Chiba
From 2007.igem.org
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Introduction | Project Design ( 1.Sticky Hands | 2.Communication | 3.Size Control ) | Making Marimos | Our Goal || Team Members | メンバ連絡簿 |
Introduction
Chiba University iGEM07 team's project is to make a Marimo-ish gathering of bacteria. Marimo is a green spherical shaped algae, which is a popular living organism in Japan as a National Treasure. We borrowed the name Marimo because of its name publicity (maybe only in Japan, which we didn't notice until recently) and their marvelous velvet which charmed us so much. Our motivations for making Marimo bacteria is as follows.
Why Make a "Marimo"?
Making 3D colonies- for next generation (lazier) molecular biologists
For years microbiologists have been using agar plates to isolate cells from each other. By spreading the diluted cells on a solid surface, we can make "colonies", dome-shaped gathering of genetically identical cells. Although convenient, this is only two-dimentional. What if we can create three dimentional (spherical) colonies with controlled/ defined size? Thus we can eliminate the plating process that everybody hates. Combined with the microfluidics devices, we might be able to pick, isolate, count, or innoculate each of the floating yet independent colonies to conduct routine works in future molecular biology. Crazy thought? Well, that is exactly what our advisors say.
Toward the control the population size of the bacteria community
Even in the bacteria community, sometimes they need to do the population control. This is especially so when we think about the chemical production using bacteria robots.
Besides the above illogical/ unjustified reasons, we think this project leads to the behavior control of the bacterial comunity. Lots of challenge in the project including diffusion control of small/ large molecules, chemical production/ degradation balancing,.....
Backgrounds
Marimo?
Marimo is known as a spherical shaped algae which could be found, for example, in the Lake Akan in Hokkaido, Japan. The Lake Akan's Marimo is defined as a Natural Tresure of the country, because of its beautiful velvet and its sphrerical shape.
Actually, the name "marimo" indicates the algae filament, not the sphere. The sphere shape is one of the three growth forms of the aggregated marimo fillaments. Another growth form lives as free-floating fillaments as small tufts of unattached filaments that frequently form a carpet on the muddy lake bottom. The third is epilithic (growing on rocks). Marimos are found in some of the lakes in Japan and other countries, but the beautiful spherical shaped marimos are only known in Iceland, Estonia and Japan.
How Marimos are Made
Natural Marimos
Spherical marimos are formed through the growth of a core which is a fragment of ancestral marimos. So when you watch the cross section of the spherical marimo, you do not recognize a core-shell structure in it. How about the most ancestral marimos? It is expected that the most ancestral marimos had a core made of inorganic materials such as cray particles or sand solids.
Artificial Marimos
Marimos are a popular "pet" in Japan. Well, you can't keep the National Tresure as a pet, so they house the artificial one instead. Although the mechanism of how the spherical marimo are made is not known in detail, the alternative method of making marimo have been invented from about 30 years ago by many Japanese scientist/botanist/marimoist.
The well-known method is as follows:
However, there is a insurmountable barrier in these method: when divided in the middle, the artificial marimo could be found that they have a lack of the radial pattern.
しかし人工的まりも作製法にはやはり越えられない壁があった：半分に切開してみると，内部はfillamentの断片が雑然と集合して球の中心まで詰まっている．これに対して自然の球形毬藻では，fillamentが中心から放射状に配列し，さらに多くの場合，球の中心に近づく程，糸状態の密度が疎になって，しばしば中心は空虚な隙間になっている．
References:
- 阪井與志雄，マリモの科学，北海道大学図書刊行会, 1991 (Yoshio Sakai, Marimo no Kagaku（"The Science of Marimo"))
- 中沢信午，マリモはなぜ丸い その生態と形態，中公新書，1989 (Shingo Nakazawa, Marimo wa naze marui ("Why marimos are spherical"))
