Bacteriocin Release Protein Triggers Dimerization of Outer Membrane Phospholipase A In Vivo

Bacteriocin release protein is known to activate outer membrane phospholipase A (OMPLA), which results in the release of colicin from Escherichia coli. In vivo chemical cross-linking experiments revealed that the activation coincides with dimerization of OMPLA. Permeabilization of the cell envelope and dimerization were characterized by a lag time of 2 h.     

Study of enteric pathogens among children in the tropics and effects of prolonged storage of stool samples

The study was performed to compare real-time PCR after nucleic acid extraction directly from stool samples as well as from samples stored and transported on Whatman papers or flocked swabs at ambient temperature in the tropics. In addition, the possible suitability for a clear determination of likely aetiological relevance of PCR-based pathogen detections based on cycle threshold (Ct) values was assessed. From 632 Tanzanian children <5 years of age with and without gastrointestinal symptoms, 466 samples were subjected to nucleic acid extraction and real-time PCR for gastrointestinal viral, bacterial and protozoan pathogens. Equal or even higher frequencies of pathogen detections from Whatman papers or flocked swabs were achieved compared with nucleic acid extraction directly from stool samples. Comparison of the Ct values showed no significant difference according to the nucleic acid extraction strategy. Also, the Ct values did not allow a decision whether a detected pathogen was associated with gastrointestinal symptoms.     

Opposite Contributions of Trunk and Leg Fat Mass with Plasma Lipase Activities: The Hoorn Study

Objective: Lipoprotein lipase (LPL) and hepatic lipase (HL) are essential in hydrolysis of triglyceride‐rich lipoproteins. LPL activity is negatively, whereas HL activity is positively, associated with total body fat. We determined the associations of trunk and leg fat mass with plasma LPL and HL activities in a cross‐sectional study. Research Methods and Procedures: LPL and HL activities were determined in post‐heparin plasma in a sample of 197 men and 209 women, 60 to 87 years of age. A total body DXA scan was performed to determine trunk and leg fat mass. Results: In women, but not in men, trunk fat mass was negatively associated with LPL activity, whereas leg fat mass was positively associated, after mutual adjustment and adjustment for age. Standardized βs (95% confidence interval) for trunk and leg fat mass were ?0.24 (?0.41; ?0.08) and 0.14 (?0.02; 0.31), respectively (interaction by sex, p = 0.03). Larger trunk fat mass was associated with higher HL activity in men [0.48 (0.28; 0.68)] and women [0.40 (0.24; 0.56)]. A negative association of leg fat mass and HL activity was observed in men, although not statistically significant [?0.13 (?0.33; 0.06)], and in women [?0.28 (?0.38; ?0.18)]. Discussion: Abdominal fat is associated with unfavorable and femoral fat with favorable LPL and HL activities in plasma.     

Purification and characterization of endonucleases DraII and III from Deinococcus radiophilus

Deinococcus radiophilus strain ATCC 27603 contains, apart from endonuclease DraI [1], two additional sequence-specific endonucleases. These enzymes, designated DraII and DraIII, recognize nucleotide sequences with novel specificities, PuG↓GNCCPy and CACNN↓GTG, respectively.     

Occurrence of benign glandular tissue in orbital aspirates. Importance of recognizing its lacrimal gland origin

In the course of performing approximately 100 orbital aspirates, glandular epithelial inclusions were seen in three specimens from three patients. These inclusions, now recognized as benign and normal structures, initially led to false-positive cytologic results in two of the three cases. On the basis of reconstructing the clinical events, they appear to have been derived from the minor lacrimal glands in two cases and from the major lacrimal glands in the third. The potential hazard of regarding these glandular inclusions as indicating metastatic neoplasm is emphasized.     

