Working with Bioconductor objects

Author

Why use Bioconductor? From a user perspective, the answer is clear: because many statisticians, bioinformaticians, and computer scientists have spent time writing methods and algorithms specifically for biological/genomic data. A reason for this, and why many people have contributed to this project, is that there is a shared infrastructure for common data types. This infrastructure is built up of object classes. An example of a class is GRanges (stands for “genomic ranges”), which is a way to specify a set of ranges in a particular genome, e.g. from basepair 101 to basepair 200 on chromosome 1 of the human genome (version 38). What’s an object? Well everything in R is an object, but usually when we talk about Bioconductor objects, we mean data structures containing many attributes, so more complex than a vector or matrix. And the objects have specific methods that help you either access the information in the object, run analyses on the object, plot the object, etc. Bioconductor also allows for inheritance, which means that you can define a class of object that inherits the structure and methods of a superclass on which it depends. This last point is mostly important for people who are developing new software for Bioconductor (maybe that’s you!)

Getting started with Bioconductor

Before we get started, you need to know how to install Bioconductor packages. The most important details are:

  • Bioconductor is a package repository, like CRAN

  • All Bioconductor packages should be installed following the instructions here: https://bioconductor.org/install (the only real exception is if you want to obtain Linux binaries, but for working on Windows or Mac, you should stick to the above instructions)

  • Bioconductor packages are linked in their versions, both to each other and to the version of R

  • Bioconductor’s installation function will look up your version of R and give you the appropriate versions of Bioconductor packages

  • If you want the latest version of Bioconductor, you need to use the latest version of R

Our version of R/Bioconductor

We will be using this version of R and Bioconductor:

print(paste(
  "R version:",
  getRversion()
))
[1] "R version: 4.4.1"
print(paste(
  "Bioc version:",
  BiocManager::version()
))
[1] "Bioc version: 3.19"

How do you know if a package is a Bioconductor package? For one thing, you can just google the package name and you’ll see either CRAN or Bioconductor as a first result (packages must be in one or the other, they are not allowed to be on both repositories). But also, you can use Bioconductor’s installation function to install any packages, even ones on CRAN. By the way, you can install multiple packages at once by making a string vector: BiocManager::install(c("foo","bar"))

Why all this stress on versioning? This is because the packages in Bioconductor are highly interdependent, and also some are very dependent on R internals. So that the project can guarantee the code will run and not give errors on many systems (Linux, Mac and Windows have support for the majority of Bioconductor packages), new development is locked into cycles, such that a release of Bioconductor shouldn’t contain any two packages which conflict and could potentially cause errors.

Details: of course, Bioconductor is also a project, made up of people. There is a core team which is supported by an NIH grant, and developers who contribute to the open source Bioconductor packages. There are also yearly conferences (one in US, one in Europe, and one in Asia, etc.).

Working with Bioconductor objects

We will introduce the core Bioconductor objects this week. In this particular document, we will discuss one of the most important classes of object, which is the SummarizedExperiment, or SE.

SEs have the structure:

  • a matrix of data, rows are genomic features, and columns are samples
  • a table of data about the samples (columns)
  • a table of data about the features (rows)

A diagram of this 3-part structure can be found here.

In SE, the 3 parts of the object are called 1) assay, 2) colData and 3) rowData or rowRanges.

Note: There was a class of object that came before the SE, called the ExpressionSet, which was used primarily to store microarray data. Here we will skip over the ExpressionSet, and just look at SEs.

It helps to start by making a small toy SE, to see how the pieces come together. (Often you won’t make an SE manually, but it will be downloaded from an external source, or generated by a function that you call, e.g. tximeta or some other data loading function.)

library(SummarizedExperiment)
col_data <- data.frame(sample=factor(1:6),
                       condition=factor(c("A","A","B","B","C","C")),
                       treated=factor(rep(0:1,3)))
col_data
  sample condition treated
1      1         A       0
2      2         A       1
3      3         B       0
4      4         B       1
5      5         C       0
6      6         C       1

An important aspect of SEs is that the rows can optionally correspond to particular set of GRanges, e.g. a row of an SE could give the number of RNA-seq reads that can be assigned to a particular gene, and the row could also have metadata in the 3rd slot including, e.g. location of the gene in the genome. In this case, we use the rowRanges slot to specify the information.

