynthesis and growth rates of Laurencia brongniartii J. Agardh (Rhodophyta, Ceramiales) in preparation for cultivation

Laurencia brongniartii is usually found at depths below 4 m, but can be found in shallow subtidal areas in crevices and on the walls of a coral reef in Amami Oshima Island, Kagoshima Prefecture, Japan, where irradiances were significantly lower than those at similar depths in open water. In preparation for the possible cultivation of this species for its antibiotic compounds, the effects of temperature and irradiance on photosynthesis and growth were measured. Photosynthesis and growth rates of L. brongniartii explants were highest at 26 and 28 °C, which closely corresponded to temperatures found during August to late December when it was most abundant. The estimated maximum photosynthesis rate (P _max) was 4.41 mol photon m^–2 s^–1 at 26 °C and 4.07 mol photon m^–2 s^–1 at 28 °C. Saturating irradiance occurred at 95 mol photon m^–2 s^–1 at 26 °C and 65 mol photon m^–2 s^–1 at 28 °C. In contrast, growth experiments at 41.7 mol photon m^–2 s^–1 caused bleaching of explants and the maximum growth rate observed during the study was 3.02 ± 0.75% day^–1 at 28 °C and 25 mol photon m^–2 s^–1. The difference in the saturating irradiance for photosynthesis and the irradiance that caused bleaching in growth experiments suggests that long-term exposure to high irradiance was detrimental and should be addressed before the initiation of large scale cultivation.     

Light response of D1 turnover and photosystem II efficiency in the seagrassZostera capricorni

Biochemical and biophysical parameters, including D1-protein turnover, chlorophyll fluorescence, oxygen evolution activity and zeaxanthin formation were measured in the marine seagrassZostera capricorni (Aschers) in response to limiting (100 mol·m^–2·^–1), saturating (350 mol·m^–2·s^–1) or photoinhibitory (1100 mol·m^–2·s^–1) irradiances. Synthesis of D1 was maximal at 350 mol·m^–2·s^–1 which was also the irradiance at which the rate of photosynthetic O₂ evolution was maximal. Degradation of D1 was saturated at 350 mol·m^–2·s^–1. The rate of D1 synthesis at 1100 mol·m^–2·s^–1 was very similar to that at 350 mol·m^–2·s^–1 for the first 90 min but then declined. At limiting or saturating irradiance little change was observed in the ratio of variable to maximal fluorescence (Fv/Fm) measured after dark adaptation of the leaves, while significant photoinhibition occurred at 1100 mol·m^–2·s^–1. The proportion of zeaxanthin in the total xanthophyll pool increased with increasing irradiance, indicative of the presence of a photoprotective xanthophyll cycle in this seagrass. These results are consistent with a high level of regulatory D1 turnover inZostera under non-photoinhibitory irradiance conditions, as has been found previously for terrestrial plants.We would like to thank Professor Peter Böger (Department of Plant Biochemistry, University of Konstanz, Germany) for the kind gift of D1 antibodies. This work was partly supported by a University of Queensland Enabling Grant to CC.     

Utilisation of soil organic P by agroforestry and crop species in the field,western Kenya

