Interactions between Zn and Cu in LEC rats, an animal model of Wilson's disease

The effect of oral Zn treatment was studied in the liver and kidneys of 26 male Long-Evans Cinnamon (LEC) rats (mutant animals, 5 weeks old) in relation to both the interaction between Zn and Cu and the localisation and concentration of metallothionein (MT). Rats receiving 80 mg zinc acetate daily by gavage and control rats receiving no treatment were killed after 1 or 2 weeks. By immunohistochemical and analytical chemical techniques we revealed that treated rats had higher levels of MT in the hepatic and renal cells compared to untreated ones. Tissue Zn concentrations were significantly higher in treated rats compared to untreated whereas Cu concentrations decreased in the liver and kidneys as indicated by analytical chemical analyses. MT levels also decreased with treatment period. A histochemical procedure, obtained using autofluorescence of Cu-metallothioneins, confirms these findings: after 2 weeks, the signal decreased in both the liver and kidney sections. This gives a greater understanding of the mechanism of Cu metabolism in the two tissues considered. These results suggest that Zn acts both to compete for absorption on the luminal side of the intestinal epithelium and to induce the synthesis of MT.     

NMR spectroscopic and theoretical study of the complexation of the inhibitor allosamidin in the binding pocket of the plant chitinase hevamine

Based on NMR spectroscopic information about the allosamidin-hevamine complex, ab initio MO calculations of the ring current effect of the aromatic moieties of Trp255, Tyr183 and Tyr6 of hevamine were carried out to investigate the role of these amino acid residues in binding interactions with allosamidin in solution. In addition, the intermolecular steric compression effect on the 13C chemical shifts of the allosamizoline carbon atoms and the hydrogen bonding to Glu127 was identified. It can be inferred that the binding forces are strongest in the allosamizoline moiety of allosamidin.     

Interaction of linear and cyclic peptide antagonists at the human B(2) kinin receptor

The ligand receptor interactions involving the C-terminal moiety of kinin B(2) receptor antagonists Icatibant (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-Dtic-Oic-Arg-OH), MEN 11270 (H-DArg-Arg-Pro-Hyp-Gly-Thi-c(Dab-Dtic-Oic-Arg)c(7gamma-10alpha)) and a series of analogs modified in position 10 were investigated by radioligand-binding experiments at the wild type (WT) and at the Ser(111)Ala and Ser(111)Lys mutant human kinin B(2) receptors. Icatibant and [Lys(10)]-Icatibant maintained the same high affinity towards the three receptors. For Icatibant-NH(2), [Ala(10)]-Icatibant, MEN 11270 and [Glu(10)]-MEN 11270, the changes in affinity at the WT and Ser(111)Lys receptors indicated that the presence of a net positive or negative charge at the C-terminal moiety of these peptides caused a decrease in affinity to the WT receptor and that Ser(111) residue is in proximity of the side chain of residue 10. The changes in affinity measured with [desArg(10)]-Icatibant and [desArg(10)]-Icatibant-NH(2), moreover, confirmed that a C-terminal charge compensation between the positive charge of Arg(10) side chain and the C-terminal free carboxylic function favours a high affinity interaction.     

Cloning,functional expression and expression studies of the nitrate transporter gene from Chlorella sorokiniana (strain 211-8k)

The nitrate transporter from Chlorella sorokiniana (accession number AY026523) has been cloned by screening a cDNA library based on mRNA isolated after 30 min treatment of Chlorella with 5 mM nitrate and with a RT-PCR product (730 bp) as a probe. The Chlorella sequence has similarity to known nitrate transporters of the NRT2 family (high-affinity nitrate transporters). The cDNA clone was used for functional expression in Xenopus oocytes and a nitrate-dependent current was measured at pH 5.5 but not at pH 7.4. A second algal gene or a second gene product was not needed for functional expression in Xenopus. Inhibitor studies in Chlorella indicated that protein phosphorylation/dephosphorylation is involved in nitrate induction of ChNRT2.1. In addition to nitrate, ChNRT2.1 expression is induced by nitroprusside, a NO donor, and is affected by glucose.     

