Regulatory

All but one of the regulatory elements we isolated are promoters, and are described in brief detail below, with more elaborate information on their parts registry pages. The remaining BioBrick is the 3' UTR from unc-54, which is roughly equivalent to a bacterial terminator and performs a number of important regulatory functions in complement to the promoter. All complete C. elegans constructs must include some form of functional 3' UTR. Promoters were selected based on their utility, strength of expression, and ease of avoiding potentially harmful cutsites.

Constitutive

• pGpd-2: gpd-2 is part of the glycolysis pathway. The gpd-2 promoter thus expresses at a very high level—AceView says 43.5 times the average for a C. elegans constitutive gene.
• pSip-1: sip-1 encodes a member of the heat shock family of proteins. Accoring to AceView, sip-1 is expressed at a level 17.6 times the average, at all levels of development.
• pRab-7: rab-7 expresses a GTPase involved in endosome trafficking, and expresses at 4.3 times the average.

Inducible

• pHsp-3: HSP-3 is a protein involved in the heat shock response pathway, and is expressed constitutively. AceView says this is 22.9 times the average. However, WormBase asserts that transcriptional levels can be enhanced by the presence of diothiothreitol or tunicamycin.

Tissue-Specific

These all target different sensory neurons. For more information on what most of these neurons do, see our section on the amphid.

• pMec-7: This targets the mechanoreceptor neurons. We were able to use it in a construct successfully with eCFP and our 3' UTR brick: see its page on the parts registry.
• pOdr-1: This targets the AWC sensory neuron.
• pStr-1: This targets the AWB sensory neuron.
• pOsm-10: This targets the ASH and ASI sensory neurons, as well as the PHA and PHB phasmid neurons.
• pFlp-1: This targets the AVA sensory neuron.
• pSra-10: This targets the AVB sensory neuron.
• pStr-220: This targets the AWC sensory neuron.

Reporters

• eGFP: excitation: 395 nm; emission: 509 nm.
• eCFP: excitation: 433 nm; emission: 475 nm.
• eYFP: excitation: ~485 nm; emission: ~700 nm.
• mCherry: excition: ~580 nm; emission: ~620 nm.

Optogenetics Proteins

• ChR2 (channelrhodopsin-2): A surface protein. Excitation by light at 460 nm causes the admission of cations into the cell. These cations are nonspecific (H⁺, K⁺, Na⁺, Ca²⁺), but can directly trigger the depolarization of a neuron, forcing it into a firing state where it will remain until the light source is removed.
• NpHR (halorhodopsin): A surface protein. Excitation by light at 580 nm causes the admission of chloride anions into the cell. If used in a neuron, this can prevent it from firing as long as the light source is present.
• Fusions: ChR2::eYFP and NpHR::eCFP are both also provided. These are useful for ensuring that the channels localized successfully to their target.

The excitation wavelengths of these two proteins are different enough that they can actually be implemented in the same organism and triggered separately, with very little cross-talk. This means that it is possible to control two different neural inputs in the same worm at the same time. Such an arrangement opens up many possibilities, such as using one protein to convince the worm that it needs to go forward, and another that that it needs to go backwards. Similarly, one protein could be used to trigger the worm to turn, and another to keep it going straight.

Constructs

Unlike the fusions listed under Optogenetics Proteins, these were assembled through BioBrick digestion/ligation.

• pStr-220::eCFP::unc-54 3' UTR
• pOdr-10::eCFP::unc-54 3' UTR
• pGpd-2::eCFP::unc-54 3' UTR
• pSip1::eCFP::unc-54 3' UTR
• pFlp1::eCFP:unc-54 3' UTR
• ChR2::eYFP::unc-54 3' UTR
• pHsp3::eCFP::unc-54 3' UTR
• pOsm-10::eCFP::unc-54 3' UTR
• mCherry::unc-54 3' UTR
• eYFP::unc-54 3' UTR
• pOdr-1::eCFP::unc-54 3' UTR
• pMec-7::eCFP::unc-54 3' UTR

Getting the Parts

You can get our special worm parts through the standard iGEM distribution channel: the Parts Registry. Click on a part number below to be taken to the relevant description page.