14 research outputs found
Morfologia e desenvolvimento ultraestrutural do sistema renal de embriões bovinos com idade gestacional entre 10 e 50 dias
Refining the Maritime Foundations of Andean Civilization: How Plant Fiber Technology Drove Social Complexity During the Preceramic Period
Identificación de bacterias marinas cultivables de la ciudad costera Comodoro Rivadavia, Argentina
This study identifies marine bacteria obtained
from three sites along Comodoro Rivadavia coast, south of
Argentina. Seawater and intertidal sediment samples were
collected. Two of the sites were located close to the city sewage
system (CR1, CR2) and the third one (CR3) was near from an
oil buoy. Bacterial counts were performed on four culture
media: BBR, BRN, mineral medium with crude oil and gas oil
and ENDO for coliforms. The identification of bacteria was
performed by using fatty acid methyl esters. The counts resulted
positive to total coliforms and faecal coliforms in sites CR1
and CR2 and resulted negative in site CR3 except in autumn.
We isolated 469 strains, to which a fatty acid extraction and
identification were performed. The system identified 37 genera
and 54 species in only 236 strains. The other strains were
unidentified because they were not found in Sherlock data base.
Pseudoalteromonas was the genus frequently found isolated
and the enterobacteria group was conformed by Citrobacter,
Enterobacter and Escherichia. The principal components
analysis related the winter season to Gram positive strain, and
autumn season was asociated to the biggest biodiversity of
genera.Este estudio identifica bacterias marinas
obtenidas de tres sitios costeros de la ciudad de Comodoro
Rivadavia, sur de Argentina. Se tomaron muestras de agua de
mar y sedimento del intermareal. Dos de los sitios se ubicaron
cerca de desagües cloacales (CR1, CR2) y el tercero (CR3) fue
cerca de una boya de carga de hidrocarburos. Se realizaron
recuentos bacterianos en cuatro medios de cultivo: BBR, BRN,
medio mineral con petróleo gas oil y ENDO para coliformes.
Las bacterias fueron identificadas utilizando ácidos grasos metíl
esteres. Los recuentos de coliformes totales y fecales fueron
positivos en los sitios CR1 y CR2 y negativos para CR3 con
excepción de la estación de otoño. Se aislaron 469 cepas a las
que se les realizó la extracción de ácidos grasos e identificación.
El sistema identificó 37 géneros y 54 especies en solo 236 cepas.
Las restantes cepas no fueron identificadas debido a que no se
encontraron en la base de datos Sherlock. Pseudoalteromonas
fue el género que más frecuentemente se encontró aislado y el
grupo de las enterobacterias estuvo integrado por Citrobacter,
Enterobacter y Escherichia. El análisis de componentes
principales asoció el invierno a las cepas Gram positivas y el
otoño se asoció con la mayor biodiversidad de género
Identificaci\uf3n de bacterias marinas cultivables de la ciudad costera Comodoro Rivadavia, Argentina
Objectively assessed physical activity and associated factors of sedentary behavior among survivors of stroke living in Cape Town, South Africa
Five million years of Antarctic Circumpolar Current strength variability
International audienceAbstract The Antarctic Circumpolar Current (ACC) represents the world’s largest ocean-current system and affects global ocean circulation, climate and Antarctic ice-sheet stability 1–3 . Today, ACC dynamics are controlled by atmospheric forcing, oceanic density gradients and eddy activity 4 . Whereas palaeoceanographic reconstructions exhibit regional heterogeneity in ACC position and strength over Pleistocene glacial–interglacial cycles 5–8 , the long-term evolution of the ACC is poorly known. Here we document changes in ACC strength from sediment cores in the Pacific Southern Ocean. We find no linear long-term trend in ACC flow since 5.3 million years ago (Ma), in contrast to global cooling 9 and increasing global ice volume 10 . Instead, we observe a reversal on a million-year timescale, from increasing ACC strength during Pliocene global cooling to a subsequent decrease with further Early Pleistocene cooling. This shift in the ACC regime coincided with a Southern Ocean reconfiguration that altered the sensitivity of the ACC to atmospheric and oceanic forcings 11–13 . We find ACC strength changes to be closely linked to 400,000-year eccentricity cycles, probably originating from modulation of precessional changes in the South Pacific jet stream linked to tropical Pacific temperature variability 14 . A persistent link between weaker ACC flow, equatorward-shifted opal deposition and reduced atmospheric CO 2 during glacial periods first emerged during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer-than-present intervals of the Plio-Pleistocene, providing evidence of potentially increasing ACC flow with future climate warming