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Purpose: This study investigated the anthelmintic efficacy of therapeutic baths with the essential oil of Piper marginatum Jacq against the monogeneans Anacanthorus spathulatus Kritsky, Thatcher & Kayton, 1979, Notozothecium janauachensis Belmont-Jégu, Domingues & Laterça 2004, Mymarothecium boegeri Cohen & Kohn, 2005 and Linguadactyloides brinkmanni Thatcher & Krytsky, 1983 in Colossoma macropomum Cuvier, 1818, and its hematological and histopathological effects on this fish., Methods: Short six therapeutic baths with 100 mg/L of the essential oil of P. marginatum and two control groups (water from the cultivation tank and water from the cultivation tank + 70% alcohol) were used for 20 min every two days., Results: The therapeutic baths with 100 mg/L of the essential oil of P. marginatum had efficacy of 42.8% against monogeneans of C. macropomum gills. Toxicity was low for C. macropomum, because there were few physiological and histopathological changes that did not compromise the functioning of the gills of this fish., Conclusion: Short therapeutic baths with 100 mg/L of the essential oil of P. marginatum had low efficacy for controlling monogeneans in C. macropomum and thus cannot be recommended., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The paper describes the effect of Cr–Zn substitution in Sr1−xCrxFe12−yZnyO19 (0 ≤ x ≤ 0.8; 0 ≤ y ≤ 1) hexaferrite, synthesized by the sol–gel auto-combustion method. The prepared samples are examined with XRD and FTIR to ensure the successful formation of the magnetoplumbite hexagonal structure. The magnetic study suggests that the magnetic tunability characteristic of strontium hexaferrite may be utilized to expand the application area from hard to soft magnet applications. The substitution of the Cr3+ ion at Sr site improves the coercivity of the material; however, substituting the Zn2+ ion at Fe site increases the saturation magnetization. A very high value of saturation magnetization, ~ 78 emu/g, is obtained for SrFe11ZnO19 composition with a small coercivity of ~ 64 Oe. A dielectric resonator antenna model is simulated in Ku-band for the proposed application. The obtained results positively suggest the exploration of strontium hexaferrite-based magnets in antenna applications at higher frequencies. [ABSTRACT FROM AUTHOR]

Intensive fish farming with inadequate management can imbalance the fish-pathogen-environment relationship, culminating in diseases outbreaks. In the case of tambaqui Colossoma macropomum farming, it may be affected by acanthocephalosis, a parasitic infection without a specific and safe treatment yet. The objective of this study was to evaluate the effect of the active ingredients in trichlorfon, albendazole, piperazine, and ivermectin, as well as the non-traditional chemists calcium hydroxide and diatomaceous earth incorporated to the feed, to control Neoechinorhynchus buttnerae (Acanthocephala) in tambaqui. A 63-day trial was conducted in a completely randomized experimental design, with 7 treatments, 3 replicates each, and 54 fish per treatment. Fish were sampled for weight gain and parasite count on days 0, 15, 35, and 63. In general, the efficacy of anthelmintics was low in the treatment of N. buttnerae in tambaqui. Nevertheless, among the tested products, calcium hydroxide and diatomaceous earth showed promising results (48.2% and 36.4% efficacy, respectively), followed by ivermectin and piperazine (15.9% and 12.6%, respectively). Future studies are warranted to test longer drug administration periods, novel products, and diverse experimental conditions to treat N. buttnerae in tambaqui, to provide information to develop strategies for disease management. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the use of sodium chloride (NaCl) against monogenoid trematodes infestations in pirarucu (Arapaima gigas). Two assays were conducted with pirarucu juveniles, the first comprising an in vitro exposure to 8, 9, 10, and 11 g·L−1 NaCl and the second, in vivo exposure test to NaCl at the same concentrations. The best in vitro results were observed for 1-h exposures at 9, 10, and 11 g·L−1 NaCl, resulting in 60% and 100% parasite mortality, respectively. In vivo exposures to 8 and 10 g·L−1 NaCl were 36 and 22% efficient, respectively, following 2 h of exposure, with no mortality. Some dose-dependent changes were observed in exposed fish, such as decreased hemoglobin and MCHC values at the highest NaCl concentration compared to the other NaCl concentrations and the control group. Most frequent gill tissue alterations observed were capillary dilatation and mucus secretions compared to the control group at the highest NaCl concentrations (10 and 11 g·L−1). Decreased mean (p < 0.05) water pH values and increased mean electrical conductivity were noted compared to the control group. In conclusion, our findings suggest that NaCl exhibits low toxicity toward pirarucu without physiological alterations and anthelmintic activity to the monogenoid directly influenced by exposure time and concentration. Moreover, 100% of the monogenoids present in the gills of the fish were identified as Dawestrema cycloancistrium. [ABSTRACT FROM AUTHOR]

