Antibacterial and Inducer Activities for Tetracycline Resistance by Its Derivatives and Analogues

Antibacterial and inducer activities of thirteen TC derivatives were investigated for tetracycline (TC) resistance in staphylococcus aureus. Four compounds of the TC derivatives were not able to induce the resistance to TC in Staphylococcus aureus MS3937 r_ms7 (TC)⁺ harboring an inducible TC resistance determinant located on a plasmid. The 12a-hydroxy position seems to be essential for the inducer activity.     

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis: 2. Genetic polymorphism of lymphocyte cytosol 64K polypeptide

Summary We describe a genetic polymorphism of human lymphocyte cytosol major polypeptide with mol. wt. 64,000, detected in peripheral blood lymphocytes by high resolution two-dimensional electrophoresis. Three different electrophoretic types (1-1, 2-1, 2-2) of the polypeptide have been identified. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The polypeptide occurs in the cytosol and is predominent in peripheral blood lymphocytes, B-lymphoblastoid cells, T-lymphoblastoid cells, lymph node, and spleen. The polypeptide has not been detected in HeLa cells, fibroblasts, erythrocytes, serum, and cerebrum. Traces of the polypeptide exist in liver, kidney, and skeletal muscle. It is proposed that the polypeptide and its locus be temporarily designated lymphocyte cytosol 64K polypeptide (LC64K polypeptide) andLC64P, respectively. In a Japanese population, the gene frequencies ofLC64P ¹ andLC64P ² were 0.936 and 0.064, respectively. The data suggest thatLC64P is a new locus, product of which shows genetic polymorphism and is associated with the function and/or the structure of lymphocytes.     

Studies on the visual acuity of sheep using shape discrimination learning

Two experiments were conducted to determine the visual acuity of sheep. Three ewes were trained to discriminate between a Landolt ring and an ordinary ring of equal size associated with feed. The left and right positions of the 2 targets were shifted according to the Gellermann series. After the ewes were fully trained, their visual acuity was determined by changing the size of the rings or the distance from the target. The ewes were subjected daily to 1 or 2 sessions which consisted of 30 trials each. The criterion of successful discrimination was 2 (Exp. I) or 3 (Exp. II) consecutive sessions with more than 21 correct choices (P<0.05, Chi-square test). The best scores of visual acuity in the 3 ewes were 0.085, 0.095 and 0.19, respectively.     

High-resolution crystal structure of peptidyl-tRNA hydrolase from Thermus thermophilus

Peptidyl-tRNA hydrolase (Pth) cleaves the ester bond between the peptide and the tRNA of peptidyl-tRNA molecules, which are the products of defective translation, to recycle the tRNA for further rounds of protein synthesis. Pth is ubiquitous in nature, and its activity is essential for bacterial viability. Here, we have determined the crystal structure of Pth from Thermus thermophilus (TtPth) at 1.00 Å resolution. This is the first structure of a Pth from a thermophilic bacterium and the highest resolution Pth structure reported so far. The present atomic resolution data enabled the calculation of anisotropic displacement parameters for all atoms, which revealed the directionality of the fluctuations of key regions for the substrate recognition. Comparisons between TtPth and mesophilic bacterial Pths revealed that their structures are similar overall. However, the structures of the N- and C-terminal, loop-helix α4, and helix α6 regions are different. In addition, the helix α1 to strand β4 region of TtPth is remarkably different from those of the mesophilic bacterial Pths, because this region is 9 or 10 amino acid residues shorter than those of the mesophilic bacterial Pths. This shortening seems to contribute to the thermostability of TtPth. To further understand the determinants for the thermostability of TtPth, we compared various structural factors of TtPth with those of mesophilic bacterial Pths. The data suggest that the decreases in accessible surface area and thermolabile amino acid residues, and the increases in ion pairs, hydrogen bonds, and proline residues cooperatively contribute to the thermostability of TtPth.     

Conformation and properties of hammerhead-type RNA enzymes

We designed a hammerhead-type RNA enzyme system which consists of three ribooligonucleotide strands (1-3), synthesized these oligomers and their analogues, and examined conformation and properties of the RNA complexes. Imino proton NMR spectra of the complexes were measured and the signals were assigned by comparison with the spectra of some model duplexes. Examination of a complex containing a G----I mutation (Y = I) revealed that the 2-amino group of the third guanosine residue in the loop 1 (L1) plays an important role for maintaining both the activity and loop conformation.     

Vascular endothelial growth factor in patients with high-altitude pulmonary edema.

