Tratamento de queimaduras de segundo grau profundo em abdômen, coxas e genitália: uso da pele de tilápia como um xenoenxerto / Treatment of deep second-degree burns on the abdomen, thighs, and genitalia: use of tilapia skin as a xenograft

A pele de tilápia possui microbiota não infecciosa e estrutura morfológica semelhante à pele humana. Estudos clínicos fase II, ainda não publicados, mostraram resultados promissores na sua utilização para tratamento de queimaduras. Nos protocolos destes estudos, pacientes com lesões em áreas de dobras de pele, como genitais e região inguinal, foram excluídos, pois achava-se que o biomaterial não aderiria apropriadamente, resultando em um grau de cicatrização inferior. Relato de caso de paciente do sexo feminino, 18 anos, sem comorbidades, com queimaduras de segundo grau profundo em abdômen, região inguinal, parte da genitália e metade superior de ambas as coxas, envolvendo 13,5% da área total da superfície corporal. A pele de tilápia foi aplicada nas lesões levando a uma reepitelização completa com 16 dias de tratamento. Não foram observados efeitos colaterais. A pele de tilápia traz, portanto, a promessa de um produto inovador, de fácil aplicação e alta disponibilidade, que pode se tornar a primeira pele animal nacionalmente estudada e registrada pela Agência Nacional de Vigilância Sanitária, para uso no tratamento de queimaduras. Este relato de caso contribui para reduzir as limitações em relação às áreas anatômicas apropriadas para a aplicação da pele de tilápia, uma vez que, mesmo com a necessidade de reposição de pele, foram obtidos bons resultados com aplicação na genitália e região inguinal.

Tilapia skin has a non-infectious microbiota and a morphological structure similar to human skin. Phase II clinical studies, not yet published, have shown promising results in their use for the treatment of burns. In the protocols of these studies, patients with lesions in areas of skin folds, such as genitals and inguinal regions, were excluded, as it was thought that the biomaterial would not adhere properly, resulting in a lower degree of healing. Case report of a female patient, 18 years old, without comorbidities, with deep second-degree burns in the abdomen, inguinal region, part of the genitalia and upper half of both thighs, involving 13.5% of the total body surface area. Tilapia skin was applied to the lesions leading to a complete re-epithelialization with 16 days of treatment. No side effects were observed. Tilapia skin, therefore, brings the promise of an innovative product, easy to apply, and highly available, which can become the first animal skin nationally studied and registered by the Agência Nacional de Vigilância Sanitária, for use in the treatment of burns. This case report contributes to reduce the limitations concerning the anatomical areas appropriate for the application of tilapia skin, since, even with the need for skin replacement, good results were obtained with application to the genitalia and inguinal region.

Anatomical and functional gonadotrope networks in the teleost pituitary.

Mammalian pituitaries exhibit a high degree of intercellular coordination; this enables them to mount large-scale coordinated responses to various physiological stimuli. This type of communication has not been adequately demonstrated in teleost pituitaries, which exhibit direct hypothalamic innervation and expression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in distinct cell types. We found that in two fish species, namely tilapia and zebrafish, LH cells exhibit close cell-cell contacts and form a continuous network throughout the gland. FSH cells were more loosely distributed but maintained some degree of cell-cell contact by virtue of cytoplasmic processes. These anatomical differences also manifest themselves at the functional level as evidenced by the effect of gap-junction uncouplers on gonadotropin release. These substances abolished the LH response to gonadotropin-releasing hormone stimulation but did not affect the FSH response to the same stimuli. Dye transfer between neighboring LH cells provides further evidence for functional coupling. The two gonadotropins were also found to be differently packaged within their corresponding cell types. Our findings highlight the evolutionary origin of pituitary cell networks and demonstrate how the different levels of cell-cell coordination within the LH and FSH cell populations are reflected in their distinct secretion patterns.

Chondrogenic differentiation of human mesenchymal stem cells on fish scale collagen.

Fish collagen has recently been reported to be a novel biomaterial for cell and tissue culture as an alternative to conventional mammalian collagens such as bovine and porcine collagens. Fish collagen could overcome the risk of zoonosis, such as from bovine spongiform encephalopathy. Among fish collagens, tilapia collagen, the denaturing temperature of which is near 37°C, is appropriate for cell and tissue culture. In this study, we investigated chondrogenic differentiation of human mesenchymal stem cells (hMSCs) cultured on tilapia scale collagen fibrils compared with porcine collagen and non-coated dishes. The collagen fibrils were observed using a scanning electronic microscope. Safranin O staining, glycosaminoglycans (GAG) expression, and real-time PCR were examined to evaluate chondrogenesis of hMSCs on each type of collagen fibril. The results showed that hMSCs cultured on tilapia scale collagen showed stronger Safranin O staining and higher GAG expression at day 6. Results of real-time PCR indicated that hMSCs cultured on tilapia collagen showed earlier SOX9 expression on day 4 and higher AGGRECAN and COLLAGEN II expression on day 6 compared with on porcine collagen and non-coated dishes. Furthermore, low mRNA levels of bone gamma-carboxyglutamate, a specific marker of osteogenesis, showed that tilapia collagen fibrils specifically enhanced chondrogenic differentiation of hMSCs in chondrogenic medium, as well as porcine collagen. Accordingly, tilapia scale collagen may provide an appropriate collagen source for hMSC chondrogenesis in vitro.

