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1.
Rac activation by lysophosphatidic acid LPA1 receptors through the guanine nucleotide exchange factor Tiam1 总被引:9,自引:0,他引:9
Van Leeuwen FN Olivo C Grivell S Giepmans BN Collard JG Moolenaar WH 《The Journal of biological chemistry》2003,278(1):400-406
Lysophosphatidic acid (LPA) is a serum-borne phospholipid that activates its own G protein-coupled receptors present in numerous cell types. In addition to stimulating cell proliferation, LPA also induces cytoskeletal changes and promotes cell migration in a RhoA- and Rac-dependent manner. Whereas RhoA is activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors, it is unknown how LPA receptors may signal to Rac. Here we report that the prototypic LPA(1) receptor (previously named Edg2), when expressed in B103 neuroblastoma cells, mediates transient activation of RhoA and robust, prolonged activation of Rac leading to cell spreading, lamellipodia formation, and stimulation of cell migration. LPA-induced Rac activation is inhibited by pertussis toxin and requires phosphoinositide 3-kinase activity. Strikingly, LPA fails to activate Rac in cell types that lack the Rac-specific exchange factor Tiam1; however, enforced expression of Tiam1 restores LPA-induced Rac activation in those cells. Tiam1-deficient cells show enhanced RhoA activation, stress fiber formation, and cell rounding in response to LPA, consistent with Tiam1/Rac counteracting RhoA. We conclude that LPA(1) receptors couple to a G(i)-phosphoinositide 3-kinase-Tiam1 pathway to activate Rac, with consequent suppression of RhoA activity, and thereby stimulate cell spreading and motility. 相似文献
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A comparative evaluation of five typing techniques for determining the diversity of fluorescent pseudomonads 总被引:3,自引:0,他引:3
Five typing methods were evaluated, utilising 63 strains of fluorescent pseudomonads, to assess their usefulness as tools to study the bacterial diversity within this complex group. The methods used were Biolog metabolic profiling, restriction fragment length polymorphism ribotyping, PCR ribotyping, and repetitive element sequence-based PCR (rep-PCR) utilising BOX and enterobacterial repetitive intergenic consensus (ERIC) primers. Cluster analysis of the results clearly demonstrated the considerable homogeneity of Pseudomonas aeruginosa isolates and, conversely, the heterogeneity within the other species, in particular P. putida and P. fluorescens, which need further taxonomic investigation. Biolog metabolic profiling enabled the best differentiation among the species. Rep-PCR proved to be highly discriminatory, more so than the other DNA fingerprinting techniques, demonstrating its suitability for the analysis of highly clonal isolates. RFLP ribotyping, PCR ribotyping, and rep-PCR produced specific clusters of P. aeruginosa isolates, which corresponded to their origins of isolation, hence we recommend these methods for intraspecific typing of bacteria. 相似文献
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Markovich Oshry Zexer Nerya Negin Boaz Zait Yotam Blum Shula Ben-Gal Alon RivkaElbaum Rivka 《Plant and Soil》2022,477(1-2):57-67
Plant and Soil - High and stable plant productivity is a major aim in agricultural research. Silicon fertilization improves yields of various crops under stress. Nonetheless, broad application of... 相似文献
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Highly efficient de novo mutant identification in a Sorghum bicolor TILLING population using the ComSeq approach 下载免费PDF全文
Habte Nida Shula Blum Dina Zielinski Dhruv A. Srivastava Rivka Elbaum Zhanguo Xin Yaniv Erlich Eyal Fridman Noam Shental 《The Plant journal : for cell and molecular biology》2016,86(4):349-359
Screening large populations for carriers of known or de novo rare single nucleotide polymorphisms (SNPs) is required both in Targeting induced local lesions in genomes (TILLING) experiments in plants and in screening of human populations. We previously suggested an approach that combines the mathematical field of compressed sensing with next‐generation sequencing to allow such large‐scale screening. Based on pooled measurements, this method identifies multiple carriers of heterozygous or homozygous rare alleles while using only a small fraction of resources. Its rigorous mathematical foundations allow scalable and robust detection, and provide error correction and resilience to experimental noise. Here we present a large‐scale experimental demonstration of our computational approach, in which we targeted a TILLING population of 1024 Sorghum bicolor lines to detect carriers of de novo SNPs whose frequency was less than 0.1%, using only 48 pools. Subsequent validation confirmed that all detected lines were indeed carriers of the predicted mutations. This novel approach provides a highly cost‐effective and robust tool for biologists and breeders to allow identification of novel alleles and subsequent functional analysis. 相似文献
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We previously reported the presence of both haloalcohol and haloalkanoate dehalogenase activity in the Agrobacterium sp. strain NHG3. The versatile nature of the organism led us to further characterise the genetic basis of these dehalogenation activities. Cloning and sequencing of the haloalcohol dehalogenase and subsequent analysis suggested that it was part of a highly conserved catabolic gene cluster. Characterisation of the haloalkanoate dehalogenase enzyme revealed the presence of two stereospecific enzymes with a narrow substrate range which acted on d -2-chloropropionic and I-2-chloropropionoic acid, respectively. Cloning and sequencing indicated that the two genes were separated by 87 bp of non-coding DNA and were preceded by a putative transporter gene 66 bp upstream of the d-specific enzyme. 相似文献
7.
