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61.
Kohichi Kojima Makio Mogi Kazuhiro Oka Toshiharu Nagatsu 《Neurochemistry international》1984,6(4):475-480
Tyrosine hydroxylase (TH) was purified from the soluble fraction of human adrenal glands. The enzyme in human adrenal glands that was purified to apparent homogeneity had an apparent Mr of about 280,000. Sodium dodecyl sulfate (SDS) gel electrophoresis gave a single band with a Mr of 60,000 similar to the Mr of bovine adrenal enzyme. The enzyme is considered to be composed of four identical subunits. The specific activity of the final preparation was approximately 310 nmol 3,4-dihydroxyphenylalanine (DOPA) formed/min/mg protein. The use of the “Western Blot” method showed that human adrenal TH did not aggregate as rapidly as bovine adrenal TH. 相似文献
62.
Ying Chen Yousuke Shimoda Makio Yokono Hisashi Ito Ayumi Tanaka 《The Plant journal : for cell and molecular biology》2019,97(6):1022-1031
The STAY‐GREEN (SGR) gene encodes Mg‐dechelatase which catalyzes the conversion of chlorophyll (Chl) a to pheophytin (Pheo) a. This reaction is the first and most important regulatory step in the Chl degradation pathway. Conversely, Pheo a is an indispensable molecule in photosystem (PS) II, suggesting the involvement of SGR in the formation of PSII. To investigate the physiological functions of SGR, we isolated Chlamydomonas sgr mutants by screening an insertion‐mutant library. The sgr mutants had reduced maximum quantum efficiency of PSII (Fv/Fm) and reduced Pheo a levels. These phenotypes were complemented by the introduction of the Chlamydomonas SGR gene. Blue Native polyacrylamide gel electrophoresis and immunoblotting analysis showed that although PSII levels were reduced in the sgr mutants, PSI and light‐harvesting Chl a/b complex levels were unaffected. Under nitrogen starvation conditions, Chl degradation proceeded in the sgr mutants as in the wild type, indicating that ChlamydomonasSGR is not required for Chl degradation and primarily contributes to the formation of PSII. In contrast, in the Arabidopsis sgr triple mutant (sgr1 sgr2 sgrL), which completely lacks SGR activity, PSII was synthesized normally. These results suggest that the Arabidopsis SGR participates in Chl degradation while the ChlamydomonasSGR participates in PSII formation despite having the same catalytic property. 相似文献
63.
Naturally arising CD4(+)CD25(+)FoxP3(+) regulatory T cells (nTregs) have an essential role in maintenance of immune homeostasis and peripheral tolerance. Previously, we reported that conventional CD4(+) and CD8(+) T cells undergo p53-induced CD28-dependent apoptosis (PICA) when stimulated with a combination of immobilized anti-CD3 and anti-CD28 Abs, whereas nTregs expand robustly under the same conditions, suggesting that there is a differential survival mechanism against PICA between conventional T cells and nTregs. In this study, we demonstrate that TGF-β signaling is required for nTregs to survive PICA. Conversely, when an active form of exogenous TGF-β is present, conventional T cells become resistant to PICA and undergo robust expansion instead of apoptosis, with reduction of the proapoptotic protein Bim and FoxO3a. A substantial fraction of PICA-resistant T cells expressed IL-9 (T(H)9 cells). Moreover, the presence of IL-6 along with TGF-β led to the generation of T(H)17 cells from conventional T cells. Together, the data demonstrate a novel role for TGF-β in the homeostasis of regulatory T cells and effector T cell differentiation and expansion. 相似文献
64.
The midgut plays a major role in digestion and absorption of nutrients in insects, and contains endocrine cells throughout the epithelial layer that express neuropeptides, including crustacean cardioactive peptide (CCAP). In the present study, we demonstrate regulation of digestive enzyme activities by CCAP in response to nutrient ingestion in the cockroach, Periplaneta americana. The midgut of the cockroach exhibits maximal alpha-amylase and protease activities 3 h after intake of either starch or casein, but not of non-nutrients. Similar time-dependent responses of CCAP expression in midgut endocrine cells were observed after feeding starch and casein, but not after non-nutrients. We also show that incubation of the dissected midgut with CCAP leads to an increase in alpha-amylase and protease activity in a time-dependent manner, with the maximal activity at 2 h. Taken together, our data indicate the existence of an inducible mechanism where endocrine cells in the midgut are stimulated to synthesize and secrete CCAP by nutrients, and CCAP then up-regulates the activity of digestive enzymes. 相似文献
65.
