msatcommander

msatcommander is a platform-independent Python program designed to automate the detection of microsatellite repeat arrays (SSR, VNTR) and streamline locus-specific primer design. By utilizing regular expression pattern matching and integrating Primer3 as its core engineering engine, it eliminates the bottleneck of manual sequence parsing. It accepts standard FASTA-formatted files and provides options for 5′-tailing (tagging) designed primers, exporting clean, spreadsheet-ready comma-separated value (CSV) outputs. System Requirements and Prerequisites

Before installation, ensure your environment meets the minimum configuration criteria:

Python Engine: Python 2.4 up to legacy Python 2.7 environment.

Core Modules: Biopython (v1.43+) and wxPython (v2.8+) for the graphical user interface (GUI). Design Engine: Primer3 executable binaries. Step-by-Step Installation Option A: Running from Source (All Platforms)

For Linux, modern macOS, and advanced environments, installing from the source repository provides the most control:

Clone the Repository: Use Git to pull the codebase directly from the official msatcommander GitHub repository.

git clone https://github.com/brantfaircloth/msatcommander.git cd msatcommander Use code with caution.

Configure Primer3 Paths: Locate the msatcommander.conf configuration file in the main directory. Open it in a text editor and specify the exact absolute path to your local primer3_core binary executable.

Launch the Interface: Run the main routing script to launch the GUI window. python main.py Use code with caution. Option B: Standalone Binary Bundles

If you are operating on older dedicated workstations running Windows XP or macOS 10.6+, you can bypass Python environment setups by downloading pre-compiled standalone application bundles via the msatcommander Google Code Archive. These bundles come with the embedded primer3_core binaries pre-built for your specific architecture. Standard Operational Workflow

[Input FASTA File] ➔ [Select Repeat Array Motifs] ➔ [Configure Primer3 Parameters] ➔ [Execute & Parse CSV] Step 1: Upload Input Sequences

Prepare your genomic data into standard single or concatenated, FASTA-formatted files (.fasta, .fa, or .fna). Click the Choose Input File button in the interface to load your dataset. Step 2: Define Microsatellite Search Parameters

Configure the regular expression engine to scan for target arrays:

Select individual repeat classes from mononucleotides up to hexanucleotides.

Establish strict cutoff thresholds by entering the minimum number of repetitions (e.g., setting a minimum of 5 repetitions for di-, tri-, and tetranucleotides).

Note: The tool automatically scans both the 5′–3′ orientation and its complement 3′–5′ orientation, identifying patterns by their lowest non-complementary alphabetical designation. Step 3: Configure Primer Design (Optional)

If you want to design flanking primers immediately after finding repeats, check the Design Primers checkbox. Adjust the fields to pass strict constraints to Primer3:

Product Size Range: Specify target amplicons, typically between 100 – 500 bp.

Melting Temperature ™: Set optimal primer Tm close to 60°C (with a min-max range of 57°C to 62°C).

Primer Composition: Aim for an optimal 50% GC content and add a 1 bp GC clamp to enhance binding stability.

5′-Tailing: If automated primer tagging is desired for multiplexing, check the primer-tail options to auto-apply standard CAG or M13R universal sequence tags to the 5′ end of your designed primers. Step 4: Execute and Analyze Outputs

Click Find Repeats / Design Primers to process the file. Once processing finishes, msatcommander generates structured, comma-separated .csv arrays:

Summary File: A comprehensive list charting every detected microsatellite motif locus, repeat count, and exact base pair coordinate.

Primers File: A detailed spreadsheet mapping the forward/reverse primer configurations, calculated Tm values, product lengths, and tailing metrics linked to each valid locus. To better tailor this article, please let me know:

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