B-cell factor 1 is required for optimal expression of the DRA promoter in B cells.

The X box in the DRA promoter of the human histocompatibility complex is required for expression of the DRA gene in B cells. We show that a B-cell factor binds to a sequence that is clearly distinguishable from binding sites for the previously described X box binding nuclear proteins RF-X, NF-X, NF-Xc, NF-S, hXBP, and AP-1. Mutations in the DRA X box that disrupt the binding of this factor result in a lower level of gene expression, as does the presence of Id (a trans-dominant regulatory protein that negatively regulates helix-loop-helix proteins). Furthermore, this factor is recognized by antibodies directed against the helix-loop-helix protein A1, a mouse homolog of the immunoglobulin enhancer binding proteins E12/E47, and it binds to sequences in other genes that were previously shown to bind these proteins. By these criteria, this factor is BCF-1.     

Potato cysteine proteinase inhibitor gene family: molecular cloning,characterisation and immunocytochemical localisation studies

Potato cysteine proteinase inhibitors (PCPIs) represent a distinct group of proteins as they show no homology to any other known cysteine proteinase inhibitor superfamilies, but they all belong to the Kunitz-type soybean trypsin inhibitor family. cDNA clones for five PCPIs have been isolated and sequenced. Amino acid substitutions occurring in the limited regions forming loops on the surface of these proteins suggest a further classification of PCPIs into three subgroups. Accumulation of PCPI was observed in vacuoles of stems after treatment with jasmonic acid (JA) using immunocytochemical localisation, implying that these inhibitors are part of a potato defence mechanism against insects and pathogens. Genomic DNA analysis show that PCPIs form a multigene family and suggest that their genes do not possess any introns.     

Growth and shape transformations of giant phospholipid vesicles upon interaction with an aqueous oleic acid suspension

The interaction of two types of vesicle systems was investigated: micrometer-sized, giant unilamellar vesicles (GUVs) formed from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and submicrometer-sized, large unilamellar vesicles (LUVs) formed from oleic acid and oleate, both in a buffered aqueous solution (pH 8.8). Individual POPC GUVs were transferred with a micropipette into a suspension of oleic acid/oleate LUVs, and the shape changes of the GUVs were monitored using optical microscopy. The behavior of POPC GUVs upon transfer into a 0.8 mM suspension of oleic acid, in which oleic acid/oleate forms vesicular bilayer structures, was qualitatively different from the behavior upon transfer into a 0.3 mM suspension of oleic acid/oleate, in which oleic acid/oleate is predominantly present in the form of monomers and possibly non-vesicular aggregates. In both cases, changes in vesicle morphology were observed within tens of seconds after the transfer. After an initial increase of the vesicle cross-section, the vesicle started to evaginate, spawning dozens of satellite vesicles connected to the mother vesicle with narrow necks or tethers. In 60% of the cases of transfer into a 0.8 mM oleic acid suspension, the evagination process reversed and proceeded to the point where the membrane formed invaginations. In some of these cases, several consecutive transitions between invaginated and evaginated shapes were observed. In the remaining 40% of the cases of transfer into the 0.8 mM oleic acid suspension and in all cases of vesicle transfer into the 0.3 mM oleic acid suspension, no invaginations nor subsequent evaginations were observed. An interpretation of the observed vesicle shape transformation on the basis of the bilayer-couple model is proposed, which takes into account uptake of oleic acid/oleate molecules by the POPC vesicles, oleic acid flip-flop processes and transient pore formation.     

Origins of Allium ampeloprasum horticultural groups and a molecular phylogeny of the section Allium (Allium: Alliaceae)

The subgenus Allium section Allium includes economically important species, such as garlic and leek, as well as other polyploid minor crops. Phylogenetic studies within this section, with a focus on horticultural groups within A. ampeloprasum, were performed on 31 accessions of 17 species using the nuclear ribosomal DNA internal transcribed spacer (ITS) region and the chloroplast trnL-F and trnD-T regions. The results confirmed the monophyly of section Allium. Four main clades were identified on all ITS analyses but the relationships among those and the remaining species studied within section Allium remained unresolved. Trees based on cpDNA recovered two major clades and a topology only partly congruent with that of the ITS tree. Intra-individual polymorphism of the ITS region proved useful in tracking putative parent species of polyploid taxa. The allopolyploid origin of great headed garlic (GHG), A. iranicum and A. polyanthum was confirmed. No signs of hybridization in leek or kurrat were detected but possible introgression events were identified in pearl onion and bulbous leek. Although GHG is often used as a garlic substitute, molecular analysis revealed only a distant relationship with garlic. We also clarified the previous incorrect classification of cultivated forms within A. ampeloprasum, by showing that leek, kurrat, pearl onion, and bulbous leek should be considered separately from GHG.