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Articles by N Sato
Total Records ( 5 ) for N Sato
  N Sato , S Awata and H. Munehara
 

Sato, N., Awata, S., and Munehara, H. 2009. Seasonal occurrence and sexual maturation of Japanese pygmy squid (Idiosepius paradoxus) at the northern limits of their distribution. – ICES Journal of Marine Science, 66: 811–815.

The distribution of aquatic animals is limited by water temperature. However, little is known about migration patterns, overwintering, and reproduction at the extremities of their distribution. To investigate the sexual maturation of Japanese pygmy squid (Idiosepius paradoxus) and their ability to survive during winter at the northern limits of their distribution, we collected samples monthly at Usujiri in northern Japan and carried out experiments on low-temperature tolerance. Squid were collected during 4 months in autumn and early winter. In autumn, all squid were large and sexually mature, and many egg masses were found on the surface of seagrass, whereas in early winter, only small immature squid were collected. A warm north-flowing current reached the Usujiri area during autumn, so the squid were likely transported by the current and some of the small squid were recruits that hatched there. Field data and the results of experiments on tolerance of the species to low temperatures showed that it cannot survive at the low temperatures around Usujiri in winter. The migration pattern of I. paradoxus may differ from the traditional pattern for marine resources, where young fish are transported passively and do not reproduce at the extremities of their distribution.

  N Sato , Y Ito , A Ioka , M Tanaka and H. Tsukuma
 

Relative 5-year survival for stomach cancer has increased gradually in Osaka for more than two decades, while women show a small but consistently lower survival for it. We analyzed gender differences in stomach cancer survival, using relative survival model proposed by Dickman et al. Study subjects were reported stomach cancer cases diagnosed in 1975–99. We estimated the excess hazard ratios (EHRs) of death using Poisson's regression model. The crude EHR for women was 1.12 [95% confidence interval (CI): 1.09–1.14] in comparison with men. After adjustments for year and age at diagnosis, the EHR for women decreased to 1.07 (95% CI: 1.05–1.09), and furthermore, it reached to an insignificant level of 1.02 (95% CI: 0.99–1.04) after an additional adjustment for the extent of disease (localized, regional, distant and unknown). With further adjustments by histological type (intestinal, diffuse and others/unknown), method of detection (screening or not) and treatment (surgery or not), the EHR decreased to 0.97 (95% CI: 0.94–0.99), significantly lower than the unity. These results indicate that the lower stomach cancer survival among women was attributable mainly to more advanced stages among women. The survival for women would have been a little better than for men if prognostic factors for stomach cancer had been comparable between the sexes. Inequality by the gender in taking screening, medical examination or treatment for stomach cancer was suggested to exist in Osaka, Japan.

  M. T Fujiwara , K Sekine , Y. Y Yamamoto , T Abe , N Sato and R. D. Itoh
 

Chloroplast division involves the tubulin-related GTPase FtsZ that assembles into a ring structure (Z-ring) at the mid-chloroplast division site, which is where invagination and constriction of the envelope membranes occur. Z-ring assembly is usually confined to the mid-chloroplast site by a well balanced counteraction of the stromal proteins MinD and MinE. The in vivo mechanisms by which FtsZ nucleates at specific sites, polymerises into a protofil-ament and organises a closed ring of filament bundles remain largely unknown. To clarify the dynamic aspects of FtsZ, we developed a living cell system for simultaneous visualisation of various FtsZ configurations, utilising the Arabidopsis thaliana overexpressor and mutant of the MinE (AtMinE1) gene, which were modified to weakly express green fluorescent protein (GFP) fused to AtFtsZ1-1. Time-lapse observation in the chloroplasts of both plants revealed disorderly movement of the dots and short filaments of FtsZ. The short filaments often appeared to emanate from the dots and to converge with a long filament, producing a thick cable. In the AtMinE1 overexpressor, we also observed spirals along the longitudinal axis of the organelle that often rolled the closed rings together. In the atminE1 mutant, we visualised the ‘isolated’ rings with a maximum diameter of ~2 µm that did not encircle the organelle periphery, but appeared to be suspended in the stroma. Our observations further demonstrated heterogeneity in chloroplast shapes and concurrently altered configurations of FtsZ in the mutant.

  K Shimamura , H Takahashi , H Kitazawa , Y Miyamoto , A Nagumo , C Tang , D Dean , T Nagase , N Sato and S. Tokita
 

ELOVL6, a member of the elongation of very long-chain fatty acids (ELOVL) family, has recently been identified as the rate-limiting enzyme for the elongation of palmitoyl-CoA. ELOVL6 deficient mice are protected from high-fat diet induced insulin resistance, suggesting that ELOVL6 might be a promising target for the treatment of metabolic disorders. Despite the increasing interest in Elovl6 as a therapeutic target, the lack of chemical tools for this enzyme has limited further elucidation of the biochemical and pharmacological properties of ELOVL6. We have identified Compound-A, a potent inhibitor for ELOVL6, by screening our company library and subsequently optimizing hit compounds. Compound-A potently inhibited human and mouse ELOVL6 and displayed >100-fold greater selectivity for ELOVL6 over other ELOVL family members. Consistent with its potent and selective inhibitory activity toward ELOVL6, [3H]Compound-A bound to ELOVL6 with high affinity while showing no specific binding to other ELOVL enzymes. The observation that [3H]Compound-A bound to ELOVL6 in a palmitoyl-CoA-dependent manner in the absence of malonyl-CoA and NADPH suggests that Compound-A might recognize an enzyme–substrate complex, e.g. an acyl–enzyme intermediate. Collectively, these observations demonstrate that Compound-A and its tritiated form are useful tools for biochemical and pharmacological characterization of ELOVL6.

 
 
 
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