Familiarity reduces aggression but does not modify acoustic communication in pairs of Nile tilapia (Oreochromis niloticus) and black-chinned tilapia (Sarotherodon melanotheron).

Reproduction involves multiple complex behaviours, and the effects of familiarity on such social interactions are seldom described in fish. This is particularly true for sound production and communication within aggressive or non-aggressive context. This study explores the effects of a common garden rearing without parental care of two closely related cichlid species (Nile tilapia Oreochromis niloticus and black-chinned tilapia Sarotherodon melanotheron) on their sound production features and social interactions. After 9 months in common garden rearing, from embryonic stage to first maturity, sound production and associated behaviours were recorded on specimens of the two species in intraspecific and interspecific pairings. The authors found that fish were able to produce the same kind of sounds as those recorded in similar context for their parents. Drum sounds were associated to chasing, lateral attack and courtship in O. niloticus and only to fleeing or avoidance in S. melanotheron. Specific grunts were produced in chasing, after biting and in nest building by O. niloticus, and specific rolling sounds were associated to courtship in S. melanotheron. Sound production and behaviours were not correlated to sex steroid levels, but the number of sounds recorded in aggressive context was correlated to dominance in O. niloticus. The authors conclude that one generation of common garden rearing does not modify sound features, which remain specific and innate in the two cichlids. Despite the familiarity, O. niloticus remained dominant on S. melanotheron, but the aggressiveness between the two species decreased.

Characteristics of Neurokinin-3 Receptor and Its Binding Sites by Mutational Analysis.

NKB (Neurokinin B) is already known to play a crucial role in fish reproduction, but little is known about the structure and function of NKB receptors. Based on an in silico model of the tilapia NKB receptor Tachykinin 3 receptor a (tiTac3Ra) found in the current study, we determined the key residues involved in binding to tilapia NKB and its functional homologue NKF (Neurokinin F). Despite studies in humans suggesting the crucial role of F2516.44 and M2897.43 in NKB binding, no direct peptide interaction was observed in tilapia homologs. In-silico, Ala mutations on residues F2516.44 and M2897.43 did not influence binding affinity, but significantly affected the stability of tiTac3Ra. Moreover, in vitro studies indicated them to be critical to tiNKB/tiNKF-induced receptor activity. The binding of NKB antagonists to tiTac3Ra both in-vitro and in vivo inhibits FSH (follicle stimulating hormone) and LH (luteinizing hormone) release and sperm production in mature tilapia males. Non-peptide NKB antagonist SB-222200 had a strong inhibitory effect on the Tac3Ra activation. SB-222200 also decreased LH plasma levels; two hours post intraperitoneal injection, changed sperm volume and the ratios of the different stages along the spermatogenesis in tilapia testes.

Utility of DNA barcoding in native Oreochromis species.

The importance of Oreochromis in worldwide aquaculture and regional fisheries motivates the study of their genetic diversity in their native range. In this article, all mitochondrial cytochrome c oxidase subunit I gene (COI) sequences of Oreochromis species are retrieved from Barcode of Life Data system to quantify the available DNA barcoding information from wild individuals collected within the native ranges of the respective species. It is found that 70% of the known species in the genus still lack a COI barcode, and only 15% of the available sequences are from within the respective native ranges. Many of the available sequences have been produced from specimens acquired from aquaculture and introduced, naturalized populations, making the assessment of variation within the original native range challenging. Analyses of the wild-collected fraction of available sequences indicated the presence of cryptic lineages within Nile tilapia Oreochromis niloticus and O. schwebischi, the occurrence of potential introgressive hybridization between O. niloticus and blue tilapia O. aureus, and potential ancestral polymorphism between Karonga tilapia O. karongae and black tilapia O. placidus. This article also reports a case of misidentification of O. mweruensis as longfin tilapia O. macrochir. These results stress the importance of improving the knowledge of genetic variation within the native ranges of Oreochromis species for better-informed conservation of these natural resources.

Dataset on the production of predominantly male tilapia progeny using two malawian tilapias, Oreochromis karongae and Oreochromis shiranus.

