Dataset Information

Coordinated movements prevent jamming in an Emperor penguin huddle.

ABSTRACT: For Emperor penguins (Aptenodytes forsteri), huddling is the key to survival during the Antarctic winter. Penguins in a huddle are packed so tightly that individual movements become impossible, reminiscent of a jamming transition in compacted colloids. It is crucial, however, that the huddle structure is continuously reorganized to give each penguin a chance to spend sufficient time inside the huddle, compared with time spent on the periphery. Here we show that Emperor penguins move collectively in a highly coordinated manner to ensure mobility while at the same time keeping the huddle packed. Every 30-60 seconds, all penguins make small steps that travel as a wave through the entire huddle. Over time, these small movements lead to large-scale reorganization of the huddle. Our data show that the dynamics of penguin huddling is governed by intermittency and approach to kinetic arrest in striking analogy with inert non-equilibrium systems, including soft glasses and colloids.

SUBMITTER: Zitterbart DP

PROVIDER: S-EPMC3106014 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Coordinated movements prevent jamming in an Emperor penguin huddle.

Zitterbart Daniel P DP Wienecke Barbara B Butler James P JP Fabry Ben B

PloS one 20110601 6

For Emperor penguins (Aptenodytes forsteri), huddling is the key to survival during the Antarctic winter. Penguins in a huddle are packed so tightly that individual movements become impossible, reminiscent of a jamming transition in compacted colloids. It is crucial, however, that the huddle structure is continuously reorganized to give each penguin a chance to spend sufficient time inside the huddle, compared with time spent on the periphery. Here we show that Emperor penguins move collectively ...[more]

PMID: 21673816

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Project description:Acid-sensing ion channels (ASICs) are neuronal Na(+)-conducting channels activated by extracellular acidification. ASICs are involved in pain sensation, expression of fear, and neurodegeneration after ischemic stroke. Functional ASICs are composed of three identical or homologous subunits, whose extracellular part has a handlike structure. Currently, it is unclear how protonation of residues in extracellular domains controls ASIC activity. Knowledge of these mechanisms would allow a rational development of drugs acting on ASICs. Protonation may induce conformational changes that control the position of the channel gate. We used voltage-clamp fluorometry with fluorophores attached to residues in different domains of ASIC1a to detect conformational changes. Comparison of the timing of fluorescence and current signals identified residues involved in movements that preceded desensitization and may therefore be associated with channel opening or early steps leading to desensitization. Other residues participated in movements intimately linked to desensitization and recovery from desensitization. Fluorescence signals of all mutants were detected at more alkaline pH than ionic currents. Their midpoint of pH dependence was close to that of steady-state desensitization, whereas the steepness of the pH fluorescence relationship was closer to that of current activation. A sequence of movements was observed upon acidification, and its backward movements during recovery from desensitization occurred in the reverse order, indicating that the individual steps are interdependent. Furthermore, the fluorescence signal of some labeled residues in the finger domain was strongly quenched by a Trp residue in the neighboring ?-ball domain. Upon channel activation, their fluorescence intensity increased, indicating that the finger moved away from the ? ball. This extensive analysis of activity-dependent conformational changes in ASICs sheds new light on the mechanisms by which protonation controls ASIC activity.

Dataset Information

Coordinated movements prevent jamming in an Emperor penguin huddle.

Publications

Coordinated movements prevent jamming in an Emperor penguin huddle.

Similar Datasets

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