A field experiment in western Kenya assessed whether the agroforestry species Tithonia diversifolia (Hemsley) A. Gray, Tephrosia vogelii Hook f., Crotalaria grahamiana Wight & Arn. and Sesbania sesban (L) Merill. had access to forms of soil P unavailable to maize, and the consequences of this for sustainable management of biomass transfer. The species were grown in rows at high planting density to ensure the soil under rows was thoroughly permeated by roots. Soil samples taken from beneath rows were compared to controls, which included a bulk soil monolith enclosed by iron sheets within the tithonia plot, continuous maize, and bare fallow plots. Three separate plant biomass samples and soil samples were taken at 6-month intervals, over a period of 18 months. The agroforestry species produced mainly leaf biomass in the first 6 months but stem growth dominated thereafter. Consequently, litterfall was greatest early in the experiment (0–6 months) and declined with continued growth. Soil pH increased by up to 1 unit (from pH 4.85) and available P increased by up to 38% (1 g P g^–1) in agroforestry plots where biomass was conserved on the field. In contrast, in plots where biomass was removed, P availability decreased by up to 15%. Coincident with the declines in litterfall, pH decreased by up to 0.26 pH units, plant available P decreased by between 0.27 and 0.72 g g^–1 and P_o concentration decreased by between 8 and 35 g g^–1 in the agroforestry plots. Declines in P_o were related to phosphatase activity (R²=0.65, P<0.05), which was greater under agroforestry species (0.40–0.50 nmol MUB s^–1 g^–1) than maize (0.28 nmol MUB s^–1 g^–1) or the bare fallow (0.25 nmol MUB s^–1 g^–1). Management of tithonia for biomass transfer, decreased available soil P by 0.70 g g^–1 and P_o by 22.82 g g^–1. In this study, tithonia acquired P_o that was unavailable to maize. However, it is apparent that continuous cutting and removal of biomass would lead to rapid depletion of P stored in organic forms.     

Ex Vitro Phenotype Stability is Affected by In Vitro Cultivation

Plant phenotype stability during ex vitro growth, one of the main requirements of plant micropropagation, was tested on tobacco. Plants cultivated in vitro in the presence of 3 % sucrose under photon flux density (PFD) of 200 mol m^–2 s^–1 (3 % HL plants) showed the best growth and photosynthetic parameters in the course of 7-day acclimation. However, significant change in phenotype of these plants appeared under a decrease in PFD to 50 mol m^–2 s^–1 during further ex vitro growth (in the period of 7^th – 17^th day). Much higher internodia elongation was found in 3 % HL plants in comparison with plants grown in vitro on sucrose media under PFD of 50 mol m^–2 s^–1 (3 % LL) or without sucrose either under PFD of 50 mol m^–2 s^–1 or 200 mol m^–2 s^–1 (0 % LL, 0 % HL). It can be presumed that 3 % HL plants show permanent demand for high PFD. Neither ABA or chlorophyll contents nor de novo thylakoid membrane synthesis were related to the morphogenic effect of low PFD. Changeable contents of hexoses in leaves of 3 % HL and 3 % LL plants were in no direct correlation to the elongated growth.     

Ecophysiological characterization of carnivorous plant roots: Oxygen fluxes,respiration, and water exudation

Various ecophysiological investigations on carnivorous plants in wet soils are presented. Radial oxygen loss from roots of Droseraceae to an anoxic medium was relatively low 0.02 – 0.07 mol(O₂) m^{– 2} s^–1 in the apical zone, while values of about one order of magnitude greater were found in both Sarracenia rubra roots and Genlisea violacea traps. Aerobic respiration rates were in the range of 1.6 – 5.6 mol kg^–1 (f.m.) s^–1 for apical root segments of seven carnivorous plant species and 0.4 – 1.1 mol kg^–1 (f.m.) s^–1 for Genlisea traps. The rate of anaerobic fermentation in roots of two Drosera species was only 5 – 14 % of the aerobic respiration. Neither 0.2 mM NaN₃ nor 0.5 mM KCN influenced respiration rate of roots and traps. In all species, the proportion of cyanide-resistant respiration was high and amounted to 65 – 89 % of the total value. Mean rates of water exudation from excised roots of 12 species ranged between 0.4 – 336 mm 3 kg^–1 (f.m.) s^–1 with the highest values being found in the Droseraceae. Exudation from roots was insensitive to respiration inhibitors. No significant difference was found between exudation rates from roots growing in situ in anoxic soil and those kept in an aerated aquatic medium. Carnivorous plant roots appear to be physiologically very active and well adapted to endure permanent soil anoxia.     