If we don’t have ranges, we can just put a table on the “side” of the SE by specifying rowData.

I will show in the example though how to provide rowRanges. Let’s use the first 10 genes in the Ensembl database for human. The following code loads a database, pulls out all the genes (as GRanges), removes extra “non-standard” chromosomes, and then subsets to the first 10 genes.

library(EnsDb.Hsapiens.v86)
txdb <- EnsDb.Hsapiens.v86
g <- genes(txdb)
g <- keepStandardChromosomes(g, pruning.mode="coarse")
row_ranges <- g[1:10]

We will make up some simulated “expression” measurements, and then store these in the SE. I call list so I can name the matrix, otherwise it would not be named.

exprs <- matrix(rnorm(6 * 10), ncol=6, nrow=10)
se <- SummarizedExperiment(assay = list("exprs" = exprs),
                           colData = col_data,
                           rowRanges = row_ranges)
se
class: RangedSummarizedExperiment 
dim: 10 6 
metadata(0):
assays(1): exprs
rownames(10): ENSG00000223972 ENSG00000227232 ... ENSG00000238009 ENSG00000239945
rowData names(6): gene_id gene_name ... symbol entrezid
colnames: NULL
colData names(3): sample condition treated

We see this object has one named matrix. The object could have multiple matrices (as long as these are the same shape). In that case you could access the first with assay and in general by name, e.g. assay(se, "exprs") or equivalently assays(se)[["exprs"]] .

assayNames(se)
[1] "exprs"

Finally, if we wanted to add data onto the rows, for example, the score of a test on the matrix data, we use the metadata columns function, or mcols:

mcols(se)$score <- rnorm(10)
mcols(se)
DataFrame with 10 rows and 7 columns
                        gene_id    gene_name           gene_biotype seq_coord_system       symbol
                    <character>  <character>            <character>      <character>  <character>
ENSG00000223972 ENSG00000223972      DDX11L1 transcribed_unproces..       chromosome      DDX11L1
ENSG00000227232 ENSG00000227232       WASH7P unprocessed_pseudogene       chromosome       WASH7P
ENSG00000278267 ENSG00000278267    MIR6859-1                  miRNA       chromosome    MIR6859-1
ENSG00000243485 ENSG00000243485    MIR1302-2                lincRNA       chromosome    MIR1302-2
ENSG00000237613 ENSG00000237613      FAM138A                lincRNA       chromosome      FAM138A
ENSG00000268020 ENSG00000268020       OR4G4P unprocessed_pseudogene       chromosome       OR4G4P
ENSG00000240361 ENSG00000240361      OR4G11P unprocessed_pseudogene       chromosome      OR4G11P
ENSG00000186092 ENSG00000186092        OR4F5         protein_coding       chromosome        OR4F5
ENSG00000238009 ENSG00000238009 RP11-34P13.7                lincRNA       chromosome RP11-34P13.7
ENSG00000239945 ENSG00000239945 RP11-34P13.8                lincRNA       chromosome RP11-34P13.8
                                      entrezid      score
                                        <list>  <numeric>
ENSG00000223972 100287596,100287102,727856,...  1.9730464
ENSG00000227232                             NA  0.1291949
ENSG00000278267                      102466751 -0.5289888
ENSG00000243485            105376912,100302278  2.2268549
ENSG00000237613           654835,645520,641702  0.8103065
ENSG00000268020                             NA  0.4921381
ENSG00000240361                             NA  0.4040707
ENSG00000186092                          79501 -0.5600475
ENSG00000238009                             NA -0.5351076
ENSG00000239945                             NA -0.0423135

Adding data to the column metadata is even easier, we can just use $:

se$librarySize <- runif(6,1e6,2e6)
colData(se)
DataFrame with 6 rows and 4 columns
    sample condition  treated librarySize
  <factor>  <factor> <factor>   <numeric>
1        1         A        0     1248412
2        2         A        1     1373904
3        3         B        0     1294192
4        4         B        1     1085109
5        5         C        0     1379352
6        6         C        1     1736940