Background: With the expansion of animal production, parasitic helminths are gaining increasing economic importance. However, application of several established deworming agents can harm treated hosts and environment due to their low specificity. Furthermore, the number of parasite strains showing resistance is growing, while hardly any new anthelminthics are being developed. Here, we present a bioinformatics workflow designed to reduce the time and cost in the development of new strategies against parasites. The workflow includes quantitative transcriptomics and proteomics, 3D structure modeling, binding site prediction, and virtual ligand screening. Its use is demonstrated for Acanthocephala (thorny-headed worms) which are an emerging pest in fish aquaculture. We included three acanthocephalans (Pomphorhynchus laevis, Neoechinorhynchus agilis, Neoechinorhynchus buttnerae) from four fish species (common barbel, European eel, thinlip mullet, tambaqui). Results: The workflow led to eleven highly specific candidate targets in acanthocephalans. The candidate targets showed constant and elevated transcript abundances across definitive and accidental hosts, suggestive of constitutive expression and functional importance. Hence, the impairment of the corresponding proteins should enable specific and effective killing of acanthocephalans. Candidate targets were also highly abundant in the acanthocephalan body wall, through which these gutless parasites take up nutrients. Thus, the candidate targets are likely to be accessible to compounds that are orally administered to fish. Virtual ligand screening led to ten compounds, of which five appeared to be especially promising according to ADMET, GHS, and RO5 criteria: tadalafil, pranazepide, piketoprofen, heliomycin, and the nematicide derquantel. Conclusions: The combination of genomics, transcriptomics, and proteomics led to a broadly applicable procedure for the cost- and time-saving identification of candidate target proteins in parasites. The ligands predicted to bind can now be further evaluated for their suitability in the control of acanthocephalans. The workflow has been deposited at the Galaxy workflow server under the URL tinyurl.com/yx72rda7. [ABSTRACT FROM AUTHOR]

