Primary production,respiration and calcification of the temperate free-living coralline alga Lithothamnion corallioides

Calcification and primary production responses to irradiance in the temperate coralline alga Lithothamnion corallioides were measured in summer 2004 and winter 2005 in the Bay of Brest. Coralline algae were incubated in dark and clear bottles exposed to different irradiances. Net primary production reached 1.5 μmol C g⁻¹ dry wt h⁻¹ in August and was twice as high as in January–February. Dark respiration showed significant seasonal variations, being three-fold higher in summer. Maximum calcification varied from 0.6 μmol g⁻¹ dry wt h⁻¹ in summer 2004 to 0.4 μmol g⁻¹ dry wt h⁻¹ in winter 2005. According to P–E curves and the daily course of irradiance, estimated daily net production and calcification reached 131 μg C g⁻¹ dry wt and 970 μg CaCO₃ g⁻¹ dry wt in summer 2004, and 36 μg C g⁻¹ dry wt and 336 μg CaCO₃ g⁻¹ dry wt in winter 2005. The net primary production of natural L. corallioides populations in shallow waters was estimated at 10–600 g C m⁻² y⁻¹, depending on depth and algal biomass. The mean annual calcification of L. corallioides populations varied from 300 to 3000 g CaCO₃ m⁻². These results are similar to those reported for tropical coralline algae in terms of carbon and carbonate productivity. Therefore, L. corallioides can be considered as a key element of carbon and carbonate cycles in the shallow coastal waters where they live.     

Crystal structures and chemical composition of leaf surface wax depositions on the desert moss Syntrichia caninervis

The structures and composition of cuticular waxes deposited on the leaves of a typical desert moss, Syntrichia caninervis, were investigated. The wax crystals deposited on leaves shifted with leaf aging. The results of chemical analysis showed the main chemical components of the moss wax were fatty acids, alcohols and alkanes. Leaf aging increased the content of cuticular wax and the percentage of very long chain components, from 1150 μg g⁻¹ DW and 13.6% in younger leaves to 2640 μg g⁻¹ DW and 37.2% in aged leaves, respectively. Dehydration/hydration also augmented the wax content by 35.17% in juvenile leaves and by 1900% in lab-cultivated leaves after three-cycle treatments. Synthesis of hexadecanoic acid and tetracosane were predicted to be the first step of wax accumulation. The responses of cuticular waxes in crystal structure and chemical composition were recommended as a biomonitor for assessing the shift of ecological and environmental quality.     

In silico optimization and low structured kinetic model of poly[(R)-3-hydroxybutyrate] synthesis by Cupriavidus necator DSM 545 by fed-batch cultivation on glycerol

Glycerol was utilized by Cupriavidus necator DSM 545 for production of poly-3-hydroxybutyrate (PHB) in fed-batch fermentation. Maximal specific growth rates (0.12 and 0.3 h⁻¹) and maximal specific non-growth PHB production rate (0.16 g g⁻¹ h⁻¹) were determined from two experiments (inocula from exponential and stationary phase). Saturation constants for nitrogen (0.107 and 0.016 g L⁻¹), glycerol (0.05 g L⁻¹), non-growth related PHB synthesis (0.011 g L⁻¹) and nitrogen/PHB related inhibition constant (0.405 g L⁻¹), were estimated. Five relations for specific growth rate were tested using mathematical models. In silico performed optimization procedures (varied glycerol/nitrogen ratio and feeding) has resulted in a PHB content of 70.9%, shorter cultivation time (23 h) and better PHB yield (0.347 g g⁻¹). Initial concentration of biomass 16.8 g L⁻¹ and glycerol concentration in broth between 3 and 5 g L⁻¹ were decisive factors for increasing of productivity.     

Light-dependent phosphate uptake of a submersed macrophyte Myriophyllum spicatum L.