Using the ranges of a SE

How does this additional functionality of the rowRanges facilitate faster data analysis? Suppose we are working with another data set besides se and we find a region of interest on chromsome 1. If we want to pull out the expression data for that region, we just ask for the subset of se that overlaps. First we build the query region, and then use the GRanges function overlapsAny within single square brackets (like you would subset any matrix-like object:

query <- GRanges("1", IRanges(25000,40000))
se_sub <- se[overlapsAny(se, query), ]

We could have equivalently used the shorthand code:

se_sub <- se[se %over% query,]

We get just three ranges, and three rows of the SE:

rowRanges(se_sub)
GRanges object with 3 ranges and 7 metadata columns:
                  seqnames      ranges strand |         gene_id   gene_name           gene_biotype
                     <Rle>   <IRanges>  <Rle> |     <character> <character>            <character>
  ENSG00000227232        1 14404-29570      - | ENSG00000227232      WASH7P unprocessed_pseudogene
  ENSG00000243485        1 29554-31109      + | ENSG00000243485   MIR1302-2                lincRNA
  ENSG00000237613        1 34554-36081      - | ENSG00000237613     FAM138A                lincRNA
                  seq_coord_system      symbol             entrezid     score
                       <character> <character>               <list> <numeric>
  ENSG00000227232       chromosome      WASH7P                 <NA>  0.129195
  ENSG00000243485       chromosome   MIR1302-2  105376912,100302278  2.226855
  ENSG00000237613       chromosome     FAM138A 654835,645520,641702  0.810306
  -------
  seqinfo: 25 sequences (1 circular) from GRCh38 genome
assay(se_sub)
                      [,1]       [,2]       [,3]       [,4]       [,5]        [,6]
ENSG00000227232 0.01177498  0.7065556 -0.7990868  1.7106496 -0.4288469  0.08066612
ENSG00000243485 2.19473151  0.1343476  1.3064152 -0.6255965  0.8216205 -0.40464210
ENSG00000237613 0.04944803 -0.2982052 -0.4527754  1.9442470  0.1513793  1.38634779

Another useful property is that we know metadata about the chromosomes, and the version of the genome. (If you were not yet aware, the basepair position of a given feature, say gene XYZ, will change between versions of the genome, as sequences are added or rearranged.)

seqinfo(se)
Seqinfo object with 25 sequences (1 circular) from GRCh38 genome:
  seqnames seqlengths isCircular genome
  1         248956422      FALSE GRCh38
  10        133797422      FALSE GRCh38
  11        135086622      FALSE GRCh38
  12        133275309      FALSE GRCh38
  13        114364328      FALSE GRCh38
  ...             ...        ...    ...
  8         145138636      FALSE GRCh38
  9         138394717      FALSE GRCh38
  MT            16569       TRUE GRCh38
  X         156040895      FALSE GRCh38
  Y          57227415      FALSE GRCh38

Downloading SE data

We previously introduced the computational project, called recount2, which performs a basic summarization of public data sets with gene expression data. We will use data from recount2 again.

This dataset contains RNA-seq samples from human airway epithelial cell cultures. The paper is here. The structure of the experiment was that, cell cultures from 6 asthmatic and 6 non-asthmatics donors were treated with viral infection or left untreated (controls). So we have 2 samples (control or treated) for each of the 12 donors.

library(here)
here() starts at /Users/milove/teach/compbio/compbio_src
url <- "http://duffel.rail.bio/recount/SRP046226/rse_gene.Rdata"
file <- here("bioc","asthma.rda")
if (!file.exists(file)) download.file(url, file)
load(file)

We use a custom function to produce a matrix which a count of RNA fragments for each gene (rows) and each sample (columns).

