Structural Confirmation of a Unique Carotenoid Lactoside,P457, in Symbiodinium sp. Strain nbrc 104787 Isolated from a Sea Anemone and its Distribution in Dinoflagellates and Various Marine Organisms

The molecular structure of the carotenoid lactoside P457, (3S,5R,6R,3′S,5′R,6′S)‐13′‐cis‐5,6‐epoxy‐3′,5′‐dihydroxy‐3‐(β‐d ‐galactosyl‐(1→4)‐β‐d ‐glucosyl)oxy‐6′,7′‐didehydro‐5,6,7,8,5′,6′‐hexahydro‐β,β‐caroten‐20‐al, was confirmed by spectroscopic methods using Symbiodinium sp. strain NBRC 104787 cells isolated from a sea anemone. Among various algae, cyanobacteria, land plants, and marine invertebrates, the distribution of this unique diglycosyl carotenoid was restricted to free‐living peridinin‐containing dinoflagellates and marine invertebrates that harbor peridinin‐containing zooxanthellae. Neoxanthin appeared to be a common precursor for biosynthesis of peridinin and P457, although neoxanthin was not found in peridinin‐containing dinoflagellates. Fucoxanthin‐containing dinoflagellates did not possess peridinin or P457; green dinoflagellates, which contain chlorophyll a and b, did not contain peridinin, fucoxanthin, or P457; and no unicellular algae containing both peridinin and P457, other than peridinin‐containing dinoflagellates, have been observed. Therefore, the biosynthetic pathways for peridinin and P457 may have been coestablished during the evolution of dinoflagellates after the host heterotrophic eukaryotic microorganism formed a symbiotic association with red alga that does not contain peridinin or P457.     

MOLECULAR PHYLOGENETIC ANALYSIS OF rbcL IN THE PRYMNESIOPHYTA1

The nucleotide sequences of rbcL genes encoding the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined from six species of Prymnesiophyta to clarify their phylogenetic relationships. Molecular phylogenetic trees were constructed using PAUP (Phylogenetic Analysis Using Parsimony). These analyses suggest that the Prymnesiophyta, except for the Pavlovales, area relatively stable monophyletic group. Pleurochrysis carterae, included in the Isochrysidales, is a sister species of a monophyletic group consisting of other members of the Isochrysidales, Gephyrocapsa oceanica and Emiliania huxleyi, members of the Coccosphaerales, Calyptrosphaera sphaeroidea and Umbilicosphaera sibogae var. foliosa, and a member of the Prymnesiales, Chrysochromulina hirta. The nucleotide sequence of rbcL from G. oceanica was identical to that from E. huxleyi within the region examined. Our trees show that G. oceanica and E. huxleyi are more closely related to C. hirta than to U. sibogae, C. sphaeroidea, and P. carterae. These results suggest that orders in the Prymnesiophyceae, including the above-mentioned genera, should be redefined.     

Effect of Japanese sitting style (seiza) on the center of foot pressure after standing

Seiza is one of the most commonly used sitting postures in various enrichment lessons of Japanese origin. It is reported that Seiza with large knee flexion produces harmful effects on the cartilage of knee joints and hemodynamics of the lower legs. This study aimed at examining the influence of Seiza on tissue oxygenation kinetics of the lower limbs, plantar somatic and cutaneous sensation, and the center of foot pressure (COP) sway using 10 young adults. COP sway was measured for 1 min just after sitting on a chair for 10 min (pre-test), after 30-min Seiza (post-test 1), and 5 min after Seiza (post-test 2). To evaluate the COP sway, we used 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3) and high frequency band power spectrum factor (F4). Physiological parameters (i.e., tissue oxygenation kinetics in the lower legs and sensation on the sole) were measured during 30-min Seiza (continuously on tissue oxygenation, and at 1 min intervals on sensation), and for 1 min just before each COP test (pre-test, post-test 1 and 2).Oxygenated hemoglobin/myoglobin (Hb/Mb) concentration decreased markedly and deoxygenated Hb/Mb concentration increased markedly, resulting in reaching a plateau state at around 7 min. Tissue Hb/Mb index changed little during Seiza. Proprioceptive perception thresholds increased rapidly about 17 min after Starting Seiza. Means of 3 COP sway factors of F1, F2 and F4 were significantly higher in post-test 1 than in pre-test and post-test 2. In conclusion, a marked decrease in tissue oxygen concentration of the lower legs within 4-5 min, and an increase of proprioceptive perception thresholds in the sole at about 17 min are induced by Seiza. Although wiggle and quick body sway in the antero-posterior axis increases markedly in an upright posture just after maintaining Seiza for 30 min, sway recovers after sitting on a chair for 5 min.     

