The Multi-Omics Landscape: Genomics, Transcriptomics, Proteomics & Metabolomics
Biological systems operate through dynamic, multi-layered regulatory networks. Explore comprehensive guides, technologies, computational toolchains, and data architectures across every major omics discipline—from the genomic blueprint to the metabolic phenotype.
Functional & Regulatory Omics Workbench
Select an omic layer to inspect its end-to-end tool stack, statistical normalization model, and toy dataset.
🔄 The Central Dogma & The Hierarchy of Life
Each omics layer captures a unique phase in the flow of biological information. Combining these orthogonal dimensions provides an unprecedented systems-level view of health and disease:
Genomics (DNA)
What can happen: Static genetic code, germline mutations, somatic variants, and structural rearrangements.
Transcriptomics (RNA)
What appears to be happening: Dynamic gene expression levels, alternative splicing, non-coding RNAs, and single-cell states.
Proteomics (Proteins)
What is doing the work: Protein abundance, 3D structures, post-translational modifications (PTMs), and enzymatic complexes.
Metabolomics (Small Mol.)
What has actually happened: Cellular metabolites, biochemical pathway flux, lipids, sugars, and environmental readouts.
🧬 1. Genomics: Deciphering the DNA Blueprint
DNA • Variants • AssemblyGenomics investigates the complete genetic complement of an organism. Modern computational genomics revolves around high-throughput sequencing (NGS), aligning billions of short or long reads to human reference genomes (GRCh38, T2T-CHM13), and discovering genetic variations that govern disease, development, and evolution.
Sequencing Platforms
Illumina NovaSeq X (2×150 bp short reads, Q30+ accuracy), Pacific Biosciences (PacBio) HiFi long reads (15-20 kb, >99.9% accuracy), and Oxford Nanopore (ONT) ultra-long reads for resolving complex repeats and telomeres.
Compare NGS Technologies →Variant Discovery (SNVs, Indels, SVs)
Standardized alignment with BWA-MEM2 or Minimap2, coordinate sorting and duplicate marking with samtools, and variant calling using GATK HaplotypeCaller or Google DeepVariant.
Practical Genomics Track →De Novo Genome Assembly
Reconstructing complete chromosomal contigs using overlap-layout-consensus (OLC) or de Bruijn graphs (hifiasm, Flye, SPAdes) combined with optical mapping and Hi-C scaffolding.
Genome Assembly Guide →📊 2. Transcriptomics: Profiling the Expressed Genome
RNA-Seq • Single-Cell • SpatialTranscriptomics captures the quantity and identity of all RNA transcripts (mRNA, lncRNA, miRNA) active in a biological specimen at a given snapshot in time. It measures dynamic responses to environmental stimuli, drugs, and genetic perturbations.
Bulk RNA-Seq & Differential Expression
Splice-aware alignment with STAR or pseudo-alignment with Salmon/Kallisto. Negative binomial dispersion modeling and gene shrinkage with DESeq2 and edgeR in R.
Transcriptomics Guide →Single-Cell RNA-Seq (scRNA-seq)
Droplet microfluidics (10x Genomics Chromium) capturing single-cell transcriptomes with UMIs. Cellular heterogeneity clustering and trajectory modeling via Seurat and Scanpy.
Single-Cell Course (13 Ch) →Spatial Transcriptomics
Preserving the 2D architectural coordinates of gene expression in intact histology tissue sections using 10x Visium, Xenium In Situ, and NanoString CosMx.
Spatial Biology Module →🔬 3. Quantitative Proteomics: DIA / DDA & Phosphoproteomics
Mass Spec • 3D Structures • PTMsProteomics measures the ultimate functional machinery of the cell. Because post-transcriptional attenuation and protein degradation decouple mRNA expression from protein abundance, quantitative liquid chromatography tandem mass spectrometry (LC-MS/MS) provides direct insight into active signaling cascades, post-translational modifications (PTMs), and druggable target complexes.
Quantitative Proteomics Pipeline (DIA / DDA & Phosphoproteomics)
Raw Conversion & Peak Centroiding
Convert proprietary vendor files (.raw, .d) to open indexed centroided .mzML using ThermoRawFileParser or ProteoWizard msconvert.
