Number Of Trophonts Research Articles

Malformed largemouth bass (Micropterus salmoides) are more susceptible and vulnerable to Ichthyophthirius multifiliis infections: Immunological and histopathological study

It is widely acknowledged that the malformed fish shows low resistance to diseases due to abnormal development of body, leading to the decrease of viability. Until now, there is no evidence for the relationship between developmental abnormalities and pathogen infections in fish breeding. In this study, the first record of Ichthyophthirius multifiliis infection in Micropterus salmoides was reported. Importantly, an interesting phenomenon that malformed fish suffered from more serious Ichthyophthiriasis than normal fish was demonstrated with the investigation of differences in the infection rate and the number of trophonts. Furthermore, the immune response, histopathological examination, and efficacy of antiparasitic drug against I. multifiliis infection were determined in normal and malformed fish. The fish affected by malformation resulted in decline of survival rate after infection with I. multifiliis at day 2 in comparison to the fish with normal development (p < 0.001). Malformation also caused significantly low expression of immune-related genes, including immunoglobulin (IgM), T cell receptor (TCR), pro-inflammatory cytokines (IL-10, IL-1β), cell mediated-immunity mediators (MHC-I), chemokine (CCL2), complement (C5), cluster of differentiation (CD4–1 and CD8-α), in skin, liver and spleen (p < 0.05). Also, histopathological examination showed distinct lesions in skin, gills, and fins of malformed fish. In addition, the survival rate of normal fish was significantly elevated after treatment with magnolol, an anti-parasitic drug, for 7 days compared to malformed fish (p < 0.001). Overall, these data indicate that weak immune response and more tissue damage in malformed fish might increase the susceptibility to pathogens, and the high mortality rate was associated with poor efficacy of magnolol in malformed fish. This study provides evidence for low resistance to pathogens and high mortality rate of fry caused by high malformation rate. Particularly, the malformed fish may act as a source of infection, spreading infectious disease for other healthy fish, causing mass economic losses for M. salmoides industry. Malformation is worth to pay more attention for fish breeding studies.

Copper alloy particles incorporated in coatings improve the surfaces of aquaculture tanks for controlling Cryptocaryon irritans infections

Previous studies have found that copper alloy sheets can kill the protozoan Cryptocaryon irritans effectively as the tomonts of this particular pathogen adhere to the hard surface of tanks. This study explored the potential use of copper alloy particles incorporated into coatings to be applied to the bottom of aquaculture tanks, in order to control cryptocaryoniasis outbreaks. Results showed that the number of trophonts on Trachinotus ovatus exposed to such copper coated surfaces was significantly lower than that in the control and blank groups 5 days later and effectively blocked the reinfection of C. irritans, thereby decreasing the mortality rate of T. ovatus. In in vitro assays, the mortality rate of protomonts and tomonts was up to 100% at 6th h and 24th h of post contacting with the copper coated surfaces, respectively. Safety assessments found that copper concentration was not significantly high in flowing seawater, but it showed an upward trend with longer immersion time, increasing significantly from 0.56 to 5.90 μg/L within a 30-day period. When exposed to the copper alloy coating, the bottom-crawling fish Epinephelus coioides, did not accumulate an excessive copper concentration in the serum, liver or muscle tissues. This study provides a safe and effective strategy to control cryptocaryoniasis in marine factory farming.

The effect of dietary immunostimulants on the susceptibility of common carp (Cyprinus carpio) to the white spot parasite, Ichthyophthirius multifiliis.

One of the main obstacles in freshwater aquaculture is the parasitic ciliate Ichthyophthirius multifiliis (Ich), the causative agent of white spot disease. The use of immunostimulants as feed additives may be a promising approach to control Ich infection. In the present study, we tested the prophylactic effect of orally administered β-1,3/1,6-glucan and propolis extract E50 against Ich infection in common carp. In total, 122 fish were separated into three experimental groups fed with a control, 3% β-glucan and 1% propolis diet for 40 consecutive days, respectively. On day 40, 16 fish per group were individually exposed to Ich theronts and the number of trophonts was counted 5 days post exposure. Relative gene expression of interleukin 1-β (IL-1-β) in common carp liver was examined by qPCR. Compared to control, the mean infection intensity was lower in the β-glucan- and propolis-fed groups; however, the difference was not statistically significant. The relative expression of IL-1-β significantly decreased in the propolis-fed group at day 10. In the β-glucan-fed group, a significant IL-1-β decrease was detected at day 15 compared to control. Although the Ich infection intensity was slightly decreased in both treated groups, and IL-1-β was moderately down-regulated in the liver of common carp, our results suggest that the applied feeding regime is insufficient to prevent Ich outbreaks in common carp.

