Effects of temperature, CO2/O2 concentrations and light intensity on cellular multiplication of microalgae, Euglena gracilis.

Microalgae culture is likely to play an important role in aquatic food production modules in bioregenerative systems for producing feeds for fish, converting CO2 to O2 and remedying water quality as well as aquatic higher plants. In the present study, the effects of culture conditions on the cellular multiplication of microalgae, Euglena gracilis, was investigated as a fundamental study to determine the optimum culture conditions for microalgae production in aquatic food production modules including both microalgae culture and fish culture systems. E. gracilis was cultured under conditions with five levels of temperatures (25-33 degrees C), three levels of CO2 concentrations (2-6%), five levels of O2 concentrations (10-30%), and six levels of photosynthetic photon flux (20-200 micromoles m-2 s-1). The number of Euglena cells in a certain volume of solution was monitored with a microscope under each environmental condition. The multiplication rate of the cells was highest at temperatures of 27-31 degrees C, CO2 concentration of 4%, O2 concentration of 20% and photosynthetic photon flux of about 100 micromoles m-2 s-1. The results demonstrate that E. gracilis could efficiently produce biomass and convert CO2 to O2 under relatively low light intensities in aquatic food production modules.

A PLCdelta1-binding protein, p122RhoGAP, is localized in focal adhesions.

We have investigated the cellular distribution of p122RhoGAP, a GTPase-activating protein of Rho small GTPase and an activator of phospholipase C-delta(1). Immunofluorescence studies demonstrated that endogenous p122 is localized at the tips of actin stress fibres and co-localizes with vinculin in normal rat kidney cells. In immunoprecipitation studies, p122 co-precipitated with vinculin, indicating that p122 is localized at the sites of focal adhesion. We have also shown that the N-terminal half of p122 is responsible for this localization. It is conceivable, therefore, that p122 is involved in the reorganization of the actin cytoskeleton and focal adhesions that regulate cell-substratum adhesion and cell migration.

Effects of air velocity on photosynthesis of plant canopies under elevated CO2 levels in a plant culture system.

To obtain basic data for adequate air circulation for promoting plant growth in closed plant production modules in bioregenerative life support systems in space, effects of air velocities ranging from 0.1 to 0.8 m s-1 on photosynthesis in tomato seedlings canopies were investigated under atmospheric CO2 concentrations of 0.4 and 0.8 mmol mol-1. The canopy of tomato seedlings on a plug tray (0.4 x 0.4 m2) was set in a wind-tunnel-type chamber (0.6 x 0.4 x 0.3 m3) installed in a semi-closed-type assimilation chamber (0.9 x 0.5 x 0.4 m3). The net photosynthetic rate in the plant canopy was determined with the differences in CO2 concentrations between the inlet and outlet of the assimilation chamber multiplied by the volumetric air exchange rate of the chamber. Photosynthetic photon flux (PPF) on the plant canopy was kept at 0.25 mmol m-2 s-1, air temperature at 23 degrees C and relative humidity at 55%. The leaf area indices (LAIs) of the plant canopies were 0.6-2.5 and plant heights were 0.05-0.2 m. The net photosynthetic rate of the plant canopy increased with increasing air velocities inside plant canopies and saturated at 0.2 m s-1. The net photosynthetic rate at the air velocity of 0.4 m s-1 was 1.3 times that at 0.1 m s-1 under CO2 concentrations of 0.4 and 0.8 mmol mol-1. The net photosynthetic rate under CO2 concentrations of 0.8 mmol mol-1 was 1.2 times that under 0.4 mmol mol-1 at the air velocity ranging from 0.1 to 0.8 m s-1. The results confirmed the importance of controlling air movement for enhancing the canopy photosynthesis under an elevated CO2 level as well as under a normal CO2 level in the closed plant production modules.

The effect of gravity on surface temperatures of plant leaves.

A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 degrees C, a relative humidity of 18% and an irradiance of 260 W m-2. Mean leaf temperatures increased by 0.9-1.0 degrees C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 degrees C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 degrees C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s-1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection.

Effects of air current speed on gas exchange in plant leaves and plant canopies.

To obtain basic data on adequate air circulation to enhance plant growth in a closed plant culture system in a controlled ecological life support system (CELSS), an investigation was made of the effects of the air current speed ranging from 0.01 to 1.0 m s-1 on photosynthesis and transpiration in sweetpotato leaves and photosynthesis in tomato seedlings canopies. The gas exchange rates in leaves and canopies were determined by using a chamber method with an infrared gas analyzer. The net photosynthetic rate and the transpiration rate increased significantly as the air current speeds increased from 0.01 to 0.2 m s-1. The transpiration rate increased gradually at air current speeds ranging from 0.2 to 1.0 m s-1 while the net photosynthetic rate was almost constant at air current speeds ranging from 0.5 to 1.0 m s-1. The increase in the net photosynthetic and transpiration rates were strongly dependent on decreased boundary-layer resistances against gas diffusion. The net photosynthetic rate of the plant canopy was doubled by an increased air current speed from 0.1 to 1.0 m s-1 above the plant canopy. The results demonstrate the importance of air movement around plants for enhancing the gas exchange in the leaf, especially in plant canopies in the CELSS.

Accumulation of silver in the liver of three species of pinnipeds.

Silver in the three species of pinnipeds [northern fur seal (Callorhinus ursinus), Steller sea lion (Eumetopias jubatus), and harbor seal (Phoca vitulina)] caught in the North Pacific Ocean were analyzed using inductively coupled plasma-mass spectrometry, in order to understand accumulation and distribution of silver in pinnipeds. In northern fur seals, relatively high concentrations of silver were observed in the liver and body hair. Some 70% of the silver burden was concentrated in the liver. Hepatic silver concentrations were significantly correlated to age in northern fur seals (r = 0.766, P < 0.001, n = 49) and Steller sea lions (r = 0.496, P < 0.01, n = 28). Levels of silver concentrations per wet weight (microgram g-1) in the three pinnipeds ranged from 0.04 to 0.55 for northern fur seals, from 0.1 to 1.04 for Steller sea lions and from 0.03 to 0.83 for harbor seals. Silver concentrations in liver for all pinnipeds were significantly correlated with mercury, and selenium (P < 0.001). Molar ratios between silver to selenium approximated 1:180 in northern fur seals, 1:120 in Steller sea lions, and 1:60 in harbor seals. The silver-mercury molar ratios were approximately 1:170 in northern fur seals, and 1:80 both in the other species. Increase in silver accumulation in the liver was caused by the retention in nuclei and mitochondria fraction together with mercury and selenium in the cells of northern fur seals.

The effect of gravity on surface temperature and net photosynthetic rate of plant leaves.

To clarify the effects of gravity on heat/gas exchange between plant leaves and the ambient air, the leaf temperatures and net photosynthetic rates of plant leaves were evaluated at 0.01, 1.0, 1.5 and 2.0 G of 20 seconds each during a parabolic airplane flight. Thermal images of leaves were captured using infrared thermography at an air temperature of 26 degrees C, a relative humidity of 15% and an irradiance of 260 W m-2. The net photosynthetic rates were determined by using a chamber method with an infrared gas analyzer at an air temperature of 20 degrees C, a relative humidity of 50% and a photosynthetic photon flux of 0.5 mmol m-2 s-1. The mean leaf temperature increased by 1 degree C and the net photosynthetic rate decreased by 13% with decreasing gravity levels from 1.0 to 0.01 G. The leaf temperature decreased by 0.5 degree C and the net photosynthetic rate increased by 7% with increasing gravity levels from 1.0 to 2.0 G. Heat/gas exchanges between leaves and the ambient air were more retarded at lower gravity levels. A restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air.

Vanadium accumulation in pinnipeds.

Vanadium in four species of pinnipeds (northern fur seals [Callorhinus ursinus], Steller sea lions [Eumetopias jubatus], harbor seals [Phoca vitulina], and ribbon seals [Phoca fasciata]) caught in the Northern Pacific was analyzed using ICP-MS to understand its accumulation and distribution. In northern fur seals, relatively high concentrations of vanadium were observed in the liver, hair, and bone. Ninety percent of the vanadium burden in the body was concentrated in these three tissues, which comprise <20% of total body weight. Hepatic vanadium concentrations in the four pinniped species were significantly correlated to age, although the levels varied with species. An increase in vanadium accumulation in the liver of northern fur seals was caused by an increase of retention in nuclei and mitochondria fraction in the cells. Vanadium concentrations in liver were significantly correlated with mercury, silver, and selenium concentrations in northern fur seals, Steller sea lions, and harbor seals.

