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91.
An increase in bioavailable tin in the environment could result in bioaccumulation thereof in agricultural crops, and therefore, have adverse health consequences on humans that eat these crops. The aims of the current study were thus to assess the uptake of Sn by spinach plants, and the subsequent effects this will have on the uptake of Na, Zn, K, Ca, and Mg as well as the growth of spinach plants. Spinach plants were grown in sand culture and received tin at concentrations of 0.02, 0.2, 2 and 20 mg/L along with a nutrient solution. The uptake of tin at detectible concentrations only occurred at the highest concentrations (2 and 20 mg/L), and it was mostly retained in the roots of the plants. Tin additions also resulted in no visual toxicity symptoms, and might be beneficial to biomass production. Further field trials are needed to ensure that these experimental results remain true under field conditions. 相似文献
92.
93.
Mu J Joy DA Duan J Huang Y Carlton J Walker J Barnwell J Beerli P Charleston MA Pybus OG Su XZ 《Molecular biology and evolution》2005,22(8):1686-1693
The geographical origin of Plasmodium vivax, the most widespread human malaria parasite, is controversial. Although genetic closeness to Asian primate malarias has been confirmed by phylogenetic analyses, genetic similarities between P. vivax and Plasmodium simium, a New World primate malaria, suggest that humans may have acquired P. vivax from New World monkeys or vice versa. Additionally, the near fixation of the Duffy-negative blood type (FY x B(null)/FY x B(null)) in West and Central Africa, consistent with directional selection, and the association of Duffy negativity with complete resistance to vivax malaria suggest a prolonged period of host-parasite coevolution in Africa. Here we use Bayesian and likelihood methods in conjunction with cophylogeny mapping to reconstruct the genetic and coevolutionary history of P. vivax from the complete mitochondrial genome of 176 isolates as well as several closely related Plasmodium species. Taken together, a haplotype network, parasite migration patterns, demographic history, and cophylogeny mapping support an Asian origin via a host switch from macaque monkeys. 相似文献
94.
95.
Ren Y Barnwell LF Alexander JC Lubin FD Adelman JP Pfaffinger PJ Schrader LA Anderson AE 《The Journal of biological chemistry》2006,281(17):11769-11779
Small conductance, Ca2+-activated voltage-independent potassium channels (SK channels) are widely expressed in diverse tissues; however, little is known about the molecular regulation of SK channel subunits. Direct alteration of ion channel subunits by kinases is a candidate mechanism for functional modulation of these channels. We find that activation of cyclic AMP-dependent protein kinase (PKA) with forskolin (50 microm) causes a dramatic decrease in surface localization of the SK2 channel subunit expressed in COS7 cells due to direct phosphorylation of the SK2 channel subunit. PKA phosphorylation studies using the intracellular domains of the SK2 channel subunit expressed as glutathione S-transferase fusion protein constructs showed that both the amino-terminal and carboxyl-terminal regions are PKA substrates in vitro. Mutational analysis identified a single PKA phosphorylation site within the amino-terminal of the SK2 subunit at serine 136. Mutagenesis and mass spectrometry studies identified four PKA phosphorylation sites: Ser465 (minor site) and three amino acid residues Ser568, Ser569, and Ser570 (major sites) within the carboxyl-terminal region. A mutated SK2 channel subunit, with the three contiguous serines mutated to alanines to block phosphorylation at these sites, shows no decrease in surface expression after PKA stimulation. Thus, our findings suggest that PKA phosphorylation of these three sites is necessary for PKA-mediated reorganization of SK2 surface expression. 相似文献
96.
Eldin Talundzic Sheila Akinyi Okoth Kanungnit Congpuong Mateusz M. Plucinski Lindsay Morton Ira F. Goldman Patrick S. Kachur Chansuda Wongsrichanalai Wichai Satimai John W. Barnwell Venkatachalam Udhayakumar 《PLoS pathogens》2015,11(4)
The recent emergence of artemisinin resistance in the Greater Mekong Subregion poses a major threat to the global effort to control malaria. Tracking the spread and evolution of artemisinin-resistant parasites is critical in aiding efforts to contain the spread of resistance. A total of 417 patient samples from the year 2007, collected during malaria surveillance studies across ten provinces in Thailand, were genotyped for the candidate Plasmodium falciparum molecular marker of artemisinin resistance K13. Parasite genotypes were examined for K13 propeller mutations associated with artemisinin resistance, signatures of positive selection, and for evidence of whether artemisinin-resistant alleles arose independently across Thailand. A total of seven K13 mutant alleles were found (N458Y, R539T, E556D, P574L, R575K, C580Y, S621F). Notably, the R575K and S621F mutations have previously not been reported in Thailand. The most prevalent artemisinin resistance-associated K13 mutation, C580Y, carried two distinct haplotype profiles that were separated based on geography, along the Thai-Cambodia and Thai-Myanmar borders. It appears these two haplotypes may have independent evolutionary origins. In summary, parasites with K13 propeller mutations associated with artemisinin resistance were widely present along the Thai-Cambodia and Thai-Myanmar borders prior to the implementation of the artemisinin resistance containment project in the region. 相似文献
97.
Cytoadherence and sequestration in falciparum malaria 总被引:5,自引:0,他引:5
J W Barnwell 《Experimental parasitology》1989,69(4):407-412
98.
A mathematical model of a neuron was developed to investigate the effects of various spatio-temporal patterns of miniature dendritic input potentials on neuronal somatic potentials. The model treats spatio-temporal dendritic activation patterns as the input or forcing function in the non-homogeneous cable equation. The theoretical somatic potentials resulting from several different spatio-temporal input patterns were generated on an IBM 360/75 computer. The model allows the investigation of the theoretical effects of activations at several different synaptic sites, of repeated activations at one or more sites, and of changes in various parameters. The time-to-peak and amplitude of individual excitatory postsynaptic potentials, distance of synapses from the soma, and interactivation interval for repeated activations at the same synapse were among the parameters investigated. Not only the order of activations at different synaptic sites was important, but the time intervals between activations were shown to be important. For a given order of activations at different synapses, optimum time intervals between activations were demonstrated, with respect to the resulting peak somatic potentials. Possible consequences of some hypothetical learning and memory mechanisms upon neuronal excitability were discussed. It was also shown that a deterministic model can generate theoretical curves which appear to be almost of a random nature with respect to the observed numbers and amplitudes of peaks of individual EPSPs. The conditions for the appearance of extra peaks were discussed.This paper describes work done as a portion of G.M.B.'s Ph. D. thesis in biomathematics at N.C. State University, and was supported by Public Health Service Grant No. GM-678 from the National Institute of General Medical Sciences. 相似文献
99.
Adriano Barbosa-Silva Theodoros G Soldatos Ivan LF Magalhães Georgios A Pavlopoulos Jean-Fred Fontaine Miguel A Andrade-Navarro Reinhard Schneider J Miguel Ortega 《BMC bioinformatics》2010,11(1):70
Background
Biological knowledge is represented in scientific literature that often describes the function of genes/proteins (bioentities) in terms of their interactions (biointeractions). Such bioentities are often related to biological concepts of interest that are specific of a determined research field. Therefore, the study of the current literature about a selected topic deposited in public databases, facilitates the generation of novel hypotheses associating a set of bioentities to a common context. 相似文献100.