Spectral Library & Quantification
DDA (LFQ/TMT): MSFragger + Philosopher + IonQuant.
DIA: Library-free deep learning in-silico spectral library prediction directly from FASTA proteome in DIA-NN.
QC & Hybrid Imputation
Filter reverse decoys and contaminants (cRAP), enforce ≥2 unique peptides, apply Variance Stabilizing Normalization (VSN), and impute left-censored MNAR values via MinProb / QRILC.
Differential Abundance
Linear modeling via MSstats or empirical Bayes moderated t-testing in limma / DEP (|log2FC| > 1, Benjamini-Hochberg FDR < 0.05).
Phospho & PPI Networks
Kinase-Substrate Enrichment Analysis via KSEAapp for phosphoproteomics and protein-protein interaction (PPI) network hub clustering via STRINGdb / Cytoscape.
# Convert all Thermo .raw files in directory to indexed centroided .mzML (-p = peak picking)
ThermoRawFileParser.sh -d ./raw_spectra/ -o ./mzml_centroided/ -f 2 -g -p# Step 2A: Generate in-silico predicted spectral library (.predicted.speclib) from FASTA
diann --lib "" --threads 32 --verbose 1 --out-lib reference_insilico.speclib --gen-spec-lib --predictor --fasta reference_proteome_canonical.fasta --fasta-search --min-fr-mz 200 --max-fr-mz 1800 --min-pep-len 7 --max-pep-len 30 --min-pr-mz 300 --max-pr-mz 1800 --min-pr-charge 1 --max-pr-charge 4 --cut K*,R* --missed-cleavages 1 --unimod4 --var-mods 1 --var-mod UniMod:35,15.994915,M
# Step 2B: Quantify samples against the predicted library with MBR (--reanalyse) & MaxLFQ
diann --f ./mzml_centroided/ctrl_01.mzML ./mzml_centroided/ctrl_02.mzML ./mzml_centroided/ctrl_03.mzML ./mzml_centroided/treat_01.mzML ./mzml_centroided/treat_02.mzML ./mzml_centroided/treat_03.mzML --lib reference_insilico.speclib.predicted.speclib --threads 32 --out diann_report.tsv --qvalue 0.01 --matrices --pg-level 1 --reanalyse --smart-profilingProtein.Group Genes Ctrl_1 Ctrl_2 Ctrl_3 Treat_1 Treat_2 Treat_3 Phospho_Site
P04637 TP53 2450000 2510000 2390000 8900000 9120000 8850000 S315-p
P38398 BRCA1 1820000 1790000 1850000 1950000 1880000 1910000 S1524-p
P00533 EGFR 6200000 6350000 6120000 1200000 1150000 1280000 Y1068-p
P42224 STAT1 3100000 2980000 3250000 7400000 7650000 7300000 Y701-p
P60709 ACTB 45000000 44500000 45800000 45200000 44800000 45100000 Unmodified
P04406 GAPDH 62000000 61800000 62500000 61900000 62200000 62100000 Unmodified# R Production Script: VSN Normalization, MinProb Imputation & Limma Differential Abundance
library(DEP)
library(dplyr)
library(SummarizedExperiment)
# 1. Load DIA-NN Protein Group Matrix & filter reverse decoys/contaminants
pg_raw <- read.delim("diann_report.pg_matrix.tsv", stringsAsFactors = FALSE, check.names = FALSE)
pg_clean <- pg_raw %>%
filter(!grepl("cRAP_|CON__|REV__", Protein.Group)) %>%
make_unique("Genes", "Protein.Group", delim = ";")
# 2. Experimental design table
exp_design <- data.frame(
label = c("ctrl_01", "ctrl_02", "ctrl_03", "treat_01", "treat_02", "treat_03"),
condition = c("Control", "Control", "Control", "Treated", "Treated", "Treated"),
replicate = c(1, 2, 3, 1, 2, 3)
)
# 3. Construct SummarizedExperiment & filter missing values
sample_cols <- which(colnames(pg_clean) %in% exp_design$label)
se <- make_se(pg_clean, sample_cols, exp_design)
se_filt <- filter_missval(se, thr = 1)
# 4. VSN Normalization & MinProb (q=0.01) left-censored MNAR imputation
se_norm <- normalize_vsn(se_filt)