The effects of time and intensity of supplemental blue lighting during morning twilight on growth and physiological performance of cucumber seedlings.

Cucumbers (Cucumis sativus L. cv. Naoyosi) were grown hydroponically at air temperatures of 28/24 degrees C (D/N) and photosynthetic photon flux (PPF) of 300 micromoles m-2 s-1, in a walk-in type growth cabinet equipped with 3-band fluorescent lamps. Plants were subjected to supplemental blue lighting applied daily just before the 14-h photoperiod (morning twilight) under PPFs of 0, 10, 30, 100, and 200 micromoles m-2 s-1. Treatment periods were 0, 5, 30, or 120 min. Growth and morphological parameters were measured after 12 and 14 days of treatment. On the 13th day of treatment, the stomatal conductance (gs), transpiration rate (Tr), and net photosynthetic rate (Pn) were measured under 3-band fluorescent lamps at a PPF of 200 micromoles m-2 s-1. After 17-19 days of treatment, changes in Pn effected by supplemental blue light were measured continuously for 30 min. Treatment with 5 min of blue lighting promoted more growth than treatment for 30 or 120 min. Similarly, gs, Tr, and Pn were the greatest in plants grown with supplemental blue light of 30 micromoles m-2 s-1 and 100 micromoles m-2 s-1 PPF for 5 min. Pn in plants grown under blue light of 30 micromoles m-2 s-1 for 5 min increased by 60% compared with that of control plants. Pn rose and was maintained at a higher level with 5-min blue lighting treatment. Supplemental lighting with blue light in the morning twilight is considered to be effective for seedling growth, and can be utilized for bionursery facilities to increase efficiency of plant production.

Effect of wind velocity on ethylene release from lettuce plants.

Effect of wind velocity on ethylene release rate of intact lettuce plant was investigated. Lettuce plants were grown at wind velocities of 0.1, 0.4, 0.8, and 1.4 m s-1 for 25 to 33 days and then used for ethylene measurement. When ethylene release rate of the plants grown at a wind velocity of 0.1m s-1 was measured at wind velocities of 0.2, 0.6 and 1.0m s-1 the rate was not affected by wind velocity. This result indicates that ethylene diffusion from lettuce leaf to atmosphere is not affected by boundary layer conditions. When ethylene release rate of the plants grown at wind velocities of 0.1, 0.4, 0.8 and 1.4 m s-1 was measured at the same wind velocity as growing conditions, the rate was scarcely increased by high velocity of wind. A strong wind (4.0 m s-1), which induced wounding damage in small areas of the leaves, had no measurable effect on a ethylene release of the whole plant.

Rates of ethylene release, photosynthesis and transpiration of rice measured in closed-type chamber.

To obtain the basic data of gas exchange of rice (Oryza sativa L. cv. Nipponbare), rates of ethylene release, photosynthesis and transpiration of the rice plant were measured by using a closed-type chamber. Each rate increased until the heading stage and thereafter decreased. Ethylene release rate (E) gradually increased with day after seeding and rates of photosynthesis (P) and transpiration (T) did exponentially. At the heading stage, E, P and T were maximum and had values of about 2.0 mmol plant-1 h-1, 3.0 mmol plant-1 h-1 and 0.60 mol plant-1 h-1, respectively. E in the light period was 1.5-3 times as much as that in the dark period, whereas T in the light period was 5-6 times as much as that in the dark period. E of rice per plant was lower than those of lettuce and Brassica genera which were reported previously. Especially, the rate of rice was about one-tenth that of lettuce. However, when ethylene release rates were estimated on a growth area basis, the rate of rice was about half that of lettuce, and was more than those of Brassica genera.

Measurements of trace contaminants in closed-type plant cultivation chambers.

