resulted in its expanded spectrum of activity and decreased susceptibility to the development of resistance when compared with other tetracycline antibiotics. Like minocycline, tigecycline binds to the bacterial 30S ribosome, blocking the entry of transfer RNA. This ultimately prevents protein synthesis and thus inhibiting bacterial growth. However, the addition of an N,N,-dimethylglycylamido group at the 9 position of the minocycline molecule increases the affinity of tigecycline for the ribosomal target up to 5 times when compared with minocycline or tetracycline. This allows for an expanded spectrum of activity and decreased susceptibility to the development of resistance. While tigecycline was the first tetracycline approved in over 20 years, other, newer versions of tetracyclines are currently in human clinical trials. List of tetracycline antibiotics Use as research reagents Members of the tetracycline class of antibiotics are often used as research reagents in in vitro and in vivo biomedical research experiments involving bacteria as well in experiments in eukaryotic cells and organisms with inducible protein expression systems using tetracycline-controlled transcriptional activation. The mechanism of action for the antibacterial effect of tetracyclines relies on disrupting protein translation in bacteria, thereby damaging the ability of microbes to grow and repair; however protein translation is also disrupted in eukaryotic mitochondria leading to effects that may confound experimental results. It can be used as an artificial biomarker in wildlife to check if wild animals are consuming a bait that contains a vaccine or medication. Since it is fluorescent and binds to calcium, a UV lamp can be used to check if it is in a tooth pulled from an animal. For example, it was used to check uptake of oral rabies vaccine baits by raccoons in the USA. However, this is an invasive procedure for the animal and labour-intensive for the researcher. Therefore, other dyes such as rhodamine B that can be detected in hair and whiskers are preferred. See also Glycylcycline Eravacycline Tetracycline controlled transcriptional activation Animal Drug Availability Act 1996 References External links Hepatotoxins