The denaturation of double-stranded DNA occurs over a range of temperatures. Beginning from a helical state, DNA will transition to a random-coil state as temperature is increased. MeltDNA predicts the positional helicity, melt curve, or its negative derivate at different temperatures.
Usage
MeltDNA(myDNAStringSet,
type = "derivative",
temps = 50:100,
ions = 0.2)
Arguments
myDNAStringSet
A DNAStringSet object or character vector with one or more sequences in 5' to 3' orientation.
type
Character string indicating the type of results desired. This should be (an abbreviation of) one of "derivative curves", "melt curves", or "positional probabilities".
temps
Numeric vector of temperatures (in degrees Celsius).
ions
Numeric giving the molar sodium equivalent ionic concentration. Values must be at least 0.01M.
Details
When designing a high resolution melt (HRM) assay, it is useful to be able to predict the results before performing the experiment. Multi-state models of DNA melting can provide near-qualitative agreement with experimental DNA melt curves obtained with quantitative PCR (qPCR). MeltDNA employs the algorithm of Tostesen et al. (2003) with an approximation for loop entropy that runs in nearly linear time and memory, which allows very long DNA sequences (up to 100,000 base pairs) to be analyzed.
Denaturation is a highly cooperative process whereby regions of double-stranded DNA tend to melt together. For short sequences (< 100 base pairs) there is typically a single transition from a helical to random-coil state. Longer sequences may exhibit more complex melting behavior with multiple peaks, as domains of the DNA melt at different temperatures. The melting curve represents the average fractional helicity (Theta) at each temperature, and can be used for genotyping with high resolution melt analysis.
Value
MeltDNA can return three types of results: positional helicity, melting curves, or the negative derivative of the melting curves. If type is "position", then a list is returned with one component for each sequence in myDNAStringSet. Each list component contains a matrix with the probability of helicity (Theta) at each temperature (rows) and every position in the sequence (columns).
If type is "melt", then a matrix with the average Theta across the entire sequence is returned. This matrix has a row for each input temperature (temps), and a column for each sequence in myDNAStringSet. For example, the value in element [3, 4] is the average helicity of the fourth input sequence at the third input temperature. If type is "derivative" then the values in the matrix are the derivative of the melt curve at each temperature.
Note
MeltDNA uses nearest neighbor parameters from SantaLucia (1998).
SantaLucia, J. (1998). A unified view of polymer, dumbbell, and oligonucleotide DNA nearest-neighbor thermodynamics. Proceedings of the National Academy of Sciences, 95(4), 1460-1465.
Tostesen, E., et al. (2003). Speed-up of DNA melting algorithm with complete nearest neighbor properties. Biopolymers, 70(3), 364-376. doi:10.1002/bip.10495.
fas <- system.file("extdata", "IDH2.fas", package="DECIPHER")
dna <- readDNAStringSet(fas)
# plot the melt curve for the two alleles
temps <- seq(85, 100, 0.2)
m <- MeltDNA(dna,
type="melt", temps=temps, ions=0.1)
matplot(temps, m,
type="l", xlab="Temperature (u00B0C)", ylab="Average Theta")
legend("topright", names(dna), lty=seq_along(dna), col=seq_along(dna))
# plot the negative derivative curve for a subsequence of the two alleles
temps <- seq(80, 95, 0.25)
m <- MeltDNA(subseq(dna, 492, 542),
type="derivative", temps=temps)
matplot(temps, m,
type="l", xlab="Temperature (u00B0C)", ylab="-d(Theta)/dTemp")
legend("topright", names(dna), lty=seq_along(dna), col=seq_along(dna))
# plot the positional helicity profile for the IDH2 allele
temps <- seq(90.1, 90.5, 0.1)
m <- MeltDNA(dna[1],
type="position", temps=temps, ions=0.1)
matplot(seq_len(dim(m[[1]])[2]), t(m[[1]]),
type="l", xlab="Nucleotide Position", ylab="Theta")
temps <- formatC(temps, digits=1, format="f")
legend("topright", legend=paste(temps, "u00B0C", sep=""),
col=seq_along(temps), lty=seq_along(temps), bg="white")
Results
R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.
R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.
Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.
> library(DECIPHER)
Loading required package: Biostrings
Loading required package: BiocGenerics
Loading required package: parallel
Attaching package: 'BiocGenerics'
The following objects are masked from 'package:parallel':
clusterApply, clusterApplyLB, clusterCall, clusterEvalQ,
clusterExport, clusterMap, parApply, parCapply, parLapply,
parLapplyLB, parRapply, parSapply, parSapplyLB
The following objects are masked from 'package:stats':
IQR, mad, xtabs
The following objects are masked from 'package:base':
Filter, Find, Map, Position, Reduce, anyDuplicated, append,
as.data.frame, cbind, colnames, do.call, duplicated, eval, evalq,
get, grep, grepl, intersect, is.unsorted, lapply, lengths, mapply,
match, mget, order, paste, pmax, pmax.int, pmin, pmin.int, rank,
rbind, rownames, sapply, setdiff, sort, table, tapply, union,
unique, unsplit
Loading required package: S4Vectors
Loading required package: stats4
Attaching package: 'S4Vectors'
The following objects are masked from 'package:base':
colMeans, colSums, expand.grid, rowMeans, rowSums
Loading required package: IRanges
Loading required package: XVector
Loading required package: RSQLite
Loading required package: DBI
> png(filename="/home/ddbj/snapshot/RGM3/R_BC/result/DECIPHER/MeltDNA.Rd_%03d_medium.png", width=480, height=480)
> ### Name: MeltDNA
> ### Title: Simulate Melting of DNA
> ### Aliases: MeltDNA
>
> ### ** Examples
>
> fas <- system.file("extdata", "IDH2.fas", package="DECIPHER")
> dna <- readDNAStringSet(fas)
>
> # plot the melt curve for the two alleles
> temps <- seq(85, 100, 0.2)
> m <- MeltDNA(dna,
+ type="melt", temps=temps, ions=0.1)
> matplot(temps, m,
+ type="l", xlab="Temperature (u00B0C)", ylab="Average Theta")
> legend("topright", names(dna), lty=seq_along(dna), col=seq_along(dna))
>
> # plot the negative derivative curve for a subsequence of the two alleles
> temps <- seq(80, 95, 0.25)
> m <- MeltDNA(subseq(dna, 492, 542),
+ type="derivative", temps=temps)
> matplot(temps, m,
+ type="l", xlab="Temperature (u00B0C)", ylab="-d(Theta)/dTemp")
> legend("topright", names(dna), lty=seq_along(dna), col=seq_along(dna))
>
> # plot the positional helicity profile for the IDH2 allele
> temps <- seq(90.1, 90.5, 0.1)
> m <- MeltDNA(dna[1],
+ type="position", temps=temps, ions=0.1)
> matplot(seq_len(dim(m[[1]])[2]), t(m[[1]]),
+ type="l", xlab="Nucleotide Position", ylab="Theta")
> temps <- formatC(temps, digits=1, format="f")
> legend("topright", legend=paste(temps, "u00B0C", sep=""),
+ col=seq_along(temps), lty=seq_along(temps), bg="white")
>
>
>
>
>
> dev.off()
null device
1
>