Ultrastructure of intracytoplasmic Rickettsia-like infection of the gills of the teleost Archosargus probatocephalus (Sparidae) in northeastern Brazil / Ultraestrutura de Rickettsia intracitoplasmática infectando as brânquias do teleósteo Archosargus probatocephalus (Sparidae) no Nordeste do Brasil

Abstract A histopathological survey was conducted to investigate the presence of microparasites in fish Archosargus probatocephalus in a river near Maceió, Brazil. Light microscope observations of fragments of gill showed the presence of small cysts containing numerous myxospores that were morphologically identified as Henneguya. Transmission electron microscopy observations further revealed several gill cells containing groups of prokaryotic cells within large cytoplasmic vacuoles. Each infected host cell displayed a single vacuole containing a variable number of Rickettsia-like cells (up to 11), some of which presented the dumbbell shape characteristic of binary fission. The Rickettsia-like cells were pleomorphic, without a nucleus and with chromatin dispersed in the cytoplasm. They had a thin electron-dense wall of Gram-negative type. The morphology of these prokaryotic was similar to those of the order Rickettsiales and was described as a Rickettsia-like organism. Histopathological evaluation showed that several vacuole membranes had a lysed appearance. Some had ruptured, thus allowing direct contact between the Rickettsia-like organism and the cytoplasm of the host cell. The rupturing of the branchial epithelium may have contributed towards reduction of the surface area of the gills, but it is not possible to say that this was the cause of the host's death.

Resumo Um levantamento histopatológico foi realizado para pesquisar a presença de microparasitas, no peixe Archosargus probatocephalus, em um rio próximo a Maceió, Brasil. Observações ao microscópio óptico de fragmentos de brânquias mostraram a presença de pequenos cistos contendo numerosos mixósporos, identificados morfologicamente como Henneguya. Ocasionalmente, na microscopia eletrônica de transmissão, foram observados vários corpos citoplasmáticos de inclusão, grupo aparentemente de células procarióticas que vivem dentro de um grande vacúolo citoplasmático de algumas células branquiais. As células hospedeiras infectadas tinham um único vacúolo contendo um número variável de células do tipo Rickettsia, até 11, algumas das quais em forma do haltere, característica da fissão binária. Essas células eram pleomórficas sem núcleo, tendo a cromatina dispersa no citoplasma e possuíam uma parede densa de elétrons finos do tipo Gram-negativo. A morfologia dessas células procarióticas foi semelhante àquelas da ordem Rickettsiales e foram descritas como organismos tipo Rickettsiae. A histopatologia mostra várias membranas de vacúolos circundantes com aspetos lisados, enquanto outras apresentam rupturas que mostram contato direto do organismos tipo Rickettsiae com o citoplasma da célula hospedeira. A ruptura do epitélio branquial pode ter contribuído para a redução da superfície das brânquias, mas não é possível afirmar que foi a causa da morte do hospedeiro.

Bioactive endophytic fungi isolated from Caesalpinia echinata Lam. (Brazilwood) and identification of beauvericin as a trypanocidal metabolite from Fusarium sp.

Aiming to identify new sources of bioactive secondary metabolites, we isolated 82 endophytic fungi from stems and barks of the native Brazilian tree Caesalpinia echinata Lam. (Fabaceae). We tested their ethyl acetate extracts in several in vitro assays. The organic extracts from three isolates showed antibacterial activity against Staphylococcus aureus and Escherichia coli [minimal inhibitory concentration (MIC) 32-64 μg/mL]. One isolate inhibited the growth of Salmonella typhimurium (MIC 64 μg/mL) and two isolates inhibited the growth of Klebsiella oxytoca (MIC 64 μg/mL), Candida albicans and Candida tropicalis (MIC 64-128 μg/mL). Fourteen extracts at a concentration of 20 μg/mL showed antitumour activities against human breast cancer and human renal cancer cells, while two isolates showed anti-tumour activities against human melanoma cancer cells. Six extracts were able to reduce the proliferation of human peripheral blood mononuclear cells, indicating some degree of selective toxicity. Four isolates were able to inhibit Leishmania (Leishmania) amazonensis and one isolate inhibited Trypanosoma cruzi by at least 40% at 20 μg/mL. The trypanocidal extract obtained from Fusarium sp. [KF611679] culture was subjected to bioguided fractionation, which revealed beauvericin as the compound responsible for the observed toxicity of Fusarium sp. to T. cruzi. This depsipeptide showed a half maximal inhibitory concentration of 1.9 μg/mL (2.43 μM) in a T. cruzi cellular culture assay.

Biological characteristics and probiotic effect of Leuconostoc lactis strain isolated from the intestine of black porgy fish

A strain of lactic acid bacteria, Leuconostoc lactis, was isolated from the intestinal tract of black porgy, Sparus macrocephalus, and identified by conventional biochemical characteristics and 16S rDNA gene sequence analysis. The isolated strain had the ability of bile tolerance and resistance to low pH, and survived well in the trypsinase and pepsin solution. But the highly concentrated dose of trypsinase and pepsin affect the viability of the isolated strain. The isolate was resistant to several antibiotics, including Cephalothin, Ceftriaxone, Imipenem and Tobramycin. The isolate could autoaggregate itself and coaggregate with other bacteria in vitro. The autoaggregation percentage increased to 23.29% after 20 h of incubation. The percentage of coaggregation were respectively 31.21%, 29.44%, 10.74%, 16.49%, 24.36%, 24.41% and 20.99% for Vibrio parahaemolyticus, Listeria monocytogenes, Escherichia coli O157, Salmonella typhimurium, Shigella, Staphylococcus aureus and Proteusbacillus vulgaris after 20 h incubation of a mixed suspension. The supernatant of the strain inhibited the growth of several pathogens, such as V.parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Staphylococcus aureus, Escherichia coli O157, Salmonella typhimurium, Bacillus subtilis, Proteusbacillus vulgaris and Shigella. These results indicated that the isolate, Leuconostoc lactis, might be an attractive candidate for perspectival strain for probiotics in marine aquaculture.