A dataset is presented of an experiment that was conducted to compare the proportions of males obtained from hormonal sex reversed pure strain of Oreochromis shiranus and from interspecific hybridization of O.karongae male x O. shiranus female. Part of the data in the dataset were published in a journal article https://doi.org/10.1016/j.aqrep.2020.100274. The data were generated from four SETs of treatments of an experiment that was conducted at the National Aquaculture Center, in Malawi. The first SET of treatment comprised hybrids from interspecific crossing of O.karongae male and O. shiranus female in a pond based breeding hapa 1. SETs 2 and 4 were for fry from hapa spawned pure cross of O.shiranus males and females in a pond based breeding hapa 2. SET 3 comprised fry from pure cross of O. shiranus males and females under controlled temperature (27°C) in an indoor re-circulatory hatchery (Tables 1 to 4). During the first part of the experiment, the fry was raised for 28 days in tanks at three replicates and was fed a fry formulated feed containing 38% crude protein, three times a day. However, for SETs 2 and 3, the feed contained 17α-methyl testosterone at 60mg/kg of feed. The second part of the experiment involved growth performance testing of fry in each SET. The growth experiment was conducted in rearing hapas that were inserted in a common pond for a period of 70 days. The body weight data were collected every 14 days (Tables 1 to 4). On the 70th day, the proportions of males and females in the four SETs was determined using Aceto-carmine staining method (Table 5). The pictures of the stained male and female gonads under compound microscope are presented in the published journal article at https://doi.org/10.1016/j.aqrep.2020.100274. Dataset presented in this paper is for body weights of fish from day 0 to day 70 and proportion of males and females in each SET on the 70th day of the experiment (Tables 1, 2, 3, 4 and 5). The data were analyzed using SPSS version 20.0. Chi-square goodness of fit test was used to investigate if the observed sex ratios significantly deviated from the expected sex ratios at 5% level of significance. The differences among fish body weights were determined using Analysis of Variance and significantly different means were separated using Duncan's multiple range test at the 5% test level of significance. These data are useful for various stakeholders that are interested in sexing juvenile tilapia and for scientists that conduct tilapia sex reversal experiments. This data can also guide hatchery managers during commercial production of all male tilapias which grow faster than those in the mixed sex tilapia culture.

Detecção de Aeromonas spp. e do gene de virulência aerolisina em tilápias do Nilo (Oreochromis niloticus) com a técnica de mPCR / Detection of Aeromonas spp. and virulence gene aerolysin in Nile tilapia (Oreochromis niloticus) using PCR technique

As infecções causadas por bactérias do gênero Aeromonas estão entre as doenças mais comuns em peixes cultivados em todo o mundo, com ocorrência de aeromoniose em todos os países que possuem cultivo de tilápia do Nilo (Oreochromis niloticus). O presente trabalho descreve o desenvolvimento de uma nova multiplex PCR (mPCR) para diagnóstico de Aeromonas spp. e identificação do gene aerolisina (aerA). Para padronização da mPCR foram utilizadas cepas de referência de várias espécies do gênero Aeromonas e de outros gêneros. Também foram usadas cepas de campo de A. hydrophila oriundas de cultivos de peixes pacamãs (Lophiosilurus alexandri) e Aeromonas spp. de tilápias do Nilo. Os primers foram desenhados com base na região 16S rRNA e aerA. Para verificar a melhor temperatura de anelamento foram utilizados gradientes entre 59°C a 61°C com 40ng de DNA molde. Os produtos da amplificação da região 16S rRNA e do gene aerA apresentaram 786 e 550pb, respectivamente. A mPCR apresentou melhor temperatura de anelamento a 57,6°C com limite de detecção das concentrações de DNA em ambos genes (16S rRNA and aerA) de 10-10g/μL. A mPCR padronizada é rápida, sensível e específica no diagnóstico de Aeromonas spp. e identificação do gene aerolisina. Esta metodologia apresenta vantagens quando comparada aos métodos de diagnóstico convencionais, podendo ser utilizada em cultivos comerciais de tilápias do Nilo ou outros peixes. A identificação do gene aerolisina é uma importante ferramenta na determinação do potencial patogênico dos isolados de Aeromonas spp. estudados.(AU)

Infections caused by bacteria of the genus Aeromonas are among the most common diseases in fish farming systems worldwide, and this disease occurs in all countries which have Nile tilapia (Oreochromis niloticus) farmed. The present work describes the development of a new multiplex PCR (mPCR) technique that diagnosis the genus Aeromonas and detects aerolysin gene (aerA). Reference strains of several Aeromonas species and other genera were used for standardization of mPCR. Strains of A. hydrophila from "pacaman" fish (Lophiosilurus alexandri) and Aeromonas spp. from Nile tilapia from farming systems were used too. Primers were designed based on the 16S rRNA region and aerA (aerolysin toxin). To verify a better annealing temperature were used gradients between 59°C and 61°C with 40ng of the DNA template. The 16S rRNA gene and the aerA gene amplification products showed 786 and 550 bp, respectively. The mPCR showed better annealing temperature at 57.6°C, and the detection limit for both genes (16S rRNA and aerA) was 10-10g/μL of the DNA. The standardized mPCR is quick, sensitive, and specific for Aeromonas spp. diagnosis and to detect aerolysin gene. This method showed advantages when compared to the conventional diagnostic methods and can be used in Nile tilapia or other fish farming systems. The detection of aerolysin gene is an important tool to determine the potential pathogenicity of Aeromonas spp. isolates.(AU)