Melaleuca alternifolia essential oil prevents oxidative stress and ameliorates the antioxidant system in the liver of silver catfish (Rhamdia quelen) naturally infected with Ichthyophthirius multifiliis

Oxidative stress has been linked to a pathological mechanism that contributes to the initiation and progression of hepatic injury during Ichthyophthirius multifiliis infection. Thus, natural compounds with antioxidant and free radical scavenger properties, such as the Melaleuca alternifolia essential oil (TTO), might help to prevent or reduce hepatic damage. Thus, the aim of this study was to investigate whether TTO is capable of preventing or reducing hepatic oxidative damage in silver catfish naturally infected with I. multifiliis. After a TTO bath treatment of 1h/day for 4days, the number of trophonts on the skin of catfish was reduced by 94.87% compared to the control group. Hepatic samples from fish infected by I. multifiliis showed increased thiobarbituric acid reactive substances (TBARS) and protein carbonylation levels, while catalase (CAT) activity decreased compared to uninfected and untreated animals. Moreover, the histopathology analyses demonstrated the presence of necrosis, nuclear lateralization and cariorrexis, as well as swelling and vacuolization of cytoplasm. Treatment with TTO reduced hepatic TBARS and protein carbonylation levels and ameliorated the antioxidant system of infected fish, as well as preserve the hepatocytes morphology, but not prevented the occurrence of necrosis. Based on our findings, we propose that TTO is an alternative therapeutic option for silver catfish infected with I. multifiliis. Moreover, TTO treatment is a useful approach for avoiding or minimizing the hepatic oxidative stress caused by I. multifiliis, thus improving the hepatic antioxidant system.

The Essential Oil of Hyptis mutabilis in Ichthyophthirius multifiliis Infection and its Effect on Hematological, Biochemical, and Immunological Parameters in Silver Catfish, Rhamdia quelen.

This study evaluated the activity of leaf essential oil (EO) from Hyptis mutabilis as well as its major constituent, (-)-globulol, in infections by the parasite Ichthyophthirius multifiliis (ich). Effects on hematological, biochemical, and immunological parameters of silver catfish, Rhamdia quelen, exposed to the same samples also were evaluated. In the first experiment, naturally infected fish were treated with EO (0, 10, and 20 mg · L-1) and ethanol, using several methods of exposure. Fish mortality and the number of trophonts per fish were assessed after 48 and 96 hr. Hour-long daily baths resulted in optimal survival, so this methodology was used for the second experiment, in which infected animals were exposed to (-)-globulol at 2.5 and 5 mg · L-1. The most effective concentrations in Experiments 1 and 2 were chosen for Experiment 3, in which healthy animals were subjected to hour-long daily baths with EO (20 mg · L-1) or (-)-globulol (2.5 mg · L-1). Additionally, an in vitro experiment was performed with EO and globulol at the same concentrations of the in vivo test. EO and (-)-globulol increased the survival of fish infected with ich and altered certain hematological and biochemical parameters. After 4 days, levels of hematocrit, erythrocytes, and leukocytes increased significantly in healthy animals exposed to EO. Exposure to (-)-globulol increased leukocyte number alone. No significant differences in nonspecific immunological parameters were detected when treated groups were compared to controls, but the leukocytosis observed in EO- and globulol-treated healthy animals indicates that EO and (-)-globulol increased innate immunity in these fish. An in vitro antiparasitic effect was observed in both samples.

Treatment of ichthyophthiriasis with photodynamically active chlorophyllin.

Water-soluble chlorophyll (chlorophyllin) exerts pronounced photodynamic activity on fish parasites. In order to determine its potential as a remedy against ectoparasites in fish carps were incubated in water with defined concentrations of chlorophyllin. The main focus of the experiments was on the ciliate Ichthyophthirius multifiliis (Fouquet) which is responsible for considerable losses in livestock in aquaculture. As malachite green, which in the past efficiently cured infected fishes, is banned because of its possible carcinogenicity; no effective remedy is presently available in aquaculture to treat ichthyophthiriasis. Using chlorophyllin, the number of trophonts was significantly reduced (more than 50 %) after 3 h incubation of infested fish at 2 and 4 mg/L and subsequent irradiation with simulated solar radiation. The lack of reinfection after light treatment indicates that also the remaining parasites have lost their multiplication capacity. In the controls (no chlorophyllin and no light, light but no chlorophyllin, or chlorophyllin but no light), no reduction of the I. multifiliis infection was observed. We propose that chlorophyllin (or other photodynamic substances) is a possible effective countermeasure against I. multifiliis and other ectoparasites in aquaculture.

