Poor quality of oocytes from Xenopus laevis used in laboratory experiments: prevention by use of antiseptic surgical technique and antibiotic supplementation.
OBJECTIVE
Episodic phases of continuous poor-quality oocytes obtained from South American Clawed Frogs (Xenopus laevis) often are observed. In publications dealing with the surgical technique of oocyte removal, the frogs' robust constitution and resistance against infections provided by magainins are pointed out. For this reason, clean rather than sterile conditions for the surgical procedure are mostly recommended. However, in most instances, antibiotics are added to the buffer medium when in vitro experiments are performed using oocytes.


METHODS
After a long phase of poor oocyte quality at our facility, involving oocytes that had been obtained by use of a "clean" surgical procedure, we subsequently cultured oocytes in a buffer medium containing the three antibiotics: penicillin G, gentamicin, and streptomycin.


RESULTS
During DNA injection experiments, the oocytes developed black spots on their surface by postoperative day two. Pure culture of the gram-negative non-fermentative rod Pseudomonas fluorescens was obtained from the impaired oocytes; the isolate was resistant to the three antibiotics. By contrast, after aseptic surgical removal and culture of oocytes in buffer medium containing the antibiotics tetracycline and gentamicin, perfect oocytes without bacterial contamination were obtained.


CONCLUSIONS
Whenever impaired oocyte quality is observed, microbial contamination should be considered as a possible cause.
Elsner
H A
HA
Department of Transfusion Medicine, Hannover Medical School, Germany.
Hönck
H H
HH
Willmann
F
F
Kreienkamp
H J
HJ
Iglauer
F
F
D000818:Animals; D000985:Antisepsis / Q000379:methods*; D001207:Asepsis / Q000379:methods*; D002478:Cells, Cultured; D003584:Cytological Techniques; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial; D013502:General Surgery / Q000379:methods; D005839:Gentamicins / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009865:Oocytes / Q000166:cytology* / Q000382:microbiology*; D010052:Ovariectomy / Q000379:methods* / Q000592:standards; D010400:Penicillin G / Q000494:pharmacology; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000302:isolation & purification*; D012867:Skin / Q000382:microbiology; D013307:Streptomycin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D020858:Tissue and Organ Harvesting / Q000379:methods* / Q000592:standards; D014982:Xenopus laevis
D005839:Gentamicins; D013752:Tetracycline; D010400:Penicillin G; D013307:Streptomycin