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Cryptocaryon irritans is a highly detrimental parasite in mariculture, causing significant economic losses to the aquaculture industry of Larimichthys crocea. In recent years, copper and copper alloy materials have been used to kill parasites. In this study, the effect of copper plates on the tomont period of C. irritans was explored. The findings indicated that copper plates effectively eradicated tomonts, resulting in a hatching rate of 0. The metabolomic analysis revealed that a total of 2,663 differentially expressed metabolites (1,032 up-regulated and 1,631 downregulated) were screened in the positive ion mode, and 2,199 differentially expressed metabolites (840 up-regulated and 1,359 down-regulated) were screened in the negative ion mode. L-arginine and L-aspartic acid could be used as potential biomarkers. Copper plate treatment affected 25 metabolic pathways in the tomont, most notably influencing histidine metabolism, retinol metabolism, the biosynthesis of phenylalanine, tyrosine, and tryptophan, as well as arginine and proline metabolism. It was shown that high concentrations of copper ions caused a certain degree of disruption to the metabolome of tomonts in C. irritans, thereby impacting their metabolic processes. Consequently, this disturbance ultimately leads to the rapid demise of tomonts upon exposure to copper plates. The metabolomic changes observed in this study elucidate the lethal impact of copper on C. irritans tomonts, providing valuable reference data for the prevention and control of C. irritans in aquaculture. [ABSTRACT FROM AUTHOR]

Ichthyophthirius multifiliis is a pathogenic ciliate parasite, which infects almost all freshwater teleost fish and leads to significant economic losses. The present study aimed to evaluate the acute toxicity of berberine to the free-living stages of I. multifiliis, that is, theronts and tomonts. Our results indicated that 99.30% of I. multifiliis theronts were killed by a concentration of 15 mg/L berberine during the 4 h exposure time, while berberine had no effect on protomonts. Nevertheless, berberine at a concentration of 5 mg/L could effectively reduce the release of theronts from tomonts treated for 4 h. Additionally, according to the transmission electron microscopy results, berberine at 15 mg/L could strongly change the shape of protomonts, destroy their organelles, and significantly decrease the number of ribosomes. The median lethal concentration (LC50) of berberine for goldfish at 96 h was 528.44 mg/L, which was almost 67 times the median effective concentration (EC50) of berberine for killing theronts (7.86 mg/L). The results demonstrated that berberine could be an effective and safe potential parasiticide for killing I. multifiliis. [ABSTRACT FROM AUTHOR]

Ichthyophthirius multifiliis is a pathogenic ciliate parasite, which infects almost all freshwater teleost fish and leads to significant economic losses. The present study aimed to evaluate the acute toxicity of berberine to the free-living stages of I. multifiliis, that is, theronts and tomonts. Our results indicated that 99.30% of I. multifiliis theronts were killed by a concentration of 15 mg/L berberine during the 4 h exposure time, while berberine had no effect on protomonts. Nevertheless, berberine at a concentration of 5 mg/L could effectively reduce the release of theronts from tomonts treated for 4 h. Additionally, according to the transmission electron microscopy results, berberine at 15 mg/L could strongly change the shape of protomonts, destroy their organelles, and significantly decrease the number of ribosomes. The median lethal concentration (LC50) of berberine for goldfish at 96 h was 528.44 mg/L, which was almost 67 times the median effective concentration (EC50) of berberine for killing theronts (7.86 mg/L). The results demonstrated that berberine could be an effective and safe potential parasiticide for killing I. multifiliis.

Cryptocaryon irritans is a highly detrimental parasite in mariculture, causing significant economic losses to the aquaculture industry of Larimichthys crocea . In recent years, copper and copper alloy materials have been used to kill parasites. In this study, the effect of copper plates on the tomont period of C. irritans was explored. The findings indicated that copper plates effectively eradicated tomonts, resulting in a hatching rate of 0. The metabolomic analysis revealed that a total of 2,663 differentially expressed metabolites (1,032 up-regulated and 1,631 down-regulated) were screened in the positive ion mode, and 2,199 differentially expressed metabolites (840 up-regulated and 1,359 down-regulated) were screened in the negative ion mode. L-arginine and L-aspartic acid could be used as potential biomarkers. Copper plate treatment affected 25 metabolic pathways in the tomont, most notably influencing histidine metabolism, retinol metabolism, the biosynthesis of phenylalanine, tyrosine, and tryptophan, as well as arginine and proline metabolism. It was shown that high concentrations of copper ions caused a certain degree of disruption to the metabolome of tomonts in C. irritans , thereby impacting their metabolic processes. Consequently, this disturbance ultimately leads to the rapid demise of tomonts upon exposure to copper plates. The metabolomic changes observed in this study elucidate the lethal impact of copper on C. irritans tomonts, providing valuable reference data for the prevention and control of C. irritans in aquaculture., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Guo, Huang, Xu, Zhan, Sun and Hu.)