Euduboscquella costata n. sp. (Dinoflagellata, Syndinea), an Intracellular Parasite of the Ciliate Schmidingerella arcuata: Morphology, Molecular Phylogeny, Life Cycle, Prevalence, and Infection Intensity.

The syndinean dinoflagellate Euduboscquella costata n. sp., an intracellular parasite of the tintinnid ciliate Schmidingerella arcuata, was discovered from Korean coastal water in November of 2013. Euduboscquella costata parasitized in about 62% of the host population, with infection intensity (= number of trophonts in a single host cell) ranging from 1 to 8. Based on morphology and nuclear 18S ribosomal RNA gene sequences, the parasite is new to science. Euduboscquella costata n. sp. had an infection cycle typical of the genus, but had morphological and developmental features that distinguished it from congeneric species. These features include: (1) episome of the trophont with 25-40 grooves converging toward the center of the shield; (2) a narrow, funnel-shaped lamina pharyngea extending from the margin of the episomal shield to the nucleus; (3) persistence of grooves during extracellular development (sporogenesis); (4) a single food vacuole during sporogenesis; (5) separation of sporocytes early in sporogenesis, regardless of type of spore formed; and (6) dinospore size (ca. 14μm in length) and shape (bulbous episome with narrower, tapering hyposome). After sporogenesis, E. costata produced four different types of spore that showed completely identical 18S rRNA gene sequences. The gene sequence was completely identical with a previously reported population, Euduboscquella sp. ex S. arcuata, from Assawoman Bay, USA, indicating that the two populations are likely conspecific. Favella ehrenbergii, a widely recorded tintinnid known to host Euduboscquella spp., co-occurred with S. arcuata, but was not infected by E. costata in field samples or during short-term, cross-infection experiments.

Immune protection of Mozambique tilapia (Oreochromis mossambicus) exposed to different infectious doses of ectoparasite (Cryptocaryon irritans)

The objectives of the present study were to standardize a reproducible infection procedure with Cryptocaryon irritans and to examine the effects of infectious dose level on the immune protection in Mozambique tilapia (Oreochromis mossambicus). This study demonstrated that direct enumeration of trophonts on the pectoral fin was useful to quantitatively assess immune protection against C. irritans. The number of trophonts on a pectoral fin was positively correlated with infectious dose of live theronts. Fish immunized by direct exposure under controlled laboratory conditions allowed for in depth examination of the effects of the degree of infectious dose on immune response. There was no significant positive correlation between the initial infectious dose and degree of immune responses. Mozambique tilapia initiated a strong immune protection by direct exposure with even a small number of parasites (e.g. 300 theronts per fish). Moreover, as the result of the protein analysis, we identified 28kD proteins that could be responsible for the immobilizing antigen.

Toltrazuril (Baycox&lt;SUP&gt;®&lt;/SUP&gt; vet.) in feed can reduce &lt;I&gt;Ichthyophthirius multifiliis&lt;/I&gt; invasion of rainbow trout (Salmonidae)

Various compounds have been applied for control of Ichthyophthirius multifiliis (commonly known as Ich) which is the parasitic pathogen, responsible for the white spot disease, in freshwater aquaculture worldwide. Available methods are based on disinfection of fish tank water, targeting infective free-swimming theronts and escaped tomonts. No legal drug is available and licensed for treatment or prevention of the disease. The presently reported study was performed to test the potential of toltrazuril (Baycox® vet.)—a drug licensed for treatment of coccidial infections in other animal species—to reduce Ich infections when administered orally. Commercial pelleted feed containing 5.0 or 2.5 mg toltrazuril per 1 g of feed was offered to rainbow trout, Oncorhynchus mykiss (Walbaum, 1792) (Actinopterygii: Salmoniformes: Salmonidae), during a three day feeding regime (1% of biomass offered per day). Two trials were performed: one with feeding before exposure to parasites and one where already infected fish were treated. Before the treatment it was tested if fish would eat feed containing different drug concentrations and it was found that feed with the high drug concentration was not eaten by the fish whereas all feed containing 2.5 mg per 1 g feed was eaten. Following the exposure to infective I. multifiliis theronts it was found that the fish treated with toltrazuril before challenge obtained a significantly lower parasite burden (number of trophonts in the skin) compared to untreated control. On the other hand, toltrazuril proved to be ineffective when administered to the fish which were already infected before the treatment.