Effects of copper on algal communities at different current velocities

This study examines the influence of current velocity in the toxiceffect of copper in diatom-dominated biofilms grown in artificial channels.Effects on community structure, algal biomass and photosynthesis (carbonincorporation) caused by 15 g L^–1 of copperwere tested at contrasting (1 and 15 cm s^–1)velocities. Moreover, a possible threshold on the effect of copper on algalbiomass and photosynthesis related to current velocity was examined by usingprogressively increasing current velocity (1 to 50 cms^–1) at 15 g L^–1 Cu.Chlorophyll-a decreased ca. 50% as a result of addition of15 g L^–1 Cu. Chlorophyll decrease occurredearlier at 15 cm s^–1 than at 1 cms^–1 when adding 15 g L^–1Cu. Copper also caused a remarkable decrease in carbon incorporation(from 30 to ca. 50%), which was produced earlier at 15 cms^–1 (three days) than at 1 cms^–1 (seven days). Some taxa were affected by thecombination of copper and current velocity. Both Achnanthesminutissima and Stigeoclonium tenue becomedominant at 15 cm s^–1 in the presence of copper.Significant inhibition of algal growth in 15 g L^–1Cu occurred at low (1 cm s^–1) and highvelocities (50 cm s^–1), but not at intermediatevelocity (20 cm s^–1). The experiments indicatethat current velocity triggers the effect that copper has on diatom-dominatedbiofilms, and that the effect is more remarkable at low and high than atintermediate current velocities.     

Seasonal CO<Subscript>2</Subscript>-exchange variations of temperate semi-desert grassland in Hungary

CO₂ exchange components of a temperate semi-desert sand grassland ecosystem in Hungary were measured 21 times in 2000–2001 using a closed IRGA system. Stand CO₂ uptake and release, soil respiration rate (R _s), and micrometeorological values were determined with two types of closed system chambers to investigate the daily courses of gas exchange. The maximum CO₂ uptake and release were –3.240 and 1.903 mol m^–2 s^–1, respectively, indicating a relatively low carbon sequestration potential. The maximum and the minimum R _s were 1.470 and 0.226 mol(CO₂) m^–2 s^–1, respectively. Water shortage was probably more effective in decreasing photosynthetic rates than R _s, indicating water supply as the primary driving variable for the sink-source relations in this ecosystem type.     

Seasonality of brown macroalgae from Antarctica—a long-term culture study under fluctuating Antarctic daylengths

Summary The seasonal development of the endemic Antarctic Desmarestiales Himantothallus grandifolius, Phaeurus antarcticus, Desmarestia anceps, of a ligulate Desmarestia sp., of the Antarctic cold-temperate Adenocystis utricularis (Dictyosiphonales) and of the endemic Antarctic Ascoseira mirabilis (Ascoseirales) was monitored in a 2-year culture study under fluctuating daylengths mimicking the daylength conditions on King George Island (Antarctica). Temperature was kept constant at 0° C and nutrient levels were maintained at 0.6 moles m^–3 nitrate and 0.025 moles m ^–3 phosphate. Sporophytes were initiated between (April-) June and July in all Desmarestiales. This event was controlled either by induction of gametophyte fertility (in H. grandifolius and D. anceps) or by induction of spore formation (in Desmarestia sp. and P. antarcticus). Young sporophytes of all species showed a growth optimum from September to December (-February). Desmarestia sp. and P. antarcticus produced spores and degenerated subsequently after one year of culture at 3 mol photons m^–2 s^–1 or after 22 months of culture at 2 mol m^–2 s^–1. In D. anceps spores were released without degeneration of the mother plants after 20 and 19 months of culture at 3 and 10 olm^–2 s^–1, respectively. In H. grandifolius spore formation was not observed. Adult one year old plants of the latter two perennial species showed growth optima between September and November. Microthalli of A. utricularis were the dominant life phase of this alga in winter. Macrothalli started to develop from June onwards at 3 mol m^–2 s^–1 or from August to September at 2 mol m^–2 s^–1. Growth rates of macrothalli cultivated at 9 mol m^–2 s^–1 showed a growth optimum from September to November. The macrothalli released spores from January to February. Macrothalli cultivated at 3 mol m^–2 s^–1 maximally grew in January. They became fertile after almost 2 years of culture at 3 mol m^–2 s^–1 and remained vegetative at 2 mol m^–2 s^–1. A. mirabilis exhibited a prominent growth optimum from August to October, at photon fluence rates between 2 and 47 mol m^–2 s^–1. A second optimum was evident from January to March in plants cultivated at 9 mol m^–2 s^–1. The results closely correspond to available field data and indicate that the phenology of the studied species can be controlled in the laboratory solely by simulating Antarctic daylengths conditions. The light requirements for growth were very low in microthalli and in juvenile macrothalli and growth was mostly light saturated at 4–12 mol m^–2 s^–1. Few-celled sporophytes of H. grandifolius and D. anceps tolerated at least 8 and 11 months of darkness. The minimum light demands for completion of the life cycle are 31.4 mol m^–2 year^–1 in Desmarestia sp., P. antarcticus and probably also in the 2 perennial Desmarestiales; 47.1 mol m^–2 year^–1 are needed in A. utricularis and probably also in A. mirabilis. These values predict a lower distribution limit of the investigated species at 53±23 m or 48±21 m in clear offshore waters and at 28±5 m or 26±5 m, respectively, in inshore fjords of the Antarctic Peninsula region.Contribution No. 281 of the Alfred-Wegener-Institut für Polar-u. Meeresforschung     