(Recount project calls these objects rse for RangedSummarizedExperiment, meaning it has rowRanges information.)

source(here("bioc","my_scale_counts.R"))
rse <- my_scale_counts(rse_gene)

We can take a peek at the column data:

colData(rse)[,1:6]
DataFrame with 24 rows and 6 columns
               project      sample  experiment         run read_count_as_reported_by_sra
           <character> <character> <character> <character>                     <integer>
SRR1565926   SRP046226   SRS694613   SRX692912  SRR1565926                      12866750
SRR1565927   SRP046226   SRS694614   SRX692913  SRR1565927                      12797108
SRR1565928   SRP046226   SRS694615   SRX692914  SRR1565928                      13319016
SRR1565929   SRP046226   SRS694616   SRX692915  SRR1565929                      13725752
SRR1565930   SRP046226   SRS694617   SRX692916  SRR1565930                      10882416
...                ...         ...         ...         ...                           ...
SRR1565945   SRP046226   SRS694632   SRX692931  SRR1565945                      13791854
SRR1565946   SRP046226   SRS694633   SRX692932  SRR1565946                      13480842
SRR1565947   SRP046226   SRS694634   SRX692933  SRR1565947                      13166594
SRR1565948   SRP046226   SRS694635   SRX692934  SRR1565948                      13320398
SRR1565949   SRP046226   SRS694636   SRX692935  SRR1565949                      13002276
           reads_downloaded
                  <integer>
SRR1565926         12866750
SRR1565927         12797108
SRR1565928         13319016
SRR1565929         13725752
SRR1565930         10882416
...                     ...
SRR1565945         13791854
SRR1565946         13480842
SRR1565947         13166594
SRR1565948         13320398
SRR1565949         13002276

The information we are interested in is contained in the characteristics column (which is a character list).

class(rse$characteristics)
[1] "CompressedCharacterList"
attr(,"package")
[1] "IRanges"
rse$characteristics[1:3]
CharacterList of length 3
[[1]] cell type: Isolated from human trachea-bronchial tissues passages: 2 disease state: asthmatic treatment: HRV16
[[2]] cell type: Isolated from human trachea-bronchial tissues passages: 2 disease state: asthmatic treatment: HRV16
[[3]] cell type: Isolated from human trachea-bronchial tissues passages: 2 disease state: asthmatic treatment: HRV16
rse$characteristics[[1]]
[1] "cell type: Isolated from human trachea-bronchial tissues"
[2] "passages: 2"                                             
[3] "disease state: asthmatic"                                
[4] "treatment: HRV16"                                        

We can pull out the 3 and 4 element using the sapply function and the square bracket function. I know this syntax looks a little funny, but it’s really just saying, use the single square bracket, pull out the third element (or fourth element).

rse$condition <- sapply(rse$characteristics, `[`, 3)
rse$treatment <- sapply(rse$characteristics, `[`, 4)
table(rse$condition, rse$treatment)
                              
                               treatment: HRV16 treatment: Vehicle
  disease state: asthmatic                    6                  6
  disease state: non-asthmatic                6                  6

Let’s see what the rowRanges of this experiment look like:

