Growth medium

About: Growth medium is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 59171 citations. The topic is also known as: culture medium & culture media.

Uptake of trehalose by Saccharomyces cerevisiae.

Abstract: SUMMARY: Trehalose, a storage sugar of baker's yeast, is known not to be metabolized when added to a cell suspension in water or a growth medium and to support growth only after a lag of about 10 h. However, it was transported into cells by at least two transport systems, the uptake being active, with a pH optimum at 5·5. There was no stoicheiometry with the shift of protons into cells observed at high trehalose concentrations. Trehalose remained intact in cells and was not appreciably lost to a trehalose-free medium. The uptake systems were present directly after growth on glucose, then decayed with a half-life of about 25 min but could be reactivated by aerobic incubation with trehalose, maltose, α-methyl-D-glucoside, glucose or ethanol. The uptake systems thus induced were different as revealed by competition experiments. At least one of the systems for trehalose uptake showed cooperative kinetics. Comparative analysis with other disaccharides indicated the existence in Saccharomyces cerevisiae, after induction with trehalose, of at least four systems for the uptake of α-methyl-D-glucoside, four systems for maltose, together with the two for trehalose, variously shared by the sugars, the total of α-glucoside-transporting systems being five.

Rhizobia enhance acquisition of phosphorus from different sources by soybean plants

Abstract: Some rhizobia can convert insoluble P into available forms for plant growth but the underlying mechanisms for this are not understood. In this study, the function of rhizobia in P acquisition from P sources for soybean was studied. Four rhizobial strains were employed to evaluate their phosphate-solubilizing (PS) activity, their ability to mediate pH changes in growth medium for different P sources, and IAA production. A sand culture experiment using different P sources was carried out to characterize P acquisition changes of soybean plants with or without rhizobium inoculation. Rhizospheric acidification in soybean was further analyzed in hydroponics. Our results showed that all the tested rhizobial strains exhibited significant PS activity for different P sources in the order of Ca-P>Al-P>Phy-P≥Fe-P as indicated by the halo/colony ratio technique and increased Pi percentage in the solid and liquid phases, respectively. Furthermore, all of the rhizobial strains could acidify the growth medium for all P sources except Phy-P, but only three of them produced IAA. Compared to non-nodulated plants, the nodulated plants had greater plant biomass and P content in sand culture for all the tested P sources, especially for Ca-P. Moreover, H+ and total acid exudation was more significantly enhanced in the nodulated plants in hydroponics. Our results suggested that the PS ability of rhizobia is more related to acidification of the growth medium than IAA production. Rhizobium inoculation could enhance P acquisition in soybean, especially on soils where Ca-P is the primary P source, and the primary mechanism for rhizobial-mediated P solubilization appears to be via Pi remobilization of nodulated roots through rhizospheric acidification.

Effect of salt stress on lipid composition and membrane fluidity of the salttolerant yeast Zygosaccharomyces rouxii

Abstract: Summary: When the salt-tolerant yeast Zygosaccharomyces rouxii was grown in YPD medium containing 15% (w/v) NaCl, the relative amounts of C16:1 and C18:1 fatty acids in acyl lipids increased and those of C18:0 and C18:2 acids decreased both in whole cells and in crude plasma membrane preparations, as compared with cells grown in YPD medium alone. The proportions of C12:0 and C14:0 acids, which are minor components of yeast lipids, decreased in whole cells and markedly increased in plasma membranes when 15% NaCl was included in the growth medium. The degree of unsaturation of fatty acids in the membranes and in whole cells decreased in the presence of 15% NaCl in the culture medium. The amount of free ergosterol in the membranes of cells grown in 15% NaCl increased to 2·9 times that of control cells. The ratio of ergosterol to phospholipid increased to 5 times that of control cells, whereas the ratio of phospholipid to protein in the membranes of cells grown in 15% NaCl decreased to less than half that of control cells. The fluorescence polarization value of DPH (1,6-diphenyl-1,3,5-hexatriene) in membranes of cells grown in 15% NaCl was 1·2 times higher than that for membranes from control cells, indicating a decrease in membrane fluidity in the presence of a high concentration of NaCl.