Stock assessment of fishery target species in Lake Koka, Ethiopia / Evaluación de las reservas pesqueras de especies objetivo en el lago Koka, Etiopia

Effective management is essential for small-scale fisheries to continue providing food and livelihoods for households, particularly in developing countries where other options are often limited. Studies on the population dynamics and stock assessment on fishery target species are thus imperative to sustain their fisheries and the benefits for the society. In Lake Koka (Ethiopia), very little is known about the vital population parameters and exploitation status of the fishery target species: tilapia Oreochromis niloticus,common carp Cyprinus carpióand catfish Clarias gariepinus.Our study, therefore, aimed at determining the vital population parameters and assessing the status of these target species in Lake Koka using length frequency data collected quarterly from commercial catches from 2007-2012. A total of 20 097 fish specimens (distributed as 7 933 tilapia, 6 025 catfish and 6 139 common carp) were measured for the analysis. Von Bertalanffy growth parameters and their confidence intervals were determined from modal progression analysis using ELEFAN I and applying the jackknife technique. Mortality parameters were determined from length-converted catch curves and empirical models. The exploitation status of these target species were then assessed by computing exploitation rates (E) from mortality parameters as well as from size indicators i.e., assessing the size distribution of fish catches relative to the size at maturity (L m),the size that provides maximum cohort biomass (Lopt) and the abundance of mega-spawners. The mean value of growth parameters L x, Kand the growth performance index 0' were 44.5 cm, 0.41/year and 2.90 for O. niloticus,74.1 cm, 0.28/year and 3.19 for C. carpioand 121.9 cm, 0.16/year and 3.36 for C. gariepinus,respectively. The 95 % confidence intervals of the estimates were also computed. Total mortality (Z) estimates were 1.47, 0.83 and 0.72/year for O. niloticus, C. carpioand C. gariepinus,respectively. Our study suggest that O. niloticusis in a healthy state, while C. gariepinusshow signs of growth overfishing (when both exploitation rate (E)and size indicators were considered). In case of C. carpio,the low exploitation rate encountered would point to underfishing, while the size indicators of the catches would suggest that too small fish are harvested leading to growth overfishing. We concluded that fisheries production in Lake Koka could be enhanced by increasing Etoward optimum level of exploitation (E opt)for the underexploited C. carpioand by increasing the size at first capture (Lc)toward the L opt range for all target species.

Un manejo pesquero eficiente es fundamental para que las pesquerías artesanales puedan continuar proveyendo alimento y sustento para los hogares, particularmente en los países en vía de desarrollo, en donde otras opciones a menudo son limitadas. Estudios sobre la dinámica poblacional de las especies objetivo de las pesquerías son, por lo tanto, imperativos para mantener las pesquerías y los beneficios para las sociedades. Esto también es válido para los recursos del Lago Koka (Etiopia) en donde hasta ahora se sabe muy poco sobre los parámetros poblacionales vitales y el estatus de las especies objetivo como la tilapia Oreochromis niloticus,la carpa Cyprinus carpioy el bagre Clarias gariepinus.El estudio aquí presentado tiene como objetivo determinar estos parámetros y evaluar el estado de la pesquería de estas especies en el lago Koka, utilizando los datos de frecuencia de tallas obtenidas de capturas trimestrales en el periodo 2007-2012. Un total de 20 097 especímenes fueron medidos (7 933 de tilapia, 6 025 de bagre y 6 139 de carpa). Los parámetros de crecimiento de von Bertalanffy fueron derivados del análisis de progresión de las modas usando ELEFAN I y aplicando la técnica de jackknife. Las tasas de mortalidad fueron estimadas de curvas de capturas basadas en longitudes y usando modelos empíricos. La tasa de explotación (E), se estimó con los parámetros de mortalidad y también considerando indicadores del tamaño a través de la distribución de tallas en las capturas y su relación con la talla de la primera madurez (L m),el tamaño que provee la biomasa máxima del cohorte (L opt)y la abundancia de los "mega-desovantes". Los valores calculados para los parámetros de crecimiento L m, Ky el índice de la capacidad de crecimiento 0' fueron: 44.5 cm, 0.41 año-1 y 2.90 para O. niloticus,74.1 cm, 0.28 año-1 y 3.19 para C. carpióy 121.9 cm, 0.16 año-1 y 3.36 para C. gariepinus,respectivamente. La tasa de mortalidad total (Z) fue estimada en 1.47, 0.83 y 0.72 año-1 para O. niloticus, C. carpioand C. gariepinus,respectivamente. Nuestros resultados sugieren que la población de O. niloticusse encuentra en un estado saludable, mientras C. gariepinusya muestra signos de sobrepesca por crecimiento. En el caso de C. carpiolas tasas de explotación tan bajas (E<0.5) que se encontraron, pueden apuntar a una sub-explotación, mientras que los indicadores de tallas sugieren que las pequeñas tallas obtenidas, pueden conducir a una sobrepesca por crecimiento. Concluimos que la producción pesquera en el lago Koka puede ser mejorada si se incrementa E al nivel E opt para C. carpioy aumenta el tamaño de la primera captura (Lc)al rango de L opt para todas las especies objetivo.

