Model complexes with naturally occurring ligands (salicylglycine and imidazol) and the biometals copper and cobalt

Two new complexes [Cu(Imz)(4)Cl(2)][Cu(Imz)(4)Cl] (2)(2-OH-Hip)(2) (1) and [Co(2-OH-Hip)(Imz)(3)].H(2)O (2) (with Imz=Imidazol and 2-OH-Hip=2-hydroxyhippuric acid) were prepared and characterized. The molecular structures and the solution and solid state behavior of the complexes were investigated. Complex 1 crystallizes in the monoclinic space group P2(1)/c with a=16.880(1), b=8.046(1), c=24.683(1) A, beta=107.88(1) degrees, and Z=2, while complex 2 crystallizes in the orthorhombic space group Pbca with a=11.712(2), b=15.741(4), c=22.254(4) A, and Z=8. The [Cu(Imz)(4)Cl(2)][Cu(Imz)(4)Cl](2)(2-OH-Hip)(2) solid consists in two distinct monomeric Cu(II) complexes: one of them is neutral octahedral [Cu(Imz)(4)Cl(2)] and the other, charged square basis pyramida [Cu(Imz)(4)Cl](+). The 2-hydroxyhippuric acid, which here acts as a counter ion, is deprotonated at its carboxylic group. Cobalt(III) ion in [Co(2-OH-Hip)(Imz)(3)].H(2)O is at the center of an octahedral environment, coordinated to three Imidazol ligands and to a triply deprotonated 2-hydroxyhippuric acid molecule acting as a tridentate ligand. Aqueous solution equilibrium of the quaternary system Cu(2+)/2-OH-Hip/Imz/H(+) was studied by potentiometric titrations.     

Mitochondrial DNA lineages of elite Ethiopian athletes

Previous studies have hypothesised that mitochondrial DNA (mtDNA) polymorphisms may influence aerobic performance. The matrilineal inheritance and accumulation of polymorphisms in mtDNA means that mtDNA haplogroups, characterised by key polymorphisms, are often represented at different frequencies in different populations. The present study aimed to compare the mtDNA haplogroup distribution of elite Ethiopian athletes relative to the general Ethiopian population. The haplogroup distribution of 76 endurance athletes (E), members of the Ethiopian national athletics team, was compared to 108 members of the general Ethiopian population (C). DNA was extracted from buccal swabs and haplogroups assigned by sequencing part of the hypervariable sequence (HVS-I), followed by analysis of key coding-region polymorphisms. A high proportion of African 'L' haplogroups was found in athletes and controls (C=53%; E=55%). Haplogroup distribution of endurance runners did not differ from that of C (P=0.63). Elite Ethiopian athletes are not a mitochondrially distinct group relative to the Ethiopian population. It appears that environment and, perhaps, polymorphisms in the nuclear genome are more important determinants of Ethiopian running success than mtDNA polymorphisms.     

The extracellular N terminus of the endothelin B (ETB) receptor is cleaved by a metalloprotease in an agonist-dependent process

The extracellular N terminus of the endothelin B (ET(B)) receptor is susceptible to limited proteolysis (cleavage at R64 downward arrow S65), but the regulation and the functional consequences of the proteolysis remain elusive. We analyzed the ET(B) receptor or an ET(B)-GFP fusion protein stably or transiently expressed in HEK293 cells. After incubation of cells at 4 degrees C, only the full-length ET(B) receptor was detected at the cell surface. However, when cells were incubated at 37 degrees C, N-terminal cleavage was observed, provided endothelin 1 was present during the incubation. Cleavage was not inhibited by internalization inhibitors (sucrose, phenylarsine oxide). However, in cells incubated with both internalization inhibitors and metalloprotease inhibitors (batimastat, inhibitor of TNFalpha-convertase) or metal chelators (EDTA, phenanthroline), the cleavage was blocked, indicating that metalloproteases cleave the agonist-occupied ET(B) receptor at the cell surface. Functional analysis of a mutant ET(B) receptor lacking the first 64 amino acids ([Delta2-64]ET(B) receptor) revealed normal functional properties, but a 15-fold reduced cell surface expression. The results suggest a role of the N-terminal proteolysis in the regulation of cell surface expression of the ET(B) receptor. This is the first example of a multispanning membrane protein, which is cleaved by a metalloprotease, but retains its functional activity and overall structure.     

Structural polymorphism of the RecA protein from the thermophilic bacterium Thermus aquaticus.

The Escherichia coli RecA protein has served as a model for understanding protein-catalyzed homologous recombination, both in vitro and in vivo. Although RecA proteins have now been sequenced from over 60 different bacteria, almost all of our structural knowledge about RecA has come from studies of the E. coli protein. We have used electron microscopy and image analysis to examine three different structures formed by the RecA protein from the thermophilic bacterium Thermus aquaticus. This protein has previously been shown to catalyze an in vitro strand exchange reaction at an optimal temperature of about 60 degrees C. We show that the active filament formed by the T. aquaticus RecA on DNA in the presence of a nucleotide cofactor is extremely similar to the filament formed by the E. coli protein, including the extension of DNA to a 5.1-A rise per base pair within this filament. This parameter appears highly conserved through evolution, as it has been observed for the eukaryotic RecA analogs as well. We have also characterized bundles of filaments formed by the T. aquaticus RecA in the absence of both DNA and nucleotide cofactor, as well as hexameric rings of the protein formed under all conditions examined. The bundles display a very large plasticity of mass within the RecA filament, as well as showing a polymorphism in filament-filament contacts that may be important to understanding mutations that affect surface residues on the RecA filament.     

