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51.
52.
Kazumasa Yamada Shinya Sato Masashi Yamazaki Shinya Yoshikawa Akira Kuwata Mutsuo Ichinomiya 《Phycological Research》2020,68(2):178-182
The small phytoplankton genus Triparma belongs to the class Bolidophyceae and contains two distinct forms: silicified species and naked flagellated species (formerly Bolidomonas). Recent studies showed that four silicified species/strains (Triparma laevis f. inornata, T. laevis f. longispina, T. strigata, and T. aff. verrucosa) belong to a single clade that is paraphyletic, because it also contains an unclassified flagellated strain, and is sister to a flagellated species, T. eleuthera. In this study, we isolated and characterized two new strains of silicified species to test the phylogenetic unity of silicified bolidophytes. The isolates were identified as T. retinervis strains because they possessed fine areolation on the cell wall. 18S rDNA and rbcL phylogenetic analyses demonstrated that T. retinervis formed a new silicified clade that is sister to the flagellated species T. pacifica. This reveals that there are at least two distinct clades including both silicified and flagellated Triparma species. 相似文献
53.
Muneaki Tamura Marni E. Cueno Kazumasa Abe Noriaki Kamio Kuniyasu Ochiai Kenichi Imai 《Cell stress & chaperones》2018,23(6):1337-1343
Candida albicans causes opportunistic fungal infections usually hidden among more dominant bacteria and does not exhibit high pathogenicity in vivo. Among the elderly, due to reduced host resistance to pathogens attributable to immunoscenesence, oral candidiasis is more likely to develop often leading to systemic candidiasis. Surface pre-reacted glass ionomer filler (S-PRG filler) is an ion-releasing functional bioactive glass that can release and recharge six ions which in turn strengthens tooth structure, inhibits demineralization arising from dental caries, and suppresses dental plaque accumulation. However, its effects on C. albicans have never been elucidated. Here, we evaluated the effects of ion released from S-PRG filler on C. albicans. Results show that extraction liquids containing released ions (ELIS) decreased the amount of hydrogen peroxide and catalase activity in C. albicans. Moreover, ELIS presence was found to affect C. albicans: (1) suppression of fungal growth and biofilm formation, (2) prevent adherence to denture base resin, (3) inhibit dimorphism conversion, and (4) hinder the capability to produce secreted aspartyl proteinase. Taken together, our findings suggest that ELIS induces oxidative stress in C. albicans and suppresses its growth and pathogenicity. In this regard, we propose that ELIS has the potential to be clinically used to help prevent the onset and inhibition of oral candidiasis among the elderly population. 相似文献
54.
Manh Huynh Vu Tetsu Ando Shigeo Yoshida Nobutaka Takahashi Sadahiro Tatsuki Kazumasa Katagiri 《Bioscience, biotechnology, and biochemistry》2013,77(7):1615-1617
Ferredoxin-nitrite reductase (EC 1.7.7.1), an enzyme which catalyzes the 6-electron reduction of nitrite to ammonia, has been isolated from Spinacia oleracea. The isolated enzyme was homogeneous by disc electrophoresis with polyacrylamide gel. The molecular weight of the enzyme was estimated to be 86,000 by Ultrogel AcA 34 gel filtration. In the oxidized form, the enzyme had absorption maxima at 278, 388 (Soret band), 573 (α band) and 690 nm, indicating that siroheme is directly involved in the catalysis of nitrite reduction. This absorption spectrum was modified by sulfite, hydroxylamine and cyanide. The enzyme exhibited electron paramagnetic resonance signals with g values of 6.9 and 5.2, which are characteristic of a high spin Fe3+ -siroheme in the molecule. These signals disappeared upon the addition of dithionite or nitrite. This isolated enzyme also contained four moles of labile sulfide and 7 g-atoms of iron per 86,000 g of protein. 相似文献
55.
The effects of changes in host plants on the mate-searching behavior and feeding preferences of the white-spotted longicorn beetle Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae) were examined. All individuals were raised on the same artificial diet until they became pupae. Analysis of the mate-searching behavior of the males showed that many more newly emerged males were attracted to the odor of the artificial diet than to an unbaited control. We prepared three groups of beetles and fed each group on different host plants for one week. The host plants used included the following: an artificial diet (containing Morus alba Linné), Citrus unshiu Marc. branches, and Vaccinium spp. branches. The mate-searching behavior of the males changed in relation to the plant supplied for feeding. Simultaneously, the preference among the three host plants was tested. The newly emerged males preferred the artificial diet. After a week of feeding on one of the three plants, however, the adult males selected and consumed significantly more of the plant that they had just experienced than the other plants. These results suggest that the male mate-location cue can be acquired after adult eclosion. In addition, the male beetles are capable of changing their host-plant preference. If they do so, they use different odor cues for mate location. Newly emerged A. malasiaca females showed no preference for their first choice of food among the three host plants presented, whereas the consumption was significantly larger on C. unshiu branches. After one week of feeding on different host plants, females chose their host plant after the adult stage as well as C. unshiu, but consumed mostly C. unshiu. These results suggest that the food preferences of females are different from those of males. The behavior of females may not be affected by chemical signals from their original host-plant species (as pupae) or from the host-plant species acquired when they emerge as adults. 相似文献
56.
