Dynamics and distribution properties of theronts of the parasitic ciliate Cryptocaryon irritans

Transcriptome analysis of dormant tomonts of the marine fish ectoparasitic ciliate Cryptocaryon irritans under low temperature

“…In recent years, this parasitic disease has often occurred in China’s coastal provinces and cities, bringing great losses to the fish farmers and relevant departments. In order to explore the pathogenesis of and effective control measures for C. irritans , researchers have carried out extensive studies from variable perspectives [ 1 – 3 ]. The regularity of parasite occurrence suggests that outbreaks of this disease are related to water temperature [ 4 ].…”

Control of the Daily Rhythms by Photoperiods in Protomont Detachment and Theront Excystment of the Parasitic Ciliate <i>Cryptocaryon irritans</i>

“…Most of C. irritans experimental propagation was previously carried out from late at night to early in the morning because important events (protomont detachment and theront excystment) occur during this period (Burgess and Matthews, 1994;Yoshinaga and Dickerson, 1994;How et al, 2015). Long and unconventional hours were required to work on this parasite.…”

“…The life cycle of C. irritans consists of four developmental stages; namely, theront (invasive free-swimming stage), trophont (parasitic stage harboring host epithelial tissues), protomont (stage just after being detached from hosts after full development), and tomont (cystic stage producing and releasing theronts) (Sikama, 1937;Brown, 1963;Colorni, 1985).Cryptocaryon irritans is typically propagated by exposing (or passaging) the parasite on live fish (Colorni, 1985;Burgess and Matthews, 1994;Yoshinaga and Dickerson, 1994;Dan et al, 2006), because in vitro culture methods for their propagation are not available, although the trophonts of this parasite can be grown in vitro, to a certain extent (Yoshinaga et al, 2007). The serial passaging of the parasite on fish is laborious, especially because important events of the parasite (detachment of trophonts from hosts and excystment of theronts from tomonts) occur from late at night to early in the morning (Yoshinaga and Dickerson, 1994;Burgess and Matthews, 1994;How et al, 2015). Furthermore, the passaging on fish must be repeated at almost oneweek intervals, without interruption.…”

Infectivity and genes differentially expressed between young and aging theront cells of the marine fish parasite Cryptocaryon irritans

“…The limited-energy-supplies assumption is supported by observations made by Yoshinaga and Dickerson [ 29 ], who showed that 81% of theronts lost mobility as early as 8.5 hrs post-excystment. A recent study that quantitatively described theront movements also showed a much narrower range of movements in theronts collected 12 hrs post excystment [ 44 ]. Our RNA-seq results seem to corroborate with these physiological observations: many genes involved in ATP-producing processes are significantly downregulated in aging theronts ( Fig 5 and Table 3 ).…”