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2.
Hitoshi Shibata Hideo Ochiai Tetsufumi Kawashima Tadayoshi Okamoto Isamu Inamura 《BBA》1986,852(2-3):175-182
By mixing chlorophyll (Chl) a or b with a dense bovine serum albumin solution, the water-soluble Chl-bovine serum albumin complexes were prepared. These complexes, eluted near the void volume on a gel filtration, were separated well from unreacted bovine serum albumin, indicating an aggregation of such molecules in the complexes. Preparation of chlorophyllide (Chlide) a- or Chlide b-bovine serum albumin complex was unsuccessful, while the phytol-, and β-carotene-bovine serum albumin complexes could be obtained. Chls in the Chl-bovine serum albumin complexes had the following characteristics. (i) Main absorption peak of Chl a or b in the red region occurred at 675 nm or 652 nm, respectively. The Chl a-bovine serum albumin complex having absorption peak at 740 nm was also prepared. As compared with the stabilities of Chl a and b in Triton X-100. (ii) Both Chls in the bovine serum albumin-complexes were stable against oxidative stresses, such as photobleaching, Fenton reagent, peroxidase-H2O2 system. But (iii) they were easily hydrolyzed by chlorophyllase. These properties of Chls in the bovine serum albumin-complexes were similar to those of Chls in the isolated light-harvesting Chl a/b protein complex. A possible localization of Chls within the bovine serum albumin complexes was suggested that the porphyrin moiety of Chl was buried in bovine serum albumin; however, the hydrophilic edge of porphyrin ring, adjacent to the phytol group, occurred in the hydrophilic region of a bovine serum albumin molecule. 相似文献
3.
The surface ornamentation of ascospores ofPreussia globosa was compared in an isolate from paddy soil in Japan and a culture derived from the holotype. The ascospores of two cultures were characterized by the surface ornamentation of a single, semicircular spiral ridge. This new finding strongly suggested that the fungus should be transferred to the genusWesterdykella. Therefore, the morphological and cultural characters of the fungus were re-examined, and the new combinationWesterdykella globosa is herein proposed. 相似文献
4.
In the course of study of fungi from soil, a new genus and species,Stellatospora terricola, was isolated. The fungus is distinguished from other known genera in having star- or comfit-shaped ascospores with a distinct germ pore. The morphological characters of the genus are considered to resemble those of the Sordariaceae in Ascomycotina. 相似文献
5.
Jo Kitawaki Shigeo Inoue Takaya Tamura Takara Yamamoto Hideo Honjo Tadayoshi Higashiyama Yoshio Osawa Hiroji Okada 《The Journal of steroid biochemistry and molecular biology》1993,45(6):485-491
To clarify whether cigarette smoking during pregnancy causes an organic alteration in placental estrogen producing ability, we determined the catalytic activity of aromatase by the tritiated water assay, and tissue level of aromatase cytochrome P-450 (P-450arom) by the specific enzyme-linked immunosorbent assay, in placental samples from nonsmokers and smokers. As pregnancy progressed, both aromatase activity and P-450arom concentration increased in placentas from nonsmokers and smokers. However, the gradient of the increase was significantly less in heavy smokers (20 cigarettes a day) than in normal and moderate smokers (<20 cigarettes a day). At term, the mean aromatase activity and P-450arom concentration in placentas from heavy smokers were significantly lower than in nonsmokers and moderate smokers, while aromatase activity per P-450arom (turnover rate) and the mean placental weight were comparable among the three groups. In contrast, the ratio of aryl hydrocarbon hydroxylase activity to aromatase activity was higher in placentas from heavy smokers. Immunohistochemical studies showed that P-450arom was localized in the cytoplasm of syncytiotrophoblasts of chorionic villi in placentas from both nonsmokers and smokers. These results suggest that the induction of placental P-450arom during gestation is suppressed by maternal smoking, resulting in a reduction in estrogen producing ability, while placental xenobiotic P-450 is induced. 相似文献
6.
Yoshio Osawa Tadayoshi Higashiyama Yukiko Shimizu Carol Yarborough 《The Journal of steroid biochemistry and molecular biology》1993,44(4-6):469-480
Androgen aromatase was found to also be estrogen 2-hydroxylase. The substrate specificity among androgens and estrogens and multiplicity of aromatase reactions were further studied. Through purification of human placental microsomal cytochrome P-450 by monoclonal antibody-based immunoaffinity chromatography and gradient elution on hydroxyapatite, aromatase and estradiol 2-hydroxylase activities were co-purified into a single band cytochrome P-450 with approx. 600-fold increase of both specific activities, while other cytochrome P-450 enzyme activities found in the microsomes were completely eliminated. The purified P-450 showed Mr of 55 kDa, specific heme content of 12.9 ± 2.6 nmol·mg−1 (±SD, N = 4), reconstituted aromatase activity of 111 ± 19 nmol·min−1·mmg−1 and estradiol 2-hydroxylase activity of 5.85 ± 1.23 nmol·min−1·mg−1. We found no evidence for the existence of catechol estrogen synthetase without concomitant aromatase activity. The identity of the P-450 for the two different hormone synthetases was further confirmed by analysis of the two activities in the stable expression system in Chinese hamster ovarian cells transfected with human placental aromatase cDNA, pH β-Aro. Kinetic analysis of estradiol 2-hydroxylation by the purified and reconstituted aromatase P-450 in 0.1 M phosphate buffer (pH 7.6) showed Km of 1.58 μM and Vmax of 8.9 nmol·min−1·mg−1. A significant shift of the optimum pH and Vmax, but not the Km, for placental estrogen 2-hydroxylase was observed between microsomal and purified preparations. Testosterone and androstenedione competitively inhibited estradiol 2-hydroxylation, and estrone and estradiol competitively inhibited aromatization of both testosterone and androstenedione. Estrone and estradiol showed Ki of 4.8 and 7.3 μM, respectively, for testosterone aromatization, and 5.0 and 8.1 μM, respectively, for androstenedione aromatization. Androstenedione and testosterone showed Ki of 0.32 and 0.61 μM, respectively, for estradiol 2-hydroxylation. Our studies showed that aromatase P-450 functions as estrogen 2-hydroxylase as well as androgen 19-, 1β-,and 2β-hydroxylase and aromatase. The results indicate that placental aromatase is responsible for the highly elevated levels of the catechol estrogen and 19-hydroxyandrogen during pregnancy. These results also indicate that the active site structure holds the steroid ssubstrates to face their β-side of the A-ring to the heme, tilted in such a way as to make the 2-position of estrogens and 19-, 1-, and 2-positions of androgens available for monooxygenation. 相似文献
7.