Tomoya Ogawa Motoshi Yasui Masanao Matsui 《Bioscience, biotechnology, and biochemistry》2013,77(8):1445-1447
The Colletotrichum lagenarium PKS1 gene was expressed in the heterologous fungal host, Aspergillus oryzae, under the starch-inducible α-amylase promoter to identify the direct product of polyketide synthase (PKS) encoded by the PKS1 gene. The main compound produced by an A. oryzae transformant was isolated and characterized to be 1,3,6,8-tetrahydroxynaphthalene (T4HN) as its tetraacetate. Since the PKS1 gene was cloned from C. lagenarium to complement the nonmelanizing albino mutant, T4HN was assumed to be an initial biosynthetic intermediate, and thus the product of the PKS reaction, but had not been isolated from the fungus. The production of T4HN by the PKS1 transformant unambiguously identified the gene to encode a PKS of pentaketide T4HN. In addition, tetraketide orsellinic acid and pentaketide isocoumarin were isolated, the latter being derived from a pentaketide monocyclic carboxylic acid, as by-products of the PKS1 PKS reaction. Production of the pentaketide carboxylic acid provided insights into the mechanism for the PKS1 polyketide synthase reaction to form T4HN. 相似文献
57.
Hauser JE Kadekaro AL Kavanagh RJ Wakamatsu K Terzieva S Schwemberger S Babcock G Rao MB Ito S Abdel-Malek ZA 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2006,19(4):303-314
Malignant transformation of melanocytes leads to melanoma, the most fatal form of skin cancer. Ultraviolet radiation (UVR)-induced DNA photoproducts play an important role in melanomagenesis. Cutaneous melanin content represents a major photoprotective mechanism against UVR-induced DNA damage, and generally correlates inversely with the risk of skin cancer, including melanoma. Melanoma risk is also determined by susceptibility genes, one of which is the melanocortin 1 receptor (MC1R) gene. Certain MC1R alleles are strongly associated with melanoma. We hereby present experimental evidence for the role of two melanoma risk factors, constitutive pigmentation, as assessed by total melanin, eumelanin and pheomelanin contents, and MC1R genotype and function, in determining the induction and repair of DNA photoproducts in cultured human melanocytes after irradiation with increasing doses of UVR. We found that total melanin and eumelanin contents (MC and EC) correlated inversely with the extent of UVR-induced growth arrest, apoptosis and induction of cyclobutane pyrimidine dimers (CPD), but not with hydrogen peroxide release in melanocytes expressing functional MC1R. In comparison, melanocytes with loss-of-function MC1R, regardless of their MC or EC, sustained more UVR-induced apoptosis and CPD, and exhibited reduced CPD repair. Therefore, MC, mainly EC, and MC1R function are independent determinants of UVR-induced DNA damage in melanocytes. 相似文献
58.
Tomita Y Yoshikawa M Zhang QW Shimizu I Okano S Iwai T Yasui H Nomoto K 《Journal of immunology (Baltimore, Md. : 1950)》2000,165(1):34-41
A pure method of drug (cyclophosphamide plus busulfan)-induced skin allograft tolerance in mice that can regularly overcome fully H-2-mismatched barriers in mice has been established. The components of the method are i.v. administration of 1 x 108 allogeneic spleen cells on day 0, i.p. injection of 200 mg/kg CP and 25 mg/kg busulfan on day 2, and i.v. injection of T cell-depleted 1 x 107 bone marrow cells from the same donor on day 3. Recipient B10 (H-2b; IE-) mice prepared with this conditioning developed donor-specific tolerance, and long-lasting survival of skin allografts was shown in almost of the recipient mice. In the tolerant B10 mice prepared with new conditioning, stable multilineage mixed chimerism was observed permanently, and IE-reactive Vbeta11+ T cells were reduced in periphery as seen in untreated B10.D2 (H-2d; IE+) mice. The specific tolerant state was confirmed by the specific abrogation against donor Ag in the assays of CTL activity and MLR and donor-specific acceptance in the second skin grafting. These results demonstrated that the limitation of standard protocol of cyclophosphamide-induced tolerance, which have been reported by us since 1984, can be overcome by the additional treatments with the myelosuppressive drug busulfan, followed by 1 x 107 T cell-depleted bone marrow cells. To our knowledge, this is the first report to induce allograft tolerance with a short course of the Ag plus immunosuppressive drug treatment without any kind of mAbs (pure drug-induced tolerance). 相似文献
59.
Masayuki Adachi Masatomo So Kazumasa Sakurai József Kardos Yuji Goto 《The Journal of biological chemistry》2015,290(29):18134-18145
Although amyloid fibrils and amorphous aggregates are two types of aggregates formed by denatured proteins, their relationship currently remains unclear. We used β2-microglobulin (β2m), a protein responsible for dialysis-related amyloidosis, to clarify the mechanism by which proteins form either amyloid fibrils or amorphous aggregates. When ultrasonication was used to accelerate the spontaneous fibrillation of β2m at pH 2.0, the effects observed depended on ultrasonic power; although stronger ultrasonic power effectively accelerated fibrillation, excessively strong ultrasonic power decreased the amount of fibrils formed, as monitored by thioflavin T fluorescence. An analysis of the products formed indicated that excessively strong ultrasonic power generated fibrillar aggregates that retained β-structures but without high efficiency as seeds. On the other hand, when the spontaneous fibrillation of β2m was induced at higher concentrations of NaCl at pH 2.0 with stirring, amorphous aggregates became more dominant than amyloid fibrils. These apparent complexities in fibrillation were explained comprehensively by a competitive mechanism in which supersaturation-limited reactions competed with supersaturation-unlimited reactions. We link the kinetics of protein aggregation and a conformational phase diagram, in which supersaturation played important roles. 相似文献
60.
Eshima N Tokumaru O Hara S Bacal K Korematsu S Tabata M Karukaya S Yasui Y Okabe N Matsuishi T 《PloS one》2011,6(4):e19409