Mosaic signals

Neural mechanisms of communication from pheromones to mosaic signals. In Chemical Signals in Vertebrates, vol. 9, ed. A. Marchlewska-Koj, J. J. Lepri, and D. Miiller-Schwarze, pp. 61-67. New York Kluwer Academic/Plenum. 

Communication by mosaic signals Individual recognition and underlying neural mechanisms. In Chemical Signals in Vertebrates, vol. 10, ed. R. T. Mason, M. P. LeMaster, and D. Miiller-Scliwarze, pp. 269-282. New York Springer. 

Detector mosaic Buffer IC Switch network Signal processing... 

While the fluid mosaic model of membrane stmcture has stood up well to detailed scrutiny, additional features of membrane structure and function are constantly emerging. Two structures of particular current interest, located in surface membranes, are tipid rafts and caveolae. The former are dynamic areas of the exo-plasmic leaflet of the lipid bilayer enriched in cholesterol and sphingolipids they are involved in signal transduction and possibly other processes. Caveolae may derive from lipid rafts. Many if not all of them contain the protein caveolin-1, which may be involved in their formation from rafts. Caveolae are observable by electron microscopy as flask-shaped indentations of the cell membrane. Proteins detected in caveolae include various components of the signal-transduction system (eg, the insutin receptor and some G proteins), the folate receptor, and endothetial nitric oxide synthase (eNOS). Caveolae and lipid rafts are active areas of research, and ideas concerning them and their possible roles in various diseases are rapidly evolving. 

The mechanisms by which the taste (and also the olfactory) system senses chemical compounds is assumed to occur by way of a chemoreceptory system that interacts effectively with a broad, structural variety of stimulant molecules, by means of a receptor epithelium consisting of the mosaic of adjacent, peripheral membranes of many receptor cells, exposed to a medium carrying stimulus molecules. A receptor cell is conveniently and, for our present purpose, sufficiently defined as a cell equipped to interact, according to some mechanism, with stimulus molecules, to convert the effect of this interaction into a signal, and to project this signal into the system. The taste receptor is thus a differentiated, epithelial cell synaptically contact-... 

A cell is enclosed by a lipid bilayer known as the plasma membrane. In Vignette 1.2 in Chapter 1 we discussed an example of a membrane, a complex structure with a mosaic of embedded or adsorbed moieties such as proteins. It is these membranes that protect the intracellular contents from the exterior environment of the cells and regulate the transport of materials into and out of the cells. They can also act as signal transducers and control the electrical excitation in the nervous system by altering the (membrane) permeability to particular ions in response to stimuli. Such electrical activities can propagate over long distances and represent one of the most spectacular of the membrane functions. 

Fig. 7. Diagrams of the schemes for modifying levels of A, alcohol dehydrogenase and B, pyruvate decarboxylase activity and testing for survival of anoxia. In A, constructs contain the 35S promoter of the cauliflower mosaic virus (35S) driving expression of the cotton Adh cDNA in either the sense (Adh) or antisense (hdA) orientation, linked to the 3 termination signal of the nopaline synthase gene (Nos). Alternatively, the expression of cotton Adh cDNA is under control of the pea Adh promoter sequence (pea Adh). In B, either the 35S promoter or the pea Adh promoter is used to drive expression of the maize pyruvate decarboxylase cDNA (Pdc), linked to a Nos 3 termination sequence. Constructs are introduced into cotton via Agrobacterium tumefaciens-mediated infection of cotton. Transformed cotton callus is then assayed for its ability to survive anoxia.

Fig. 1. Schematic representation of Elcd expression cassette. CaMV 35Sp, cauliflower mosaic virus promoter NOS, nopaline synthase transcription termination signal Elcd, catalytic domain of El gene VSPP, soybean vegetative storage protein P leader sequence to target the protein to apoplast (15).

The module further comprises a flat end surface 124 to which a substrate 126 may be bonded. The substrate is of alumina or sapphire and has disposed thereon a mosaic array 3 of electro-optical detectors 4. The detectors are formed by etching or laser cutting of a mercury cadmium telluride layer which has been deposited on the substrate. Each detector is connected at one end 130 to a common reference terminal 132 and at the other end 136 to terminal 134. The substrate further comprises a pattern of through holes 138 and metal dots 140 such that each signal terminal 134 contacts a dot 140. The substrate 126 is aligned on the end surface 124 such that the metal dots 140 in each hole 138 contacts a conductor 114. As a result, each detector 4 is coupled to a pad 118. 

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