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91.
A particulate fraction prepared from Mycobacterium phlei grown in a metal-deficient medium exhibited a greatly reduced activity of stearoyl-CoA desaturase compared to that from normally grown cells. Metal deficiency, however, had no effect on the FAD-dependent NADPH-cytochrome C reductase activity, which has been suggested to participate in the desaturation process. When the cells were grown in the deficient medium supplemented with both Fe2+ and Mg2+, the desaturase activity was restored to the normal level. Supplementation with Mg2+ alone promoted growth but did not restore the desaturase activity, whereas Fe2+ alone did cause a significant restoration. Among the various metal ions tested, only Fe2+ and Fe3+ enhanced the formation of desaturase activity in the deficient medium. When added to the assay medium in vitro, Fe2+ and Fe3+ did not stimulate the desaturase activity of the particulate fraction from the deficient cells. Cultivation in the metal-deficient medium had essentially no effect on the levels of cytochromes in the particulate fraction, but dramatically decreased the non-heme iron content and the amount of a high-spin ferric species exhibiting an ESR signal at g=4.3. No labile sulfur could be detected in the normal or metal-deficient particulate fractions. It is concluded that the presence of iron ions in the culture medium is necessary for the synthesis and/or assembly of the terminal portion of the desaturase system. 相似文献
92.
Methods were developed for the radioisotopic assay of argininosuccinate synthetase [L-citrulline: L-aspartate ligase (AMP-forming), EC 6.3.4.5] and argininosuccinase [L-argininosuccinate arginine-lyase, EC 4.3.2.1]. The assay of argininosuccinate synthetase was based on the separation of [14C]argininosuccinate formed from aspartate and [carbamoyl-14C]citrulline in the presence of ATP from the substrate citrulline. For this, the product was converted to its anhydride form by boiling for 30 min at pH 2.0 followed by application on a column of Dowex 50W (pyridine form). Argininosuccinic anhydride was eluted with 0.3 M pyridine acetate buffer, pH 4.25, while citrulline was eluted with 0.1 M pyridine acetate buffer, pH 3.80. The assay of argininosuccinase was based on the separation of [14C]argininosuccinic acid formed from arginine and [U-14C]fumaric acid from the substrate fumarate on a column of Dowex 50W(H+ form). The argininosuccinic acid was adsorbed on the column and eluted with 1 M pyridine solution, while fumarate was not adsorbed. The distributions of these two enzymes in various organs and cell fractions were reinvestigated using these methods. 相似文献
93.
Mycobacterium smegmatis cells incorporated [1-14C]oleic acid into triacylglycerols (TG) from the medium more rapidly than shorter chain fatty acids, caprilic and butyric acids. This incorporation was inhibited more strongly by 10(-3) M N-ethylmaleimide than by 10(-3) M KCN. [14C]TG in the bacterial cells was utilized when the cells were in poor nutritional conditions, such as phosphate buffer (pH 7.0) containing oleic acid. Accumulation of TG was observed in the cells at late stages of growth. Diglyceride acyltransferase [EC 2.3.1.20] activity was detected in a cell-free extract from this bacterium. The pH optimum of this enzyme was between pH 7 and 9. F- and Tween 20 showed remarkable enhancing and inhibitory effects, respectively. 相似文献
94.
Summary We have characterized the two dominant genes, IND 1 and IND 2, responsible for inducible sexual agglutinability. The strains carrying these genes differ from the inducible strains carrying the recessive gene, saa 1 in the following points. The former strains produce agglutination substance at 22°, 28°, and 37° C only in response to sex pheromone of the opposite mating type, but the latter strains produce the substance constitutively without the pheromone at 22° C, only in response to the pheromone at 28° C, and do not produce the substance, even in the presence of the pheromone, at 37° C.We suggest that strains carrying one of the dominant, inducible genes are wild type and have a pheromone-controlled regulatory system of sexual agglutinability. 相似文献
95.
Hiroki Nakagawa Shinji Ishigami Kiyoshi Sekiguchi Kunio Kurata Nagao Ogura 《Phytochemistry》1981,20(6):1229-1230
Evidence is presented for the selective breakdown of altered tomato β-fructofuranosidase molecules by a neutral protease from Bacillus subtilis. 相似文献
96.
97.