An extracellular sulfated fucose-rich polysaccharide produced by a tropical strain of Cryptomonas obovata (Cryptophyceae)

A tropical strain of Cryptomonas obovata Skuja, isolated from a shallow oxbow lake,releaseda sulfated fucose-rich polysaccharide. The polysaccharide is composed mainly offucose (42%), N-acetyl-galactosamine (26%) and rhamnose (15%), with smallquantities of glucuronic acid, mannose, galactose, xylose and glucose. Sulfateaccounted for 1.7% total polysaccharide. Quantitative release was studied withcells exposed to optimal culture conditions contrasted with high irradiance andnitrate depletion. This latter set of conditions could simulate stresssituations usually found in the place from which this strain was isolated. Themonosaccharide composition of the polysaccharide was evaluated using PAD-HPLCand gas chromatography. The two irradiances tested (165 molm^–2 s^–1 and 2000 molm^–2 s^–1) had no significant effect onamounts of polysaccharide released by the cells. Differences were observed whenthe nitrate availability was varied. In the nitrate-depleted situation,extracellular polysaccharide production was 2.5 times higher than replete cellsafter 6 h at 165 mol m^–2s^–1, and 2.25 times higher at 2000 molm^–2 s^–1.     

Chlorophyll fluorescence as an indicator of photosynthetic functioning of in vitro grapevine and chestnut plantlets under ex vitro acclimatization

This study reports the effects of light availability during the acclimatization phase on photosynthetic characteristics of micropropagated plantlets of grapevine (Vitis vinifera L.) and of a chestnut hybrid (Castanea sativa × C. crenata). The plantlets were acclimatized for 4 weeks (grapevine) or 6 weeks (chestnut), under two irradiance treatments, 150 and 300 mol m^–2 s^–1 after in vitro phases at 50 mol m^–2 s^–1. For both treatments and both species, leaves formed during acclimatization (so-called `new leaves') showed higher photosynthetic capacity than the leaves formed in vitro either under heterotrophic or during acclimatization (so-called `persistent leaves'), although lower than leaves of young potted plants (so-called `greenhouse leaves'). In grapevine, unlike chestnut, net photosynthesis and biomass production increased significantly with increased light availability. Several parameters associated with chlorophyll a fluorescence indicated photoinhibition symptoms in chestnut leaves growing at 300 mol m^–2 s^–1. The results taken as a whole suggest that 300 mol m^–2 s^–1 is the upper threshold for acclimatization of chestnut although grapevine showed a better response than chestnut to an increase in light.     

Effects of Cd and Zn on the development of annual xylem rings of young Norway spruce (Picea abies) plants

Three-year-old spruce (Picea abies) saplings were planted and cultivated for 2 years in pots with 3 1 substrate, consisting of a homogenized mixture of sand, peat and forest soil with a high organic content (volume ratio 11.52). This substrate was amended with 10–180 mol Cd [kg soil dry weight (DW)]^–1, 50–7500 mol Zn (kg soil DW)^–1 (determined with 1 M ammonium acetate extracts) or combinations of both elements. Annual xylem growth rings in stems of plants treated with 50 mol Cd (kg soil DW)^–1 or 7500 mol Zn (kg soil DW)^–1 were significantly narrower than in control plants. Growth reductions were more pronounced in the second year of the experiment. The contents of Cd and Zn in stem wood and needles were positively correlated with the substrate concentrations. The Mg contents of the spruce needles were inversely correlated with soil concentrations of Cd and Zn. Root development was impeded at moderate concentrations of Cd (50 mol kg^–1) or Zn (1000 mol kg^–1) in the substrate. The adverse effects of potentially toxic trace elements, like Cd or Zn, on xylem growth of spruce plants are discussed with regard to possible growth reductions in forest trees under field conditions.     

In vitro multiplication of Quercus leucotrichophora and Q. glauca: Important Himalayan oaks

Multiple shoots of Quercus leucotrichophora L. and Q. glauca Thunb. were induced from the intact embryos (decoated seeds) as well as from the cotyledonary nodes (with attached cotyledons but without radicle and primary shoot) of 3-weeks old in vitro grown seedlings on Woody Plant (WP; Lloyd and McCown, 1980) and Murashige and Skoog (MS; 1962) media supplemented with 6-benzyladenine (BA), either alone or in combination with gibberellic acid (GA₃)/ indole-3-butyric acid (IBA). BA (22.19 M) was effective for induction of multiple shoots and addition of GA₃ to the medium further enhanced the shoot number and shoot height but resulted in shoot thinness. High frequency shoot multiplication was achieved using cotyledonary nodes. Shoots were further multiplied from the original explant on WP medium supplemented with BA (22.19 M). Nearly 78% and 67% rooting was obtained in Q. leucotrichophora and Q. glauca microshoots (3–4 cm high), respectively on 1/2 strength WP medium supplemented with IBA (14.76 M). However, this was associated with basal callus formation. Treatment with IBA (25–100 M) for 24 or 48 h followed by transfer to PGR free 1/2 strength WP medium not only improved the rooting percentage but also avoided basal callus formation. IBA at 100 M for 24 h was most effective (90% and 100% rooting in Q. leucotrichophora and Q. glauca, respectively). In vitro rooted plants were hardened and established in garden soil.Growth performance of 6-month-old in vitro raised plants was compared with ex vitro plants (seedlings) of the same age. The photosynthesis and transpiration rates of eight months old in vitro and ex vitro raised plants of both species were measured under different light (0, 600, 900, 1200, 1500 and 2000 mol m^–2s^–1) and temperature (20, 25, 30, 35 and 40 °C). Light optimum for photosynthesis was around 2000 mol m^–2s^–1 in Q. leucotrichophora and around 1500 mol m^–2s^–1 in Q. glauca whereas optimum temperature for photosynthesis was 25 °C in Q. leucotrichophora and 30 °C in Q. glauca. The rate of transpiration at different temperatures (20–40 °C), in the two species, increased with increase in the light intensity up to the highest level, i.e., 2000 mol m^–2s^–1. Temperatures beyond 35 °C adversely affected the rate of transpiration in in vitro raised as well as ex vitro plants of both the species. In vitro raised and hardened plants of both the species were comparable to ex vitro plants in terms of gas and water vapour exchange characteristics, within the limits of this study.     

