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Korean J Parasitol > Volume 8(2):1970 > Article

Original Article
Korean J Parasitol. 1970 Aug;8(2):39-47. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1970.8.2.39
Copyright © 1970 by The Korean Society for Parasitology
Study on Metagonimus yokogawai (katsurada, 1912) in Korea II. The in vitro excystation of metacercariae
Kon Sik Kim and Byongl Seol Seo
Department of Parasitology and Institute of Endemic Diseases, College of Medicine, Seoul National University, Korea.
Abstract

A series of experiments on various factors which induce optimal in vitro excystation of the metacercariae of Metagonimus yokogawai isolated from the fish, Plecoglossus altivelis was conducted and the following results were obtained.

1) The metacercariae used in this experiment were isolated by the digestion technique therefore all of them were pretreated with the acid-pepsin solution before being applied to the various tests.

2) No excystation occurred when the metacercariae were placed in a salt solutions such as physiological saline, Tyrode solution and Veronal, Tris buffers alone or in combination.

3) The metacercariae underwent complete excystation in the trypsin and pancreatin solution in Tris buffer within an hour at 38℃. The best results were obtained in 0.8-0.9% trypsin solutions, pH 8.0-8.6 and at 38-40℃, approximately one hundred per cent excystation occurred in 40 minutes. Not only temperature but also hydrogen ion concentration played an important role causing excystation of the metacercariae in trypsin-Tris buffer solution. However, bile salts were not responsible for the excystation.

4) Agitation effect on the excystation was tested as a mechanical stimulus and it was found that the shaking stimulus accelerated the excysting mechanism, compared with the metacercariae on which it was not imposed.

It is concluded that the metacercariae pretreated in the acid pepsin solution demonstrates an essential requirement for the enzyme solution such as trypsin or pancreatin, provided with the optimum conditions of temperature and hydrogen ion concentration in excysting medium.

Figures


Fig. 1
Excystation of Metagonimus yokogawai metacercariae in 1.0% trypsin and pancreatin in 0.05M Tris buffer at 37℃.


Fig. 2
The effect of various concentrations of trypsin Tyrode solution on excystation of Metagonimus yokogawai metacercariae at 37℃.


Fig. 3
The effect of temperature on excystation of Metagonimus yokogawai metacercariae in 0.8% trypsin 0.05M Tris buffer, pH 8.6.


Fig. 4
The effect of pH on excystation of Metagonimus yokogawai metacercariae in 0.8% trypsin in Tris buffer. Results read after 20 minutes incubation at 38℃.

Tables


Table 1
Effect of various concentrations of trypsin Tyrode solution on the excystation of Metagonimus yokogawai metacercariae at 37℃


Table 2
Effect of Temperature on excystation of Metagonimus yokogawai metacercariae in 0.8% Trypsin-0.05M Tris buffer (pH 8.6)


Table 3
Effect of hydrogen ion concentration upon excystation of Metagonimus yokogawai metacercariae in 0.8% Trypsin-Tris or Veronal buffer at 38℃


Table 4
Effect of Agitation of Metagonimus yokogawai metacercariae in Dubnoff metabolic shaker at RPM 60 in 0.8% trypsin Tris buffer (pH 8.6) and in 0.65% physiological salt solution at 38℃

References
1. Hunter WS, et al. J Parasit 1952;38:87.
 
2. Kobayashi A, et al. Acta Scholae Medicinalis in Gifu 1959;7:822–827.
3. Oshima T. Jpn J Parasit 1956;5:84–95.
4. Oshima T, et al. Jpn J Parasit 1958;7:73.
5. Seo BS. New Med J 1959;2:65–73.
6. Seo BS, Yoon JS, Lee CW, Lee SH. [Studies On Microphalloides Japonicus]. Korean J Parasitol 1964;2(1):41–51.
 
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