Carga bacteriana de los peces Cynoscion squamipinnis (Perciformes: Scianidae) y Lutjanus gutattus (Perciformes: Lutjanidae) en la cadena de comercialización, Costa Rica

Bacteriological load of the fishes Cynoscion squamipinnis and Lutjanus gutattus in the marketing chain, Costa Rica. To determine the bacteriological quality of fishery products in the different stages from commercialization, monthly samples were taken during March 2004 and February 2006 from a Costa Rica marketing chain. Microbiological analyses were made to determine total coliforms (CT), faecal coliforms (CF), Escherichia coli (EC), aerobic total count (RTA), Salmonella sp., Staphylococcus aureus, Vibrio cholerae and Vibrio parahaemolyticus. Three body zones were analyzed: skin, belly and muscle. There were differences in the amount of CT between parts: skin had the highest counts, 11% of samples were identified as E. coli. and 2.5% of total counts were higher than the legal limit. Only 1.3% of the samples were S. aureus-positive. Salmonella sp., V. cholerae and V. parahaemolyticus were absent. Rev. Biol. Trop. 57 (1-2): 45-52. Epub 2009 June 30.

Con el fin de determinar la calidad bacteriológica de los productos pesqueros en las diferentes etapas de comercialización, desde marzo del 2004 y hasta febrero del 2006, recolectamos muestras mensuales y realizamos análisis microbiológicos para determinar coliformes totales (CT), coliformes fecales (CF), Escherichia coli, recuento total aerobio (RTA), Salmonella sp., Staphylococcus aureus, Vibrio cholerae y Vibrio parahaemolyticus en la piel, el vientre y la carne de los productos. Hubo diferencias en la cantidad de CT encontrada entre las diferentes zonas corporales muestreadas, siendo la piel la zona con mayor conteo. En el 11% de las muestras identificamos E. coli y el 2.5% de los recuentos totales superaron los límites máximos aceptados. Salmonella sp., V. cholerae y V. parahaemolyticus estuvieron ausentes, mientras que sólo el 1.3% de las muestras fueron positivas para S. aureus.

Efeitos da embalagem em atmosfera modificada sobre as alterações microbiológicas, químicas e sensoriais de pargo (Pagrus pagrus) / Effects of modified atmosphere packaging on microbiological, chemical and sensory changes of pargo (Pagrus pagrus)

Para avaliar os efeitos da embalagem em atmosfera modificada na vida útil do pargo (Pagrus pagrus), 20 amostras foramsubmetidas a quatro diferentes tratamentos: 100 por cento ar, 100 por cento CO2, 100 por cento N2, e 50/50 CO2/N2. Durante os 16 dias de estocagemforam coletadas amostras para contagem total de bactérias heterotróficas aeróbias mesófilas (CTBHAM), pH e avaliaçãosensorial de cor e odor. Os resultados obtidos foram organizados em tabelas e gráficos para realização de uma análiseestatística descritiva. O crescimento bacteriano foi mais acelerado, respectivamente, nas amostras embaladas em 100 por cento N2 e 50/50 CO2/N2, sendo os menores crescimentos observados nas embaladas em 100 por cento CO2. As amostras emaerobiose apresentaram um aumento do pH, atingindo um máximo de 7,07 no 8o dia de estocagem, assim como as amostrasembaladas em 100 por cento N2 atingiram um valor máximo de 7,49 no 16o dia. Os aspectos sensoriais da degradação foramprimeiramente observados no ar e mais tardiamente em 100 por cento CO2. Pode-se concluir que a embalagem contendo 100 por cento CO2se destacou das demais, mostrando bom desempenho na preservação da carne de pargo, aumentando sua vida útil e sendoa mais eficiente na manutenção dos parâmetros de qualidade.

For evaluate the effects of modified-atmosphere packaging on the shelf-life of pargo (Pagrus pagrus), 20 samples weresubmitted to 4 treatments: 100 percent air, 100 percent CO2, 100 percent N2, and 50/50 CO2/N2. During the 16 days of storage, samples werecollected to determine total viable count (TVC), pH and sensory evaluation of color and odor. The results obtained were arrangedin tables and grafics so as to make the analysis descriptive statistics. In the results was found a most quickly bacteria grew inpargo stored in 100 percent air, followed by those in 100 percent N2 and 50/50 percent CO2/N2 respectively, and the lowest counts were with 100 percentCO2. The samples packed under aerobiosis showed an increase in their pH, reaching a maximum of 7,07 on the 8th day, as wellthe samples packed in 100 percent N2 which had a maximum of 7,49 on the 16th day. Sensory aspects of degradation were earlierfound in air and latter in 100 percent CO2. According to the results, it can be concluded that the 100 percent CO2 packing stood out in relationto the others, showing good performance preserving pargo meat, extending shelf-life, being effective in keeping the qualityparameters.

Studies on saprolegniasis among cultured mullet fingerlings

In this work, two mullet species, Mugil cephalus and Mugil capito fingerlings naturally infected with saprolegnia were examined and controlled. Saprolegnia parasitica was isolated from the characteristic brownish cotton wool like lesions covering the body surface and penetrating into some internal organs. The infection trials with isolated Saprolegnia parasitica in apparently healthy mullet spp. via skin scarification revealed the same clinical signs and postmortem lesions. For controlling this serious disease, proper management and treatment by bathing the diseased mullet fingerlings in sodium chloride solution were used