Establishment of the mayfly Cloeon dipterum as a new model system to investigate insect evolution

Abstract

The great capability of insects to adapt to new environments promoted their extraordinary diversification, resulting in the group of Metazoa with the largest number of species distributed worldwide. To understand this enormous diversity, it is essential to investigate lineages that would allow the reconstruction of the early events in the evolution of insects. However, research on insect ecology, physiology, development and evolution has mostly focused on few well-established model species. The key phylogenetic position of mayflies within Paleoptera, as the sister group of the rest of winged insects and life history traits of mayflies make them an essential order to understand insect evolution. Here, we describe the established of a continuous culture system of the mayfly Cloeon dipterum and a series of experimental protocols and -omics resources that allow the study of its development and its great regenerative capability. Thus, the establishment of Cloeon as an experimental platform paves the way to understand genomic and morphogenetic events that occurred at the origin of winged insects.

Genomic adaptations to aquatic and aerial life in mayflies and the origin of insect wings

“…Genome sequencing and assembly. Genomic DNA was extracted from C. dipterum adult males from an inbred line kept in the laboratory for seven generations 10 . Illumina and Nanopore technologies were used to sequence the genome (Supplementary Data 2-4 and Supplementary Note 1).…”

“…We found that more than half of CS genes, and among these, nearly 80% of OBPs (147 out of 276 CS genes and 121 out of 152 OBPs included in the soft-clustering analysis) were mostly assigned to just four clusters (18, 12, 9 and 10), all of them related to nymphal or pre-nymphal stages. Cluster 10 contained genes that had a peak of expression at 14 dpf stage, just prior to the hatching of the first swimming nymph 10 , and genes in clusters 9, 12 and 18 were most highly expressed during nymphal stages (Fig. 3b).…”

“…The recent establishment of a continuous culture system of the mayfly Cloeon dipterum, a cosmopolitan Baetidae species with a life cycle of just 6 weeks, makes it now possible to access all embryonic and post-embryonic stages. This overcomes past difficulties to study paleopterans which are generally not very amenable to rear in the laboratory; with mayflies having the additional challenge of being extremely short-lived as adults 10 .…”

Mayflies in Ecotoxicity Testing: Methodological Needs and Knowledge Gaps

“…Therefore, care should be taken if the results from these tests are to be used for regulatory purposes. However, a recently published protocol for culturing C. dipterum (Almudi et al 2019) should be evaluated with respect to its potential use in aquatic toxicity testing.…”

The mayfly subimago explained. The regulation of metamorphosis in Ephemeroptera

“…The copyright holder for this preprint this version posted March 17, 2021. ; https://doi.org/10.1101/2021.03.17.435759 doi: bioRxiv preprint subimaginal stage that lasts about 1 day, and the adult that can live 10-20 days, which is exceptionally long for mayflies (14).…”