Richard D. Rasmussen Wallace H. Yokoyama Shula G. Blumenthal Donald E. Bergstrom Boris H. Ruebner 《Analytical biochemistry》1980,101(1):66-74
High-performance liquid chromatography (hplc) has been used to separate and quantificate the dimethyl ester (DME) derivatives of the four biliverdin isomers of the IX series: biliverdin-IXα, -IXβ, -IXγ, and -IXδ. Samples of 0.5 to 10.0 nmol of biliverdin DME were detected quantitatively upon elution by monitoring the absorbance at 375 nm. A technique was developed in which p-bromoacetanilide (Dupont's recommended test compound for their Zorbax column) is used as a marker for biliverdin-IXα DME. To facilitate quantification of biliverdin-IXβ DME, its extinction coefficient was determined. This method has been used to study biliverdin isomers in various biological species. High-resolution NMR (360 MHz) was used to further characterize the isomers. 相似文献
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Recent duplication of the common carp (Cyprinus carpio L.) genome as revealed by analyses of microsatellite loci 总被引:10,自引:0,他引:10
Genome duplications may have played a role in the early stages of vertebrate evolution, near the time of divergence of the lamprey lineage. Additional genome duplication, specifically in ray-finned fish, may have occurred before the divergence of the teleosts. The common carp (Cyprinus carpio) has been considered tetraploid because of its chromosome number (2n = 100) and its high DNA content. We studied variation using 59 microsatellite primer pairs to better understand the ploidy level of the common carp. Based on the number of PCR amplicons per individual, about 60% of these primer pairs are estimated to amplify duplicates. Segregation patterns in families suggested a partially duplicated genome structure and disomic inheritance. This could suggest that the common carp is tetraploid and that polyploidy occurred by hybridization (allotetraploidy). From sequences of microsatellite flanking regions, we estimated the difference per base between pairs of alleles and between pairs of paralogs. The distribution of differences between paralogs had two distinct modes suggesting one whole-genome duplication and a more recent wave of segmental duplications. The genome duplication was estimated to have occurred about 12 MYA, with the segmental duplications occurring between 2.3 and 6.8 MYA. At 12 MYA, this would be one of the most recent genome duplications among vertebrates. Phylogenetic analysis of several cyprinid species suggests an evolutionary model for this tetraploidization, with a role for polyploidization in speciation and diversification. 相似文献
10.
Of critical importance in drug delivery and tissue engineering applications is the degradability of implanted polymeric materials. The use of peptide-derived cross-linkers in hydrogel design is a valuable approach by which polymeric carriers can be endowed with enzymatic degradability in a predictable, "programmable" fashion. The solid-phase synthesis strategy described herein allows for an expeditious, flexible synthesis of bis-acrylamide-derivatized peptides with complex modifications, as exemplified by the incorporation of fluorophore and quencher moieties into a matrix metalloprotease (MMP)-degradable cross-linker. The crude synthetic product was obtained in high yield and purity and purified by standard methods; it was then used directly for polymerization without the need for tedious and often nonchemoselective solution-phase modifications. Functional appendages incorporated for detection provided a direct, quantitative link between enzymatic activity and hydrogel degradation using routine methods for identification of optimal enzyme-specific degradability. 相似文献