Asymmetry and inequity in the inheritance of a bacterial adhesive
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Lizenz | CC-Namensnennung 3.0 Unported: Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen. | |
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51
00:00
ElementarteilchenphysikGleitlagerVideotechnik
00:08
Puma <Panzer>Computeranimation
00:13
TissueMatrize <Umformen>Temperaturabhängiger WiderstandHandbuchbindereiVorlesung/KonferenzBesprechung/Interview
00:38
TheodolitMatrize <Umformen>NiederspannungsnetzElektronisches BauelementSatz <Drucktechnik>WarmumformenZelle <Mikroelektronik>GleitlagerFaraday-EffektAngeregter ZustandSchaft <Werkzeug>Vorlesung/KonferenzBesprechung/Interview
01:26
Satz <Drucktechnik>Vorlesung/Konferenz
01:30
AnstellwinkelSatz <Drucktechnik>Computeranimation
01:41
FeldeffekttransistorRegelstabTonnenlegerComputeranimationBesprechung/Interview
02:13
NiederspannungsnetzZelle <Mikroelektronik>Computeranimation
02:26
BeschichtenSatz <Drucktechnik>Zelle <Mikroelektronik>
02:35
Zelle <Mikroelektronik>Computeranimation
02:43
NiederspannungsnetzDiagrammFlussdiagramm
02:48
NiederspannungsnetzDiagramm
03:06
SonnensystemSchnittmusterPatrone <Munition>Angeregter ZustandWeltraumTheodolitGrundfrequenzAbwrackwerftSchlauchkupplungZelle <Mikroelektronik>SternsystemHobelPlanetVorlesung/KonferenzBesprechung/Interview
04:01
Computeranimation
Transkript: Englisch(automatisch erzeugt)
00:13
Biofilms are communities of interacting bacteria that are bound to each other and often to a solid surface by a matrix of polymers that the bacteria produce.
00:23
In biofilms, bacteria resist antibiotic treatment and the immune system, and they cause infections in tissues and on medical devices that can often only be cured by transplant amputation or surgery to remove the device. Biofilms start when single cells attach to a surface
00:42
stuck down by the same types of polymers that will later be important components of the matrix. Then the bacteria divide and proliferate so that the surface-bound population increases. Attachment to a surface also signals bacteria to change the way their genes are expressed to make the transition from the free-swimming state,
01:02
called the planktonic state, to the biofilm state. Here we look at an important human pathogen named Pseudomonas aeruginosa to find out how this bacterium controls the distribution of sticky polymer on the surfaces of single bacterial cells and how the inheritance of sticky polymer propagates
01:20
from parent cells to daughter cells. In work we published in the journal Soft Matter in 2013, we showed that bacteria that make two types of polymers, named PSL and PEL, spend almost all their time lying flat on a surface. Bacteria that make only one type of polymer, PSL, spend a lot of time attached to only one end,
01:41
so they're tilting up off the surface at an angle. Here we show that bacteria that make only PSL tend to have PSL concentrated at one of their ends, but bacteria that make both PSL and PEL tend to have PSL distributed more evenly over their rod-shaped bodies. Because PSL is very sticky to the surface,
02:01
these bacteria will be much more sticky at the end with PSL and less sticky at the other end. This is probably the reason these bacteria spend a lot of time tilting up off the surface, attached to their one sticky end. These bacteria proliferate by growing longer and longer and then dividing across the middle. So if a parent cell has an uneven distribution
02:22
of sticky polymer along its surface, its daughter should inherit different amounts of sticky polymer coating their surfaces. That's the inequity in our title. We see this type of epigenetic inheritance for both daughters and granddaughters. A cell is more likely to tip up off the surface if it inherited less sticky polymer
02:41
from its parent and grandparent. And it's more likely to lie down flat on the surface, strongly attached, if it inherited more sticky polymer. More broadly and speculatively, our results suggest that evolution may have acted to regulate symmetry, both of how bacteria attach to the surface and how the sticky PSL polymer is inherited
03:03
as a population propagates. If so, this suggests that symmetry is important and adaptive for this species of bacterium. One possible reason why might be that tighter coupling to the surface helps the bacteria sense the surface more strongly and make a better transition
03:21
from the free-swimming planktonic state with its associated patterns of gene expression to the biofilm state, which has very different patterns of gene expression. Questions of symmetry and symmetry breaking are pervasive themes in fundamental physics. For example, why is there more matter than anti-matter in the universe? Why is the matter distributed lumpily in the universe
03:42
to give us stars and planets and galaxies? But symmetry is much more rarely seen as a theme in biological physics. Our study illustrates a case of biophysical symmetry and symmetry breaking for bacterial cells and shows how physical concepts of symmetry breaking can give new insight into bacterial biology.