1,024 research outputs found
Life history and production of Capitella capitata (Polychaeta: Capitellidae) in RÃo de la Plata Estuary (Argentina)
A benthic survey was carried out from November
1998 to December 1999 in the tidal flats of BahÃa
Samborombón (RÃo de la Plata estuary, Argentina),
in order to study the population structure,
reproductive aspects, growth and secondary
production of Capitella capitata (Fabricius, 1780).
Growth was analyzed using ELEFAN routine, and
the secondary production was estimated by Hynes
and Coleman's method (1968). C. capitata did not
present periods of very important recruitments
throughout the year; however, the abundance of
smallest size classes was higher during summer and
autumn. The summer cohort showed a growth rate
(K) of 2.05 and a seasonal growth oscillation (C) of
0.6, pointing out that worms grew very slowly
during winter months. The life span of this cohort
was 13 months. The autumn cohort showed a lower
growth rate (K= 1.5) and its growth was lowest
during winter. The life span was 15 months for this
cohort. C. capitata in Punta Rasa presented an
extended reproductive period, with absence of
activity during winter months. The type of eggs and
larvae suggest that C. capitata has benthic larval
development in the study area, destining its reproductive effort to the production of a low number of eggs, and assuring larvae survival through incubation in brooding tubes. The annual mean biomass in Punta Rasa was 0.117 g m-2 (AFDW), with a mean secondary production of 0.23 g m-2 y-1 and a P/B ratio of 1.96 y-1. The relatively low density, biomass production and P/B ratio of C.
capitata in Punta Rasa can be considered as reference values for this species inhabiting undisturbed or moderately disturbed areas
DNA extraction from formalin-fixed Franciscana tissues
The present paper reports the extraction of DNA from formalin-fixed Pontoporia blainvillei tissues. Following the Vachot and Monerot (1996) protocol, fragmented DNA (300-700bp) was extracted from more than 95% of liver and muscle samples. DNA yield in liver samples was significantly higher than in muscle samples (4.574 ± 1.169mg DNA/mg versus 0.808 ± 0.297mg DNA/mg). Similar results were obtained from nine other species of cetaceans and five species of pinnipeds. It is of special interest to have a method that allows the utilisation of museum specimens not originally preserved for genetic studies,
which may include rarely available, declining or extinct species.
SPANISH: El presente trabajo reporta la extracción de ADN a partir de tejidos formolizados de Pontoporia blainvillei. Siguiendo el protocolo de Vachot y Monerot (1996) se pudo extraer ADN degradado (300-700pb) en más del 95% de las muestras de hÃgado y músculo analizadas. El rendimiento en ADN fue significativamente mayor en muestras de hÃgado que en muestras de músculo (4.574 ± 1.169mg DNA/mg tejido húmedo versus 0.808 ± 0.297mg DNA/mg tejido húmedo). Resultados similares se obtuvieron en otras nueve especies de Cetáceos y cinco de PinnÃpedos. Resulta de gran interés contar con un método que permita la utilización de especÃmenes depositados en museos y que no hayan sido originalmente colectados para estudios genéticos, incluyendo especies de difÃcil obtención, en franca declinación o extintas
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