Growth and photosynthesis in seedlings of Hizikia fusiformis (Harvey) Okamura (Sargassaceae, Phaeophyta) cultured at two different temperatures

This study examined temperature acclimation, growth, and photosynthetic characteristics of the zygote-derived seedlings of Hizikia fusiformis (Harvey) Okamura (Sargassaceae). The seedlings were cultured at 15°C or 25°C for 4 weeks. The average relative growth rate was significantly higher in seedlings acclimated at 25°C. The photosynthetic rate measured at 15°C was much higher in seedlings grown at 15°C than those grown at 25°C, indicating photosynthetic acclimation to a lower temperature. At 35°C, the photosynthetic rate of 15°C-grown seedlings was drastically decreased, whereas that of 25°C-grown seedlings was significantly increased. The maximum relative electron transport rate (rETR_max) measured at the respective growth temperature was significantly higher in seedlings grown at 25°C than at 15°C. At a measuring temperature of 35°C, the rETR_max in both 15°C- and 25°C-grown seedlings were considerably reduced with regard to those measured at 15°C or 25°C. Our results suggested that, compared with the seedlings grown at 25°C, those acclimated at a lower temperature could be disadvantaged under adverse conditions such as increased temperatures.     

Growth of and omega-3 fatty acid production by Phaeodactylum tricornutum under different culture conditions

Detailed studies were carried out on the effects of nitrogen source, phosphate, sodium chloride, growth factors, precursors, CO2, temperature, initial pH, and inoculum size on biomass and eicosapentaenoic acid (EPA) production by Phaeodactylum tricornutum. The EPA content of total fatty acids increased with increasing concentrations of nitrate and urea. Sodium chloride was not required for growth or EPA production. While vitamins B1 and B12 did not affect growth significantly, EPA yield was increased by 65% by B12 supplementation. Maximum EPA production occurred when the air gassing supply was supplemented with 1% CO2. Optimum culture temperature and initial pH for EPA production were 21.5 to 23 degrees C and 7.6, respectively. EPA yields of up to 133 mg/liter of culture were observed. EPA constituted up to 30 to 40% of total fatty acids.     

Growth of and omega-3 fatty acid production by Phaeodactylum tricornutum under different culture conditions.

Detailed studies were carried out on the effects of nitrogen source, phosphate, sodium chloride, growth factors, precursors, CO2, temperature, initial pH, and inoculum size on biomass and eicosapentaenoic acid (EPA) production by Phaeodactylum tricornutum. The EPA content of total fatty acids increased with increasing concentrations of nitrate and urea. Sodium chloride was not required for growth or EPA production. While vitamins B1 and B12 did not affect growth significantly, EPA yield was increased by 65% by B12 supplementation. Maximum EPA production occurred when the air gassing supply was supplemented with 1% CO2. Optimum culture temperature and initial pH for EPA production were 21.5 to 23 degrees C and 7.6, respectively. EPA yields of up to 133 mg/liter of culture were observed. EPA constituted up to 30 to 40% of total fatty acids.     

Growth, auxin requirement, and indole-3-acetic acid content of cultured crown-gall and habituated tissues of tobacco

Abstract. We used radioimmunoassay to compare the indole-3-acetic acid (IAA) concentration in cultured auxinautonomous tissues of Nicotiana tabacum L. cv.'Havana 425'that differ in growth rate, auxin requirement, capacity for organogenesis, and proximal cause of transformation. Lines HT37 and HB6 were crown-gall tissues transformed by the T37 and B6 strains of Agrobacterium tumefaciens . The tissue line 156AH, like the crown-gall lines, was auxin and cytokinin autotrophic, but arose spontaneously in culture and did not result from crown-gall transformation. The IAA content of the lines was variable and between 10⁻⁷ and 10⁻⁶ moles kg⁻¹ fresh weight. This same range of IAA concentration was found in growing leaf tissues on the plant. IAA concentrations were 2–5 fold higher in HB6 than HT37 during the first few days of culture, and exogenous auxin induced the teratomatous HT37 tissue to grow in an unorganized fashion suggesting that auxin plays a role in regulating tumor morphology. The major difference between genetically transformed crown-gall tissues and the auxin-cytokinin autotrophic tissue line was that net IAA production continued to rise for several weeks of culture in tumor tissues but only for the first few days of culture in the autotrophic tissue.     

