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Zoological Science
Abstract
The infection caused by a kinetoplastid flagellate, Azumiobodo hoyamushi, in an ascidian, Halocynthia roretzi, results in softening of the tunic, and finally death. This disease is usually recognized using palpation of the softening tunic, and A. hoyamushi infection is detectable using microscopy or PCR amplification of specific gene fragments. The present study is the first quantitative evaluation of the symptoms of soft tunic syndrome by measuring the amount of bending (bending) and the peak force required to pierce the tunic (force). There was a strong correlation between bending and force. Correlation analyses among other parameters (ascidian total weight, tunic thickness, and tunic water content) indicated that larger ascidians had harder and thicker tunics with a higher water content. As compared to the tunic of healthy individuals, softened tunic was thinner and had lower water content. Infected tunics thus possibly lose water and become softer and thinner. Mechanisms for maintaining the appropriate water level content may be crucial for preventing tunic softening.
This study was supported by KAKENHI (no. 15H05251) from the Japan Society for the Promotion of Science. We thank Ayaka Ozeki for helping the measurements of Ishinomaki specimens.
The authors have no competing interest to declare.
EH designed the study and prepared the manuscript. KN, TY, and SK contributed to measurement and analyses. AN prepared the animals. All authors gave final approval of the manuscript for publication.
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