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Related Experiment Video

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Neutron Spin Echo Spectroscopy as a Unique Probe for Lipid Membrane Dynamics and Membrane-Protein Interactions

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Separating intrinsic from extrinsic fluctuations in dynamic biological systems.

Andreas Hilfinger¹, Johan Paulsson

¹Department of Systems Biology, Harvard University, 200 Longwood Avenue, Boston, MA 02115, USA.

Proceedings of the National Academy of Sciences of the United States of America

|July 7, 2011

Summary

Dual-reporter methods can distinguish intrinsic and extrinsic biological noise, but often yield flawed conclusions about intrinsic noise. Rigorous analysis requires careful consideration of system conditions for accurate biological noise assessment.

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Area of Science:

Systems biology
Stochastic processes
Population dynamics

Background:

Biological systems exhibit fluctuations from intrinsic randomness and extrinsic environmental changes.
Analyzing combined noise sources is complex, often leading to simplifying assumptions in studies.
Dual-reporter methods are used to dissect intrinsic and extrinsic noise contributions.

Purpose of the Study:

To mathematically demonstrate how dual-reporter systems can identify intrinsic and extrinsic noise terms.
To compare noise contributions identified by dual-reporter methods with predictions from stochastic models.
To establish a rigorous framework for analyzing fluctuating biological systems.

Main Methods:

Mathematical modeling of biological noise.
Analysis of dual-reporter systems in fluctuating environments.
Comparison of empirical noise measurements with theoretical predictions from stochastic models.

Main Results:

Dual-reporter methods can identify intrinsic and extrinsic noise, but these contributions differ from previous reports.
Extrinsic noise can be rigorously analyzed using models that ignore intrinsic stochasticity for broad system classes.
Intrinsic noise analysis using models ignoring extrinsic stochasticity is only valid under rare biological conditions, potentially leading to flawed conclusions.

Conclusions:

Dual-reporter methods offer insights into biological noise but require careful interpretation, especially for intrinsic noise.
The identified extrinsic noise is robust under broader conditions than intrinsic noise.
A rigorous framework is needed for accurate analysis of noise in fluctuating biological systems.