Application on MOCA 100k

Alexis Vandenbon & Diego Diez

2022-11-09

Load data

Here we apply haystack to 100k cells from the Mouse Organogenesis Cell Atlas (MOCA). The sparse matrix data was downloaded from the MOCA website. The data was converted into a Seurat object and processed following the standard pipeline.

library(here)
library(Seurat)
library(singleCellHaystack)

x <- readRDS(here("data-raw/data/moca_100k.rds"))
x

## An object of class Seurat 
## 16811 features across 100000 samples within 1 assay 
## Active assay: RNA (16811 features, 2000 variable features)
##  2 dimensional reductions calculated: pca, umap

DimPlot(x, label = TRUE) + NoLegend() + NoAxes()

Haystack

We run haystack using PCA coordinates with 50 PCs.

system.time({
  res <- haystack(x, coord="pca")
})

##    user  system elapsed 
## 256.045  28.569 284.612

It takes around 5 minutes to complete in a standard personal computer. Here we show the top 10 genes selected by haystack.

top <- show_result_haystack(res)
head(top, n=10)

##               D_KL log.p.vals log.p.adj
## Ppp1r1c 0.25684566  -202.6767 -198.4511
## Acp5    0.13324559  -173.9745 -169.7489
## Itih2   0.19905815  -168.2541 -164.0285
## A1cf    0.27878610  -161.4285 -157.2029
## Kel     0.08720005  -158.6047 -154.3791
## Rhag    0.08512571  -157.6347 -153.4091
## Ermap   0.08432139  -157.2455 -153.0199
## Pkhd1l1 0.09157942  -156.9557 -152.7301
## Spta1   0.08178285  -155.5603 -151.3347
## Gm43449 0.16349201  -155.3943 -151.1687

And here we plot the expression of the top 4 genes.

FeaturePlot(x, head(rownames(top), 4), order=TRUE) & NoAxes()