Evidence of Centrocestus formosanus (Nishigori, 1924) in Zebrafish (Danio rerio)

Good practices in the rearing and maintenance of zebrafish (Danio rerio) in Brazilian laboratories

Abstract Good Laboratory Practice (GLP) is a management quality control system that encompasses the organizational process and conditions under which non-clinical health and environmental studies are carried out. According to the World Health Organization, GLP must contain five topics: resources, characterization, rules, results, and quality control. This work aims to address a review according to WHO standards of implementing Good Laboratory Practices in zebrafish (Danio rerio) vivariums. Considering that the promotion of one health (animal, human, and environmental) associated with an education plan, protocols, and records are fundamental to guarantee the safety and integrity of employees, animals, and the environment as well as reliability in the results generated. In a way, Brazil still needs improvements related to the well-being of aquatic organisms (national laws, international agreements, corporate programs, and others), especially concerning its use in research and technological development. In this way, the implementation of GLPs provides valuable guidance for improving animal welfare and worker safety, facilitating the standardization of research.

Boas práticas na criação e manutenção de zebrafish (Danio rerio) em laboratório no Brasil

Resumo As Boas Práticas de Laboratório (BPL) são um sistema de controle de qualidade gerencial que abrange o processo organizacional e as condições sob as quais os estudos não clínicos de saúde e meio ambiente são desenvolvidos. Conforme a Organização Mundial da Saúde (OMS) as BPL devem conter cinco tópicos: recursos, caracterização, regras, resultados e controle de qualidade. O objetivo deste trabalho foi apresentar uma revisão conforme o padrão da OMS para a implementação das BPL em biotério de zebrafish. Considerando que a promoção da saúde única (animal, humana e ambiental) associada a um plano de educação, protocolos e registros são fundamentais para garantir a segurança e a integridade dos trabalhadores/pesquisadores, animais e meio ambiente assim como confiabilidade nos resultados gerados. De certa forma o Brasil ainda necessita de melhorias relacionadas ao bem-estar de organismos aquáticos (leis nacionais, acordos internacionais, programas corporativos e outros); especialmente em relação à utilização deste na pesquisa e desenvolvimento tecnológico. Desta forma, a implementação de BPL fornece uma orientação valiosa para a melhoria do bem-estar animal, e segurança do trabalhador vindo a facilitar a padronização da pesquisa.

FELASA-AALAS Recommendations for Biosecurity in an Aquatic Facility, Including Prevention of Zoonosis, Introduction of New Fish Colonies, and Quarantine

FELASA and AALAS established a joint working group to advise on good practices for the exchange of fish for research. In a first manuscript, the working group made recommendations for health monitoring and reporting of monitoring results. The focus of this second related manuscript is biosecurity in fish facilities. First, we define the risk of contamination of personnel by zoonotic pathogens from fish or from system water, including human mycobacteriosis. Preventive measures are recommended, such as wearing task-specific personal protective equipment. Then we discuss biosecurity, highlighting the establishment of biosecurity barriers to preserve the health status of a facility. A functional biosecurity program relies on integration of the entire animal facility organization, including the flow of staff and animals, water treatments, and equipment sanitation. Finally, we propose 4 steps for introducing new fish colonies: consideration of international trade and national restrictions; assessing risk according to fish source and developmental stage; establishing quarantine barriers; and the triage, screening, and treatment of newly imported fish. We then provide 3 realistic sample scenarios to illustrate practical biosecurity risk assessments and mitigation measures based on considerations of health status and quarantine conditions.

Toxicological assessment of CeO2 nanoparticles on early development of zebrafish

Nanomaterials involve an active research and a booming area including different fields (health, environment, electronics, manufacturing, drug delivery). Recently, new concerns are emerging about the risk from increased production and subsequent release into the environment, as they are largely present in consumer products and industrial applications. Our aim was to assess the effects of three different types of cerium oxide nanoparticles (CeO2 NPs) (type 1 defined "as prepared"; type 2 defined "modified"; type 3 defined "commercial") on zebrafish embryos by Fish Embryo Toxicity test (Z-FET). Immunohistochemical analysis was also performed on treated larvae to evaluate the expression of the following biomarkers: Metallothionein, Heat Shock Protein 70 (HSP70) and 7-Ethoxyresorufin-O-Dietylase (EROD). After 96 h of exposure, there was no lethality, nor were there sub-lethal effects in embryonic development, when compared with the control. No particular positivity was found about Metallothionein and HSP70 expression, while an increased expression of EROD was observed in larvae exposed to the three types of CeO2 NPs compared with the controls. The analyze has confirmed a statistically significant difference (P < 0.001) to EROD biomarker between control group and treated larvae response, finding was higher at 1-mg/l concentration. Further investigations in order to solve conflicting views about potential effects of CeO2 NPs are necessary, also to evaluate its effectiveness in different fields as already reported in literature.

