凝溶蛋白对骨骼肌天然细肌丝的作用

凝溶蛋白是Ｆ－肌动蛋白丝的钙依赖性切割性蛋白质．经过焦磷酸溶液选择性抽提和微酸性介质的有效分离,可以得到纯度较高的天然细肌丝．在Ｃａ２＋存在时,凝溶蛋白可以切割天然细肌丝．但是,凝溶蛋白对天然细肌丝的作用时程与其对Ｆ－肌动蛋白丝的作用有着显著差异,提示细肌丝中的非肌动蛋白蛋白质可能影响了凝溶蛋白对天然细肌丝的结合或者切割速率．     

Influences of Immunosuppressive Agents,FK506 and Cyclosporin on Systemic Candida albicans Infection in Mice

The effects of the immunosuppressive agents FK506 (tacrolimus) and cyclosporin (CyA) on Candida albicans infection in mice were compared with those of cyclophosphamide. FK506 and CyA did not exacerbate C. albicans infection in mice when the effects were determined on the basis of survival ratio and colony forming units (CFU) in the kidney, although cyclophosphamide (CY) impaired the host defence mechanisms of mice against C. albicans infection. The effects of FK506 and CyA on the body weight of mice, histopathological changes of lymphoid tissues and formation of granulomas in kidney were also studied in comparison with those of CY. This revised version was published online in June 2006 with corrections to the Cover Date.     

Construction of protocellular structures under simulated primitive earth conditions

We have developed experimental approaches for the construction of protocellular structures under simulated primitive earth conditions and studied their formation and characteristics. Three types of envelopes; protein envelopes, lipid envelopes, and lipid-protein envelopes are considered as candidates for protocellular structures. Simple protein envelopes and lipid envelopes are presumed to have originated at an early stage of chemical evolution, interaction mutually and then evolved into more complex envelopes composed of both lipids and proteins.Three kinds of protein envelopes were constructedin situ from amino acids under simulated primitive earth conditions such as a fresh water tide pool, a warm sea, and a submarine hydrothermal vent. One protein envelope was formed from a mixture of amino acid amides at 80 °C using multiple hydration-dehydration cycles. Marigranules, protein envelope structures, were produced from mixtures of glycine and acidic, basic and aromatic amino acids at 105 °C in a modified sea medium enriched with essential transition elements. Thermostable microspheres were also formed from a mixture of glycine, alanine, valine, and aspartic acid at 250 °C and above. The microspheres did not form at lower temperatures and consist of silicates and peptide-like polymers containing imide bonds and amino acid residues enriched in valine. Amphiphilic proteins with molecular weights of 2000 were necessary for the formation of the protein envelopes.Stable lipid envelopes were formed from different dialkyl phospholipids and fatty acids.Large, stable, lipid-protein envelopes were formed from egg lecithin and the solubilized marigranules. Polycations such as polylysine and polyhistidine, or basic proteins such as lysozyme and cytochromec also stabilized lipid-protein envelopes.     

Effects of hypergravity environment of the ultrastructure of the golden hamster parathyroid gland

The fine structure of the parathyroid glands of golden hamsters exposed to 2, 5 or 10 g environment for 5 h was studied. In the centrifuged hamsters, many secretory granules are located in a peripheral position just beneath the plasma membrane of chief cells, and the Golgi complexes and cisternae of the granular endoplasmic reticulum are significantly increased compared with those of control animals. There are no significant differences between the control and centrifuged animals with regard to secretory granules, large secretory granules, lysosomes, vacuolar bodies and lipid droplets. These findings suggest that the secretory activity of the parathyroid gland may be stimulated in response to hypergravity environment.     

Pigment types in sheep, goats, and llamas

Pigment types in various colors of fiber from sheep, goats, and llamas were assayed by a method using high performance liquid chromatography. In these three species the black/gray group is due to eumelanin, which is fully intense in all three species. Red phenotypes are due to pheomelanin and fade considerably with age in fiber from sheep and goats, but not in llamas. This phenomenon has implications on the genetic mechanisms used in generating white fiber. Brown phenotypes in sheep are due to eumelanin, in goats these phenotypes are equivocal, and they were not observed in llamas.     

