Anatomical constraints on venom and toxin evolution in giant centipedes.

Background

Venoms are biochemical arsenals that have evolved on numerous occasions throughout the animal kingdom. They consist mainly of proteins and peptides that have evolved from physiological “house-keeping” proteins to become potent toxins, and venomous animals have therefore attracted attention as sources of new molecular tools and lead molecules for development as therapeutics and agrochemicals. More recently, venoms have also emerged as models for studying evolution, with a particular focus on how proteins and peptides evolve new functions. Because toxins from animal venoms have to be injected by specialised venom-delivery structures in order to function (using e.g., barbs, teeth, stingers), there is a strong association between the molecular evolution of toxins and the morphological evolution of associated toxin-producing tissues and venom-delivering structures. Venoms and their associated structures are thus excellent subjects for studying how the interactions of how different traits affect their evolution.

The morphological complexity of the venom gland and toxin diversity present in the venom differ between centipedes. (A) Comparative morphology of the venom apparatuses of Thereuopoda longicornis (Top), Scolopendra morsitans (Middle), and Ethmostigmus rubripes (Bottom), showing three-dimensional

MRI reconstructions of forcipule (white), venom gland (red), and duct (dark red), as well as low-magnification overview of histological transverse sections of the same venom glands. (B) Molecular diversity of toxins detected by proteotranscriptomic analysis of centipede venoms shown as heatmaps organised according to independently recruited toxin families. Adapted from Undheim et al. (2015) and Jenner et al. (2019).

Masters project

This project seeks to better understand the factors that drive and constrain the abilities of traits to evolve by examining how the evolution of venom is affected by the anatomy of the venom-producing tissues. The project will focus on the venom and venom gland anatomy of giant centipedes in the family Scolopendridae. Centipedes are among the most ancient terrestrial venomous lineages, and members of the family Scolopendridae are infamous for using their venom to incapacitate an exceptional wide range of prey, including spiders, snakes, and even bats. Interestingly, the evolution of the rich toxin arsenal of giant centipedes appears to have been facilitated by anatomical features of their venom gland that increase the number of toxin-producing cells by up to three orders of magnitude compared to other centipedes. However, it remains unknown to what degree this morphological adaptation has shaped subsequent toxin evolution in giant centipedes since its initial emergence, and how toxin evolution is affected by other traits such as body size.

To test hypotheses on venom evolution and adaptation, the student will use a combination of transcriptome analyses, analyses of proteomic data, molecular phylogenetics, micro-computer tomography, microscopy, and phylogenetic comparative models. The student will be based mainly at CEES, IBV, but will also have opportunities to visit and spend time working in the labs of international project collaborators.

Main supervisor: Eivind A. B. Undheim

Co-supervisor: Kjetil L. Voje

Background references:

Jenner RA, von Reumont BM, Campbell LI, Undheim EAB (2019) Parallel evolution of complex venoms in centipedes revealed by comparative proteotranscriptomic analyses. Molecular Biology and Evolution — in press. (https://doi.org/10.1093/molbev/msz181)

Undheim EAB, Hamilton BR, Kurniawan N, Bowlay G, Cribb B, Merritt D, Fry BG, King GF, and Venter DJ (2015) Production and packaging of a biological arsenal: centipede venom evolution under morphological constraint. Proceedings of the National Academy of Sciences USA 112: 4026–4031. (https://doi.org/10.1073/pnas.1424068112)

Undheim EAB, Jones A, Holland JW, Clauser K, Pineda SS, King GF and Fry BG (2014) Clawing through evolution: toxin diversification and convergence in the ancient lineage Chilopoda (centipedes). Molecular Biology and Evolution 31, 2124–2148. (https://doi.org/10.1093/molbev/msu162)

Publisert 26. aug. 2019 07:47 - Sist endret 26. aug. 2019 07:47

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