First Record of Clinostomum sp. (Digenea: Clinostomidae) in Danio rerio (Actinopterygii: Cyprinidae) and the Implication of Using Zebrafish from Pet Stores on Research

Many scientific studies still use zebrafish from pet stores as animal models, even cutting-edge researches. However, these animals differ genotypically and phenotypically between them. The importance of the use of standardized models is widely recognized. Besides that, another consequence of using zebrafish from unknown origins is the acquisition of parasitized animals. This study aimed to relate the infection by Clinostomum sp. in zebrafish. Animals sold as "high standard" were acquired from a commercial company. Swimming alterations and superficial yellow dots were observed in five zebrafish with clinical signs, which were isolated, euthanized, and necropsied. Muscular yellow cysts with metacercaria associated with lesions were observed. The muscular cysts were responsible for the superficial yellow dots as well as the swimming alterations. The prevalence was 2.5%, and the mean infection intensity was 7 digeneans/host. The cysts measured a mean of 1251.43 μm long × 784.28 μm wide. Metacercariae measured a mean of 4847 μm long × 1353 μm wide. This first report about infection by Clinostomum sp. in zebrafish is globally relevant since the host and the parasite genus currently overlap worldwide. Furthermore, this study sheds light on the importance of the specific pathogen-free commercial creations or laboratory-reared zebrafish for research.

Testicular leiomyoma and spermatogenic failure syndrome in a seabass from broodstock

Testicular leiomyomas and gonadal dysfunctions are not commonly reported in teleost and particularly in broodstock fish. In the present work, a testicular leiomyoma related to an unusual case of spermatogenic failure syndrome, in a broodstock seabass coming from an Italian aquaculture farm, is reported. At gross pathology, the circumscribed neoplasia showed several white nodular masses, originating from the gonad, deforming the anatomo-physiological shape. From light microscopy, the presence of neoplastic tissue islands with spindle cells with a whirling pattern and the low presence of connective tissue were evident and originated from smooth muscle cells. Seminiferous tubules showed severe azoospermia with the absence of sperm cells even closer to the neoplastic area. Immunohistochemical analysis was positive for alpha-SMA, desmin and vimentin but negative for S-100, confirming a diagnosis of leiomyoma. This is the first report of spermatogenic failure syndrome associated with a testicular leiomyoma in fish from broodstock. More efforts should be made in studying broodstock fish pathologies related to fish maintenance and hormonal treatments that could economically affect aquaculture production.

Prevalence of Bovine Tuberculosis in Slaughtered Cattle in Sicily, Southern Italy

Simple Summary

Mycobacterium bovis is a Gram-positive, acid-fast bacterium responsible for disease in cattle and in several other domestic and wild animal species, also representing a prominent cause of morbidity and mortality in humans. In Italy, the incidence of bovine tuberculosis (bTB) in cattle has been progressively reduced throughout the years; however, the disease still remains widespread in Southern Italy, with the highest prevalence rates recorded in Sicily. Specific eradication programs have been established, with herd testing and post-mortem inspection at the slaughterhouse used as diagnostic procedures to obtain epidemiological data on bTB prevalence. The concomitant use of these procedures is essential in epidemiological surveillance programs, and although data on disease prevalence at herd level are systematically collected and used for epidemiological surveillance in Sicily, data from post-mortem inspection are scant. Therefore, the current survey aimed to investigate the prevalence of bTB in cattle in Sicily during two different three-year periods, using data from meat inspections and histopathological methods. Results obtained show that even though bTB occurrence in cattle was well reduced over the years, the disease still remains widespread in this region, posing severe implications for public health and a prominent economic impact on the livestock industry.

Abstract

Post-mortem inspection in slaughterhouses plays a key role in the epidemiological surveillance of infectious diseases, including bTB. This study assessed the prevalence of bTB in cattle in Sicily during two different three-year periods (2010–2012; 2017–2019), using data from meat inspections and histopathological methods. Out of 100,196 cattle, 5221 (5.21%) were diagnosed with tuberculous lesions. Higher prevalence of bTB was recorded during the triennium 2010–2012 (6.74%; n = 3692) compared to the triennium 2017–2019 (3.36%; n = 1529), with a decreasing trend in annual occurrence throughout the study period and a heterogenous proportion of infected cattle among the Sicilian provinces (p < 0.01). Lower rates of infection were recorded in animals aged <12 months and >84 months (p < 0.0001). Pearson’s chi square analysis revealed a higher localization of lesions in the thoracic cavity (p < 0.0001). Gathered findings show that even though bTB occurrence in cattle was greatly reduced over the years, the disease still remains widespread in Sicily, also posing severe implications for public health.