Acute exposure to pure cylindrospermopsin results in oxidative stress and pathological alterations in tilapia (Oreochromis niloticus).

Cylindrospermopsin (CYN) is increasingly recognized as a potential threat to drinking water safety, due to its ubiquity. This cyanotoxin has been found to cause toxic effects in mammals, and although fish could be in contact with this toxin, acute toxicity studies on fish are nonexistent. This is the first study showing that single doses of CYN pure standard (200 or 400 µg CYN/kg fish bw) by oral route (gavage) generate histopathological effects in fish (Tilapia-Oreochromis niloticus) exposed to the toxin under laboratory condition. Among the morphological changes, disorganized parenchymal architecture in the liver, dilated Bowman's space in the kidney, fibrolysis in the heart, necrotic enteritis in the intestines, and hemorrhages in the gills, were observed. Moreover, some oxidative stress biomarkers in the liver and kidney of tilapias were altered. Thus, CYN exposure induced increased protein oxidation products in both organs, NADPH oxidase activity was significantly increased with the kidney being the most affected organ, and decreased GSH contents were also detected in both organs, at the higher dose assayed.

Biochemical and cellularchanges in Oreochromis niloticus related to the water pollution of a degraded river / Alterações bioquímicas e celulares em Oreochromis niloticus relacionadas com a poluição da água de um rio degradado

The effects of polluted water at three sites in the Marinho River, Brazil, on Oreochromis niloticus (Nile tilápia) were investigated using histological, hematological and biochemical approaches. Fish exposed to the impacted water demonstrated that histological changes in gills were accompanied by nuclear and micronuclei abnormalities in cells. The activity of liver and plasma biomarkers (alkaline phosphatase (ALP), acid phosphatase (ACP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and liver glutathione S-transferase (GST)) showed an expressive change due to the. The results were also correlated with the highest levels of Cu+2, Zn+2 and Mn+2 in the water. The data of this study evidenced the importance of using a set of biomarkers to quantify pollution in lentic ecosystems. Additionally, histological analyses of gills and erythrocytes have proven to be an important instrument for signaling the impact of pollutants in rivers.

Os efeitos da poluição da água de três locais do Rio Marinho, Brasil, em Oreochromis niloticus foram investigados usando técnicas histológicas, hematológicas e bioquímicas. Peixes expostos à água impactada demonstraram que alterações histológicas nas brânquias foram acompanhadas de anomalias nucleares e micronúcleo nas células. A determinação da atividade de biomarcadores em fígado e plasma de tilápia (fosfatase alcalina (ALP), fosfatase ácida (ACP), alanina aminotransferase (ALT), aspartato aminotransferase (AST) e glutationa S-transferase (GST)) mostrou uma substancial alteração em função da poluição. Os resultados são correlacionados com os níveis mais elevados de Cu+2, Zn+2 e Mn+2 na água. Os dados deste estudo demonstram a importância de utilizar um conjunto de biomarcadores para quantificar a poluição em ecossistemas lênticos. Adicionalmente, as análises histológicas das brânquias e de eritrocitos têm provado ser importante instrumento para sinalizar a impactação de poluentes ao longo de rios.

Edad y crecimiento del híbrido de tilapia Oreochromis niloticus x Oreochromis aureus (Perciformes: Cichlidae) en la represa “Zimapán” Hidalgo, México