Esteatose hepática altera acúmulo celular em tilápias do Nilo durante aerocistite infecciosa / Hepatic steatosis alters cellular recruitment during induced aerocystitis in Nile tilapia

O presente estudo avaliou a hepatotoxicidade induzida pelo CCl4 durante o efeito glicocorticoide da dexametasona (DEX) na fisiopatologia da reação inflamatória aguda em tilápias do Nilo, Oreochromis niloticus, correlacionando a funcionalidade hepática à cinética de acúmulo celular em aerocistite infecciosa. Para tal, utilizou-se 84 tilápias do Nilo distribuídas em 4 tratamentos: controle, CCl4, DEX e CCl4+DEX. Sendo amostrados 7 animais por tratamento em três períodos, isto é: seis, 24 e 48h após indução de inflamação. Utilizou-se CCl4 em dose única de 0,5mL/kg, via intraperitoneal para causar o transtorno hepático. Para indução da aerocistite utilizou-se inóculo de Aeromonas hydrophila. A dexametasona foi administrada via intramuscular na dose de 2 mg/kg de peso vivo. Os resultados revelaram que quanto maior foi à atividade sérica de aspartato aminotransferase (AST) maior foi a alteração somática do fígado, sendo estes achados inversamente proporcionais ao acúmulo celular no foco inflamatório, demonstrando menor número de células inflamatórias nos animais acometidos com maior grau de distúrbios hepáticos induzidos pelo CCl4. O estudo histopatológico revelou alterações degenerativas transitórias na fase mais aguda, pois os fígados das tilápias revelaram o acúmulo lipídeos nos hepatócitos 6h após administração de CCl4, sendo esta degeneração gordurosa não mais observada nos tempos de 24 e 48h. Contudo, a administração de CCl4 em tilápias do Nilo resultou em degeneração hepática aguda e transitória, caracterizada pelo acúmulo de gordura nos hepatócitos, aumento de AST no sangue e hepatomegalia. Com a disfunção hepática houve comprometimento do recrutamento celular em aerocistite infecciosa, indicando que há participação do fígado na resposta imune inata em peixes.(AU)

The study evaluated the hepatotoxicity induced by CCl4 during the glucocorticoid effect of dexamethasone (DEX) on the pathophysiology of the acute inflammatory reaction in Nile tilapia, Oreochromis niloticus, correlating hepatic functionality with cellular accumulation kinetics in infectious aerocystitis. Eighty- four Nile tilapia were distributed into four treatments: control, CCl4, DEX and CCl4 + DEX. Seven tilapia were sampled per treatment in three periods: 6, 24 and 48h after induction of inflammation. CCl4 was used in a single dose of 0.5mL/kg intraperitoneally to cause hepatic disorder. Aeromonas hydrophila inoculum was used to induce aerocystitis. Dexamethasone was administered intramuscularly at the dose of 2mg/kg b. w. The results revealed a higher serum aspartate transaminase (AST) activity associated with greater somatic liver alteration, being these findings inversely proportional to the cellular accumulation in the inflammatory focus, demonstrating a lower number of inflammatory cells in the animals affected with a higher degree of hepatic disorders induced by CCl4. The histopathological study revealed transient degenerative changes in the most acute phase, as livers of tilapia showed accumulation of lipids in hepatocytes 6 hours after administration of CCl4, and this fatty degeneration was no longer observed in 24 and 48h. However, administration of CCl4 in Nile tilapia resulted in acute and transient liver degeneration, characterized by accumulation of fat in hepatocytes, increased AST in the blood and hepatomegaly. With liver dysfunction there was compromise of cellular recruitment in infectious aerocystitis, indicating that there is liver involvement in the innate immune response in tilapia.(AU)

Gross pathology, physiological and toxicological responses in relation to metals and persistent organic pollutants (POPs) burden in tilapia species from Ogun River, Nigeria.

We have investigated gross pathology, physiological (steroid precursors) and toxicological responses (oxidative stress and phase II biotransformation) in relation to tissue contaminant burden in Tilapia species along the entire length (320 km) of Ogun River, Nigeria. The Ogun River is the longest and largest river in Southwestern Nigeria located along heavily industrialized cities and receives complex mixtures of effluents. A total of 1074 tilapias were collected from three sampling points (Abeokuta, Isheri and Ikorodu) and from an upstream control point (Igboho) and evaluated for gross pathological changes, hepatic transcript levels for oxidative stress and phase II biotransformation responses. Trace metal concentrations and POPs in muscle samples were analyzed using ICP-MS and GC-MS respectively. Evaluation of gross pathological changes showed a 50-, 33-, 17 and 0% prevalence of hepatic tumors at the Ikorodu, Abeokuta, Isheri and Igboho sites, respectively. Plasma concentrations of cholesterol and pregnenolone showed apparent significant decreases at downstream sites of the control point in both male and female fish (except for pregnenolone levels of male fish at Ikorodu). Inversely, gst, ugt-1, ZuCu-sod and sod significantly increased in fish collected from downstream sites, compared with the control site and these increases paralleled the significant increase in trace metal and POPs concentrations at these sites. PCA revealed a site related association between measured toxicological responses and contaminant burden, indicating a potential cause-and-effect relationship. Thus, the possible adaptation of Ogun River Tilapia species to contaminants may have significant consequences on cellular, physiological and biochemical processes regulating metabolism, growth, development and reproduction, and also have serious human health consequences, since the Ogun River is used for fisheries and domestic water supply for surrounding neighborhoods.

