Last updated: 2020-11-30

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Knit directory: bios_2020_single-cell-workshop-svi/

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Rmd eab0b17 rlyu 2020-11-16 finalising analysis workflow and sctransform
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sctransform

Different from the size_factor-based normalisation method that we used before, sctransform is based on probabilistic models for normalisation and variance stablisation of UMI-count data from scRNAseq. Instead of using a constant factor for normalising all genes for one cell, sctransform (Hafemeister and Satija 2019) models and scales each gene individually.

sctransform fits a generalised linear model with a negative binomial error model for each gene with the sequencing depth (library size) as a covariate followed by a regularisation procedure to control overfitting. The residuals from the regularised regression model is then treated as normalised expression levels with variation caused by sequencing depth removed.

suppressPackageStartupMessages({
    library(sctransform)
    library(ggplot2)
    library(scater)
    library(scran)
  }
)
sce.pbmc <- readRDS(file = "raw_data/sce_pbmc.rds")

We use the log10_umi as the latent variable that will be regressed out in the normalised gene expression values.

set.seed(10000)

colData(sce.pbmc)$log10_umi <- log(colData(sce.pbmc)$total,base=10)
pbmc.sctrans <- suppressWarnings(sctransform::vst(assay(sce.pbmc,"counts"), 
                                 cell_attr = colData(sce.pbmc),
                                 latent_var = "log10_umi", verbosity = FALSE))

## Warning related issue: https://github.com/ChristophH/sctransform/issues/25
#str(pbmc.sctrans)

Add to assay field

pbmc.sctrans stores returned value from running variance stablisation using sctransform. The normalised values are stored in the matrix y. We now add y to the sce object in the assay field with asaay name “SCT”. This is equivalant to the logcounts assay.

## Less genes will be returned by sctransform which filtered out genes that are
## only detected in 5 or less cells.
sce.pbmc <- sce.pbmc[rownames(pbmc.sctrans$y),]
assay(sce.pbmc,"SCT") <- pbmc.sctrans$y

Select highly variable genes

Feature selection after sctransform normalisation is straightforward. We can just select the top genes that have a high residual variance which contribute the most biological sources of variation.

head(round(pbmc.sctrans$gene_attr[order(-pbmc.sctrans$gene_attr$residual_variance), ], 2), 
    22)
          detection_rate gmean variance residual_mean residual_variance
IGKC                0.27  0.60   184.08          2.89            135.91
S100A8              0.62  2.15   633.20          3.75            125.33
S100A9              0.70  2.70   921.73          3.68            113.23
GNLY                0.24  0.45    74.24          2.05             96.29
LYZ                 0.65  2.82  1042.16          3.70             82.80
IGLC3               0.10  0.16   590.98          1.11             71.41
IGLC2               0.19  0.26 16209.67          1.16             69.35
NKG7                0.38  0.84    45.18          1.76             41.94
PPBP                0.03  0.05    10.27          0.55             41.88
PF4                 0.03  0.04     3.27          0.55             41.33
CCL5                0.35  0.85    38.41          1.70             32.14
SDPR                0.02  0.03     1.20          0.44             31.22
GNG11               0.04  0.04     1.01          0.43             30.53
HIST1H2AC           0.06  0.06     2.78          0.42             27.31
GZMB                0.10  0.14     9.18          0.62             27.26
TUBB1               0.02  0.03     1.27          0.39             27.14
CD74                0.92  6.11  1597.07          1.75             26.45
FTL                 0.99 12.79  1475.18          1.45             22.33
JCHAIN              0.07  0.09    12.44          0.40             21.84
S100A12             0.26  0.49    16.41          0.95             21.73
KLRB1               0.24  0.46    15.92          0.99             21.64
CST3                0.56  1.77   306.70          1.51             21.15

select 3,000 highly variable genes for downstream analysis

hvgs_3k <- rownames(round(pbmc.sctrans$gene_attr[order(-pbmc.sctrans$gene_attr$residual_variance), ], 2), 
    3000)

runPCA with HVGs

Next, we runPCA with the selected number of highly variable genes.

set.seed(10000)
sce.pbmc <- runPCA(sce.pbmc,exprs_values="SCT",ncomponents=10,
                   subset_row=hvgs_3k)

Generate TSNE plot using PCs

set.seed(10000)
sce.pbmc <- runTSNE(sce.pbmc, dimred="PCA")
sce.pbmc <- runUMAP(sce.pbmc, dimred="PCA")

Clustering

The remaining steps are similar to those presented in the main workflow.

g <- buildSNNGraph(sce.pbmc, k=35, use.dimred = 'PCA')
clust <- igraph::cluster_walktrap(g)$membership
colLabels(sce.pbmc) <- factor(clust)