Number, activity and thermostability of the electrophoretic forms of acid phosphatase in Amoeba proteus, cultured at different temperatures

In free-living amoebae (Amoeba proteus, strain B), cultured at 10 and 25 degrees C, we compared the number, activity, and thermostability of separate electromorphs of Triton-soluble acid phosphatase (AcP) revealed by disc-electrophoresis in polyacrylamide gel using 2-naphthyl phosphate (pH 4.0) as a substrate. No differences in the number of AcP electromorphs and their mobility were observed at both these temperatures. The total activity of AcP electromorphas per unit of cellular protein and their total thermostability were lower in amoebae acclimated to 10 degrees C than to 25 degrees C. The above decrease may be a consequence of a simultaneous decrease in the activity and thermostability of two tartrate-sensitive electromorphs, both being of lysosomal nature. The total activity and thermostability of tartrate-resistant AcP electromorphs did not differ in amoebae acclimated to the two above temperatures. In amoebae cultured at 10 degrees C the fall of activity and thermostability of lysosomal AcP correlates with the decrease in their primary cell thermoresistance and phagocytic activity. The obtained results confirm the earlier conclusion (Vysotskaya et al., 1994) that lysosomes may be involved in acclimation of electrothermal animals to changing environmental temperatures.     

Growth and lactic acid production ofPediococcus pentosaceus at different gas environments,temperatures, pH values and nitrite concentrations

Summary In order to obtain a better understanding of the behaviour ofPediococcus pentosaceus in food products as well to facilitate the designing of industrial production processes for the organism, the growth and lactic acid production ofPediococcus pentosaceus in a complex glucose medium was followed in batch cultures at different gas environments (CO₂, air, N₂ and static cultures without gasflow), temperatures (10–50°C), pH (4.3–7.3) and nitrite concentrations (0–700 ppm). Optimal growth was obtained in CO₂ at 40°C and pH 6.3 and resulted in a maximum specific growth rate ( _max) of 1.27 h^–1. In static culture at 40°C and pH 6.3 the _max was 1.21 h^–1. The _max was, compared with static culture, reduced in air (12%) and nitrogen (26%). At 10°C the _max was reduced by 99% and at 50°C by 88%. The reduction at pH 4.3 and 7.3 was 65% and 57%, respectively. Nitrite did not affect the _max at any pH but increased the lag phase at pH 4.3 by a factor of 12. The lactic acid production was linked to the growth. The total amount of lactic acid produced was the same in all the tested gases and nitrite concentrations and also within the wide temperature range (15–45°C) and pH range (5.3–7.3). Mainly L(+)-lactic acid was produced during the exponential growth phase, but after this growth declined about 30% of the L(+)-lactic acid was converted to D(–)-lactic acid. The lactic acid product yield and the cellmass yied were both affected by the temperature but not by the pH.     

Growth,abscisic acid content,and carbon isotope composition in wheat cultivars grown under different soil moisture

Changes in dry matter accumulation and allocation, abscisic acid content and carbon isotope composition of three wheat cultivars from dry, middle and wet climate regions were recorded at full maturity after exposure to different watering regimes (100, 50 and 25 % field capacity). Compared with the wet climate cultivar, the dry climate cultivar showed lower stem height, total leaf area, total dry biomass and total grain dry mass, and higher root/shoot ratio, abscisic acid content and carbon isotope composition under all watering regimes. Both water-limited treatments significantly reduced leaf growth and increased dry matter allocation into the roots leading to a significant raise of root/shoot ratio in all cultivars tested. In addition, drought affected morphological and physiological properties more in the dry climate cultivar than in the wet climate cultivar.     

