148 research outputs found
The Biosemiotic Approach in Biology : Theoretical Bases and Applied Models
Biosemiotics is a growing fi eld that investigates semiotic processes in the living realm in an attempt to combine the fi ndings of the biological sciences and semiotics. Semiotic processes are more or less what biologists have typically referred to as â signals, â â codes, âand â information processing âin biosystems, but these processes are here understood under the more general notion of semiosis, that is, the production, action, and interpretation of signs. Thus, biosemiotics can be seen as biology interpreted as a study of living sign systems â which also means that semiosis or sign process can be seen as the very nature of life itself. In other words, biosemiotics is a field of research investigating semiotic processes (meaning, signification, communication, and habit formation in living systems) and the physicochemical preconditions for sign action and interpretation.
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Tripartite phase separation of two signal effectors with vesicles priming B cell responsiveness.
Antibody-mediated immune responses rely on antigen recognition by the B cell antigen receptor (BCR) and the proper engagement of its intracellular signal effector proteins. Src homology (SH) 2 domain-containing leukocyte protein of 65âkDa (SLP65) is the key scaffold protein mediating BCR signaling. In resting B cells, SLP65 colocalizes with Cbl-interacting protein of 85âkDa (CIN85) in cytoplasmic granules whose formation is not fully understood. Here we show that effective B cell activation requires tripartite phase separation of SLP65, CIN85, and lipid vesicles into droplets via vesicle binding of SLP65 and promiscuous interactions between nine SH3 domains of the trimeric CIN85 and the proline-rich motifs (PRMs) of SLP65. Vesicles are clustered and the dynamical structure of SLP65 persists in the droplet phase in vitro. Our results demonstrate that phase separation driven by concerted transient interactions between scaffold proteins and vesicles is a cellular mechanism to concentrate and organize signal transducers
Cloning and Sequencing of Protein Kinase cDNA from Harbor Seal (Phoca vitulina) Lymphocytes
Protein kinases (PKs) play critical roles in signal transduction and
activation of lymphocytes. The identification of PK genes provides a tool for
understanding mechanisms of immunotoxic xenobiotics. As part of a larger study
investigating persistent organic pollutants in the harbor seal and their possible
immunomodulatory actions, we sequenced harbor seal cDNA fragments encoding
PKs. The procedure, using degenerate primers based on conserved motifs of
human protein tyrosine kinases (PTKs), successfully amplified nine phocid PK gene
fragments with high homology to human and rodent orthologs. We identified eight
PTKs and one dual (serine/threonine and tyrosine) kinase. Among these were
several PKs important in early signaling events through the B- and T-cell receptors
(FYN, LYN, ITK and SYK) and a MAP kinase involved in downstream signal
transduction. V-FGR, RET and DDR2 were also expressed. Sequential activation
of protein kinases ultimately induces gene transcription leading to the proliferation
and differentiation of lymphocytes critical to adaptive immunity. PKs are potential
targets of bioactive xenobiotics, including persistent organic pollutants of the marine
environment; characterization of these molecules in the harbor seal provides
a foundation for further research illuminating mechanisms of action of contaminants
speculated to contribute to large-scale
die-offs of marine mammals via immunosuppression
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