Plot Clusters

plotTSNE(sce.pbmc, colour_by="label")

Version Author Date
eab0b17 rlyu 2020-11-16
plotUMAP(sce.pbmc, colour_by="label")

Version Author Date
eab0b17 rlyu 2020-11-16
plotExpression(sce.pbmc, features=c("CD14", "CD68",
    "MNDA", "FCGR3A"), x="label", colour_by="label",exprs_values = "SCT")

Version Author Date
eab0b17 rlyu 2020-11-16

More info

sctransform is also integrated and interfaced with Seurat package which you can find more information here: https://satijalab.org/seurat/v3.2/sctransform_vignette.html

References

SessionInfo

sessionInfo()
R version 4.0.3 (2020-10-10)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Red Hat Enterprise Linux

Matrix products: default
BLAS/LAPACK: /usr/lib64/libopenblasp-r0.3.3.so

locale:
 [1] LC_CTYPE=en_AU.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_AU.UTF-8        LC_COLLATE=en_AU.UTF-8    
 [5] LC_MONETARY=en_AU.UTF-8    LC_MESSAGES=en_AU.UTF-8   
 [7] LC_PAPER=en_AU.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] parallel  stats4    stats     graphics  grDevices utils     datasets 
[8] methods   base     

other attached packages:
 [1] scran_1.18.0                scater_1.18.0              
 [3] SingleCellExperiment_1.12.0 SummarizedExperiment_1.20.0
 [5] Biobase_2.50.0              GenomicRanges_1.42.0       
 [7] GenomeInfoDb_1.26.0         IRanges_2.24.0             
 [9] S4Vectors_0.28.0            BiocGenerics_0.36.0        
[11] MatrixGenerics_1.2.0        matrixStats_0.57.0         
[13] ggplot2_3.3.2               sctransform_0.3.1          

loaded via a namespace (and not attached):
 [1] bitops_1.0-6              fs_1.5.0                 
 [3] rprojroot_1.3-2           tools_4.0.3              
 [5] backports_1.2.0           R6_2.5.0                 
 [7] irlba_2.3.3               vipor_0.4.5              
 [9] uwot_0.1.8                colorspace_1.4-1         
[11] withr_2.3.0               tidyselect_1.1.0         
[13] gridExtra_2.3             compiler_4.0.3           
[15] git2r_0.27.1              BiocNeighbors_1.8.0      
[17] DelayedArray_0.16.0       labeling_0.4.2           
[19] scales_1.1.1              stringr_1.4.0            
[21] digest_0.6.27             rmarkdown_2.5            
[23] XVector_0.30.0            pkgconfig_2.0.3          
[25] htmltools_0.5.0           parallelly_1.21.0        
[27] sparseMatrixStats_1.2.0   limma_3.46.0             
[29] rlang_0.4.8               rstudioapi_0.11          
[31] FNN_1.1.3                 DelayedMatrixStats_1.12.0
[33] farver_2.0.3              generics_0.1.0           
[35] BiocParallel_1.24.0       dplyr_1.0.2              
[37] RCurl_1.98-1.2            magrittr_1.5             
[39] BiocSingular_1.6.0        GenomeInfoDbData_1.2.4   
[41] scuttle_1.0.0             Matrix_1.2-18            
[43] Rcpp_1.0.5                ggbeeswarm_0.6.0         
[45] munsell_0.5.0             viridis_0.5.1            
[47] lifecycle_0.2.0           stringi_1.5.3            
[49] whisker_0.4               yaml_2.2.1               
[51] edgeR_3.32.0              MASS_7.3-53              
[53] zlibbioc_1.36.0           Rtsne_0.15               
[55] plyr_1.8.6                grid_4.0.3               
[57] listenv_0.8.0             promises_1.1.1           
[59] dqrng_0.2.1               crayon_1.3.4             
[61] lattice_0.20-41           cowplot_1.1.0            
[63] beachmat_2.6.0            locfit_1.5-9.4           
[65] knitr_1.30                pillar_1.4.6             
[67] igraph_1.2.6              future.apply_1.6.0       
[69] reshape2_1.4.4            codetools_0.2-16         
[71] glue_1.4.2                evaluate_0.14            
[73] vctrs_0.3.4               httpuv_1.5.4             
[75] gtable_0.3.0              purrr_0.3.4              
[77] future_1.20.1             xfun_0.19                
[79] rsvd_1.0.3                RSpectra_0.16-0          
[81] later_1.1.0.1             viridisLite_0.3.0        
[83] tibble_3.0.4              beeswarm_0.2.3           
[85] workflowr_1.6.2           statmod_1.4.35           
[87] bluster_1.0.0             globals_0.13.1           
[89] ellipsis_0.3.1           

