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101.
Activation of ROCK by RhoA is regulated by cell adhesion, shape, and cytoskeletal tension 总被引:3,自引:0,他引:3
Bhadriraju K Yang M Alom Ruiz S Pirone D Tan J Chen CS 《Experimental cell research》2007,313(16):3616-3623
Adhesion to the extracellular matrix regulates numerous changes in the actin cytoskeleton by regulating the activity of the Rho family of small GTPases. Here, we report that adhesion and the associated changes in cell shape and cytoskeletal tension are all required for GTP-bound RhoA to activate its downstream effector, ROCK. Using an in vitro kinase assay for endogenous ROCK, we found that cells in suspension, attached on substrates coated with low density fibronectin, or on spreading-restrictive micropatterned islands all exhibited low ROCK activity and correspondingly low myosin light chain phosphorylation, in the face of high levels of GTP-bound RhoA. In contrast, allowing cells to spread against substrates rescued ROCK and myosin activity. Interestingly, inhibition of tension with cytochalasin D or blebbistatin also inhibited ROCK activity within 20 min. The abrogation of ROCK activity by cell detachment or inhibition of tension could not be rescued by constitutively active RhoA-V14. These results suggest the existence of a feedback loop between cytoskeletal tension, adhesion maturation, and ROCK signaling that likely contributes to numerous mechanochemical processes. 相似文献
102.
Hua Zhang Zhu-Qin Tan Lan-Ying Hu Song-Hua Wang Jian-Ping Luo Russell L. Jones 《植物学报(英文版)》2010,52(6):556-567
Protective role of hydrogen sulfide (H2S) on seed germination and seedling growth was studied in wheat (Triticum) seeds subjected to aluminum (Al3+) stress. We show that germination and seedling growth of wheat is inhibited by high concentrations of AICI3. At 30 mmol/L AICI3 germination is reduced by about 50% and seedling growth is more dramatically inhibited by this treatment. Pre-incubation of wheat seeds in the H2S donor NaHS alleviates AICI3-induced stress in a dose-dependant manner at an optimal concentration of 0.3 mmol/L. We verified that the role of NaHS in alleviating Al3+ stress could be attributed to H2S/HS- by showing that the level of endogenous H2S increased following NaHS treatment. Furthermore, other sodium salts containing sulfur were ineffective in alleviating Al3+ stress. NaHS pretreatment significantly increased the activities of amylases and esterases and sustained much lower levels of MDA and H2O2 in germinating seeds under Al3+ stress. Moreover, NaHS pretreatment increased the activities of guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase and catalase and decreased that of lipoxygenase. NaHS pretreatment also decreased the uptake of Al3+ in AICI3-treated seed. Taken together these results suggest that H2S could increase antioxidant capability in wheat seeds leading to the alleviation of Al3+ stress. 相似文献
103.
104.
Fetal cells migrate into the mother during pregnancy. Fetomaternal transfer probably occurs in all pregnancies and in humans the fetal cells can persist for decades. Microchimeric fetal cells are found in various maternal tissues and organs including blood, bone marrow, skin and liver. In mice, fetal cells have also been found in the brain. The fetal cells also appear to target sites of injury. Fetomaternal microchimerism may have important implications for the immune status of women, influencing autoimmunity and tolerance to transplants. Further understanding of the ability of fetal cells to cross both the placental and blood-brain barriers, to migrate into diverse tissues, and to differentiate into multiple cell types may also advance strategies for intravenous transplantation of stem cells for cytotherapeutic repair. Here we discuss hypotheses for how fetal cells cross the placental and blood-brain barriers and the persistence and distribution of fetal cells in the mother.Key Words: fetomaternal microchimerism, stem cells, progenitor cells, placental barrier, blood-brain barrier, adhesion, migrationMicrochimerism is the presence of a small population of genetically distinct and separately derived cells within an individual. This commonly occurs following transfusion or transplantation.1–3 Microchimerism can also occur between mother and fetus. Small numbers of cells traffic across the placenta during pregnancy. This exchange occurs both from the fetus to the mother (fetomaternal)4–7 and from the mother to the fetus.8–10 Similar exchange may also occur between monochorionic twins in utero.11–13 There is increasing evidence that fetomaternal microchimerism persists lifelong in many child-bearing women.7,14 The significance of fetomaternal microchimerism remains unclear. It could be that fetomaternal microchimerism is an epiphenomenon of pregnancy. Alternatively, it could be a mechanism by which the fetus ensures maternal fitness in order to enhance its own chances of survival. In either case, the occurrence of pregnancy-acquired microchimerism in women may have implications for graft survival and autoimmunity. More detailed understanding of the biology of microchimeric fetal cells may also advance progress towards cytotherapeutic repair via intravenous transplantation of stem or progenitor cells.Trophoblasts were the first zygote-derived cell type found to cross into the mother. In 1893, Schmorl reported the appearance of trophoblasts in the maternal pulmonary vasculature.15 Later, trophoblasts were also observed in the maternal circulation.16–20 Subsequently various other fetal cell types derived from fetal blood were also found in the maternal circulation.21,22 These fetal cell types included lymphocytes,23 erythroblasts or nucleated red blood cells,24,25 haematopoietic progenitors7,26,27 and putative mesenchymal progenitors.14,28 While it has been suggested that small numbers of fetal cells traffic across the placenta in every human pregnancy,29–31 trophoblast release does not appear to occur in all pregnancies.32 Likewise, in mice, fetal cells have also been reported in maternal blood.33,34 In the mouse, fetomaternal transfer also appears to occur during all pregnancies.35 相似文献
105.