Linkage disequilibrium of three polymorphic RFLP markers in the apolipoprotein AI-CIII gene cluster on chromosome 11

A panel of glial tumors consisting of 11 low grade gliomas, 9 anaplastic gliomas, and 29 glioblastomas were analyzed for loss of heterozygosity by examining at least one locus for each chromosome. The frequency of allele loss was highest among the glioblastomas, suggesting that genetic alterations accumulate during glial tumor development. The most common genetic alteration detected involved allele losses of chromosome 10 loci; these losses were observed in all glioblastomas and in three of the anaplastic gliomas. In order to delineate which chromosome 10 region or regions were deleted in association with glial tumor development, a deletion mapping analysis was performed, and this revealed the partial loss of chromosome 10 in eight glioblastomas and two of the anaplastic gliomas. Among these cases, three distinct regions of chromosome 10 were indicated as being targeted for deletion: one telomeric region on 10p and both telomeric and centromeric locations on 10q. These data suggest the existence of multiple chromosome 10 tumor suppressor gene loci whose inactivation is involved in the malignant progression of glioma.     

Effect of cytidine diphosphate choline (CDP-choline) on ischemia-induced alterations of brain lipid in the gerbil

Brain ischemia was produced in gerbils (Meriones unguiculatus) by the bilateral ligation of the carotid arteries. Definite changes in the energy status of brain demonstrated that carotid occlusion was effective. Five minutes before ligation, an intraventricular injection of either saline or cytidine diphosphate choline (CDP-choline, 0.6 mol/brain, 3l) was given to groups of animals. Control animals, with and without CDP-choline, together with the ischemic groups, were decapitated directly into liquid nitrogen; 10 min after arterial ligation. Brain free fatty acids, neutral lipids and phospholipids, which were labeled in vivo by the intraventricular injection of [1-¹⁴C] arachidonic acid (0.4–0.6 Ci, 6–9 nmol) 2 hr prior to ligation, were extracted, purified, and separated by thin-layer chromatographic procedures. The CDP-choline treatment noticeably corrected the increase of total and individual fatty acids due to ischemia and the increase of their radioactivity content. The changes in neutral lipids, particularly in the diacyl glycerol fraction, were also corrected by the injection of the nucleotide. CDP-choline partially reversed the decrease of brain phosphatidylcholine and of its labeling, which was due to ischemia. All the data indicate that the prior injection of CDP-choline stimulates the choline phosphotransferase reaction of brain towards synthesis of phosphatidylcholine and prevents the release of free fatty acids, particularly of arachidonic acid, associated with ischemia.     

Analysis of X-chromosome inactivation in X-linked immunodeficiency with hyper-IgM (HIGM1): evidence for involvement of different hematopoietic cell lineages

Summary The pattern of X-chromosome inactivation was analyzed, by means of two different DNA probes (pSPT-PGK and M27), in several cell lineages derived from females belonging to a pedigree with X-linked immunodeficiency with hyper-IgM (HIGM1). Non-random X-chromosome inactivation was demonstrated in T cells, B cells, and neutrophils, but not in fibroblasts, of obligate carriers, suggesting that different hematopoietic cell lineages are primarily involved in HIGM1. Preferential inactivation of the paternally derived X-chromosome was demonstrated by analysis of segregation of the alleles defined by the pSPT-PGK and M27 probes. The possibility that the HIGM1 mutation may confer a proliferative and/or differential advantage to hematopoietic precursors carrying the mutated allele on the active X-chromosome is discussed.     

Fun&Co: identification of key functional differences in transcriptomes

MOTIVATION: Microarray and other genome-wide technologies allow a global view of gene expression that can be used in several ways and whose potential has not been yet fully discovered. Functional insight into expression profiles is routinely obtained by using gene ontology terms associated to the cellular genes. In this article, we deal with functional data mining from expression profiles, proposing a novel approach that studies the correlations between genes and their relations to Gene Ontology (GO). We implemented this approach in a public web-based application named Fun&Co. By using Fun&Co, the user dissects in a pair-wise manner gene expression patterns and links correlated pairs to gene ontology terms. The proof of principle for our study was accomplished by dissecting molecular pathways in muscles. In particular, we identified specific cellular pathways by comparing the three different types of muscle in a pairwise fashion. In fact, we were interested in the specific molecular mechanisms regulating the cardiovascular system (cardiomyocytes and smooth muscle cells). RESULTS: We applied here Fun&Co to the molecular study of cardiovascular system and the identification of the specific molecular pathways in heart, skeletal and smooth muscles (using 317 microarrays) and to reveal functional differences between the three different kinds of muscle cells. AVAILABILITY: Application is online at http://tommy.unife.it. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.