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O Pantanal é uma bacia sedimentar quaternária localizada na Bacia do Alto Rio Paraguai, na Região Centro-Oeste do Brasil. O trato de sistemas deposicionais é composto pela planície fluvial do rio Paraguai, que coleta as águas de vários eques aluviais, dos quais o mais notável é o megaleque do rio Taquari. No megaleque, o rio Taquari corre em dois compartimentos geomorfológicos distintos: um cinturão de meandros na porção superior do leque e um lobo distributário atual na porção média/inferior. Avulsão fluvial, um conjunto de processos que culmina com a mudança do curso de um rio, é fenômeno natural na evolução do megaleque do Taquari, mas que vem sendo acelerado nos últimos anos por atividades agropastoris desenvolvidas nas cabeceiras situadas nos planaltos a leste do Pantanal. O fenômeno de avulsão não ocorre naparte superior do megaleque do Taquari, porque o cinturão de meandros está entrincheirado sobre sedimentos de lobos maisantigos. No lobo distributário a descarga fluvial paulatinamente decresce e o rio torna-se progressivamente mais estreito emais raso, sendo as avulsões conseqüências naturais do rompimento de diques marginais. Muitas avulsões ocorreram nasúltimas décadas e casos documentados mostram que as mudanças no curso do rio podem ocorrer em poucos anos.

ABSTRACT. Previous work has suggested that seasonal and interannual upwelling of deep, cold, radiocarbon-depleted waters from the South Atlantic has caused variations in the reservoir effect (R) through time along the southern coast of Brazil. This work aims to examine the possible upwelling influence on the paleoreservoir age of Brazilian surficial coastal waters based on paired terrestrial/marine samples obtained from archaeological remains. On the Brazilian coast, there are hundreds of shell middens built up by an ancient culture that lived between 6500 to 1500 yr ago, but there are few shell middens located on open-coast sites with a known upwelling influence. Three archaeological sites located in a large headland in Arraial do Cabo and Ilha de Cabo Frio on the southeastern coast of Brazil, with open-ocean conditions and a well-known strong and large upwelling of the Malvinas/Falkland current, were chosen for this study. The 14 C age differences between carbonized seed and marine samples varied from 281 ± 44 to 1083 ± 51 14 C yr. There are also significant age differences between carbonized seed samples (977 14 C yr) and marine samples (200 and 228 14 C yr) from the same archaeological layer that cannot be explained by a reservoir effect or an old-wood effect for charcoal. Therefore, the present data from the southeastern Brazilian coast are inconclusive for identifying an upwelling effect on R. To do so, it would be necessary to more precisely define the present-pre-bomb R in upwelling regions, and to analyze paired marine/terrestrial samples that are contemporaneous beyond doubt.

Luehea candicans Mart. et Zucc. (Tiliaceae) is known as 'açoita-cavalo' and is one of the most important medicinal plants found in the Brazilian cerrado. The crude methanolic extracts of the branches and leaves and their fractions were evaluated using the following cancer cell lines: MCF-7 (breast), NCI-ADR (breast expressing the multidrug resistance phenotype), NCI-460 (lung), UACC-62 (melanoma), 786-0 (kidney), OVCAR (ovarian), PCO-3 (prostate), HT-29 (colon) and K-562 (leukaemia). The crude methanolic extracts from the branches (B) and leaves (L) were able to inhibit the growth of the K-562 and 786-0 cell lines in a dose-dependent manner, with GI(50) values of 8.1 and 5.4 µg mL(-1), respectively. The hexane (L1), chloroform (L2) and methanol (L4) fractions derived from extract L showed a high selectivity and pronounced cytostatic activity against 786-0 (GI(50) ~ 40 µg mL(-1)). A significant amount of lupeol was isolated from fraction L2. The chloroform (B2) and methanol (B3) fractions derived from extract (B) exhibited less selectivity, showing the highest cytostatic activity against K-562, NCI-ADR, OVCAR, MCF-7 and NCI-460 cells, with GI(50) values between 27 and 40 µg mL(-1). Lupeol, betulin, a mixture of steroids, (-)-epicatechin, vitexin and liriodendrin were isolated from these active fractions.

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