Age and growth of the hybrid tilapia Oreochromis niloticus x Oreochromis aureus (Perciformes: Cichlidae) in the dam “Zimapan” Mexico. Studies on age and growth in fishes are essential to establish models on population dynamics. The previos issues were determined in this study by scale growth analyses. Between September 2003 and May 2004, 382 organisms were captured using gill and atarraya nets. Eight samples were developed every month a long this study. Standard length in centimeters (Le), total weight in grams (Pt), scale length in centimeters (Lesc) and growth rings were determined. The size and weight ranged from 38 to 232mm (Le) and 8.7 to 311.9g (Pt), respectively. The growth rings analyses reveal four age groups, being the sec-ond group the most representative with 34.3% of the total sampled. The scale ring analyses showed two growth rings, one develops between November-January and the other between April-May, in good correlation with low temperature and gonad development, respectively. The growth parameters were established as: L∞=281.1mm, W∞=877.1g, K=0.33 and T0=0.88year -1. The growth curves based on length and weight were described by using the von Bertalanffy model: Le =28.11[1-e-0.33(t+0.88)] and Pt =877.17[1-e-0.33(t+0.88)]³. Finally, it is concluded that commercial catches in this dam are between a year and year and half-old when exploited. Rev. Biol. Trop. 59 (2): 761-770. Epub 2011 June 01.

La edad y crecimiento de la tilapia Oreochromis niloticus x Oreochromis aureus fueron determinados por medio de la lectura de escamas. Un total de 382 individuos fueron capturados mediante el uso de redes agalleras y atarrayas. Ocho recolectas mensuales se llevaron a cabo entre septiembre 2003-mayo 2004; se registraron los datos de longitud estándar en cm. (Le), el peso total en g (Pt) y se obtuvieron muestras de escamas para registrar el largo de la escama en mm. (Lesc) y el número de anillos de crecimiento formados. Las tallas y pesos de recolecta variaron entre 38 a 232mm (Le) y de 8.7 a 311.9g de peso total (Pt) respectivamente. El recuento de los anillos anuales en escamas, permitió establecer cuatro grupos de edad, siendo el grupo de edad 2 el más representativo, con un 34.3% de la población muestreada. El cálculo de los incrementos marginales del crecimiento mensual de las escamas, sugirió la formación de dos anillos, uno de ellos se forma en los meses de noviembre-enero y otro en los meses de abril-mayo, los cuales coinciden con la época de bajas temperaturas y de madurez gonádica respectivamente. Los parámetros de crecimiento quedaron establecidos en: L∞=281.1mm, W∞=877.1g, K=0.33 y T0=0.88/año. Las curvas de crecimiento en longitud y peso se describieron mediante las ecuaciones de von Bertalanffy: Le=28.11 [1- e-0.33(t+0.88)] y Pt=877.17 [1-e-0.33(t+0.88)]³. Finalmente, se concluyó que los peces que se explotan en la represa mediante captura comercial presentan entre un año y año y medio de edad.

Testes físico-mecânicos e físico-químicos do couro da tilápia vermelha / Physical-mechanical and physical-chemical tests of red tilapia leather

Realizaram-se testes físico-mecânicos e físico-químicos em couro de tilápia vermelha (Oreochromis spp.) a fim de testar a sua resistência. As amostras foram distribuídas em delineamento inteiramente ao acaso com dois tratamentos: no T1, procedeu-se à retirada do corpo-de-prova no sentido longitudinal e, no T2, à retirada do corpo-de-prova no sentido transversal. Para os testes de determinação da resistência à tração, alongamento e rasgamento progressivo, foi utilizado o dinamômetro EMIC, com velocidade de afastamento entre as cargas de 100 ± 20mm/min, em ambiente climatizado (± 23ºC e UR do ar de 50 por cento), por 24 horas. A espessura do couro variou de 0,61 a 0,75mm, mas não houve diferença entre os sentidos analisados. O couro apresentou maior resistência à tração no sentido transversal, 25,89N/mm², (P<0,01), comparado ao sentido longitudinal, 14,20 N/mm². O alongamento foi significativamente (P<0,05) maior no sentido longitudinal, 80,8 por cento, em relação ao transversal, 62,6 por cento. Não houve diferença para o rasgamento progressivo entre os tratamentos. O couro apresentou teor de óxido de cromo de 3,8 por cento, graxa de 15,1 por cento e pH e cifra diferencial de 3,5 e 0,5, respectivamente. Os valores nos testes de resistência e físico-químicos apresentados pelo couro indicam que ele pode ser utilizado para a confecção de vestuário e artefatos de couro em geral.

Physical-mechanical and physical-chemical tests were carried out on red tilapia leather. They were distributed in a completely randomized design with two treatments: T1 = longitudinal body of proof; T2 = transversal body of proof. It was used the EMIC dynamometer for the tests of resistance to traction and elongation and the progressive tearing, with the speed of 100±20mm/min away between the charges, in an acclimatized room (±23ºC and relative humidity of 50 percent) during 24 hours. The thickness of the analyzed leathers ranged from 0.61 to 0.75mm, without differing between the analyzed ways. The leather demonstrated a higher resistance to traction in the transversal direction (25.89N/mm²) (P<0.01), when compared to the longitudinal one (14.20N/mm²). However, the elongation was significantly higher (P<0.05) in the longitudinal direction (80.8 percent) when compared to the transversal (62.6 percent). There was no significant difference for the progressive tearing between the treatments (longitudinal = 18.56N/mm; transversal = 21.90N/mm). The leather demonstrated a content of 3.8 percent of chromium oxide, 15.1 percent of grease, and pH and difference value of 3.5 and 0.5, respectively. The values in the resistance and physical-chemical tests shown by the leather indicate that it may be used for clothing and leather artifacts in general.

