Natural biological memory systems

From OpenWetWare
Jump to: navigation, search

Summary

Nature use different specific mechanisms to write, store, and read memory.Here I plan to make an inventory of these mechanisms, to finally highlight the common motifs and architecture that could successfully be used to build a reliable genetic memory device.

Background

By memory, we intend a mechanism allowing information storage and retrieval.

In general terms, memory in biological systems can be described as the capacity of the system to maintain a state induced by a particular event, even when this causative event has disappeared.

Depending the timeframe during which the state is maintained, we can talk about short- or long-term memory. At least for long-term memory, memory set up implies switching from one stable state to another. Thus, althought the existence of many different types of switches, most of the memory systems can occupy two (bistables) or more (multistables) stable states without intermediary state.

this part to be continued...

Basic classification of memory mechanisms

Genetic

Refers to the information stored in the DNA sequence itself.

  • mutation
  • insertion
    • case of integrases
  • orientation
    • case of invertases
  • recombination
    • Double strand breaks (DSBs) repair
    • Gene conversion(meiosis)
    • crossing-over (meiosis)

Epigenetic

Refers to information stored by others means than DNA sequence itself. An epigenetic change in gene expression can be described as "... a change in the state of expression of a gene that does not involve a mutation,but that is nevertheless inherited in the absecnce of signal (or event) that initiated this change" (Ptashne, 2007).

  • DNA methylation

  • Histones post-translational modifications?

  • proteine structure (prions proteins) url
  • Feedback loops

Different kinds of network motifs can be used to retain the state induced by a stimulus. Positive or auto-positive feedback between signalling proteins is one recurrent motif encountered in natural memory systems.Once activated, the system autostimulates and then maintain the induced state. Systems comprising two genes repressing the expression of each other are also widely encountered.

However, the network wiring motif by itself is not sufficient to make an efficient switch. Various parameters like cooperativity make that a given biological system can exhibits multistability.

Examples

References:

A non exhaustive inventory of nature's strategies to write and maintain memory


Note: would be nice to add a topic on bistability and multistability URL URL URL


Back to Jerome's notebook

Back to Endy genetic memory notebook



Recently Edited Notebook Pages

Extension:DynamicPageList (DPL), version 3.1.1: Warning: No results.

|}