rowRanges(rse)
GRanges object with 58037 ranges and 3 metadata columns:
                     seqnames              ranges strand |            gene_id bp_length
                        <Rle>           <IRanges>  <Rle> |        <character> <integer>
  ENSG00000000003.14     chrX 100627109-100639991      - | ENSG00000000003.14      4535
   ENSG00000000005.5     chrX 100584802-100599885      + |  ENSG00000000005.5      1610
  ENSG00000000419.12    chr20   50934867-50958555      - | ENSG00000000419.12      1207
  ENSG00000000457.13     chr1 169849631-169894267      - | ENSG00000000457.13      6883
  ENSG00000000460.16     chr1 169662007-169854080      + | ENSG00000000460.16      5967
                 ...      ...                 ...    ... .                ...       ...
   ENSG00000283695.1    chr19   52865369-52865429      - |  ENSG00000283695.1        61
   ENSG00000283696.1     chr1 161399409-161422424      + |  ENSG00000283696.1       997
   ENSG00000283697.1     chrX 149548210-149549852      - |  ENSG00000283697.1      1184
   ENSG00000283698.1     chr2 112439312-112469687      - |  ENSG00000283698.1       940
   ENSG00000283699.1    chr10   12653138-12653197      - |  ENSG00000283699.1        60
                              symbol
                     <CharacterList>
  ENSG00000000003.14          TSPAN6
   ENSG00000000005.5            TNMD
  ENSG00000000419.12            DPM1
  ENSG00000000457.13           SCYL3
  ENSG00000000460.16        C1orf112
                 ...             ...
   ENSG00000283695.1            <NA>
   ENSG00000283696.1            <NA>
   ENSG00000283697.1    LOC101928917
   ENSG00000283698.1            <NA>
   ENSG00000283699.1         MIR4481
  -------
  seqinfo: 25 sequences (1 circular) from an unspecified genome; no seqlengths
seqinfo(rse)
Seqinfo object with 25 sequences (1 circular) from an unspecified genome; no seqlengths:
  seqnames seqlengths isCircular genome
  chr1           <NA>       <NA>   <NA>
  chr2           <NA>       <NA>   <NA>
  chr3           <NA>       <NA>   <NA>
  chr4           <NA>       <NA>   <NA>
  chr5           <NA>       <NA>   <NA>
  ...             ...        ...    ...
  chr21          <NA>       <NA>   <NA>
  chr22          <NA>       <NA>   <NA>
  chrX           <NA>       <NA>   <NA>
  chrY           <NA>       <NA>   <NA>
  chrM           <NA>       TRUE   <NA>

The rowRanges here were determined by the quantification method that the recount2 authors used. We don’t know what the genome is from the seqinfo, but we could look this up from the project website.

The following code I use to clean up the condition and treatment variables:

library(magrittr)
rse$condition %<>% (function(x) {
  factor(sub("-",".", sub("disease state: (.*)","\\1",x) ))
  })
rse$treatment %<>% (function(x) factor(sub("treatment: (.*)","\\1",x)))

Now we have:

table(rse$condition, rse$treatment)
               
                HRV16 Vehicle
  asthmatic         6       6
  non.asthmatic     6       6

Visualizing count matrix data in a SE

We will discuss transformations and normalization in a following section, but here we will just use a transformation so that we can compute meaningful distances on count data. We build a DESeqDataSet and then specify the experimental design using a ~ and the variables that we expect to produce differences in the counts. (These variables are used to assess how much technical variability is in the data, but not used in the transformation function itself.)

library(DESeq2)
dds <- DESeqDataSet(rse, ~condition + treatment)
converting counts to integer mode

We use this function, which implements a variance stabilizing transformation (more on this next time):

vsd <- vst(dds)

We calculate the variance across all samples (on the transformed data):

library(matrixStats)
rv <- rowVars(assay(vsd))
o <- order(rv, decreasing=TRUE)[1:100]

Finally, before plotting a heatmap, we extract the covariates that we want to annotated the top of the plot.

anno_col <- as.data.frame(colData(vsd)[,c("condition","treatment")])
anno_col
               condition treatment
SRR1565926     asthmatic     HRV16
SRR1565927     asthmatic     HRV16
SRR1565928     asthmatic     HRV16
SRR1565929     asthmatic     HRV16
SRR1565930     asthmatic     HRV16
SRR1565931     asthmatic     HRV16
SRR1565932     asthmatic   Vehicle
SRR1565933     asthmatic   Vehicle
SRR1565934     asthmatic   Vehicle
SRR1565935     asthmatic   Vehicle
SRR1565936     asthmatic   Vehicle
SRR1565937     asthmatic   Vehicle
SRR1565938 non.asthmatic     HRV16
SRR1565939 non.asthmatic     HRV16
SRR1565940 non.asthmatic     HRV16
SRR1565941 non.asthmatic     HRV16
SRR1565942 non.asthmatic     HRV16
SRR1565943 non.asthmatic     HRV16
SRR1565944 non.asthmatic   Vehicle
SRR1565945 non.asthmatic   Vehicle
SRR1565946 non.asthmatic   Vehicle
SRR1565947 non.asthmatic   Vehicle
SRR1565948 non.asthmatic   Vehicle
SRR1565949 non.asthmatic   Vehicle

This code pull out the top of the transformed data by variance, and adds an annotation to the top of the plot. By default the rows and columns will be clustered by Euclidean distance. See ?pheatmap for more details on this function (it’s a very detailed manual page).

library(pheatmap)
pheatmap(assay(vsd)[o,],
         annotation_col=anno_col,
         show_rownames=FALSE, 
         show_colnames=FALSE)

We can also easily make a PCA plot with dedicated functions:

plotPCA(vsd, intgroup="treatment")
using ntop=500 top features by variance

SingleCellExperiment

An example of a class that extends the SE is SingleCellExperiment. This is a special object type for looking at single cell data.