Cryptocaryoniasis is a severe parasitic disease caused by ciliate Cryptocaryon irritans in farmed marine fish. To control this disease, we established a method to interrupt the life cycle of C. irritans via the removal of its tomonts. Marine fish Plectorhinchus cinctus were divided randomly into four groups, including placemat removal group (Group I), rotational culturing group (Group II), infection control group (IF group) and blank control group (Control); the former three groups were infected with C. irritans at low dose. A daily food consumption (DFC), relative infection intensity (RII) and survival rate of each group were observed. At 4-week post infection, some fish were challenged with C. irritans theronts at a lethal dose. Results showed that the fish' DFC in IF Group, Group I and II decreased significantly on 2nd day post infection, and gradually restored food intake when the trophonts exited the fish on the 5th day. However, their DFC in IF Group decreased significantly on 7th day, and eventually stopped feeding. Trophonts on fish' body of the three groups began to reduce from the 4th day and those of Group I and II almost disappeared on the 7th day, conversely the trophonts of IF group increased ten times. At 2-week post infection, the survival rates of Group I, II, IF and Control were 97%, 98%, 0%, and 100%, respectively. The survival rates of Group I, II and Control were 88.3%, 93.3%, 66.7%, respectively after challenge. Results demonstrate that placemat and rotational culturing method to remove tomonts can effectively control C. irritans infection. Statement of relevance Cryptocaryoniasis is a severe parasitic disease caused by ciliate Cryptocaryon irritans in farmed marine fish. To control this disease, we established a method to interrupt the life cycle of C. irritans via the removal of its tomonts. Marine fish P. cinctus were divided randomly into four groups, including placemat removal group (Group I), rotational culturing group (Group II), infection control group (IF group) and blank control group (Control); the former three groups were infected with C. irritans at low dose. A daily food consumption (DFC), relative infection intensity (RII) and survival rate of each group were observed. At 4-week post infection, some fish were challenged with C. irritans theronts at a lethal dose. Results showed that the fish' DFC in IF Group, Group I and II decreased significantly on 2nd day post infection, and gradually restored food intake when the trophonts exited the fish on the 5th day. However, their DFC in IF Group decreased significantly on 7th day, and eventually stopped feeding. Trophonts on fish' body of the three groups began to reduce from the 4th day and those of Group I and II almost disappeared on the 7th day, conversely the trophonts of IF group increased ten times. At 2-week post infection, the survival rates of Group I, II, IF and Control were 97%, 98%, 0%, and 100%, respectively. The survival rates of Group I, II and Control were 88.3%, 93.3%, 66.7%, respectively after challenge. Results demonstrate that placemat and rotational culturing method to remove tomonts can effectively control C. irritans infection. This method is an mechanical preventive one, not only provides an ideal means for controlling C. irritans in small scale culture systems, but also solves food safety problems. [ABSTRACT FROM AUTHOR]

The ectoparasite protozoan Amyloodinium ocellatum (AO) is the etiological agent of amyloodiniosis in European seabass (Dicentrarchus labrax) (ESB). There is a lack of information about basic molecular data on AO biology and its interaction with the host. Therefore, de novo transcriptome sequencing of AO tomonts was performed. AO trophonts were detached from infested ESB gills, and quickly becoming early tomonts were purified by Percoll® density gradient. Tomont total RNA was processed and quality was assessed immediately. cDNA libraries were constructed using TruSeq® Stranded mRNA kit and sequenced using Illumina sequencer. CLC assembly was used to generate the Transcriptome assembly of AO tomonts. Out of 48,188 contigs, 56.12% belong to dinophyceae wherein Symbiodinium microadriaticum had 94.61% similarity among dinophyceae. Functional annotations of contigs indicated that 12,677 had associated GO term, 9005 with KEGG term. The contigs belonging to dinophyceae resulted in the detection of several peptidases. A BLAST search for known virulent factors from the virulence database resulted in hits to Rab proteins, AP120, Ribosomal phosphoprotein, Heat-shock protein70, Casein kinases, Plasmepsin IV, and Brucipain. Hsp70 and casein kinase II alpha were characterized in-silico. Altogether, these results provide a reference database in understanding AO molecular biology, aiding to the development of novel diagnostics and future vaccines. [ABSTRACT FROM AUTHOR]