Wayne Rasband of NIH has created ImageJ, an open source Java-written program that is now at version 1.31 and is used for many imaging applications, including those that that span the gamut from skin analysis to neuroscience. ImageJ is in the public domain and runs on any operating system (OS). ImageJ is easy to use and can do many imaging manipulations. A very large and knowledgeable group makes up the user community for ImageJ. Topics covered are imaging abilities; cross platform; image formats support as of June 2004; extensions, including macros and plug-ins; and imaging library. NIH reports tens of thousands of downloads at a rate of about 24,000 per month currently. ImageJ can read most of the widely used and significant formats used in biomedical images. Manipulations supported are read/write of image files and operations on separate pixels, image regions, entire images, and volumes (stacks in ImageJ). Basic operations supported include convolution, edge detection, Fourier transform, histogram and particle analyses, editing and color manipulation, and more advanced operations, as well as visualization. For assistance in using ImageJ, users e-mail each other, and the user base is highly knowledgeable and will answer requests on the mailing list. A thorough manual with many examples and illustrations has been written by Tony Collins of the Wright Cell Imaging Facility at Toronto Western Research Institute and is available, along with other listed resources, via the Web.

/pdf/image-processing-with-imagej-2nw6tuidbb.pdf

Image processing with ImageJ

Capsaicin, the main pungent ingredient in 'hot' chilli peppers, elicits a sensation of burning pain by selectively activating sensory neurons that convey information about noxious stimuli to the central nervous system We have used an expression cloning strategy based on calcium influx to isolate a functional cDNA encoding a capsaicin receptor from sensory neurons This receptor is a non-selective cation channel that is structurally related to members of the TRP family of ion channels The cloned capsaicin receptor is also activated by increases in temperature in the noxious range, suggesting that it functions as a transducer of painful thermal stimuli in vivo

/pdf/the-capsaicin-receptor-a-heat-activated-ion-channel-in-the-57mhjl9hkd.pdf

The capsaicin receptor: a heat-activated ion channel in the pain pathway

Protein kinase C has a crucial role in signal transduction for a variety of biologically active substances which activate cellular functions and proliferation. When cells are stimulated, protein kinase C is transiently activated by diacylglycerol which is produced in the membrane during the signal-induced turnover of inositol phospholipids. Tumour-promoting phorbol esters, when intercalated into the cell membrane, may substitute for diacylglycerol and permanently activate protein kinase C. The enzyme probably serves as a receptor for the tumour promoters. Further exploration of the roles of this enzyme may provide clues for understanding the mechanism of cell growth and differentiation.

The role of protein kinase C in cell surface signal transduction and tumour promotion

Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals. It operates through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle. This family of intracellular calcium channels displays the regenerative process of calcium-induced calcium release responsible for the complex spatiotemporal patterns of calcium waves and oscillations. Such a dynamic signalling pathway controls many cellular processes, including fertilization, cell growth, transformation, secretion, smooth muscle contraction, sensory perception and neuronal signalling.

Inositol trisphosphate and calcium signalling

There has recently been rapid progress in understanding receptors that generate intracellular signals from inositol lipids. One of these lipids, phosphatidylinositol 4,5-bisphosphate, is hydrolysed to diacylglycerol and inositol trisphosphate as part of a signal transduction mechanism for controlling a variety of cellular processes including secretion, metabolism, phototransduction and cell proliferation. Diacylglycerol operates within the plane of the membrane to activate protein kinase C, whereas inositol trisphosphate is released into the cytoplasm to function as a second messenger for mobilizing intracellular calcium.

Inositol trisphosphate, a novel second messenger in cellular signal transduction.