Subcellular fractionation of striatum: Sedimentation properties of dopaminergic synaptosomes

Linear sucrose density gradient centrifugation of a crude synaptosomal-mitochondrial preparation of rat striatum was performed at 82, 500g for 7.5, 15 and 30 min and 1, 4 and 20 h. After centrifugation various marker enzyme activities were measured throughout the gradients, viz. tyrosine hydroxylase (TH) and DOPA decarboxylase (DD) as markers of dopaminergic synaptosomes, lactate dehydrogenase (LDH) as a general synaptosomal marker and monoamine oxidase (MAO) as a mitochondrial marker. At all centrifugation times the distribution patterns of TH and DD activity coincided almost perfectly. Notable differences were found between the sedimentation properties of these TH/DD-containing particles and LDH-containing particles: TH and DD were symmetrically distributed in the gradient much sooner than LDH, at all centrifugation times the top of the TH and DD curves was lying deeper in the gradient than the highest LDH activity, and Th and DD became enriched in the gradients to a much greater extent than LDH. It is concluded that rat striatal dopaminergic synaptosomes form a relatively homogenous population of particles sedimenting faster into the gradients than the bulk of striatal synaptosomes does. This distinct sedimentation behaviour of the dopaminergic synaptosomes can be usefully applied for analytical purposes.     

A Mechanism of Energy Dissipation in Cyanobacteria

When grown under a variety of stress conditions, cyanobacteria express the isiA gene, which encodes the IsiA pigment-protein complex. Overexpression of the isiA gene under iron-depletion stress conditions leads to the formation of large IsiA aggregates, which display remarkably short fluorescence lifetimes and thus a strong capacity to dissipate energy. In this work we investigate the underlying molecular mechanism responsible for chlorophyll fluorescence quenching. Femtosecond transient absorption spectroscopy allowed us to follow the process of energy dissipation in real time. The light energy harvested by chlorophyll pigments migrated within the system and eventually reaches a quenching site where the energy is transferred to a carotenoid-excited state, which dissipates it by decaying to the ground state. We compare these findings with those obtained for the main light-harvesting complex in green plants (light-harvesting complex II) and artificial light-harvesting antennas, and conclude that all of these systems show the same mechanism of energy dissipation, i.e., one or more carotenoids act as energy dissipators by accepting energy via low-lying singlet-excited S₁ states and dissipating it as heat.     

Heptameric association of light-harvesting complex II trimers in partially solubilized photosystem II membranes.

We report a structural characterization by electron microscopy and image analysis of a supramolecular complex consisting of seven trimeric light-harvesting complex II proteins. The complex was readily observed in partially-solubilized Tris-washed photosystem II membranes from spinach but was also found to occur, with a low frequency, in oxygen-evolving photosystem II membranes. The structure reveals six peripheral trimers with the same rotational orientation and a central trimer with the opposite orientation. We conclude that the heptamer represents a naturally occurring aggregation state of part of the light-harvesting complex II trimers in the thylakoid membranes.     

Amino acid sequence of the nonsecretory ribonuclease of human urine

The amino acid sequence of a nonsecretory ribonuclease isolated from human urine was determined except for the identity of the residue at position 7. Sequence information indicates that the ribonucleases of human liver and spleen and an eosinophil-derived neurotoxin are identical or very closely related gene products. The sequence is identical at about 30% of the amino acid positions with those of all of the secreted mammalian ribonucleases for which information is available. Identical residues include active-site residues histidine-12, histidine-119, and lysine-41, other residues known to be important for substrate binding and catalytic activity, and all eight half-cystine residues common to these enzymes. Major differences include a deletion of six residues in the (so-called) S-peptide loop, insertions of two, and nine residues, respectively, in three other external loops of the molecule, and an addition of three residues at the amino terminus. The sequence shows the human nonsecretory ribonuclease to belong to the same ribonuclease superfamily as the mammalian secretory ribonucleases, turtle pancreatic ribonuclease, and human angiogenin. Sequence data suggest that a gene duplication occurred in an ancient vertebrate ancestor; one branch led to the nonsecretory ribonuclease, while the other branch led to a second duplication, with one line leading to the secretory ribonucleases (in mammals) and the second line leading to pancreatic ribonuclease in turtle and an angiogenic factor in mammals (human angiogenin). The nonsecretory ribonuclease has five short carbohydrate chains attached via asparagine residues at the surface of the molecule; these chains may have been shortened by exoglycosidase action.(ABSTRACT TRUNCATED AT 250 WORDS)