Mitochondrial membrane permeabilization by HIV-1 Vpr

The mitochondrion is a privileged target for apoptosis-modulatory proteins of viral origin. Thus, viral protein R (Vpr) can target mitochondria and induce apoptosis via a specific interaction with the permeability transition pore complex (PTPC). Vpr cooperates with the adenine nucleotide translocator (ANT) to form large conductance channels and to trigger all the hallmarks of mitochondrial membrane permeabilization (MMP). The Vpr/ANT interaction is direct, since it is abolished by the addition of a peptide corresponding to the Vpr binding site of ANT, ADP, ATP, or by Bcl-2. Accordingly, Vpr modulates MMP through direct structural and functional interactions with PTPC proteins.     

Use of reversed phase HP liquid chromatography to assay conversion of N-acylglycines to primary fatty acid amides by peptidylglycine-alpha-amidating monooxygenase

Primary fatty acid amides (R-CO-NH2) and N-acylglycines (R-CO-NH-CH2-COOH) are classes of compounds that have only recently been isolated and characterized from biological sources. Key questions remain regarding how these lipid amides are produced and degraded in biological systems. Relative to the fatty acids, little has been done to develop methods to separate and quantify the fatty acid amides and N-acylglycines. We describe reversed phase HPLC methods for the separation of C2-C12 primary fatty acid amides and N-acylglycines and also C12-C22 fatty acid amides. Separation within each class occurs primarily on the basis of simple interactions between the acyl chain and the chromatographic stationary phase, but the polar headgroups on these and related fatty acids and N-acylethanolamides modulate the absolute retention in reversed phase mode. We use these methods to measure the enzyme-mediated, two-step conversion of N-octanoylglycine to octanoamide.     

A molecular and karyological approach to the taxonomy of Nautilus

Nautiloids, the externally shelled cephalopods of Cambrian origin, are the most ancient lineage among extant cephalopods. Their ancestral characters are explored based on morphological and molecular data (18S rDNA sequence) to investigate the evolution of present cephalopod lineages. Among molluscs, nautilus 18S rDNA gene is the longest reported so far, due to large nucleotidic insertions. By comparison with other 18S sequences, the complete gene of N. macromphalus helps to clarify the taxonomic status of the three universally recognised Nautilus species. The range of interspecific molecular differences supports separation of the present species into two surviving ectocochleate genera, Nautilus and Allonautilus. Nautiloid 18S is considered as corresponding to the ancestral form of 18S as is the number of chromosomes in Nautilus (52), the lowest among cephalopods. Comparison of karyological characteristics amongst cephalopods in a phylogenetic context suggests a possible correlation between duplication events and lineage divergence.     

Iron-superoxide dismutase and monodehydroascorbate reductase transcripts accumulate in response to internode rubbing in tomato

A cDNA encoding an iron-superoxide dismutase (Fe-SOD) was isolated by RACE-PCR from a Lycopersicon esculentum cDNA library. The Fe-SOD cDNA consists of a 746-bp open reading frame and is predicted to encode a protein of 249 amino acids with a calculated molecular mass of 27.9 kDa. The deduced amino acid sequence was very similar to other plant Fe-SODs and a potential chloroplastic targeting was found. To study the induction of oxidative burst in response to mechanical stimulation, the accumulation of Fe-SOD and monodehydroascorbate reductase (MDHAR) mRNAs was analysed in response to young growing internode rubbing in tomato plants. Northern analyses show that Fe-SOD mRNA and MDHAR mRNA accumulated in tomato internodes 10 min after the mechanical stimulation. These results suggest that reactive oxygen species are early involved in the response of a plant to a mechanical stimulation, such as rubbing. The nucleotide sequence data reported in this paper will appear in the NCBI Nucleotide Sequence Databases under the accession number AY262025.     

Genetic and molecular basis of grass cell wall biosynthesis and degradability. II. Lessons from brown-midrib mutants

The brown-midrib mutants of maize have a reddish-brown pigmentation of the leaf midrib and stalk pith, associated with lignified tissues. These mutants progressively became models for lignification genetics and biochemical studies in maize and grasses. Comparisons at silage maturity of bm1, bm2, bm3, bm4 plants highlighted their reduced lignin, but also illustrated the biochemical specificities of each mutant in p-coumarate, ferulate ester and etherified ferulate content, or syringyl/guaiacyl monomer ratio after thioacidolysis. Based on the current knowledge of the lignin pathway, and based on presently developed data and discussions, C3H and CCoAOMT activities are probably major hubs in controlling cell-wall lignification (and digestibility). It is also likely that ferulates arise via the CCoAOMT pathway.     

