Tuesday, May 20, 2008

Finch 3: Defining the Experimental Information

In today's genetic analysis laboratory, multiple instruments are used to collect a variety of data ranging from DNA sequences to individual values that measure DNA (or RNA) hybridization, nucleotide incorporations, or other binding events. Next Gen sequencing adds to this complexity and offers additional challenges with the amount of data that can be produced for a given experiment.

In the last post, I defined basic requirements for a complete laboratory and data management system in the context of setting up a Next Gen sequencing lab. To review, I stated that laboratory workflow systems need to perform the following basic functions:
  1. Allow you set up different interfaces to collect experimental information
  2. Assign specific workflows to experiments
  3. Track the workflow steps in the laboratory
  4. Prepare samples for data collection runs
  5. Link data from the runs back to the original samples
  6. Process data according to the needs of the experiment
I also added that if you operate a core lab, you'll want to bill for your services and get paid.

In this post I'm going to focus on the first step, collecting experimental information. For this exercise let's say we work in a lab that has:
  • One Illumina Solexa Genome Analyzer
  • One Applied Biosystems SOLiD System
  • One Illumina Bead Array station
  • Two Applied Biosystems 3730 Genetic Analyzers, used for both sequencing and fragment analysis

This image shows our laboratory home page. We run our lab as a service lab. For each data collection platform we need to collect different kinds of sample information. One kind of information is the sample container. Our customer's samples will be sent the lab in many different kinds of containers depending on the kind of experiment. Next Gen sequencing platforms like SOLiD, Solexa, and 454 are low throughput with respect to sample preparation, so samples will be sent to us in tubes. Instruments like the Bead Array and 3730 DNA sequencing instrument, usually involve sets of samples in 96 or 384 well plates. In some cases, samples start in tubes and end up in plates, so you'll need to determine which procedures use tubes and which use plates and how the samples will enter the lab.

Once the samples have reached the lab, and been checked, you are also going to do different things to the samples in order to prepare them for the different data collection platforms. You'll want to know which samples should go to what platforms and have the workflows for different processes defined so that they are easy to follow and track. You might even want to track and reuse certain custom reagents like DNA primers, probes and reagent kits. In some cases you'll want to know physical information, like DNA, RNA, or concentration, upfront. In other cases you'll determine information later.

Finally, let's say you work at an institution that focuses on a specific area of research, like cancer, or mouse genetics, or plant research. In these settings you might want to also track information about sample source. Such information could include species, strain, tissue, treatment or many other kinds of things. If you want to explore this information later you'll probably want to define a vocabulary that can be "read" by computer programs. To ensure that the vocabulary can be followed, interfaces will be needed to enter this information without typing or else you'll have a problem like pseudomonas, psuedomonas, or psudomonas.

Information systems that support the above scenarios have to deal with a lot of "sometimes this" and "sometimes that" kinds of information. If one path is taken, Sanger sequencing on a 3730, different sample information and physical configurations are needed than we need with Next Gen sequencing. Next Gen platforms have different sample requirements too. SOLiD and 454 require emulsion PCR to prepare sequencing samples, whereas Solexa, amplifies DNA molecules on slides in clusters. Additionally, the information entry system also has deal with "I care" and "I don't care" kinds of data like information about sample sources, or experimental conditions. These kinds of information are needed later to understand the data in the context of the experiment, but do not have much impact on the data collection processes.

How would you create a system to support these diverse and changing requirements?

One way to do this would be to build a form with many fields and rules for filling it out. You know those kinds of forms. They say things like "ignore this section if you've filled out this other section." That would be a bad way to do this, because no one would really get things right, and the people tasked with doing the work would spend a lot of time either asking questions about what they are supposed to be doing with the samples or answering questions about how to fill out the form.

Another way would be to tell people that their work is too complex and they need custom solutions for everything they do. That's expensive.

A better way to do this would be to build a system for creating forms. In this system, different forms are created by the people who develop the different services. The forms are linked to workflows (lab procedures) that can understand sample configurations (plates, tubes, premixed ingredients, and required information). If the systems is really good, you can easily create new forms and add fields to them to collect physical information (sample type, concentration) or experimental information (tissue, species, strain, treatment, your mothers maiden name, favorite vacation spot, ...) without having to develop requirements with programmers and have them build forms. If your system is exceptionally good, smart, and clever it will let you create different kinds of forms and fields and prevent you from doing things that are in direct conflict with one another. If your system is modern, it will be 100% web-based and have cool web 2.0 features like automated fill downs, column highlighting, and multi-selection devices so that entering data is easy, intuitive, and even a bit fun.

FinchLab, built on the Finch 3 platform, is such a system.

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