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 Prototheca zopfii isolated from clinical and subclinical bovine mastitis in distinct growth conditions under different dyes / Formação de biofilme por Prototheca zopfii isolados de mastite bovina clínica e subclínica em distintas condições de crescimento sob diferentes corantes

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.

RESUMO: Prototheca spp. tem sido relatado como um patógeno ambiental causador de mastite bovina em vários países. A formação de biofilme é um fator associado a diferentes graus de virulência desenvolvidos por muitos microrganismos, incluindo Prototheca zopfii. O presente estudo teve como objetivo comparar duas condições de crescimento e dois corantes para determinar a combinação mais adequada para avaliar qualitativa e quantitativamente a produção de biofilme por P. zopfii. A formação de biofilme foi avaliada em microplacas de poliestireno sob condições estáticas e dinâmicas de crescimento e coloração com cristal violeta ou azul de algodão. Todos os isolados de P. zopfii de vacas com mastite foram caracterizados como produtores de biofilme, independentemente das condições de crescimento e coloração. O corante azul de algodão demonstrou ser o método mais adequado para classificar a intensidade de produção de biofilme de P. zopfii.

Growth of silver catfish ( Rhamdia quelen ) exposed to acidic pH at different humic acid levels / Crescimento de jundiás (Rhamdia quelen) expostos ao pH ácido em diferentes níveis de ácido húmico

ABSTRACT: Humic substances are organic compounds that possess high molecular weight and are formed by the decomposition of plant materials. Humic substances comprise humic acids, fulvic acids and humin. Humic acids (HA) have shown to be able to provide some protection to biological membranes of fish in water with low pH, replacing the protective action of Ca2+. Thus, this studyaimed to observe growth of silver catfish ( Rhamdia quelen ) juveniles exposed to pHs 5.5 and 6.5 and to different levels of HA: 0, 10, 25 and 50mg L-1. Results showed that, irrespective of pH, HA was highly detrimental to silver catfish growth, since the higher the concentration of HA, the lower the weight gain and feed intake, resulting in lower biomass and lower specific growth rate of juveniles. Hence, HA is extremely damaging to the performance of silver catfish juveniles in the tested concentrations.

RESUMO: Substâncias húmicas são compostos orgânicos que possuem elevado peso molecular e são formadas pela decomposição da matéria orgânica de plantas. As substâncias húmicas compreendem ácidos húmicos, ácidos fúlvicos e humina. Os ácidos húmicos (AH) têm mostrado serem capazes de proporcionar proteção parcial das membranas biológicas de peixes em águas com baixo pH, substituindo a ação protetora do Ca2+. Assim, este estudo teve como objetivo observar o crescimento de juvenis de jundiá ( Rhamdia quelen ) expostos a pH's 5,5 e 6,5 com diferentes níveis de AH: 0, 10, 25 e 50mg L-1. Os resultados demostram que, independentemente do pH, o AH foi altamente prejudicial para o crescimento do jundiá, uma vez que, quanto maior era a concentração de AH, menor era o ganho de peso e a ingestão de alimentos, resultando em menor biomassa e taxa de crescimento específico inferior dos juvenis. Assim, os AH são extremamente prejudiciais para o desempenho de juvenis de jundiá nas concentrações testadas.

Imazapyr+imazapic herbicide determines acute toxicity in silver catfish Rhamdia quelen.

