Different Culture Media (different + culture_media)

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Selected Abstracts

Intraclonal variability in Daphnia acetylcholinesterase activity: The implications for its applicability as a biomarker

Liane Biehl Printes
Abstract The relationship between individual growth and acetylcholinesterase (AChE) activity was evaluated for Daphnia magna. Analysis on the influence of two different culture media on baseline AChE activity was performed with Daphnia similis. The results indicated an inverse relationship between D. magna body length and AChE activity. An increase in total protein, which was not proportional to an increase in the rate of the substrate hydrolysis (, absorbance/min), seems to be the reason for this inverse size versus AChE activity relationship. Therefore, toxicants such as phenobarbital, which affect protein and size but not AChE activity directly, have an overall affect on AChE activity. In contrast, the AChE inhibitor parathion altered AChE activity but not protein. Culture medium also had a significant affect on AChE activity in D. similis. Changes in total protein seem to be the main reason for the variations in baseline AChE activity in Daphnia observed in the different evaluations performed in this work. Therefore, AChE activity in Daphnia must be interpreted carefully, and variations related to changes in total protein must be taken into account when applying this enzyme as a biomarker in biological monitoring. [source]

Bile salts and cholesterol induce changes in the lipid cell membrane of Lactobacillus reuteri

M.P. Taranto
Abstract Aims: The objective of this study was to evaluate the effect of bile salts and cholesterol in the lipid profile of Lactobacillus reuteri CRL 1098 and to determine the relationship existing between these changes: the in vitro removal of cholesterol and the tolerance of the cells to acid and cold stress. Methods and Results:Lactobacillus reuteri CRL 1098 was grown in the following media: MRS (deMan Rogosa Sharpe; MC, control medium), MB (MC with bile salts), MCH (MC with sterile cholesterol) and MBCH (MC with bile salts and cholesterol). Fatty acids were determined by analytical gas,liquid chromatography, and phospholipids and glycolipids by colorimetric techniques. The cells from different culture media were subjected to cold and acid stress. The MB cultures displayed a decrease in phospholipids and a low ratio of saturated : unsaturated fatty acids. The presence of the unusual C18 : 0,10-OH and C18 : 0,10-oxo fatty acids was the prominent characteristic of the bile salts growing cells. The relative increase in glycolipids and the changes in the fatty acids profiles of the MB cells would be responsible for the cholesterol remotion. The changes induced by bile salts in the lipid profile did not improve the tolerance of L. reuteri CRL 1098 to freezing and acid stress. Conclusions: The changes in lipid profiles reported in this study would play a key role in the response of Lactobacilli to environmental stress. Significance and Impact of the Study: This work provides useful information about the effect of bile salts on the cell membrane of L. reuteri, a probiotic enterolactobacillus. The steady-state response of the cells subjected to bile stress seems to be the appropriate model for evaluating the bacterial behaviour in detergent-containing gastrointestinal tracts, where the bile salts stress would presumably be continuous. [source]

Cultural Characterization and Conidial Dimorphism in Colletotrichum sublineolum

E. A. Souza-Paccola
Abstract Anthracnose, caused by Colletotrichum sublineolum, is one of the most important diseases of sorghum in Brazil. This fungus showed conidial dimorphism when cultivated on solid or in liquid media. In solid media only falcate conidia were produced, whereas in liquid media the conidia were of variable size, but mostly oval. Wild strains, differentiated by their , and , esterase electrophoretic profiles, were assessed. The effect of different culture media on the production of both conidial types was evaluated. Unlike that of oval conidia, the production of falcate conidia was light-dependent. Some strains failed to produce falcate conidia in solid media, but all produced oval conidia in all the liquid media. The falcate conidia were uninucleate, but oval conidia contained one to three nuclei, although most were uninucleate. Both types of conidia induced symptoms in inoculable sorghum plants under controlled conditions. Both oval and falcate conidia produced mutants after exposure to UV light, and hyphal anastomoses occurred in crosses between mutant conidia carriers of complementary markers. The production of these oval conidia in C. sublineolum is an alternative to pathogenicity tests and genetic studies, especially for strains that sporulate poorly in solid culture media. [source]

Photodegradation of Soil Organic Matter and its Effect on Gram-negative Bacterial Growth

Gabriela N. Bosio
ABSTRACT To learn more about the role of the reactive oxygen species (ROS) in the production of bioavailable products of the dissolved organic matter, we investigate here the effect of the photolysis (,exc > 320 nm) of a soil extract (SE) on the growth of bacteria isolated from the same soil as used for obtaining the extract. Comparative experiments with Aldrich humic acid (AHA) as substrate were performed. The photodegradation of the SE was evaluated with different techniques,UV,visible absorption spectroscopy, fluorescence excitation emission matrices (EEM) and Fourier transform infrared spectroscopy (FTIR). Known ROS scavengers were employed to study the effect of photochemically produced ROS on the photodegradation of the substrates. To evaluate the effect of irradiation on the bioavailability of the SE and AHA, photolyzed and nonphotolyzed substrates were added to different culture media and the growth of Pseudomonas sp. isolated from the soil and a strain of Escherichia coli were studied. The different results obtained were assigned to the dissimilar metabolisms of both bacteria. [source]