Age and growth of the tilapia, Oreochromis niloticus (Perciformes: Cichlidae) from a tropical shallow lake in Mexico

Age and growth of Nile tilapia (Oreochromis niloticus) were determined using 1 039 specimens collected in a tropical shallow lake of Mexico, from January to December 1993. Standard length of females ranged from 9.0 to 16.5 cm and males from 8.9 to 14.8 cm. The standard length-weight relationships for all individuals was BW=0.1207 SL2.469. The age data, derived from opercular bone readings, were used to estimate the growth parameters of the von Bertalanffy equation: or = 17.88 cm, K=0.3409, t o=-1.543, and W=149.21 g. The oldest male and female were 2.5 years old. The sex ratio (female:male) was of 1:1 (X²=0.02, p>0.05). Rev. Biol. Trop. 56 (2): 875-884. Epub 2008 June 30.

Se determinó la edad y el crecimiento de la tilapia del Nilo (Oreochromis niloticus) utilizando 1 039 organismos que fueron recolectados de Enero a Diciembre de 1993 en un lago somero tropical de México. La talla para las hembras osciló entre 9.0 y 16.5 cm longitud patrón y para los machos entre 8.9 y 14.8 cm. La relación peso total-longitud patrón para toda la población fue P=0.1207 L2.469. Los datos de edad obtenidos a través de los anillos del hueso opercular se utilizaron para estimar los parámetros de crecimiento del modelo de von Bertalanffy: o = 17.88 cm, K=0.3409, t o=-1.543 y P o = 149.21 g. La edad máxima obtenida para hembras y machos fue de 2.5 año. La proporción sexual (hembra:macho) para la especie fue de 1:1 (X²=0.02, p>0.05).

Formation of ring marks in stocked tilapia juveniles (Oreochromis aureus/O. niloticus) (Perciformes: Cichlidae)

Lake Metztitlán was dried up completely in the spring of 1998 and refilled in August of that year. In the period September-November, two cohorts of 1.6 million juveniles of a tilapia hybrid were stocked (Oreochromis aureus/O. niloticus), and monitored every month for one year. Since the date of birth of these juveniles was known, the analyses focused on whether the ring marks of the scales, sagittae and opercula or the circuli of the scales could be used to age them. The ring marks of the scales and opercula showed great variability, and the sagittae had a significant relationship with length, but it is unclear if at least the first ring mark could be formed at the hatchery and reflect changes in diet and/or tank movements in the fish farm. The circuli had a continuous regular behavior, with a formation rate of 10.38±0.93 and 11.38±0.95 circuli/month for the first and second cohorts, respectively. This proportion was maintained during the study period, and could be of help to calculate an approximate age of juveniles, especially in stocked fish that show multiple ring marks because of manipulation in fish farms and stocking events. Rev. Biol. Trop. 55 (3-4): 1005-1013. Epub 2007 December, 28.

El lago de Metztitlán se secó completamente en la primavera de 1998, inundándose nuevamente en agosto del mismo año para ser repoblado entre septiembre y noviembre con 1.6 millones de jóvenes de un híbrido de tilapia (Oreochromis aureus/O. niloticus) en dos periodos. Ambas cohortes fueron monitoreadas mensualmente durante un año. Debido a que la fecha de nacimiento era conocida, el objetivo del estudio fue evaluar si las marcas anulares de las escamas, las sagittae y los opérculos, o los circuli de las escamas pueden usarse para estimar la edad. Los anillos de las escamas y opérculos mostraron gran variabilidad, mientras que las de las sagittae se relacionaron significativamente con la longitud, sin embargo no quedó claro si al menos el primer anillo podría haber sido formado por cambios en dieta o movimientos en los tanques de la granja de cultivo. Por el contrario los circuli mostraron una formación regular con una tasa de formación de 10.38±0.93 y 11.38±0.95 circuli/mes para la primera y segunda cohortes, respectivamente, proporción que fue mantenida durante el periodo de estudio y que puede ser usada para calcular la edad de los jóvenes, especialmente en organismos que muestran numerosos anillos debido a la manipulación sufrida en las granjas o debido a las "siembras".

