The maintenance of stock strains of trichomonads by freezing
| Autor: | M. G. McEntegart |
|---|---|
| Rok vydání: | 1954 |
| Předmět: | |
| Zdroj: | Epidemiology and Infection. 52:545-550 |
| ISSN: | 1469-4409 0950-2688 |
| DOI: | 10.1017/s0022172400037037 |
| Popis: | One of the difficulties of studying protozoa in vitro is the maintenance of stock strains. Unlike bacteria and viruses most protozoa cannot simply be put aside at room temperature or in a refrigerator until next required. If cultures are to be kept in a sound healthy condition they require frequent passage, generally at intervals of a few days. Clearly, if several strains are being employed this calls for the expenditure of a great deal of time and material. The isolation of protozoa in bacteria-free culture has been greatly simplified by the antibiotics, but is still far from easy. It is, in fact, sufficiently troublesome to make it worth while keeping in continuous passage every bacteria-free strain isolated even though it is of no immediate value to the investigation in progress. Quite apart from the time and material involved, frequent passage in vitro may lead to degradation of the strain until it bears little resemblance to a freshly isolated one. It was with a view to overcoming these difficulties that this study was undertaken. Weinman & McAllister in 1947 demonstrated that a number of pathogenic protozoa would survive freezing and thawing and could be stored in the frozen state without deteriorating; amongst those successfully preserved were trypanosomes, leishmania and plasmodia. The observations of these workers on trichomonads were limited to two species, Trichomonas vaginalis and T. hominis, both cultivated with bacteria. Of these T. vaginalis failed to survive at all and T. hominis was preserved in a proportion of experiments only. No successful results were recorded with ciliates or with Entamoeba histolytica. Recent work has shown that glycerol will protect a variety of living cells against injury during freezing and thawing (Smith, 1954). In 1953 Fulton and Smith were able to demonstrate for the first time that E. histolytica could be maintained at 79? C. as a result of the protective action of glycerol. Unfortunately glycerol may be injurious to the amoeba and it is probable that the ideal conditions for long-term storage of this parasite have yet to be discovered. These observations of Fulton & Smith were encouraging and it seemed possible that, by making use of glycerol, trichomonads also might be maintained frozen for useful periods. |
| Databáze: | OpenAIRE |
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