Tag Archives: Vibrio vulnificus

qPCR – C.gigas V.vulnificus Exposure cDNA (from 20110311)

Ran a qPCR using 3hr Vibrio vulnificus exposure cDNA from 20110311. Original experiment conducted on 20110111 with defensin primers (SR IDs: 1109 & 1070) and GAPDH (SR IDs: 1172 & 1173). Master mix calcs are here. Cycling params, plate layout, etc can be seen in the qPCR Report (see Results). This was performed to help Herschel.

Results:

qPCR Report (PDF)

qPCR Data File (CFX96)

Initial glance at data looks good. GAPDH exhibits highly consistent Cq values across all samples, controls and exposed. Although, there is slight amplification of something in the two water samples for GAPDH, the melt curve shows that this product has a different melting temperature than our intended target. As such, I believe the GAPDH data to be useable, since no other samples exhibit this smaller product. Defensin shows clean water sample and clean melt curves with a single peak. However, it seems like we may not see an effect on defensin expression in response to the Vibrio vulnificus exposure…

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qPCR – C.gigas GAPDH second rep on V.vulnificus exposure cDNA (from 20110311) and standard curves for COX1, COX2, GAPDH

Ran a qPCR on all cDNA samples. Created a standard curve to possibly allow for use of the BioRad software for gene expression analysis. Standard curve was created from pooled cDNA (1uL from each individual sample). Master mix calcs are here.

Results:

qPCR Data File (BioRad CFX96)

qPCR Report (PDF)

Standard curves aren’t that good. Will not use them. Will analyze data using PCR Miner.

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qPCR – C.gigas actin and GAPDH on V.vulnificus exposure cDNA (from 20110311)

Ran a qPCR on all cDNA samples from the V.vulnificus exposure experiment from 20110111. This qPCR was to test 2 of 4 potential normalizing genes to evaluate which genes show the least amount of effect from the treatments in this experiment. Primers for actin used were Cg_Actin_306_F (SR ID: 1170), Cg_Actin_408_R (SR ID: 1171). Samples were run in duplicate. Master mix calcs are here. The master mix info is the same that was used earlier today, but with the primers noted above, not those listed on the calcs page. Plate layout, cycling params, etc., can be seen in the qPCR Report (see Results).

Results:

qPCR Data File (BioRad CFX96)

qPCR Report (PDF)

Actin: Average Cq = 20.21, Standard Deviation = 1.22

GAPDH: Average Cq = 24.42, Standard Deviation = 0.519

Based on the results from the 4 normalizing genes examined, I will use GAPDH as the normalizing gene due to it having the lowest standard deviation of the 4 normalizing genes. Will perform another qPCR to run a duplicate of GAPDH so that we have a second rep.

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qPCR – C.gigas 18s and EF1a on V.vulnificus exposure cDNA (from 20110311)

Ran a qPCR on all cDNA samples from the V.vulnificus exposure experiment from 20110111. This qPCR was to test 2 of 4 potential normalizing genes to evaluate which genes show the least amount of effect from the treatments in this experiment. Primers for 18s used were Cg_18s_1644_F (SR ID: 1168), Cg_18s_1750_R (SR ID: 1169). Primers for EF1a used were EF1_qPCR_5′ (SR ID: 309), EF1_qPCR_3′ (SR ID: 310)Samples were run in duplicate. Master mix calcs are here. The master mix info is the same that was used earlier today, but with the primers noted above, not those listed on the calcs page. Plate layout, cycling params, etc., can be seen in the qPCR Report (see Results).

Results:

qPCR Data File (BioRad CFX96)

qPCR Report (PDF)

18s: Average Cq = 22.39, Standard Deviation = 0.905

EF1a: Average Cq = 20.59, Standard Deviation = 0.658

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qPCR – C.gigas COX2 on V.vulnificus exposure cDNA (from 20110311)

Ran a qPCR on all cDNA samples from the V.vulnificus exposure experiment from 20110111. Primers used were Cg_COX1/2_qPCR_F (SR ID: 1192) & Cg_COX2_454align1_R (SR ID: 1190). Samples were run in duplicate. Master mix calcs are here. The master mix info is the same that was used earlier today, but with the primers noted above, not those listed on the calcs page. Plate layout, cycling params, etc., can be seen in the qPCR Report (see Results).

Results:

qPCR Data File (BioRad CFX96)

qPCR Report (PDF)

Data looks good (e.g. the replicates are all very close, with the largest Cq Std. Deviation = 1.227, although this does appear to be an anomaly as the next highest Cq Std. Deviation in any of the reps is 0.633), nothing in the NTCs, & the melt curves look good. Will eventually normalize the data and then perform a complete analysis.

