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101.
We have found that cover scales on the wing of the butterfly Morpho didius possess specially designed microscopic structures for wavelength-selective reflection and contribute considerably to the brilliant blue colour of the wing. In addition, the cover scale functions as an anisotropic optical diffuser which diffuses light only in one plane, while it makes the range of reflection narrower in the orthogonal plane. The quantitative analyses for the wavelength-selection mechanism and the peculiar optical diffuser are given and the role of such a special optical effect is discussed from physical and biological viewpoints. 相似文献
102.
103.
Hui Z Minamiguchi K Doi H Kinoshita N Kanouchi H Oka T 《In vitro cellular & developmental biology. Animal》2004,40(8-9):293-296
Summary An efficient Escherichia coli expression system for the production of mature-type alkaline serine protease II (mASP II) has been constructed. Complementary
deoxyribonucleic acid-encoding mASP II was inserted into the inducible bacterial expression vector pGE-30. After introduction
into E, coli, the plasmid was expressed by isopropyl-1-thio-β-d-galactopyranoside, and the recombinant product was purified using a Ni-nitrilotriacetic acid column The purified product
had the expected NH2-terminal sequence and showed a scrapie isoform of prion protein-degrading activity using hamster scrapie 263K prions as a
substrate. 相似文献
104.
105.
Temocapril, a angiotensin-converting enzyme (ACE) inhibitor, was tested for neurotrophic activity in primary explant cultures of ventral spinal cord of fetal rats (VSCC). Temocapril had a remarkable effect on neurite outgrowth with a 4.2- to 5.1-fold increased over that of control VSCC at their effective concentrations. In temocapril-treated VSCC, choline acetyltransferase (ChAT) activity was also increased 2.4–3.2 times over that of control at 10–9 and 10–8 M, respectively. Our data suggest that temocapril is a candidate for neurotrophic factors on spinal motor neurons in vitro. A possible therapeutic role for temocapril in damaged motor neurons, such as in motor neuropathy and amyotrophic lateral sclerosis, remains to be defined. 相似文献
106.
Integration of cytochrome b(5) (b5), a tail-anchored protein located in the endoplasmic reticulum (ER) membrane, into the membrane was studied. Mutation of three amino acids, -Leu-Met-Tyr, at the carboxy-terminal end of the transmembrane segment of b5 to alanines resulted in localization of the mutated protein, b5LMY/AAA, in the cytosol as well as in the ER membrane. When an N-glycosylation site was introduced at the carboxy-terminal end of b5LMY/AAA, a substantial amount of the glycosylated form of the mutant protein was recovered in the cytosol fraction. A portion of the mutant protein recovered in the ER was released from the membrane by incubation with the cytosol fraction, but no further release was observed in the second incubation, suggesting that b5 is present in two different states, loosely-bound and firmly-integrated forms, in the ER membrane. These results suggest that b5 is integrated into the ER membrane via the loosely bound state, in which the carboxy-terminal end of the molecule is inserted into the luminal side of the vesicle but is easily translocated back to the cytosol, and that the three amino acids are important for conversion of the loosely-bound state to the firmly-integrated state. 相似文献
107.
Maejima H Kinoshita E Seyama I Yamaoka K 《The Journal of biological chemistry》2003,278(11):9464-9471
Grayanotoxin (GTX) exerts selective effects on voltage-dependent sodium channels by eliminating fast sodium inactivation and causing a hyperpolarizing shift in voltage dependence of channel activation. In this study, we adopted a newly developed protocol that provides independent estimates of the binding and unbinding rate constants of GTX (k(on) and k(off)) to GTX sites on the sodium channel protein, important in the molecular analysis of channel modification. Novel GTX sites were determined in D2S6 (Asn-784) and D3S6 (Ser-1276) by means of site-directed mutagenesis; the results suggested that the GTX receptor consists of the S6 transmembrane segments of four homologous domains facing the ion-conducting pore. We systematically introduced at two sites in D4S6 (Na(v)1.4-Phe-1579 and Na(v)1.4-Tyr-1586) amino acid substituents with residues containing hydrophobic, aromatic, charged, or polar groups. Generally, substitutions at Phe-1579 increased both k(on) and k(off), resulting in no prominent change in dissociation constant (K(d)). It seems that the smaller the molecular size of the residue at Na(v)1.4-Phe-1579, the larger the rates of k(on) and k(off), indicating that this site acts as a gate regulating access of toxin molecules to a receptor site. Substitutions at Tyr-1586 selectively increased k(off) but had virtually no effect on k(on), thus causing a drastic increase in K(d). At position Tyr-1586, a hydrophobic or aromatic amino acid side chain was required to maintain normal sensitivity to GTX. These results suggest that the residue at position Tyr-1586 has a more critical role in mediating GTX binding than the one at position Phe-1579. Here, we propose that the affinity of GTX to Na(v)1.4 sodium channels might be regulated by two residues (Phe and Tyr) at positions Phe-1579 and Tyr-1586, which, respectively, control access and binding of GTX to its receptor. 相似文献
108.
Modulation of aromatase expression in human breast tissue 总被引:4,自引:0,他引:4
109.
Joberty G Perlungher RR Sheffield PJ Kinoshita M Noda M Haystead T Macara IG 《Nature cell biology》2001,3(10):861-866
The Cdc42 GTPase binds to numerous effector proteins that control cell polarity, cytoskeletal remodelling and vesicle transport. In many cases the signalling pathways downstream of these effectors are not known. Here we show that the Cdc42 effectors Borg1 to Borg3 bind to septin GTPases. Endogenous septin Cdc10 and Borg3 proteins can be immunoprecipitated together by an anti-Borg3 antibody. The ectopic expression of Borgs disrupts normal septin organization. Cdc42 negatively regulates this effect and inhibits the binding of Borg3 to septins. Borgs are therefore the first known regulators of mammalian septin organization and provide an unexpected link between the septin and Cdc42 GTPases. 相似文献
110.
Influences of nitrogen sources on usnic acid production in a cultured Mycobiont of the lichen Usnea hirta (L.) Wigg 总被引:1,自引:0,他引:1
Kinoshita Y Yamamoto Y Kurokawa T Yoshimura I 《Bioscience, biotechnology, and biochemistry》2001,65(8):1900-1902
Effects of the nitrogen sources in the medium for the production of secondary metabolites in lichens were examined. The usnic acid production by a mycobiont of the lichen Usnea hirta was higher in the liquid medium containing ammonium and nitrate ions than in those containing amino acids. 相似文献