8.
The growth ofTrichoderma lignorum was studied in relation to the carbon balance of the culture system and the respiratory activity at different growth phases. Conidia, after inoculation into the medium, swelled and germinated rapidly. The growth rate of the hyphae at the exponential phase was 0.46 hr−1 (2.2 hr for mass doubling) at 25 C. The yield efficiency of hyphal biomass-C at the cost of glucose-C was 67%, while those of the waste products-C excreted and of CO2-C evolved were, 6.5% and 26.5%, respectively. The yield efficiency of conidia-C to the decrease of hyphae-C was 34%. The germination, growth rate and carbon balance were not affected by different concentrations of glucose from 10 to 2×103 mg glucose-C/l. Carbon dioxide was needed as the growth factor for the initiation of the germination of conidia, but there was no increase in yield efficiency as a result of CO2 fixation. The respiratory rate of the fungus changed drastically as the growth proceeded. The rate of endogenous respiration of conidia was less than 0.2 mg CO2-C/g conidia-C/hr which increased immediately after inoculation into the medium. The highest respiratory rate of hyphae (100–110 mg CO2-C/g hyphae-C/hr) was obtained throughout the exponential phase. Thereafter, decreasing rapidly, the respiratory rate of submerged hyphae of 1-week-old showed only 1.8 mg CO2-C/g biomass-C/hr, whereas the rate of aerial hyphae forming conidia increased again, but did not exceed 10 mg CO2-C/g biomass-C/hr. 相似文献
9.
Watanabe T Saito D Tanabe K Suetsugu R Nakaya Y Nakagawa S Takahashi Y 《Developmental biology》2007,305(2):625-636
The in ovo electroporation technique in chicken embryos has enabled investigators to uncover the functions of numerous developmental genes. In this technique, the ubiquitous promoter, CAGGS (CMV base), has often been used for overexpression experiments. However, if a given gene plays a role in multiple steps of development and if overexpression of this gene causes fatal consequences at the time of electroporation, its roles in later steps of development would be overlooked. Thus, a technique with which expression of an electroporated DNA can be controlled in a stage-specific manner needs to be formulated. Here we show for the first time that the tetracycline-controlled expression method, "tet-on" and "tet-off", works efficiently to regulate gene expression in electroporated chicken embryos. We demonstrate that the onset or termination of expression of an electroporated DNA can be precisely controlled by timing the administration of tetracycline into an egg. Furthermore, with this technique we have revealed previously unknown roles of RhoA, cMeso-1 and Pax2 in early somitogenesis. In particular, cMeso-1 appears to be involved in cell condensation of a newly forming somite by regulating Pax2 and NCAM expression. Thus, the novel molecular technique in chickens proposed in this study provides a useful tool to investigate stage-specific roles of developmental genes. 相似文献
10.
Stable integration and conditional expression of electroporated transgenes in chicken embryos 总被引:2,自引:0,他引:2
Sato Y Kasai T Nakagawa S Tanabe K Watanabe T Kawakami K Takahashi Y 《Developmental biology》2007,305(2):616-624
The in ovo electroporation in chicken embryos has widely been used as a powerful tool to study roles of genes during embryogenesis. However, the conventional electroporation technique fails to retain the expression of transgenes for more than several days because transgenes are not integrated into the genome. To overcome this shortcoming, we have developed a transposon-mediated gene transfer, a novel technique in chicken manipulations. It was previously reported that the transposon Tol2, originally found in medaka fish, facilitates an integration of a transgene into the genome when co-acting with Tol2 transposase. In this study, we co-electroporated a plasmid containing a CAGGS-EGFP cassette cloned in the Tol2 construct along with a transposase-encoding plasmid into early presomitic mesoderm or optic vesicles of chicken embryos. This resulted in persistent expression of EGFP at least until embryonic day 8 (E8) and E12 in somite-derived tissues and developing retina, respectively. The integration of the transgene was confirmed by genomic Southern blotting using chicken cultured cells. We further combined this transposon-mediated gene transfer with the tetracycline-dependent conditional expression system that we also developed recently. With this combined method, expression of a stably integrated transgene could be experimentally induced upon tetracycline administration at relatively late stages such as E6, where a variety of organogenesis are underway. Thus, the techniques proposed in this study provide a novel approach to study the mechanisms of late organogenesis, for which chickens are most suitable model animals. 相似文献