Hafemeister, Christoph, and Rahul Satija. 2019. “Normalization and Variance Stabilization of Single-Cell RNA-seq Data Using Regularized Negative Binomial Regression.” Genome Biol. 20 (1): 296.


devtools::session_info()
─ Session info ───────────────────────────────────────────────────────────────
 setting  value                       
 version  R version 4.0.3 (2020-10-10)
 os       Red Hat Enterprise Linux    
 system   x86_64, linux-gnu           
 ui       X11                         
 language (EN)                        
 collate  en_AU.UTF-8                 
 ctype    en_AU.UTF-8                 
 tz       Australia/Melbourne         
 date     2020-11-30                  

─ Packages ───────────────────────────────────────────────────────────────────
 package              * version  date       lib source        
 assertthat             0.2.1    2019-03-21 [1] CRAN (R 4.0.2)
 backports              1.2.0    2020-11-02 [1] CRAN (R 4.0.2)
 beachmat               2.6.0    2020-10-27 [1] Bioconductor  
 beeswarm               0.2.3    2016-04-25 [1] CRAN (R 4.0.2)
 Biobase              * 2.50.0   2020-10-27 [1] Bioconductor  
 BiocGenerics         * 0.36.0   2020-10-27 [1] Bioconductor  
 BiocNeighbors          1.8.0    2020-10-27 [1] Bioconductor  
 BiocParallel           1.24.0   2020-10-27 [1] Bioconductor  
 BiocSingular           1.6.0    2020-10-27 [1] Bioconductor  
 bitops                 1.0-6    2013-08-17 [1] CRAN (R 4.0.2)
 bluster                1.0.0    2020-10-27 [1] Bioconductor  
 callr                  3.5.1    2020-10-13 [1] CRAN (R 4.0.2)
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 DelayedMatrixStats     1.12.0   2020-10-27 [1] Bioconductor  
 desc                   1.2.0    2018-05-01 [1] CRAN (R 4.0.2)
 devtools               2.3.2    2020-09-18 [1] CRAN (R 4.0.2)
 digest                 0.6.27   2020-10-24 [1] CRAN (R 4.0.2)
 dplyr                  1.0.2    2020-08-18 [1] CRAN (R 4.0.2)
 dqrng                  0.2.1    2019-05-17 [1] CRAN (R 4.0.2)
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 ellipsis               0.3.1    2020-05-15 [1] CRAN (R 4.0.2)
 evaluate               0.14     2019-05-28 [1] CRAN (R 4.0.2)
 fansi                  0.4.1    2020-01-08 [1] CRAN (R 4.0.2)
 farver                 2.0.3    2020-01-16 [1] CRAN (R 4.0.2)
 FNN                    1.1.3    2019-02-15 [1] CRAN (R 4.0.2)
 fs                     1.5.0    2020-07-31 [1] CRAN (R 4.0.2)
 future                 1.20.1   2020-11-03 [1] CRAN (R 4.0.2)
 future.apply           1.6.0    2020-07-01 [1] CRAN (R 4.0.2)
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 GenomeInfoDb         * 1.26.0   2020-10-27 [1] Bioconductor  
 GenomeInfoDbData       1.2.4    2020-11-04 [1] Bioconductor  
 GenomicRanges        * 1.42.0   2020-10-27 [1] Bioconductor  
 ggbeeswarm             0.6.0    2017-08-07 [1] CRAN (R 4.0.2)
 ggplot2              * 3.3.2    2020-06-19 [1] CRAN (R 4.0.2)
 git2r                  0.27.1   2020-05-03 [1] CRAN (R 4.0.2)
 globals                0.13.1   2020-10-11 [1] CRAN (R 4.0.2)
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 gridExtra              2.3      2017-09-09 [1] CRAN (R 4.0.2)
 gtable                 0.3.0    2019-03-25 [1] CRAN (R 4.0.2)
 htmltools              0.5.0    2020-06-16 [1] CRAN (R 4.0.2)
 httpuv                 1.5.4    2020-06-06 [1] CRAN (R 4.0.2)
 igraph                 1.2.6    2020-10-06 [1] CRAN (R 4.0.2)
 IRanges              * 2.24.0   2020-10-27 [1] Bioconductor  
 irlba                  2.3.3    2019-02-05 [1] CRAN (R 4.0.2)
 knitr                  1.30     2020-09-22 [1] CRAN (R 4.0.2)
 labeling               0.4.2    2020-10-20 [1] CRAN (R 4.0.2)
