Genetic monitoring of the Amazonian fish matrincha (Brycon cephalus) using RAPD markers: insights into supportive breeding and conservation programmes

The importance of genetic evaluations in aquaculture programmes has been increased significantly not only to improve effectiveness of hatchery production but also to maintain genetic diversity. In the present study, wild and captive populations of a commercially important neotropical freshwater fish, Brycon cephalus (Amazonian matrincha), were analyzed in order to evaluate the levels of genetic diversity in a breeding programme at a Brazilian research institute of tropical fish. Random Amplified Polymorphic DNA fingerprinting was used to access the genetic variability of a wild stock from the Amazon River and of three captive stocks that correspond to consecutive generations from the fishery culture. Although farmed stocks showed considerably lower genetic variation than the wild population, a significantly higher level of polymorphism was detected in the third hatchery generation. The results seem to reflect a common breeding practice on several hatchery fish programmes that use a small number of parents as broodstocks, obtaining reproductive success with few non-identified mating couples. The obtained data were useful for discussing suitable strategies for the genetic management and biodiversity conservation of this species.

Isolation and characterization of eight microsatellite loci in Leporinus macrocephalus (Characiformes : Anostomidae) and cross-species amplification

Leporinus macrocephalus is a species endemic to the Paraguay River basin and an important fishery resource, as well as a valuable species in aquaculture programs. A total of eight polymorphic microsatellite loci were isolated and characterized. A population survey was conducted involving 45 specimens whereby a large number of alleles (range 5-17 among loci), a highly observed (0.1667-0.6129) and an expected (0.6967-0.9448) heterozygosity was detected, indicating its usefulness in population genetics studies. Cross-species amplification was successful in eight Characiformes species.

Deep barcode divergence in Brazilian freshwater fishes: the case of the Sao Francisco River basin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetic differentiation among ten populations of the genus Neoplecostomus (Teleostei: Loricariidae) from the upper Parana River basin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetic variability of two populations of Pseudoplatystoma reticulatum from the Upper Paraguay River Basin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetic Markers in Wild Population of Curimbata (Prochilodus lineatus) from Mogi-Guacu River

Within the genus Prochilodus, the species Prochilodus lineatus is certainly the most studied one from a cytogenetic point of view. In this study, a cytogenetic characterization of specimens of P. lineatus from Mogi-Guacu River was performed in the period from 2003 to 2007, through utilization of cytogenetic markers, such as Giemsa, Ag-NOR, C-banding and cytogenetical-molecular markers (FISH) to detect both 5S and 18S ribosomal genes. All analyzed individuals presented 2n=54 meta/submetacentric chromosomes, besides bearing up to 7 supernumerary Microchromosomes. Polymorphic NORs were detected on a single chromosomal pair. The constitutive heterochromatin was distributed at centromeric region of all chromosomes in the A complement, while the microchromosomes were totally heterochromatic. A syntenic distribution of 5S and 18S ribosomal genes was detected, comprising the NOR-bearing chromosomal pair. No additional ribosomal clusters in other chromosomes were observed. Although the karyotype features are commonly conserved within the genus Prochilodus, the few differences on the distribution of both ribosomal genes and heterochromatin when compared to specimens of P lineatus from other localities can be associated to the evolutionary changes that these repetitive sequences have undergone through the years.

DNA barcodes discriminate freshwater fishes from the Paraiba do Sul River Basin, São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Occurrence of ZZ/ZW sex chromosomes in Thoracocharax stellatus fish (Characiformes, Gasteropelecidae) from the Araguaia River, south America

The karyotypic and chromosomal characteristics of the hatchetfish Thoracocharax stellatus from the Araguaia River, Brazil (Araguaia-Tocantins basin) were analyzed using Giemsa, AgNO3, and CMA(3) fluorescent staining, and C-banding. The diploid chromosome number was 54 and the karyotypes of females and males were composed of six metacentrics, six submetacentrics, six subtelocentrics and 36 acrocentrics. Two impaired acrocentric chromosomes were detected in the female karyotype. C-banding showed heterochromatic blocks at several chromosomes and an entirely heterochromatic acrocentric chromosome in females that was lacking in the male karyotype. This discovery indicated a heteromorphic sex chromosome system of the ZZ/ZW type. Ag-staining and CMA(3) fluorescence revealed one major chromosome pair bearing the NORs with the presence of additional signals in some metaphases. Both heterochromatic segments associated with Ag-NORs and the W chromosome were positively stained by CMA(3). Considering the present data and previous findings it is hypothesized that the occurrence of ZW sex chromosome system is widespread in the genus Thoracocharax.

Characterization of invasive fish species in a river transposition region: evolutionary chromosome studies in the genus Hoplias (Characiformes, Erythrinidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessment of the ichthyofauna in stretches under the influence of Salto Grande Reservoir (Middle Paranapanema River, SP/PR, Brazil).

Aim: To analyze the composition, species richness and spatial distribution of the fish fauna in the area under influence of the Salto Grande Reservoir; Methods: Fish were caught every two months from November/05 to October/06, using gill nets, seining nets and sieve; Results: It was registered 67 fish species, 1,964 individuals and 146.2 kg, representing CPUEn of 1,964 and CPUEb of 278 kg. The most representative orders were Characiformes, with 29 species, Siluriformes (21 species) and Perciformes (11 species) Nine non-native species were registered. The most abundant species in the reservoir were Astyanax altiparanae, Steindachnerina insculpta and Acestrorhynchus lacustris, indicating the predominance of medium and small fishes in this reservoir. The dendrogram of similarity separated the Dam and Pedra Branca stretches from Pardo River Mouth, indicating differences in the assemblages. The species turnover among the stretches was demonstrated by the beta diversity, which may be related to the diversity of habitat; Conclusions: Although being a small reservoir, it displays great habitat diversity, reflecting in the composition and structure of fish assemblages.

Influence of cage fish farming on the diet of dominant fish species of a Brazilian reservoir (Tiete River, High Parana River basin)

The cage farming of aquatic organisms was initiated 50 years ago, and was introduced to Brazil in the 1990's. In these systems, there is an input of organic matter from ration that is not totally used by the cage fishes, becoming available for the organisms of adjacent biota, including fish fauna. The aim of this work is to evaluate the interference in the diet of three dominant fish species (Plagioscion squamosissimus Heckel, 1840, Astyanax altiparanae Garutti and Britski, 2000 and Metynnis maculatus Kner, 1858) associated with ish cage farming. For determination of the diet, the Alimentary Index (AI) was used. In both stretches (around cage farm and control), P. squamosissimus selected aquatic insects, while A. altiparanae preferred terrestrial insects and M. maculatus eats ration remains. Diferences in abundance of these feeding resources found of the stomach content were observed among the two stretches. Thus, the small alterations in the diets of P. squamosissimus and A. altiparanae, indicate that cage farming can change the diet of resident species in reservoirs. This practice also influences the population structure of fish species, since higher middle standard lengths were found in A. altiparanae and P. squamosissimus populations resident around cage farms, in relation to the control stretch.

Supernumerary chromosome inheritance in the curimbata (Prochilodus lineatus) of the Mogi-Guacu River

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of a cage farming on the population of the fish species Apareiodon affinis (Steindachner, 1879) in the Chavantes reservoir, Paranapanema River SP/PR, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytogenetic analysis in the incertae sedis species Astyanax altiparanae Garutti and Britzki, 2000 and Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae) from the upper Parana river basin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative cytogenetics of ten species of cichlid fishes (Teleostei, Cichlidae) from the Araguaia River system, Brazil, by conventional cytogenetic methods

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)