The uptake kinetics of phosphate (Pi) by Myriophyllum spicatum was determined from adsorption and absorption under light and dark conditions. Pi uptake was light dependent and showed saturation following the Michaelis-Menten relation (in light: V = 16.91 × [Pi](1.335 + [Pi]), R² = 0.90, p < 0.001; in the dark: V = 5.13 × [Pi](0.351 + [Pi]), R² = 0.77, p < 0.001). Around 77% of the loss of Pi in the water column was absorbed into the tissue of M. spicatum, and only 23% was adsorbed on the surface of the plant shoots. Our study shows that M. spicatum shoots have a much higher affinity (in light: 3.9 μmol g⁻¹ dw h⁻¹ μM⁻¹; in the dark: 3.7 μmol g⁻¹ dw h⁻¹ μM⁻¹) and V_max (maximum uptake rate, shoot light) for Pi uptake than many other aquatic macrophytes (in light: 0.002-0.23 μmol g⁻¹ dw h⁻¹ μM⁻¹; in the dark: 0.002-0.19 μmol g⁻¹ dw h⁻¹ μM⁻¹), which may provide a competitive advantage over other macrophytes across a wide range of Pi concentrations.     

Effects of Bacillus thuringiensis toxin Cry1Ac and cytoplasmic polyhedrosis virus of Helicoverpa armigera (Hübner) (HaCPV) on cotton bollworm (Lepidoptera: Noctuidae)

In this study, interactions on the mortality and debilitating effects between Cry1Ac, a toxic protein produced by Bacillus thuringiensis (Berliner) and HaCPV (Chinese strain) on first and third instars larvae of Helicoverpa armigera were evaluated in laboratory. When first instar was exposed to combination of Bt cotton leaf discs containing HaCPV (6 × 10⁶, 1 × 10⁷, and 3 × 10⁷ PIB ml⁻¹) the effect on mortality was additive, when such instar larvae exposed to combination of Cry1Ac (0.9, 2.7, or 8.1 μg g⁻¹) and the same concentrations of HaCPV the effect on mortality was additive except for the combination of Cry1Ac (0.3 μg g⁻¹) and HaCPV concentrations that showed synergism. When third instars of H. armigera were infected using a suspension containing both HaCPV and Cry1Ac, most combinations of them showed additive effect except for the combination of Cry1Ac (0.3 μg g⁻¹) and HaCPV (3 × 10⁷ PIB ml⁻¹) that showed synergism. However, when they exposed to Bt cotton leaf discs and HaCPV the effect on mortality was synergism except combination of Bt cotton leaf discs and HaCPV (6 × 10⁶ PIB ml⁻¹) that showed additive. Most of the combinations are showed additive effect in the toxicity and in combinations of Cry1Ac at lowest and HaCPV at highest concentrations synergism is observed. Not only were larval growth and development delayed, but pupation and pupal weight also decreased when larvae were fed on artificial diet containing Cry1Ac and HaCPV or transgenic Bt cotton leaf discs specially in first instar.     

Phytofiltration of arsenic from simulated contaminated water using Hydrilla verticillata in field conditions

The present study investigated arsenic (As) removal efficiency of Hydrilla verticillata from simulated As-contaminated water in field conditions. Plants (100 g fresh weight) were grown in simulated contaminated water (total 8 L) containing 1500 μg L⁻¹ As [in the form of arsenate (AsV)] for 45 d and As accumulation and biochemical changes were analyzed at 15 d intervals. As accumulation in plants increased progressively approaching 388 μg g⁻¹ dw at 45 d. Considering the total dry biomass, total As removed was 8546 μg (i.e. 72% of total As supplied). Despite significant As accumulation, no toxic effects were observed in terms of the level of hydrogen peroxide and lipid peroxidation, which could be attributed to the enhanced level of thiol metabolites (cysteine, glutathione) and enzymatic antioxidants (guaiacol peroxidase, catalase, ascorbate peroxidase). The study demonstrates that Hydrilla plants can find application in As remediation in field conditions.     