In silico comparative analysis reveals a mosaic conservation of genes within a novel colinear region in wheat chromosome 1AS and rice chromosome 5S

Comparative RFLP mapping has revealed extensive conservation of marker order in different grass genomes. However, microcolinearity studies at the sequence level have shown rapid genome evolution and many exceptions to colinearity. Most of these studies have focused on a limited size of genomic fragment and the extent of microcolinearity over large distances or across entire genomes remains poorly characterized in grasses. Here, we have investigated the microcolinearity between the rice genome and a total of 1,500 kb from physical BAC contigs on wheat chromosome 1AS. Using ESTs mapped in wheat chromosome bins as an additional source of physical data, we have identified 27 conserved orthologous sequences between wheat chromosome 1AS and a region of 1,210 kb located on rice chromosome 5S. Our results extend the orthology described earlier between wheat chromosome group 1S and rice chromosome 5S. Microcolinearity was found to be frequently disrupted by rearrangements which must have occurred after the divergence of wheat and rice. At the Lr10 orthologous loci, microrearrangements were due to the insertion of mobile elements, but also originated from gene movement, amplification, deletion and inversion. These mechanisms of genome evolution are at the origin of the mosaic conservation observed between the orthologous regions. Finally, in silico mapping of wheat genes identified an intragenomic colinearity between fragments from rice chromosome 1L and 5S, suggesting an ancestral segmental duplication in rice.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

An in vitro dual model of mycobacterial granulomas to investigate the molecular interactions between mycobacteria and human host cells

In the majority of individuals infected with Mycobacterium tuberculosis, the bacilli cause a long-term asymptomatic infection called latent tuberculosis, a state during which the bacilli reside within granulomas. Latently infected individuals have around 10% risk of progression to clinical disease at a later stage. Determining the state of the mycobacteria and the host cells during this latent phase, i.e. within the granulomas, would greatly improve our understanding of the physiopathology of tuberculosis, and thus enable the development of new therapeutic means to treat the one-third of the world's population who are latently infected. We have developed an in vitro model of human mycobacterial granulomas, enabling the cellular and molecular analysis of the very first steps in the host granulomatous response to either mycobacterial compounds or live mycobacterial species. In vitro mycobacterial granulomas mimic natural granulomas very well, with the progressive recruitment of macrophages around live bacilli or mycobacterial antigen-coated beads, their differentiation into multinucleated giant cells and epithelioid cells, and the final recruitment of a ring of activated lymphocytes. Besides morphological similarities, in vitro granulomas also functionally resemble natural ones, with the development of intense cellular co-operation and intracellular mycobactericidal activities.     

Preferential expression of a plant cystatin at nematode feeding sites confers resistance to Meloidogyne incognita and Globodera pallida

The expression patterns of three promoters preferentially active in the roots of Arabidopsis thaliana have been investigated in transgenic potato plants in response to plant parasitic nematode infection. Promoter regions from the three genes, TUB-1, ARSK1 and RPL16A were linked to the GUS reporter gene and histochemical staining was used to localize expression in potato roots in response to infection with both the potato cyst nematode, Globodera pallida and the root-knot nematode, Meloidogyne incognita. All three promoters directed GUS expression chiefly in root tissue and were strongly up-regulated in the galls induced by feeding M. incognita. Less activity was associated with the syncytial feeding cells of the cyst nematode, although the ARSK1 promoter was highly active in the syncytia of G. pallida infecting soil grown plants. Transgenic potato lines that expressed the cystatin OcIDeltaD86 under the control of the three promoters were evaluated for resistance against Globodera sp. in a field trial and against M. incognita in containment. Resistance to Globodera of 70 +/- 4% was achieved with the best line using the ARSK1 promoter with no associated yield penalty. The highest level of partial resistance achieved against M. incognita was 67 +/- 9% using the TUB-1 promoter. In both cases this was comparable to the level of resistance achieved using the constitutive cauliflower mosaic virus 35S (CaMV35S) promoter. The results establish the potential for limiting transgene expression in crop plants whilst maintaining efficacy of the nematode defence.     

Homozygosity for a missense mutation in the 67 kDa isoform of glutamate decarboxylase in a family with autosomal recessive spastic cerebral palsy: parallels with Stiff-Person Syndrome and other movement disorders

Background  

Cerebral palsy (CP) is an heterogeneous group of neurological disorders of movement and/or posture, with an estimated incidence of 1 in 1000 live births. Non-progressive forms of symmetrical, spastic CP have been identified, which show a Mendelian autosomal recessive pattern of inheritance. We recently described the mapping of a recessive spastic CP locus to a 5 cM chromosomal region located at 2q24-31.1, in rare consanguineous families.