se_imp <- impute(se_norm, fun = "MinProb", q = 0.01)
# 5. Empirical Bayes testing with limma
se_diff <- test_diff(se_imp, type = "control", control = "Control")
dep_res <- add_rejections(se_diff, alpha = 0.05, lfc = log2(2.0))
write.csv(get_results(dep_res), "proteomics_diff_results.csv", row.names = FALSE)# R Production Script: Kinase-Substrate Enrichment Analysis (KSEA)
library(KSEAapp)
# Input format: Protein, Gene, Peptide, Residue.Both (e.g. "S473"), p, FC
px_data <- read.csv("phospho_class1_sites_limma.csv")
# Infer upstream kinase z-scores using PhosphoSitePlus + NetworKIN
KSEA.Complete(
KSData = KSData,
PX = px_data,
NetworKIN = TRUE,
NetworKIN.cutoff = 5,
m.cutoff = 5,
p.cutoff = 0.05
)🧪 4. Untargeted Metabolomics: XCMS, MZmine 3 & GNPS
Small Molecules • OPLS-DA VIP • LipidsMetabolomics profiles the downstream metabolic flux resulting from genomic, transcriptomic, and environmental interactions. High-resolution liquid chromatography tandem mass spectrometry (LC-MS/MS) captures thousands of small molecules (<1500 Da), requiring sophisticated peak alignment, signal drift correction across pooled quality controls, and molecular networking.
Untargeted LC-MS/MS Metabolomics Pipeline
Centroiding & Peak Picking
Convert vendor files to centroided .mzML via msconvert. Execute XCMS4 CentWave peak detection (ppm = 15, peakwidth = c(5, 30)).
Alignment & Adduct Deconvolution
Align retention times using Obiwarp, group peak correspondence across sample classes, and deconvolute isotopes/adducts ([M+H]+, [M+Na]+) via CAMERA.
QC Drift & PQN Scaling
Blank subtraction (Sample/Blank > 3x), pooled QC LOESS drift correction (QC-RLSC), filter features by QC RSD < 20%, and apply Probabilistic Quotient Normalization (PQN) with Pareto scaling.
Multivariate Chemometrics
Unsupervised PCA (verifying QC cluster tightness) and supervised OPLS-DA with 1,000-permutation testing (R2Y, Q2) in ropls to extract VIP > 1.0 markers.
MS/MS Matching & Pathways
Structure prediction using SIRIUS 5 + CSI:FingerID, GNPS Feature-Based Molecular Networking (FBMN), and KEGG pathway topological impact enrichment.
# R Production Script: XCMS v4 Peak Picking, Alignment & MS2 Export for GNPS
library(xcms)
library(MsExperiment)
library(Spectra)
# 1. Load metadata & raw files
meta <- read.csv("lcms_injection_sequence.csv")
mse <- readMsExperiment(spectraFiles = meta$file_path, sampleData = meta)
# 2. CentWave Peak Detection
cwp <- CentWaveParam(ppm = 15, peakwidth = c(5, 30), snthresh = 10, prefilter = c(3, 5000), noise = 1000)
xdata <- findChromPeaks(mse, param = cwp)
# 3. Retention Time Alignment (Obiwarp) & Peak Density Correspondence
xdata <- adjustRtime(xdata, param = ObiwarpParam(binSize = 0.6))
pdp <- PeakDensityParam(sampleGroups = sampleData(xdata)$sample_group, minFraction = 0.70, bw = 5, binSize = 0.015)
xdata <- groupChromPeaks(xdata, param = pdp)
# 4. Fill Missing Peaks & Export Feature Matrix
xdata <- fillChromPeaks(xdata, param = ChromPeakAreaParam())
feature_mat <- featureValues(xdata, value = "into", method = "maxint")
feature_def <- as.data.frame(featureDefinitions(xdata))
write.csv(cbind(feature_def[, c("mzmed", "rtmed")], feature_mat), "xcms_raw_feature_table.csv")Feature_ID,mz,RT_min,Compound,QC_RSD,Ctrl_1,Ctrl_2,Ctrl_3,Dis_1,Dis_2,Dis_3,VIP
FT001,89.0238,1.25,L-Alanine,4.8,48200,47900,49100,51200,50800,51500,0.42
