title: LOCALIZATION OF OXYTETRACYCLINE IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE)(1).
abstract: Oxytetracycline (OTC) is an important antimicrobial used in aquaculture. However, residues of OTC have been isolated from nontarget aquatic organisms, sediments, and water located near aquaculture facilities. Identifying OTC in plant material is particularly difficult due to interference from pigments and polyphenol substances but is important especially for algae since they are a primary food source for fish in early life stages. In this study, we describe the effect of OTC (0.1, 1, 10, 25, 50, 100 μg · mL(-1) ) on cell growth, and the localization of OTC (0, 1, 25, 100 μg · mL(-1) ) in vacuoles of Chlamydomonas reinhardtii P. A. Dang. (wildtype, ATCC 18798). We also present a method for semiquantifying OTC in living cells using fluorescent microscopy and Adobe Photoshop. We exposed algal cells to OTC and sampled after 2 or 7 d exposure. On day 7, OTC significantly inhibited algal growth at 1, 10, 25, 50, and 100 μg · mL(-1) . When viewed with fluorescent microscopy, cells exposed to the 25 and 100 μg · mL(-1) contained yellow fluorescent areas, ≤1 μm in diameter that were easily discernable against the red fluorescence of the intracellular chl. The fluorescent areas corresponded to small spherical vacuoles (i.e., polyphosphate bodies that contain calcium and magnesium complexed with polyphosphate) seen in the cells by LM. Since OTC has a high affinity for divalent cations, we suggest that OTC is localized in these vacuoles.
authors.affiliation: Marine Estuarine Environmental Sciences Program, University of Maryland Baltimore, Baltimore, Maryland 21201, USA Aquatic Pathobiology Center, VA-MD Regional College of Veterinary Medicine, Maryland Campus, 8075 Greenmead Drive, College Park, Maryland 20742, USAEmerging Pathogens Institute, PO Box 100009, University of Florida, Gainesville, Florida 32610-0009, USACenter for Veterinary Medicine, FDA, 7500 Standish Place, Rockville, Maryland 20855, USACenter for Veterinary Medicine, FDA, 8401 Muirkirk Road, Laurel, Maryland 20708, USA.
authors.forename: Roberta J
authors.initials: RJ
authors.lastname: Garcia
authors.affiliation: Marine Estuarine Environmental Sciences Program, University of Maryland Baltimore, Baltimore, Maryland 21201, USA Aquatic Pathobiology Center, VA-MD Regional College of Veterinary Medicine, Maryland Campus, 8075 Greenmead Drive, College Park, Maryland 20742, USAEmerging Pathogens Institute, PO Box 100009, University of Florida, Gainesville, Florida 32610-0009, USACenter for Veterinary Medicine, FDA, 7500 Standish Place, Rockville, Maryland 20855, USACenter for Veterinary Medicine, FDA, 8401 Muirkirk Road, Laurel, Maryland 20708, USA.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Kane
authors.affiliation: Marine Estuarine Environmental Sciences Program, University of Maryland Baltimore, Baltimore, Maryland 21201, USA Aquatic Pathobiology Center, VA-MD Regional College of Veterinary Medicine, Maryland Campus, 8075 Greenmead Drive, College Park, Maryland 20742, USAEmerging Pathogens Institute, PO Box 100009, University of Florida, Gainesville, Florida 32610-0009, USACenter for Veterinary Medicine, FDA, 7500 Standish Place, Rockville, Maryland 20855, USACenter for Veterinary Medicine, FDA, 8401 Muirkirk Road, Laurel, Maryland 20708, USA.
authors.forename: David
authors.initials: D
authors.lastname: Petullo
authors.affiliation: Marine Estuarine Environmental Sciences Program, University of Maryland Baltimore, Baltimore, Maryland 21201, USA Aquatic Pathobiology Center, VA-MD Regional College of Veterinary Medicine, Maryland Campus, 8075 Greenmead Drive, College Park, Maryland 20742, USAEmerging Pathogens Institute, PO Box 100009, University of Florida, Gainesville, Florida 32610-0009, USACenter for Veterinary Medicine, FDA, 7500 Standish Place, Rockville, Maryland 20855, USACenter for Veterinary Medicine, FDA, 8401 Muirkirk Road, Laurel, Maryland 20708, USA.
authors.forename: Renate
authors.initials: R
authors.lastname: Reimschuessel
keywords: Chlamydomonas reinhardtii; oxytetracycline; vacuoles