Effect of rearing density on thyroid and interrenal gland activity and plasma and hepatic metabolite levels in rainbow trout, Salmo gairdneri Richardson

There were significant inverse correlations between rearing density of rainbow trout, Salmo gairdneri Richardson, and final body weight, plasma L-thyroxine (T₄), trüodo-L-tryronine (T₃), cortisol and protein concentrations, plasma T₄/T₃ ratios and thyroid epithelial cell height. In addition, hepatosomatic indices and plasma free fatty acid concentrations were higher in fish reared at low (134 g 1⁻¹) density compared with groups reared at medium (210g1⁻¹) or high density (299g 1⁻¹), and the post-feeding (3.5-4h) elevation in plasma glucose and triglyceride levels evident in trout maintained at low rearing density was not found in those fish reared at higher densities. There were no significant effects of rearing density on hematocrit, carcass composition, hepatic glycogen and lipid levels and interregnal nucleus size.     

STIMULATORY EFFECTS OF SUBSTANCE P ON NEURITE EXTENSION AND CYCLIC AMP LEVELS IN CULTURED NEUROBLASTOMA CELLS

Abstract— Synthetic substance P initially increased cyclic AMP levels and subsequently induced neurite extension in cultured neuroblastoma N 18 cells. The magnitude of these effects depended on the concentration of fetal calf serum (FCS) in the culture medium, being more evident in the presence of a lower (0.1%) concentration of FCS.
In Eagle's medium containing 0.1% FCS, low concentrations of substance P (10⁻⁷-10⁻⁵ M) increased cyclic AMP levels and stimulated neurite extension.
In Eagle's medium containing 5%FCS, both substance P at concentrations of 10⁻⁵-10⁻³M and dibutyryl cyclic AMP at concentrations of 10⁻⁴-10⁻²M increased cyclic AMP levels and stimulated neurite extension. The activities of acetylcholinesterase, (Na⁺+ K⁺)-, HCO₃⁻ and Mg²⁺ -stimulated-ATPase were also increased. Cell growth was inhibited.
Substance P at concentrations of 10-⁷-10⁻⁵M also stimulated the adenylate cyclase activity of a particulate fraction of N 18 in a concentration-dependent manner.     

Callus formation from cotyledon protoplasts of Pinus oocarpa and Pinus patula

Protoplasts were isolated from cotyledons of 11-day-old seedlings of Pinus oocarpa and P. patula ssp. tecunumanii . The best enzyme combination was Cellulase R10 + Pectolyase Y-23, associated with bovine serum albumin. When cultured at a low density [1.25 × 10³ to 5 × 10³ protoplast (ml)⁻¹] in a liquid medium, the cells divided. The medium contained glutamine and casein hydrolysate as nitrogen sources, and glucose as osmoticum. Rate of division was increased by supplementing the medium with l -ornithine, putrescine and spermidine. However, the rate remained low, with an absolute division frequency of ca 1%. Dilution allowed colony proliferation and fragmentation, leading to the formation of numerous microcalli that could be transferred to various solid media for further growth.     

EFFECTS OF CADMIUM TOXICITY ON GROWTH AND ELEMENTAL COMPOSITION OF MARINE PHYTOPLANKTON

Some classes of marine phytoplankton are believed to be more tolerant of high concentrations of trace metals than others, but the results of experimental tests of this hypothesis are ambiguous. Eleven species of phytoplankton representing five classes were grown in Aquil medium containing Cd concentrations between 10⁻⁸ and 10⁻⁵ M ([Cd²⁺]= 10^−9.85 to 10^−6.84 M), and growth rates and intracellular concentrations of Cd, C, N, and S were measured. The mean Cd²⁺ concentration (pCd⁵⁰) that reduced the growth rate of each species to 50% of its maximum varied by 2.5 orders of magnitude, from 10^−6.23 for Emiliania huxleyi to 10^−8.79 for Synechococcus sp. Taxonomic trends in Cd resistance were not apparent in these data. Cadmium quotas (mol Cd·L⁻¹ cell volume) were lowest in species of Bacillariophyceae (ANOVA, P < 0.001), suggesting that they might regulate Cd transport differently than other taxa. Cellular S:C molar ratios increased in four of seven phytoplankton grown at high pCd (7.37–6.84) compared to low Cd ion concentrations (no added Cd), a result of increases in S·L⁻¹ cell volume. Nitrogen:carbon molar ratios were also higher in Cd-exposed phytoplankton, as changes in N and S were highly correlated ( r = 0.98, P < 0.0001). In two species that were examined, S:C ratios increased as a linear function of increasing Cd concentration. The results demonstrate large variability in Cd resistance among phytoplankton that is primarily a function of interspecific differences in Cd detoxification.     

