异丙威·阿维菌素和丙溴磷·阿维菌素两种增效混配制剂对甜菜夜蛾的田间防治效果

24%异丙威·阿维菌素乳油对甜菜夜蛾的田间药效试验结果表明,该混剂药后3天、7天和10天校正防治效果优于异丙威和阿维菌素乳油两个单剂。该混剂用量为50 g/667 m²,药后3天、7天和10天的校正防效分别为82.38%、87.49%和88.90%;用量为37.5 g/667 m²,防效分别为78.21%、83.97%和85.24%。35%丙溴磷·阿维菌素乳油对甜菜夜蛾的田间药效试验结果表明,其对甜菜夜蛾速效性和持效性均佳。该混剂用量为50 g/667 m²,药后3天、7天和10天其校正防效分别为86.15%、91.37%和91.32%;用量为37.5 g/667 m²,防效分别为80.73%、87.40%和88.39%。     

The influence of hexavalent chromium salt on the population growth,cell morphology,and physiological parameters of the benthic microalga <Emphasis Type="Italic">Attheya ussurensis</Emphasis> Stonik,Orlova, Crawford, 2006 (BACILLARIOPHYTA) in culture

The presence of hexavalent chromium salt in culture medium negatively affected the growth dynamics and physiological parameters of the benthic microalga Attheya ussurensis. After 1 day of exposure to toxicant at concentrations of 2, 4, 7, and 10 mg/l, the cell counts were 10, 7.9, 5.6, and 4.3 × 10³ cells/ml, respectively (versus 13 × 10³ cells/ml in the control). A tendency towards a decrease in cell number remained until the end of the experiments; after 7 days of exposure the cell counts were 133, 102, 11, and 7.5 × 10³ cells/ml (versus 204 × 10³ cells/ml in the control). With increase in potassium bichromate concentration in the culture medium, there was an increase in the ratio of cell height to width and a change in the form of the cell to horseshoe shaped. The contents of chlorophyll a in microalgal cells after 1 day of exposure to 2, 4, 7, and 10 mg/l were 40, 37, 34, and 30 μg/l, respectively (45 μg/l in the control). After 7 days, at chromium salt concentrations of 2 and 4 mg/l, the chlorophyll a content was higher (670 and 647 μg/l) than in the control (605 μg/l); at 7 and 10 mg/l, it significantly decreased to 87 and 65 μg/l, respectively. The contents of carotinoids in microalgal cells after 7 days of exposure to 2 and 4 mg/l were comparable to the control values, while at 7 and 10 mg/l they decreased sharply. The amount of phaeophytin (as a percentage of total chlorophyll a content) increased with increasing potassium bichromate concentration.     

Heavy metal resistant <Emphasis Type="Italic">Distigma proteus</Emphasis> (Euglenophyta) isolated from industrial effluents and its possible role in bioremediation of contaminated wastewaters

Summary The alga, Distigma proteus, isolated from industrial wastewater showed tolerance against Cd²⁺ (8.0 μg/ml), Cr⁶⁺ (12 μg/ml), Pb²⁺ (15 μg/ml) and Cu²⁺ (10 μg/ml). The metal ions slowed down the growth of the organism after 4–5 days of exposure. The reduction in cell population was 90% for Cu²⁺, 84% for Cd²⁺, 71% for Cr⁶⁺, and 63% for Pb²⁺ after 8 days of metal stress. The order of resistance to heavy metal, in terms of reduction in the cellular population, was Cu²⁺ > Cd²⁺ > Cr⁶⁺ > Pb²⁺. Chromium- and cadmium-processing capabilities of the alga were worked out for its potential use as a bioremediator of wastewater. The reduction in the amount of Cr⁶⁺ after 2, 4, 6 and 8 days of algal culture containing 5.0 μg Cr⁶⁺ ml⁻¹ of culture medium was 77, 85, 92 and 97%, respectively. Distigma could also remove 48% Cd²⁺after 2 days, 68% after 4 days, 80% after 6 days and 90% after 8 days from the medium. The heavy metal uptake ability of Distigma can be exploited for metal detoxification and environmental clean-up operations.     

