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121.
W. J. Brad Hanna Jane Anne Horne George H. Renninger 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,162(1):127-132
The circadian rhythm in the ERG amplitude of the lateral compound eye ofLimulus can be phase shifted either by general illumination or by illuminating combinations of the photoreceptor organs.
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1. | For 15-min exposures, light confined to one lateral eye, or to the median ocelli, or to the ventral photoreceptor region resulted in the smallest phase shifts. |
2. | Illuminating combinations of these organs produced larger shifts. The most effective combination tested included the median ocelli, the ventral photoreceptors, and one lateral eye. The phase shift resulting from illumination of this combination was only about one-half of the shift produced by general illumination. |
3. | These results suggest that the circadian clock also receives light information from other, unidentified, photoreceptors located outside the prosoma. |
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Zhao L Samuels T Winckler S Korgaonkar C Tompkins V Horne MC Quelle DE 《Molecular cancer research : MCR》2003,1(3):195-206
Cyclin G1 is a p53-responsive gene that is induced in alternative reading frame (ARF)-arrested cells, yet its role in growth control is unclear. We tested its effects on growth and involvement in the ARF-Mdm2-p53 tumor suppressor pathway. We show that cyclin G1 interacts with ARF, Mdm2, and p53 in vitro and in vivo. At high levels, cyclin G1 induces a G(1)-phase arrest in mammalian cells that coincides with p53 activation. Conversely, lower levels of cyclin G1 lack intrinsic growth inhibitory effects yet potentiate ARF-mediated growth arrest. Notably, cyclin G1 is down-regulated by Mdm2 through proteasome-mediated degradation. These data suggest that cyclin G1 is a positive feedback regulator of p53 whose expression is restrained by Mdm2. Interestingly, growth inhibition by cyclin G1 does not require p53 but instead exhibits partial retinoblastoma protein (pRb) dependence. These findings reveal that cyclin G1 has growth inhibitory activity that is mechanistically linked to ARF-p53 and pRb tumor suppressor pathways. 相似文献
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c-Cbl and Cbl-b Act Redundantly to Protect Osteoclasts from Apoptosis and to Displace HDAC6 from β-Tubulin,Stabilizing Microtubules and Podosomes
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Enkhtsetseg Purev Lynn Neff William C. Horne Roland Baron 《Molecular biology of the cell》2009,20(18):4021-4030
c-Cbl and Cbl-b are highly conserved adaptor proteins that participate in integrin signaling, regulating cytoskeletal organization, motility, and bone resorption. Deletion of both c-Cbl and Cbl-b in mice leads to embryonic lethality, indicating that the two proteins perform essential redundant functions. To examine the redundant actions of c-Cbl and Cbl-b in osteoclasts, we depleted c-Cbl in Cbl-b−/− osteoclasts by using a short hairpin RNA. Depleting both Cbl proteins disrupted both the podosome belt and the microtubule network and decreased bone-resorbing activity. Stabilizing the microtubules with paclitaxel or inhibiting histone deacetylase 6 (HDAC6), which destabilizes microtubules by deacetylating β-tubulin, protected both the microtubule network and the podosome belt. Examination of the mechanism involved demonstrated that the conserved four-helix bundle of c-Cbl''s tyrosine kinase binding domain bound to β-tubulin, and both c-Cbl and Cbl-b displaced HDAC6. In addition to the effects on microtubules and the podosome belt, depleting both Cbls significantly increased the levels of the proapoptotic protein Bim and apoptosis relative to the levels induced by eliminating either protein alone. Thus, both c-Cbl and Cbl-b promote bone resorption via the stabilization of microtubules, allowing the formation of the podosome belt in osteoclasts, and by promoting osteoclast survival. 相似文献
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The immobilization isotherms of Clostridium thermocellum cells on bituminous coal particles of approximately 0.15- to 0.18-mm diameter were experimentally measured at 60, 45, and 30 degrees C with a pH value of 7.0 and with pH values of 6.0 and 5.0 at 60 degrees C. The immobilization data were correlated into Langmuir forms and their characteristic coefficients were obtained. A method to obtain thermodynamic quantities delta G, delta H, and delta S for the immobilization is also demonstrated. 相似文献
127.
Enzymatic preparation of high specific activity radiolabeled (I)-L-5-methyltetrahydropteroylglutamate 总被引:2,自引:0,他引:2
5-CH3[G-3H]H4PteGlu (sp act 5.0 Ci/nmol) was synthesized by direct enzymatic reduction of [G-3H]PteGlu by dihydropteroylglutamate reductase to H4PteGlu. The latter was reacted with formaldehyde to give 5,10-CH2-H4-PteGlu which was reduced to the final product by sodium borohydride. A single chromatographic step on TEAE-cellulose afforded 5-CH3[G-3H]H4PteGlu in high yield at a radiochemical purity of about 99%. 相似文献
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