Revision as of 10:59, 20 August 2012

Module 4: Buoyancy

Description

The Buoyancy module is key to both the Degradation and the Aggregation systems. Buoyancy is required to position our bacteria in the water column, and also enables them to buoy the plastic aggregates.

This module requires driving the expression of a gas vesicle gene cluster. Gas vesicles are formed within the cell, and are hollow spaces surrounding by a wall of hydrophobic protein. These gas vesicles are permeable to gases, which diffuse into the gas vesicles, increasing its partial pressure, thereby increasing buoyancy.

The Buoyancy system is subject to the control of a glucose-repressible promoter, PcstA (BBa_K118011). As a starvation promoter, production of gas vesicles will be limited in high cell nutrient environments, but increase as carbon sources become scarce. This gives us a gradient of activation which allows us to control the transcription of gas vesicle genes in different conditions. In our project, we expect this to occur as cells sink to greater depths in the ocean, thereby up regulating buoyancy as resources decrease, buoying our cells back to the targeted ocean surface.

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 == Description==
-The '''Buoyancy Module''' is key to both the degradation and the island formation systems. Buoyancy is required to '''position''' our bacteria in the water column,   and also to enable them to buoy the plastic '''aggregates''' (Module 2).
+The '''Buoyancy module''' is key to both the Degradation and the Aggregation systems. Buoyancy is required to '''position''' our bacteria in the water column, and also enables them to buoy the plastic '''aggregates'''.
-This module requires driving the expression of a '''cluster of gas vesicle genes'''. Gas vesicles are formed within the cell, and are hollow spaces surrounding by a wall of '''hydrophobic''' protein. These gas vesicles are '''permeable''' to gases, which enter and '''inflate''' the vesicles to increase buoyancy.  The gas vesicle system is driven by a '''constitutive''' Heat Shock Promoter BBa k338001 to ensure a constant drive for buoyancy.
+This module requires driving the expression of a '''gas vesicle gene cluster'''. Gas vesicles are formed within the cell, and are hollow spaces surrounding by a wall of '''hydrophobic''' protein. These gas vesicles are '''permeable''' to gases, which diffuse into the gas vesicles, increasing its '''partial pressure''', thereby increasing buoyancy.
-While the promoter is constitutive, there is a '''gradient''' of activation which allows us to control the transcription of gas vesicle genes at different '''depths'''.  The heat shock promoter in our system is '''activated''' in response to '''increases in ambient temperature'''. However we want to couple '''increases''' in temperature this to '''down regulation''' of Gas Vesicle formation, and so we will introduce a '''repressor''' between the Heat Shock Promoter and the Gas Vesicle cluster.  Activation of Heat Shock Promoter, triggers expression of the repressor protein '''tetR''', which binds and repressors the promoter '''p(TetR)'''.  p(TetR) is the promoter driving '''constitutive''' gas vesicle formation, and so activation of the repressor system down regulates gas vesicle formation.
+The Buoyancy system is subject to the control of a '''glucose-repressible''' promoter, '''PcstA (BBa_K118011)'''. As a '''starvation''' promoter, production of gas vesicles will be limited in '''high cell nutrient''' environments, but increase as carbon sources become scarce. This gives us a '''gradient''' of activation which allows us to control the transcription of gas vesicle genes in different conditions. In our project, we expect this to occur as cells sink to greater depths in the ocean, thereby up regulating buoyancy as resources decrease, buoying our cells back to the targeted ocean surface.
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Team:University College London/Module 4

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Revision as of 10:59, 20 August 2012

Module 4: Buoyancy

Description