Molecular Techniques for Avian Sex Identification

The determination of avian sex by molecular methods exploits differences between the Z and W sex chromosomes, most notably variants of the chromo-helicase-DNA-binding (CHD) gene. Conventional polymerase chain reaction (PCR) assays using universal primer pairs (such as P2/P8 or CHD1F/CHD1R) remain the foundation of laboratory sexing, with products visualised by gel electrophoresis or melting-curve analysis. Recent innovations aim to simplify, expedite and decentralise the workflow by integrating isothermal amplification and lateral-flow or immunochromatographic detection. Techniques such as loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA) and cross-priming amplification (CPA) allow rapid, equipment-minimal assays suitable for point-of-care or field application. Quantitative PCR (qPCR) protocols further enhance sensitivity, enable melt-curve discrimination and permit high-throughput processing. Collectively, these molecular approaches underpin applications in conservation breeding, ecological research, pest management and the poultry industry, offering non-invasive sampling, high accuracy and rapid turnaround times for a wide range of avian taxa.

Research from Nature Portfolio

Recent studies have refined qPCR-based sexing in monomorphic species by evaluating intronic targets within the CHD1 gene. In one investigation of the Eurasian pygmy owl, researchers compared three primer pairs in a large cohort of blood samples, combining melt-curve analysis with gel electrophoresis to assess reliability. Only the CHD1F/CHD1R primer set yielded clear male and female profiles via single and dual peaks, respectively, on the melt curves and consistent banding patterns on agarose gels. This work underscores the importance of primer choice and the integration of melt-curve analysis for robust laboratory sex typing in species with minimal size differences between CHD-Z and CHD-W amplicons.

Molecular Techniques for Avian Sex Identification publication trend

The graph below shows the total number of articles in molecular techniques for avian sex identification across all publications each year (not limited to Nature Index journals).

Technical terms

Chromo-helicase-DNA-binding (CHD) gene: A sex-linked gene with Z and W alleles used as a universal marker for bird sexing.

Polymerase chain reaction (PCR): An enzymatic method to amplify specific DNA sequences for subsequent detection.

Quantitative PCR (qPCR): PCR with real-time fluorescence measurement, often combined with melt-curve analysis to distinguish amplicon variants.

Loop-mediated isothermal amplification (LAMP): An isothermal DNA amplification technique that uses multiple primers and a strand-displacing polymerase for rapid detection without thermal cycling.

Recombinase polymerase amplification (RPA): An isothermal method employing recombinase and strand-displacement enzymes to amplify DNA at constant temperature.

Cross-priming amplification (CPA): An isothermal amplification strategy using primer pairs that facilitate rapid, specific DNA replication without thermal cycling.

Melting-curve analysis: A post-PCR method that monitors fluorescence changes as double-stranded DNA amplicons dissociate, allowing discrimination of sequence variants.

Electrophoresis: A technique for separating DNA fragments by size through a gel matrix under an electric field.

Lateral-flow dipstick (LFD) / immune-chromatographic strip: A paper-based device that captures labelled amplicons to produce a visible test line, enabling instrument-free detection.

References

1. An approach to rapidly identify the gender of the pigeon by using cross-priming amplification with immune-chromatographic strip. Talanta (2023).
2. Comparison of three primer pairs for molecular sex determination in Eurasian pygmy owls (Glaucidium passerinum). Scientific Reports (2024).
3. Application of Loop-Mediated Isothermal Amplification (LAMP) in Sex Identification of Parrots Bred in Egypt. Biology (2022).
4. Development of a Rapid Sex Identification Method for Newborn Pigeons Using Recombinase Polymerase Amplification and a Lateral-Flow Dipstick on Farm. Animals (2022).