Bioassay method for assessing the virulence of Beauveria bassiana against tarnished plant bug, Lygus lineolaris (Hem., Miridae)

A standard bioassay method for assessing the pathogenicity of Beauveria bassiana (Balsamo) Vuillemin (GHA strain) against second instar tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hem., Miridae) was developed. Several types of inoculation methods, assay containers and incubation times were tested. Our goal was to minimize control mortality and maximize treatment mortality. Five inoculation methods (immersing broccoli florets or bean pods, spraying broccoli florets or bean pods, and immersing insects) and four types of plastic containers (114‐, 171‐, 228‐ and 455‐ml) were tested. Immersing insects directly in a fungal suspension was the most effective inoculation method, which resulted in a treatment mortality of 70–81.3% at a concentration of 1 × 10⁷ conidia/ml. The 114‐ml plastic container was the most suitable assay container when 10 tarnished plant bug nymphs were treated together, resulting in a control mortality of only 6% 12 days after treatment. Within the first 6 days after treatment, 71.1% of the insects were killed, compared with a total mortality of 81.3% after 12 days. Nymphs infected with the test fungus changed colour from green to black. Mycelial outgrowth and sporulation on the cadavers demonstrated that most nymphs died of fungal infection. A total of 61.1 and 80.5% of the cadavers showed signs of mycelial outgrowth 9 days after death among those that were surface sterilized and those that were not, respectively.     

Selection of entomopathogenic fungi for use in combination with sub-lethal doses of imidacloprid: perspectives for the control of the leaf-cutting ant <Emphasis Type="Italic">Atta sexdens</Emphasis><Emphasis Type="Italic">rubropilosa</Emphasis> Forel (Hymenoptera: Formicidae)

In the first part of this study, four isolates of the fungus Beauveria bassiana (Bals.) Vuillemin (LPP1, LPP2, CG05 and CG24) and one isolate of Metarhizium anisopliae (Metsch.) Sorokin (CG46) were tested against adult foragers of Atta sexdens rubropilosa. Ants were allowed to walk on filter paper discs, inside Petri dishes, previously impregnated with 1 ml of a conidia suspension (2 × 10⁷ conidia ml⁻¹), maintained at 80% RH and 26°C for 24 h and subsequently, transferred to sterile Petri dishes, maintained at 23°C, 80% RH, 24 h dark. The mean values of LT₅₀ for LPP2, LPP1, CG46, CG24 and CG05 were 3.5, 3.7, 3.8, 4.2 and 4.4 days, respectively. Control insects for all tests in this study showed less than 10% mortality. Experiments were carried out to test the toxicity of imidacloprid (IMI) to A. sexdens rubropilosa. Mortality was evaluated 10 days following a 24 h exposure to the insecticide. Percent mortality caused by 500, 200, 100 and 10 ppm IMI was 77.8, 56.7, 45.5 and 5.5 respectively. Insects treated with 10 ppm IMI were observed to have reduced locomotor activity 24 h after exposure to the insecticide. The LC₅₀ of IMI was 154.3 ppm. Subsequent tests were carried out to evaluate the combination of a sub-lethal dose of IMI (10 ppm) and infection by CG24 (1 × 10⁷ conidia ml⁻¹). Mortality due to fungal infection alone was 43.3%. Mortality of insects treated with IMI followed by exposure to the fungus was 64.3%. These results indicate that IMI significantly increases the susceptibility of ants to infection by B. bassiana CG24.     

