The ability to control cell volume is pivotal for cell function. Cell volume perturbation elicits a wide array of signaling events, leading to protective (e.g., cytoskeletal rearrangement) and adaptive (e.g., altered expression of osmolyte transporters and heat shock proteins) measures and, in most cases, activation of volume regulatory osmolyte transport. After acute swelling, cell volume is r...

Anaerobic ammonium-oxidizing (anammox) bacteria are the last major addition to the nitrogen-cycle (N-cycle). Because of the presumed inert nature of ammonium under anoxic conditions, the organisms were deemed to be nonexistent until about 15 years ago. They, however, appear to be present in virtually any anoxic place where fixed nitrogen (ammonium, nitrate, nitrite) is found. In various mar`ine...

Glucose-stimulated insulin secretion consists of a transient first phase followed by a sustained second phase. Diabetes (type II) is associated with abnormalities in this release pattern. Here we review the evidence that biphasic insulin secretion reflects exocytosis of two functional subsets of secretory granules and the implications for diabetes.

The uroepithelium sits at the interface between the urinary space and underlying tissues, where it forms a high-resistance barrier to ion, solute, and water flux, as well as pathogens. However, the uroepithelium is not simply a passive barrier; it can modulate the composition of the urine, and it functions as an integral part of a sensory web in which it receives, amplifies, and transmits infor...

Balaban, Robert S. Modeling mitochondrial function. Am J Physiol Cell Physiol 291: C1107–C1113, 2006. First published September 13, 2006; doi:10.1152/ajpcell.00223.2006.—The mitochondrion represents a unique opportunity to apply mathematical modeling to a complex biological system. Understanding mitochondrial function and control is important since this organelle is critical in energy metabolis...

Atomic force microscopy is an extremely versatile technique, featuring atomic-scale imaging resolution, and also offering the possibility to probe interaction forces down few pN. Recently, this technique has been specialized study between single living cells, one on substrate, a second being adhered cantilever. Cell–cell spectroscopy offers unique tool investigate in fine detail intra-cellular ...

Among the membrane compartments of a cell, vesicles known as "caveolae" have long defied functional characterization. However, since the identification of a family of proteins termed "caveolins", that form and reside in caveolae, a better understanding has emerged. It is now clear that caveolae do not merely play a singular role in the cell, but are pleiotropic in nature-serving to modulate man...

The literature on intracellular signal transduction presents a confusing picture: every regulatory factor appears to be regulated by all signal transduction cascades and to regulate all cell processes. This contrasts with the known exquisite specificity of action of extracellular signals in different cell types in vivo. The confusion of the in vitro literature is shown to arise from several cau...

The fluorescent dyes or cellular autofluorescence can be used in studies of cell structure and in physiological measurements. The confocal microscope collects the information from a welldefined optical section; thus, out of focus fluorescence is eliminated, which results in an increase in contrast, clarity and detection of optical objects. Moreover, stacks of optical sections taken at successiv...

This paper reviews the sequence of events in stimulus-secretion coupling in neurons and paraneurons which can be divided into three main steps: the reception of the stimuli, the conduction of excitation, and the extrusion of messenger substances. One physiological criterion of the paraneuron is that its conductile region is believed to be short enough to transmit the net electrogenesis to the o...