Interspecific fish hybrids in Brazil: management of genetic resources for sustainable use

Serrasalmid and pimelodid fish hybrids represent important advances for aquaculture in Brazil, but they also constitute serious genetic risks to cultivated and natural populations. Serrasalmid hybrids (tambacu, tambatinga and patinga) result from crosses between Colossoma macropomum, Piaractus mesopotamicus and Piaractus brachypomus. Pimelodid hybrids (ponto e virgula, cachandia and cachapira) arise from crosses between Pseudoplatystoma corruscans, Pseudoplatystoma reticulatum, Phractocephalus hemioliopterus and Leiarius marmoratus. The problems associated with hybrids mainly result from inappropriate use because these animals are reproductively compatible with their parental species. This review shows that monitoring of fish hybrids using genetic techniques is necessary for their sustainable development in aquaculture. The genetic technologies used to identify fish hybrids include cytogenetic methods, which are considered to be low cost, and polymerase chain reaction-based molecular markers, which are associated with high throughput. Therefore, both types of genetic methodologies should be applied in monitoring programs aimed at brood stock management, wild stocks, the trade of hybrid juveniles and processed fish products in markets. Moreover, physical and genetic confinement of hybrids in aquaculture operations will be necessary to avoid the problems posed by these animals. The expected result of these measures will be the production of genetically improved animals by fish farms, allowing the sector to develop further and offering high-quality animal protein.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Transmission rate variation among three B chromosome variants in the fish Prochilodus lineatus (Characiformes, Prochilodontidae)

Estudos citogenéticos foram desenvolvidos em Prochilodus lineatus (Valenciennes 1836), os quais descrevem um interessante sistema de pequenos cromossomos supranumerários. O objetivo deste trabalho foi estudar a frequência e morfologia dos cromossomos B em indivíduos a partir da linhagem parental e os padrões de herança destes elementos em indivíduos obtidos a partir de cruzamentos controlados na espécie P. lineatus. A taxa de transmissão dos cromossomos B revelaram um kB=0,388 para o tipo acrocêntrico, kB=0,507 para o tipo metacêntrico e kB=0,526 submetacêntrico. Os resultados obtidos levantam hipóteses de que os cromossomos B do tipo acrocêntrico se encontram em fase de extinção, enquanto que os supranumerários do tipo metacêntrico e submetacêntrico encontram-se em fase de neutralização, seguindo uma taxa de transmissão Mendeliana.Cytogenetic studies were developed in Prochilodus lineatus (Valenciennes 1836), describing an interesting system of small supernumerary chromosomes. The purpose of this work is to study the frequency and morphology of B chromosomes in individuals from the parental line and the inheritance patterns of these elements in individuals obtained from controlled crosses in the species P. lineatus. The transmission rate of B chromosomes revealed a kB=0.388 for the acrocentric type, a kB=0.507 for the metacentric type and a kB=0.526 for the submetacentric type. The obtained results raise hypothesis that B-acrocentric chromosomes are involved in an extinction process in this species, while the metacentric and submetacentric supernumerary elements comprises a neutral mechanism and follows a Mendelian transmission rate

Aloe vera bathing improved physical and humoral protection in breeding stock after induced spawning in matrinxa (Brycon amazonicus)

In this study, we show that induced spawning causes stress, an intense loss of epithelia and immunosuppression, decreasing physical and humoral protection in fish, effects that were prevented or improved in fish bathed with Aloe vera. A. vera has several medicinal properties, including wound healing and immunostimulatory effects, which we observed in this study. Fish bathed with A. vera had a higher number of epidermal goblet cells and, in general, an improved wound healing rate compared with the control after induced spawning. These effects might be related to (1) the stimulation of leukocyte activity, represented here by the increased leukocyte respiratory activity triggered by A. vera (leukocytes are recognized as playing an important role in wound repair); (2) the antimicrobial properties of A. vera, which decrease wound infection and accelerate the healing process; and (3) several mechanisms that explain the healing effect of A. vera (increased collagen synthesis, rate of epithelialization, and anti-inflammatory and moisturizing effects). Our results also suggest that caution is necessary during the induced spawning process, especially during stripping, and A. vera bathing is recommended after intensive aquaculture operations. (C) 2015 Elsevier Ltd. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Repetitive DNA probe linked to sex chromosomes in hybrids between Neotropical fish Leporinus macrocephalus and Leporinus elongatus (Characiformes, Anostomidae)

Interspecific hybrids of fish can offer important advances in the zootechnical exploration of this animal group. However, hybrids can pose serious biological risks to the environment and natural populations, making genetic characterization and monitoring of hybrids produced in fish culture important concerns. In the present study, individuals of the hybrid 'Piaupara' were characterized by fluorescence in situ hybridization (FISH) using sex-specific probes to differentiate the respective parental contributions from female Leporinus macrocephalus (Piaucu) and male Leporinus elongatus (Piapara). The application of this technique demonstrated a difference in hybridization patterns between males and females of L. elongatus and L. macrocephalus, mainly due to the fact that the NOR-bearing chromosomes of L. elongatus contain some homology with the probe. This allowed us to detect a clear sex-specific distinction of the hybrid 'Piaupara', demonstrating that this technique is well-suited for the characterization of these hybrids. Moreover, this technique offers an important methodological advance for the study of diverse sex chromosome systems of Leporinus, supplying valuable information about the origin and establishment of a recently described sexual system in this genus. Copyright (C) 2009 S. Karger AG, BaselFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq