Comparison of the solution and crystal structures of mitochondrial cytochrome c. Analysis of paramagnetic shifts in the nuclear magnetic resonance spectrum of ferricytochrome c

The two accompanying papers describe the assignment of methyl-containing spin-systems in the 1H nuclear magnetic resonance spectra of tuna ferricytochrome c and tuna ferrocytochrome c. At present, 104 resonances from 208 C-H protons are assigned in both oxidation states. In this paper, the difference in chemical shift of a resonance between the two oxidation states is used together with a dipolar model of the unpaired electron spin of ferricytochrome c to compare the structure of cytochrome c in solution with three high-resolution structures of cytochrome c obtained by X-ray diffraction in single crystals. The overall protein fold and the positions of most of the haem-packing residues are shown to be invariant between the crystal and solution. However, three regions of the protein, at the C terminus, around the haem propionic acid groups and at the haem crevice near thioether-2, are found to undergo conformational changes on the removal of crystal packing constraints.     

Revisiting the use of Iprodione and Trichoderma in the integrated management of onion white rot

The biocontrol properties of Trichoderma species are well documented, but their effectiveness in antagonism of the problematic Sclerotium cepivorum, the causal agent of white rot in Allium species, appears limited with reports of significant control only relating to deliberately-mutated strains of Trichoderma. Our previous studies have indicated the possibility of using selected naturally-occurring strains of the antagonist in the suppression of other diseases; now in vitro and controlled environment in vivo studies have indicated that a degree of control of Onion White Rot is possible, and that the selected antagonist strains can be used in integrated treatments with Iprodione to good effect. The possible value of such treatments is considered in light of other approaches to the suppression of this continuing problem.     

Principal Networks

Graph representations of brain connectivity have attracted a lot of recent interest, but existing methods for dividing such graphs into connected subnetworks have a number of limitations in the context of neuroimaging. This is an important problem because most cognitive functions would be expected to involve some but not all brain regions. In this paper we outline a simple approach for decomposing graphs, which may be based on any measure of interregional association, into coherent “principal networks”. The technique is based on an eigendecomposition of the association matrix, and is closely related to principal components analysis. We demonstrate the technique using cortical thickness and diffusion tractography data, showing that the subnetworks which emerge are stable, meaningful and reproducible. Graph-theoretic measures of network cost and efficiency may be calculated separately for each principal network. Unlike some other approaches, all available connectivity information is taken into account, and vertices may appear in none or several of the subnetworks. Subject-by-subject “scores” for each principal network may also be obtained, under certain circumstances, and related to demographic or cognitive variables of interest.     

A web server to locate periodicities in a sequence

Summary : FT is a tool written in C++, which implements the Fourier analysis method to locate periodicities in aminoacid or DNA sequences. It is provided for free public use on a WWW server with a Java interface. Availability : The server address is http://o2.db. uoa.gr/FT Contact : shamodr@atlas.uoa.gr      

Aids and adaptations for the elderly at home: underprovided,underused, and undermaintained

A random sample of 140 elderly people aged over 75 was selected from the age-sex register of an urban general practice to assess the provision and use of aids and adaptations in their homes. Many of the aids that the elderly had were faulty, including half of the walking aids and 15% of hearing aids, reading spectacles, and dentures, and up to half of the aids were not used. Yet despite this underuse there were many disabled elderly people who required aids for the bath and toilet.When screening of elderly people is carried out in general practice assessment of aids and adaptations should be included to see that they are provided where needed, are used, and are adequately maintained.     

Utility of the white gene in estimating phylogenetic relationships among mosquitoes (Diptera: Culicidae)

The utility of a nuclear protein-coding gene for reconstructing phylogenetic relationships within the family Culicidae was explored. Relationships among 13 species representing three subfamilies and nine genera of Culicidae were analyzed using a 762-bp fragment of coding sequence from the eye color gene, white. Outgroups for the study were two species from the sister group Chaoboridae. Sequences were determined from clone PCR products amplified from genomic DNA, and aligned following conceptual intron splicing and amino acid translation. Third codon positions were characterized by high levels of divergence and biased nucleotide composition, the intensity and direction of which varied among taxa. Equal weighting of all characters resulted in parsimony and neighboring-joining trees at odds with the generally accepted phylogenetic hypothesis based on morphology and rDNA sequences. The application of differential weighting schemes recovered the traditional hypothesis, in which the subfamily Anophelinae formed the basal clade. The subfamily Toxorhynchitinae occupied an intermediate position, and was a sister group to the subfamily Culicinae. Within Culicinae, the genera Sabethes and Tripteroides formed an ancestral clade, while the Culex-Deinocerites and Aedes- Haemagogus clades occupied increasingly derived positions in the molecular phylogeny. An intron present in the Culicinae- Toxorhynchitinae lineage and one outgroup taxon was absent in the basal Anophelinae lineage and the second outgroup taxon, suggesting that intron insertions or deletions may not always be reliable systematic characters.