Experiments on a bistable chemical reaction in continuously fed thin gel layer reveal new type of spatiotemporal pattern, one which fronts propagate at constant speed until they reach critical separation (typically 0.4 millimeter) and stop. The resulting asymptotic state is highly irregular stationary pattern that contrasts with the regular patterns such as hexagons, squares, stripes have been observed many nonequilibrium systems. are initiated by finite amplitude perturbation rather than...

Quantitative experiments are described on spatio-temporal patterns of coherent chemical signaling activity in populations {\it Dictyostelium discoideum} amoebae. We observe competition between spontaneously firing centers and rotating spiral waves that depends strongly the overall cell density. At low densities, no complete spirals appear chemotactic aggregation is driven by periodic concentric waves, whereas at high densities seen early times nucleate apparently entrained whose cores...

“Green” emission: A novel two-photon fluorescent probe that can detect intracellular free Mg2+ ions at a depth of few hundred micrometers in live tissue was developed. The emission from the Mg2+–probe complex (green) shows little interference association with other metal or cell membrane (blue).

Experiments on a ferrocyanide-iodate-sulfite reaction-diffusion system reveal several different planar spatial patterns: stationary lamellae arising from transverse front instability and interaction; spot patterns that undergo continuous process of growth through replication death overcrowding; waves with repulsive conventional excitable annihilate upon collision. The form in thin gel layer is contact continuously fed stirred reservoir. Lamellae are observed both multistable monostable...

A novel, two-photon probe for the detection of free Mg2+ ions in living cells and live tissues has been developed. The can be excited by 880 nm laser photons, emits strong fluorescence response to ions, easily loaded into cell tissue, shows high photostability, measure ion concentration without interference Ca2+ cells. intracellular dissociation constant (Kdi) determined process is 2.5 mM, which suitable dynamic measurement. In addition, capable imaging endogenous stores at a few hundred...

The living image: efficient two-photon probes AZn1 and AZn2 (see picture for rat brain tissue) show 24- to 52-fold excited fluorescence enhancement in response Zn2+. They can selectively detect intracellular free Zn2+ ions live cells tissues at a depth of 80–150 μm without interference from other metal the membrane-bound probes. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z800929_s.pdf or author. Please note: publisher not...

Move with the groove: Two-photon fluorescent pH probes and a two-photon lysotracker (AL1) can visualize acidic vesicles in live cells living tissue for long period of time without mistargeting photobleaching problems. Using AL1, be tracked real (see picture).

We report a new two-photon fluorescence turn-on probe 6-[(E)-3-oxo-1-dodecenyl]-2-[N-methyl-N-(carboxymethyl)amino]naphthalene (CL2) that is designed specifically for visualizing lipid rafts in living cells and tissues. This emits much brighter excited than non-raft domains allows direct visualization of the live pyramidal neuron layer CA1 region at depth 100−250 μm tissues using microscopy.

Phase synchronization transitions in two different coupled chaotic systems (R\"ossler and Lorentz) are investigated shown to be well described by a reduced model of an overdamped periodically driven nonlinear oscillator with time varying coefficient. In both systems, the phase separation increases $2\ensuremath{\pi}$ jumps below transition. The scaling rules jump near away from transition studied: Near average interval between successive follows...

Starving Dictyostelium amoebae emit pulses of the chemoattractant cAMP that are relayed from cell to as circular and spiral waves. We have recently modeled wave formation in . Our model suggests a secreted protein inhibitor an extracellular phosphodiesterase selects for spirals. Herein we test essential features this prediction by comparing propagation wild type mutants. find mutants rarely form The territory size mutant strains is approximately 50 times smaller than type, mature fruiting...

We demonstrate digital holographic microscopy that, while being based on phase-shifting interferometry, is capable of single-shot measurements. A two-dimensional (2-D) diffraction grating placed in a Fourier plane standard in-line phase microscope generates multiple copies sample image camera sensor. The identical are spatially separated with different overall shifts according to the orders. adjusted by controlling lateral position grating. These then set be multiples π/2. Interferograms...

Field-based polarization measurements are essential for the completeness of information when exploiting complex nature optical responses target objects. Here, we demonstrate digital holographic microscopy quantifying a polarization-sensitive map an object with single-shot measurement. Using image-splitting device generating four different copies image and separate reference beam off-axis configuration enables multi-imaging capability. With use two filters, field images containing object's...