Denitrification and N2O emission from urine-affected grassland soil

Denitrification and N₂O emission rates were measured following two applications of artificial urine (40 g urine-N m^–2) to a perennial rye-grass sward on sandy soil. To distinguish between N₂O emission from denitrification or nitrification, urine was also applied with a nitrification inhibitor (dicyandiamide, DCD). During a 14 day period following each application, the soil was frequently sampled, and incubated with and without acetylene to measure denitrification and N₂O emission rates, respectively.Urine application significantly increased denitrification and N₂O emission rates up to 14 days after application, with rates amounting to 0.9 and 0.6 g N m^–2 day^–1 (9 and 6 kg N ha^–1 day^–1), respectively. When DCD was added to the urine, N₂O emission rates were significantly lower from 3 to 7 days after urine application onwards. Denitrification was the main source of N₂O immediately following each urine application. 14 days after the first application, when soil water contents dropped to 15% (v/v) N₂O mainly derived from nitrification.Total denitrification losses during the 14 day periods were 7 g N m^–2, or 18% of the urine-N applied. Total N₂O emission losses were 6.5 and 3 g N m^–2, or 16% and 8% of the urine-N applied for the two periods. The minimum estimations of denitrification and N₂O emission losses from urine-affected soil were 45 to 55 kg N ha^–1 year^–1, and 20 to 50 kg N ha^–1 year^–1, respectively.     

Effect of Ca2+ Ions on the Viscometric Behavior of F-actin

Changes in the viscosity of the F-actin solutions which occur on addition of Ca²⁺ ions were investigated. The viscosity of F-actin decreased on addition of Ca²⁺ ions. The amount of Ca²⁺ ions needed to decrease the viscosity changed with pH of the solution, namely, 20~30 mm at pH 7, 15~20 mm at pH 6 and 5~10mm at pH 5.5. Other divalent cations had the same action on F-actin, but monovalent cations did not affect the F-actin viscosity even at the concentration as high as 1 m. Intrinsic viscosity of F-actin with and without Ca²⁺ions was 250 ±40 (ml/g) and 670 ±80 (ml/g), respectively. The cause of this viscosity change was discussed from the results of electron microscopic observation and light scattering measurements.     

Decomposition and mineralization of <Emphasis Type="Italic">Eichhornia crassipes</Emphasis> litter under aerobic conditions with and without bacteria

The water hyacinth (Eichhornia crassipes (Mart.) Solms.) plants in lakes and reservoirs have gained considerable attention in tropical and sub-tropical parts of the world due to its rapid growth. The amount of nutrients released from the dead plant materials is of particular interest. Thus, decomposition of water hyacinth plant parts under aerobic conditions was studied in the laboratory. Roots, petioles, and leaves of water hyacinth were enclosed separately in one litre polypropylene bottles which contained 500 ml of lake water. To study the influence of bacteria on the decomposition, antibiotics were added to half of the bottles. We observed that decomposition of leaves and petioles without antibiotics were relatively rapid through day 61, with almost 92.7 and 97.3% of the dry mass removed, respectively. Weight loss due to bacterial activities during 94 days decomposition was 22.6, 3.9, and 30.5% from leaf, petiole, and root litter. Decomposition of litter in lake water indicated that after 94 days 0.6, 0, and 0.6 g m^–2 of leaf, petiole, and root N was dissolved in leachate, while 23.1, 14.4, and 6.0 g m^–2 of leaf, petiole, and root N was either volatilized or remained as particulate organic N. Moreover, 0.2, 0, and 0.1 g m^–2 of leaf, petiole, and root P remained dissolved in the leachate, while 3.1, 3.4, and 1.1 g m^–2 of leaf, petiole, and root P was either precipitated or remained as particulate organic P. The carbon dynamics during the decomposition indicated that 7.4, 28.8, and 3.7 g m^–2 of leaf, petiole, and root C remained dissolved in the leachate after 94 days while 228.0, 197.6, and 107.4 g m^–2 of leaf, petiole, and root C was either diffused or remained as particulate organic C. These findings are useful for quantifying the nutrient cycles of very shallow lakes with water hyacinth under aerobic water environment. Further examination of the fate of the plant litter as it moves down in deep anaerobic water environment, is necessary to understand the leaching process better.     