For more details, there is a free online book “Orchestrating Single Cell Analysis With Bioconductor” produced by a group within the Bioconductor Project, with lots of example analyses: OSCA.

Here we show a quick example of how this object extends the SE.

library(SingleCellExperiment)
sce <- as(rse, "SingleCellExperiment")
sce
class: SingleCellExperiment 
dim: 58037 24 
metadata(0):
assays(1): counts
rownames(58037): ENSG00000000003.14 ENSG00000000005.5 ... ENSG00000283698.1
  ENSG00000283699.1
rowData names(3): gene_id bp_length symbol
colnames(24): SRR1565926 SRR1565927 ... SRR1565948 SRR1565949
colData names(23): project sample ... condition treatment
reducedDimNames(0):
mainExpName: NULL
altExpNames(0):

There are special functions dedicated to scaling the samples (we will discuss this technical aspect soon):

library(scran)
Loading required package: scuttle
sce <- computeSumFactors(sce)
sizeFactors(sce)
 [1] 0.7672143 0.8205514 0.8686567 0.9479224 0.6484723 0.9815079 1.0797070 1.0569889 1.4377886
[10] 0.9465292 1.4759422 1.2630195 0.8889808 1.0524670 0.9677885 0.8086102 0.8806503 0.8999780
[19] 0.9505805 1.0430322 1.2527967 0.9908707 0.5208294 1.4491155

Similarly, dedicated functions for transformations:

sce <- logNormCounts(sce)
assayNames(sce)
[1] "counts"    "logcounts"

And dedicated functions and new slots for reduced dimensions:

set.seed(1)
sce <- fixedPCA(sce, rank=5, subset.row=NULL)
reducedDimNames(sce)
[1] "PCA"

We can manually get at the PCs:

pca <- reducedDim(sce, "PCA")
plot(pca[,1:2])

But we can more easily use dedicated visualization functions:

library(scater)
plotReducedDim(sce, "PCA", color_by="treatment")

Other specialized objects in Bioconductor

Some other specialized objects that build on the SummarizedExperiment include:

  • SpatialExperiment1 with best practices outlined here
  • QFeatures2 for high-throughput mass spectrometry
  • MultiAssayExperiment3 for multiple experimental assays performed on an overlapping set of specimens, e.g. RNA-seq, copy number, DNA methylation, etc.
  • MethylationArray4 for DNA methylation arrays
  • TreeSummarizedExperiment5 for data with hierarchical or tree-like structure on the rows or columns
sessionInfo()
R version 4.4.1 (2024-06-14)
Platform: aarch64-apple-darwin20
Running under: macOS Sonoma 14.4.1

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/lib/libRblas.0.dylib 
LAPACK: /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.0

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

time zone: America/New_York
tzcode source: internal

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

other attached packages:
 [1] scater_1.32.1               ggplot2_3.5.1               scran_1.32.0               
 [4] scuttle_1.14.0              SingleCellExperiment_1.26.0 pheatmap_1.0.12            
 [7] DESeq2_1.44.0               magrittr_2.0.3              here_1.0.1                 
[10] EnsDb.Hsapiens.v86_2.99.0   ensembldb_2.28.0            AnnotationFilter_1.28.0    
[13] GenomicFeatures_1.56.0      AnnotationDbi_1.66.0        SummarizedExperiment_1.34.0
[16] Biobase_2.64.0              GenomicRanges_1.56.1        GenomeInfoDb_1.40.1        
[19] IRanges_2.38.1              S4Vectors_0.42.1            BiocGenerics_0.50.0        
[22] MatrixGenerics_1.16.0       matrixStats_1.3.0           testthat_3.2.1.1           
[25] rmarkdown_2.27              devtools_2.4.5              usethis_3.0.0              

