Coelenterazines are predominantly yellow solids, but may contain dark red or brown flecks. This does not affect product stability or performance. If your coelenterazine is uniformly brown, then it is oxidized and needs to be replaced.
Most of our products are stable at room temperature for many days, but we recommend storage at 4°C or -20°C to prolong shelf life. In the case of many of our aqueous dye solutions, the compounds are very stable at room temperature, but we recommend cold storage to prevent the growth of mold or other microbes over time. Therefore, to save on shipping costs, products with recommended storage at 4°C or -20°C may ship at ambient temperature or with an ice pack. These products may thaw without affecting product performance. When you receive the product, place it under the recommended storage conditions.
Most of our products are stable at room temperature for many days, so in all likelihood the product will still work just fine. To be on the safe side, we recommend performing a small scale positive control experiment to confirm that the product still works for your application before processing a large number of samples or precious samples.
One exception that we are aware of is GelGreen™, which is more sensitive to light exposure than most of our other fluorescent dyes. If GelGreen™ is exposed to ambient light for a prolonged period of time (days to weeks), its color will change from dark orange to brick red. If this occurs, the GelGreen will no longer work for gel staining.
The Yeast Viability Staining Kit is a fluorescent assay to determine yeast viability. Each kit contains two fluorescent components: CF® Dye-labeled Concanavalin A (Con A) and Live-or-Dye™ viability dye. We offer 3 different color combinations to choose from.
When both dyes are used to stain yeast, live cells display bright fluorescent cell wall staining (Con A), while dead cells with compromised membrane activity exhibit both cell wall staining and cytoplasmic staining (Live-or-Dye™). The dye labeling is extremely stable, allowing the cells to be fixed and permeabilized without loss of fluorescence or dye transfer between cells.
Live-or-Dye™ viability dyes are cell membrane impermeable amine-reactive dyes designed for discrimination between live and dead cells during flow cytometry or microscopy. They are able to enter into dead cells that have compromised membrane integrity and covalently label free amines on intracellular proteins.
Concanavalin A (Con A) is a widely used lectin that selectively binds to α-mannopyranosyl and α-glucopyranosy residues, found in the cell wall of yeast and fungi. It is labeled with one of our superior bright and photostable CF® dyes.