Name: Video: Combining ilastik and Flynotyper for Accurate Detection and Quantification of Ommatidia in Drosophila melanogaster Fly Eye Images
Uploaded: 2024-10-04T14:35:00
Description: 159 Views. Combining ilastik and Flynotyper for Accurate Detection and Quantification of Ommatidia in Drosophila melanogaster Fly Eye Images

combining ilastik and flynotyper for accurate detection and quantification of ommatidia in drosophila melanogaster fly eye images

Unbiased Quantification of Ommatidia in Drosophila Eye Models

The Drosophila melanogaster genome contains ~75% of human disease-related gene orthologs. Additionally, during Drosophila eye development, approximately two-thirds of the genes in the genome are expressed, making the Drosophila eye an outstanding genetic system to investigate various molecular and cellular functions, development, and disease models1,2. Thus, the Drosophila eye system is a useful experimental tool to study various biological processes.
The Drosophila compound eye is a well-structured and comprehensive array of ~800 ommatidia that exhibit a symmetrical and hexagonal pattern3. The regularity of this hexagonal pattern can be used to estimate the effect of introducing mutations and gene expression changes in eye morphology4. Previous studies that require evaluation of eye morphology have heavily relied on manual ranking of the severity of eye phenotypes detected by the naked eye. To rank the eye phenotypes, external eye morphology images are taken by a stereomicroscope5,6. The eye phenotype of each group is assessed by splitting the external eye into four areas and calculating the proportion of degeneration in each area5,6. Then, the values are used to calculate averages that are compared with the values obtained from control flies7. The scoring is based on the extent of fusion, loss of ommatidia, and bristle organization7,8. Fly eye photos taken with a stereomicroscope are acquired by one researcher, and the eye phenotype analysis is performed by another researcher with triple validation sets7,8.
When it comes to ranking weak alterations in eye morphology with the naked eye, there are limitations4. To overcome these limitations, computational approaches such as FLEYE and Flynotyper have been developed1,9. Flynotyper is a novel computational method for quantitatively estimating morphological changes in the Drosophila eye system1. It automatically detects the Drosophila eye and individual ommatidium, calculating Phenotypic Scores (P-Scores) based on the irregularity of theeye1. A higher P-Score indicates the fly eye is more degenerated. This software was successfully used in quantifying the abnormality of Drosophila eyes10. Although Flynotyper ensures an automated process, it still cannot be successfully applied to some eye images taken by various light microscopy methods.
Qualitatively, we prefer a ring light source compared to a single-point light source, as it offers a more accurate representation of each ommatidium. However, when the ring light is used, it generates a ring-shaped shadow at the top of each ommatidium due to the hemispherical shape of the ommatidium. This ring-shaped shadow inhibits accurate ommatidial detection by Flynotyper, leading to incorrect calculation of P-Scores.
To overcome these issues, we implemented ilastik, a machine learning-based tool for various analyses, to classify ommatidia in fly eye images11. We then fed the ilastik-generated images into Flynotyper to calculate P-Scores. This allows us to quantify the Drosophila eye morphological defects unbiasedly1.

Author Spotlight: Quantifying Rough Eye Phenotypes in Drosophila Models of Amyotrophic Lateral Sclerosis with Frontotemporal Dementia

Quantifying Drosophila melanogaster Eye Phenotypes: A Computational Approach Integrating ilastik and Flynotyper

Combining ilastik and Flynotyper for Accurate Detection and Quantification of Ommatidia in Drosophila melanogaster Fly Eye Images

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Research

JoVE Journal

Developmental Biology

159 Views. Combining ilastik and Flynotyper for Accurate Detection and Quantification of Ommatidia in Drosophila melanogaster Fly Eye Images

Video: Combining ilastik and Flynotyper for Accurate Detection and Quantification of Ommatidia in  Drosophila melanogaster  Fly Eye Images

The Drosophila melanogaster compound eye is a well-structured and comprehensive array of around 800 ommatidia, exhibiting a symmetrical and hexagonal pattern. This regularity and ease of observation make the Drosophila eye system a powerful tool to model various human neurodegenerative diseases. However, ways of quantifying abnormal phenotypes, such as manual ranking of eye severity scores, have limitations, especially when ranking weak alterations in eye morphology. To overcome these limitations, computational approaches have been developed such as Flynotyper. The use of a ring light allows for better qualitative images accessing the intactness of individual ommatidia. However, these images cannot be analyzed by Flynotyper directly due to shadows on ommatidia introduced by the ring light. Here, we describe an unbiased way to quantify rough eye phenotypes observed in Drosophila disease models by combining two software, ilastik and Flynotyper. By preprocessing the images with ilastik, successful quantification of the rough eye phenotype can be achieved with Flynotyper.

The Drosophila eye system is a useful tool for studying various biological processes, particularly human neurodegenerative diseases. However, manual quantification of rough eye phenotypes can be biased and unreliable. Here we describe a method by which ilastik and Flynotyper are used to quantify eye phenotype in an unbiased way.

The Drosophila melanogaster compound eye is a well-structured and comprehensive array of around 800 ommatidia, exhibiting a symmetrical and hexagonal ...