Infection of Gymnodinium sanguineum by the Dinoflagellate Amoebophryasp.: Effect of Nutrient Environment on Parasite Generation Time, Reproduction, and Infectivity

ABSTRACT. Preliminary attempts to culture Amoebophrya sp., a parasite of Gymnodinium sanguineum from Chesapeake Bay, indicated that success may be influenced by water quality. To explore that possibility, we determined development time, reproductive output, and infectivity of progeny (i.e. dinospores) for Amoebophrya sp. maintained on G. sanguineum grown in four different culture media. The duration of the parasite's intracellular growth phase showed no significant difference among treatments; however, the time requiredfor completion of multiple parasite generations did, with elapsed time to the middle of the third generation being shorter in nutrient-repletemedia. Parasites of hosts grown in nutrient-replete medium also produced three to four times more dinospores than those infectinghosts under low-nutrient conditions, with mean values of 380 and 130 dinospores/host, respectively. Dinospore production relative tohost biovolume also differed, with peak values of 7.4 per 1,000 ,m3 host for nutrient-replete medium and 4.8 per 1,000 ,m3 host fornutrient-limited medium. Furthermore, dinospores produced by "high-nutrient" parasites had a higher success rate than those formedby "low-nutrient" parasites. Results suggest that Amoebophrya sp. is well adapted to exploit G. sanguineum populations in nutrient-enrichedenvironments. [source]

Improved Paclitaxel and Baccatin III Production in Suspension Cultures of Taxusmedia

Rosa M. Cusidó
A cell suspension culture of Taxus media was established from a stable callus line of this species. The growth rate and production of paclitaxel and baccatin III of this cell suspension were significantly increased during the shake flask culture in its respective optimum media for cell growth and product formation, which were selected after assaying 24 different culture media. The highest yields of paclitaxel (2.09 mg L,1) and baccatin III (2.56 mg L,1) in the production medium rose (factors of 7.0 and 3.0, respectively) in the presence of methyljasmonate (220 ,g g,1 FW). When the elicitor was added together with mevalonate (0.38 mM) and N -benzoylglycine (0.2 mM), the increase in the yields of paclitaxel and baccatin III was even higher (factors of 8.3 and 4.0, respectively). Thereafter, a two-stage culture for cell suspension was carried out using a 5,l stirred bioreactor running for 36 days, the first stage being in the cell growth medium until cells entered their stationary growth phase (12 days) and the second stage being in the production medium supplemented with the elicitor and two putative precursors in the concentrations indicated above. Under these conditions, 21.12 mg L,1 of paclitaxel and 56.03 mg L,1 of baccatin III were obtained after 8 days of culture in the production medium. [source]

Comparison of Growth and Recombinant Protein Expression in Two Different Insect Cell Lines in Attached and Suspension Culture

R. A. Taticek
Culture conditions required for obtaining maximum recombinant protein concentrations from two cell lines, Spodoptera frugiperda (IPL,-Sf21-AE) and Trichoplusia ni (Tn 5,-1,4), were determined in this work. Conditions studied include mode of culture (suspended vs attached), agitation rates, inoculum sizes, cell concentration at the time of infection, and various serum-free media (SFM). Results were compared with the performance of attached cultures in TnM-FH with 10% fetal bovine serum. Growth rates in the different culture media tested were similar, but the cell numbers achieved (i.e., yield) improved 2 to 2.7-fold in SFM over cultures in TnM-FH. Agitation rates of 150,160 rpm were necessary for maximum growth of suspended Tn 5,-1,4 cells compared to 125,150 rpm for Sf-21 cells. An inoculum size of 5 × 105 cells/mL gave good growth rates and optimum biomass yields for both cell lines. Cultures of both cell lines were infected with viruses encoding for ,-galactosidase or human secreted alkaline phosphatase (seAP). Protein expression in TnM-FH in attached culture showed that Tn 5,-1,4 cells are 2,4.5 times more productive on a per cell basis than Sf-21 cells grown under similar conditions. Production of ,-galactosidase in Sf-21 cells increased 50% in suspension cultures with SFM compared to attached cultures in TnM-FH, but seAP expression was essentially unchanged by culture techniques. The Tn 5,-1,4 cells produced 2.6,4.4 and 2.7,3 times more ,-galactosidase and seAP, respectively, in SFM in suspension compared to Sf-21 cells. EX-CELL 401 and Sf900-II were formulated as optimized SFM for Sf cell lines. However, in Sf-21 cultures EX-CELL 400 performed better than the other two media, as it increased the ,-galactosidase yield up to 25%. Surprisingly, EX-CELL 401 was the best medium for the production of ,-galactosidase by Tn 5,-1,4 cells, resulting in 25% and 69% higher volumetric and specific yields, respectively, compared to EX-CELL 405 which was formulated for this specific cell line. These results show that even when culture media are designed for maximal growth of a specific cell line, other media may provide the best conditions for protein production. [source]