Effect of oxygen tension, salinity, temperature and organic matter concentration on the growth and nitrifying activity of an estuarine strain of Nitrosomonas

Abstract The effects of O₂ tension, temperature, salt concentration and organic matter concentration on the growth and nitrifying activity of Nitrosomonas N₃ isolated from Tay Estuary sediments have been investigated. Chemostat-grown cultures were able to grow and nitrify at dissolved O₂ concentrations as low as 0.1 mg O₂· 1⁻¹ (cell population densities were 15% of those obtained in fully aerated cultures). This bacterium was sensitive to reduced temperatures as chemostat-grown cultures washed out at growth temperatures below 15°C, at dilution rates > 0.025 · h⁻¹. Batch-grown cultures of Nitrosomonas N₃ were used to study the effects of NaCl and complex organic matter concentration on nitrifying activity. Maximum rates of NH⁺₄ oxidation were recorded at NaCl concentrations of 1% w/v, whilst tryptone soya broth (TSB), nutrient broth (NB), yeast extract broth (YEB) and peptone were inhibitory at concentrations > 10 mg · 1⁻¹.     

The effect of dissolved oxygen and salinity on the toxicity of ammonia to smolts of salmon, Salmo salar L.

The survival of Atlantic salmon smolts on exposure to constant concentrations of ammonia has been measured under laboratory conditions. At concentrations of dissolved oxygen close to the air-saturation value, the 24-h LC50 of un-ionised ammonia is 0.15 mg NH₃1⁻¹ in fresh water (hardness 264 mg 1⁻¹ as CaCO₃) and 0.3 mg NH₃1⁻¹ in 30% sea water; at concentrations of dissolved oxygen of 3.5 mg 1⁻¹ in fresh water and 3.1 mg 1⁻¹ in 30% sea water, the 24-h LC50 is 0.09 mg NH₃ 1⁻¹ and 0.12 mg NH₃ 1⁻¹ respectively; for fish acclimated for 1 day to a concentration of ammonia close to the 24-h median for un-acclimated fish, the median is increased between 38 and 79%, depending on test conditions.     

MORPHOLOGICAL CHANGES OF CULTURED MYOCARDIAL CELLS DUE TO CHANGE IN EXTRACELLULAR CALCIUM ION CONCENTRATION

Increase in the extracellular Ca²⁺ concentration from low (≤ 10⁻⁷ M) to normal (10⁻³ M) caused morphological changes of cultured myocardial cells obtained from fetal mouse heart. The extracellular Na⁺ and K⁺ concentrations of the normal medium (10⁻³ M Ca²⁺) did not significantly affect the genesis of these morphological changes. Like Ca²⁺, Ba²⁺ and Sr²⁺, but not Mg²⁺, Co²⁺ or Ni²⁺, could induce morphological changes. Increase in the extracellular Ca²⁺ concentration from 10⁻⁸ M to 10⁻³M also caused excess uptake of ⁴⁵Ca²⁺ by cultured myocardial cells. B–16CW 1 cells, which did not show these morphological changes, did not take up excess ⁴⁵Ca²⁺ on this treatment. Treatments, such as addition of verapamil or incubation at pH 6.3, which reduced the genesis of morphological changes, reduced the rate of ⁴⁵Ca²⁺ uptake by myocardial cells. These facts show that the morphological changes of myocardial cells induced by increasing the extracellular Ca²⁺ concentration from low to normal are due to excess uptake of Ca²⁺ by the myocardial cells.
The morphological changes of cultured myocardial cells induced by increasing the extracellular Ca²⁺ concentration from low to normal were reversed on further incubation of the cells in medium with or without Ca²⁺.     

