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

Abstract

BackgroundCryptocaryon irritans, a species of obligatory ciliate ectoparasite, can infect various species of marine teleost fish. Cryptocaryon irritans that fall to the seabed or aquarium bottom in winter can form “dormant tomonts” and wake up when the temperature rises the next year. Abundant studies and analyses on the dormant tomonts were carried out at the transcriptome level, in order to investigate the molecular mechanism of C. irritans tomonts entering the dormant state under low-temperature conditions.MethodsThe paired-end sequencing strategy was used to better assemble the entire transcriptome de novo. All clean sequencing reads from each of the three libraries (Group A: untreated blank control; Group B: treated for 24 h at 12 °C; and Group C: developed for 24 h at 25 °C) were respectively mapped back to the transcriptome assembly using the bioinformatics software.ResultsIn this study, 25,695,034, 21,944,467, and 28,722,875 paired-end clean reads were obtained respectively from the three cDNA libraries of the C. irritans tomont by Illumina paired-end sequencing technology. A total of 25,925 unique transcript fragments (unigenes) were assembled, with an average length of 839 bp. Differentially expressed genes (DEGs) were scrutinized; in Group B/A pairwise comparison, 343 genes presented differential expression, including 265 up-regulated genes and 78 down-regulated genes in Group B; in Group C/A pairwise comparison, there were 567 DEGs, including 548 up-regulated genes and 19 down-regulated genes in Group C; and in Group B/C pairwise comparison, 185 genes showed differential expression, including 145 up-regulated genes and 40 down-regulated genes in Group B.ConclusionsThis is the first transcriptomic analytical study of the C. irritans tomonts under low temperature. It can be concluded that most of the genes required for its cell survival under low temperature, or for cell entry into a deeper dormancy state were discovered, and that they might be considered as candidate genes to develop the diagnostic and control measures for cryptocaryoniasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1550-1) contains supplementary material, which is available to authorized users.

Transcriptome Analysis Based on RNA-Seq in Understanding Pathogenic Mechanisms of Diseases and the Immune System of Fish: A Comprehensive Review

“…Being qualitative as well as quantitative, this technology has led to the identification of many molecular actors and their patterns of expression in a limited time-frame, laying the foundation for further studies in the mechanisms of host–pathogen interaction. This technology has also aided in testing the efficacy of vaccines [ 41 , 44 , 74 ], treatment options [ 107 , 114 ], immunostimulants [ 150 ], and immunoprotective diets [ 36 ] against pathogens. Transcriptome data derived during host–pathogen interactions will be useful to understand virulence genes of the pathogens that are induced in vivo.…”

“…The analysis of the tomont stage of C. irritans under low temperature helped in the identification of several genes required for the parasitic stage to enter a deeper dormancy state and survive low temperatures. These genes might be considered as potential candidate genes to develop diagnostic and control measures for cryptocaryoniasis [ 114 ]. Similarly, 9 putative immobilization antigens transcripts and 161 protease transcripts were found in the transcriptome of C. irritans which could be considered as major targets for vaccines and drug development, respectively [ 115 ].…”

A new age in AquaMedicine: unconventional approach in studying aquatic diseases

“…Among the isolation were proteins of the cytoskeletal apparatus (β-tubulin and actin), as well as the enzyme enolase and the heat shock protein hsp70 [ 93 ]. Moreover, Yin et al [ 94 ] conducted an analysis of the transcriptomes of trophont, either untreated or treated at either 12 or 25 °C. The authors described up-regulation of several genes required for the cell’s survival at lower temperature and entry into dormancy [ 94 ].…”

“…Moreover, Yin et al [ 94 ] conducted an analysis of the transcriptomes of trophont, either untreated or treated at either 12 or 25 °C. The authors described up-regulation of several genes required for the cell’s survival at lower temperature and entry into dormancy [ 94 ].…”

Molecular mechanisms of an antimicrobial peptide piscidin (Lc-pis) in a parasitic protozoan, Cryptocaryon irritans

“…It has been broadly applied in studies of the molecular mechanisms including stress resistance, models of development and the immune defenses [20, 21]. Transcriptomic analyses of C. irritans have been conducted on different developmental stages and transformations after low temperature treatments [22–25]. We analyzed transcriptome variances among different developmental stages and compared the changes in transcriptomes after treated by Lc-pis.…”