A phase I biological study of azacitidine (VidazaTM) to determine the optimal dose to inhibit DNA methylation

This study aims to determine the optimal dosing and administration route for azacitidine to reduce global DNA methylation levels in the peripheral blood of patients with hematologic malignancies. Seventeen patients were enrolled into one of five dose level treatment groups (3 at 25mg/m², 4 at 50mg/m², 4 at 75mg/m², 3 at 100mg/m², and 3 at 150mg/m²) and received IV azacitidine at their respective dose on days 1-5 of cycle one. All patients received 75mg/m²/day IV on days 1-5 of cycle 2. Subcutaneous dosing of 75mg/m²/day on days 1-5 was used in cycle 3. Peripheral blood was collected on days 1, 3, and 5 of each cycle, and global DNA methylation was measured using bisulfite-PCR pyrosequencing of the DNA repetitive element LINE-1. 14 patients were evaluable for response with 2 CR, 2 PR, 7 SD and 3 PD reported. LINE-1 DNA methylation decreased by 1.37, 2.29, 4.81, 1.94 and 4.05% on day 5 for the 25mg/m², 50mg/m2, 75mg/m², 100mg/m² and 150mg/m² cycle one dose levels respectively. Mean decrease in LINE-1 DNA methylation was 3.7% with 75mg/m² IV and 3.4% by subcutaneous adminstration. The data indicates that 75mg/m² azacitidine given IV or SC effectively leads to global DNA methylation reduction by LINE-1 analysis.     

Production and regeneration of protoplasts from the mycorrhizal fungus Suillus granulatus

Experiments were performed with the mycorrhizal fungus Suillus granulatus to define the parameters for production and regeneration of protoplasts. Protoplasts were released at frequencies between 1 and 3×10⁷/ml from mycelium 3 to 7 days old. The best osmotic stabilizer for protoplast release was MgSO₄ (0.7 m). To optimize protoplast release and regeneration an enzyme (Novozym 234) concentration 1.7 mg/ml was chosen, with a digestion time of 1 to 2 h. Regenerated colonies formed mycorrhizae within 60 days after inoculation in Pinus caribaea var. hondurensis seedlings.     

Production and distribution of dry matter in maize following changes in plant population after flowering

Maize plants were grown singly in pots in a population of 3.7 plants m^-2, and 98 days after sowing (shortly after flowering) were arranged into three populations, 1.27 (W), 3.70 (M), and 6.15 (C) plants m^-2, respectively. The plants were harvested 131 days after sowing, about 4 wk before the normal time of maturity, because some plants at the closest spacing began dying. Increment of dry weight between days 98 and 131 was 373, 243, and 108 g/plant and grain dry weight at harvest was 218, 220 and 195 g/plant in populations W, M and C, respectively. Thus, dry weight of parts of the plant other than grain increased in population W, remained about the same in population M, and decreased in population C between days 98 and 131. Number of kernels per plant was c. 540 in all three populations. On day 98, immediately after rearrangement, leaf area index (L) was 2.0, 5.8 and 9.7 in populations W, M and C, respectively. By day 131 L had decreased to 6.7 in population C, but had hardly changed in the other two populations. Crop growth rate between days 98 and 131 was 101, 191 and 141 g m^-2 wk^-1, and grain dry wt per unit of land on day 131 was 277, 816 and 1196 g m^-2, in populations W, M and C, respectively.     

Antagonistic effect of enterocin CCM 4231 from Enterococcus faecium on “bryndza”, a traditional Slovak dairy product from sheep milk

