- Does R&D Systems® hyaluronan contain any chondroitin sulfate?
- No, the hyaluronan is produced by microbial fermentation of Streptococcus pyogenes, which does not make chondroitin sulfate.
- The serum from which animal species is recommended as a blocking reagent for IHC and ICC staining?
- 10% Donkey serum works well generally as a blocking reagent. Serum from the same species as the secondary antibody could alternatively be used as a blocking reagent.
- What is R&D Systems doing to reduce its use of packaging from non-renewable resources?
- Environmental stewardship is important to R&D Systems and its employees. R&D Systems is ISO 14001:2015 Certified and as part of this we are continuously reviewing our sustainability practices and "green" options. First and foremost, the energy expended to ship back the styrofoam box is more detrimental to the environment than having the facility re-use or recycle it. Our stance is to encourage our customers to implement a recycling program locally. At R&D Systems we have chosen to reduce the use of styrofoam as much as possible by: doing extensive stability testing in order to determine which products can be shipped with minimal packaging at ambient temperatures, converting the use of non-recyclable packaging materials to recyclable plastics, cardboard, or biodegradable materials, and continuing to investigate alternatives to dry ice shipments, the use of re-usable containers, and gel packs that allow for smaller styrofoam containers. Employees were key to initiating a recycling program at our facilities. Internally, we recycle paper, plastic, cardboard, aluminum, and glass.
General Laboratory Reagents
- Why do some cell culture media contain Sodium Pyruvate?
- Sodium pyruvate is added to many low glucose and high glucose DMEM formulations. Sodium pyruvate can be used by cells as a readily accessible carbon source for energy production and other critical metabolic pathways, bypassing the need to produce it biosynthetically from glucose or amino acids. Some cell lines require the addition of pyruvate to the culture media since they lack the ability to convert glucose or amino acids into pyruvate.
- Why is HEPES used in cell culture?
- HEPES (N-2-hydroxyethylpiperazine-N’-2-ethanesulfonic acid, pKa@37oC=7.3, useful range pH 6.6 – 8.0) is one of several biological buffers that can be used to stabilize the pH of cell culture medium. As cells grow and metabolize the cell culture medium nutrients, they typically produce excess acid – that lowers the pH of the medium. This lowering of pH can be detrimental to the continued growth of cells in culture. HEPES provides more “buffering” capacity than the bicarbonate normally found in cell culture medium – thus slowing the decline in pH as cells metabolize the nutrient medium. For some cell lines this extends the time between “feedings” and promotes healthier cell growth. HEPES can show toxicity with some cell lines, so it is not a universal panacea. Other useful biological buffers include MOPS (pKa@37oC=7.0), TRIS (pKa@37oC=7.8), and PIPES (pKa@37oC=6.7).