镜鲤体长性状的QTL定位分析 总被引:1,自引:0,他引:1
以镜鲤良种后代为祖父母本所培育的杂交F2群体的68个个体为材料,利用553个分子标记(217个SSR和336个SNP标记)对其进行基因型检测,运用JoinMap4.0软件包对遗传连锁图谱进行构建。利用MapQTL5.0区间作图法(Interval mapping)进行QTL检测,通过置换实验(1 000次重复)确定连锁群显著性水平阈值。在对体长的区间定位中共检测到12个与体长性状相关的QTLs区间,分布在BL-1-1(SNP0137-SNP1481)、BL-4-1(SNP0092-HLJ797)、BL-5-1(SNP1268-HLJ423)、BL-7-1(HLJ870-SNP0702)、BL-12-1(SNP0922-HLJ639)、BL-16-1(HLJE351-SNP0674)、BL-25-1(SNP0394-SNP0862)、BL-35-1(HLJ668-SNP0832)、BL-43-1(SNP0389-SNP1425)、BL-47-1(HLJ057-HLJ1113)、BL-47-2(HLJ1439-HLJ1418)等11个连锁群上,解释表型变异范围是13.8%~64.9%,其中贡献率大于20%的主效QTLs有8个,是体长性状的主效QTLs区间。 相似文献
106.
107.
To overcome the high energy-consuming process of microalgae drying, a two-step lipase catalysis technique for the preparation of biodiesel from microalgae lipid of Chlorella spp. was developed. In the first step, free fatty acids (FAAs) and triacylglycerols (TAGs) are released after cell disruption and extracted, while the TAGs were hydrolysed by free lipase in aqueous phase. In the second step, FAAs were esterified with ethanol in the catalysis of free suspended lipase. The maximum rate of hydrolysis and esterification was 93.6% and 91.3%, respectively. The effects of reaction parameters, such as reaction time, enzyme amount, water content and molar ratio of lipid to ethanol on hydrolysis or esterification, were investigated. The results indicated that two-step reaction process (hydrolyse esterify) for biodiesel production were feasible. 相似文献
108.
Chuanbin Yang Cui-Zan Cai Ju-Xian Song Jie-Qiong Tan Siva Sundara Kumar Durairajan Ashok Iyaswamy 《Autophagy》2017,13(12):2028-2040
Alzheimer disease (AD) is the most common neurodegenerative disease characterized by the deposition of amyloid plaque in the brain. The autophagy-associated PIK3C3-containing phosphatidylinositol 3-kinase (PtdIns3K) complex has been shown to interfere with APP metabolism and amyloid beta peptide (Aβ) homeostasis via poorly understood mechanisms. Here we report that NRBF2 (nuclear receptor binding factor 2), a key component and regulator of the PtdIns3K, is involved in APP-CTFs homeostasis in AD cell models. We found that NRBF2 interacts with APP in vivo and its expression levels are reduced in hippocampus of 5XFAD AD mice; we further demonstrated that NRBF2 overexpression promotes degradation of APP C-terminal fragments (APP-CTFs), and reduces Aβ1–40 and Aβ1-42 levels in human mutant APP-overexpressing cells. Conversely, APP-CTFs, Aβ1–40 and Aβ1-42 levels were increased in Nrbf2 knockdown or nrbf2 knockout cells. Furthermore, NRBF2 positively regulates autophagy in neuronal cells and NRBF2-mediated reduction of APP-CTFs levels is autophagy dependent. Importantly, nrbf2 knockout attenuates the recruitment of APP and APP-CTFs into phagophores and the sorting of APP and APP-CTFs into endosomal intralumenal vesicles, which is accompanied by the accumulation of the APP and APP-CTFs into RAB5-positive early endosomes. Collectively, our results reveal the potential connection between NRBF2 and the AD-associated protein APP by showing that NRBF2 plays an important role in regulating degradation of APP-CTFs through modulating autophagy. 相似文献
109.
Polygonum melihae Gemici & Kit Tan sp. nov. (Polygonaceae), a local endemic of inner west Anatolia is described as a species new to science and illustrated by photographs. The closest affinities are with P. afyonicum and P. setosum. Morphological characteristics and information about ecology and distribution are provided and the three taxa are compared. Dissimilarities with two Greek endemics, P. papillosum and P. idaeum, are also mentioned. 相似文献
110.
To improve efficiency and assess variation in nuclear transfer techniques in non-human primates, we investigated the following factors: type of donor cell, interval between enucleation and cell injection, activation after electrical pulsing and cytokinesis inhibitors. An average of 16.4 oocytes were recovered from 91 retrievals; however, 15 (14%) additional retrieval attempts yielded no oocytes due to a failure of follicular stimulation. Oocyte maturation rates at 36, 38 and 40 h post-hCG were 46.2, 52.6 and 61.2%, respectively. The MII spindle could be seen clearly using polarized microscopy in 89.1% (614/689) of oocytes. Nuclei were seen in 42% of the NT couplets, 53% of those cleaved to the 2-cell stage and 63% of the 2-cell embryos developed to the 8-cell stage by Day 3. There was no difference in the occurrence of nuclear formation between couplets created using fibroblasts or cumulus cells, although embryos were more reliably produced with fibroblasts. The interval (2, 3 and 4 h) between enucleation and cell injection did not affect NT efficiency. Ethanol treatment after electrical pulses yielded more 2-cell NT embryos than did treatment with ionomycin, but the frequency of nuclear formation and development to the 8-cell stage was not different. Treatment of couplets with cycloheximide and cytochalasin B for 5 h after activation had no impact on NT efficiency. 相似文献