Imazapyr (IMY) and imazapic (IMI) are imidazolinone herbicides which have been associated in a commercial formulation (Kifix(®)). To date, there are no studies on the toxicity of an IMY+IMI herbicide in fish. This work aimed to assess the acute toxicity (24 and 96 h) of IMY+IMI (0, 0.488 and 4.88 µg/L) towards Rhamdia quelen through hematological, biochemical, immunological, ionoregulatory and enzymatic indexes. Red blood cell count was lower at 4.88 than at 0.488 µg/L (24 and 96 h); mean corpuscular volume was lower than control at both concentrations (24 h) and at 0.488 µg/L (96 h); lymphocytes declined at 4.88 µg/L comparing to control (96 h); and monocytes increased at 4.88 µg/L (96 h) in comparison with the respective control and with 4.88 µg/L at 24h. Aspartate aminotransferase was higher at 0.488 µg/L (96 h) than the respective control and the respective concentration at 24 h; uric acid reduced at 4.88 µg/L comparing with 0.488 µg/L (96 h); and cortisol was lower at 4.88 µg/L compared to 0.488 µg/L and control (96 h). Herbicide exposure lowered plasma bactericidal activity at both concentrations (24 h) and at 0.488 µg/L (96 h); and plasma complement activity declined at 4.88 µg/L comparing with 0.488 µg/L and control (96 h), and was lower at all concentrations at 96 h than at 24 h. Plasma K(+) levels were higher at 4.88µg/L than in the remaining groups (24 and 96h); and Na(+) levels decreased at 4.88 µg/L compared to control (96 h). Na(+)/K(+)-ATPase and H(+)-ATPase activities in gills were lower at 4.88 µg/L comparing with control (24 h) and with the respective concentration at 96 h; and AChE activity in brain was higher at 0.488 and 4.88 µg/L than control (24 h) and the respective concentrations at 96 h, while in muscle it was higher at 0.488 and 4.88 µg/L than control (96 h) and the respective concentrations at 24 h. The present findings demonstrate that, despite IMY+IMI targets the animal-absent AHAS enzyme, such formulation displayed an acute toxic effect upon R. quelen homeostasis by impacting on vital functions such as immune defense, metabolism, ionoregulation and neurotransmission.

Biofilm formation by Rhodococcus equi and putative association with macrolide resistance / Formação de biofilme por Rhodococcus equi e possível associação com resistência a macrolídeos

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...

Rhodococcus equi é um patógeno intracelular facultativo, o qual causa pneumonia piogranulosa severa em potros e lesões semelhantes à tuberculose em humanos. A sua capacidade de formar biofilme foi descrita em cepas humanas, isoladas a partir de doenças crônicas associadas a falhas de tratamento. Este estudo teve como objetivo verificar a formação de biofilme por 113 cepas de R. equi, isoladas a partir de amostras de equinos (clínicas e fecais), utilizando-se dois diferentes métodos (biofilme em cultura - com e sem adição de glicose - e microscopia de epifluorescência). Além disso, buscou-se determinar a eficácia da azitromicina, claritromicina e eritromicina sobre biofilme consolidado de R. equi. Verificou-se 80,5% (26/41) e 63% dos isolados (58/72) positivos para formação de biofilme, em amostras fecais e clínicas, respectivamente. A adição de glicose amentou a formação de biofilme em amostras fecais, mas não em amostras clínicas. Os antimicrobianos aqui testados não foram capazes de erradicar R. equi em biofilme consolidado, mesmo em concentrações elevadas. Este é o primeiro estudo a demonstrar a formação de biofilme por cepas de R. equi isoladas a partir de amostras de equinos. Os resultados indicam que os isolados de R. equi produtores de biofilme podem ser mais resistentes aos antimicrobianos avaliados. Estudos adicionais são necessários para testar essa hipótese...

Ação dos desinfetantes sobre a adesão e biofilme consolidado de staphylococcus spp / Action of products based on chlorhexidine and iodine for the adhesion and consolidated biofilm of staphylococcus spp isolated from milk

Staphylococcus spp. são reconhecidos como importantes causadores de mastites em rebanhos leiteiros. Esses micro-organismos têm a capacidade de produzir uma estrutura denominada biofilme, que é responsável pela sobrevivência e muitas vezes pela resistência a ação de produtos desinfetantes e as demais condições adversas. Neste trabalho avaliou-se a ação de dois produtos pós-dipping a base de iodo (0,7%) e clorexidine (2,0%) sobre a adesão de Staphylococcus coagulase positiva (SCP) e Staphy-lococcus coagulase negativa (SCN) isolados de casos de mastite subclínica, e também sobre biofilmes pré formados a partir destes isolados. Os produtos testados apresentaram uma alta redução na taxa de adesão de todos os isolados. No entanto, a ação sobre os biofilmes consolidados só foi estatisticamente significativa sobre os SCN. Assim, ressalta-se a importância dos programas sanitários a fim de prevenir a formação de biofilmes e diminuir as fontes de contaminação da glândula mamaria em sistemas de produção leiteira.

