Muscular expressions: profiling genes in complex tissues

Gene-expression profiling has yielded important information about simple systems, but complex tissues have not yet been widely profiled. Four recent studies of mammalian skeletal muscles have added to the catalogs of their gene expression differences, but have yet to lead to better understanding of the molecular processes underlying their physiological differences

Intermediate filament-co-localized molecules with myosin heavy chain epitopes define distinct cellular domains in hair follicles and epidermis

BACKGROUND: Proteins linking intermediate filaments to other cytoskeletal components have important functions in maintaining tissue integrity and cell shape. RESULTS: We found a set of monoclonal antibodies raised against specific human sarcomeric myosin heavy chain (MyHC) isoforms labels cells in distinct regions of the mammalian epidermis. The antigens co-localize with intermediate filament-containing structures. A slow MyHC-related antigen is punctate on the cell surface and co-localizes with desmoplakin at desmosomal junctions of all suprabasal epidermal layers from rat fœtal day 16 onwards, in the root sheath of the hair follicle and in intercalated disks of cardiomyocytes. A fast MyHC-related antigen occurs in cytoplasmic filaments in a subset of basal cells of skin epidermis and bulb, but not neck, of hair follicles. A fast IIA MyHC-related antigen labels filaments of a single layer of cells in hair bulb. This 230 000 M(r )antigen co-purifies with keratin. No obvious candidate for any of the antigens appears in the literature. CONCLUSIONS: We describe a set of molecules that co-localize with intermediate filament in specific cell subsets in epithelial tissues. These antigens presumably influence intermediate filament structure or function

Self-organization of structures and networks from merging and small-scale fluctuations

We discuss merging-and-creation as a self-organizing process for scale-free topologies in networks. Three power-law classes characterized by the power-law exponents 3/2, 2 and 5/2 are identified and the process is generalized to networks. In the network context the merging can be viewed as a consequence of optimization related to more efficient signaling.Comment: Physica A: Statistical Mechanics and its Applications, In Pres