Peroxisome proliferator-activated receptors and biotransformation responses in relation to condition factor and contaminant burden in tilapia species from Ogun River, Nigeria.

A major development in fishery science has been the Fulton's condition factor (CF) as a reliable physiological index of fish growth and health status (Fulton 1902). As a general rule, CF-value greater than 1 (>1) should be regarded as an indicator for good growth and health. Therefore, exposure of fish to contaminants in the environment will be expected to produce a reduction in scope for growth, since energy for growth will be allocated to overcome stressful conditions. In the present study, we hypothesized that tilapia species from Ogun River (Nigeria) are experiencing severe contaminant-induced obesogen effects leading to high CF (≥ 2) in fish with pathological alterations. The environmental obesogen hypothesis has related the interaction between environmental pollutants and PPAR isoform activation In this respect, peroxisome proliferator-activated receptors (PPARs) and biotransformation responses in relation to contaminant burden were investigated in a total of 1074 specimens of Tilapias species (Tilapia guineensis, Sarotherodon galileaus and Oreochromis niloticus) collected from three areas with different degrees of anthropogenic contamination and from a putative control site along the Ogun River. Liver mRNA expression of cytochrome cyp1 isoforms (cyp1a, 1b and 1c) and PPAR isoforms (ppar-α, ß and γ) were analyzed using validated real-time PCR. Fish were also analyzed for CF and muscle contaminant burden (aliphatic and polycyclic aromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls). A significant increase in mRNA expression of cyp1- and ppar isoforms was observed in fish from polluted areas, and these results paralleled data on PCBs and PAHs tissue concentrations. Further, cyp1 isoforms showed clear sex-related differences, with higher mRNA expression in male fish than in females. Principal component analysis revealed a relationship between cyp1 isoforms, ppar-α, ß, PCBs and PAHs and these interactions may suggest a crosstalk between AhR- and PPARs mediated pathways on metabolic and energetic processes. The PCA biplot also highlighted a positive relationship between ppar-γ, body weight, total length and PAHs. The CF for fish from all the sites was ≥ 2 indicating that this parameter may not be a reliable index for evaluating fish growth and health condition, especially in wild fish population exposed to complex cocktails of environmental pollutants.

Metabolome strategy against Edwardsiella tarda infection through glucose-enhanced metabolic modulation in tilapias.

Edwardsiella tarda causes fish disease and great economic loss. However, metabolic strategy against the pathogen remains unexplored. In the present study, GC-MS based metabolomics was used to investigate the metabolic profile from tilapias infected by sublethal dose of E. tarda. The metabolic differences between the dying group and survival group allow the identification of key pathways and crucial metabolites during infections. More importantly, those metabolites may modulate the survival-related metabolome to enhance the anti-infective ability. Our data showed that tilapias generated two different strategies, survival-metabolome and death-metabolome, to encounter EIB202 infection, leading to differential outputs of the survival and dying. Glucose was the most crucial biomarker, which was upregulated and downregulated in the survival and dying groups, respectively. Exogenous glucose by injection or oral administration enhanced hosts' ability against EIB202 infection and increased the chances of survival. These findings highlight that host mounts the metabolic strategy to cope with bacterial infection, from which crucial biomarkers may be identified to enhance the metabolic strategy.

Institutional development of freshwater fish stocking in Mexico.

By using freshwater fish stocking information from the Mexican government, this work described the current situation of the national stocking and its associated fishery policy. There is a lack of effective freshwater stocking programmes as a result of limited fisheries management, unharmonized fisheries regulations and institutional performance. The fry production has decreased from 140 to 20 million in the past 11 years.