Growth,trichome size and akinete production of Cylindrospermopsis raciborskii (cyanobacteria) under different temperatures: Comparison of two strains isolated from the same pond

Coiled morphotype Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju that forms a water bloom in a shallow pond in northern Taiwan exhibits a negative correlation between trichome size and temperature. To investigate how temperature influences the growth and trichome size of C. raciborskii, two C. raciborskii strains isolated from the pond in August and February were grown at three temperatures (18, 24 and 30°C). Both strains exhibited the lowest and highest specific growth rates at 18°C and 24°C, respectively, and the trichomes became the largest at 18°C. However, specific growth rates of the strain isolated in August exceeded those of the strain isolated in February, and the trichomes of the strain isolated in February were larger than those of the strain isolated in August regardless of temperature. Moreover, although both strains produced larger numbers of akinetes at higher temperatures, the strain isolated in August produced many more akinetes than did the other. These findings suggest that the two strains are not identical, leading to the conclusion that the C. raciborskii population in the pond consists of at least two ecotypes. Large trichome formation and akinete production are thought to be different types of countermeasure against cold of C. raciborskii, and the patterns of investment in developing these functions seemed to vary between the strains.     

n-3 Fatty acid content in eggs laid by hens fed with marine algae and sardine oil and stored at different times and temperatures

Inclusion of sardine oil (SO) in diets for laying hens significantly increases the n-3 polyunsaturated fatty acids (PUFAs) in the egg, but these are more sensitive to oxidation, so the storage time and temperature can cause a decrease in their concentration. Therefore, the objective of this study was to determine the effect of algae Macrocystis pyrifera, Enteromorpha spp., and Sargassum sinicola on n-3 PUFA contents in eggs from laying hens fed diets supplemented with sardine oil and stored for different times (0, 15, and 30 days) and temperatures (20°C and 4°C), for 8 weeks. One hundred and twenty hens were divided into four treatments: T1 (commercial diet), T2 (2% SO?+?10% M. pyrifera), T3 (2% SO?+?10% Enteromorpha), and T4 (2% SO?+?10% S. sinicola). At the end, 50 eggs per treatment were collected to quantify total lipids and egg n-3 PUFAs at different times (0, 15, and 30 days) and temperatures (20°C and 4°C) of storage. The results were analyzed using a 3?×?3?×?2 factorial design, and Tukey test to compare means (P?<?0.05). The results show that M. pyrifera and S. sinicola had a better effect on eicosapentaenoic acid, while Enteromorpha was better for docosahexaenoic acid. In relation to time and temperature, the content of the fractions analyzed in the three treatments at 15 days/4°C had a lower loss compared with eggs analyzed at day 0/20°C.     

Growth,toxicity and oxidative stress of a cultured cyanobacterium (Dolichospermum sp.) under different CO2/pH and temperature conditions

Cyanobacteria blooms are a worldwide nuisance in fresh, brackish and marine waters. Changing environmental conditions due to upwelling, changed mixing conditions or climate change are likely to influence cyanobacteria growth and toxicity. In this study, the response of the toxic cyanobacterium Dolichospermum sp. to lowered pH (?0.4 units by adding CO₂) and elevated temperature (+4°C) in an experimental set‐up was examined. Growth rate, microcystin concentration and oxidative stress were measured. The growth rate and intracellular toxin concentration increased significantly as a response to temperature. When Dolichospermum was exposed to the combination of elevated temperature and high CO₂/low pH, lipid peroxidation increased and antioxidant levels decreased. Microcystin concentrations were significantly correlated with growth rates. Our results show, although oxidative stress increases when exposed to a combination of high CO₂/low pH and high temperature, that growth and toxicity increase at high temperature, suggesting that the cyanobacterium in general seems to be fairly tolerant to changes in pH and temperature. Further progress in identifying biological responses and predicting climate change consequences in estuaries experiencing cyanobacteria blooms requires a better understanding of the interplay between stressors such as pH and temperature.     

Action mechanism of vascular spasmolytics. 5. Drug-related relaxation and adenosine-3',5'-monophosphate content of isolated coronary arteries under conditions of fluoride-induced contracture]

Tetracaine and SKF 525-A as well as stimulators of adenylate cyclase and inhibitors of the nucleoside-3',5'-monophosphate phosphodiesterase have spasmolytic effects. At the fluoride-iuduced contracture -- a form of contracture independent of extracellular calcium -- tetracaine and SKF 525-A effect an additional increase in muscular tension. Their relaxing effect evidently presupposes a functioning calcium exchange. Drugs acting on the cAMP system have invariably spasmolytic effects at this contracture model, although they produced no change of the cAMP content under these conditions. An increase in total cAMP content is not obviously a necessary condition for the occurrence of drug-induced relaxation.