Caracterización genética de lotes de "Brycon orbignyanus" utilizados en programas de repoblamiento

Objetivo. Caracterizar geneticamente dos lotes y una progenie de Brycon orbignyanus destinados para programas de repoblamiento, utilizando la tecnica molecular de RAPD (Random amplified polymorphic DNA). Materiales y metodos. Se analizaron 58 reproductores originarios de dos piscicolas ubicadas en las ciudades de Castillo (A:30 individuos) y Porto Ferreira (C:28 individuos), mantenidos en cautiverio hace seis anos en la estacion de acuicultura e hidrologia de la Duke Energy Internacional (Geracao Paranapanema) (Sao Paulo-Brasil). Treinta larvas de la progenie del lote A (B) tambien se analizaron. Resultados. Los 14 primers usados produjeron 87 fragmentos de los cuales 70.11% fueron polimorficos. Fueron observadas diferencias (p.0.05) en la frecuencia de 31 fragmentos, con tres exclusivos para el lote A. Los valores de divergencia, distancia e identidad genetica mostraron que la diversidad genetica del lote A fue mantenida en la progenie y que existe una baja diferenciacion entre los lotes de reproductores. El analisis de variancia molecular mostro que la mayor parte de la variacion esta dentro de cada lote (87.45%) y no entre ellos (12.55%). Este resultado se corroboro con los valores de FST (0.125) y con el dendrograma, que indicaron una moderada diferenciacion genetica, sin la formacion de agrupamientos. Conclusiones. La diversidad genetica fue preservada en la progenie debido al manejo eficiente de la reproduccion. No hubo una diferenciacion genetica entre los lotes de reproductores, debido posiblemente a que el origen natural de ambos fue el rio Parana.Objective. To genetically characterize two Brycon orbignyanus stocks and one progeny intended for restocking programs using the molecular technique RAPD (Random Amplified Polymorphic DNA). Materials and methods. Fifty eight broodstocks native to two fish farms in the cities of Castilho (A:30 individuals) and Porto Ferreira (C:28 individuals) were analyzed. The fish had been maintained for six years in captivity in the aquaculture and hydrology station of Duke Energy International (Geracao Paranapanema. Sao Paulo - Brazil); thirty larvae of progeny from the stock A (B) were also analyzed. Results. The fourteen primers used produced 87 fragments of which 70.11% were polymorphic. Differences were observed (p.0.05) in the frequency of 31 fragments, with three exclusive from stock A. The values for divergence, distance and genetic identity showed that genetic diversity of stock A was maintained in progeny and that a low differentiation exists among reproductive stocks. Analysis of Molecular variance showed that most of the variation is inside each stock (87.45%) and not between them (12.55%). This result was corroborated with FST (0.125) values and with the dendrogram indicating a moderate genetic differentiation, without cluster formation. Conclusions. Genetic variability was maintained in progeny, possibly because both were native to the Parana rive

Larval development of hoplias cf. Lacerdae (Pisces: Erythrinidae) and delayed initial feeding effects

Larval development of Hoplias cf. lacerdae was studied under laboratory conditions. After hatching, ontogenetic changes were recorded on food-deprived larvae in 12-hour intervals. Mouth opening occurred after 2.5 days and notochord terminated flexure in 6.5 days. Notochord length increased at a constant rate until complete yolk absorption (13,5 days). Larval dry weight and body height diminished gradually up to 21 days after hatching, when all starved larvae died. Every 12 hours after yolk absorption, groups of larvae (n=15), were separeted, and fed with Artemia nauplii for 10 days. The point-of-no-return (when 50% of larvae were unable to feed or to assimilate ingested food after delayed feeding), was not apparent in this species