Efeitos benéficos de probióticos no intestino de juvenis de Tilápia-do-Nilo / Beneficial effects of probiotics on the intestine of juvenile Nile tilapia

Os objetivos deste trabalho foram os de avaliar o percentual de sobrevivência, a microbiota instestinal, a integridade da mucosa, e a qualidade da carcaça de juvenis de Tilápias-do-Nilo, Oreochromis niloticus, após 80 dias de alimentação com dieta contendo aditivo probiótico (Bacillus cereus 4,0x10(8) UFCg-1 e Bacillus subtilis 4,0x10(8) UFCg-1), na proporção de 4g/kg de ração peletizada. O delineamento experimental foi inteiramente casualizado com dois tratamentos, sendo um grupo controle e outro alimentado com dieta adicionada de probiótico. Foram realizados os cálculos do percentual de sobrevivência relativa, análise da microbiota intestinal por cultura microbiológica, análise histomorfométrica da mucosa intestinal e análise químico-bromatológica da carcaça dos peixes. Os resultados demonstraram que as tilápias do grupo tratado apresentaram percentual de sobrevivência relativa maior (P<0,05) que o do grupo controle e colonização intestinal por B. cereus e B. subtilis com maior (P<0,05) número de unidades formadoras de colônia em relação ao grupo controle. A análise histomorfométrica demonstrou que o grupo alimentado com aditivo probiótico apresentou vilosidades mais altas e mais largas, além de maior número de células caliciformes que o observado no grupo controle (P<0,05). Em relação à qualidade de carcaça os resultados demonstraram que houve interferência positiva (P<0,05) do probiótico no grupo tratado em relação ao controle quanto aos teores de proteína e extrato etéreo. Estes resultados permitem inferir que a suplementação com probiótico, como testado neste estudo, induziu a colonização intestinal por bactérias benéficas e promoveu maior percentual de sobrevivência relativa, diminuiu a descamação da mucosa, e favoreceu o aumento do número de células caliciformes.

The aim of this study was to evaluate the survival rate, the intestinal microbiota, the mucosal integrity, and the carcass quality of juvenile Nile Tilapia, Oreochromis niloticus, after 80 days being fed on a diet containing probiotic additive (Bacillus cereus 4.0x10(8) CFUg-1 and Bacillus subtilis 4.0x10(8) CFUg-1), at the ratio of 4g/kg of pelleted feed. The completely randomized design with two treatments was used: one control group and one group fed on the mentioned diet. The evaluation of survival rate, the intestinal microbiota analysis by microbiological culture, histomorphometrical analysis of intestinal mucosa and chemical analysis of carcass was performed. The results showed that tilapias from the treated group had higher relative survival rate (P<0.05) than the control group, higher number of colony-forming units (P<0.05) regarding intestinal colonization by B. cereus and B. subtilis, and higher rates of intestinal mucosal integrity (P<0.05), evaluated by histomorphometry. As for the latter, the group being fed on feed with probiotic additive was observed to have higher and larger villi, besides having a higher number of goblet cells than the control group. Concerning the carcass quality, the results showed that there was positive interference (P<0.05) of the probiotic on the treated group in comparison to the control group as in regard to levels of protein and ether extract. These results allow the inference that the supplementation with probiotic, as tested in this experiment, led to the intestinal colonization by beneficial bacteria and resulted in higher relative survival rate, decreased the mucosal desquamation and helped in the increase of the number of goblet cells.

Los cíclidos (pisces: cichlidae) en Colombia: introducciones, trasplantes y repoblaciones / Cichlis (pisces:: cichlidae) in Colombia: introductions, transplants and restock

Se incluye el estado actual de las especies de la familia Cichlidae introducidas a Colombia, con especial énfasis en las tilapias, analizando la situación de su distribución, el manejo, los impactos y la situación de estas actividades ilícitas. El número de introducciones alcanza la cifra de 26, entre las cuales 12 han sido registradas en hábitats dulceacuícolas y estuarinos. Existe entre estos últimos varios casos de hibridación y trasplantes a diferentes cuencas hidrográficas. Su presencia en las granjas de producción acuícola y desde hace algunos años en las pesquerías, agrava aún más el futuro de las especies nativas.

This paper includes the current status of the Cichlidae family species introduced in Colombia, with special emphasis on tilapia,. analyzing the situation of its distribution, management, and the impact and status of these illegal activities. The number of intriductions is up to 26 species, among which 12 have been found in freshwater and estuarine habitats. There are several hybridization and transplant cases to different hydrographic basins. Their presence in the aquaculture production farms and,in the fishing industry in recent years, worsens even more the future of native species.

Avaliação físico-química, microbiológica e sensorial de tilápias do nilo (Oreochromis niloticus) inteiras evisceradas submetidas a salga e secagem natural / Evaluación físico-química, microbiológica y sensorial de tilapias del nilo (Oreochromis niloticus) enteras evisceradas sometidas a sal y secado natural / Physicochemical, microbiological and sensorial evaluation of clean whole Nile tilapias (Oreochromis niloticus) submitted to salting and natural drying

Os peixes são produtos de grande valor nutritivo, além de ser uma atividade econômica, para produção de alimentos que mais cresce no mundo.Assim,o presente trabalho teve como objetivo avaliar físico quimicamente, microbiologicamente e sensorialmente amostras de tilápias após a salga e secagem natural seguidas de armazenamento à temperatura ambiente por 30 dias. Os resultados indicam que o processo de salga e secagem foi efetivo, resultando na diminuição da umidade e na penetração do sal para o interior do pescado. Microbiologicamente o produto obtido foi estável e obedecia aos padrões da ANVISA. Os provadores não foram capazes de identificar a amostra contendo o produto, quando comparadas com formulação contendo bacalhau comercial e batatas, sendo ainda que sensorialmente o produto obteve uma boa aceitação para os atributos de textura, cor, aroma e sabor.