“Bryndza” is a traditional Slovak dairy product (type of soft cheese) made from sheep cheese which was ripened for 14 days. Because its manufacture, transporting and/or storing represent conditions which facilitate contamination, the effect of enterocin CCM4231 in “bryndza” was investigated with the aim to reduce the contaminant agents. “Bryndza” was divided into equal portions (50 g). The experimental sample (ES) as well as the control sample one (C1) were inoculated with Listeria innocua Li1 strain. The other control samples C2 and C3 were without Li1 strain. C3 control was selected as a reference control. ES and C2 portions were treated with purified enterocin CCM4231 in a concentration of 6400 AU/ml. Before the experimental inoculation, “bryndza” was checked for the presence of contaminant agents. The experiment lasted 1 week and the samples were stored in the refrigerator at 4 °C. Sampling was performed on day 1, on day 4 and on day 7. The control samples C2 and C3 were checked only on day 1 and then after 1 week. The following contaminant agents were detected in “bryndza” before its experimental inoculation with L. innocua Li1 strain: Escherichia coli in the amount 10³ cfu/ml/g, Staphylococcus aureus (10² cfu/ml/g) and enterococci (10⁴ cfu/ml/g). In the control sample C2, the number of E. coli was reduced to 10² cfu/ml/g. Enterococci and staphylococci were totally eliminated there. Concerning C3 control, natural decrease of bacteria was found and/or their unchanged counts. The value of pH (5) was stable during the whole experiment. In the experimental sample inoculated with Li1 strain, its counts were decreased immediately after enterocin CCM4231 addition approximately by one order of magnitude. This inhibitory effect was also detectable on day 4 by the difference of one order of magnitude between ES and C1. On day 7, 10³ cfu/ml/g of Li1 strain were detected in both samples (ES, C1). The difference by one order of magnitude indicated, an inhibitory effect of enterocin CCM4231 in “bryndza”. However, bacteriocin activity was not determined by laboratory analyses.     

Initiation of humoral and cellular immune responses in patients with refractory Hodgkin's disease by treatment with an anti-CD16/CD30 bispecific antibody

Fifteen patients with refractory Hodgkin's disease were treated in a dose-escalation trial with the bispecific monoclonal antibody (bi-mAb) HRS-3/A9, which is directed against the Fcγ receptor III (CD16 antigen) and the Hodgkin's-associated CD30 antigen. Treatment consisted of four cycles of four bi-mAb infusions given over 1 h every 3–4 days at different dose levels ranging from 1 mg/m² to 64 mg/m². Measurable serum levels (above 0.1 μg/ml) of circulating bi-mAb could be detected in patients treated with doses above 4 mg/m², reaching peak levels of 9.5 μg/ml immediately after the end of antibody infusion on the highest dose level. Bi-mAb elimination corresponded to second-order kinetics with a terminal half-life time (t _1/2,β) of 28–32 h. Bi-mAb treatment induced the occurrence of human anti-(mouse Ig) antibodies (HAMA) in 6 out of 13 patients initially testing negative. All 6 patients not only developed anti-isotypic anti-(mouse Ig) but also anti-idiotypic and anti-anti-idiotypic antibodies. While no consistent changes of peripheral blood cell counts, or of any lymphocyte subpopulation including natural killer (NK) cells, has been observed, 4 out of 6 evaluable patients treated with doses of at least 4 mg/m² showed an increase of NK cell activity within 2 weeks after treatment, which lasted for a maximum of 12 weeks. Circulating amounts of soluble CD30 antigen could be detected in the serum of 6 patients. However, like the results and time courses of all the other immunological parameters evaluated, this was not predictive for treatment outcome. Received: 16 September 1999 / Accepted: 6 January 2000     

Characterization of glucoamylase from Lactobacillus amylovorus ATCC 33621

Summary An intracellular glucoamylase, purified from Lactobacillus amylovorus, reacted selectively with polysaccharides. Kinetic studies indicated low affinity for maltose and maltotriose (K_m 58 g/ml and 178 g/ml) and higher affinity for starch and dextrin (K_m 0.01 g/ml and 0.02 g/ml). Glucoamylase was inhibited almost 50% by 10 mM glucose. Cu²⁺ and Pb²⁺ inhibited glucoamylase at 1.0 mM but EDTA and other metal chelators had no effect on the enzyme activity. Acarbose and Tris inhibited the enzyme by 84% and 98%, respectively at 1 mM, while iodoacetate and p-chloromecuribenzoic acid inhibited activity by 98% and 78%, respectively at 10 mM. The purified enzyme was thermolabile at temperatures greater than 55°C and thus has potential for application in the brewing industry.     

Land use changes biomass and temporal patterns of insect cross-ecosystem flows

Emergent aquatic insects constitute an important food source for higher trophic levels, linking aquatic to terrestrial ecosystems. Little is known about how land use affects the biomass or composition of insect emergence. Previous studies are limited to individual time points or seasons, hampering understanding of annual biomass export patterns and detection of phenological changes. Over 1 year's primary emergence period, we continuously determined the biomass, abundance, and identity of >45,000 aquatic insects and recorded land-use-related environmental variables in 20 stream sites using a paired design with upstream forested sites and downstream agricultural sites. Total insect biomass and abundance were 2–7 mg day⁻¹ m⁻² and 7–36 ind day⁻¹ m⁻² higher in agricultural than forested sites. However, we found turnover of families between forested and agricultural sites, with more insects with shorter generation time in agriculture, indicating lower sensitivity to land-use-related stress because of higher recovery potential. Except for stoneflies, biomass and abundance of major orders were higher in agriculture, but their phenology differed. For different orders, emergence peaked 30 days earlier to 51 days later in agriculture than forest, whereas total abundance and biomass both peaked earlier in agriculture: 3–5 and 3–19 days, respectively. The most important land-use-related drivers were pesticide toxicity and electrical conductivity, which were differentially associated with different aquatic insect order abundances and biomass. Overall, we found that land use was related to changes in composition and phenology of aquatic insect emergence, which is likely to affect food-web dynamics in a cross-ecosystem context.     

Biocontrol of Fusarium and Verticillium Wilt of Tomato by Penicillium oxalicum under Greenhouse and Field Conditions

Treatments with conidia of Penicillium oxalicum produced in a solid‐state fermentation system were applied at similar densities (6 × 10⁶ spores/g seedbed substrate) to tomato seedbeds in water suspensions (T1: 5 days before sowing, or T2: 7 days before transplanting; 15 days after sowing), or in mixture with the production substrate (T3: 7 days before transplanting; 15 days after sowing). Treatments T2 and T3 significantly (P = 0.05) reduced fusarium wilt of tomato in both greenhouse (artificial inoculation) (33 and 28%, respectively) and field conditions (naturally infested soils) (51 and 72%, respectively), while treatment T1 was efficient only in greenhouse (52%). Verticillium wilt disease reduction was obtained with T3 in two field experiments (56 and 46%, respectively), while T1 and T2 reduced disease only in one field experiment (52% for both T1 and T2). Treatment with conidia of P. oxalicum plus fermentation substrate (T3) resulted in better establishment of a stable and effective population of P. oxalicum in seedbed soil and rhizosphere providing populations of approx. 10⁷ CFU/g soil before transplanting. Results indicate that it will be necessary to apply P. oxalicum at a rate of approx. 10⁶–10⁷ CFU/g in seedbed substrate and rhizosphere before transplanting for effective control of fusarium and verticillium wilt of tomato, and that formulation of P. oxalicum has a substantial influence on its efficacy.     

Longevity and quality of cut 'Master' carnation and 'Red Sandra' rose flowers as affected by red light

Cut flowering stems (45 cm long) of carnation (cv. Master) and rose (cv. Red Sandra) were placed in test tubes containing distilled water with or without commercial preservative (20 ml l^–1), under fluorescent tubes of 50 ± 10 mol m^–2 s^–1 Photosynthetic photon flux (PPF). A mixed radiation from fluorescent tubes with red light provided by light emitting diodes (LEDs) and monochromic red light of low 50 or high 90 ± 10 mol m^–2 s^–1 was also tested in the absence of preservative solution. Both red light with high PPF and the mixed radiation under low PPF extended the vase life of cut carnations, and flower freshness could be maintained for 10.9 days compared with a water/fluorescent light control. In cut rose, the treatment containing the preservative solution under fluorescent tubes alone and in red alone, regardless of light intensity, prolonged vase life for 4.6 and 4.2 days longer than the control, respectively. Treatment with red LEDs plus high PPF resulted in complete petal opening in carnation flowers.     

