RESUMO
Cell adhesion to extracellular matrix (ECM) is fundamental to many distinct aspects of cell biology, and has been an active topic for label-free biosensors. However, little attention has been paid to study the impact of receptor signaling on the cell adhesion process. We here report the development of resonant waveguide grating biosensor-enabled label-free and fluorescent approaches, and their use for investigating the adhesion of an engineered HEK-293 cell line stably expressing green fluorescent protein (GFP) tagged ß2-adrenergic receptor (ß2-AR) onto distinct surfaces under both ambient and physiological conditions. Results showed that cell adhesion is sensitive to both temperature and ECM coating, and distinct mechanisms govern the cell adhesion process under different conditions. The ß2-AR agonists, but not its antagonists or partial agonists, were found to be capable of triggering signaling during the adhesion process, leading to an increase in the adhesion of the engineered cells onto fibronectin-coated biosensor surfaces. These results suggest that the dual approach presented is useful to investigate the mechanism of cell adhesion, and to identify drug molecules and receptor signaling that interfere with cell adhesion.
RESUMO
A small in-plane external uniaxial pressure has been widely used as an effective method to acquire single domain iron pnictide BaFe2As2, which exhibits twin-domains without uniaxial strain below the tetragonal-to-orthorhombic structural (nematic) transition temperature Ts. Although it is generally assumed that such a pressure will not affect the intrinsic electronic/magnetic properties of the system, it is known to enhance the antiferromagnetic (AF) ordering temperature TN ( < Ts) and create in-plane resistivity anisotropy above Ts. Here we use neutron polarization analysis to show that such a strain on BaFe2As2 also induces a static or quasi-static out-of-plane (c-axis) AF order and its associated critical spin fluctuations near TN/Ts. Therefore, uniaxial pressure necessary to detwin single crystals of BaFe2As2 actually rotates the easy axis of the collinear AF order near TN/Ts, and such effects due to spin-orbit coupling must be taken into account to unveil the intrinsic electronic/magnetic properties of the system.
RESUMO
We report the genome sequence of Theileria parva, an apicomplexan pathogen causing economic losses to smallholder farmers in Africa. The parasite chromosomes exhibit limited conservation of gene synteny with Plasmodium falciparum, and its plastid-like genome represents the first example where all apicoplast genes are encoded on one DNA strand. We tentatively identify proteins that facilitate parasite segregation during host cell cytokinesis and contribute to persistent infection of transformed host cells. Several biosynthetic pathways are incomplete or absent, suggesting substantial metabolic dependence on the host cell. One protein family that may generate parasite antigenic diversity is not telomere-associated.
Assuntos
Genoma de Protozoário , Linfócitos/parasitologia , Proteínas de Protozoários/genética , Theileria parva/genética , Algoritmos , Animais , Antígenos de Protozoários/genética , Bovinos , Proliferação de Células , Cromossomos/genética , Sequência Conservada , Enzimas/genética , Enzimas/metabolismo , Genes de Protozoários , Linfócitos/citologia , Mitocôndrias/metabolismo , Dados de Sequência Molecular , Organelas/genética , Organelas/fisiologia , Plasmodium falciparum/genética , Estrutura Terciária de Proteína , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo , Análise de Sequência de DNA , Sintenia , Telômero/genética , Theileria parva/crescimento & desenvolvimento , Theileria parva/patogenicidade , Theileria parva/fisiologiaRESUMO
The mosquito-borne malaria parasite Plasmodium falciparum kills an estimated 0.7-2.7 million people every year, primarily children in sub-Saharan Africa. Without effective interventions, a variety of factors-including the spread of parasites resistant to antimalarial drugs and the increasing insecticide resistance of mosquitoes-may cause the number of malaria cases to double over the next two decades. To stimulate basic research and facilitate the development of new drugs and vaccines, the genome of Plasmodium falciparum clone 3D7 has been sequenced using a chromosome-by-chromosome shotgun strategy. We report here the nucleotide sequences of chromosomes 10, 11 and 14, and a re-analysis of the chromosome 2 sequence. These chromosomes represent about 35% of the 23-megabase P. falciparum genome.