Age-growth models for tilapia Oreochromis aureus (Perciformes, Cichlidae) of the Infiernillo reservoir, Mexico and reproductive behaviour

In presence of a decrease in the catch from Infiernillo reservoir, Michoacán-Guerrero, Mexico, age and growth of tilapia Oreochromis aureus (Steindachner 1864) were estimated, as indispensable attributes for fishery management. Evaluations included scales and opercular bones readings and length frequency analysis. The population structure was determined too. Due to the great variation of tilapia individual growth and with the objective to have reliable growth estimations, linearized, non-parametric and non-linear methods were used and their applicability discussed. Comparison of ages determined from these methods revealed that opercular bones readings had advantages over scales. Reproduction and competition for space and food were considered as responsible factors for ring-formation on tilapia hard structures. The non-linear method was considered the best for modelling populations highly variable, which is characteristic of tilapia and tropical fish with multiple spawns. The growth parameters estimated were Linfinity = 479 mm, K = 0.46/yr, t0 = -0.055 yr. The tilapia population in Infiernillo reservoir is dominated by juveniles less than 1.5 years old. The fishery activity is affecting the tilapia population growth because are caught when they have not yet spawned. Therefore, this fishery is in urgent need of regulation. Increasing the mesh size of the gill nets might contribute to protect the reproductive potential of the stock.

Ante el continuo decremento en las capturas de tilapia de la presa Infiernillo, Michoacán-Guerrero, México, se estimó la edad y crecimiento de Oreochromis aureus (Steindachner 1864) que son atributos indispensables que deben conocerse para realizar el manejo de la pesquería. La evaluación incluyó la lectura de marcas de crecimiento en escamas y opérculos, y el análisis de frecuencia de tallas. También se estimó la estructura de edad de la población. Debido a la alta variabilidad individual en el crecimiento que presentan las tilapias y a fin de obtener estimaciones fidedignas de crecimiento, diferentes métodos lineales, noparamétricos y no-lineales fueron usados y su aplicación discutida. Los opérculos presentaron ventajas sobre las escamas en la determinación de edad. La reproducción y la competencia por espacio y alimento fueron consideradas factores responsables de la formación de marcas en las estructuras duras de tilapia. El modelo no-lineal fue considerado el mejor para modelar el crecimiento de poblaciones altamente variables como la de tilapia y otros peces tropicales que presentan múltiples desoves. Los parámetros de crecimiento estimados fueron: L∞ = 479 mm, K = 0.46/yr, to = -0.055 yr. La población de tilapia en la presa Infiernillo está dominada por juveniles menores de año y medio de edad. La actividad pesquera está afectando el crecimiento de la población de tilapia, puesto que éstas son capturadas antes de que desoven. La pesquería requiere urgentemente una regulación. Un incremento en la abertura de malla de las redes agalleras con que es capturada, podría contribuir a proteger el potencial reproductivo del stock.

Localization of the three GnRH types and GnRH receptors in the brain of a cichlid fish: Insights into their neuroendocrine and neuromodulator functions.

The cognate receptor for any of the known gonadotropin-releasing hormones (GnRHs) has not been directly demonstrated. In order to establish this and shed light on the functions of GnRH types, we analyzed the neuroanatomical location and time of initial expression of three distinct GnRH receptors (GnRH-Rs) and the three endogenous GnRHs in the brain of developing and sexually mature tilapia Oreochromis niloticus using immunocytochemistry. In all age groups, including males and females, GnRH-RIA was seen specifically in gonadotropes (Parhar et al. [2002] J Neuroendocrinol 14:657-665) but was undetectable in the brain. On day 8 after fertilization, GnRH-RIB was first seen in the periventricular hypothalamus (lateral recess nucleus, posterior recess nucleus, posterior tuberal nucleus) and GnRH-RIII in the olfactory epithelium, olfactory bulb, telencephalon, preoptic region, mediobasal hypothalamus, thalamus, mesencephalon, and in the hindbrain. Double-label immunocytochemistry showed GnRH1 (Ser(8) GnRH)-immunoreactive neuronal processes projecting mainly to the proximal pars distalis of the pituitary, while GnRH2 (His(5), Trp(7), Tyr(8) GnRH) and GnRH3 (Trp(7), Leu(8) GnRH) fibers were observed in close association with cells containing GnRH-RIB and GnRH-RIII in the brain. These results suggest that GnRH-RIA might be hypophysiotropic in nature, whereas GnRH-RIB and GnRH-RIII could have additional neuromodulatory functions. Further, evidence of close proximity of GnRH-R-containing cells and neuronal processes of multiple GnRH types suggests complex cross-talk between several GnRH ligands and GnRH-Rs.

Morphological aspects of muscle regeneration in the Nile tilapia (Oreochromis niloticus).

The aim of our study was to analyze the morphological events in the skeletal muscle of the Nile tilapia (Oreochromis niloticus) after a traumatic lesion. Thirty-two fish were used, on which a small longitudinal incision was made in the muscle. The fish were sacrificed after 7, 14, 21, and 42 days and muscle samples were collected from the lesion and processed for morphological analysis. Muscle regeneration in the tilapia occurred gradually through the analyzed period, possibly due to the proliferation and differentiation of myosatellite cells, which were more morphologically evident 7 and 14 days after lesion.