Fishes are products of great nutritional value and an economical activity for production of the fastest growing food in the world. This work had as objective evaluates physical-chemically, microbiologically and sensorially tilapias samples after salting and natural drying following by storage to room temperature for 30 days. The results indicate that the process of salting and drying was effective, resulting in the decrease of the water contents and in the penetration of the salt for the interior of the fish, microbiologically the obtained product was stable and it obeyed the patterns of ANVISA. The painelists were not capable to identify the sample containing the product when compared with formulation containing commercial cod and potatoes, being although sensorially the product obtained a good acceptance for the texture, color, aroma and flavor atributes.

Los peces son productos de gran valor nutritivo, además de ser una actividad económica para producción de alimentos que más crece en el mundo. Así, esta investigación tuvo el objetivo de evaluar físico, químicamente, microbiológicamente y sensorialmente muestras de tilapias después de saladas y secados natural, seguidas de almacenaje a temperatura ambiente por 30 días. Los resultados indican que el proceso de salado y secado fue efectivo, resultando en la disminución de la humedad y en la penetración del sal para el interior del pescado. Microbiológicamente el producto obtenido fue estable y obedecía las normas de la ANVISA. Los probadores no fueron capaces de identificar la muestra conteniendo el producto, cuando comparadas con formulación conteniendo bacalao comercial y patatas, siendo que sensorialmente el producto obtuvo buena aceptación para los atributos de textura, color, aroma y sabor.

Análise da carga contaminante de agrotóxicos e bactérias em peixes da represa de Furnas / Analysis of the contaminant load of agrotoxic and bacteria in fish from the Furnas reservoir

O modelo agrícola brasileiro permite o uso intensivo de agrotóxicos, com possível contaminação dos corpos hídricos e a consequente bioacumulação de resíduos em peixes, cuja microbiota é influenciada pelo ambiente. Devido à sua importância na alimentação se objetivou avaliar a presença de agrotóxicos e a carga microbiana em peixes que vivem na represa de Furnas, em Minas Gerais. Realizaram-se análises das concentrações de agrotóxicos e dos micro-organismos encontrados em tilápias coletadas em vários municípios (Alfenas, Areado, Fama e Alterosa). A análise microbiológica revelou presença de mesófilos numa variação de 1,45 x 102 a 1,2 x 108 UFC/g coliformes a 35°C, de < 3 a 1,3 x 103 NMP e Salmonella sp. apenas no município de Alterosa. Segundo o Programa de Controle de Resíduos em Pescado (PCRP/2008), a Portaria n° 518/ MS de 2004 e a Legislação da Comunidade Europeia, verificou-se presença dos seguintes agrotóxicos acima dos limites máximos de resíduos (LMRs) permitidos nas amostras de peixes: Delta-BHC (0,38 mg/kg) e Endossulfan (3,18 mg/kg), na cidade de Areado Lindano e b-BHC (em concentrações diferentes: 1,20 mg/kg num ponto e 0,84 mg/kg em outro) Heptacloro (0,24 mg/kg) Heptacloro epóxi e Aldrin (em diversas concentrações, em pontos diferentes: 2,14 mg/kg, 1,34 mg/kg e 2,47 mg/kg), e Endossulfan (0,6 mg/kg) na cidade de Alfenas Lindano e b-BHC (0,87 mg/kg) e Delta-BHC (0,06 mg/kg), na cidade de Fama. Estes resultados indicam contaminação nestas áreas acima dos LMRs permitidos pela legislação brasileira e europeia.

Alterações do epitélio branquial e das lamelas de tilápias (Oreochromis niloticus) causadas por mudanças do ambiente aquático em tanques de cultivo intensivo / The influence of the aquatic environment in tanks sequetially interconnected with PVC pipes on the gill epithelium and lamellas of tilapia (Oreochromis niloticus)