FT002,174.0401,3.42,cis-Aconitate,6.2,124000,121000,126000,38000,36500,39200,2.15
FT003,191.0192,4.81,Citric_Acid,5.1,310000,305000,318000,92000,89000,94500,2.41
FT004,117.0188,2.15,Succinic_Acid,7.4,85000,83000,86500,245000,251000,242000,2.08
FT005,146.0691,5.10,L-Glutamate,8.3,62000,60500,63000,185000,192000,181000,1.89
FT006,203.0531,1.88,D-Glucose,3.9,520000,515000,528000,518000,522000,519000,0.18library(pmp)
library(ropls)
# 1. Blank Subtraction & Pooled QC LOESS Drift Correction (QC-RLSC)
keep_blk <- rowMeans(feature_mat[, bio_idx], na.rm=TRUE) > (3 * rowMeans(feature_mat[, blank_idx], na.rm=TRUE))
mat_clean <- feature_mat[keep_blk, -blank_idx]
mat_corr <- QCRSC(df=mat_clean, order=meta_sub$injection_order, batch=rep(1, nrow(meta_sub)), classes=meta_sub$sample_group)
mat_filt <- filter_peaks_by_rsd(df=mat_corr, classes=meta_sub$sample_group, qc_label="QC", max_rsd=20)
# 2. kNN Imputation & Probabilistic Quotient Normalization (PQN)
mat_imp <- mv_imputation(mat_filt, method="knn")
mat_pqn <- pqn_normalisation(mat_imp, classes=meta_sub$sample_group, qc_label="QC")
# 3. Supervised OPLS-DA (Pareto Scaling, 1000 Permutations)
X_bio <- t(log2(mat_pqn[, bio_mask] + 1))
Y_bio <- factor(meta_sub$sample_group[bio_mask])
opls_mod <- opls(x=X_bio, y=Y_bio, predI=1, orthoI=NA, scaleC="pareto", permI=1000)
vip_scores <- getVipVn(opls_mod)
write.csv(data.frame(Feature=names(vip_scores), VIP=vip_scores), "oplsda_vip_features.csv")# Run SIRIUS + ZODIAC + CSI:FingerID + CANOPUS on exported MS2 .mgf spectra
sirius --input xcms_ms2_features.mgf --output ./sirius_project/ --max-mz 850 --cores 16 formula -p orbitrap --ppm-max 5 --candidates 10 zodiac fingerid --db BIO canopus write-summaries --output ./sirius_summaries/🧬 5. Epigenomics: WGBS/EM-Seq, ATAC-Seq & CUT&Tag
DNA Methylation • Chromatin • FootprintingEpigenomics reveals how identical genomic sequences produce divergent cellular phenotypes. By profiling 5-methylcytosine (5mC) CpG methylation, Tn5 transposase-accessible chromatin, and histone post-translational modifications, epigenomics uncovers active promoters, distant enhancers, and transcription factor occupancy across development and disease.
Epigenomics Pipeline (WGBS/EM-Seq Methylation, ATAC-Seq & CUT&Tag)
Trimming & Conversion QC
fastp adapter trimming and Bismark 3-letter alignment. Verify C-to-T non-conversion rate on unmethylated lambda phage or chloroplast spike-in controls (>99% conversion efficiency required).
Context Methylation & DMRs
Extract context-specific methylation (CpG, CHG, CHH) via bismark_methylation_extractor and call Differentially Methylated Regions (DMRs) using DSS beta-binomial models.
Chromatin Accessibility
ATAC-Seq: Shift Tn5 cut sites (+4 bp / -5 bp via alignmentSieve --ATACshift), filter fragments <100 bp, and call peaks with MACS3 --nomodel --shift -100 --extsize 200.
CUT&Tag: Sparse peak calling with SEACR normalized to IgG control.
Feature & Motif Footprinting
Annotate peak distribution relative to TSS (±3 kb) using ChIPseeker, generate TSS/TES matrix profiles with deepTools, and scan TF footprints with TOBIAS and HOMER findMotifsGenome.pl.
Chromatin-to-Expression
Multi-omics integration: Correlate promoter DMR hypomethylation and ATAC-Seq open chromatin peak gains with downstream gene upregulation in paired DESeq2 RNA-Seq datasets.
