Memory in bacteria and phage

Whenever the state of a biological system is not determined solely by present conditions but depends on its past history, we can say that the system has memory. Bacteria and bacteriophage use a variety of memory mechanisms, some of which seem to convey adaptive value. A genetic type of heritable mem...

Full description

Saved in:
Bibliographic Details
Published in:BioEssays 2002-06, Vol.24 (6), p.512-518
Main Authors: Casadesús, Josep, D'Ari, Richard
Format: Article
Language:English
Subjects:
Bacteria - genetics
Bacteriophages - genetics
Bacteriophages - metabolism
Bacteriophages - physiology
Circadian Rhythm
DNA - genetics
DNA Methylation
Lac Operon
Models, Genetic
Temperature
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Whenever the state of a biological system is not determined solely by present conditions but depends on its past history, we can say that the system has memory. Bacteria and bacteriophage use a variety of memory mechanisms, some of which seem to convey adaptive value. A genetic type of heritable memory is the programmed inversion of specific DNA sequences, which causes switching between alternative patterns of gene expression. Heritable memory can also be based on epigenetic circuits, in which a system with two possible steady states is locked in one or the other state by a positive feedback loop. Epigenetic states have been observed in a variety of cellular processes, and are maintained by diverse mechanisms. Some of these involve alternative DNA methylation patterns that are stably transmitted to daughter molecules and can affect DNA–protein interactions (e.g., gene transcription). Other mechanisms exploit autocatalytic loops whereby proteins establish the proper conditions for their continued synthesis. Template polymers other than nucleic acids (e.g., components of the cell wall) may also propagate epigenetic states. Non‐heritable memory is exemplified by parasitic organisms that bear a signature of their previous host, such as host‐controlled modification of phage DNA or porin hitchhiking in predatory bacteria. The heterogeneous nature of the examples known may be indicative of widespread occurrence of memory mechanisms in bacteria and phage. However, the actual extent, variety and potential selective value of prokaryotic memory devices remain open questions, still to be addressed experimentally. BioEssays 24:512–518, 2002. © 2002 Wiley Periodicals, Inc.
ISSN:0265-9247
1521-1878
DOI:10.1002/bies.10102