The Impact on Antioxidant Enzyme Activity and Related Gene Expression Following Adult Zebrafish (Danio rerio) Exposure to Dimethyl Phthalate

Simple Summary

Dimethyl phthalate (DMP) is a widespread environmental contaminant and its toxicological effects on fish have not been adequately examined. Our present study clearly showed that a high concentration induced oxidative damage in zebrafish, which proved the molecular regulation due to the negative effects of DMP, along with the physical damage in zebrafish. We also found that antioxidant enzymes might be used as appropriate biochemical markers for the toxic identification of DMP.

Abstract

Dimethyl phthalate (DMP) is a widespread environmental contaminant that poses potential toxicity risks for animals and humans. However, the toxicological effects of DMP on fish have not been adequately examined. In this study, the acute toxicity, oxidative damage, antioxidant enzyme activities, and relative gene expression patterns were investigated in the liver of adult zebrafish (Danio rerio) exposed to DMP. We found that the lethal concentration (LC₅₀) of DMP for zebrafish after 96 h of exposure was 45.8 mg/L. The zebrafish that were exposed to low, medium and high concentrations of DMP (0.5, 4.6, and 22.9 mg/L, respectively) for 96 h had an increased malondialdehyde (MDA) content and a lower antioxidant capacity compared with the control solvent group. The total superoxide dismutase (SOD) activity was significantly higher than 0 h after initial exposure for 24 h at low concentrations, and then decreased at high concentrations after exposure for 96 h. The catalase (CAT) and glutathione S-transferase (GST) activities were significantly reduced after 96 h of exposure to high concentrations of DMP, with the up- or down-regulation of the related transcriptional expression. These findings indicated that DMP could cause physiological effects in zebrafish by disturbing the expression levels of antioxidant enzymes. These results might contribute to the identification of biomarkers to monitor phthalate pollution.

Diagnosis of Centrocestus formosanus Infection in Zebrafish (Danio rerio) in Italy: A Window to a New Globalization-Derived Invasive Microorganism

Simple Summary

Centrocestus formosanus is an invasive parasite which originated from outside the European countries. Infections by this parasite seem to be related to the movements of its hosts. However, in Europe, the presence of C. formosanus has been sporadically reported and its zoonotic potential is still underestimated. Therefore, the present study proposes a fast and inexpensive diagnostic method through molecular analyses targeting the ribosomal internal transcribed sequence 2 (ITS2) using a newly designed species-specific primer pair. Given the potential negative consequences of C. formosanus global expansion, those responsible should adopt a one health approach to control the spread of this organism.

Abstract

Centrocestus formosanus is a digenetic trematode with a complex life cycle, involving invertebrate and vertebrate hosts, humans included. In particular, it causes gill lesions and mortality in freshwater fish species, and gastrointestinal symptoms in infected humans. Here, we describe the occurrence of C. formosanus infection in zebrafish imported in Italy and propose a newly designed species-specific primer pair to ameliorate the diagnostic investigations for C. formosanus. Gill arches of 30 zebrafish were examined for the presence of encysted metacercariae under a stereomicroscope and processed through molecular analyses targeting the ribosomal internal transcribed sequence 2 (ITS2). Although C. formosanus distribution was originally restricted to Asia, it has been subsequently reported in new countries, revealing itself as an invasive species and raising important concerns for biodiversity, economy, scientific research, as well as animal and public health. Given the crucial role played by the ornamental fish industry in spreading this parasite, there is an urgent need for control measures to prevent the introduction and establishment of C. formosanus in non-endemic areas, including Europe. We also suggest developing new strategies in microbiology and epidemiology to better explore this new globalization-derived invasive species.

Gastric leiomyoma in a sea bass Dicentrarchus labrax broodfish

This report describes a spontaneously arising non-infiltrative neoplasm of gastric tunica muscularis in a broodstock sea bass Dicentrarchus labrax from an Italian aquaculture farm. Microscopically, the mass was circumscribed and non-encapsulated and was composed of spindle cells arranged in parallel interlacing bundles or, occasionally, a whirling pattern. Cells had a small quantity of eosinophilic cytoplasm with distinct cell borders. Neoplastic cells were immuno-reactive with smooth muscle actin, vimentin and desmin; S100 was negative. The mucosal epithelium was intact with no neoplastic involvement. A gastric leiomyoma was diagnosed based on the findings. More efforts should be made to study the possible etiology of leiomyoma affecting fish from aquaculture.