Response of maize and rice to 9-β-L(+) adenosine applied under different environmental conditions

The increase in growth, determined by dry weight gain, of rice (Oryza sativa L.) and maize (Zea mays L.) caused by foliar applications of 9--L(+) adenosine, a putative second messenger elicited by triacontanol, was studied under different environmental conditions. Maize seedlings cultured in the greenhouse under approximately 100 mol m^–2s^–1 of light prior to treatment with L(+) adenosine did not respond unless they received supplemental light (250–300 mol m^–2s^–1) after treatment. Exposure of rice seedlings growing for 16 h at 150 mol m^–2s^–1 to short periods of 450 mol m^–2s^–1 (< than 20 min) had no effect on the positive response of rice to L(+) adenosine; however, exposure for 60 min or more increased the growth of rice and obviated the effect of L(+) adenosine. Rice seedlings treated with L(+) adenosine at different times during the day responded only when treated 9 to 12h after initiation of the photoperiod. Normal growing temperatures under different light intensities had little or no direct effect on the response of plants to L(+) adenosine.     

Gas Exchange of Carrot Leaves in Response to Elevated CO2 Concentration

Short-term responses of four carrot (Daucus carota) cultivars: Cascade, Caro Choice (CC), Oranza, and Red Core Chantenay (RCC) to CO₂ concentrations (C _a) were studied in a controlled environment. Leaf net photosynthetic rate (P _N), intercellular CO₂ (C _i), stomatal conductance (g _s), and transpiration rate (E) were measured at C _a from 50 to 1 050 mol mol^–1. The cultivars responded similarly to C _a and did not differ in all the variables measured. The P _N increased with C _a until saturation at 650 mol mol^–1 (C _i= 350–400 mol mol^–1), thereafter P _N increased slightly. On average, increasing C _a from 350 to 650 and from 350 to 1 050 mol mol^–1 increased P _N by 43 and 52 %, respectively. The P _N vs. C _i curves were fitted to a non-rectangular hyperbola model. The cultivars did not differ in the parameters estimated from the model. Carboxylation efficiencies ranged from 68 to 91 mol m^–2 s^–1 and maximum P _N were 15.50, 13.52, 13.31, and 14.96 mol m^–2 s^–1 for Cascade, CC, Oranza, and RCC, respectively. Dark respiration rate varied from 2.80 mol m^–2 s^–1 for Oranza to 3.96 mol m^–2 s^–1 for Cascade and the CO₂ compensation concentration was between 42 and 46 mol mol^–1. The g _s and E increased to a peak at C _a= 350 mol mol^–1 and then decreased by 17 and 15 %, respectively when C _a was increased to 650 mol mol^–1. An increase from 350 to 1 050 mol mol^–1 reduced g _s and E by 53 and 47 %, respectively. Changes in g _s and P _N maintained the C _i:C _a ratio. The water use efficiency increased linearly with C _a due to increases in P _N in addition to the decline in E at high C _a. Hence CO₂ enrichment increases P _N and decreases g _s, and can improve carrot productivity and water conservation.     

Effect of dilution rate on the release of pertussis toxin and lipopolysaccharide ofBordetella pertussis

Summary The kinetics ofBordetella pertussis growth was studied in a glutamate-limited continuous culture. Growth kinetics corresponded to Monod's model. The saturation constant and maximum specific growth rate were estimated as well as the energetic parameters, theoretical yield of cells and maintenance coefficient. Release of pertussis toxin (PT) and lipopolysaccharide (LPS) were growth-associated. In addition, they showed a linear relationship between them. Growth rate affected neither outer membrane proteins nor the cell-bound LPS pattern.Nomenclature X cell concentration (g L^–1) - specific growth rate (h^–1) - _m maximum specific growth rate (h^–1) - D dilution rate (h^–1) - S concentration of growth rate-limiting nutrient (glutamate) (mmol L^–1 or g L^–1) - Ks substrate saturation constant (mol L^–1) - m_s maintenance coefficient (g g^–1 h^–1) - Y_x/s theoretical yield of cells from glutamate (g g^–1) - Y_x/s yield of cells from glutamate (g g^–1) - Y_PT/s yield of soluble PT from glutamate (mg g^–1) - Y_KDO/s yield of cell-free KDO from glutamate (g g^–1) - Y_PT/x specific yield of soluble PT (mg g^–1) - Y_KDO/x specific yield of cell-free KDO (g g^–1) - q_PT specific soluble PT production rate (mg g^–1 h^–1) - q_KDO specific cell-free KDO production rate (g g^–1 h^–1)     