This study explored the effects of the essential oil of Ocimum basilicum (EOOB) and ginger extract (GE) during the transportation of pearl gentian grouper from water quality, serum biochemistry, oxidative stress, meat flavor, and gill tissue morphology. Fish (450 ± 50 g) were allocated to the following 5 treatments: control group (fish transported in water only), 5 mg/LEOOB, 10 mg/LEOOB, 3 mg/LGE, and 6 mg/LGE and transported in insulation boxes (66 × 51 × 37.8 cm) for 72 h. Samples were taken at 0, 12, 36, 60, and 72 h immediately after transport. It was found that 10 mg/LEOOB and 6 mg/LGE could reduce the levels of total ammonia nitrogen (TAN), dissolved oxygen (DO), water pH, serum glucose (GLU), cortisol (COR), liver superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and glutathione peroxidase (GPX), increase the activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), as well as significantly increase the total free amino acid (TFAA) content in muscle compared to the control group (P < 0.05). In addition, by observing the microstructure of gill tissue, it was found that compared with untreated grouper, the morphological damage of gill tissue in EOOB and GE treatment was alleviated. These results indicated that adding appropriate amounts of EOOB and GE to transport water could improve the water quality, relieve stress, and lower energy metabolism of grouper during transport. The results of this research will help to improve the survival rate of grouper after transportation and decrease economic losses to fishery., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Occurrences of parasitic infections caused by Neoechinorhynchus buttnerae in Colossoma macropomum (tambaqui), especially in the northern region of Brazil, have increased in the past two decades and have caused economic losses in tambaqui production. The aim of this study was to evaluate the in vivo efficacy and clinical safety of fenbendazole and levamisole in controlling and treating N. buttnerae in tambaqui for 30 days. Juvenile tambaqui naturally infected with N. buttnerae were distributed in 15 tanks (n = 12 per 1,000 L-tank), constituting five treatments, in triplicate. Treatments were administered via diet (mg kg−1 of live weight): control (0 mg kg−1), F1 (100 mg kg−1 of fenbendazole), F2 (200 mg kg−1 of fenbendazole), L1 (200 mg kg−1 of levamisole), and L2 (300 mg kg−1 of levamisole). Fish survival rate was 100% during the entire experimental period. Fenbendazole treatments were not effective against N. buttnerae; however, L1 and L2 showed efficacy of 73.4 and 99.15%, respectively. Treatments with fenbendazole or levamisole did not affect the growth parameters of tambaqui. F1 and F2 showed significant reduction in the hematocrit values when compared to L1, and hemoglobin values were significantly reduced in F1 when compared to L1, L2, and the control group. There were no significant differences in RBC, MCV, and CHCM. The plasma glucose value was statistically lower in F1 than in the L1 (p = 0.03) and L2 (p = 0.02) treatments. For alanine aminotransferase, there was a significant reduction (p = 0.004) in the F1 and F2 groups compared to the L2 group. No statistical difference was observed for aspartate aminotransferase among the treatments. More studies are warranted to further evaluate other therapeutic strategies using shorter periods for controlling and efficiently treating N. buttnerae. [ABSTRACT FROM AUTHOR]

Background: A central question in parasitology is why parasites mature and reproduce in some host species but not in others. Yet, a better understanding of the inability of parasites to complete their life cycles in less suitable hosts may hold clues for their control. To shed light on the molecular basis of parasite (non-)maturation, we analyzed transcriptomes of thorny-headed worms (Acanthocephala: Pomphorhynchus laevis), and compared developmentally arrested worms excised from European eel (Anguilla anguilla) to developmentally unrestricted worms from barbel (Barbus barbus). Results: Based on 20 RNA-Seq datasets, we demonstrate that transcriptomic profiles are more similar between P. laevis males and females from eel than between their counterparts from barbel. Impairment of sexual phenotype development was reflected in gene ontology enrichment analyses of genes having differential transcript abundances. Genes having reproduction- and energy-related annotations were found to be affected by parasitizing either eel or barbel. According to this, the molecular machinery of male and female acanthocephalans from the eel is less tailored to reproduction and more to coping with the less suitable environment provided by this host. The pattern was reversed in their counterparts from the definitive host, barbel. Conclusions: Comparative analysis of transcriptomes of developmentally arrested and reproducing parasites elucidates the challenges parasites encounter in hosts which are unsuitable for maturation and reproduction. By studying a gonochoric species, we were also able to highlight sex-specific traits. In fact, transcriptomic evidence for energy shortage in female acanthocephalans associates with their larger body size. Thus, energy metabolism and glycolysis should be promising targets for the treatment of acanthocephaliasis. Although inherently enabling a higher resolution in heterosexuals, the comparison of parasites from definitive hosts and less suitable hosts, in which the parasites merely survive, should be applicable to hermaphroditic helminths. This may open new perspectives in the control of other helminth pathogens of humans and livestock. [ABSTRACT FROM AUTHOR]