Trace contaminants generated in closed facilities can cause abnormal plant growth. We present measurement data of trace contaminants released from soils, plants, and construction materials. We mainly used two closed chambers, a Closed-type Plant and Mushroom Cultivation Chamber (PMCC) and Closed-type Plant Cultivation Equipment (CPCE). Although trace gas budgets from soils obtained in this experiment are only one example, the results indicate that the budgets of trace gases, as well as CO2 and O2, change greatly with the degree of soil maturation and are dependent on the kind of substances in the soil. Both in the PMCC and in the CPCE, trace gases such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), toluene and xylene were detected. These gases seemed to be released from various materials used in the construction of these chambers. The degree of increase in these trace gas levels was dependent on the relationship between chamber capacity and plant quantity. Results of trace gas measurement in the PMCC, in which lettuce and shiitake mushroom were cultivated, showed that ethylene was released both from lettuce and from the mushroom culture bed. The release rates were about 90 ng bed-1 h-1 for the shiitake mushroom culture bed (volume is 1700 cm3) and 4.1 approximately 17.3 ng dm-2 h-1 (leaf area basis) for lettuce. Higher ethylene release rates per plant and per unit leaf area were observed in mature plants than in young plants.

Performance of a centrifugal phytotron.

It is possible to cultivate plants under an artificial gravity field generated by a centrifugal device in space. In order to determine an optimal magnitude of gravity, there is a need to investigate the relationship between plant and growth and gravity, including not only reduced gravity but also gravity greater than 1G. A prototype centrifugal phytotron was designed and fabricated in order to investigate the relationship between plant growth and increased gravity. This device enables us to cultivate plants over the long term by controlling environmental conditions in the phytotron such as temperature, relative humidity, CO2 concentration and light intensity. The results of our experiment indicate that plant seeds can germinate and grow even under an artificial gravity which changes sinusoidally from 2G to 4G.

Trace gases generated in closed plant cultivation systems and their effects on plant growth.

Interactions between plants and trace gases, especially ethylene, were investigated from two different viewpoints; ethylene is toxic for plant growth, whereas the ethylene release rate of plants can be utilized as a plant growth indicator. When lettuce plants and shiitake mushroom mycelium were cultivated in closed chambers, ethylene concentration increased with time. Ethylene was released both from lettuce plant and from shiitake mushroom mycelium. Dioctyl phthalate (DOP) and Dibutyl phthalate (DBP) were detected, and these concentrations reached 3.7 ngL-1 for DOP and 2.4 ngL-1 for DBP 4 days after closing. Organic solvents such as xylene and toluene and organic siloxane were detected with GCMS. Visible injury was observed in lettuce plants cultivated in the chambers and it seemed to result from trace contaminants such as DOP, DBP, organic solvents, dimethylsiloxane polymer, and ethylene. In order to obtain basic data of ethylene evolution from plants, ethylene concentration in a closed chamber in which the plants were cultivated under a controlled environment (25 degrees C air temperature, 60-70% relative humidity, 250-300 micromoles m-2 s-1 photosynthetic photon flux density (PPFD)) was measured. Lettuce (Lactuca sativa L. cv. Okayama) released ethylene more than Brassica rapa var. pervidis, Brassica campestris var. communis, and Brassica campestris var. narinosa. Ethylene release rate of intact lettuce plant was highly correlated with plant growth parameters such as dry weight, leaf area and photosynthetic rate. Ethylene release rates of intact lettuce plant were affected by cultivation conditions such as ambient CO2 concentration, light intensity and light/dark period. Increase in ambient ethylene level influenced lettuce growth even at the concentration of 0.1 microliter L-1. The level of ethylene inhibited leaf expansion and slightly accelerated chlorophyll degradation. It did not affect photosynthesis and transpiration, and also little affected dry matter accumulation. Thus, ethylene release characteristics were clarified and an effect of ethylene on lettuce growth was revealed. These findings are useful for determination of a threshold level of ethylene and a capacity of ethylene removal system in CELSS. On the other hand, a possibility of plant growth diagnosis by measuring ethylene concentrations was evaluated. As a result, it became clear that the measurement of ethylene concentration in CELSS is one of the useful non-destructive measurement methods for plant growth diagnosis. Further research is needed to investigate the applicability of the method to environmental stresses other than Ni and Co in nutrient solution.