Sorgoleone,a sorghum root exudate: Algicidal activity and acute toxicity to the ricefish Oryzias latipes

The discovery of natural and natural-based compounds has resulted in its application as an alternative to synthetic algicides to control harmful algae in aquatic systems. Of the many natural-product-based algicides, sorgoleone, a natural plant product from Sorghum bicolor root exudates has been investigated for its controlling effect on different algal species and its acute fish toxicity. Growth of the blue green algal species Microcystis aeruginosa Kützing was completely inhibited by the crude methanol extract of sorghum root at 20 μg mL⁻¹. The most noticeable inhibition was observed in the bioassay of n-hexane soluble extract, where 98% growth inhibition occurred in M. aeruginosa at the concentration of 1.25 μg mL⁻¹. Sorgoleone very effectively controlled blue green algae inhibiting 97% of M. aeruginosa at 0.5 μg mL⁻¹ and 99% of Anabaena affinis Lemmermann at 4 μg mL⁻¹. In contrast, inhibition of the green algae species Chlorella vulgaris Beijerinck and Scenedensmus spp. at 16 μg mL⁻¹ sorgoleone was 87 and 68%, respectively. There were no mortalities or adverse effects observed in any of the fish exposed to water control, solvent control, and a nominal concentration of 1 μg mL⁻¹ during the test period. The no observed effect concentration (NOEC) value was 1.5 μg mL⁻¹ for the tested fish (O. latipes). Sorgoleone can be considered as an effective and an ecologically and environmentally sustainable approach to controlling harmful algae.     

Enhanced 2,3-butanediol production by Klebsiella oxytoca using a two-stage agitation speed control strategy

Batch fermentative production of 2,3-butanediol by Klebsiella oxytoca was investigated using various oxygen supply methods though varying agitation speed. Based on the analysis of three kinetic parameters including specific cell growth rate (μ), specific glucose consumption rate (q_s) and specific 2,3-butanediol formation rate (q_p), a two-stage agitation speed control strategy, aimed at achieving high concentration, high yield and high productivity of 2,3-butanediol, was proposed. At the first 15 h, agitation speed was controlled at 300 rpm to obtain high μ for cell growth, subsequently agitation speed was controlled at 200 rpm to maintain high q_p for high 2,3-butanediol accumulation. Finally, the maximum concentration of 2,3-butanediol reached 95.5 g l⁻¹ with the yield of 0.478 g g⁻¹ and the productivity of 1.71 g l⁻¹ h⁻¹, which were 6.23%, 6.22% and 22.14% over the best results controlled by constant agitation speeds.     

Nitrogen nutrition of Canna indica: Effects of ammonium versus nitrate on growth, biomass allocation, photosynthesis, nitrate reductase activity and N uptake rates

The effects of inorganic nitrogen (N) source (NH₄⁺, NO₃⁻ or both) on growth, biomass allocation, photosynthesis, N uptake rate, nitrate reductase activity and mineral composition of Canna indica were studied in hydroponic culture. The relative growth rates (0.05-0.06 g g⁻¹ d⁻¹), biomass allocation and plant morphology of C. indica were indifferent to N nutrition. However, NH₄⁺ fed plants had higher concentrations of N in the tissues, lower concentrations of mineral cations and higher contents of chlorophylls in the leaves compared to NO₃⁻ fed plants suggesting a slight advantage of NH₄⁺ nutrition. The NO₃⁻ fed plants had lower light-saturated rates of photosynthesis (22.5 μmol m⁻² s⁻¹) than NH₄⁺ and NH₄⁺/NO₃⁻ fed plants (24.4-25.6 μmol m⁻² s⁻¹) when expressed per unit leaf area, but similar rates when expressed on a chlorophyll basis. Maximum uptake rates (V_max) of NO₃⁻ did not differ between treatments (24-35 μmol N g⁻¹ root DW h⁻¹), but V_max for NH₄⁺ was highest in NH₄⁺ fed plants (81 μmol N g⁻¹ root DW h⁻¹), intermediate in the NH₄NO₃ fed plants (52 μmol N g⁻¹ root DW h⁻¹), and lowest in the NO₃⁻ fed plants (28 μmol N g⁻¹ root DW h⁻¹). Nitrate reductase activity (NRA) was highest in leaves and was induced by NO₃⁻ in the culture solutions corresponding to the pattern seen in fast growing terrestrial species. Plants fed with only NO₃⁻ had high NRA (22 and 8 μmol NO₂⁻ g⁻¹ DW h⁻¹ in leaves and roots, respectively) whereas NRA in NH₄⁺ fed plants was close to zero. Plants supplied with both forms of N had intermediate NRA suggesting that C. indica takes up and assimilate NO₃⁻ in the presence of NH₄⁺. Our results show that C. indica is relatively indifferent to inorganic N source, which together with its high growth rate contributes to explain the occurrence of this species in flooded wetland soils as well as on terrestrial soils. Furthermore, it is concluded that C. indica is suitable for use in different types of constructed wetlands.     