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qPCR – C.gigas COX1 on V.vulnificus exposure cDNA (from 20110311)

Ran a qPCR on all cDNA samples from the V.vulnificus exposure experiment from 20110111. Primers used were Cg_COX1/2_qPCR_F (SR ID: 1192) & Cg_COX1_qPCR_R (SR ID: 1191). Samples were run in duplicate. Master mix calcs are here. Plate layout, cycling params, etc., can be seen in the qPCR Report (see Results).

Results:

qPCR Data File (BioRad CFX96)

qPCR Report (PDF)

Data looks good (e.g. the replicates are all very close, with the largest Cq Std. Deviation = 0.534), nothing in the NTCs, & the melt curves look good. Will eventually normalize the data and then perform a complete analysis.

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qPCR – Emma’s New 3KDSqPCR Primers

Due to previous contamination issues with Emma’s primers, Emma asked me to order new primers, reconstitute them and run a qPCR for her to see if we could eliminate her contamination issues with this primer set. cDNA template was supplied by Emma (from 2/2/11) and was from a C.gigas 3hr Vibrio vulnificus challenge. Samples were run in duplicate, as requested. Master mix calcs are here. Plate layout, cycling params, etc. can be found in the qPCR Report (see Results). Primer set used was:

Cg_3KDSqPCR_F/R (SR IDs: 1186, 1187)

Results:

qPCR Data File (BioRad CFX96)

qPCR Report (PDF)

The negative controls (NTC) are negative, meaning they do not cross the threshold set by the BioRad software. However, there is clearly amplification in the NTCs, but they come up late enough that they do not cross the threshold and, thus, generate a Cq value. Additionally, the melt curve reveals peaks in the NTCs that are at the same melting temperature as the product produced in the cDNA qPCR reactions. This would potentially imply some sort of contamination, as Emma has experienced.

Honestly, I do no think contamination is the problem. I believe that the “contamination” being seen in the NTCs is actually primer dimer. Increasing the annealing temperature (I’m not sure if Emma tried this during her troubleshooting) could potentially alleviate this issue. However, I’m not sure she’s amplifying the target that she wants to. Based on my analysis, I think she needs to re-design primers for her 3KDS target. Read my analysis and why I came to this conclusion below.

It seems unlikely that two independent people (and multiple primer stock replacements!) would have contamination, so I looked in to things a bit further.

I BLASTed the primer sets (NCBI, blastn, est_others db, C.gigas only) and the BLAST results reveal the primers matching with a C.gigas EST sequence that would produce a band of only 63bp. Here’s a screen capture of the BLAST results:

This result does NOT agree with what is entered in our Primer Database. As entered in our sheet, the expected PCR product would be ~102bp. However, taking in to account the BLAST results, it would be difficult to distinguish the difference between primer dimers and PCR product in a melt curve analysis.

Emma has previously run a conventional PCR with these primers and ran a gel (see below). At the time, it was thought to be contamination, but in retrospect (knowing the results of the qPCRs and the BLAST results) it seems likely that what she’s seeing in the negative controls was actually primer dimer, which was the same size of her PCR product (which she thought should be larger). Additionally, the gel was difficult to interpret because no ladder was run. A ladder might have revealed that her PCR product was half the size that she was expecting:

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qPCR – C.gigas COX1/COX2 Tissue Distribution

Performed qPCR using pooled cDNA from 20110311. Pooled 2uL from each of the following samples groups: Dg 3hr C, Gill 1hr C, Gill 1hr E, Mantle 3hr C, and Muscle 3hr C. Master mix calcs are here. Plate layout, cycling params, etc can be found in the qPCR Report (see Results). Primers sets run were:

EF1_qPCR_5′,3′ (SR IDs: 309, 310)

Cg_COX1/2_qPCR_F (SR ID: 1192) + Cg_COX1_qPCR_R (SR ID: 1191)- Target = COX1

Cg_COX1/2_qPCR_F (SR ID: 1192) + Cg_COX2_454align1_R (SR ID: 1190) – Target = COX2

Results:

qPCR Report (PDF)

qPCR Data File (CFX96)

Graphs were generated using the BioRad CFX Manager v2.0 software. Expression was normalized to EF1. Also to note, gene efficiency was assumed as 100% by the software since no standard curve was run on the plate. As such, analysis of this data may not be exact.

