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151.
Rac is a dominant regulator of cadherin-directed actin assembly that is activated by adhesive ligation independently of Tiam1 总被引:1,自引:0,他引:1
Kraemer A Goodwin M Verma S Yap AS Ali RG 《American journal of physiology. Cell physiology》2007,292(3):C1061-C1069
Classic cadherins function as adhesion-activated cell signaling receptors. On adhesive ligation, cadherins induce signaling cascades leading to actin cytoskeletal reorganization that is imperative for cadherin function. In particular, cadherin ligation activates actin assembly by the actin-related protein (Arp)2/3 complex, a process that critically affects the ability of cells to form and extend cadherin-based contacts. However, the signaling pathway(s) that activate Arp2/3 downstream of cadherin adhesion remain poorly understood. In this report we focused on the Rho family GTPases Rac and Cdc42, which can signal to Arp2/3. We found that homophilic engagement of E-cadherin simultaneously activates both Rac1 and Cdc42. However, by comparing the impact of dominant-negative Rac1 and Cdc42 mutants, we show that Rac1 is the dominant regulator of cadherin-directed actin assembly and homophilic contact formation. To pursue upstream elements of the Rac1 signaling pathway, we focused on the potential contribution of Tiam1 to cadherin-activated Rac signaling. We found that Tiam1 or the closely-related Tiam2/STEF1 was recruited to cell-cell contacts in an E-cadherin-dependent fashion. Moreover, a dominant-negative Tiam1 mutant perturbed cell spreading on cadherin-coated substrata. However, disruption of Tiam1 activity with dominant-negative mutants or RNA interference did not affect the ability of E-cadherin ligation to activate Rac1. We conclude that Rac1 critically influences cadherin-directed actin assembly as part of a signaling pathway independent of Tiam1. actin cytoskeleton; Cdc42; E-cadherin 相似文献
152.
153.
Nathan W. Ayer Peter H. Tyedmers Nathan L. Pelletier Ulf Sonesson Astrid Scholz 《The International Journal of Life Cycle Assessment》2007,12(7):480-487
Background, Aim and Scope
As Life Cycle Assessment is being increasingly applied to study fisheries and aquaculture systems, the LCA methodology must be adapted to address the unique aspects of these systems. The focus of this methodological paper is the specific allocation problems faced in studying seafood production systems and how they have been addressed to date. 相似文献154.
155.
Demineralised, freeze-dried bone allografts (DFDBA) have been used extensively by dentists in the treatment of periodontal
and periapical osseous defects resulting from inflammatory diseases. Their use in India however, is limited by the availability
of quality allografts and the high cost of imported alternatives. A study was conducted to assess the osteogenic potential
of DFDBA prepared for the first time in India by the Tata Memorial Hospital (TMH) Tissue Bank. The DFDBA was used in the treatment
of osseous defects after removal of periapical lesions associated with devitalised teeth in 10 healthy patients. At the 6-month
recall visit all the patients showed a remarkable decrease in the grades of mobility, and 9 out of the 10 patients showed
radiographic evidence of complete healing of the osseous defects with evidence of normal bony trabaeculae. These findings
indicate that the indigenously prepared DFDBA is a cost effective, biocompatible material with osteogenic potential that can
be used effectively in treating osseous defects of periapical lesions associated with non vital teeth. 相似文献
156.
Elsa Pimienta Julio C Ayala Caridad Rodríguez Astrid Ramos Lieve Van Mellaert Carlos Vallín Jozef Anné 《Microbial cell factories》2007,6(1):20
Background
Streptokinase (SK) is a potent plasminogen activator with widespread clinical use as a thrombolytic agent. It is naturally secreted by several strains of beta-haemolytic streptococci. The low yields obtained in SK production, lack of developed gene transfer methodology and the pathogenesis of its natural host have been the principal reasons to search for a recombinant source for this important therapeutic protein. We report here the expression and secretion of SK by the Gram-positive bacterium Streptomyces lividans. The structural gene encoding SK was fused to the Streptomyces venezuelae CBS762.70 subtilisin inhibitor (vsi) signal sequence or to the Streptomyces lividans xylanase C (xlnC) signal sequence. The native Vsi protein is translocated via the Sec pathway while the native XlnC protein uses the twin-arginine translocation (Tat) pathway. 相似文献157.
Laurens Pauwels Andrés Ritter Jonas Goossens Astrid Nagels Durand Hongxia Liu Yangnan Gu Jan Geerinck Marta Boter Robin Vanden Bossche Rebecca De Clercq Jelle Van Leene Kris Gevaert Geert De Jaeger Roberto Solano Sophia Stone Roger W. Innes Judy Callis Alain Goossens 《Plant physiology》2015,169(2):1405-1417
158.
159.
160.
The study of mutualistic plant and animal networks is an emerging field of ecological research. We reviewed progress in this field over the past 30 years. While earlier studies mostly focused on network structure, stability, and biodiversity maintenance, recent studies have investigated the conservation implications of mutualistic networks, specifically the influence of invasive species and how networks respond to habitat loss. Current research has also focused on evolutionary questions including phylogenetic signal in networks, impact of networks on the coevolution of interacting partners, and network influences on the evolution of interacting species. We outline some directions for future research, particularly the evolution of specialization in mutualistic networks, and provide concrete recommendations for environmental managers. 相似文献