Seasonal dynamics of allelopathically significant phenolic compounds in globally successful invader Conyza canadensis L. plants and associated sandy soil

The seasonal dynamics of total phenolics and phenolic acids in the stems of the global invader Conyza canadensis, from March (young plants in the form of rosettes) to September (fruit abscission and the beginning of plant decline), and in sandy soil were monitored monthly in non-native areas. The highest amount of total free phenolics was found in its tissues (31,000 μg g⁻¹) during the flowering and fruiting time (August). Bound phenolics peaked (up to 8443 μg g⁻¹) during shoot elongation and intensive plant growth (May–June) and in September. In the stems, bound phenolic acids (p-coumaric, ferulic, p-hydroxybenzoic, vanillic and syringic) have a maximum twice, in May and in August, with ferulic acid predominating (up to 951.6 μg g⁻¹). Free phenolic acids in the plant's tissue peaked in May (plant elongation). In the soil under C. canadensis, the amount of bound phenolics decreased between March and June, before increasing up to the full bloom phase of the plants (August). The amount of bound phenolic acids was several times greater than that of free ones, with maximum values in August. C. canadensis is a highly important source of phenolics in the ruderal phytocoenosis in new areas. In order to better explain the mechanisms of the spread and domination of invasive plants in non-native areas, in which allelopathy plays a decisive role, it is necessary to measure the production of allelochemicals in tissue and their accumulation in soil at the shortest possible intervals and link this with the phases of plant development.     

Structural characterization and protective effect against murine sepsis of fucogalactans from Agaricus bisporus and Lactarius rufus

Fucogalactans from edible Agaricus bisporus (RFP-Ab) and wild Lactarius rufus (RFP-Lr) mushrooms were obtained on aqueous extraction followed by purification. RFP-Ab had M_w 43.8 × 10⁴ g mol⁻¹ and RFP-Lr M_w 1.4 × 10⁴ g mol⁻¹. RFP-Lr had a (1 → 6)-linked α-d-Galp main-chain partially substituted at O-2 by nonreducing end-units of α-l-Fucp (29%). While RFP-Ab had a similar main chain, it was partially substituted at O-2 by nonreducing end-units of α-l-Fucp (2.8%) and β-d-Galp (14.5%), and partially methylated at HO-3. Both RFP-Lr and RFP-Ab were tested in mice against polymicrobial sepsis. Lethality rate, myeloperoxidase (MPO) activity and cytokine levels were determined. It was observed a reduction in late mortality rate by 62.5% and 50%, respectively, prevention of neutrophil accumulation in ileum and decreasing in TNF-α and IL-1β serum levels.     

Butyric acid fermentation in a fibrous bed bioreactor with immobilized Clostridium tyrobutyricum from cane molasses

Butyrate fermentation by immobilized Clostridium tyrobutyricum was successfully carried out in a fibrous bed bioreactor using cane molasses. Batch fermentations were conducted to investigate the influence of pH on the metabolism of the strain, and the results showed that the fermentation gave a highest butyrate production of 26.2 g l⁻¹ with yield of 0.47 g g⁻¹ and reactor productivity up to 4.13 g l⁻¹ h⁻¹ at pH 6.0. When repeated-batch fermentation was carried out, long-term operation with high butyrate yield, volumetric productivity was achieved. Several cane molasses pretreatment techniques were investigated, and it was found that sulfuric acid treatment gave better results regarding butyrate concentration (34.6 ± 0.8 g l⁻¹), yield (0.58 ± 0.01 g g⁻¹), and sugar utilization (90.8 ± 0.9%). Also, fed-batch fermentation from cane molasses pretreated with sulfuric acid was performed to further increase the concentration of butyrate up to 55.2 g l⁻¹.     