loaded via a namespace (and not attached):
  [1] RColorBrewer_1.1-3        rstudioapi_0.16.0         jsonlite_1.8.8           
  [4] ggbeeswarm_0.7.2          farver_2.1.2              fs_1.6.4                 
  [7] BiocIO_1.14.0             zlibbioc_1.50.0           vctrs_0.6.5              
 [10] memoise_2.0.1             Rsamtools_2.20.0          DelayedMatrixStats_1.26.0
 [13] RCurl_1.98-1.16           htmltools_0.5.8.1         S4Arrays_1.4.1           
 [16] curl_5.2.1                BiocNeighbors_1.22.0      SparseArray_1.4.8        
 [19] htmlwidgets_1.6.4         cachem_1.1.0              GenomicAlignments_1.40.0 
 [22] igraph_2.0.3              mime_0.12                 lifecycle_1.0.4          
 [25] pkgconfig_2.0.3           rsvd_1.0.5                Matrix_1.7-0             
 [28] R6_2.5.1                  fastmap_1.2.0             GenomeInfoDbData_1.2.12  
 [31] shiny_1.9.1               digest_0.6.36             colorspace_2.1-1         
 [34] rprojroot_2.0.4           dqrng_0.4.1               irlba_2.3.5.1            
 [37] pkgload_1.4.0             RSQLite_2.3.7             beachmat_2.20.0          
 [40] labeling_0.4.3            fansi_1.0.6               httr_1.4.7               
 [43] abind_1.4-5               compiler_4.4.1            remotes_2.5.0            
 [46] bit64_4.0.5               withr_3.0.1               BiocParallel_1.38.0      
 [49] viridis_0.6.5             DBI_1.2.3                 pkgbuild_1.4.4           
 [52] DelayedArray_0.30.1       sessioninfo_1.2.2         bluster_1.14.0           
 [55] rjson_0.2.21              tools_4.4.1               vipor_0.4.7              
 [58] beeswarm_0.4.0            httpuv_1.6.15             glue_1.7.0               
 [61] restfulr_0.0.15           promises_1.3.0            grid_4.4.1               
 [64] cluster_2.1.6             generics_0.1.3            gtable_0.3.5             
 [67] metapod_1.12.0            BiocSingular_1.20.0       ScaledMatrix_1.12.0      
 [70] utf8_1.2.4                XVector_0.44.0            ggrepel_0.9.5            
 [73] pillar_1.9.0              stringr_1.5.1             limma_3.60.4             
 [76] later_1.3.2               dplyr_1.1.4               lattice_0.22-6           
 [79] rtracklayer_1.64.0        bit_4.0.5                 tidyselect_1.2.1         
 [82] locfit_1.5-9.10           Biostrings_2.72.1         miniUI_0.1.1.1           
 [85] knitr_1.48                gridExtra_2.3             ProtGenerics_1.36.0      
 [88] edgeR_4.2.1               xfun_0.46                 statmod_1.5.0            
 [91] brio_1.1.5                stringi_1.8.4             UCSC.utils_1.0.0         
 [94] lazyeval_0.2.2            yaml_2.3.10               evaluate_0.24.0          
 [97] codetools_0.2-20          tibble_3.2.1              BiocManager_1.30.23      
[100] cli_3.6.3                 xtable_1.8-4              munsell_0.5.1            
[103] Rcpp_1.0.13               png_0.1-8                 XML_3.99-0.17            
[106] parallel_4.4.1            ellipsis_0.3.2            blob_1.2.4               
[109] profvis_0.3.8             urlchecker_1.0.1          sparseMatrixStats_1.16.0 
[112] bitops_1.0-8              viridisLite_0.4.2         scales_1.3.0             
[115] purrr_1.0.2               crayon_1.5.3              rlang_1.1.4              
[118] cowplot_1.1.3             KEGGREST_1.44.1