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991.
Selective regulation of neurite extension and synapse formation by the beta but not the alpha isoform of CaMKII 总被引:7,自引:0,他引:7
Neurite extension and branching are important neuronal plasticity mechanisms that can lead to the addition of synaptic contacts in developing neurons and changes in the number of synapses in mature neurons. Here we show that Ca2+/calmodulin-dependent protein kinase II (CaMKII) regulates movement, extension, and branching of filopodia and fine dendrites as well as the number of synapses in hippocampal neurons. Only CaMKIIbeta, which peaks in expression early in development, but not CaMKIIalpha, has this morphogenic activity. A small insert in CaMKIIbeta, which is absent in CaMKIIalpha, confers regulated F-actin localization to the enzyme and enables selective upregulation of dendritic motility. These results show that the two main neuronal CaMKII isoforms have markedly different roles in neuronal plasticity, with CaMKIIalpha regulating synaptic strength and CaMKIIbeta controlling the dendritic morphology and number of synapses. 相似文献
992.
Ronald B. Myers Lan Wei John J. Castellot Jr. 《Journal of cell communication and signaling》2014,8(2):135-146
CCN proteins play crucial roles in cell motility, matrix turnover, and proliferation. In particular, CCN5 plays a role in cell motility and proliferation in several cell types; however, no functional binding proteins for CCN5 have been identified. In this study we report that CCN5 binds to the cell surface receptor integrin αvβ3 in vascular smooth muscle cells. Furthermore, this interaction takes place in podosomes, organelles known to degrade matrix and mediate motility. We show that CCN5 regulates the ability of podosomes to degrade matrix, but does not affect podosome formation. The level of CCN5 present in a podosome negatively correlates with its ability to degrade matrix. Conversely, knockdown of CCN5 greatly enhances the matrix-degrading ability of podosomes. These findings suggest that the antimotility effects of CCN5 may be mediated through the direct interaction of CCN5 and integrin αvβ3 in podosomes and the concomitant suppression of matrix degradation that is required for cell migration. 相似文献
993.
Wendy Kain Xiaozhao Song Alida F. Janmaat Jian-Zhou Zhao Judith Myers Anthony M. Shelton Ping Wang 《Applied and environmental microbiology》2015,81(5):1884-1890
Two populations of Trichoplusia ni that had developed resistance to Bacillus thuringiensis sprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. The T. ni colonies resistant to Bacillus thuringiensis serovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistant T. ni strains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in the T. ni populations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptible T. ni strain. The resistance to Cry2Ab in resistant T. ni was an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops. 相似文献
994.
BRCA2-dependent homologous recombination is required for repair of Arsenite-induced replication lesions in mammalian cells 下载免费PDF全文
Songmin Ying Katie Myers Sarah Bottomley Thomas Helleday Helen E. Bryant 《Nucleic acids research》2009,37(15):5105-5113
Arsenic exposure constitutes one of the most widespread environmental carcinogens, and is associated with increased risk of many different types of cancers. Here we report that arsenite (As[III]) can induce both replication-dependent DNA double-strand breaks (DSB) and homologous recombination (HR) at doses as low as 5 µM (0.65 mg/l), which are within the typical doses often found in drinking water in contaminated areas. We show that the production of DSBs is dependent on active replication and is likely to be the result of conversion of a DNA single-strand break (SSB) into a toxic DSB when encountered by a replication fork. We demonstrate that HR is required for the repair of these breaks and show that a functional HR pathway protects against As[III]-induced cytotoxicity. In addition, BRCA2-deficient cells are sensitive to As[III] and we suggest that As[III] could be exploited as a therapy for HR-deficient tumours such as BRCA1 and BRCA2 mutated breast and ovarian cancers. 相似文献
995.
Michael Lung Yulia V. Shulga Pavlina T. Ivanova David S. Myers Stephen B. Milne H. Alex Brown Matthew K. Topham Richard M. Epand 《The Journal of biological chemistry》2009,284(45):31062-31073
The phosphatidylinositol (PI) cycle mediates many cellular events by controlling the metabolism of many lipid second messengers. Diacylglycerol kinase ϵ (DGKϵ) has an important role in this cycle. DGKϵ is the only DGK isoform to show inhibition by its product phosphatidic acid (PA) as well as substrate specificity for sn-2 arachidonoyl-diacylglycerol (DAG). Here, we show that this inhibition and substrate specificity are both determined by selectivity for a combination of the sn-1 and sn-2 acyl chains of PA or DAG, respectively, preferring the most prevalent acyl chain composition of lipids involved specifically in the PI cycle, 1-stearoyl-2-arachidonoyl. Although the difference in rate for closely related lipid species is small, there is a significant enrichment of 1-stearoyl-2-arachidonoyl PI because of the cyclical nature of PI turnover. We also show that the inhibition of DGKϵ by PA is competitive and that the deletion of the hydrophobic segment and cationic cluster of DGKϵ does not affect its selectivity for the acyl chains of PA or DAG. Thus, this active site not only recognizes the lipid headgroup but also a combination of the two acyl chains in PA or DAG. We propose a mechanism of DGKϵ regulation where its dual acyl chain selectivity is used to negatively regulate its enzymatic activity in a manner that ensures DGKϵ remains committed to the PI turnover cycle. This novel mechanism of enzyme regulation within a signaling pathway could serve as a template for the regulation of enzymes in other pathways in the cell. 相似文献
996.