 later                  1.1.0.1  2020-06-05 [1] CRAN (R 4.0.2)
 lattice                0.20-41  2020-04-02 [2] CRAN (R 4.0.3)
 lifecycle              0.2.0    2020-03-06 [1] CRAN (R 4.0.2)
 limma                  3.46.0   2020-10-27 [1] Bioconductor  
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 locfit                 1.5-9.4  2020-03-25 [1] CRAN (R 4.0.2)
 magrittr               1.5      2014-11-22 [1] CRAN (R 4.0.2)
 MASS                   7.3-53   2020-09-09 [2] CRAN (R 4.0.3)
 Matrix                 1.2-18   2019-11-27 [2] CRAN (R 4.0.3)
 MatrixGenerics       * 1.2.0    2020-10-27 [1] Bioconductor  
 matrixStats          * 0.57.0   2020-09-25 [1] CRAN (R 4.0.2)
 memoise                1.1.0    2017-04-21 [1] CRAN (R 4.0.2)
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 parallelly             1.21.0   2020-10-27 [1] CRAN (R 4.0.2)
 pillar                 1.4.6    2020-07-10 [1] CRAN (R 4.0.2)
 pkgbuild               1.1.0    2020-07-13 [1] CRAN (R 4.0.2)
 pkgconfig              2.0.3    2019-09-22 [1] CRAN (R 4.0.2)
 pkgload                1.1.0    2020-05-29 [1] CRAN (R 4.0.2)
 plyr                   1.8.6    2020-03-03 [1] CRAN (R 4.0.2)
 prettyunits            1.1.1    2020-01-24 [1] CRAN (R 4.0.2)
 processx               3.4.4    2020-09-03 [1] CRAN (R 4.0.2)
 promises               1.1.1    2020-06-09 [1] CRAN (R 4.0.2)
 ps                     1.4.0    2020-10-07 [1] CRAN (R 4.0.2)
 purrr                  0.3.4    2020-04-17 [1] CRAN (R 4.0.2)
 R6                     2.5.0    2020-10-28 [1] CRAN (R 4.0.2)
 Rcpp                   1.0.5    2020-07-06 [1] CRAN (R 4.0.2)
 RCurl                  1.98-1.2 2020-04-18 [1] CRAN (R 4.0.2)
 remotes                2.2.0    2020-07-21 [1] CRAN (R 4.0.2)
 reshape2               1.4.4    2020-04-09 [1] CRAN (R 4.0.2)
 rlang                  0.4.8    2020-10-08 [1] CRAN (R 4.0.2)
 rmarkdown              2.5      2020-10-21 [1] CRAN (R 4.0.2)
 rprojroot              1.3-2    2018-01-03 [1] CRAN (R 4.0.2)
 RSpectra               0.16-0   2019-12-01 [1] CRAN (R 4.0.2)
 rstudioapi             0.11     2020-02-07 [1] CRAN (R 4.0.2)
 rsvd                   1.0.3    2020-02-17 [1] CRAN (R 4.0.2)
 Rtsne                  0.15     2018-11-10 [1] CRAN (R 4.0.2)
 S4Vectors            * 0.28.0   2020-10-27 [1] Bioconductor  
 scales                 1.1.1    2020-05-11 [1] CRAN (R 4.0.2)
 scater               * 1.18.0   2020-10-27 [1] Bioconductor  
 scran                * 1.18.0   2020-10-27 [1] Bioconductor  
 sctransform          * 0.3.1    2020-10-08 [1] CRAN (R 4.0.2)
 scuttle                1.0.0    2020-10-27 [1] Bioconductor  
 sessioninfo            1.1.1    2018-11-05 [1] CRAN (R 4.0.2)
 SingleCellExperiment * 1.12.0   2020-10-27 [1] Bioconductor  
 sparseMatrixStats      1.2.0    2020-10-27 [1] Bioconductor  
 statmod                1.4.35   2020-10-19 [1] CRAN (R 4.0.2)
 stringi                1.5.3    2020-09-09 [1] CRAN (R 4.0.2)
 stringr                1.4.0    2019-02-10 [1] CRAN (R 4.0.2)
 SummarizedExperiment * 1.20.0   2020-10-27 [1] Bioconductor  
 testthat               3.0.0    2020-10-31 [1] CRAN (R 4.0.2)
 tibble                 3.0.4    2020-10-12 [1] CRAN (R 4.0.2)
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 uwot                   0.1.8    2020-03-16 [1] CRAN (R 4.0.2)
 vctrs                  0.3.4    2020-08-29 [1] CRAN (R 4.0.2)
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 viridis                0.5.1    2018-03-29 [1] CRAN (R 4.0.2)
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 yaml                   2.2.1    2020-02-01 [1] CRAN (R 4.0.2)
 zlibbioc               1.36.0   2020-10-27 [1] Bioconductor  

[1] /mnt/mcscratch/rlyu/Software/R/4.0/library
[2] /opt/R/4.0.3/lib/R/library