Prostacyclin and prostaglandin E2 secretions by bovine pulmonary microvessel endothelial cells are altered by changes in culture conditions.

Abstract: The isolation and culture of pulmonary microvascular endothelial (MVE) cells from bovine lungs were established. Primary and early passaged cultures grew best in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% equine plasma-derived serum, bovine retinal growth extract (1%), and heparin (90 micrograms/ml) on gelatin coated plates. A second tissue culture procedure was prepared in which the isolation technique was the same except the culture medium consisted of DMEM supplemented with 10% plasma-derived serum. Either growth medium produced homogeneous, long term, serial cultures for up to 16 passages. MVE cells were characterized in part based on their morphology by light and electron microscopy and positive reaction to Factor VIII-related antigen and uptake of 1,1'-dioctacecyl-1,3,3,3'3-tetramethyl-indocarbocyanine perchlorate acetylated low density lipoprotein (Dil-Ac-LDL). MVE cells were also positive for angiotensin-converting enzyme (ACE) activity and the presence of ACE was localized on the cells by indirect immunofluorescence. MVE cells maintained in the presence of heparin and growth factor principally synthesized prostaglandin (PG) E2 (1512 +/- 159 pg/mg protein at 15 min) and smaller amounts of prostacyclin (PGI2) and thromboxane (Tx) A2 (316 +/- 43 and 588 +/- 105 pg/mg protein/15 min respectively) as measured by radioimmunoassay. However, prostanoid release was not elevated from basal levels upon incubation with arachidonic acid, bradykinin, or ionophore A23187. In contrast, MVE cells cultured without heparin and growth factor secreted more PGI2 than PGE2 (862 +/- 84 and 89 +/- 12 respectively). Incubation with arachidonic acid, bradykinin, or ionophore A23187 induced significant increases in PGI2 and PGE2 production (P less than 0.01). Pulmonary artery endothelial (PAE) cell cultures used as a control for comparison predominantly synthesized PGI2. These findings suggest that in vitro the vessel source and culture conditions may qualitatively and quantitatively affect the pattern and levels of prostanoid synthesized and secreted.

Effect of bioaccumulation of cadmium on biomass productivity, essential trace elements, chlorophyll biosynthesis, and macromolecules of wheat seedlings

Abstract: Soil contamination with heavy metals has become a worldwide problem, leading to losses in agricultural yield and hazardous human health effects as they enter the food chain. The present investigation was undertaken to examine the influence of cadmium (Cd2+) on the wheat (Triticum aestivum L.) plant. Cd2+ accumulation and distribution in 3-wk-old seedlings grown in nutrient medium containing varying concentrations of Cd2+ (control, 0.25, 0.50, 1.0, 2.5, and 5.0 mg/L) was monitored. The effect of varying Cd2+ concentrations up to 21 d on biomass productivity, plant growth, photosynthetic pigments, protein, amino acids, starch, soluble sugars, and essential nutrients uptake was studied in detail to explore the level up to which the plant can withstand the stress of heavy metal. Plants treated with 0.5, 1.0, 2.5, and 5.0 mg/L Cd2+ showed symptoms of heavy-metal toxicity as observed by various morphological parameters which were recorded with the growth of plants. The root, shoot-leaf length and the root, shoot-leaf biomass progressively decreased with increasing Cd2+ concentration in the nutrient medium. Cd2+ uptake and accumulation was found to be maximum during the initial growth period. Cd2+ also interfered with the nutrients uptake, especially calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe2+), zinc (Zn2+), and manganese (Mn2+) from the growth medium. Growth reduction and altered levels of major biochemical constituents such as chlorophyll, protein, free amino acids, starch, and soluble sugars that play a major role in plant metabolism were observed in response to varying concentrations of Cd2+ in the nutrient medium. In the present study, the effects of Cd2+ on growth, biomass productivity, mineral nutrients, chlorophyll biosynthesis, protein, free amino acid, starch, and soluble sugars in wheat plants was estimated to establish an overall picture of the Cd2+ toxicity at structural and functional levels.