Characteristics of transient photosynthesis in Quercus serrata seedlings grown under lightfleck and constant light regimes

Photosynthetic-induction response and light-fleck utilization were investigated for the current-year seedlings of Quercus serrata, a deciduous tree found in temperate regions of Japan. The tree seedlings were grown under three light regimes: a constant low photosynthetic photon flux density (PFD) regime of 50 mol m^–2 s^–1, a constant high PFD regime of 500 mol m^–2 s^–1, and a lightfleck regime with alternated low (lasting 5 s) and high (lasting 35 s) PFD. The photosynthetic-induction response following a sudden increase of PFD from 50 to 500 mol m^–2 s^–1 exhibited two phases: an initial fast increase complete within 3–5 s, and a second slow increase lasting for 15–20 min. Induction times required to reach 50% and 90% of steady-state assimilation rates were significantly shorter in leaves from the constant low PFD than those from the high PFD regime. During the first 60–100 s, the ratio of observed integrated CO₂ uptake to that predicted by assuming that a steady-state assimilation would be achieved instantaneously after the light increase was significantly higher for leaves from the low PFD regime than from the high PFD regime. Lightfleck utilization was examined for various durations of PFD of 500 mol m^–2 s^–1 on a background PFD of 50 mol m^–2 s^–1. Lightfleck utilization efficiency was significantly higher in low PFD leaves than in the high PFD leaves for 5-s and 10-s lightflecks, but showed no difference among different light regimes for 100-s lightflecks. The contribution of post-illumination CO₂ fixation to total carbon gain decreased markedly with increasing lightfleck durations, but exhibited no significant difference among growth regimes. Photosynthetic performances of induction response and lightfleck utilization in leaves from the lightfleck regime were more similar to those in leaves from the low PFD regime. It may be the total daily PFD rather than PFD dynamics in light regimes that affects the characteristics of transient photosynthesis in Q. serrata seedlings.     

Isolation of membrane bound light-harvesting-complexes from the dinoflagellates Heterocapsa pygmaea and Prorocentrum minimum

We have isolated Chl a-Chl c-carotenoid binding proteins from the dinoflagellates Prorocentrum minimum and Heterocapsa pygmaea grown under high (500 mol m^–2 s^–1, HL) and low (35 mol m^–2 s^–1, LL) light conditions. We compared various isolation procedures of membrane bound light harvesting complexes (LHCs) and assayed the functionality of the solubilized proteins by determining the energy transfer efficiency from the accessory pigments to Chl a by means of fluorescence excitation spectra. The identity of the newly isolated protein-complexes were confirmed by immunological cross-reactions with antibodies raised against the previously described membrane bound Chl a-c proteins (Boczar et al. (1980) FEBS Lett 120: 243–247). Spectroscopic analysis demonstrated the relatedness of these proteins with the recently described Chl-a-c ₂-peridinin (ACP) binding protein (Hiller et al. (1993) Photochem Photobiol 57: 125–131; Iglesias Prieto et al. (1993) Phil Trans R Soc London B 338: 381–392). The water-soluble peridinin-Chl a binding-protein (PCP) was not detectable in P. minimum. Two functional forms of ACP with different pigmentation were isolated. A variant of ACP which was isolated from high-light grown cells, that specifically binds increased amounts of diadinoxanthin was compared to the previously described ACPs that bind proportionately more peridinin.Abbreviations ACP Chl a-Chl c-peridinin binding protein - AEBSF 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride - DDM dodecyl -d maltoside - Deriphat 160 N-lauryl-beta-iminopropionic acid - HEPES (N-2-hydroxyethylpiparizine-N-2-ethanesulphonic acid) - HL high light (500 mol m^–2 s^–1) - LL low light (35 mol m^–2 s^–1) - ₇₃₀ fluorescence yield (emission at 730 nm) - PCP peridinin-Chl a-binding protein - PMSF phenyl-methyl-sulfonyl-fluoride - PS I Photosystem I - PS II Photosystem II     