Objetivou-se analisar o comportamento do epitélio branquial de tilápias, cultivadas em tanques posicionados em diferentes altitudes e interconectados por tubos de PVC. Filamentos branquiais de quatro espécimes de quatro tanques (T1, T2, T3 e T4) interconectados seqüencialmente foram submetidos à rotina histológica, para obtenção de cortes de 5µm de espessura, os quais foram corados com Hematoxilina-Eosina, ou submetidos à técnica histoquímica para glicoconjugados: PAS + solução de diástase ou Alcian Blue pH 2,5 ou Alcian Blue pH 1,0. Considerando as regiões basal, intermediária e apical dos filamentos, mensurou-se a área lamelar e contou-se o número de células mucosas em cada uma dessas regiões, o que correspondia a 0,56 mm². Verificou-se que a concentração de oxigênio, pH e a temperatura se reduziam progressivamente com a passagem da água de um tanque para outro. Em função disso, constatou-se um aumento abrupto do número de células mucosas e da área lamelar no T2, e uma redução progressiva destas medidas nos tanques que recebiam água do T2. Além disso, observou-se nos animais do T2, T3 e T4, descolamento do epitélio branquial, hiperplasia celular no espaço interlamelar e telangectasias. Conclui-se que o ambiente aquático de tanques interconectados seqüencialmente por tubos de PVC se altera ao passar de um tanque para o outro, e que estas flutuações físico-químicas se refletem no comportamento do epitélio branquial através de variações da área lamelar e do número de células mucosas.

The behavior of the gill epithelium of tilapias cultured in tanks at different altitudes and interconnected with PVC pipes was analyzed. Gill filaments of four specimens from four tanks (T1, T2, T3 e T4) sequentially interconnected were submitted to histological routine to obtain 5-mm-thick cuts that were stained with HE or submitted to histochemistry reactions PAS + diastase solution or Alcian Blue pH 2.5 or Alcian Blue pH 1.0. Considering the intermediary, apical and basal regions of the filaments, the lamellar area was measured and the amount of mucous cells was counted. It was verified that oxygen, pH, and temperature decreased progressively as the water flew from one tank to another. Thus, an increase was realized of the amount of mucous cells and the lamellar area in T2, as well as a progressive decrease of these measures on the tanks which received water from T2. Moreover, detachment of the gill epithelium, cellular hyperplasia in the interlamellar space, and telangectasias were observed in the fishes from T2, T3 e T4. It was concluded that the aquatic environment in tanks sequentially interconnected with PVC pipes suffers alterations from one tank to another, as that physico-chemical fluctuations reflect on the behavior of the gill epithelium through variations of the lamellar area and the amount of mucous cells.

Composição química e digestibilidade aparente da energia e nutrientes da farinha de resíduos da indústria de filetagem de tilápias, para a tilápia do Nilo (Oreochromis niloticus) / Apparent energy digestibility and meal nutrients from tilapia filleting industrial waste for the Nile tilapia (Oreochromis niloticus L. )

O trabalho foi realizado com objetivo de determinar os coeficientes de digestibilidade aparente (CD) da matéria seca (MS), proteína bruta (PB), energia bruta (EB) e a disponibilidade dos aminoácidos (AA), fósforo (P) e cálcio (Ca) da farinha de resíduos da indústria de filetagem de tilápias (FT) para a tilápia do Nilo. Foram utilizadas 60 tilápias com peso e comprimento médio de 80,69±15,97g e 15,97±1,87cm, respectivamente. Os animais foram submetidos à metodologia de coleta de fezes por sedimentação em tanques afunilados. A MS, PB e EB da FT apresentaram CD de 83,55, 88,13 e 84,74%, respectivamente. Apresentando valores de proteína e energia digestíveis de 44,39% e 3799,02Kcal de ED kg-1. A FT apresenta CDa médio dos AA de 91,60% com CDas variando de 67,90% para a Fen até 100% para a Arg e a Cis. O CD do P foi de 70,44 por cento apresentando 1,94% de P disponível, o CDa do Ca da FT é de 51,10%apresentando 4,02% de Ca disponível. A FT é um alimento protéico com bons índices de disponibilidade aparente de seus nutrientes e pode ser utilizado na alimentação de tilápias com a aplicação destes índices visando formular rações de custo mínimo que atendam às exigências da espécie.

Coefficients of apparent digestibility (CD) of dry matter (DM), crude protein (CP), crude energy (CE) and the availability of amino-acids (AA), phosphorus (P) and calcium (Ca) of meals from tilapia filleting industrial waste (FT) for the Nile tilapia were determined. Sixty tilapias, mean weight and length 80.69±15.97g and 15.97±1.87cm respectively, underwent feces collection by sedimentation in cone-bottom tanks. DM, CP and BE of FT had a CD of 83.55; 88.13 and 84.74% respectively, with digestible protein and energy rates equivalent to 44.39% and 3799.02 Kcal of ED kg-1. FT had average CD of AA of 91.60%, with CD varying from 67.90% for Fen up to 100% for Arg and Cis. Whereas CD of P was 70.44% with 1.94% of available P, CD of Ca of FT amounts to 51.10 percent with 4.02% of Ca available. FT is a protein feed with a good index of apparent availability of its nutrients and may be used in feed of tilapia. Above indexes will produce low cost feeds that also meet the requirements of the fish.