Ecophysiological responses of the mangrove Avicennia marina to trace metal contamination

Growth responses of Avicennia marina seedlings to contamination by different concentrations of two essential (Cu, Zn) and two non-essential (Pb, Hg) trace metals were studied under glasshouse conditions. We tested the hypothesis that soil retention and root ultrafiltration would exclude most of the trace metals, and that those that are absorbed and translocated to the shoots would interfere with plant performance and be excreted via leaf salt glands. One-month-old seedlings were subjected to Cu, Zn, Pb and Hg at concentrations of 0, 40, 80, 120 and 160 μg g⁻¹ sediment for 12 months in a randomized complete block design (n = 6). Photosynthesis was measured at the end of 12 months of trace metal exposure with a portable gas exchange system and chlorophyll fluorescence with a pulse-modulated fluorometer. After morphometric measurements, plants were harvested and analyzed for Cu, Zn, Pb and Hg by atomic absorption spectroscopy. Total dry biomass decreased with increasing trace metal concentration for all metals. In the 160 μg g⁻¹ Cu, Zn, Hg and Pb treatments, total biomass was significantly lower than the control value by 43%, 37%, 42% and 40%, respectively. Decreases in plant height and number of leaves followed trends similar to those for total biomass and ranged from 37% to 60%, compared to the controls. Decreases in chlorophyll content in the trace metal treatments ranged from 50% to 58% compared to the control. Carbon dioxide exchange, quantum yield of photosystem II (PSII), electron transport rate (ETR) through PSII and photosynthetic efficiency of PSII (F_v/F_m) were highest in the control treatment and decreased with increasing trace metal concentrations. Decreases in CO₂ exchange in the 160 μg g⁻¹ treatments for all trace metals ranged from 50% to 60%. Concentrations of all trace metals in plant organs increased with increasing metal concentrations and were higher in roots than in shoots, with concentrations of Cu and Zn being considerably higher than those of Hg and Pb. Qualitative elemental analyses and X-ray mapping of crystalline deposits over the glands at the leaf surfaces indicated that Cu and Zn were excreted from the salt glands, while Hg and Pb were absent, at least being below the limits of detection. These results demonstrate that growth processes are sensitive to trace metals and therefore can be considered as a cost of metal tolerance, but salt glands of this mangrove species do contribute eliminating at least part of physiologically essential trace metals if taken up in excess.     

Purification and characterization of two extracellular endochitinases from Massilia timonae

Two extracellular chitinases (designated as Chi-56 and Chi-64) produced by Massilia timonae were purified by ion-exchange chromatography, ammonium sulfate precipitation, and gel-filtration chromatography. The molecular mass of Chi-56 was 56 kDa as determined by both SDS-PAGE and gel-filtration chromatography. On the other hand, Chi-64 showed a molecular mass of 64 kDa by SDS-PAGE and 28 kDa by gel-filtration chromatography suggesting that its properties may be different from those of Chi-56. The optimum temperature, optimum pH, pI, K_m, and V_max of Chi-56 were 55 °C, pH 5.0, pH 8.5, 1.1 mg mL⁻¹, and 0.59 μmol μg⁻¹ h⁻¹, respectively. For Chi-64, these values were 60 °C, pH 5.0, pH 8.5, 1.3 mg mL⁻¹, and 1.36 μmol μg⁻¹ h⁻¹, respectively. Both enzymes were stimulated by Mn²⁺ and inhibited by Hg²⁺, and neither showed exochitinase activity. The N-terminal sequences of Chi-56 and Chi-64 were determined to be Q-T-P-T-Y-T-A-T-L and Q-A-D-F-P-A-P-A-E, respectively.     