A developmental analysis of differences in the uptake of [123I]isopropyliodoamphetamine versus99mTc-pertechnetate by the choroid plexus and brain

The uptake of intravascular [¹²³I]isopropyliodoamphetamine (IMP) and^99mTc-pertechnetate into choroid plexus (CP) and brain (frontal cortex) was studied by an indicator fractionation method applied to immature, ketamine-anesthetized Sprague-Dawley rats (1.5, 2, and 3 wk). Assessment of the rate and extent of uptake of these indicators provides functional information (eg blood flow; transport) about various regions of the developing CNS. IMP uptake by lateral ventricle CP was 1.15 ml/g/min in 1.5-wk-old infant rats and gradually increased to 3.9 ml/g/min by adulthod (7–8 wk) (P<0.05); over the same postnatal period,^99mTc uptake went from 2.82 to 3.18 ml/g/min. IMP uptake by cortex was 0.39 and 0.99 ml/g/min in infants and adults, respectively (P<0.05); however,^99mTc uptake by cortex was only 0.07±0.01 ml/g/min at all ages, reflecting early development of blood-brain barrier (BBB) to pertechnetate. Overall, our findings indicated a progressive increase with age in the rate of uptake of IMP by CP and brain; and that^99mTc penetration into CP was relatively constant and substantially greater than into cortex at all developmental stages. Thus the nature of uptake of IMP, relative to^99mTc, was markedy different at the blood-cerebrospinal fluid barrier (i.e., CP) vs. the blood-brain barrier.     

Mixotrophic cultivation of <Emphasis Type="Italic">Platymonas subcordiformis</Emphasis>

The effects of glucose concentration and irradiance on mixotrophiccultivation of Platymonas subcordiformis were investigated in flaskcultures. The optimal glucose concentration was 24 g L^-1, andirradiance was 95 mol photon m^-2 s^-1. Based on theoptimization of culture conditions and a modified SK(IA) medium, themaximum biomass was 3.68 g L^-1 after 14 days, which was about6 times that in autotrophic culture, and the specific growth rate reached0.62 d^-1, twice that in autotrophic culture. Using the optimalconditions established in flasks, mixotrophic culture in a 5.0-Lphotobioreactor was achieved, and the yield after 8 days was 3.30 gL^-1.     

Influence of cis-dichlorodiamineplatinum on glioma cell morphology and cell cycle kinetics in tissue culture

Summary C6 glioma cells (CCL 107) were cultured for three days and then treated withcis-dichlorodiamineplatinum (cis-DDP) at doses of 0.2–10 µg/ml medium. Changes in DNA synthesis and DNA content, as well as morphology of cells and chromatin distribution, were examined from the first post-treatment day onwards. The number of cells labelled with [³H]thymidine, detected autoradiographically, decreased after treatment with 0.2–10 µg/ml by approximately one half on post-treatment day 1 and diminished further by the third day after treatment. The labelled cells were entirely absent only after treatment with 10µg/ml, 7 days post-treatment. Mitoses decreased from 1.4–0.6% by post-treatment day 1 and completely disappeared by day 3 (1 µg/ml). Feulgen cytophotometry and propidium iodide cytofluorimetry revealed accumulation of cells in the S-phase, especially the latter part (0.5 and 1.0 µg/ml, post-treatment day 1) and subsequently also in G2 phase (post-treatment day 3). Incomplete cyto- and karyokinesis in some cycling cells was indicated by an increased number of binucleate cells and nuclei of higher ploidy classes. Labelled cells with intermediate DNA values were, on average, labelled less intensively, as was revealed by simultaneous measurements of DNA content and [³H]thymidine incorporation. Some cells displayed reduction in grain density over heterochromatin clumps. This would be in agreement with the late S-phase block of DNA replication. After post-treatment day 3 the density of cells in cultures was substantially lower. This was due to slowed transversing through the cell cycle and cell death occurring after post-treatment day 1 with higher doses or after day 2 with lower doses (up to 1 µg/ml). The size of the nuclei of surviving cells enlarged initially (post-treatment day 1) and later (day 7) giant cells with long, branched fibres similar to those of reactive astrocytes occurred. Texture analysis of Feulgen-stained nuclei revealed that the chromatin of cells treated withcis-DDP became less evenly distributed. This might be due either to the direct influence ofcis-DDP on the DNA molecule, or mediated by changes in cytoskeleton and cAMP levels described earlier.