Staphylococcus spp. are recognized as important causes of mastitis in dairy herds. These microorganisms have the ability to produce a structure called biofilm, which is responsible for the survival and often for resistance to the action of disinfectants and other harsh conditions. In this paper we evaluate the action of two teat dip products based on iodine (0,7%) and chlorhexidine (2,0%) on the adhesion of coagulase-positive staphylococci (CPS) and coagulase negative staphylococci (CNS) from subclinical mastitis cases, and also on its consolidate biofilm. The products tested showed a high reduction on the adhesion of all isolates. However, action on the consolidate biofilm was significant for CNS only, and unsatisfactory for CPS. Thus, it emphasizes the importance of health programs to prevent biofilm formation and reduce the sources of contamination of the mammary gland in dairy production systems.

Hematological, morphological, biochemical and hydromineral responses in Rhamdia quelen sedated with propofol.

Rhamdia quelen morphophysiological responses to propofol sedation were examined. The purpose was to investigate whether propofol would be a suitable drug to be used in fish transport procedures. Fish were exposed to 0, 0.4 or 0.8 mg L(-1) propofol for 1, 6 or 12 h in 40 L tanks, simulating open transport systems. Propofol was able to prevent the peak of cortisol levels experienced by the group exposed to 0 mg L(-1) propofol at 1 h. At 0.4 mg L(-1), propofol also preserved the stability of hematological (hematocrit, red blood cell count, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration), morphological (red blood cell area), biochemical (cortisol, glucose, lactate, total protein, ammonia, urea, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase) and hydromineral (Na(+), Cl(-) and K(+) plasma levels) indicators of stress. Such results suggest that sedation with propofol at 0.4 mg L(-1) is suitable for R. quelen transport.

The use of eugenol against Aeromonas hydrophila and its effect on hematological and immunological parameters in silver catfish (Rhamdia quelen).

The aim of this study was to evaluate the activity of eugenol against the fish pathogen Aeromonas hydrophila and eugenol's effect on hematological and natural immune parameters in silver catfish (Rhamdia quelen). In vitro, eugenol showed weak activity against A. hydrophila, but in vivo, at a subinhibitory concentration (10 mg L(-1)), it promoted survival in infected silver catfish. Eugenol (50 µg mL(-1)) reduced the hemolytic activity of A. hydrophila supernatant in vitro in fish erythrocytes. Subjecting catfish to eugenol baths (5 and 10 mg L(-1)) for five days did not alter the hematological and immunological parameters studied in this work. Based on these results, eugenol can be used to treat or prevent bacterial diseases in fish.

Alimentação de fêmeas de jundiá com fontes lipídicas e sua relação com o desenvolvimento embrionário e larval / Use of lipid sources on feeding jundiá (Rhamdia quelen) and its relation with embryo and larval development

O objetivo deste trabalho foi avaliar a eficiência da alimentação de fêmeas de jundiá com diferentes fontes lipídicas no desenvolvimento embrionário e larval. Foram utilizadas 12 fêmeas de jundiá (peso inicial de 500g), distribuídas ao acaso em três tanques-rede (1m³), alimentadas durante 10 semanas. Foram utilizados três dietas contendo como fontes lipídicas: banha suína (BS), óleo de girassol (OG), óleo de canola (OC). No momento da eclosão, foram coletadas nas incubadoras amostras de dez (10) larvas. Uma amostra de pós-larvas foi coletada às 12, 24, 36 e 48 horas pós-eclosão para medição. Mais três amostras de pós-larvas de cada incubadora foram capturadas e criadas durante 14 dias (30 larvas L-1). O desempenho das fêmeas e o desenvolvimento larval não foram afetados pelas fontes lipídicas testadas. Conclui-se que a banha suína é tão eficiente quanto óleo de girassol e canola como fontes lipídicas para fêmeas reprodutoras de jundiá e proporcionam bom desenvolvimento embrionário e larval.