Biochemical characterisation of ketoconazole inhibitory action on Aspergillus fumigatus

Abstract The effect of ketoconazole on growth, sterol composition, in vitro sterol biosynthesis and P450-CO complex formation and its interaction with microsomal P450 was determined. On solid medium and in liquid medium ketoconazole inhibited Aspergillus fumigatus growth completely at 5 × 10⁻⁵ M and 50% of the growth at 1.3 × 10⁻⁵ M and 2.1 × 10⁻⁵ M respectively. A close relationship between accumulation of 14α-methyl sterols (eburicol, obtusifoliol and 14α-methyl fecosterol) and depletion of ergosterol with growth arrest was observed in ketoconazole treated cultures. The half inhibitory concentration for in vitro ergosterol biosynthesis and half saturating concentration for type II binding spectrum of ketoconazole were calculated as 73.8 ± 6.3 nM and 0.13 ± 0.04 μM respectively. CO displacement studies revealed inhibition of CO-P450 complex formation by ketoconazole.     

Effects of phenolic acids on ammonia oxidation by terrestrial autotrophic nitrifying microorganisms

Abstract It has been hypothesized that vegetation in certain ecosystems inhibits nitrification in soil by producing phenolic compounds that inhibit oxidation of ammonia by nitrifying microorganisms. This hypothesis is based largely on a report that very low concentrations (10⁻⁶ M–10⁻⁸ M) of several phenolic acids (notably ferulic acid) completely inhibited NO₂⁻ production in an aqueous suspension of soil treated with (NH₄)₂SO₄ and a nutrient solution suitable for growth of Nitrosomonas and other autotrophic nitrifying microorganisms. To evaluate this hypothesis, we determined the effects of three ohenolic acids (ferulic acid, caffeic acid, and p -coumaric on nitrite production by representatives of three genera of terrestrial autotrophic nitrifying microorganisms ( Nitrosospira, Nitrosomonas , or Nitrosolubos ) grown on a defined medium containing NH₄⁺. We found that nitrite production by the Nitrososspira was not inhibited by ferulic acid, caffeic acid, or p -coumaric acid at concentrations of 10⁻⁶ or 10⁻⁵ M and was only slightly inhibited when these acids were at a concentration of 10⁻⁴ M. We also found that ferulic acid did not markedly inhibit nitrite production by the three genera of nitrifying microorganisms studied, even when its concentration was as high as 10⁻³ M. These observations invalidate the hypothesis tested because the phenolic acids studied did not significantly retard ammonia oxidation by autotrophic microorganisms even when their concentration in cultures of these microorganisms greatly exceeded their concentrations in soils.     

Cultural conditions for production of glucoamylase from Lactobacillus amylovorus ATCC 33621

Lactobacillus amylovorus ATCC 33621 is an actively amylolytic bacterial strain which produces a cell-bound glucoamylase (EC 3.2.1.3). Conditions of growth and glucoamylase production were investigated using dextrose-free de Man-Rogosa-Sharpe (MRS) medium in a 1.5 I fermenter, with varying dextrin concentration (0.1–1.5% (w/v)), pH (4.5–6.5) and temperature (25–55°C). Cell extracts were prepared by subjecting cells to treatment with a French Pressure cell in order to release intracellular proteins. Glucoamylase activity was then assayed. The effects of pH (4.0–9.0), temperature (15–85°C) and substrate (dextrin and starch, 0–2% w/v) concentration on crude enzyme activity were investigated. Optimal growth was obtained in MRS medium containing 1% (w/v) dextrin, at pH 5.5 and 37°C. Glucoamylase production was maximal at the late logarithmic phase of growth, during 16–18 h. Crude enzyme had a pH optimum of 6.0 and temperature optimum of 60°C. With starch as the substrate, maximal activity was obtained at a concentration of 1.5% (w/v). The effects of ions and inhibitors on glucoamylase activity were also investigated. Enzyme activity was not significantly influenced by Ca²⁺ and EDTA at 1 mmol 1⁻¹ concentration; however Pb²⁺ and Co²⁺ were found to inhibit the activity at concentrations of 1 mmol 1⁻¹. The crude enzyme was found to be thermolabile when glucoamylase activity decreased after about 10 min exposure at 60°C. This property can be exploited in the brewing of low calorie beers where only mild pasteurization treatments are used to inactivate enzymes. The elimination of residual enzyme effect would prevent further maltodextrin degradation and sweetening during long-term storage, thus helping to stabilize the flavour of beer.     

