38.Polyunsaturated fatty acids are increasingly produced by microbes which live in low temperature environments and in low temperature and high pressure environments. 39.Membrane proteins are also sensitive to pressure.The piezophilic bacterium Photobacterium profundum species strain SS9 one major protein in its outer membrne at low pressure and another major outer membrane protein at high pressure. 40.The production of these outer membrane proteins is controlled by a transmembrane transcription factor called ToxR.Together with its associated protein ToxS the SS9 ToxR protein senses hydrostatic pressure changes and either turns on one outer membrane protein gene,or stopps blocking the expression of the other outer membrane protein gene.SS9 ToxR also controls the pressure regulation of genes involved in starvation adaptation. 41.Another pressure-regulated cell function is motility (movement from one location to another through a liquid). 42.P.profundum SS9 motility has been examined using a high pressure microscope. 43.Compared to mesophilic bacteria SS9 swims remarkably well at high pressure. In fact for brief periods SS9 can swim at pressures above the known pressure limit for piezophilic life. 44.DNA replication is also sensitive to high pressure. 45.Genetic experiments in P.profundum species strain SS9 indicate that the initiation of DNA replication requires adaptation to high pressure.If a positive regulator of DNA replication is abolished the cells become more pressure-sensitive.If a negative regulator of the initiation of DNA replication is removed the cells display more enhanced growth at high pressure. 46.Finally protein synthesis is also quite sensitive to high pressure. 47.Here is a view of the structure of the ribosome (used for protein synthesis), including its50S and 30S subunits.The image presents a ribosome attached to a messenger RNA molecule.It is in the act of synthesis of a new protein. 1111 38. Polyunsaturated fatty acids are increasingly produced by microbes which live in low temperature environments and in low temperature and high pressure environments. 39. Membrane proteins are also sensitive to pressure. The piezophilic bacterium Photobacterium profundum species strain SS9 one major protein in its outer membrne at low pressure and another major outer membrane protein at high pressure. 40. The production of these outer membrane proteins is controlled by a transmembrane transcription factor called ToxR. Together with its associated protein ToxS the SS9 ToxR protein senses hydrostatic pressure changes and either turns on one outer membrane protein gene, or stopps blocking the expression of the other outer membrane protein gene. SS9 ToxR also controls the pressure regulation of genes involved in starvation adaptation. 41. Another pressure-regulated cell function is motility (movement from one location to another through a liquid). 42. P. profundum SS9 motility has been examined using a high pressure microscope. 43. Compared to mesophilic bacteria SS9 swims remarkably well at high pressure. In fact for brief periods SS9 can swim at pressures above the known pressure limit for piezophilic life. 44. DNA replication is also sensitive to high pressure. 45. Genetic experiments in P. profundum species strain SS9 indicate that the initiation of DNA replication requires adaptation to high pressure. If a positive regulator of DNA replication is abolished the cells become more pressure-sensitive. If a negative regulator of the initiation of DNA replication is removed the cells display more enhanced growth at high pressure. 46.Finally protein synthesis is also quite sensitive to high pressure. 47. Here is a view of the structure of the ribosome (used for protein synthesis), including its50S and 30S subunits. The image presents a ribosome attached to a messenger RNA molecule. It is in the act of synthesis of a new protein