The salivary glands of the blowfly (Calliphora erythrocephala) are long thin tubes consisting of a single layer of homogeneous cells that secrete iso-osmotic KCI when stimulated by 5-hydroxytryptamine (Berridge, 1975). Cyclic AMP formation is accelerated by 5-hydroxytryptamine and the addition of cyclic AMP mimicks the stimulation of fluid secretion, but not the increase in transepithelial Caz+ flux owing to 5-hydroxytryptamine. 5-Hydroxytryptamine appears to independently accelerate CaZ+ entry and cyclic AMP accumulation. The increase in Ca2+ entry results in elevated anion movement, whereas cyclic AMP stimulates a potassium pump, which results in fluid secretion (Berridge, 1975). Michell et al. (1977) suggested that the breakdown of phosphatidylinositol induced by hormone-receptor complexes in a wide variety of cells is involved in the gating of CaZ+ entry into cells. The present studies were designed to determine whether an increase in phosphatidylinositol hydrolysis owing to 5-hydroxytryptamine is observed in salivary glands. In this study we examined the effects of 5-hydroxytryptamine on the breakdown of phospholipids that had been prelabelled for several hours with either [32P]P, or my0-[2-~H]inositol. In the presence of 5-hydroxytryptamine there was a preferential increase in the hydrolysis of phosphatidylinositol without any increase in the breakdown of phosphatidylcholine or phosphatidylethanolamine. Unlike [32P]Pi, which labels a wide variety of substances, the use of my0-[2-~H]inositol results in a selective labelling of phosphatidylinositol. In glands washed for 30min after a 2h incubation with 5-20~~rny0-[2-~H]inositol more than 94% of the label present in the gland was in the form of phosphatidylinositol. Of the small amount of 3H present in water-soluble compounds 50 % was inositol 1 : 2-cyclic phosphate, 13 % as inositol, 28 % as glycerophosphoinositol and 9% as inositol 1-phosphate. The addition of 5-hydroxytryptamine to salivary glands in which phosphatidylinositol had been labelled by prior incubation with [3H]inositol resulted in an increase in the intracellular accumulation of inositol phosphates within 30s after the addition of hormone, which was followed by a release of labelled inositol to the medium. We could detect no release of label as any product other than inositol. 5-Hydroxytryptamine stimulated the release of inositol to both the medium and the saliva and the effect was sustained as long as the hormone was present. Low concentrations of 5-hydroxytryptamine, which stimulate fluid secretion submaximally, also stimulated phosphatidylinositol breakdown. It was not possible to find a concentration of hormone that stimulated fluid secretion without also increasing phosphatidylinositol breakdown. However, fluid secretion was maximally stimulated by 0.01 ~~-5-hydroxytryptamine, whereas higher concentrations gave further increases in phosphatidylinositol breakdown and CaZ+ flux. Michell et al. (1976) suggested that this indicates a tight and rather direct coupling between the binding of hormone to receptors and the increase in phosphatidylinositol labelling. Similar dose-response curves are observed for the hormonal activation of adenylate cyclase in membrane preparations. The addition of 3-isobutyl-1 -methylxanthine (which presumably potentiates the effect of 5-hydroxytryptamine on cyclic AMP) increased the fluid secretion owing to 1 n~-5-hydroxytryptamine without affecting phosphatidylinositol breakdown. Cyclic AMP also increases fluid secretion, but did not affect phosphatidylinositol hydrolysis or Ca2+ flux in regular buffer. In buffer containing 40n~-K+ it was possible to observe an increase in CaZ+ flux owing to cyclic AMP, but this was not accompanied by any appreciable increase in inositol release to the medium.

Relationship Between 5-Hydroxytryptamine Activation of Phosphatidylinositol Hydrolysis and Calcium-Ion Entry in Calliphora Salivary Glands

The function and efficiency of cell signalling pathways are very dependent on their organization both in space and time. With regard to spatial organization, signalling components are highly organized with respect to their cellular location and how they transmit information from one region of the cell to another. This spatial organization of signalling pathways depends on the molecular interactions that occur between signalling components that use signal transduction domains to construct signalling pathways. Very often, the components responsible for information transfer mechanisms are held in place by being attached to scaffolding proteins to form macromolecular signalling complexes. Sometimes these macromolecular complexes can be organized further by being localized to specific regions of the cell, as found in lipid rafts and caveolae or in the T-tubule regions of skeletal and cardiac cells.

http://www.biochemj.org/csb/csb/006/006.pdf

Spatial and Temporal Aspects of Signalling

Calcium signalling in health and disease

Discovery of the InsP3-Ca2+ pathway. A personal reflection.

Development encompasses the programme of events that begins with fertilization and culminates in complex multicellular organisms like ourselves. Every cell in the adult organism has a distinct life history (Module 8: Figure cellular life history) that can be traced back to the process of maturation that is responsible for the formation of the two gametes that then fuse during fertilization to form the zygote. Fertilization provides a potent mitogenic stimulus, and the zygote enters the cell cycle repeatedly and is rapidly transformed into a multicellular embryo. As development proceeds and the number of cells in the embryo increases, groups of cells are progressively apportioned distinct fates through a process of cell specification. During the final process of cell differentiation, each cell begins to express its unique specialized cell function that enables it to contribute to the operation of different organ systems. This process of differentiation is associated with the cessation of growth, which may be either permanent (e.g. nerves and muscle) or temporary (e.g. lymphocytes, fibroblasts, liver cells, salivary glands, endothelial cells and smooth muscle). In the latter case, the cells that have their growth arrested temporarily retain the ability to return to the cell cycle when stimulated with the appropriate growth factor. Finally, cells die and this can occur either through some catastrophic event, such as necrosis, or through a more controlled programme of cell death known as apoptosis. The typical life history of a cell thus comprises a series of processes:
 Maturation–the formation of mature gametes (spermatozoa and oocytes). Fertilization–the fusion of gametes and the initiation of development. Cell proliferation–rapid rounds of cell growth and cell division. Cell specification–cell determination and pattern formation. Differentiation–the formation of specialized cells.

http://csb.portlandpresspublishing.com/content/ppcellsigbio/6/csb0001008.full.pdf

Michael J. Berridge

Papers

Relationship Between 5-Hydroxytryptamine Activation of Phosphatidylinositol Hydrolysis and Calcium-Ion Entry in Calliphora Salivary Glands

Spatial and Temporal Aspects of Signalling

Calcium signalling in health and disease

Discovery of the InsP3-Ca2+ pathway. A personal reflection.

Cell Signalling Biology: Module 8 - Development