To examine the role of VEGF in the pathogenesis of high-altitude pulmonary edema (HAPE), we measured the concentrations of VEGF in venous serum and bronchoalveolar lavage fluid in patients with HAPE and in healthy volunteers. The VEGF in venous serum of the patients was normal at admission and significantly increased at recovery. Similarly, the VEGF in bronchoalveolar lavage fluid of the patients was increased at recovery compared with admission, but values at both admission and recovery were significantly lower than those of the controls. The present finding suggests that VEGF probably is destroyed in the lung of HAPE, and it appears less likely to have a critical part in the pathogenesis of HAPE but has rather an important role in the repair process for the impaired cell layer.     

Sodium localization in the choroid plexus

Summary The localization of sodium ion in the cat choroid plexus was studied by use of potassium pyroantimonate. The precipitates formed by the potassium pyroantimonate occur mostly on the plasma membrane in the epithelial cell and occasionally in the perivascular space. The precipitates in the epithelial cell are most numerous at the apical surface, particularly on the microvilli, and least in number at the basal and lateral surfaces. In the endothelial cell, the dense precipitates are situated on the plasma membrane as well as on the limiting membrane of the pinocytotic vesicle. Although the dense precipitates are sometimes situated on the external surface of the plasma membrane of the epithelial cell, most of them are localized on the internal surface of the plasma membrane. A similar localization of the precipitates is to be seen on the plasma membrane of the erythrocyte. When the cerebrospinal fluid/plasma ion ratio and potential gradients across the choroid plexus are considered, the precipitates on the plasma membrane would suggest a localization of sodium needed for the activation of ATPase.

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Zusammenfassung Die Lokalisation des Natriumions im Plexus chorioideus der Katze wurde mit Hilfe von Kaliumpyroantimonat untersucht. Die durch Kaliumpyroantimonat gebildeten Niederschläge treten meistens an der Plasmamembran in den Epithelzellen und gelegentlich im perivaskulären Raum auf. In den Epithelzellen kommen die Niederschläge am zahlreichsten an der apikalen Oberfläche vor, besonders an den Mikrovilli, am geringsten an den basalen und lateralen Oberflächen. In der Endothelzelle liegen die dichten Niederschläge an der Plasmamembran und an der Grenzmembran der Pinozytosebläschen. Einige der dichten Niederschläge befinden sich an der äußeren Oberfläche der Plasmamembran der Epithelzellen, die meisten aber an der inneren Oberfläche der Plasmamembran. Eine ähnliche Lokalisation der Niedersschläge wurde an der Plasmamembran des Erythrozyten festgestellt. Wenn man das Liquor Plasma-Ionenverhältnis und die Potentialgradienten am Plexus chorioideus in Betracht zieht, liegt es nahe, die nachgewiesene Lokalisation des Natriums auf eine Aktivierung von ATPase zu beziehen.

     

Polysaccharides of the cellular slime mold II. Change of intra- and extracellular polysaccharides during growth phase of Dictyostelium discoideum NC-4

The three intra- and extracellular polysaccharide fractions were isolated during the growth phase of Dictyostelium discoideum NC-4, and the change in content of component sugars of four fractions during the culture period was examined. Myxamoebae most extensively contain a polysaccharide fraction extracted with phenol-water (polysaccharide fraction I) in a quantity of about 15–23% per dry cell. After 15 h the uronic acid formed in the polysaccharide fraction I, and the cell, could be aggregated. The glucosamine content in the polysaccharide fraction I reached a maximum as the myxamoebae entered the exponential phase, and a large amount of galactose was produced as the cell entered the stationary phase. The phenol-water extract from the cells of the stationary phase was reacted with concanavalin-A.     

Comparison of R- and S-form lipopolysaccharides fractionated from Escherichia coli UKT-B lipopolysaccharide in pyrogen and Limulus tests

Different LPS was shown to have a relatively different proportion of O-specific chain-less (R-form) LPS by polyacrylamide gel electrophoresis (PAGE) with sodium deoxycholate (DOC). By using DOC-PAGE, S-form LPS having O-chain with approximately 11 repeating units on average (S-Fr) and O-chain-less LPS (R-Fr) were separated from Escherichia coli UKT-B S-form LPS. Significantly stronger pyrogenicity was observed in R-Fr than in S-Fr when measured on the weight basis. Similar result was observed in Limulus test. Comparing biological activities of different S-form LPS, attention should be given to the amounts of co-existing R-form LPS.