Fukushima A Hatanaka Y Chang JW Takamatsu M Singh N Iwashima M 《Cellular signalling》2006,18(8):1182-1189
Recent genetic evidence demonstrated that Shc is a critical molecule for T cell activation and differentiation. However, how Shc is coupled to the T cell antigen receptor (TCR) has not been clearly characterized. Here we report that the tyrosine kinase Lck functions as a connecting molecule for TCR and Shc. Lck plays a critical role in TCR signal transduction by phosphorylating the immuno-receptor tyrosine based activation motif (ITAM). Our data shows that the PTB domain of Shc binds the SH2/3 domains of Lck in a phosphotyrosine-independent manner. Inhibition of the Lck/Shc interaction led to the loss of IL-2 promoter activation, confirming that the role of Shc in IL-2 production requires its interaction with Lck. Together, the data show that Shc is connected to the activated TCR via direct interaction with Lck. 相似文献
66.
67.
Imaginal disc growth factor (IDGF) is a soluble polypeptide growth factor that was first identified from the conditioned medium of Drosophilia imaginal disc C1.8+ cells. Working with insulin, IDGF stimulated the growth of cultured imaginal disk cells, which suggested that IDGF might function as a cofactor of Drosophila insulin or insulin like peptide. Here we report a new member of the IDGF family, named MbIDGF, from the cabbage armyworm, Mamestra brassicae. Using a cloned cDNA of MbIDGF, recombinant MbIDGF protein was expressed in baculovirus-infected Sf9 cells and purified. Without insulin, the recombinant MbIDGF protein stimulated cell growth of SES-MaBr-4 and NIAS-MaBr-93 cell lines that were derived from the fat bodies and hemocytes of M. brassicae, in a dose-dependent manner. The saturation of growth stimulation by MbIDGF was attained for the two types of cells at 80 ng/ml (0.8 nM) and 300 ng/ml (6 nM), respectively. The results suggest that MbIDGF may stimulate the growth of lepidopteran cells by a new mechanism without associating with the insulin pathway. 相似文献
68.
The effects of starvation on cell death in the midgut of Periplaneta americana were studied histochemically and ultrastructurally. TUNEL assays showed that cell death began to increase in the columnar
cells and nidi, the nests of stem cells and newborn cells from 2 weeks of starvation. A significant increase in cell death
occurred in the nidi after 4 weeks of starvation. Cockroaches starved for 4 weeks showed active-caspase-3-like immuno-reactivity
both in the columnar cells and nidi, whereas control cockroaches that were fed for 4 weeks showed this reactivity only in
the apical cytoplasm of columnar cells. Electron microscopy revealed no chromatin condensation in the nucleus of columnar
cells of cockroaches, whether fed or starved for 4 weeks. Starved cockroaches exhibited many small vacuoles in the cytoplasm
of some columnar cells and “floating” organelles including nuclei in the lumen. A 4-week starvation induced the appearance
of cytoplasmic fragmentation and secondary lysosomes in the nidi. Each fragment contained nuclear derivatives with condensed
chromatin, i.e. apoptotic bodies. Mitotic cells were found in some, but not all nidi, even within the same starved sample.
Fragmentation was not observed in the nidi of control cockroaches. Thus, starvation increases cell death not only in the columnar
cells, but also in the nidi. The cell death in the nidi is presumably apoptosis executed by caspase 3. 相似文献
69.
Norimitsu Izawa Takeshi Suzuki Masakatsu Watanabe Makio Takeda 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2009,152(4):346-351
Arylalkylamine N-acetyltransferase (AANAT), constituting a large family of enzymes, catalyzes the transacetylation from acetyl-CoA to monoamine substrates, although homology among species is not very high. AANAT in vertebrates is photosensitive and mediates circadian regulation. Here, we analyzed AANAT of the cricket, Dianemobius nigrofasciatus. The central nervous system contained AANAT activity. The optimum pHs were 6.0 (a minor peak) and 10.5 (a major peak) with crude enzyme solution. We analyzed the kinetics at pH 10.5 using the sample containing collective AANAT activities, which we term AANAT. Lineweaver-Burk plot and secondary plot yielded a Km for tryptamine as substrate of 0.42 µM, and a Vmax of 9.39 nmol/mg protein/min. The apparent Km for acetyl-CoA was 59.9 µM and the Vmax was 8.14 nmol/mg protein/min. AANAT of D. nigrofasciatus was light-sensitive. The activity was higher at night-time than at day-time as in vertebrates. To investigate most effective wavelengths on AANAT activity, a series of monochromatic lights was applied (350, 400, 450, 500, 550, 600 and 650 nm). AANAT showed the highest sensitivity to around 450 nm and 550 nm. 450 nm light was more effective than 550 nm light. Therefore, the most effective light affecting AANAT activity is blue light, which corresponds to the absorption spectrum of blue wave (BW)-opsin. 相似文献
70.
Aya Kawasaki Satoshi Ito Hiroshi Furukawa Taichi Hayashi Daisuke Goto Isao Matsumoto Makio Kusaoi Jun Ohashi Robert R Graham Kunio Matsuta Timothy W Behrens Shigeto Tohma Yoshinari Takasaki Hiroshi Hashimoto Takayuki Sumida Naoyuki Tsuchiya 《Arthritis research & therapy》2010,12(5):1-7