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eBook: HPLC-UV-Vis Absorption and Charged Aerosol Detection: Dietary Supplements and Botanical Natural Products Applications Notebook Complex Samples, Powerful Chromatographic Analysis Product Literature

Article: Benefits of customizable cell culture media in therapeutic development Product Literature

Product Specification: SR0234B ONE BROTH-LISTERIA SELECTIVE SUPPLEMENT (V2) Product Literature

Product Specification: SR0163 NEOMYCIN SELECTIVE SUPPLEMENT (V1) Product Literature

Prebiotics Modulate the Effects of Antibiotics on Gut Microbial Diversity and Functioning in Vitro. Citations & References

  • Authors: Johnson LP, Walton GE, Psichas A, Frost GS, Gibson GR, Barraclough TG
  • Journal: Nutrients 2015; (7):6 4480-4497
  • PubMed ID: 26053617

I suspect mycoplasma is affecting the growth rate of my culture. How can I test for it? Product FAQ

Answer

There are several options. Our first recommendation is to use the Invitrogen MycoFluor Mycoplasma Detection Kit.

Mycoplasmas are small, self-replicating prokaryotes (0.3 - 0.8 mm diameter), that lack a cell wall and have the ability to adsorb onto host cells. Mycoplasma is one of the most serious forms of cryptic contamination and its presence is not detected unless appropriate tests are made or until some aspect of cell behavior is noticed to have changed. Between 15 and 50% of cell lines submitted to cell banks are contaminated with mycoplasma. Mycoplasma spreads readily among cell lines via reagents and media, the operator and the work surface.

The presence of mycoplasma may invalidate the results obtained with that culture. The presence of mycoplasma-infected cultures can result in the shut-down of the entire laboratory until the infection can be eliminated, whereupon complete restocking is required. The origin of contamination is usually traced to mycoplasma present in animal (bovine) serum or to human oral mycoplasma transferred by droplet infection during cell culture. The simplest test for the detection of mycoplasma in cultures is the use of a fluorescent dye which binds directly to DNA causing fluorescence (e.g. Hoechst 33258) which can be seen by fluorescence microscopy. Mycoplasma positive cells will show intense fluorescent spots on the plasma membranes or show filaments which may be absorbed onto the cells. Uncontaminated cells show only brightly fluorescent cell nuclei. The technique is rapid (less than 30 minutes), but requires heavy contamination (10E6 mycoplasma/ml) to produce a clear positive result. If however, the suspect cells are co-incubated for 2-4 days with an "indicator" cell line (such as 3T3) which is particularly suitable for demonstration of positive staining, then sensitivity can be substantially increased. Microbiological culture techniques are available that operate at a greater sensitivity, but it can take up to 21 days to obtain a result, a positive control is needed, and the result may require expert interpretation.

A variety of PCR-based methods are available, some of which have been utilized as commercially available detection kits. It is recommended to use a combination of DNA staining and a PCR-based method once every 3 months for all growing cultures in the laboratory and for every new cell line as it enters the laboratory. In addition, all Master and Working Cell Banks should be tested at the time of freezing. Quality control and good working practice will reduce potential problems. It is important that frozen stocks are created immediately after testing and re-tested before distribution. If cells are cultured for more than 3 months after testing, they should be re-tested. Regulatory bodies now insist that cell cultures used for the production of reagents for diagnostic kits or therapeutic agents are free from mycoplasma infection. Also, some scientific journals have the policy of requiring statements from authors that the culture work reported in those journals is carried out with mycoplasma-free cells. Normally, when contamination with mycoplasma is apparent, the recommendation would be to discard the cultures and start again. If necessary, and only if the contamination is not extensive, then it is often possible to rescue the cells by treatment with one of the commercially available antibiotics. This must only be considered for a remedial action, not as a routine supplement to growth media (and thereby a substitute for good cell culture practice).

Answer Id:: E3983

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I'm getting a low yield of virus when using the Bac-to-Bac baculovirus expression system. Why is this, and what can I do to improve my yield? Product FAQ

Answer

Please see the following reasons and suggestions to improve yield:

- Low transfection efficiency: We recommend using our Cellfectin II Reagent for transfection; perform the transfection in Grace's Medium, Unsupplemented and ensure no supplements, FBS, or antibiotics are present during the transfection. Harvest the viral supernatant when signs of infection are visible (typically >96 hr post-transfection).
- Cells are plated too sparsely; check recommended cell densities.
- Use too much or too little Cellfectin II Transfection Reagent: Optimize amount used.
- Time of incubation with DNA:lipid complexes is too short or too long: Optimize incubation time (3-8 hr).
- Recombinant bacmid DNA is degraded: Check the quality of your recombinant DNA by agarose gel electrophoresis prior to transfection; prepare bacmid DNA using PureLink HiPure Plasmid DNA Miniprep or Maxiprep Kit.
- Bacmid DNA is not pure (contains recombinant and empty bacmid): Screen other DH10Bac transformants and perform plaque purification to isolate recombinant baculovirus.

Answer Id:: E9451

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I performed an LR reaction, followed by transfection into Sf9/Sf21 insect cells, but do not see any signs of infection even though it's been 72 hours. What should i do? Product FAQ

Answer

Please see our recommendations below:

- Check the LR reaction by PCR analysis prior to transfection into insect cells.
- We recommend using Grace's Insect Cell Culture Medium, Unsupplemented during the transfection experiment instead of serum-free medium, as components in serum-free medium may interfere with transfection.
- Ensure that FBS, supplements, or antibiotics are not included during transfection, as the proteins in these materials can interfere with the Cellfectin II Reagent.
- Use the LR recombination reaction using the pENTR/CAT plasmid as a positive control and Cellfectin II Reagent only (mock transfection) as a negative control.
- Ensure that cells are in the log phase of growth with >95% viability, and the amount of cells are in accordance with the suggestions in the manual.
- Cells may not show signs of viral infection for up to a week depending on transfection efficiency; continue culturing and monitor cells daily for signs of infection.

Answer Id:: E9459

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3D Cell Culture Handbook Product Literature

User Guide: CellSensor Gli-bla NIH3T3 Cell-based Assay Manual / Product Insert

  • Version: 2.0
Catalog #
  • K1188(Blocked)
  • K1642B

User Guide: GeneBLAzer GPR54‑NFAT-bla CHO‑K1 Cell–Based Assay Manual / Product Insert

  • Version: 2.0
Catalog #

Catalog: NCC Cancer Therapeutic - Aug 2020 - Singapore Product Literature

Brochure: Drinking Water Testing Product Literature

User Guide: GeneBLAzer AVPR2 CHO-K1 DA and AVPR2‑CRE-bla CHO‑K1 Cell–Based Assay Manual / Product Insert

  • Version: 2.0
Catalog #

User Guide: GeneBLAzer FXR HEK 293T DA and FXR-UAS-bla HEK 293T Cell-based Assay Manual / Product Insert

  • Version: A.0
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