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Archive for the ‘John Heil’ tag

The Return of Phi C31

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I’ve been so out of the loop with iGEM over the last month. I’ll need to figure out how to get back into the swing of things, probably starting with the post mortem meeting on Tuesday. Generally, since no new maths could be put on the table that actually encompassed the problem well– the brute force approach was kicked into high gear with a few more filters to increase the probability of success.

Call these “System Filters” since they aren’t really based on biologically significant concepts, really just sanity checks that are conceptually consistent with the project (i.e. we’d run out of hard disk space otherwise…). Significantly, Matthew implemented “Blank Stare”, which destroys reactants that exceed a given length (thus preventing them from hogging the CPU looking for less parsimonious solutions). Less significant were Andre’s “Lone Gunman” which deletes arbitrary chromosomes with stochastic efficiency and my “Tag” which prevents chromosomes from cross reacting.

(On second thought, “Tag” IS a “Biological Filter” not a “System Filter” because it removes redundancy by implementing the rule that we only admit bacteria that have exactly one chromosome.)

I should mention that “significance” above isn’t about the triviality of the code, it’s about the amount of anticipated efficiency boon we’d gain from an item’s deployment.

Tomorrow’s post mortem will continue the work I’ve started on our iGEM 2009 Wiki Modelling page… We’ll decide what we want to mention, how close we got to our solution and figure out how to precisely characterize the problem space uncovered by our various attempts.

Additionally, we should probably discuss the relevance of John’s attN site cloning and tests to see if the operators show any sign of degeneracy, and which ones in particular.

Finally, I should mention that Brandon has been working on a C++ port of the whole application we wrote in Python to elucidate how much the virtual machine impacted the performance of our solver– the team is quite divided on this idea with a big half (myself included) thinking that the exponential growth due to the algorithm is the greater factor– Brandon may have some answers for us when it’s up and running.

oGEM: An iGEM Story

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Thursday last week, the Waterloo iGem team had a online conference over Skype with the iGem teams of Toronto and Ottawa. Also present was Andrew Hessel– the seeder of Canadian iGEM teams… It was pretty extensive, so I’ll just discuss the parts that ended up being immediate goals for the Waterloo team.

oGEM Meeting Over Skype

oGEM Meeting Over Skype

The objective is to end up making an Ontario federation in synthetic biology under the iGEM scaffold a reality; we would eventually expand out of iGEM and cover synthetic biology across Canada, but — plan small, think big.

There must also be incentives for being part of such a federation– an obvious answer is a network of distributed services which are greater as oGEM than the sum of its parts.

Plan Small, Think Big

One of the first things we can experiment on is the idea of a social engineering application. This feature is being investigated by the Waterloo team– Arianne has created a mock-up using Elgg. The objective is to allow individuals across oGEM to know what expertise exists in the network, and to contact appropriate users for collaboration or help based on the interests or skills listed by each user.

Sigma is for Summation

Incentive services for oGEM are being tackled by our team. Andre wants to introduce a federated database of strains and cultures (codenamed BioMortar)– whereas iGEM offers clonable biobricks, the issue remains that cellular transformation is not deterministic. It may work some of the time, or most of the time– for some teams, certain bricks just aren’t successfully cloned. This federation would allow the cataloging of living frozen strains in freezers across oGEM and if users are willing, all synthetic open-source strains. Eventually, someone seeking a strain they’ve had issues with would message someone with a working copy as it were, and request it be shipped.


We expect caveats to emerge– first of which is dedication. In our meeting, it is clear that working groups must emerge to take over tasks– working groups that are passionate about their own objectives. I suppose UWiGEM represents two working groups each operating on one of the above steps. Ottawa has volunteered to look at the legal caveats– how oGEM identifies itself as a legal entity as well as its level of permitted activity while still being a part of iGEM and synthetic biology across the nation is all very vague. It’s good that someone has an idea of how to investigate this feature of the problem terrain!

Group Photo

Attending the meeting on the Waterloo side…

oGEM Chat - Waterloo Side

oGEM Chat - Waterloo Side

Left to right in the above photo: Danielle, Andre, John, Leah.

iGEM: Freedom Unhashed

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An iGEM modeling meeting was held yesterday wherein Andre revealed his big plans for switching the team into enduserhood. Unfortunately, I didn’t follow along as well as I could have this time around and can really only document and comment on the bottom line.

We’ve again self-organized into two to three teams based on task. The first team is charged with creating a hashing function which creates a sequence of integrase usable tokens from an integer. The second (and third?) team is responsible for creating a check to ensure that a given product corresponds correctly to a given pair of reactant sequences. Finally, the dangling task of creating an even bigger external harness along with modifications to the present main.py program logic is likely being handled by the latter team.

The Hashing Task is kind of interesting because it essentially calls for unhashing an integer into a meaningful sequence rather than hashing a meaningful sequence into a unique integer. Since the reactant strings can themselves be lexicographically sequenced, then the task quickly becomes an enumeration or counting problem whereupon we find the most efficient way to count through the possible permutations of reactant tokens until we reach the integer that we want. The backward task (what we’re doing) may end up being implemented as the forward task with a sequential search.

The hashing subteam is headed by Jordan, the modeling head from last year and is joined by myself and Wylee– I honestly don’t see this as a task that can’t be completed by one person in a single bout of insanity– so it’s likely that I’ll hop over to Andre’s reactant-product verification team whenever this finishes.

We’ve planned another meeting for Tuesday 5pm next week to pull whatever we have together and to tackle any nascent problems.

Reactant-Product Verification is I think the more straight forward item, at least to explain. It is likely more technically challenging. Basically, we make the reaction go forward, and if the product matches what we wanted, then we favour the persistence of the product. … Err, at least that’s how I understood it… I’ll probably need to pop in and ask about it on Thursday before the big oGEM Skype meeting.

Side note– Oddly, both Shira and John were present at this meeting– it probably means we’re expecting progress 😀

Eddie Ma

July 22nd, 2009 at 5:36 pm