Induction of anthocyanin synthesis in relation to embryogenesis in a carrot suspension culture: Correlation of metabolic differentiation with morphological differentiation

A system in which anthocyanin synthesis could be induced under a defined condition, was established in a carrot suspension culture. A cell suspension culture of carrot ( Daucus carota L. cv. Kurodagosun) was subcultured for more than a year in a medium containing 5 × 10⁻⁷ M 2,4-dichlorophenoxyacetic acid (2,4-D). At every subculture the cultures were sieved through nylon screens and the cells and cell clusters collected in the size range of 31–81 μm were transferred to a fresh medium. When the cells were transferred to a medium without auxin, synthesis of anthocyanin was induced. Zeatin promoted anthocyanin synthesis in a medium lacking auxin, with maximum yields of anthocyanin obtained at 10⁻⁷ to 10⁻⁸ M zeatin, 2,4-D at higher concentrations than 10⁻⁷ M inhibited anthocyanin synthesis completely. The sieved cells were fractionated by Ficoll density gradient centrifugation. Somatic embryos were formed in the fraction of higher density (>14% of Ficoll) in a medium containing 10⁻⁷ M zeatin but lacking auxin, while synthesis of anthocyanin was hardly observed. On the other hand, cells in the fraction of lower density (<12% of Ficoll) synthesized anthocyanin in the same medium, but formed few embryos. Forty to fifty percent of the total cells in this lighter cell fraction synthesized anthocyanin at a maximum. The similarity between anthocyanin synthesis and embryogenesis was observed in the time course as well as in the effects of growth regulators. The correlation between metabolic and morphological differentiation is discussed.     

Resistance to cadmium by pretreated rainbow trout alevins

A toxicity test with cadmium concentrations ranging from 0·1 to 100·0 mg Cd 1⁻¹ was used to assess the effect of cadmium pretreatment on rainbow trout ( Salmo gairdneri Richardson) alevins. The median period of survival for fish pretreated at 0·01 mg Cd 1⁻¹ was found to be increased at test concentrations up to 10mg Cd 1⁻¹ compared with alevins pretreated with dilution water. However, at concentrations above 10mg Cd 1⁻¹ pretreatment at 0·01 mg Cd 1⁻¹ reduced the median period of survival.     

Simultaneous phototrophic and chemotrophic growth in the purple sulfur bacterium Thiocapsa roseopersicina M1

Abstract The anoxygenic phototrophic purple sulfur bacterium Thiocapsa roseopersicina was grown in illuminated continuous cultures with thiosulfate as growth limiting substrate. Aeration resulted in completely colorless cells growing chemotrophically, whereafter the conditions were changed to a 23 h oxic/1 h anoxic regime. After 11 volume changes at a dilution rate of 0.031 h⁻¹ (35% of μ_max) a time dependent equilibrium was established. During the 23 h oxic periods bacteriochlorophyll a synthesis (BChl a ) was not observed, whereas during the 1 h anoxic periods synthesis was maximal (i.e. 1.1 μg (mg protein)⁻¹ h⁻¹). As a result the BChl a concentration gradually increased from zero to an average value over 24 h of 1.9 μg (mg protein)⁻¹. Concomitantly, the protein concentration increased from 13.9 mg 1⁻¹ during continuous oxic conditions to 28.8 mg 1⁻¹. For comparison, the protein concentration during fully phototrophic growth at an identical thiosulfate concentration in the inflowing medium was 53.7 mg 1⁻¹. The specific respiration rate was 8 μmol O₂ (mg protein)⁻¹ h⁻¹ during full chemotrophic growth and gradually decreased to 3.5 μmol O₂ (mg protein)⁻¹ h⁻¹ after 11 volume changes at the regime employed. These data show that T. rosepersicina is able to simultaneously utilize light and aerobic respiration of thiosulfate as sources of energy. The ecological relevance of the data is discussed.     

