Antibiotics Background

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Key Antibiotics
G418 sulfateG418 sulfate (G418)
G418 sulfate (G418) is an aminoglycoside related to gentamycin that inhibits prokaryotic and eukaryotic protein synthesis. Toxic to bacteria, yeast, protozoans, helminths, higher plant, and mammalian cells, G418 is widely used in the selection of eukaryotic expression vectors carrying the bacterial neor/kanrgenes.
Hygromycin BHygromycin B
Hygromycin B displays broad spectrum activity against prokaryotes and eukaryotes by strongly inhibiting protein synthesis.
Neomycin Sulfate
An aminoglycoside, neomycin inhibits protein synthesis by binding to the ribosome, interfering with translation intitiation, inducing misreading, and promoting breakup of ribosomal polysomes.
Below are highlights and summaries from the Essential Biochemicals for Research, which is a technical resource and product guide for scientists for the preparation and use of biochemicals such as antibiotics, buffers, detergents, dyes, stains, and substrates, which are indispensable for any life science research laboratory. To view the full content, please download or request a print copy of this resource.

Preparing antibiotics before application

Antibiotic solutions are often sterile filtered before use so as to minimize the introduction of mycoplasma or other contaminants that can have a negative effect on the experiment. Use of Millex® filters and membranes prior to application removes potential contaminants and provides greater peace of mind.
  • Find the Millex® Syringe Filter that you need – Click Here.

Antibiotic Action on Bacteria

Many metabolic activities of the bacterial cell differ from those in mammalian cells. These differences can be exploited in the development of antibiotic agents. Antibiotics can either kill the bacteria (bactericidal) or prevent their growth (bacteriostatic). Antibiotics act on bacteria in one of the following ways:
A. Inhibition of cell wall synthesis
B. Inhibition of protein synthesis
C. Inhibition of nucleic acid synthesis
D. Anti-metabolic activity or competitive antagonism

Importance of the “kill curve” for Generation of Stably Transfected Mammalian Cell Lines

Different cell lines exhibit different sensitivities to antibiotics. Using an antibiotic concentration that is too high may result in nonspecific cytotoxicity, potentially killing desirably transfected cells. Using an antibiotic concentration that is too low may result in cells being exposed to selective media for too long; the longer cells are exposed to antibiotics, the more likely that resistant populations will emerge that may not contain the gene of interest. Therefore, prior to transfection, it is important to determine the antibiotic concentration that effectively kills untransfected cells (“kill curve”).