Culture conditions affect induction of vitellogenin synthesis by estradiol-17 beta in primary cultures of tilapia hepatocytes.

In vitro synthesis of vitellogenin (VTG), a female-specific protein, after estradiol-17 beta (E(2)) treatment was compared among different culture conditions using the hepatocytes of tilapia, Oreochromis mossambicus. VTG was measured by enzyme-linked immunosorbent assay. Comparison of Leibovitz's L-15 medium (L-15), Williams' medium E (WE) and Medium 199 (M199), which have been used for hepatocyte cultures in certain teleost fishes, showed that monolayer formation of the hepatocytes on the plate in WE and M199 was faster than in L-15 at the beginning of the culture. Morphological differences in the hepatocytes among the culture media were not evident by 96 h after culture. VTG synthesis in L-15 after E(2) treatment was higher than in WE and M199. A concentration of NaHCO(3) at 5 mM in L-15 resulted in faster monolayer formation of the cells and higher VTG synthesis than at 0 and 23 mM. Primary culture of the tilapia hepatocytes at 28 degrees C showed higher synthesis of VTG than at 23 and 33 degrees C. These results suggest that nutritional requirements are vitally different among species, and there are optimal ranges in the pH and the temperature in cultured hepatocytes.

Histological study of the development of the embryo and early larva of Oreochromis niloticus (Pisces: Cichlidae).

The developmental stages of Oreochromis niloticus are similar to those described in other mouth-breeding tilapias except that, as in zebrafish, no cavity was found in the blastula. Variation in the rate of development of the embryo and larva of O. niloticus was found within a clutch of eggs as well as between clutches. Hatching glands are described for the first time in tilapias. They are widely distributed within the ectoderm covering the head, body, tail, and surface of the yolk sac near its attachment to the embryo. Timing of larval development is similar to that in other mouthbrooding tilapias, but is slower than that found in substrate-spawning tilapias. A pneumatic duct connects the swimbladder to the digestive tract and swimbladder inflation and initiation of feeding occurs at about the same time. The digestive tract of the larva 8 and 9 days after fertilization is similar to that found in the adult, except that there are no digestive glands. An endocrine pancreatic islet was first seen 76 h after fertilization. A prominent thymus gland is present at 100 h. Hematopoietic tissue develops in the vicinity of the pronephros during early larval development. A spleen develops later, 7 days after fertilization.

NaCl uptake by the branchial epithelium in freshwater teleost fish: an immunological approach to ion-transport protein localization.

Teleost fishes, living in fresh water, engage in active ion uptake to maintain ion homeostasis. Current models for NaCl uptake involve Na(+) uptake via an apical amiloride-sensitive epithelial Na(+) channel (ENaC), energized by an apical vacuolar-type proton pump (V-ATPase) or alternatively by an amiloride-sensitive Na(+)/H(+) exchange (NHE) protein, and apical Cl(-) uptake mediated by an electroneutral, SITS-sensitive Cl(-)/HCO(3-) anion-exchange protein. Using non-homologous antibodies, we have determined the cellular distributions of these ion-transport proteins to test the predicted models. Na(+)/K(+)-ATPase was used as a cellular marker for differentiating branchial epithelium mitochondria-rich (MR) cells from pavement cells. In both the freshwater tilapia (Oreochromis mossambicus) and rainbow trout (Oncorhynchus mykiss), V-ATPase and ENaC-like immunoreactivity co-localized to pavement cells, although apical labelling was also found in MR cells in the trout. In the freshwater tilapia, apical anion-exchanger-like immunoreactivity is found in the MR cells. Thus, a freshwater-type MR chloride cell exists in teleost fishes. The NHE-like immunoreactivity is associated with the accessory cell type and with a small population of pavement cells in tilapia.

Cortisol increases Na(+)/K(+)-ATPase density in plasma membranes of gill chloride cells in the freshwater tilapia Oreochromis mossambicus.

The effect of cortisol on Na(+)/K(+)-ATPase expression in the gill chloride cells of tilapia Oreochromis mossambicus was studied by immunocytochemistry at the light and electron microscope levels. One of three doses of cortisol (low, 125 mg kg(-1 )food; middle, 375 mg kg(-1 )food; high, 750 mg kg(-1) food) was administered via the food (at a ration of 1.5 % of body mass) and the fish were sampled after 5 days. Plasma osmolality and Na(+) levels were elevated in the middle- and high-dose groups, and plasma cortisol levels in the high-dose groups. Hematocrit values were not affected by the treatments. Opercular membrane chloride cell density increased by 94 % and 286 % in the middle- and high-dose fish, respectively, whereas the gill chloride cell frequency increased by up to 28 % maximally in the high-dose fish. Lamellar gill chloride cells were absent in the control and low-dose groups, but were observed in the middle- and high-dose groups. Cortisol increased the volume of the tubular membrane system in mature gill chloride cells. Quantification of immunogold-labelled Na(+)/K(+)-ATPase antigen (a 104 kDa protein species, as demonstrated by western blot) revealed that the high dose of cortisol increases the Na(+)/K(+)-ATPase density in the tubular system of chloride cells. This is the first direct evidence that cortisol not only increases chloride cell numbers but also Na(+)/K(+)-ATPase density in these cells.

