Team:Paris Bettencourt/Hardware setup

Light Signalling in Gels

OPTIC MODEL

Introduction

Medusa aims at optically controlling bacteria immobilized in a gel by targetting them with two intersecting lasers. Two questions are important to address to achieve this goal:

How far can a laser go in a gel?

What resolution can the laser achieve?

We present in this page our study of the optical properties of commonly used culture gels. We show that it is possible to obtain a clean light signal even at gel depths greater than 10cm.

Gel Choice

The optical properties of a gel depends on the gel type, its concentration and the nutrient source.

It is best to use a low gel concentration to reduce absorbance.
Alginate Agar Gelrite
Key advantage Solidifies at room temperature
by adding calcium ion
Most ubiquitous microbiology gel Low absorbance
Recommended concentration 1.75-4% 1-1.5% 0.15-0.25%
Melting-Gelling Point NA 0.5%:85-20C
1%:90-35C
0.5%:65-15
1%:100-35C
Key disadvantage Properties depend on calcium ion diffusion
which is hard to control
High absorbance Melts less well than agar
Concentration studied 1% with LB 1% with LB 1% & 0.5% with LB
Table 1: Gel Included in this Study
The optical properties of a gel depends on the gel type, its concentration and the nutrient source.

It is best to use a low gel concentration to reduce absorbance. Conveniently some gels have a higher melting point than solidifying point. This hysteresis phenomenon means that the gel concentration can be lowered and still be kept at in a solid state at 37C by pre-cooling them (to 6-8C) prior to warm incubation.

Alginate gelling is induced by calcium ions which crosslink gelling polymers at room temperature. To get a homogenous gel, calcium ions cannot be mixed with an Alginate solution but must diffuse from an underlying calcium source (1). Since the optical properties of Alginate depends on the amount of crosslinking, they ultimately depend on calcium diffusion which is a difficult parameter to control. It is important to note that keeping the same diffusion conditions (time, temperature, calcium source concentration etc.) is necessary to maintain identical alginate optical properties between experiments.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.

SECOND MODEL

your text
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.

THIRD MODEL

your text
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.
RNA is a light cost nucleotide material in the cell, We aim to recreate RNA agglomerations as formed in mammalian cells with triple repeat disorders, which show liquid phase separation, forming a organelle-like vesicle, where local concentrations of enzymes can be created.


Centre for Research and Interdisciplinarity (CRI)
Faculty of Medicine Cochin Port-Royal, South wing, 2nd floor
Paris Descartes University
24, rue du Faubourg Saint Jacques
75014 Paris, France
bettencourt.igem2017@gmail.com