# 1. Prepare Bisulfite/EM-Seq Reference Index & Align Paired-End Reads
bismark_genome_preparation --bowtie2 --parallel 8 ./ref_genome_dir/
bismark --genome ./ref_genome_dir/ -1 R1.fq.gz -2 R2.fq.gz --parallel 4 -p 4 --output_dir ./bismark_aligned/
deduplicate_bismark --bam -p ./bismark_aligned/sample_bismark_bt2_pe.bam
# 2. Extract CpG/CHG/CHH Context Methylation Ratios
bismark_methylation_extractor --paired-end --no_overlap --comprehensive --bedGraph --CX_context --cytosine_report --genome_folder ./ref_genome_dir/ --parallel 8 sample_bismark_bt2_pe.deduplicated.bam# 1. Align with Bowtie2, remove chrM, and filter MAPQ >= 30
bowtie2 --very-sensitive -X 2000 -p 16 -x ref_index -1 atac_R1.fq.gz -2 atac_R2.fq.gz | samtools view -b -u -q 30 -F 1804 -f 2 - | samtools idxstats - | cut -f 1 | grep -v -E 'chrM|chrPt|Mt|Pt' | xargs samtools view -b raw.bam > atac_nuclear_filtered.bam
# 2. Shift Reads for Tn5 Cut-Site (+4 bp / -5 bp) & Call Peaks with MACS3
alignmentSieve --numberOfProcessors 16 --ATACshift --maxFragmentLength 100 --bam dedup.bam -o atac_NFR_shifted.bam
macs3 callpeak -t atac_NFR_shifted.bam -f BAM -g 2.7e9 -n sample_atac --nomodel --shift -100 --extsize 200 --keep-dup all -q 0.01
# 3. Bias-Corrected Transcription Factor Footprinting with TOBIAS
TOBIAS ATACorrect --bam atac_NFR_shifted.bam --genome ref.fa --peaks consensus_peaks.bed --outdir tobias_out --cores 16
TOBIAS ScoreBigwig --signal tobias_out/atac_NFR_shifted_corrected.bw --regions consensus_peaks.bed --output footprints.bw --cores 16
TOBIAS BINDetect --motifs JASPAR_motifs.meme --signals footprints.bw --genome ref.fa --peaks consensus_peaks.bed --outdir bindetect_out --cores 16# 1. Scale fragments by E. coli spike-in factor (10,000 / ecoli_reads)
SCALE_FACTOR=$(awk -v ecoli_reads=12500 'BEGIN {print 10000 / ecoli_reads}')
bedtools bamtobed -bedpe -i cutandtag_namesorted.bam | awk '$1==$4 && $6-$2 < 700 {print $1"\t"$2"\t"$6}' | sort -k1,1 -k2,2n > fragments.bed
bedtools genomecov -bg -scale "$SCALE_FACTOR" -i fragments.bed -g ref.chrom.sizes > sample_norm.bedgraph
# 2. Call Stringent Enriched Domains Against IgG Control with SEACR
bash SEACR_1.3.sh sample_norm.bedgraph igg_control_norm.bedgraph non stringent sample_cutandtag_seacrchr1 1002500 1003100 ATAC_Peak_001 450 . 8.42 12.5 9.8 320
chr1 1245000 1245800 ATAC_Peak_002 890 . 15.10 24.8 18.2 410
chr2 3205000 3205900 ATAC_Peak_003 320 . 5.80 8.1 6.4 510
chr3 8420000 8420700 ATAC_Peak_004 920 . 18.25 32.4 26.1 390
chr7 5515000 5516200 ATAC_Peak_005 1100 . 22.40 45.1 38.5 620
chr11 65280000 65280800 ATAC_Peak_006 780 . 12.90 19.5 15.4 400library(ChIPseeker)
library(TxDb.Hsapiens.UCSC.hg38.knownGene)
txdb <- TxDb.Hsapiens.UCSC.hg38.knownGene
# 1. Load atac_mini_peaks.narrowPeak & annotate relative to TSS (+/- 3kb)
peaks <- readPeakFile("atac_mini_peaks.narrowPeak")
peakAnno <- annotatePeak(peaks, tssRegion=c(-3000, 3000), TxDb=txdb)
print(as.data.frame(peakAnno)[, c("seqnames", "start", "end", "annotation", "distanceToTSS")])
# 2. Beta-Binomial DMR Calling with DSS
library(DSS)
# dml_test <- DMLtest(BSobj, group1 = c("C1", "C2"), group2 = c("T1", "T2"), smoothing = TRUE)
# dmrs <- callDMR(dml_test, delta = 0.20, p.threshold = 1e-4)🌱 6. Plant, Polyploid & Non-Model Genomics: Pangenomes, TEs & Crop GWAS
Wheat • EDTA • SubPhaser • Minigraph-CactusAgricultural crops and wild non-model plants represent the frontier of computational biology complexity. Species like allohexaploid bread wheat (Triticum aestivum, 16 Gb), polyploid sugarcane (10 Gb), and octoploid strawberry possess multi-subgenome architectures, extreme repeat densities (>80% retrotransposons), and rampant homoeologous exchange that break standard mammalian analysis pipelines.
