Nitrogen uptake and growth responses of seedlings of the brown seaweed Sargassum hemiphyllum under controlled culture conditions

Various saltgrass clones were studied hydroponically, using Hoagland solution, in a greenhouse to evaluate their DM weights and nitrogen uptake under control and salt stress conditions. Treatments included control (no added salt) and plants grown under NaCl salinity. Twelve clones were grown with 4 replications of each treatment in a RCB design trial. Ammonium sulfate, 5.3%15N was used to enrich the plants by adding 5 mg15N as 22.931 mg (15NH4)2SO4, per liter of the culture solution per day. Plant shoots were harvested weekly, oven-dried at 65°C, and DM weights were recorded. At the last harvest, plant roots were also harvested, oven-dried at 65°C, and DM weights were determined. Harvested plant materials were analyzed for total-N and15N contents. The results showed non-significant differences in shoot DM weights and total-N and15N concentrations and contents in salinized plants compared with the controls. Total-N and15N concentrations of the roots were higher than that of the shoots under either control or saline condition. Overall, due to the high degree of salt tolerance of saltgrass, the results showed generally no difference in nitrogen uptake by most of the clones under salt stress compared with the control plants.

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GROWTH RESPONSES OF FIVE NON TOXIC ALEXANDRIUM SPECIES (DINOPHYCEAE) TO TEMPERATURE AND SALINITY

Marine Research in Indonesia ◽

10.14203/mri.v32i2.454 ◽

1970 ◽

Vol 32 (2) ◽

pp. 189-195

Author(s):

Po-Teen Lim ◽

Chui-Pin Leaw ◽

Shinnosuke Kaga ◽

Katsushi Sekiguchi ◽

Takehiko Ogata

Keyword(s):

Salinity Tolerance ◽

Variable Temperature ◽

Culture Conditions ◽

Temperate Species ◽

Salinity Range ◽

Tropical Species ◽

Optimum Growth ◽

Growth Responses ◽

Clonal Cultures ◽

Higher Temperature

Growth response of five clonal cultures of Alexandrium obtained from tropical and temperate waters were examined. Experiments were carried out in eighteen variable temperature-salinity conditions (temperatures of 15 °C, 20°C, and 25°C; salinities between 5 to 30 psu) under constant illumination of 150 ± 10.0 Amol m-2 s-' at 15:9 light:dark photo-cycle. Our results showed optimum growth of all Alexandrium species at 20 - 25°C. The salinity range for optimum growth however varied among the species. Growth rates of A. eine, A. insuetum, and A. fraterculus (0.28 — 0.37 day') were higher than those of A. leei and A. pseudogoniaulax under the same culture conditions (0.14 —0.22 day-'). The three temperate species showed positive growth at suboptimum temperature, 15°C, but the tropical species did not grow and died off. Salinity tolerance of the five species in decreasing order was A. pseudogoniaulax > A. leei > A. insuetum > A. affine > A. fraterculus. Results of the present study showed vast variations in salinity tolerance among the Alexandrium species regardless the geographical origins. Adaptation of the temperate species at higher temperature indicated that the species might proliferate in warm tropical waters.

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Effects of environmental parameters on net photosynthesis of a free-living brown seaweed,Cystoseira barbata formarepens: determination of optimal photosynthetic culture conditions

Journal of Applied Phycology ◽

10.1007/bf02179786 ◽

1990 ◽

Vol 2 (3) ◽

pp. 281-287 ◽

Cited By ~ 13

Author(s):

D. Baghdadli ◽

G. Tremblin ◽

M. Pellegrini ◽

A. Coudret

Keyword(s):

Brown Seaweed ◽

Environmental Parameters ◽

Net Photosynthesis ◽

Culture Conditions ◽

Free Living ◽

Cystoseira Barbata

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Effects of insulin and insulin-like growth factor I on growth of human leukemia cells in serum-free and protein-free medium

Blood ◽

10.1182/blood.v72.1.66.bloodjournal72166 ◽

1988 ◽

Vol 72 (1) ◽

pp. 66-72

Author(s):

J Sinclair ◽

D McClain ◽

R Taetle

Keyword(s):

Growth Factor ◽

Culture Conditions ◽

Leukemia Cells ◽

Human Leukemia ◽

Growth Responses ◽

Free Medium ◽

Serum Free ◽

Human Leukemia Cells ◽

Igf I ◽

Protein Free Medium

Human myeloid leukemia cells (HL60) and malignant lymphocytes (Namalwa) were grown in protein-free, Fe-supplemented media and used to study growth responses to insulin and insulin-like growth factor 1 (IGF-I). HL60 cells previously grown in serum-free medium containing microgram quantities of insulin showed an 18-fold reduction in cumulative cell production when grown without insulin. However, the same cells showed reduced or absent growth stimulation with 1 to 100 ng/mL insulin or IGF- I for at least four days following insulin deprivation, indicating that culture conditions modified insulin and IGF-I responses. When the same cells were grown in Fe-supplemented, protein-free medium (RPMI-Fe), insulin and IGF-I caused dose-dependent stimulation of HL60 cell growth with half-maximal stimulation at nanogram concentrations. Namalwa cells grown in protein-free medium showed no response to either hormone. Radioligand binding showed the presence of insulin and IGF-I receptors on both HL60 and Namalwa cells grown in RPMI-Fe. HL60 cells grown in fetal bovine serum had higher, and cells grown with microgram quantities of insulin dramatically reduced, insulin binding. Competitive binding studies and cultures with anti-IGF-I receptor antibody showed insulin and IGF-I stimulated growth through their respective specific receptors. Both insulin and IGF-I stimulate growth of some cultured human leukemia cells, but the presence of insulin or IGF-I receptors alone does not predict growth responses. Culture conditions affect both cellular responses and ligand binding by these hormones and must be closely controlled to study growth responses.

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