Role of inducible nitric oxide synthase in leukocyte extravasation in vivo

Several recent studies have suggested that nitric oxide (NO) derived from the inducible isoform of NO synthase (NOS) may act as an endogenous modulator of the inflammatory response by inhibiting adhesion of leukocytes to endothelial cells in vitro. Few studies have addressed specifically the role of iNOS in regulating leukocyte recruitment in vivo in a model of acute inflammation. Thus, the objective of this study was to assess the role of iNOS in modulating neutrophil (PMN) extravasation in an oyster glycogen-induced model of acute peritonitis in rats. Data obtained in the present study demonstrates that injection (IP) of oyster glycogen induces massive and selective PMN recruitment into the peritoneal cavity of rats at 6 hrs following OG administration. These extravasated cells were found to contain significant amounts of iNOS protein as assessed by Western blot analysis. Treatment of rats with the selective iNOS inhibitor L-iminoethyl-lysine (L-NIL) dramatically reduced NO levels in lavage fluid as measured by decreases in nitrate and nitrite concentrations without significantly affecting iNOS protein levels. Although L-NIL inhibited NO production by >70%, it did not alter oyster glycogen-induced PMN recruitment when compared to vehicle-treated rats. We conclude that PMN-associated, iNOS-derived NO does not play an important role in modulating extravasation of these leukocytes in this model of acute inflammation.     

Effect of Ionic Strength in the Gel Filtration of Charged Polysaccharides

ABSTRACT

Collagen-derived dipeptide prolyl hydroxyproline (Pro-Hyp) is involved in the proliferation and differentiation of various types of cultured cells. To elucidate the mechanism underlying Pro-Hyp actions during osteoblast differentiation, we hypothesized that proteins binding to Pro-Hyp serve to mediate cellular signaling, affecting Runx2 expression. Recently, we performed the characterization of Foxg1, that it enhances Runx2 expression in the presence of Pro-Hyp. Our findings indicate that Pro-Hyp directly binds to the Foxg1 recombinant protein, which leads to the structural alteration of the Foxg1 protein. In addition, Foxg1 appears to interact with Runx2 in the absence of Pro-Hyp, with Pro-Hyp disrupting the interaction between Foxg1 and Runx2. Collectively, our results indicate that the Pro-Hyp bound Foxg1 alters the structured conformation of Foxg1, resulting in conformational changes that lead to dissociation from Runx2. These novel findings suggest that during osteoblast differentiation, Pro-Hyp mediates Runx2 activity though directly binding to Foxg1 and increases Runx2 expression.

Abbreviations: CPT: collagen peptide; GST: Glutathione S-transferase; PAGE: Polyacrylamide gel electrophoresis; PCR: Polymerase chain reaction; prolyl hydroxyproline: Pro-Hyp     

Different protofilament-dependence of the microtubule binding between MAP2 and MAP4

To see a molecular basis of the difference in the microtubule binding between MAP2 and MAP4, we compared the binding of them onto microtubule and Zinc-sheet in the presence of various concentrations of NaCl. The Zinc-sheet is the lateral association of protofilaments arranged in an antiparallel fashion with alternatively exposed opposite surfaces, so that binding requiring adjacent protofilaments is restricted. While the salt-dependence of the MAP2 desorption was not altered between these tubulin polymers, MAP4 dissociated from Zinc-sheet at lower concentrations of NaCl than from microtubule. These results suggest that single protofilament is sufficient for microtubule binding of MAP2 as observed by Al-Bassam et al. [J. Cell Biol. 157 (2002) 1187], but MAP4 appeared to interact with adjacent protofilaments during microtubule-binding. Weakened binding on Zinc-sheets was also observed in the projection domain-deletion mutants of MAP4, so that the difference in the protofilament-dependence would lie in the relatively conserved microtubule-binding domain.     

Novel thyroid hormone receptor antagonists with an N-alkylated diphenylamine skeleton

Thyroid hormones play important roles in growth, development and homeostasis, and disruption of their functions induces serious disease, so novel synthetic thyroid hormone analogues are candidates for clinical application. We designed and synthesized novel diphenylamine derivatives with a thiazolidinedione moiety as the terminal polar group as thyroid hormone receptor (TR) antagonists. Compounds bearing an appropriately sized N-alkyl group showed antagonistic activities towards both the hTRalpha1 and hTRbeta1 subtypes.