Team:Yale/Our Project/Notebook/Week 2

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lab notebook: week 2 (6/14-6/20)

• Monday 6/14--Redo of 6/11 assay of bacterial growth within a narrow copper(II) concentrations after analysis of data showed uniformly poor growth.
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Copper Growth Assay Work Continues

• As the growth assay of 6/11 showed uniformly poor growth even at the lowest copper concentrations (see Dh5alpha growth above), redid it with care not to let the liquid cultures overgrow, a possible source of the cultures' previous poor performance. (add plot)
• In redoing plate assay, changed copper concentration line-up slightly, eliminating 1.25 mM and 2.5 mM trials to allow room for the control concentrations, 0 and 1 M, and only worked with high because there was no real distinction in the three different OD trials done on 6/10. For simplicity, future assays will only use one starting OD (0.075) per strain.
• During the repeat, noticed that DH5alpha liquid culture grown up for plate reader assay grew at a rate much slower than that of LE392, creating a need to keep diluting the LE392 solution with more LB so it would not overgrow before the DH5alpha was ready. In the end, the culture of LE392 used in the assay was diluted from an OD of 0.761 and the DH5alpha culture from an OD of 0.841.

This day's work is also recorded on pages 8-10 of the lab notebook hard copy.
• Tuesday 6/15--Results and analysis of the 6/14 narrow concentration range growth assay as well as planning for the creation of a standard iGEM plasmid bearing the thiosulfate reductase operon (phsABC).
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Results and Conclusions of Narrow Concentration Range Growth Assay of 6/14

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• Negative readings for the 4 mM samples suggest that there was some sort of irregularity with the blank solution, so will disregard those results.
• Can see growth really starts to slow down at 3 mM concentrations of Cu²⁺
• It’s unclear whether the cells at the higher copper concentrations die or simply stop growing. Spot a drop from each well of the plate onto a LB agar plate and incubate overnight at 37˚C. Will check for growth to determine survival of different strains at different copper concentrations.

Plasmid Ligation Strategy & Primer Design

The Plan for phs plasmid creation
The phs operon has three genes of interest to us, A, B, and C, that code for different protein products and together are responsible for hydrogen sulfide production. We will use these genes to create a number of different plasmids described below. Plasmids to be made:
Plasmid 1 gives our basic thiosulfate reductase pathway under IPTG control. Plasmid 5 is a light-controlled analog that we will make if we can find a suitable light-inducible promoter. Plasmid 2 is a promoter-less “generator” to be archived so other teams can use it. Plasmids 3 & 4 are a set and together give the entire pathway. The idea is that since protein production takes a while we will make only part of the pathway inducible. The cell will constitutively produce the A & B products, so after the light hits only the small C protein remains to be made.


Product	Promoter	Gene	Terminator	Plasmid Vector
1	IPTG-inducible pSB1A2 (well 6G plate 1)	phsABC	BBa_B0015	pSB1C3 (chloramphenicol resistance)

• Wednesday 6/16--checked on spotted cell survival assay, collected MOPS minimal media materials, started making component solutions
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• Thursday 6/17--more minimal media work and meeting, started BL21 culture
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• Friday 6/18--plasmid pSB74 arrived (!), already in some unspecified E coli, so plated them out. Transformed promoters (constitutive & IPTG inducible), terminator, and repressor (for inducible promoter) into BL21. Also ran BL21 copper growth assays for wide and narrow concentrations ranges. June the 19th--in which it is revealed that there was a transformation-fail Redid transformation, this time into LE392, set aside pSB74 containing cells in fridge
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• Sunday 6/20--in evening inoculate 5 mL liquid cultures
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