Ultrastructure and distribution dynamics of chloride cells in tilapia larvae in fresh water and sea water.

Integumental and branchial chloride cells of tilapia larvae (Oreochromis mossambicus) were studied at the light-microscopical and ultrastructural level. Total numbers and distribution of chloride cells were quantified after immunostaining of cross sections of the entire larvae with an antibody against the alpha-subunit of Na+/K+-ATPase. The majority (66%) of Na+/K+-ATPase-immunoreactive (ir) cells, i.e. chloride cells, of freshwater tilapia larvae were located extrabranchially up to 48 h after hatching. Five days after hatching, the majority (80%) of chloride cells were found in the buccal cavity. Transfer of 24-h-old larvae to 20% sea water speeded up this process; 24 h after transfer (i.e. 48 h after hatching), the majority (59%) of chloride cells were located in the buccal cavity. The branchial chloride cell population of 24-h- and 120-h-old larvae consisted of immature, mature, apoptotic and necrotic chloride cells. However, relatively more immature chloride cells were observed in freshwater larvae (42-63%) than in (previously studied) freshwater adults (21%), illustrating the developmental state of the gills. After transfer to sea water, the incidence of degenerative chloride cells did not change. Furthermore, the incidence of immature cells had decreased and a new subtype of chloride cells, the "mitochondria-poor" cells, appeared more frequently. These mitochondria-poor chloride cells were characterised by an abundant tubular system and relatively few mitochondria, which were aligned at the border or concentrated in one part of the cytoplasm. Most of these cells did not contact the water. The function of their enhanced appearance after seawater transfer is unknown.

GnRH-systems in the forebrain of cichlid fish.

The neuronal systems that contain gonadotropin-releasing hormone (GnRH) were quantitatively examined in the forebrain of two cichlid species (Oreochromis niloticus Lin. and Tilapia maria Boulenger) using tracing methods and immunostaining. In both species the nucleus olfacto-retinalis and a population of neurons in the basal preoptic region contained GnRH. The nucleus olfacto-retinalis was divided into several neuronal subpopulations which differed with respect to cytology, projection pattern, and peptide content. GnRH cell number increased with body size, the rates being different for the different subpopulations. A sexual dimorphism was found in the basal preoptic region of Tilapia; males had significantly fewer GnRH-containing cells than females. Selective staining of the basal preoptic region demonstrated that this cell group is the main source of GnRH-innervation of the pituitary gland and indicate that the molecular forms of GnRH expressed in the two cell populations studied may be different.

Immunocytochemical characterization of the pancreatic islet cells of the Nile Tilapia (Oreochromis niloticus).

The cellular composition and topography of the pancreatic islet of Oreochromis niloticus, now known to be a donor source for islet xenotransplantation studies, were characterized. Whole tilapia islets were harvested using an enzymatic method and then further digested into single-cell preparations. Cell cytospin preparations of islet cells and paraffin sections of whole islets were stained using antisera against tilapia insulin, human glucagon, salmon somatostatin-25 (SST-25), human somatostatin-14 (SST-14), and salmon peptide tyrosine-tyrosine (PYY) using the immunoperoxidase method. Cell counts, performed on cytospin preparations using a Quantimet 570 computerized image analysis system, revealed that O. niloticus islets contained 78% endocrine cells and 22% immunonegative cells (i. e., mainly nucleated erythrocytes and rare tissue eosinophils). The proportions of immunopositive endocrine cell types were: 42.3% insulin immunopositive cells, 11.5% glucagon immunopositive cells, 23.1% SST-25 immunopositive cells, 21.8% SST-14 immunopositive cells, and 1.3% PYY immunopositive cells. Islet cell topography was evaluated using histologic sections of whole endocrine pancreata including large, medium, and small islets. Round to polygonal insulin immunopositive cells with round central nuclei were distributed in clusters throughout both the principal and the smaller islets. Elongate SST-14 immunopositive cells were closely associated with the clusters of insulin immunopositive cells; both were surrounded by SST-25 immunopositive cells, which were similar in shape to the insulin immunopositive cells. There were elongate glucagon immunopositive cells throughout the islets, whereas the PYY immunopositive cells were restricted to the periphery and to channels of fibrovascular connective tissue penetrating the islets.