How were drosophila’s entire lives? – A powerful tool for detecting the individual fly history throughout the life –

Significance 

Animals, including humans, develop through a sequence of events and stages. For example, embryogenesis starts with egg fertilization, the embryo transitions through the juvenile stage, and this it lasts through the lifetime in which an animal grows and develops until it dies. The timing of each developmental stage is affected by genetics and several environmental factors. Therefore, developmental timing could be described as a phenotype. Determining developmental timings accurately could help understand the physiological and molecular bases of biological stages and events. It could also help unearth new factors influencing organisms’ development and lifespan.

That said, it’s quite challenging to accurately determine the developmental transitions of most organisms. One reason for this is that in many cases there are no clear distinctions between an organism’s life stages. This challenge has made it impractical to employ developmental timings in developmental biology investigations.

However, holometabolous insets, for example, the fruit fly Drosophila melanogaster have distinctive life stages namely: embryo, larva, pupa, and adult. These developmental transitions come with momentous biological and morphological changes such as hatching, pupariation, eclosion, and death. As a result, it possible to accurately determine the time point of each developmental stage making Drosophila desirable model for studying genetics and developmental biology.

Unfortunately, manual methods are being used in the determination of Drosophila’s developmental transitions, and no significant improvements have been made. Manual determination comes with several drawbacks including intensive labor required in improving the temporal resolution, which consequently hampers the determination of subtle changes in the transition time for each event. Also, manual counting isn’t practical or feasible for high throughput screening and in identifying multiple phonotypes in each fly’s transition events. On the flip side, it could help make clear the linkages between developmental transitions and the various environmental factors affecting them. Video cameras have been fronted as a vital tool in measuring developmental timings, but this also is labor-intensive, inappropriate for high-throughput analyses, and requires a longer analytical period to make an accurate determination.

A team of researchers: Dr. Ki-Hyeon Seong, Dr. Taishi Matsumura, Dr. Yuko Shimada-Niwa, Dr. Ryusuke Niwa, and Dr. Siu Kang from RIKEN Tsukuba Institute in Japan, developed an innovative Drosophila Individual Activity Monitoring and Detection System (DIAMonDS) equipped with time-lapse imaging, an algorithm, and a web application. The new system was intended to automatically determine several fruit flies ‘ transition time points such as pupariation, eclosion, and death. The system automatically and sequentially determined the transition time points of the various life cycle stages at high temporal resolution and on a large scale. The original research article is currently published in the journal, eLife.

A single fly was placed in each well of a microplate, time-lapse images were acquired, and the output analyzed using the system’s novel algorithm Sapphire. Time-lapse imaging implemented a basic flatbed charge-coupled device scanner.

DIAMonDS automatically and sequentially detected developmental time points from time-lapse images. The findings were that, compared to manual detection, DIAMonDS accurately detected 74-85% of the fruit fly’s pupariation and eclosion and approximately 92% of death events in just 10 frames. The system could also analyze the linkages between stages by multiple life events of several individuals sequentially. It also removed the constraint of long data acquisition and analysis time intervals, enabled high-resolution throughput analysis, and enabled a simultaneous operation of multiple scanners. Put simply, DIAMonDS could go a long way in ameliorating Drosophila research efforts compared to the conventional manual counting.

The new DIAMonDS reported by RIKEN researchers can be applied to accurately determine developmental transition in other small animals, and its applicability can be applied extensively in ongoing and future agricultural, medical and biological research.

Reference

Ki-Hyeon Seong, Taishi Matsumura, Yuko Shimada-Niwa, Ryusuke Niwa, Siu Kang. The Drosophila Individual Activity Monitoring and Detection System (DIAMonDS). eLife 2020;9:e58630.

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