Q. E. Phelps M. R. Noatch H. A. Lewis D. J. Myers J. M. Zeigler J. S. Eichelberger M. J. Saltzgiver G. W. Whitledge 《Journal of fish biology》2009,75(10):2606-2614
The effect of digestion by a predatory fish (largemouth bass Micropterus salmoides) on stable isotopic (δ13C and δ18O) and trace elemental (Sr:Ca and Ba:Ca) compositions of prey fish (bluegill Lepomis macrochirus) otoliths was investigated in a laboratory experiment. Trace element and stable‐isotopic signatures of L. macrochirus otoliths were not significantly altered for up to 16 h after L. macrochirus were consumed by M. salmoides. Prey fish otoliths recovered from predator digesta can retain environmental stable isotopic and trace elemental signatures, suggesting that determination of environmental history for prey fishes by stable‐isotope and trace‐element analysis of otoliths recovered from stomachs of piscivorous fishes will be feasible. 相似文献
997.
本文综述了香菇(Lentinula edodes)的分类历史,确认其在蘑菇目(Agaricales)Tricholomataceae科下的分类地位,并证实了它与多孔菌目(Poriales)Lentinaceae科的Lentinus属没有联系。根据《真菌、地衣汉语学名命名法规》,作者讨论了译为“香菇属”的Lentinus和“小香菇属”的Lentinellus两属的汉语学名问题,提出Lentinus的汉语学名应订正为“韧伞属”,Lentinellus为“螺壳菌属”。香菇所在的Lentinula属的汉语学名建议为“木菇属”。 相似文献
998.
Root segments from shoot tip-derived plantlets of the garlic (Allium sativum L.) clones `DDR7099', `PI383819', and `Piacenza' were utilized as an explant source for continuous, friable callus production.
The best callus production occurred on root segments initially cultured on medium with 4,5 μm 2,4-dichlorophenoxyacetic acid (2,4-D) for 8 weeks, then subcultured to medium with 4.7 μm 4-amino-3,5,6-trichloropicolinic acid (picloram) +0.49 μm 6-(γ-γ-dimethylallylamino)purine (2iP) for 8 weeks. Embryogenic, friable callus was transferred to liquid medium for 1 month and
then transferred to solid regeneration medium for 14 weeks. The best shoot and root regeneration (85.3% and 35.8%, respectively)
occurred on 4-month-old calli from the clone `DDR7099'. In all clones, regeneration rate decreased as callus age increased.
Received: 14 October 1997 / Revision received: 26 December 1997 / Accepted: 12 January 1998 相似文献
999.
1000.
Vesoulis Z Rajappannair L Define L Beach J Vesoulis Z Schnell B Myers S 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2004,26(6):323-330
OBJECTIVE: To establish whether the results of quantitative evaluation of estrogen receptors (ERs) in cytologic fine needle aspiration (FNA) biopsies of the breast are comparable to the results obtained on excised breast tumors and therefore suitable for making a clinical decision on tamoxifen treatment in women who are not candidates for surgery. STUDY DESIGN: We performed a retrospective review of 118 breast FNA specimens that were positive for adenocarcinoma cells, had adequate cell block cellularity and provided subsequent surgical resection tissue. Quantification of ERs was performed on cell block material and follow-up tissue sections by the Chromavision Automated Imaging System, San Juan Capistrano, California, U.S.A. RESULTS: Quantitative image analysis provided consistently reliable, comparable results when evaluating for the presence or absence of ERs (at a 5% staining cutoff level), with 98.3% agreement between FNA cytology and histology specimens. Quantitative measurements of FNA samples showed the best agreement with the values derived from the subsequent surgical specimens at high-end (> 85% staining) and low-end (< 10% staining) values. However, a direct linear correlation of values was not observed. In the great majority of parallel measures, ERs were either strongly positive (> 75% staining) or had a zero value, particularly in the surgical specimens, with more "in-between" values identified in FNA specimens. CONCLUSION: Quantitative image analysis of FNA of ER results are comparable to those of surgical excision specimens and can be used for therapeutic decision making. The utility and advantages of quantitative ERs by image analysis include providing the patient and physician with important early prognostic and diagnostic information before planning a surgical approach. Additionally, FNA ERs are useful in determining therapy alternatives in patients who are not surgical candidates and in evaluating the preoperative hormone status of patients receiving chemotherapy prior to surgery. 相似文献