Within the rich diversity of South American freshwater fish, Colossoma macropomum (Characiformes: Serrasalmidae), known as tambaqui, cachama or blackfin pacu, can reach 30 kg, is a traditional product in regional fish markets and has drawn the attention of fish farmers since the 1930s. Considerable progress achieved in different fields of aquaculture science has contributed to the growth of tambaqui production. Tambaqui has proven suitable for both monoculture and polyculture systems, and for both extensive and intensive production systems aimed at achieving sustainable, higher productivity with minimal environmental impact. Studies of the reproductive anatomy and physiology of the species proved fundamental to development of techniques to boost commercial production, contributing to development of protocols for hormonally induced spawning and artificial propagation in the 1970s. Newly hatched larvae must be fed with live foods until they can be weaned to artificial feeds at about 100 mg weight. Despite its importance for aquaculture, only a few studies have reported components of quantitative genetic variance and parameters for weight at age, morphometric traits and disease resistance. Genomic tools currently available can be applied to detect variation relevant to performance and to accelerate the process of genetic improvement. While the species' feeding habit allows the use of diets containing 75%–85% plant protein, much more work needs to be done to optimize aquafeeds. Refinement of tambaqui production methods has the potential to significantly boost South American aquaculture. We recommend research on diets, genetic improvement and system optimization to spur further productivity and achieve sustainable tambaqui culture. [ABSTRACT FROM AUTHOR]

This study aimed to determine the dietary lysine requirements of juvenile Colossoma macropomum tambaqui based growth performance, hepatic and intestinal morphohistology and hematology. Tambaqui were fed with levels of 6.60, 9.72, 12.84, 15.96, 19.08, and 22.20 g/kg of total lysine and those who received 15.96 g/kg dietary lysine showed higher final weight (p= 0.001) and optimized feed conversion ratio (p= 0.001). Morphohistological modifications (presence of fat droplets) were present in livers of fish fed with low levels of lysine. In the morphohistology of the intestine, the diets influenced the density of the intestinal, cell layers, height and perimeters of the villi and acid mucin secretion by the goblet cells. In the proximal intestine, mucosa layer density was greater at the level of 15.96 g/kg (p= 0.001). In the middle intestine, height (p= 0.001) and perimeter (p= 0.001) of the villi were greater at low levels of lysine (respectively, 9.72 and 12.84 g/kg dietary lysine). No differences were found for the hemoglobin, hematocrit, erythrocytes, MCV, MCH, MCHC, thrombocytes and leukocytes differentiated of fish fed with experimental diets (p>0.05). The biochemical responses were affected by the diet, both in plasma concentration (protein and cholesterol; p<0.05), and in muscle (ash and moisture; p<0.05). In conclusion, the dietary requirement for lysine for tambaqui juveniles was estimated to be 15.4 - 15.6 g/kg of diet (5.7% –5.8% dietary protein). [ABSTRACT FROM AUTHOR]

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This study investigated the efficacy of trichlorfon against Neoechinorhynchus buttnerae, as well as its palatability, residue analysis, and the blood parameters of Colossoma macropomum. At the beginning of the experiment, all previously examined fish were infected with N. buttnerae. There were no differences in mean intensity and mean abundance of N. buttnerae within each treated group and the control group; however, efficacy of 53.4% was found in fish fed with diets containing 1.0 g kg−1 of trichlorfon. Treated fish presented an increase in plasma glucose, while fish fed with diets containing 0.75 and 1.0 g kg−1 of trichlorfon presented an increase in plasma alanine aminotransferase levels. In the higher of the two concentrations, an increase in plasma aspartate aminotransferase levels also occurred. After 96 h, trichlorfon residues were found in the muscle of fish fed with diets containing 0.75 and 1.0 g kg−1 of trichlorfon. No mortality of fish was observed; however, since adverse reactions occurred, and due to palatability problems associated with treatments, 1.0 g kg−1 of trichlorfon could be used for 15 days to control infections by N. buttnerae, though, due to the risk of toxicity, this treatment is not recommended for regular use. As such, precautions should be taken even when using low concentrations of trichlorfon for treatments against this acanthocephalan, as well as in relation to the period of elimination of the trichlorfon residues from fish muscle in order to guarantee safe consumption. [ABSTRACT FROM AUTHOR]