Listeria monocytogenes secretes several proteins that have been shown to contribute to virulence. Among these is listeriolysin O (LLO), a pore-forming hemolysin that is absolutely required for virulence. Two other virulence factors are phospholipases: a phosphatidylinositol-specific phospholipase C (PI-PLC [plcA]) and a broad-range PLC (plcB). Although mutations in plcA or plcB resulted in smal...

Chitwood, Raymond A. and David B. Jaffe. Calcium-dependent properties of interneurons, such as the expression of SFA, spike-frequency accommodation in hippocampal CA3 nonpyramicould therefore have significant effects on an inhibitory neudal neurons. J. Neurophysiol. 80: 983–988, 1998. Interneurons of ral network’s properties. For example, inconsistent synchrothe hippocampal formation are tradit...

Timing-dependent long-term potentiation (t-LTP) is induced when synaptic activity is immediately followed by one or more back-propagating action potentials (bAPs) in the postsynaptic cell. As a mechanistic explanation, it has been proposed that the bAP removes the Mg2+ block of synaptic NMDA receptors, allowing for rapid Ca2+ entry at the active synapse. Recent experimental studies suggest that...

ER for tiny calcium domains iny microdomains of mitosis-driving calcium signals are created by the ER, as shown by Parry et al. on page 47. Although these calcium spikes were suspected to exist—based on findings that blocking calcium signals prevents mitosis in sea urchins—they have often eluded visualization. Parry et al. were able to detect the calcium spikes by using fly embryos, in which th...

Serotonergic neurons of the dorsal raphe nucleus, with their extensive innervation of limbic and higher brain regions and interactions with the endocrine system have important modulatory or regulatory effects on many cognitive, emotional and physiological processes. They have been strongly implicated in responses to stress and in the occurrence of major depressive disorder and other pyschiatric...

Calcium (Ca2+)is an ubiquitous intracellular messenger which regulates cellular processes, such as secretion, contraction, and cell proliferation. A number of different cell types respond to hormonal stimuli with periodic oscillations of the intracellular free calcium concentration ([Ca2+]i). These Ca2+ signals are often organized in complex temporal and spatial patterns even under conditions o...

Neural activity can be captured by state-of-the-art optical imaging methods although the analysis of the resulting data sets is often manual and not standardized. Therefore, laboratories using large-scale calcium imaging eagerly await software toolboxes that can automate the process of identifying cells and inferring spikes. An algorithm proposed and implemented in a recent paper by Mukamel et ...

Dopamine (10 to 50 microM) modulates in two different ways the duration of the Ca2+-dependent action potential recorded in the cell body of identified neurons of the snail Helix aspersa. In some neurons (cells E13 and F1) dopamine increases the amplitude of their Ca2+-dependent spike plateau by decreasing the S-current (Klein, M., J.S. Camardo, and E. R. Kandel (1982) Proc. Natl. Acad. Sci. U.S...

Deprivation of external calcium causes sudden potentiation of the twitch response of single muscle fibers. The potentiation was 64 +/- 8%. Potentiation is simultaneous with membrane depolarization occurring after Ca(++) removal. This depolarization amounted to 9 +/- 2 mv. Ca(++) removal also alters the action potential. 3 min after calcium withdrawal, action potential amplitude fell by 36 +/- 3...