The aim of this study was to evaluate the efficiency of feeding female South America catfish Rhamdia quelen with different lipids sources and their influence in embryo and larval stage. Twelve (12) female catfishes initial weight of 500g, distributed randomly among three (3) net-tanks and fed for ten (10) weeks were used. The female fishes were fed with three (3) different types of experimental diet containing lipid sources: Swine fat (BS), sunflower oil (OG) canola oil (OC). At hatch time, 10 larvae were collected from each net tank. One post larvae sample was collected at 12, 24, 36, 48 hours after hatch to verify measurement. Three samples were captured and raised in reuse water system during fourteen days (30 larvae L-1). The female reproductive performance and the larval development were not affected by the lipid sources tested. The data revealed that swine fat is as good as sunflower and canola oil as lipid sources for reproductive female catfishes and that they can provide excellent embryo and larval development.

Juvenis de carpa capim alimentados com capim teosinto e suplementados com diferentes taxas de arraçoamento / Grass carp juveniles fed with teosinte grass and supplied with different feeding rates

Avaliou-se o desenvolvimento de juvenis de carpa capim (Ctenopharyngodon idella) alimentados com capim teosinto (Euchlaena mexicana) e suplementados com ração. Realizaram-se dois experimentos, de 45 dias, utilizando 240 juvenis em cada um (peso médio: 10,9±0,3g e 20,2±0,2g). No experimento 1, os peixes foram alimentados com capim teosinto mais ração, em 4 níveis de suplementação: 1, 2, 3 e 4 por cento do PV, denominados S1, S2, S3 e S4. No experimento 2, testou-se: C=Somente Capim Teosinto; SD=Capim Teosinto+ Suplementação diária (3 por centoPV); SA=Capim Teosinto + Suplementação a cada dois dias (3 por centoPV); R=Somente ração (3 por cento PV). No experimento 1, observou-se aumento linear positivo do peso em relação à suplementação com ração. A melhor taxa de crescimento específico foi obtida com o tratamento S4. O rendimento de filé foi maior nos tratamentos S3 e S4. No experimento 2, para a variável peso, o tratamento SD diferiu significativamente dos demais. Os tratamentos SD, SA e R não diferiram estatisticamente em relação ao rendimento de filé, porém, houve diferença entre o tratamento SD e o C. Conclui-se que a associação do capim teosinto com a ração (3 por centoPV) proporciona bom crescimento para juvenis de carpa capim.

This study was aimed at evaluating the growth of grass carp juveniles (Ctenopharyngodon idella) fed with teosinte grass (Euchlaena mexicana) and supplied with different feeding rates. Two experiments were done (45 days each), using 240 juveniles (weight=10.33 ± 0.33 and 20.15 ± 0.23g). In the first, four feeding rates (1, 2, 3 and 4 percent of body weight (BW), called S1, S2, S3 and S4 respectively) were tested. In the second, the treatments were: C = Only teosinte grass; SD = Teosinte grass + ration daily (3 percentBW); SA = Teosinte grass + ration each 2 days (3 percentBW); R = Only ration (3 percentBW). In the experiment 1, it was observed a weight increasing following the ration supply. The higher specific growth rate was obtained in S4. No differences among treatments was verify for carcass yield, however, the fillet yield was higher in S3 and S4. In the experiment 2, weight was higher in SD. The carcass yield (RC) did not present significant difference among the treatments in the experiment 2. Fillet yield was lower in fish fed only with teosinte grass (C). We concluded that the grass carp juveniles growing is positively affected by association of teosinte grass and ration supply, being necessary a minimum feeding rate (3 percentBW) daily for achieving good growth.