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Lila M. Landowski Macarena Pavez Lachlan S. Brown Robert Gasperini Bruce V. Taylor Adrian K. West Lisa Foa 《The Journal of biological chemistry》2016,291(3):1092-1102
The low-density lipoprotein receptor-related protein receptors 1 and 2 (LRP1 and LRP2) are emerging as important cell signaling mediators in modulating neuronal growth and repair. We examined whether LRP1 and LRP2 are able to mediate a specific aspect of neuronal growth: axon guidance. We sought to identify LRP1 and LRP2 ligands that could induce axonal chemoattraction, which might have therapeutic potential. Using embryonic sensory neurons (rat dorsal root ganglia) in a growth cone turning assay, we tested a range of LRP1 and LRP2 ligands for the ability to guide growth cone navigation. Three ligands were chemorepulsive: α-2-macroglobulin, tissue plasminogen activator, and metallothionein III. Conversely, only one LRP ligand, metallothionein II, was found to be chemoattractive. Chemoattraction toward a gradient of metallothionein II was calcium-dependent, required the expression of both LRP1 and LRP2, and likely involves further co-receptors such as the tropomyosin-related kinase A (TrkA) receptor. The potential for LRP-mediated chemoattraction to mediate axonal regeneration was examined in vivo in a model of chemical denervation in adult rats. In these in vivo studies, metallothionein II was shown to enhance epidermal nerve fiber regeneration so that it was complete within 7 days compared with 14 days in saline-treated animals. Our data demonstrate that both LRP1 and LRP2 are necessary for metallothionein II-mediated chemotactic signal transduction and that they may form part of a signaling complex. Furthermore, the data suggest that LRP-mediated chemoattraction represents a novel, non-classical signaling system that has therapeutic potential as a disease-modifying agent for the injured peripheral nervous system. 相似文献
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目的:肝脏是维持人体发挥功能的重要器官,同时肝脏再生能力十分强大。本文通过部分肝切除术后小鼠肝再生模型,观察肝再生过程中氧化应激及线粒体代谢变化规律,以期为将来的调控肝再生提供新的干预靶点。方法:选择雄性健康体重均匀的Balb/c小鼠,采用经典70%肝切除模型,随机分为假手术对照组(Sham组)以及70%肝切除组(70%PH组)。肝切除术后6 h、1d、2 d、3 d、5 d、7 d不同时间点取肝组织,制备冰冻切片检测活性氧(ROS)水平,Western blot分别检测细胞增殖相关蛋白PCNA、Cyclin D1;氧化应激相关蛋白SOD1、SOD2、CAT、GPX1;以及线粒体代谢相关蛋白PGC-1α、Nrf1、TFAM、Drp1、Fis1、Mfn1、Mfn2、OPA1的表达并分析其变化规律。结果:70%肝切除术后小鼠肝脏增长迅速,细胞增殖关键蛋白PCNA和Cyclin D1表达显著增加;在此过程中细胞ROS水平呈现先升高后降低的变化,细胞主要抗氧化酶SOD1、SOD2、CAT、Gpx1与ROS相一致出现先升高后降低的变化。线粒体生物合成调控因子PGC-1α、Nrf1、TFAM呈现先降低后升高的趋势,而线粒体分裂蛋白Drp1和Fis1呈现先降低后显著升高的趋势,线粒体融合相关蛋白Mfn1、Mfn2和OPA1总体为先降低后恢复至正常水平。结论:在小鼠70%肝切除再生过程中,存在着明显的氧化应激,线粒体生物合成增加,线粒体分裂/融合平衡偏向分裂,并且这些变化呈现具有一定的时间变化规律,这些变化及规律很可能作为将来调控肝再生的重要的潜在干预靶点。 相似文献
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LAURA K. SNOOK 《Botanical journal of the Linnean Society. Linnean Society of London》1996,122(1):35-46
Recent debate on whether or not mahogany ( Swietenia macrophylla King) is threatened by the international timber trade has focused on the breadth of its range and estimates of the remaining stock of mahogany trees. These data are inadequate to reveal the status of mahogany populations, both because they are incomplete in areal extent and because they do not reveal population parameters such as the existence or density of young trees smaller than commercial size. However, there is sufficient information on the regeneration ecology of mahogany to indicate that under natural conditions this species regenerates in essentially even-aged stands after catastrophic disturbances destroy many or most trees, and, in the case of fires and flooding, saplings and seedlings as well. Adult mahoganies tend to survive these events, and regenerate by shedding seed onto the resulting gaps or clearings. This ecological