Spatiotemporal wave activities in excitable heart tissues have long been the subject of numerous studies because they underlie different forms cardiac arrhythmias. In particular, understanding dynamics and instabilities spiral waves become very important can cause reentrant tachycardia their subsequent transitions to fibrillation. Although many aspects investigated through experiments model simulations, complex properties are far from well understood. Here, we show that intriguing...

2-Acetyl-6-(dimethylamino)naphthalene-derived two-photon fluorescent Ca2+ probes (ACa1-ACa3) are reported. They can be excited by a 780 nm laser beam, show 23-50-fold enhancement in one- and fluorescence response to Ca2+, emit fourfold stronger than Oregon Green 488 BAPTA-1 upon complexation with selectively detect intracellular free ions live cells living tissues minimum interference from other metal membrane-bound probes. Moreover, these capable of monitoring calcium waves at depth 120-170...

Wave pattern selection between periodic spirals and circular pacemaker waves in excitable media is investigated with numerical simulations a FitzHugh-Nagumo reaction-diffusion model. When have oscillatory tails are more likely dominant over spirals, whereas it opposite when monotonic tails. In both cases coherent state achieved an asymptotic limit single period velocity. The observed wave mechanism seems to underlie the competition signaling activity of Dictyostelium discoideum amoebae population.

The coordinated motion of a cell is fundamental to many important biological processes such as development, wound healing, and phagocytosis. For eukaryotic cells, amoebae or animal the motility based on crawling involves complex set internal biochemical events. A recent study reported very interesting behavior single amoeba: in absence an external cue, free move randomly with noisy, yet, discernible sequence 'run-and-turns' analogous 'run-and-tumbles' swimming bacteria. Interestingly,...

We demonstrate that meandering as well regular spiral waves can form in a well-controlled culture layer of rat ventricle cells and the wave, particular, generate an alternant rhythm. These observations are made possible by newly developed, noninvasive phase contrast macro-optics is simple but highly effective visualizing contractile motion populations cardiac cells.

Recent numerical simulations on two-dimensional model reaction-diffusion systems have revealed unusual spiral waves with complex oscillations and turbulent patterns, both mediated by ``line defects.'' Here we report the observation of such patterns in a laboratory experiment for first time; period-2 period-3 filled tangle line defects are observed their spatiotemporal dynamics elucidated defects. Since generic property periodic media, expected to arise broad class systems.

Lebendiges Abbild: Die effizienten Zweiphotonensonden AZn1 und AZn2 reagieren auf die Bindung von Zn2+ mit einer 24- bis 52fachen Fluoreszenzverstärkung. Sonden können freie Zn2+-Ionen in lebenden Zellen Geweben (im Bild Rattenhirngewebe) 80–150 μm Tiefe selektiv ohne Interferenzen anderer Metallionen der membrangebundenen detektieren. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2008/z800929_s.pdf or from author. Please note:...

Cisplatin was incidentally discovered to suppress cell division and became one of the most successful antitumor drugs. It is therapeutically active upon binding DNA locally kinking it. We demonstrate that after a bimodal modeling, degree platination single molecule can be consistently reliably estimated from elasticity measurements performed with magnetic tweezers. predicted measured for first time two separate persistence lengths kinked at high low tensions. also directly observed strongly...

Abstract The suprachiasmatic nucleus (SCN) is the master clock in mammals governing daily physiological and behavioral rhythms. It composed of thousands cells with their own intrinsic periods varying over a wide range (20–28 h). Despite this heterogeneity, an intact SCN maintains coherent 24 h periodic rhythm through some cell‐to‐cell coupling mechanisms. This study examined how are connected to each other phases organized space by monitoring cytosolic free calcium ion concentration ([Ca 2+...

Standing wave patterns that arise on the surface of ferrofluids by (single frequency) parametric forcing with an ac magnetic field are investigated experimentally. Depending frequency and amplitude forcing, system exhibits various including a superlattice subharmonic rhombuses as well conventional harmonic hexagons squares. The arises in bicritical situation where modes collide. rhombic pattern due to nonmonotonic dispersion relation ferrofluid.