Detección de plesiomonas shigelloides mediante la pcr en tilapias silvestres (oreochromis mossambicus) y cultivadas (tetrahíbrido o. Mossambicus × o. Urolepis hornorum × o. Niloticus × o. Aureus) en venezuela / Detection of plesiomonas shigelloides by pcr in feral (oreochromis mossambicus) and cultured tilapias (tetrahybrid of o. Mossambicus × o. Urolepis hornorum × o. Niloticus × o. Aureus) in venezuela

Plesiomonas shigelloides es un bacilo Gram negativo, anaerobio facultativo, móvil, que pertenece a la familia Enterobactereaceae. No forma parte de la flora normal del humano, mientras que los peces dulceacuícolas como las tilapias se tienen como su reservorio primario. Considerando: a) La implicación cada vez más frecuente de este microorganismo como agente causal de enfermedades intra y extra intestinales, b) El incremento de la comercialización de tilapias silvestres y de cultivo a nivel nacional y c) La necesidad de métodos de detección e identificación rápidos y efectivos de patógenos, se aplicó el método biomolecular de la Reacción en Cadena de la Polimerasa (PCR). Se procesaron mediante la PCR, cepas de P. shigelloides y homogeneizados de pools de bazo, riñón y cerebro, y de intestino de tilapias, utilizándose oligonucleótidos iniciadores específicos para el gen 23S ARNr de P. shigelloides. Se obtuvo el reconocimiento del 75% de las 20 cepas identificadas por pruebas fenotípicas convencionales, detectándose además en 27% de los homogeneizados frescos y en 18% de los congelados. Estos resultados confirman la especificidad del método para la identificación de diversas bacterias potencialmente patógenas, su utilidad en el mejoramiento del sistema de control de calidad de granjas dulceacuícolas y en el estudio de casos clínicos, aumentando la efectividad del sistema de salud relacionado con estas áreas.

Plesiomonas shigelloides is a Gram negative rod, facultative anaerobic, motile, that belongs to the Enterobacteriaceae. It’s not part of the normal human flora, while fresh water fish like tilapias are thought to be its primary reservoir. Considering: a) The more frequent implication of this microorganism as the causal agent of intra and extraintestinal infections, b) The wide spread of national commercialization of feral and cultured tilapias and c) The need for rapid and effective detection and identification methods, the biomolecular technique of Polymerase Chain Reaction (PCR) was applied. Strains of P. shigelloides and pools of homogenates from spleen, kidney and brain and the intestine of tilapias were processed by PCR, using specific primers for the gene 23S rRNA of P. shigelloides. The 20 strains identified by conventional phenotypic traits were identified in 75%, additionally it was detected in 27% of the fresh homogenates and in 18% of the frozen ones. These results confirm the specificity of the technique for the identification of a diverse range of potential pathogenic bacteria, its usefulness in the improvement of quality control in freshwater farms and in the study of clinical cases, improving the effectiveness of health systems related with these areas.

Aplicação de métodos diretos e indiretos para produção de populações monossexuais na tilapicultura / Direct and indirect methods applied to the production of monosexual populations in tilapia breeding programs

No cultivo de tilápias, as espécies ao gênero Oreochromis apresentam maior importância devido a sua fácil adaptabilidade às condições de cultivo, rusticidade, altas taxas de crescimento e também à grande aceitação de sua carne pelo mercado consumidor. Apesar de suas vantagens, um grande problema existente com relação ao cultivo destes peixes está relacionado com sua maturidade sexual precoce e elevada prolificidade, o que pode levar à ocorrência de superpopulação em condições de cultivo. Este fato pode provocar grandes prejuízos aos cultivos devido à redução das taxas de crescimento dos animais envolvidos na reprodução, competição dos filhotes com os adultos pelo alimento e, em casos extremos, mortalidade devido à queda de qualidade da água. Tendo em vista esta problemática, diversas técnicas de produção de propulações monosexo têm sido estudadas. Dentre estas técnicas pode-se considerar aquelas que fazem o controle endógeno direto e indireto do sexo fenotípico. As técnicas de controle direto são aquelas que envolvem a masculinização, feminilização ou esterilização a partir da utilização de hormônios, antiestrógenos, inibidores enzimáticos e compostos esterilizantes. Os tratamentos indiretos utilizam manipulação ambiental, genética ou endócrina para a produção de indivíduos com gametas monosexuais. Atualmente a técnica mais difundida é o método direto, onde se utilizam tratamentos com o hormônio 17 a metiltestosterona incorporado à ração. Contudo, já existe uma tendência de utilização das técnicas indiretas e diretas que não utilizam hormônios esteróides, devido à preocupação do mercado consumidor com a utilização dos hormônios esteróides nestes cultivos.