RESUMO
In shrimp aquaculture, reduction in the use of synthetic antibiotics is a priority due to the high incidence of resistant bacteria (Vibrio) in the white shrimp Litopenaeus vannamei. An increasing number of studies show bactericidal activity of natural treatments in aquaculture. The effectiveness of neem (Azadirachta indica) and oregano (Lippia berlandieri) aqueous extracts and colloidal silver against V. parahaemolyticus were evaluated in low salinity shrimp culture. Results show that aqueous extracts of oregano and neem each present a minimum inhibitory concentration (MIC) of 62.50 mg ml-1 and inhibitory halos of 12.0 to 19.0 mm. Colloidal silver gave a MIC of 2 mg ml-1, and the inhibitory halos were found to be between 11.8 and 18.8 mm, depending on treatment concentrations. An in vivo challenge test was conducted on white shrimp postlarvae cultured at low salinity (5 practical salinity units, PSU), and a significant increase (p < 0.05) in survival was demonstrated in the presence of the aqueous extracts (oregano 64%, neem 76% and colloidal silver 90%), when compared to the control (0%) in the challenge test. However, no significant differences were observed between treatments, suggesting that they all act as alternative bactericidal source agents against V. parahaemolyticus infections for L. vannamei postlarvae when cultured at 5 PSU.
Assuntos
Lippia/química , Penaeidae/microbiologia , Plantas Medicinais , Prata/farmacologia , Vibrio parahaemolyticus/fisiologia , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Aquicultura/métodos , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Extratos Vegetais , SalinidadeRESUMO
El pargo colorado (Lutjanus colorado) es una especie con un alto valor comercial en el mercado mexicano, con potencial para su cultivo. Hasta la fecha no existen estudios sobre su reproducción, cultivo larvario y engorda en cautiverio. El presente trabajo es el primer reporte sobre la descripción a detalle del desarrollo embrionario de la especie bajo condiciones de cultivo. Los huevos fertilizados viables del pargo colorado son pelágicos, esféricos, transparentes y con una sola gota de aceite. Midieron 0,77±0,09 mm de diámetro y la gota de aceite 0,14±0,01 mm. La primera división ocurrió a las 0,05 horas post fertilización (HPF). La eclosión se llevó a cabo a las 17,22 HPF bajo las condiciones del presente estudio. Las larvas recién eclosionadas midieron 1,8±0,1 mm de longitud total (LT). El desarrollo embrionario de esta especie fue similar a la descrita para especies de la misma familia. Los resultados del presente estudio aportan información básica para iniciar el desarrollo de la biotecnología para la producción de semilla de esta especie a escala comercial.
The Colorado snapper (Lutjanus colorado) is one of the most commercially important fish species in México and it is considered a suitable candidate for culture. Until now, no research has been carried out on its reproduction, larviculture and fattening in captivity. This study is the first description of embryonic development of this species under controlled conditions. Fertilized eggs of Colorado snapper are pelagic, spherical and transparent and contain one drop of oil. Eggs measured 0.77±0.09 mm and the drop of oil 0.14±0.01 mm. First cell division occurred at 0.05 h post-fertilization (HPF), hatching at 17.22 HPF under the above described conditions. Larvae total length (LT) was 1.8±0.1 mm. Embryonic development of this species was similar to other lutjanidae species. These results provide basic information for developing the necessary biotechnology for commercial seed production of the Colorado snapper.
Assuntos
Animais , Óvulo , Perciformes/embriologia , Larva/crescimento & desenvolvimento , Perciformes/crescimento & desenvolvimento , Blástula/embriologia , Organogênese , Desenvolvimento Embrionário , Embrião não Mamífero , Gástrula/embriologiaRESUMO
The bullseye puffer is a marine fish species with great potential for aquaculture in Mexico, and the understanding of its reproductive physiology at every level of biological organization is essential in order to succeed. Several molecules orchestrate the complex process of oocyte maturation and spawning. One of these molecules is cyclin B, which is the regulatory subunit of the maturation-promoting factor. In this study, a fragment of the cyclin B gene was isolated from the ovary of the bullseye puffer using an RT-PCR approach. The gene fragment was homologous to the cyclin B2 gene of other vertebrate species. Similar levels of cyclin B gene expression were detected in ovaries at different developmental stages, except for atretic ovaries from captive fish which did not spawn. However, cyclin B gene expression was maintained in captive fish treated with LHRH-a to induce spawning, and appeared to be similar to the pattern observed in wild fish. It is possible that the reduced expression of cyclin B in atretic ovaries is the result of mRNA degradation during atresia. Alternatively, reduced gene expression could be a controlling factor in the process of oocyte reabsorption since cyclin B is required for final oocyte maturation and ovulation.