Treatment of superficial cancerous tumors by hyperthermia induced by ultrasonics or microwaves

Results of treating superficial human cancerous tumors by ultrasound (1-3 MHz) or microwave (434 MHz) hyperthermia, alone or combined with radiotherapy or chemotherapy are presented according to the heating method. The comparison of in vivo thermal distributions obtained at depth with these two techniques could partially explain their different therapeutic efficiency.     

Characterization of a putative type IV aminophospholipid transporter P-type ATPase

The P-type ATPases comprise a well-studied family of proteins involved in the active transport of charged substrates across biological membranes. Starting from a mouse bone marrow-derived macrophage cDNA library and using a signal peptide trapping strategy, we identified a new P-type ATPase family member. We characterized the genomic structure of this gene, named Atp10d, as well as its human counterpart. The presence of P-type ATPase consensus motifs and phylogenetic analysis showed that this gene is a member of the type IV, putative amphipath transporters subfamily. We showed that this gene is expressed in kidney and placenta. We also found that the C57BL/6 strain carries a constitutive stop codon in the sequence of Atp10d exon 12, whereas 14 other inbred mouse strains show an uninterrupted reading frame at this location. This mutation in C57BL/6 should lead to a non-functional protein, suggesting that this gene may not be essential. We discuss the involvement of the Atp10d gene in the fat-prone phenotype of the C57BL/6 strain and its physical mapping within a QTL associated with HDL-cholesterol levels.     

High pressure disruption: a two-step treatment for selective extraction of intracellular components from the microalga Porphyridium cruentum

The microalga Porphyridium cruentum is known to produce many components of interest. One of them is B-Phycoerythrin (B-PE), a water-soluble intracellular pigment used as an immunofluorescent probe. Current methods to extract this molecule involve total cell disruption and lead to a mix of all the water-soluble components. Subsequently, the pigment purification is very complex. An alternative approach to extract B-PE selectively and thus simplify the purification procedure has been developed using a high-pressure cell disrupter. Different pressures (from 27 to 270 MPa), extracting mediums (distilled water and original microalgae culture medium), and numbers of passages (1 to 3) have been tested. Proteins are selectively more extracted than B-PE at low pressure in original medium. It is thus possible to remove part of the intracellular proteins in a first step and then recover enriched B-Phycoerythrin fraction at higher pressure in distilled water.     

Apo and holo crystal structures of an NADP-dependent aldehyde dehydrogenase from Streptococcus mutans.

The aldehyde dehydrogenases (ALDHs) are a superfamily of multimeric enzymes which catalyse the oxidation of a broad range of aldehydes into their corresponding carboxylic acids with the reduction of their cofactor, NAD or NADP, into NADH or NADPH. At present, the only known structures concern NAD-dependent ALDHs. Three structures are available in the Protein Data Bank: two are tetrameric and the other is a dimer. We solved by molecular replacement the first structure of an NADP-dependent ALDH isolated from Streptococcus mutans, in its apo form and holo form in complex with NADP, at 1.8 and 2.6 A resolution, respectively. Although the protein sequence shares only approximately 30 % identity with the other solved tetrameric ALDHs, the structures are very similar. However, a large local conformational change in the region surrounding the 2' phosphate group of the adenosine moiety is observed when the enzyme binds NADP, in contrast to the NAD-dependent ALDHs.Structure and sequence analyses reveal several properties. A small number of residues seem to determine the oligomeric state. Likewise, the nature (charge and volume) of the residue at position 180 (Thr in ALDH from S. mutans) determines the cofactor specificity in comparison with the structures of NAD-dependent ALDHs. The presence of a hydrogen bond network around the cofactor not only allows it to bind to the enzyme but also directs the side-chains in a correct orientation for the catalytic reaction to take place. Moreover, a specific part of this network appears to be important in substrate binding. Since the enzyme oxidises the same substrate, glyceraldehyde-3-phosphate (G3P), as NAD-dependent phosphorylating glyceraldehyde-3-phosphate dehydrogenases (GAPDH), the active site of GAPDH was compared with that of the S. mutans ALDH. It was found that Arg103, Arg283 and Asp440 might be key residues for substrate binding.     

Nucleosomes affect local transformation efficiency

Genetic transformation is a natural process during which foreign DNA enters a cell and integrates into the genome. Apart from its relevance for horizontal gene transfer in nature, transformation is also the cornerstone of today''s recombinant gene technology. Despite its importance, relatively little is known about the factors that determine transformation efficiency. We hypothesize that differences in DNA accessibility associated with nucleosome positioning may affect local transformation efficiency. We investigated the landscape of transformation efficiency at various positions in the Saccharomyces cerevisiae genome and correlated these measurements with nucleosome positioning. We find that transformation efficiency shows a highly significant inverse correlation with relative nucleosome density. This correlation was lost when the nucleosome pattern, but not the underlying sequence was changed. Together, our results demonstrate a novel role for nucleosomes and also allow researchers to predict transformation efficiency of a target region and select spots in the genome that are likely to yield higher transformation efficiency.