strategy makes mahogany vulnerable to logging, first because juvenile mahoganies are not found in the understorey, and secondly because logging operations shortcircuit mahogany regeneration processes by selectively removing almost all mahogany seed sources while leaving standing competing vegetation of other species. Listing of mahogany in CITES Appendix II could provide both a mechanism to fill in gaps in information and an incentive to change current practices in favour of silvicultural management to provide for regeneration of this valuable timber species in forests subjected to logging. 相似文献
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再生稻褐飞虱为害损失测定和防治指标的研究 总被引:1,自引:0,他引:1
在福建,褐飞虱是再生稻的重要害虫,中进行了再生稻褐飞虱为害损失的测定,并对褐飞虱为害再生稻造成的产量损失结构进行了通径分析。根据虫量和产量损失的关系,结合现行稻谷价格,产量水平,防治费用等因素。确定允许为害损失率,同时建立了再生稻褐飞虱防治指标模型,按照防治指标模型,制定出不同产量水平的防治指标。 相似文献
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Summary Protoplasts were isolated from immature cotyledons of Vigna sinensis and cultured in a modified MS Liquid medium containing 0. 2 mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D), 1 mg/l naphthaleneacetic acid (NAA) and 0. 5 mg/l 6-benzylaminopurine (BAP) in the dark at a density of 1 × 105/ml. The protoplasts began to divide in 3–5 days. Sustained cell division resulted in formation of cell clusters and small calli, with the cell division frequency and plating efficiency of cell colonies reaching 27. 7% and 1. 7% respectively. When calli of 2 mm in size were transferred onto MSB medium (MS salts and B5 vitamins) containing 500mg/l NaCl, 500 mg/ 1 casein hydrolysate (CH), 2 mg/l 2,4-D and 0. 5 mg/l BAP for further growth, approximately 5% of the calli developed embryogenically. The embryogenic calli were selected and subcultured on the same composition of MSB medium and were able to maintain somatic embryogenesis capacity in subculture for a long time. When the calli were moved to MSB medium with 0. 1 mg/l indole-3-acetic acid (IAA), 0. 5mg/l kinetin(KT), 3–5% mannitol and 2% sucrose in the light, many somatic embryos formed from the calli. Only part of the embryoids developed further to the cotyledonary stage, and the others died at the globular, heart-shaped or torpedo stages. Finally, some cotyledonary embryoids germinated and developed into plants or shoots. The shoots were readily rooted on 1/2 strength MS medium with 0. 1–0.3 mg/l indole-3-butyric acid (IBA). The plants grew well in soil and were fertile.Abbreviations 2, 4-D
dichlorophenoxyacetic acid
- NAA
naphthaleneacetic acid
- BAP
6-benzylaminopurine
- IAA
indole-3-acetic acid
- KT
kinetin
- IBA
indole-3-butyric acid
- CH
casein hydrolysate
- CM
coconut milk
- ZT
zeatin 相似文献
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Somatic embryogenesis from pea embryos and shoot apices 总被引:3,自引:0,他引:3
Conditions were defined for plant regeneration via somatic embryogenesis in pea, using explants from immature zygotic embryos or from shoot apices. For the induction of somatic embryos, an auxin (picloram or 2,4-dichlorophenoxyacetic acid) was required. Embryogenic callus originated from embryonic axis tissue of immature embryos and from the axillary-bud region and the plumula of shoot apices. A clear effect of embryo size on somatic embryogenesis was shown. There were differences in frequency of somatic embryogenesis among the five genotypes used in the study. Additions of BA to auxin-containing medium reduced embryo production. Histological examinations confirmed the embryogenic nature of the immature embryo cultures and revealed that somatic embryos originated from the meristematic areas near the callus surface.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- NAA
naphthaleneacetic acid
- picloram
4-amino-3,5,6-trichloropicolinic acid 相似文献