Chemical profile of the North American native Myriophyllum sibiricum compared to the invasive M. spicatum

Myriophyllum spicatum L. is a nonindigenous invasive plant in North America that can displace the closely related native Myriophyllum sibiricum Komarov. We analyzed the chemical composition (including: C, N, P, polyphenols, lignin, nonpolar extractables, and sugars) of M. spicatum and M. sibiricum and determined how the chemistry of the two species varied by plant part with growing environment (lake versus tank), irradiance (full sun versus 50% shading), and season (July through September). M. spicatum had higher concentrations of carbon, polyphenols and lignin (C: 47%; polyphenols: 5.5%; lignin: 18%) than M. sibiricum (C: 42%; polyphenols: 3.7%; lignin: 9%) while M. sibiricum had a higher concentration of ash under all conditions (12% versus 8% for M. spicatum). Apical meristems of both species had the highest concentration of carbon, polyphenols, and tellimagrandin II, followed by leaves and stems. Tellimagrandin II was present in apical meristems of both M. spicatum (24.6 mg g⁻¹ dm) and M. sibiricum (11.1 mg g⁻¹ dm). Variation in irradiance from 490 (shade) to 940 (sun) μmol of photons m⁻² s⁻¹ had no effect on C, N, and polyphenol concentrations, suggesting that light levels above 490 μmol of photons m⁻² s⁻¹ do not alter chemical composition. The higher concentration of polyphenols and lignin in M. spicatum relative to M. sibiricum may provide advantages that facilitate invasion and displacement of native plants.     

Nitrogen nutrition of Salvinia natans: Effects of inorganic nitrogen form on growth,morphology, nitrate reductase activity and uptake kinetics of ammonium and nitrate

In this study we assessed the growth, morphological responses, and N uptake kinetics of Salvinia natans when supplied with nitrogen as NO₃⁻, NH₄⁺, or both at equimolar concentrations (500 μM). Plants supplied with only NO₃⁻ had lower growth rates (0.17 ± 0.01 g g⁻¹ d⁻¹), shorter roots, smaller leaves with less chlorophyll than plants supplied with NH₄⁺ alone or in combination with NO₃⁻ (RGR = 0.28 ± 0.01 g g⁻¹ d⁻¹). Ammonium was the preferred form of N taken up. The maximal rate of NH₄⁺ uptake (V_max) was 6–14 times higher than the maximal uptake rate of NO₃⁻ and the minimum concentration for uptake (C_min) was lower for NH₄⁺ than for NO₃⁻. Plants supplied with NO₃⁻ had elevated nitrate reductase activity (NRA) particularly in the roots showing that NO₃⁻ was primarily reduced in the roots, but NRA levels were generally low (<4 μmol NO₂⁻ g⁻¹ DW h⁻¹). Under natural growth conditions NH₄⁺ is probably the main N source for S. natans, but plants probably also exploit NO₃⁻ when NH₄⁺ concentrations are low. This is suggested based on the observation that the plants maintain high NRA in the roots at relatively high NH₄⁺ levels in the water, even though the uptake capacity for NO₃⁻ is reduced under these conditions.     

pH-control modes in a 5-L stirred-tank bioreactor for cell biomass and exopolysaccharide production by Tremella fuciformis spore

The effect of pH-control modes on cell growth and exopolysaccharide production by Tremella fuciformis was evaluated in a 5-L bioreactor. The results show that the maximal dry cell weight (DCW) and exopolysaccharide production were 23.57 and 4.48 g L⁻¹ in pH-stat fermentation, where the maximal specific growth rate (μ_max) and specific production rate of exopolysaccharide (P_P/X) were 1.03 and 0.24 d⁻¹, respectively; under pH-shift cultivation, the maximal DCW and exopolysaccharide production were 30.57 and 3.90 g L⁻¹, where the μ_max and P_P/X were 1.21 and 0.06 d⁻¹. Unlike batch fermentation, maximal DCW and exopolysaccharide production merely reached 15.04 and 2.0 g L⁻¹, where the μ_max and P_P/X were 0.86 and 0.05 d⁻¹, respectively. These results suggest that a pH-stat strategy is a more efficient way of performing the fermentation process to increase exopolysaccharide production. Furthermore, this research has also proved that the three-stage pH-control mode is effective for cell growth.     

