TOXICITY OF TAGETES MINUTA ESSENTIAL OIL IN SILVER CATFISH (RHAMDIA QUELEN)

Objective: Evaluation of Tagetes minuta L. essential oil (EOTM) toxicity in the silver catfish Rhamdia quelen.Methods: The EOTM extracted by hydrodistillation was identified qualitatively based on retention indices and the mass spectrum of its components by gas chromatography-mass spectrometry (GC-MS) and quantified by GC with flame ionization detector. Fish were exposed to 0, 50, 100, 200 mg l-1 EOTM and ethanol (1.5 ml) (n = 10 each concentration) and mortality observed after 24, 48 and 96 h (h).Results: The EOTM presented as the main constituents: di-hidrotagetone (7.66 %), Z-tagetone (29.50%) and E-tagetone (40.37%). Silver catfish mortality was 10% after 96 h at 50 mg l-1, 70 and 80% after 24 and 96 h, respectively, at 100 mg l-1 and 80, 90 and 100% after 24, 48 and 96 h, respectively, at 200 mg l-1.Conclusion: The use of EOTM is not recommended in fish farming at the concentrations measured in this study due to its toxic action.Keywords: Medicinal plants, Fish farming, Toxic effect, Cloves marigoldÂ

HEMATOLOGIA DE JUNDIÁS EM RESPOSTA AO NÍVEL DE PROTEÍNA NA DIETA

Neste trabalho avaliou-se a hematologia de machos e fêmeas de jundiá, alimentados com três níveis protéicos: 24, 27 e 30% PB. Um total de 270 peixes (135 machos e 135 fêmeas – peso inicial médio de 216,38 ± 26,73 g) foram alimentados durante 100 dias em um sistema de recirculação de água contendo 18 tanques (seis tratamentos com três repetições). Após esse período, capturaram-se seis peixes por tratamento para coleta de sangue a fim de se obterem os valores de hematócrito, hemoglobina, eritrócitos, volume corpuscular médio, hemoglobina corpuscular média, concentração de hemoglobina corpuscular média e plaquetas. Os machos apresentaram maiores valores (P0,05). Conclui-se que machos de jundiá apresentam parâmetros hematológicos superiores às fêmeas. A proteína dietária influencia na quantidade de plaquetas e na concentração de hemoglobina corpuscular dos jundiás. PALAVRAS-CHAVE: fêmeas; hematócrito; hemoglobina; machos; Rhamdia quelen

Biofilm formation by Rhodococcus equi and putative association with macrolide resistance

Abstract: Rhodococcus equi is a facultative intracellular pathogen, which cause severe pyogranulomatous pneumonia in foals and tuberculosis-like lesions in humans. Its ability to form biofilm was described in strains isolated from chronic diseases associated to treatment failures in humans. This study aimed to verify the biofilm formation by 113 R. equi isolated from equine samples (clinical and fecal) using two different methods (biofilm-culturing with and without additional glucose and epifluorescence microscopy). We also aimed to determine the efficacy of azithromycin, clarithromycin and erythromycin on R. equi in established biofilm. We found 80.5% (26/41) and 63% (58/72) biofilm-positive isolates, in fecal and clinical samples, respectively. The additional glucose increased the biofilm formation by R. equi fecal samples, but not by clinical samples. The antimicrobials tested herein were not able to eradicate R. equi in biofilm even at higher concentrations. This is the first study showing the biofilm formation by R. equi isolated from equine samples. Our findings indicate that R. equi biofilm-producers may be more resistant to the antimicrobials evaluated. Further studies are warranted to test this hypothesis

Clinostomum complanatum (Trematoda, Digenea): a parasite of birds and fishes with zoonotic potential in southern Brazil. A Review