Effect of high-temperature, short-time (HTST) pasteurization on milk containing low numbers of Mycobacterium paratuberculosis

The efficacy of high-temperature, short-time (HTST) pasteurization (72 °C/15 s) when low numbers (≤ 10³ cfu ml ⁻¹ ) of Mycobacterium paratuberculosis are present in milk was investigated. Raw cows' milk spiked with Myco. paratuberculosis (10³ cfu ml⁻¹, 10² cfu ml⁻¹, 10 cfu ml⁻¹, and 10 cfu 50 ml⁻¹) was subjected to HTST pasteurization using laboratory pasteurizing units. Ten bovine strains of Myco. paratuberculosis were tested in triplicate. Culture in BACTEC Middlebrook 12B radiometric medium detected acid-fast survivors in 14·8% and 10% of HTST-pasteurized milk samples at the 10³ and 10² cfu ml⁻¹ inoculum levels, respectively, whereas conventional culture on Herrold's egg yolk medium containing mycobactin J detected acid-fast survivors in only 3·7% and 6·7% of the same milk samples. IS900-based PCR confirmed that these acid-fast survivors were Myco. paratuberculosis . No viable Myco. paratuberculosis were isolated from HTST-pasteurized milk initially containing either 10 cfu ml⁻¹ or 10 cfu 50 ml⁻¹.     

The effects of 3-hydroxybutyrate and glucose on human T cell responses to Candida albicans

Abstract Diabetic patients are particularly susceptible to mucocutaneous candidosis. T lymphocytes are central to the induction of antigen-specific immune responses and may be sensitive to the biochemical abnormalities associated with poorly controlled diabetes; namely, hyperglycaemia and/or ketonemia. To examine this we have studied the effect of varying concentrations of glucose and 3-hydroxybutyrate (3-HB) in cultures of human T cells stimulated with Candida albicans antigen. Proliferation of T cells from six type 1 diabetic and six non-diabetic control subjects was significantly inhibited (both P <0.05) in glucose-free medium, and at a glucose concentration of 80 mmol 1⁻¹ as compared with cultures containing glucose at physiological concentration (5 mmol 1⁻¹). 16 and 32 mmol 1⁻¹ 3-HB also inhibited T cell proliferation in the presence of 5 mmol 1⁻¹ glucose ( P <0.05). The effect of glucose and 3-HB were not additive and the inhibition was not due to cell death. 32 mmol 1⁻¹ 3-HB had less effect when present solely during antigen pulsing than during subsequent lymphocyte stimulation, and was effective even when added after 72 h of a six day culture. This suggests that ketosis affects T cell proliferation more than antigen processing and presentation. We conclude that human antigen-specific T cell proliferation is inhibited in vitro only by concentrations of 3-HB encountered in moderately severe diabetic ketoacidosis, and by glucose concentrations found in severe hyperosmolar non-ketotic coma. The impairment of T cell function under such extreme conditions could be implicated in the close association of diabetic ketoacidosis with deep fungal infections, particularly invasive mucormycosis.     

Efficacy of certain disinfectants against infectious pancreatic necrosis virus

The virucidal properties of iodophor, chlorine (sodium hypochlorite), formalin, thimerosal (organic mercurial compound), malachite green, and acriflavine were tested on infectious pancreatic necrosis virus (IPNV). Iodine and chlorine showed good activity, but efficacy depended on the concentration of virus, the presence of organic matter (calf serum), and water _pH. Water hardness (0-300 mg 1⁻¹ as CaCO₃) did not affect virucidal activity. In a 5 min exposure, 4 mg 1⁻¹ available iodine inactivated 10^3.9 TCID₅₀ m1⁻¹ IPNV but 16 mg 1⁻¹ iodine were needed for inactivation of 10^6.3TCID₅₀m1⁻¹. The addition of 0-5% calf serum significantly reduced the iodine concentration and the virucidal activity. In comparison, 4 mg 1⁻¹ chlorine were needed to inactivate 10⁴⁶ TCID₅₀ m1⁻¹ IPNV in 5 min. However, the addition of 0-07 % serum greatly reduced the chlorine concentration and extended the virucidal contact time to 30 min or more. IPNV at 10^6.3 TCID₆₀ m1⁻¹ was not inactivated by exposures for 60 min to 0-2% formalin, 10 min to 0-2% thimerosal, 60 min to 5 mg 1⁻¹ malachite green, or 20 min to 500 mg 1⁻¹ acriflavine. However, acriflavine at 0-5 mg 1⁻¹ in cell culture media prevented the development of cytopathology caused by IPNV and may be useful in the treatment of the disease.     