Salinity increases the triterpenoid content of a salt secretor and a non-salt secretor mangrove

The present study describes the effect of salinity on the triterpenoid content of the salt secretor mangrove Avicennia marina and the non-secretor Rhizophora stylosa. Mangrove seedlings were grown for eight months in 0%, 0.5%, 1.5%, 2.0% and 3.0% salt concentration. The growth of both species was increased by salt with maximal stimulation at 1.5%, and this elevation appeared to be attenuated by increasing the salt concentration above 1.5%. The triterpenoid compositions of three types of chemical structures, lupane (lupeol, lupenone), oleanane (β-amyrin, taraxerol, germanicol), and ursane (α-amyrin), were studied. In addition, the phytosterol components campesterol, stigmasterol and β-sitosterol were analyzed. The total triterpenoid contents in the roots and leaves of A. marina for the 0% group were 87.0 and 66.2 μg g⁻¹, respectively, and increased significantly to 173.1 and 142.6 μg g⁻¹ with 3% salinity. The higher salinity also significantly increased the total concentration of phytosterols in the leaves and roots of this species. A similar increase in the concentration of both triterpenoids and phytosterols was observed in the roots and leaves of R. stylosa with increasing salt concentration. Thus, the triterpenoid concentration was increased by salinity in the roots and leaves of both A. marina and R. stylosa irrespective of their differences in salt management by salt excretion or by a non-excretion mechanism. Comparison of the triterpenoid concentration in four species of growing mangrove seedlings revealed a correlation between the total triterpenoid content and the salt tolerance based on the habitat zonation on Iriomote Island. A. marina thrives closest to sea and had the highest content of triterpenoids (173.1 μg g⁻¹ in 3% salt group). Therefore, it is likely that the triterpenoid content play an important role in mangrove plants for protection from salinity in both salt-secretors and non-secretors.     

Effects of Bacillus thuringiensis toxin Cry1Ac and Beauveria bassiana on Asiatic corn borer (Lepidoptera: Crambidae)

In this study, interactions between Cry1Ac, a toxic crystal protein produced by Bacillus thuringiensis (Berliner), and Beauveria bassiana on the mortality and survival of Ostrinia furnacalis was evaluated in the laboratory. The results showed that Cry1Ac is toxic to O. furnacalis. Not only were larval growth and development delayed, but pupation, pupal weight and adult emergency also decreased when larvae were fed on artificial diet containing purified Cry1Ac toxin. When third instars O. furnacalis were exposed to combination of B. bassiana (1.8 × 10⁵, 1.8 × 10⁶ or 1.8 × 10⁷ conidia ml⁻¹) and Cry1Ac, (0.2 or 0.8 μg g⁻¹), the effect on mortality was additive, however, the combinations of sublethal concentrations showed antagonism between Cry1Ac (3.2 or 13 μg g⁻¹) and B. bassiana (1.8 × 10⁵ or 1.8 × 10⁶ conidia ml⁻¹). When neonates were reared on sublethal concentrations of Cry1AC until the third instar, and survivors exposed B. bassiana conidial suspension, such treatments showed additive effect on mortality of O. furnacalis except for the combination of Cry1Ac (0.2 μg g⁻¹) and B. bassiana (1.8 × 10⁶ conidia ml⁻¹) that showed antagonism.     

Sulfated polysaccharides from Laminaria angustata: Structural features and in vitro antiviral activities

Sulfated polysaccharides potently inhibit the infectivity of herpes simplex virus (HSV) in cultured cells. In this study, we have analyzed sulfated xylogalactofucan and alginic acid containing fractions generated from Laminaria angustata, a marine alga. The xylogalactofucan that has apparent molecular mass of 56 ± 5 kDa and unusually low sulfate content contains, inter alia, 1,3-, 1,4- and 1,2-linked fucopyranosyl residues. The algin (molecular mass: 32 ± 5 kDa) contains gulo- (55.5%) and mannuronic (44.5%) acid residues. Introduction of sulfate groups enhanced the macromolecules capability to inhibit the infection of cells by HSV-1. The 50% inhibitory concentration (IC₅₀) values of these macromolecules against HSV-1 were in the range of 0.2-25 μg ml⁻¹ and they lacked cytotoxicity at concentrations up to 1000 μg ml⁻¹. The sulfate content appeared to be an important hallmark of anti-HSV-1 activity. Our results suggest the feasibility of inhibiting HSV attachment to cells by direct interaction of polysaccharides with viral particles.