Growth and betacyanin production by hairy roots of Beta vulgaris in airlift bioreactors

Hairy roots of red beet (Beta vulgaris L.) were cultivated in different types of airlift bioreactors (cone, balloon, bulb, drum and column bioreactors of 5 l capacity and containing 3 l of half strength Murashige & Skoog medium). The cone type of airlift bioreactor gave the highest biomass of hairy roots and betacyanin accumulation. Betacyanin accumulation was 27 mg g^–1 dry wt in cultures aerated at 0.3 vvm. Light irradiation of 20 mol m^–2 s^–1 promoted hairy root growth but optimum betacyanin (34 mg g^–1 dry wt) accumulation was with the cultures grown under 60 mol m^–2 s^–1.     

Reactivation of photosynthesis in the photoinhibited green alga Chlamydomonas reinhardtii: Role of dark respiration and of light

Effect of quality, quantity and minimum duration of light on the process of recovery was investigated in the photoinhibited cells of the green alga Chlamydomonas reinhardtii. Complete and rapid reactivation of photosynthesis took place in diffuse white light of 25 mol m^–2 s^–1. The recovery was partial (< 10%) in the dark. Far red (725 nm), red (660 nm) and blue light (480 nm) in the range of 10 to 75 mol m^–2 s^–1 did not enhance the process of reactivation. Photoinhibited cells incubated in dark for 15 min when exposed for 5 min to diffuse light (25 mol m^–2 s^–1) showed complete reactivation. Even exposure of 15 min dark incubated photoinhibited cells to photoinhibitory light (2500 mol m^–2 s^–1) for 5 s fully regained the photosynthesis. The study indicated a very precise and triggering effect of light in the process of reactivation. The dark respiratory inhibitor KCN and uncouplers FCCP and CCCP increased the susceptibility of C. reinhardtii to photoinhibition and also prevented photoinhibited cells to reactivate fully even after longer period of incubation under suitable reactivating conditions. Of the various possibilities envisaged to assign the role of dark respiration in recovery process, supply of ATP by mitochondrial respiration appeared sound and pertinent.Abbreviations CCCP- carbonyl cyanide m-chlorophenylhydrazone - D1- 32 kDa protein of PS II reaction center - FCCP- carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone - KCN- potassium cyanide - PBQ- phenyl-p-benzoquinone - PFD- photon flux density - SHAM- salicylhydroxamic acid NBRI Research Publication No. 431.     

Arsenic concentrations in water and fish from Chautauqua Lake,New York

Synopsis Arsenic persists in Chautauqua Lake, New York waters 13 years after cessation of herbicide (sodium arsenite) application and continues to cycle within the lake. Arsenic concentrations in lake water ranged from 22.4–114.81 g l^–1, = 49.0 ag l^–1. Well water samples generally contained less than 10 g l^–1 arsenic. Arsenic concentrations in lake water exceeded U.S. Public Health Service recommended maximum concentrations (10 g l^–1) and many samples exceeded the maximum permissible limit (50 g l^–1). Fish accumulated arsenic from water but did not magnify it. Fish to water arsenic ratios ranged from 0.4–41.6. Black crappie (Pomoxis nigromaculatus) contained the highest arsenic concentrations (0.14–2.04 g g^–1 ), X = 0.7 g g^–1) while perch (Perca flavescens), muskellunge (Esox masquinongy) and largemouth bass (Micropterus salmoides) contained the lowest concentrations (0.02–0.13 g g^–1). Arsenic concentrations in fish do not appear to pose a health hazard for human consumers.