Clinostomum complanatum is a digenean trematoda belonging to the Clinostomidae family with a complex life cycle, usually taking molluscs and fishes as intermediate hosts and birds as final hosts. Man may become the final host by eating raw or undercooked fish meat carrying the metacercarial stage of the parasite. Therefore, this trematode deserves great attention not only for the losses in production and discards of fish carcasses, but also for its zoonotic potential. Parasitic diseases transmitted to man through fish consumption have been especially reported in Eastern countries, where the habit of eating dishes based on raw fish meat is common. Nonetheless, C. complanatum has been reported in free-living fishes and specimens in fish farms in southern Brazil, thus representing a risk to the health of fish consumers. Strict regulations should be implemented in Brazil in order to control the quality of the fish destined for human consumption, and public awareness of the dangers of eating raw fish should be raised.Clinostomum complanatum é um trematoda digenético pertencente à família Clinostomidae com um ciclo de vida complexo, tendo normalmente moluscos e peixes como hospedeiros intermediários e aves como hospedeiros finais. O homem pode tornar-se o hospedeiro final através do consumo de carne de peixe crua ou mal cozida portando as metacercárias. Assim, este parasita merece atenção não só pelas perdas na produção e no descarte de carcaças de peixes que acarreta, mas também pelo seu potencial zoonótico. Parasitoses transmitidas através do consumo de peixes têm sido relatadas especialmente em países do oriente, onde o hábito de consumir pratos que utilizam carne de peixe crua é comum. Entretanto, a presença de C. complanatum em peixes de vida livre e de criações já foi reportada no sul do Brasil, o que representa um risco à saúde dos consumidores de carne de peixe. Regulamentações efetivas devem ser implementadas no Brasil a fim controlar a qualidade do peixe destinado ao consumo humano e os riscos da ingestão de carne de peixe crua devem ser amplamente esclarecidos perante a comunidade

Biofilm formation by Prototheca zopfii isolated from clinical and subclinical bovine mastitis in distinct growth conditions under different dyes

ABSTRACT: Prototheca spp. have been reported as an emergent environmental mastitis pathogen in several countries. Biofilm formation is a significant factor associated with different degrees of virulence developed by many microorganisms, including Prototheca spp. The present study aimed to compare two growth conditions and two staining dyes to determine which combination was more appropriate to evaluate qualitatively and quantitatively the production of biofilm by P. zopfii. Biofilm formation was evaluated in polystyrene microplates under static and dynamic growth conditions and staining with crystal violet or cotton blue dye. All P. zopfii isolates from cows with mastitis were classified as biofilm-producers in all growth conditions and staining. The cotton blue dye proved to be more appropriate method to classify the intensity of P. zopfii biofilm production

The Effects of Stocking Density and Food Deprivation on Mucous Cells and Lysozyme Activity in the Skin and Gills of Silver Catfish

This study aimed to identify the regions of the body surface of silver catfish (Rhamdia quelen) with a higher population of mucous cells in the skin. Additionally, the effects of stressful conditions, such as different stocking densities and food deprivation, on the proliferative response of mucous cells in the skin and gill epithelium and their impact on cutaneous mucous lysozyme activity were investigated. Silver catfish were divided into four experimental groups: high stocking density (32 kg/m3) and fed (HSD-F), high stocking density and fasted (HSD-FS), low stocking density (2.5 kg/m3) and fed (LSD-F), and low stocking density and fasted (LSD-FS). Fish in the fed groups received commercial feed twice a day, amounting to 1% of the tank biomass. After a 14-day experimental period, the fish were anesthetized and euthanized. Samples of cutaneous mucous and skin fragments from seven different points and the second left branchial arch were collected. Histological slides of the skin and gills were stained with PAS + Alcian Blue at pH 2.5, and the epidermal mucous lysozyme activity was assessed using the turbidimetric method. The ventral point in front of the ventral fin was found to be the optimal location for collecting cutaneous epithelia due to its higher density of mucous cells. The population of mucous cells in both the skin and gills varied based on the collection point and treatment applied. The highest lysozyme activity in the epidermal mucous was observed in fish from the HSD-F group. Overall, these findings suggest that stocking density and food deprivation create stressful conditions for silver catfish, which modulate their mucosal response to each situation

Biofilm formation by Rhodococcus equi and putative association with macrolide resistance

Abstract: Rhodococcus equi is a facultative intracellular pathogen, which cause severe pyogranulomatous pneumonia in foals and tuberculosis-like lesions in humans. Its ability to form biofilm was described in strains isolated from chronic diseases associated to treatment failures in humans. This study aimed to verify the biofilm formation by 113 R. equi isolated from equine samples (clinical and fecal) using two different methods (biofilm-culturing with and without additional glucose and epifluorescence microscopy). We also aimed to determine the efficacy of azithromycin, clarithromycin and erythromycin on R. equi in established biofilm. We found 80.5% (26/41) and 63% (58/72) biofilm-positive isolates, in fecal and clinical samples, respectively. The additional glucose increased the biofilm formation by R. equi fecal samples, but not by clinical samples. The antimicrobials tested herein were not able to eradicate R. equi in biofilm even at higher concentrations. This is the first study showing the biofilm formation by R. equi isolated from equine samples. Our findings indicate that R. equi biofilm-producers may be more resistant to the antimicrobials evaluated. Further studies are warranted to test this hypothesis