burstInfer is a package designed for inferring single-cell transcriptional parameters (kon, koff, Pol II loading rate etc.) from MS2-MCP time series data, using an object-oriented Hidden Markov Model-based approach. Building upon earlier work by Lammers et al. (https://www.pnas.org/content/117/2/836), our model allows for scalable inference of transcriptional parameters for longer genes than the original model. Additionally, the model can be used to infer single-cell transcriptional parameters, allowing for modelling and visualisation of spatial gradients of transcriptional activity at single-cell resolution.
Examples included in the package outline how to process both synthetic and real Drosophila melanogaster data, train the model using Expectation Maximization and extract single-cell parameters.
Clone burstInfer repository:
git clone https://github.com/ManchesterBioinference/burstInfer.gitInstall:
cd burstInfer
pip install -r requirements.txt
python setup.py installSee requirements.txt for a list of required packages. library_versions_used.txt contains the package versions used while completing the model. There seems to be an issue with the current version of Numpy, so it's recommended to instead run:
cd burstInfer
pip install -r library_versions_used.txt
python setup.py installThree examples are included in the package - training the model using two synthetic genes and one experimental Drosophila dataset from Hoppe et al., Developmental Cell, 2020. These are included in the example_datasets folder in the main burstInfer folder.
Please see each of these folders for an explanation of what the examples do and which files to run.
| Folder Name | Description |
|---|---|
| synthetic_short_gene_example | Generate synthetic MS2 fluorescence traces using promoter sequences created using a Markov Process. These synthetic traces have been created while specifying a 'short' window size (5), making it possible to run the model on a laptop. Train the model, get the inferred parameters and use these to generate single cell parameters. Training takes less than 5 minutes. |
| synthetic_long_gene_example | As above, but with synthetic data generated using a longer window size (13). |
| hoppe_et_al_ush_real_data_example | Train the model using experimental MS2 data for the Drosophila gene ush, similar to that presented in Hoppe et al. |
Also in the example_datasets folder are scripts to reproduce two of the figures in the paper (model running time comparison and parameter convergence).
These are the core library files containing classes and functions used to train the model and generate parameters. Each of the example folders includes a main file which typically imports and processes MS2 data and then creates an instance of the HMM class, which uses some of these utility functions.
| File Name | Description |
|---|---|
| calcObservationLikelihood | Calculate HMM observation likelihood |
| calculate_single_cell_transition_rates | Given posterior transition probabilities, convert to transition rates |
| compute_dynamic_F | Get current compound state dynamically |
| exact_forward_backward | Exact version of forward backward (experimental) |
| export_em_parameters | Export inferred parameters as dataframe |
| forward_backward | Train model using forward-backward algorithm |
| get_adjusted | Get number of 1's and 0's in current compound state |
| get_posterior | Get posterior probabilities from trained model |
| get_single_cell_emission | Calculate single cell emission probabilities |
| HMM | HMM class, contains functions to run EM etc. |
| HMMnumba | More efficient version of HMM (experimental) |
| initialise_parameters | Initialise HMM parameters |
| log_sum_exp | Calculate log sum exp efficiently |
| logsumexp_numba | (Potentially) more efficient version of above |
| ms2_loading_coeff | Take fluorescence ramp-up during probe transit into account (similar to original model) |
| probe_adjustment | Run above |
| process_raw_data | Process MS2 data |
| v_log_solve | Calculate HMM emission parameter (similar to original model) |