Effects of Short- and Long-Term Glucan Feeding of Rainbow Trout (Salmonidae) on the Susceptibility to &lt;I&gt;Ichthyophthirius Multifiliis&lt;/I&gt; Infections

Background. Various compounds are being used as immuno-stimulants in various aquaculture feed types but the importance of their prolonged use is at present unknown. It is also true for those intended to modify trout susceptibility to white spot disease caused by Ichthyophthirius multifiliis. The immuno-modulating effects on rainbow trout of short- and long-term feeding using dry feed with inclusion of beta-glucan (0.2%) have therefore been evaluated. Materials and methods. The immune reactivity was assessed by measuring susceptibility to I.multifiliisinfections and plasma lysozyme in the host, factors which are considered innate response parameters. Rainbow trout, Oncorhynchus mykiss(Walbaum, 1792) (Actinopterygii: Salmoniformes: Salmonidae),were fed (control feed or glucan-containing feed) for 14 or 35 days before challenge (exposure to infective I. multifiliis theronts) and the resulting infection (number of trophonts in the skin) was recorded on day 11 post-exposure to theronts. Results. All fish obtained infection following parasite exposure but glucan-fed fish showed a lower infection at day 46 compared to fish fed control-feed. The lysozyme activity of fish plasma was evaluated throughout the experimental period and found slightly but significantly increased in association with glucan-feeding at day 14, 17, and 46. Conclusion. No evidence for an exhaustion of these selected innate response parameters due to prolonged glucan-feeding could be detected within the experimental period of 46 days.

Prevention of Ichthyophthirius multifiliis infestation in goldfish ( Carassius auratus) by potassium ferrate(VI) treatment

Ichthyophthirius multifiliis is an important freshwater teleost pathogen that often leads to significant economic losses to the aquaculture industry. The purpose of this study was to assess the acute toxicity of potassium ferrate(VI) to I. multifiliis theront and the concentration needed to prevent I. multifiliis infestation in goldfish, Carassius auratus. Five hundred theronts were exposed to concentrations of potassium ferrate(VI) in each well of a 96-well microtiter plate and observed for 4 h to determine the acute toxicity. Results showed that the exposure of I. multifiliis theronts to potassium ferrate(VI) at concentrations of 4.80 mg/L or more resulted in 100% mortality by 4 h; the LC 50 value was estimated to be 1.71 mg/L. Aqueous static renewal 96-h bioassays were carried out to determine the acute toxicity of potassium ferrate(VI) to goldfish. The LC 50 value for potassium ferrate(VI) in goldfish was 42.51 mg/L. Goldfish were exposed to 4000 theronts/fish in aerated tap water (a dose previously shown to result in consistent infestation) and treated with a single dose of potassium ferrate(VI) after 30 min contact with theronts. Infection level and prevalence were recorded everyday after exposure. The results revealed that potassium ferrate(VI) at the 4.80 mg/L or more concentrations can significantly reduce not only the number of trophonts on the fin of goldfish on day 3 ( P < 0.05), but also the prevalence of ichthyophthiriasis ( P < 0.05). Potassium ferrate(VI) at a concentration of 4.80 mg/L was considered to be the lowest effective dose to prevent infestation of I. multifiliis in goldfish.

Metodologia de infecção experimental e grau de susceptibilidade do híbrido "tambacu" e Leporinus macrocephalus Garavello &amp; Britski (Osteichthyes, Anostomidae) a quatro inóculos de trofozoítos de Icthyophthirius multifiliis Fouquet (Protozoa, Ciliophora)

Tropical fishes like Leporinus macrocephalus Garavello & Britski, 1988 (piaucu) and the hybrid tambacu (Piaractus mesopotamicus Holmberg, 1887 pacu male x Colossoma macropomum Cuvier, 1818 tambaqui female) were experimentally infected with four inocula of trophonts of Ichthyophthirius multifiliis Fouquet, 1876 (Protozoa, Ciliophora) and the infection level was evaluated. Each one of twelve experimental units consisted of a tank with 200 liters of water and two specimens of each kind of fish. The following treatments were designed to each tank, in triplicate: 8, 16,32 and 64 trophonts. After 8 days of exposure the fishes were killed and the number of trophonts was counted at a stereoscopic microscope. This assay showed to be feasible at tropical conditions and was able to show that tambacu was more susceptiblc than piaucu.