Tyrosinase‐catalyzed oxidation of resveratrol produces a highly reactive ortho‐quinone: Implications for melanocyte toxicity

trans‐Resveratrol (3,5,4′‐trihydroxy‐trans‐stilbene, RES), a naturally occurring polyphenol, has recently attracted increased interest as a health‐beneficial agent. However, based on its p‐substituted phenol structure, RES is expected to be a substrate for tyrosinase and to produce a toxic o‐quinone metabolite. The results of this study demonstrate that the oxidation of RES by tyrosinase produces 4‐(3′,5′‐dihydroxy‐trans‐styrenyl)‐1,2‐benzoquinone (RES‐quinone), which decays rapidly to an oligomeric product (RES‐oligomer). RES‐quinone was identified after reduction to its corresponding catechol, known as piceatannol. RES‐quinone reacts with N‐acetylcysteine, a small thiol, to form a diadduct and a triadduct, which were identified by NMR and MS analyses. The production of a triadduct is not common for o‐quinones, suggesting a high reactivity of RES‐quinone. RES‐quinone also binds to bovine serum albumin through its cysteine residue. RES‐oligomer can oxidize GSH to GSSG, indicating its pro‐oxidant activity. These results suggest that RES could be cytotoxic to melanocytes due to the binding of RES‐quinone to thiol proteins.     

Antibodies against a nonapeptide of polyomavirus middle T antigen: cross-reaction with a cellular protein(s).

Antibodies were raised against the sequence Glu-Glu-Glu-Glu-Tyr-Met-Pro-Met -Glu, which represents a part of the middle T antigen of polyomavirus that is considered to be important in inducing the phenotype of transformed cells. The antibodies reacted with native as well as denatured middle T antigens. In addition, the antibodies immunoprecipitated a cellular protein with an apparent molecular weight of 130,000 (130K) from mouse and rat cells. In some cases, a 33K protein was also immunoprecipitated. Immunoprecipitation of middle T antigen as well as 130K and 33K proteins was blocked by the peptide. The antibodies labeled microfilaments of untransformed mouse, rat, human, and chicken cells by immunofluorescence. This labeling was also blocked by the peptide. The labeling pattern and distribution under a variety of conditions were indistinguishable from those of anti-actin antibodies, although no evidence has been obtained to indicate that the anti-peptide antibodies react with actin. The 130K protein migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis slightly slower than chicken gizzard vinculin (130K) and slightly faster than myosin light-chain kinase of chicken smooth muscle (130K). Neither of these proteins absorbed the anti-peptide antibodies. The 33K protein does not seem to be tropomyosin (32K to 40K).     

OsRALyase1, a putative F-box protein identified in rice,Oryza sativa,with enzyme activity identical to that of wheat RALyase

A rice gene, OsRALyase1, encoding a product similar to wheat ribosomal RNA apurinic site specific lyase (RALyase), was isolated and expressed in vitro. An open reading frame of the gene predicted a protein of 476 amino acid residues with 75% identity to RALyase and contained an F-box-like motif in its amino terminal region. The rice gene product expressed in a wheat-germ protein expression system had the same characteristics as its wheat counterpart, cleaving a specific depurinated site of the 28S rRNA sarcin-ricin domain.     

Occurrence of D-rhamnan as the common antigen reactive against monoclonal antibody E87 in Pseudomonas aeruginosa IFO 3080 and other strains.

S. Sawada and co-workers reported that a monoclonal antibody (MAb), E87, interacted with about 80% of Pseudomonas aeruginosa isolates, and they separated a rhamnose-rich polysaccharide as the probable antigen for MAb E87 from P. aeruginosa IFO 3080 (S. Sawada, T. Kawamura, Y. Masuho, and K. Tomibe, J. Infec. Dis. 152:1290-1299, 1985). In the present study, the rhamnose-rich polysaccharide was shown to be structurally and immunologically identical to the D-rhamnan of P. aeruginosa IID 1008 (S. Yokota, S. Kaya, S. Sawada, T. Kawamura, Y. Araki, and E. Ito, Eur. J. Biochem. 167:203-209, 1987). Furthermore, a set of enzymes responsible for the formation of GDP-rhamnose (probably in a D-form) from GDP-D-mannose was found in the 100,000 x g supernatant fractions obtained from all of nine P. aeruginosa strains reactive against MAb E87. The result strongly supports a possibility that lipopolysaccharides having a D-rhamnan chain widely occur as the common antigen among various P. aeruginosa isolates.