Distribution of heavy metals in muscle, liver and kidney of northern fur seal (Callorhinus ursinus) caught off Sanriku, Japan and from the Pribilof Islands, Alaska.

The concentrations of iron, manganese, zinc, copper, cadmium, and mercury were determined in muscle, liver and kidney of 67 northern fur seals (Callorhinus ursinus) collected off Sanriku, Japan, and from the Pribilof Islands, Alaska. Almost all the elements except cadmium were highest in liver. Cadmium levels in kidney were higher than those in liver and muscle for all animals analyzed. Concentrations of mercury increased significantly with age in muscle, liver and kidney, as did iron levels in muscle and liver and cadmium levels in muscle, while manganese concentrations decreased with age in muscle and kidney. The kidney also showed decreased copper concentration with age. Cadmium concentrations of the northern fur seals in this study were higher than the other otariids, reflecting a predominantly squid diet. Concentrations of manganese and mercury were found to be higher in the fur seals caught off Sanriku than in animals from the Pribilof Islands, while those of zinc and cadmium were found to be lower. Variable concentrations of cadmium might have been attributed to those in seawaters. Discriminant analysis of heavy metal concentrations was used to identify habitat. Sixty-three of 67 animals (94%) were correctly classified using this technique. Heavy-metal concentrations in tissues may provide a useful method to elucidate the primary feeding grounds of fur seals.

Physical effects of dust on leaf physiology of cucumber and kidney bean plants.

The physical effects of dust accumulating on leaf surfaces, on leaf physiology, such as photosynthesis, transpiration, stomatal conductance and leaf temperature of cucumber and kidney bean plants were investigated by the use of chemically inert dust. It was found that dust decreased stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting. When dust of smaller particles was applied, the effect was greater. However, the effect was negligible when the stomata were closed during dusting. The dust decreased the photosynthetic rate by shading the leaf surface. The dust of smaller particles had a greater shading effect. Moreover, it was found that the additional absorption of incident radiation by the dust increased the leaf temperature, and consequently changed the photosynthetic rate in accordance with its response curve to leaf temperature. The increase in leaf temperature also increased the transpiration rate.

Plant growth and gas balance in a plant and mushroom cultivation system.

In order to obtain basic data for construction of a plant cultivation system incorporating a mushroom cultivation subsystem in the CELSS, plant growth and atmospheric CO2 balance in the system were investigated. The plant growth was promoted by a high level of CO2 which resulted from the respiration of the mushroom mycelium in the system. The atmospheric CO2 concentration inside the system changed significantly due to the slight change in the net photosynthetic rate of plants and/or the respiration rate of the mushroom when the plant cultivation system combined directly with the mushroom cultivation subsystem.

[A case report of mitral valve replacement for infective endocarditis in pregnancy].

Infective endocarditis in pregnancy is uncommon. A 37-week pregnant woman presented with infective endocarditis. Echocardiography revealed prominent mitral valve vegetations. The patient underwent cesarean section and a 2,800 g male infant was delivered. In order to prevent embolization, mitral valve replacement was performed 3 days after cesarean section with SJM valve. Both mother and child are doing well now.

Persistent organochlorine residues in northern fur seal from the Pacific coast of Japan since 1971.

The present study was conducted to determine the residue levels of persistent organochlorines such as PCB homologues, DDT and its metabolites, and HCH isomers in the ventral blubber of female northern fur seal (Callorhinus ursinus) collected off Sanriku, the Pacific coast of northern Japan, since 1971. Among the organochlorines examined, the concentrations of PCBs and DDTs were found to be high in all samples. The residue levels of these two contaminants showed a drastic reduction following maturity and then a slight increase after the retirement from pregnancy/menopause. Temporal variation of PCB and DDT residues showed maximum levels around 1976 and then decreased, whereas HCH residue levels revealed a very slow declining pattern. Considering the concentrations and compositions of the residues, the northern fur seal is likely to be exposed to organochlorine contamination deriving from global terms. In this context, continuous contamination has been foreseen with regard to PCB and HCH residues. The pattern of organochlorine residues indicated that the northern fur seal has higher metabolic capacity than Dall's porpoise, while it is comparable to those of larga seal and Steller sea lion.