Polyploid Phasing & Subgenomes
Resolve subgenome assemblies (A, B, D) without ancestral references using SubPhaser k-mer enrichment, PacBio HiFi string graphs in Hifiasm, and MCScan collinear synteny mapping.
EDTA De Novo TE Annotation
Structure-based identification of Ty1/Copia, Ty3/Gypsy, Helitrons, and TIR transposons using the EDTA pipeline, with LTR Assembly Index (LAI) validation to certify telomere-to-telomere continuity.
Crop Graph Pan-Genomics & GWAS
Capture dispensable crop resistance genes with Minigraph-Cactus variation graphs, and map complex quantitative traits with GEMMA mixed models accounting for breeding population structure.
Full Plant Track (13 Chapters) →🌐 7. Multi-Omics Data Integration & Machine Learning
Single-omics analyses only capture isolated slices of biological reality. Modern precision medicine increasingly relies on Multi-Omics Data Fusion—combining genomics (germline/somatic mutations), transcriptomics (expression), proteomics, and metabolomics into integrated statistical models.
Unsupervised Matrix Factorization (MOFA+)
Multi-Omics Factor Analysis identifies latent dimensions of variation that explain shared vs. assay-specific biological variance across heterogeneous sample cohorts.
Single-Cell Multi-Modal Assays
Assaying multiple molecular layers simultaneously from the exact same single cell: CITE-seq (RNA + cell-surface antibodies), 10x Multiome (RNA + ATAC accessibility).
Network Biology & Graph Neural Networks
Overlaying multi-omics signatures onto biological knowledge graphs (STRING protein-protein interactions, KEGG metabolic reactions) to discover robust clinical biomarkers.
📋 Master Omics Disciplines Comparison Matrix
Quick Reference| Omics Discipline | Target Molecule | Primary Technology | Core Data Formats | Standard Software Tools | Global Public Repository |
|---|---|---|---|---|---|
| Genomics | Nuclear / Mt DNA | Illumina, PacBio HiFi, ONT | FASTQ, BAM, VCF | BWA-MEM2, GATK4, DeepVariant | NCBI SRA, ENA |
| Transcriptomics | mRNA, lncRNA, miRNA | RNA-Seq, 10x Chromium, Visium | FASTQ, Counts, MTX | STAR, Salmon, DESeq2, Seurat | NCBI GEO, ArrayExpress |
| Proteomics | Proteins, Peptides, PTMs | LC-MS/MS, Cryo-EM, X-ray | RAW, mzML, PDB | MaxQuant, DIA-NN, AlphaFold 3 | PRIDE, ProteomeXchange, PDB |
| Metabolomics | Metabolites (<1.5 kDa) | LC-MS, GC-MS, NMR | mzML, netCDF, Peak tables | XCMS, MetaboAnalyst, GNPS | MetaboLights, Metabolomics Workbench |
| Epigenomics | 5mC DNA, Histones, Open Chromatin | WGBS, ATAC-seq, ChIP-seq | BAM, BigWig, narrowPeak | MACS3, Bismark, chromHMM | ENCODE Portal, GEO |
| Metagenomics | Microbial Community DNA | 16S Amplicon, Shotgun WMS | FASTQ, BIOM, FASTA (MAGs) | DADA2, QIIME 2, Kraken 2, CheckM | MG-RAST, NCBI SRA, ENA |