Variability of HXT2 at the protein and gene level among the Saccharomyces sensu stricto group

Variability of HXT2 at the protein and gene level was investigated among Saccharomyces sensu stricto and other yeast species. Results showed that the HXT2 gene is probably present in yeast genera other than Saccharomyces, suggesting that this gene is widely distributed in the yeast world. Chromosomal analyses indicated the stable location of HXT2 on the same chromosome and with the same copy number throughout the entire sensu stricto group. Results of the immunoblotting assay demonstrated that all strains tested (with the exception of S. cerevisiae DBVPG 6042) exhibited a lower level of Hxt2p expression than that shown by laboratory wild-type. Moreover, Hxt2p expression seems to reinforce the taxonomical differences between the two pairs of species (S. cerevisiae and S. paradoxus vs. S. pastorianus and S. bayanus) within the sensu stricto group of the genus of Saccharomyces that also reflect their different ecological niche.     

A new HPLC-ELSD method to quantify indican in Polygonum tinctorium L. and to evaluate beta-glucosidase hydrolysis of indican for indigo production

A method to quantify the indigo precursor indican (indoxyl-beta-D-glucoside) in Polygonum tinctorium L. has been developed. Plant material was extracted in deionized water, and indican was identified and quantified using high performance liquid chromatography (HPLC) coupled to an evaporative light scattering detector (ELSD). Results confirmed that with this method it is possible to measure indican content in a short time, obtaining reliable and reproducible data. Using this method, leaf indican content was quantified every 15 days during the growing season (from May to October) in P. tinctorium crops grown in a field experiment in Central Italy. Results showed that indican increased along the growing season until flowering and was positively affected by photosynthetic active radiation (PAR). Indican is naturally hydrolyzed by native beta-glucosidase to indoxyl and glucose, the indoxyl yielding indigo. The activity of two enzymes, sweet almond beta-glucosidase and Novarom G preparation, were compared with P. tinctorium native beta-glucosidase to evaluate indigo production. Results showed that the ability to promote indigo formation increased as follows: almond beta-glucosidase 相似文献   

In vivo and in vitro effects of cadmium on H+ ATPase activity of plasma membrane vesicles from oat (Avena sativa L.) roots

The effect of an in vivo and in vitro treatment with cadmium on transport activities of root plasma membrane enriched vesicles was studied in oat (Avena sativa L. cv. Argentina) plants. Addition of 100 mumol/L CdSO4 to nutrient solution decreases both proton transport activity and ATPase activity to the same level. In vitro experiments show that cadmium seems to have a differential inhibiting effect on proton transport activity and ATPase activity, the most pronounced one on ATP-dependent H(+)-accumulation, suggesting that cadmium would interfere with membrane permeability properties. This is indeed the case. The results demonstrate that cadmium decreases passive permeability to protons.     

Morphological and biochemical modifications induced by a static magnetic field on Fusarium culmorum

The effects of the exposure to a static magnetic field (sMF) of 0.3 +/- 0.03 T on the Fusarium culmorum were investigated in vitro. sMF inhibition of mycelia growth was accompanied by morphological and biochemical changes. Fungal conidia germination and cell viability were also reduced. We provide evidence of the influence of sMF on Ca(2+)-dependent signal transduction pathways involved in conidia germination. Perturbation of these pathways by adding different compounds (i.e. CaCl(2), phorbol 12-myristate 13-acetate, neomycin, EGTA, LiCl) to the medium, suggested that exposed conidia are unable to mobilise calcium from intracellular stores and that the hindered mechanism may be IP(3)-dependent.     

What can rodent models tell us about cognitive decline in Alzheimer's disease?

The prolongation of life and the rapidly increasing incidence of Alzheimer's disease have brought to the foreground the need for greater understanding of the etiology of the disease and the means to prevent or at least slow down the process. Out of this need the transgenic mouse and the production of synthetic amyloid peptides have been developed in an attempt to create experimental models of Alzheimer's disease that will help our understanding of the cellular and molecular mechanisms by which the pathology leads to memory dysfunction and to test potential therapeutic strategies. Despite 10 or so years of reasonably intensive research with these models, both fall short of producing a viable and faithful model of the complete pathology of Alzheimer's disease and the behavioral consequences are far from modelling the progressive decline in cognitive function. Here we review the advantages and the caveats associated with the two models in terms of the pathology, the associated memory dysfunction, and the effect on synaptic plasticity. Given the more recent advances that have been made in the understanding of the neurobiological changes that occur with the disease and with the consideration of other environmental effects, which have been clearly shown to have an impact on the progression of the disease in humans, we emphasis the advantage of pharmacological or environmental in transgenic mice or rodents injected with synthetic peptides that may prove to be more fruitful in our understanding of the memory deficits associated with the disease.