Mechanism of phosphorus-induced zinc deficiency in cotton. III. Changes in physiological availability of zinc in plants Is mail

The effect of varied supply of P (2.5× 10⁻⁵ to 6× 10⁻⁴ M) and Zn (0 to 10⁻⁶ M) on uptake and concentrations of P and Zn was studied in cotton ( Gossypium hirsutum L. cv. Deltapine 15/21) grown in nutrient solution under controlled environmental conditions. At a given Zn supply, increasing levels of P had no significant effect on the concentrations of total Zn in plants. However, increasing levels of P induced or enhanced visual Zn deficiency symptoms when the Zn concentration in the nutrient solution was low. The concentrations of water-soluble Zn in roots and shoots constituted 60% of the total Zn concentrations for plants grown with low P and 30% for plants grown with high P. The concentration of water-soluble Zn in leaves, but not total Zn, was closely correlated with visual Zn deficiency symptoms, levels of chlorophyll, super oxide dismutase and membrane permeability. The critical deficiency concentration of water-soluble Zn in cotton leaves was in the range of 6 to 7 μg (g dry weight)⁻¹ or about 1.0 μg (g fresh weight)⁻¹. The results show that high P concentrations in plant tissue decrease the physiological availability of Zn. Water-soluble Zn in the tissue appears to be a suitable indicator for Zn nutritional status in general and phosphorus-induced Zn deficiency in particular. Also in field-grown orange trees (Citrus sinensis) visual Zn deficiency symptoms in leaves were closely related to the concentration of water-soluble Zn.     

Molybdenum-dependent degradation of nicotinic acid by Bacillus sp. DSM 2923

Abstract Growth of Bacillus sp. DSM 2923 on nicotinic acid in mineral medium was dependent on the concentration of sodium molybdate added. Addition of increasing amounts of tungstate to the medium resulted in an inhibition of growth on nicotinic acid or 6-hydroxynicotinic acid as sole source of carbon and energy. Chlorate-resistant mutants were isolated which were not able to degrade nicotinic acid and 6-hydroxynicotinic acid nor to reduce nitrate. Additionally, enzyme activities of nicotinic acid dehydrogenase and 6-hydroxynicotinic acid dehydrogenase increased with increasing concentrations of molybdate (10⁻⁸ to 10⁻⁶ M) added to the medium, and decreased with increasing amounts of tungstate (10⁻⁶ to 10⁻⁵ M) in the medium.     

Some effects of low pH and calcium on the growth and tissue mineral content of yearling brown trout, Salmo trutta

Yearling brown trout, Salmo trutta , were exposed to low mineral content water (nominal concentrations of 20μmol 1⁻¹ magnesium, 7.7 μmol 1⁻¹ potassium, 44 μmol 1⁻¹ sodium) over a pH range of 4.0–5.2 with ambient calcium concentrations of 2.5–60 μmol 1⁻¹. All fish died at pH 4.0 and 4.2 irrespective of ambient calcium concentration and also at pH 4.4 with only 2–3 μmol 1 ⁻¹ calcium (that is calcium-free water except for that leached from the diet or excreted by the fish). Good growth rates were obtained over the remaining treatments which extended down to pH 4.4 with as little as 7 μmol 1⁻¹ calcium. When starved, weight loss was inversely correlated with pH. Effects on plasma chloride, percentage dry weight and calcium, potassium sodium, and phosphorus contents of skin, muscle and bone tissue were also investigated. These demonstrated pH effects on mineral metabolism in starved fish, but no effects were detected in fed fish.     

Photoautotrophic growth in suspension culture of cells from the moss, Barbula unguiculata

Chlorophyllous cells in suspension culture from the moss, Barbula unguculata Hedw., grown under photoheterotrophic conditions were transferred to photoautotrophic conditions. The cells started to grow photoautotrophically without selection. Maximum growth was observed under irradiances of more than 5 W m² and in an atmosphere enriched with 1% (v/v) CO₂. Under optimum growth conditions, dry weight and chlorophyll content in the culture had increased 20-fold after 20 days of cell growth. High concentration of chlorophyll [10–20 μg (mg dry weight)⁻¹] and high photosynthetic actively [30–70 μmol O₂ evolved (mg chlorophyll)⁻¹ h⁻¹] were observed throughout the culture period. In sugar-free culture medium, cell growth did not occur in the dark or in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) under light, although cell growth was observed in glucose-containing medium under those conditions. When cells that were grown photoautotrophically for one year were transferred to glucose-containing medium under ordinary air, they started to grow heterotrophically both in the light and in the dark.