Shoko Nakano Yuko Abe Kimiko Nakajima Shigetoshi Sano Osamu Yamamoto Kazumasa Wakamatsu Shosuke Ito Masahiro Hayashi Tamio Suzuki 《Pigment cell & melanoma research》2021,34(1):101-110
Post‐inflammatory hyperpigmentation (PIH) is a common cutaneous condition that can cause a disfigured appearance. However, the pathophysiology of PIH remains poorly understood, at least in part, because an appropriate animal model for research has not been established. In order to analyze the pathomechanism of PIH, we successfully induced PIH in a hairless version of transgenic mice (hk14‐SCF Tg/HRM) that have a human‐type epidermis containing melanin by repeated hapten application of 2,4‐dinitrofluorobenzene. Histopathologic observation showed epidermal hyperplasia, predominant infiltrations of inflammatory cells, and melanin‐containing cells in the dermis just after elicitation of the atopic dermatitis‐like condition. At week 2, the findings were similar to the characteristics of PIH, that is, an increase of melanin without spongiosis or liquid degeneration in the epidermis and an increase in dermal melanophages. Dynamic analysis of melanin showed that the melanin in the dermis remained for a longer duration than in the epidermis. Furthermore, immunohistochemical staining revealed that the majority of cells containing melanin were positive for the anti‐CD68 antibody, but negative for the anti‐F4/80 antibody. These data suggest that novel treatments of PIH should be targeted against macrophages and should eventually lead to the development of new treatment modalities. 相似文献
98.
Shota Tanaka Mika Hosokawa Takumi Miyamoto Aiko Nakagawa Mika Haruna Kumiko Ueda Seigo Iwakawa Ken-ichi Ogawara 《Biochemistry and Biophysics Reports》2021
microRNAs (miRNAs) contained in small extracellular vesicles (sEVs) are candidates for non-invasive biomarkers. Oxaliplatin (L-OHP) has been approved for advanced colorectal cancer (CRC) chemotherapy. However, the response to L-OHP differs among CRC patients. In addition, CRC cells often acquire the resistance to L-OHP. This study aimed at the prediction of L-OHP sensitivity by measuring extracellular miRNAs levels. Firstly, we compared intracellular miRNAs expressions in L-OHP-sensitive CRC cells (SW620 and HCT116 cells) with those in acquired and intrinsic L-OHP-resistant cells. In microarray and real-time RT-PCR analyses, the intracellular miR-33a-5p, miR-210–3p, and miR-224–5p expressions were lower in acquired and intrinsic L-OHP-resistant CRC cells than sensitive cells. Furthermore, in SW620 cells, L-OHP sensitivity was decreased by miR-33a-5p inhibitor. On the other hand, miR-210–3p or miR-224–5p inhibitor did not affect L-OHP sensitivity in SW620 cells. Secondly, the amount of miR-33a-5p, miR-210–3p, and miR-224–5p in sEVs was compared. The amount of miR-33a-5p and miR-210–3p in sEVs secreted from acquired and intrinsic L-OHP-resistant cells tended to be small. miR-224–5p was not detected in sEVs secreted from three types of CRC cells examined. To the best of our knowledge, this is the first study demonstrating that miR-33a-5p and/or miR-210–3p in sEVs would be candidates for biomarkers of L-OHP sensitivity. In particular, miR-33a-5p is a promising candidate because it would be directly involved in L-OHP sensitivity. 相似文献
99.
Nobuho Tanaka Yasuko Ikeda Tetsuo Yamaguchi Hiroshi Furukawa Hiroyuki Mitomi Takumi Nakagawa Shigeto Tohma Naoshi Fukui 《Arthritis research & therapy》2013,15(5):R127
Introduction
Articular chondrocytes undergo an obvious phenotypic change when cultured in monolayers. During this change, or dedifferentiation, the expression of type I and type III procollagen is induced where normal chondrocytes express little type I and type III procollagen. In this study, we attempted to determine the mechanism(s) for the induction of such procollagen expression in dedifferentiating chondrocytes.Methods
All experiments were performed using primary-cultured human articular chondrocytes under approval of institutional review boards. Integrin(s) responsible for the induction of type I and type III procollagen expression were specified by RNAi experiments. The signal pathway(s) involved in the induction were determined by specific inhibitors and RNAi experiments. Adenovirus-mediated experiments were performed to identify a small GTPase regulating the activity of integrins in dedifferentiating chondrocytes. The effect of inhibition of integrins on dedifferentiation was investigated by experiments using echistatin, a potent disintegrin. The effect of echistatin was investigated first with monolayer-cultured chondrocytes, and then with pellet-cultured chondrocytes.Results
In dedifferentiating chondrocytes, α5β1 integrin was found to be involved in the induction of type I and type III procollagen expression. The induction was known to be mediated by v-akt murine thymoma viral oncogene homolog (AKT) signaling. Among the three AKT isoforms, AKT1 seemed to be most involved in the signaling. Elated RAS viral (r-ras) oncogene homolog (RRAS) was considered to regulate the progression of dedifferentiation by modulating the affinity and avidity of α5β1 integrin to ligands. Echistatin inhibited dedifferentiation of monolayer-cultured chondrocytes. Furthermore, the matrix formed by pellet-cultured chondrocytes more closely resembled that of normal cartilage compared with the controls.Conclusions
The result of this study has shown, for the first time, that α5β1 integrin may be responsible for the induction of non-cartilaginous collagen expression in chondrocytes undergoing dedifferentiation. Again, this study has shown that the inhibition of ligand ligation to integrins may be an effective strategy to inhibit phenotypic change of cultured chondrocytes, and to improve the quality of matrix synthesized by primary cultured chondrocytes. 相似文献100.