38 research outputs found
Analysis of tectonic-controlled fluvial morphology and sedimentary processes of the western Amazon Basin: an approach using satellite images and digital elevation model
Nucleocytoplasmic transport: a thermodynamic mechanism
The nuclear pore supports molecular communication between cytoplasm and
nucleus in eukaryotic cells. Selective transport of proteins is mediated by
soluble receptors, whose regulation by the small GTPase Ran leads to cargo
accumulation in, or depletion from the nucleus, i.e., nuclear import or nuclear
export. We consider the operation of this transport system by a combined
analytical and experimental approach. Provocative predictions of a simple model
were tested using cell-free nuclei reconstituted in Xenopus egg extract, a
system well suited to quantitative studies. We found that accumulation capacity
is limited, so that introduction of one import cargo leads to egress of
another. Clearly, the pore per se does not determine transport directionality.
Moreover, different cargo reach a similar ratio of nuclear to cytoplasmic
concentration in steady-state. The model shows that this ratio should in fact
be independent of the receptor-cargo affinity, though kinetics may be strongly
influenced. Numerical conservation of the system components highlights a
conflict between the observations and the popular concept of transport cycles.
We suggest that chemical partitioning provides a framework to understand the
capacity to generate concentration gradients by equilibration of the
receptor-cargo intermediary.Comment: in press at HFSP Journal, vol 3 16 text pages, 1 table, 4 figures,
plus Supplementary Material include
Characterization and genesis of waterfalls of the Presidente Figueiredo region, Northeast State of Amazonas, Brazil
Environmental changes in the western AmazĂŽnia: morphological framework, geochemistry, palynology and radiocarbon dating data
PRELIMINARY REPORT ON THE PUTATIVE ASSOCIATION OF IL10 -3575 T/A GENETIC POLYMORPHISM WITH MALARIA SYMPTOMS
Enteroparasites and commensals among children in four peripheral districts of UberlĂąndia, State of Minas Gerais
A well-kept treasure at depth: precious red coral rediscovered in Atlantic deep coral gardens (SW Portugal) after 300 years
The highly valuable red coral Corallium rubrum is listed in several Mediterranean Conventions for species protection and management since the 1980s. Yet, the lack of data about its Atlantic distribution has hindered its protection there. This culminated in the recent discovery of poaching activities harvesting tens of kg of coral per day from deep rocky reefs off SW Portugal. Red coral was irregularly exploited in Portugal between the 1200s and 1700s, until the fishery collapsed. Its occurrence has not been reported for the last 300 years.info:eu-repo/semantics/publishedVersio
Population Genetics of GYPB and Association Study between GYPB*S/s Polymorphism and Susceptibility to P. falciparum Infection in the Brazilian Amazon
Merozoites of Plasmodium falciparum invade through several pathways using different RBC receptors. Field isolates appear to use a greater variability of these receptors than laboratory isolates. Brazilian field isolates were shown to mostly utilize glycophorin A-independent invasion pathways via glycophorin B (GPB) and/or other receptors. The Brazilian population exhibits extensive polymorphism in blood group antigens, however, no studies have been done to relate the prevalence of the antigens that function as receptors for P. falciparum and the ability of the parasite to invade. Our study aimed to establish whether variation in the GYPB*S/s alleles influences susceptibility to infection with P. falciparum in the admixed population of Brazil.Two groups of Brazilian Amazonians from Porto Velho were studied: P. falciparum infected individuals (cases); and uninfected individuals who were born and/or have lived in the same endemic region for over ten years, were exposed to infection but have not had malaria over the study period (controls). The GPB Ss phenotype and GYPB*S/s alleles were determined by standard methods. Sixty two Ancestry Informative Markers were genotyped on each individual to estimate admixture and control its potential effect on the association between frequency of GYPB*S and malaria infection.GYPB*S is associated with host susceptibility to infection with P. falciparum; GYPB*S/GYPB*S and GYPB*S/GYPB*s were significantly more prevalent in the in the P. falciparum infected individuals than in the controls (69.87% vs. 49.75%; P<0.02). Moreover, population genetics tests applied on the GYPB exon sequencing data suggest that natural selection shaped the observed pattern of nucleotide diversity.Epidemiological and evolutionary approaches suggest an important role for the GPB receptor in RBC invasion by P. falciparum in Brazilian Amazons. Moreover, an increased susceptibility to infection by this parasite is associated with the GPB S+ variant in this population