It’s clear by examining the graphs that the primers being used to differentiate COX1 and COX2 (since they share a common primer: SRID 1192) are differentially expressed. This indicates that the primer sets are indeed amplifying different targets as hoped. This was the primary intention of this qPCR. However, we also now have an idea of tissue distribution of the two genes, as well as their response to V. vulnificus exposre after 1hr. Next step is to perform this qPCR on all the individuals from this experiment as well as the different tissues.

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Bacterial Dilutions – Determination of Colony Forming Units from Gigas Bacterial challenge (from earlier today)

All dilutions were performed with 1x LB+ 1%NaCl. 100uL were plated of all dilutions (see below) on 1xLB+1%NaCL plates. Plates were incubated O/N @ 37C. Colonies will be counted tomorrow to determine CFU for each sample.

Plated 100uL of:

V.vulnificus, t=0, 1:1,000,000 and 1:10,000,000

V.vulnificus H2O sample, t=1 & 3, 1:10,000 and 1:1,000,000

V.tubiashii, t=0, 1:1,000,000

Control H2O sample, t=1 & 3, Undiluted

Samples tubes containing bacteria and dilutions were stored @ 4C.

UPDATE 20110112:

Colony counts and calculations

V.vulnificus 0hr = Both dilutions produced a total lawn of bacteria. Uncountable. Will plate higher dilutions, but this will now only be a rough estimate due to the time that has passed.

—UPDATE—

New serial dilutions (90uL plated) of V.vulnificus 0hr were performed, down to 10^12. The only countable plate was the 10^12 dilution.

V.vulnificus 0hr = 10^12 dilution x 410 CFU = 4.1×10^14 CFU/90uL = 4.56×10^12 CFU/uL x 8×10^6uL (8L H2O in oyster tank) = 3.64×10^19 CFU total in oyster tank/8L = 4.56×10^18 CFU/L

V.vulnificus 1hr = 1:1,000,000 dilution x 48 CFU = 4.8×10^7 CFU/100uL = 4.8×10^5 CFU/uL x 8×10^6uL (8L H2O in oyster tank) = 3.84×10^12 CFU total in oyster tank/8L = 4.8×10^11 CFU/L

V.vulnificus 3hr = 1:1,000,000 dilution x 23 CFU = 2.3×10^7 CFU/100uL = 2.3×10^5 CFU/uL x 8×10^6uL (8L H2O in oyster tank) = 1.84×10^12 CFU total in oyster tank/8L = 2.3×10^11 CFU/L

Control H2O (no significant growth occurred O/N, just tiny colonies; continued incubation to allow colonies to increase in size for easier counting)

Control H2O 1hr = Undiluted 146 CFU/100uL = 1.46 CFU/uL x 8×10^6uL (8L H2O in oyster tank) = 1.168×10^7 CFU total in oyster tank/8L = 1.46×10^6 CFU/L

Control H2O 3hr = Undiluted 106 CFU/100uL = 1.06 CFU/uL x 8×10^6uL (8L H2O in oyster tank) = 8.48×10^6 CFU total in oyster tank/8L = 1.06×10^5 CFU/L

V.tubiashii 0hr = 1:1,000,000 dilution x 31 CFU = 3.1×10^7 CFU/100uL = 3.1×10^5 CFU/uL x 5×10^4 (50mL total volume of bacteria) = 1.55×10^10 CFU total V.tubiashii

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Gigas Bacterial Challenge – 1hr & 3hr Challenges with Vibrio vulnificus

400mL O/N culture (1x LB+1% NaCl, 37C, 150RPM, 1L flask) of V.vulnificus (STRAIN??) and V.tubiashii (Strain: RE22) were pelleted (4300RPM, 25C, Sorvall ST-H750 rotor). Supe was removed and pellets were each resuspended in 50mL sea water. 1mL was taken from each to use for dilutions to determine colony forming units (CFU).

Two containers were set up with each containing 16 C.gigas, and air stone and 8L of sea water. The entire 50mL of V.vulnificus was added to one of the containers. 8 oysters were sampled (gill and mantle tissue) from each container at 1hr and 3hrs after the addition of V.vulnificus culture and immediately frozen on dry ice. Samples were stored @ -80C in the “Gigas Vibrio Exposure 1,3hrs 1/11/11″ box. Additionally, 1mL samples of the water were taken at each time to determine CFU in the water.

In addition to the samples taken above, the following tissues were taken from 5 control oysters at the 3hr time point and treated/stored in the same fashion as the others, specifically for assessment of cyclooxygenase tissue distribution analysis: muscle, digestive gland/gonad (difficult to differentiate)

All oysters were measured. Morphometric data is here.

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