Tribolium ovariole showing oocytes (unlaid eggs) at different stages of development; taken from a transgenic beetle in which nuclear localized green-fluorescent protein (nGFP) is ubiquitously expressed (green). Acetylated tubulin is stained red. Image by Andrew Peel.
Tribolium terminal oocyte, now filled with yoke, and almost ready to be laid – taken from a transgenic beetle in which nuclear localized green-fluorescent protein (nGFP) is ubiquitously expressed (green). Acetylated tubulin is stained red. Image by Andrew Peel.
View down on the anterior pole of a recently laid (1-2 hours old) Tribolium egg showing anteriorly localized mRNA of the gene Tc-pangolin (red) associated with a cortical microtubule network (green) (see Peel & Averof, 2010). Image by Andrew Peel.
Mitotic events in a Tribolium embryo
A mitotic wave sweeping across a Tribolium blastoderm embryo (from bottom left to top right). Note the leakage of nGFP (green) when the nuclear envelope (red) breaks down prior to mitosis. Image by Andrew Peel.
Early Tribolium germband embryo
An early germband embryo, with nuclear membranes stained red, at the beginning of axis elongation and the formation of abdominal segments. The developing head lobes are at the top. Image by Andrew Peel.
Early Tribolium germband embryo
Early Tribolium germband embryo showing expression of two genes (Tc-even-skipped and Tc-odd-skipped) involved in segment formation that are expressed out-of-phase with one another (see Sarrazin et al., 2012). Image by Andrew Peel.
Elongating Tribolium embryo
An elongating Tribolium embryo showing expression of the segmentation gene Tc-engrailed (blue) and the Hox gene Tc-Deformed (red) (see Peel et al., 2013). Image by Andrew Peel.
Abdominal region - Drosophila embryo
Abdominal region of a Drosophila embryo showing expression of the engrailed-family genes engrailed (red) and invected (green) (see Peel et al., 2006). Nuclei are stained blue. Image by Andrew Peel.
An elongating Tribolium embryo stained for expression of the gene Tc-odd-skipped (see Sarrazin et al., 2012). Image by Andrew Peel.
Drosophila blastoderm embryo
Drosophila blastoderm embryo showing expression of the segmentation gene fushi-tarazu (yellow). Nuclei are stained grey. Image by Andrew Peel.
Multiplex in situ hybridisation on an extended germband Drosophila embryo showing expression of five developmental genes: antennapedia (yellow), sex combs reduced (red), Deformed (blue), labial (green) and distal-less (purple). Image by Andrew Peel.
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Current Group Members
Andrew Peel - Group leader
Bradleigh Cocker (PhD student; Oct 2018 - )
Jacob Leese (BBSRC PhD student; Oct 2018 - )
Past Group Members
Rahul Sharma (Research Fellow - BBSRC)
Matthew Dooley (BBSRC/Fera PhD student; Oct 2014 - 2019)
Pete Harrison (Oct 2014 -2016)
More about Peel Lab
Our lab is interested in how animal evolution occurs at different levels of biological complexity; i.e. genetic, cellular, organismal and ecological. Our research efforts to date have focused on understanding how diversity in animal body plans evolved.
Our work compares the genetic and cellular mechanisms controlling
embryogenesis in different animal species in order to identify the molecular changes that underpinned divergence in animal body plans during evolution.
The Peel laboratory is part of the following University of Leeds, School of Biology's Research groups:
- Ecology and Evolution
- Heredity, Development and Disease
To learn more about the research groups, current research and modules, as well as, the academic roles of Andrew Peel follow the link below.
The red flour beetle Tribolium castaneum
Our research currently focuses on a laboratory model insect species, the red flour beetle Tribolium castaneum. This is a holometabolous insect species, meaning that it exhibits 'complete metamorphosis', passing from larva to adult via a pupal stage. We study Tribolium because it is becoming increasing amenable to genetic manipulation in the laboratory and has retained a number of interesting ancestral developmental traits, such as the sequential formation of body segments during embryogenesis.
Peel, AD. (2009). The evolution of developmental gene networks: lessons from comparative studies on holometabolous insects. Animal Evolution: Genomes, Fossils, and Trees. M. J. Telford and D. T. J. Littlewood, Oxford University Press. pp.171 -182.
The evolution of segmentation mechanisms in holometabolous insects
One of the aims of our work is to provide important insights into how developmental gene networks evolve. This can be achieved by gaining a deep understanding of the developmental genetic mechanisms operating in Tribolium, and identifying how these are similar or different to the development genetic mechanisms operating in other holometabolous insect species; e.g. the parasitic wasp Nasonia vitripennis, the honeybee Apis mellifera, the moths Bombyx mori and Manduca sexta, and the fruit fly Drosophila melanogaster (see Peel, 2008. Philos. Trans. R. Soc. Lond. B. Biol. Sci.). We are interested in using comparative developmental biology to understand how the gene networks controlling body segment formation have evolved (see Peel, Chipman & Akam, 2005. Nat. Rev. Genet.).
Ancestrally, insects developed their trunk segments sequentially, in an anterior-to-posterior progression. This developmental trait is found in more primitive, non-holometabolous, insect species, such as grasshoppers and true bugs, as well as non-insect arthropods such as centipedes and spiders. The beetle Tribolium is an example of a holometabolous insect species that has also retained this ancestral trait during evolution. However, many other holometaoblous insects, including Nasonia, Apis and Drosophila, have evolved a faster mode of development in which all body segments form more-or-less simultaneously.
By studying the genetic and cellular mechanisms underlying Tribolium body segment specification we can explore how this evolutionary transition from sequential to simultaneous segmentation might have occurred.
The origin and evolution of segmentation mechanisms in animals
We also make comparisons between much more distantly related animals. Andrew's recent work contributed to demonstrating that the genetic developmental mechanism controlling the formation of body segments in Tribolium shows striking similarities to the developmental mechanism that gives rise to repeated internal body structures in humans, such as our vertebrate/ribs and their associated muscle (see Sarrazin*, Peel* & Averof, 2012. Science).
Segmented structures in arthropods and vertebrates both form under the control of a 'segmentation clock' gene network. We are currently investigating whether the arthropod and vertebrate segmentation clocks are sufficiently similar at the genetic level to suggest that they were both inherited from the common ancestor of arthropods and vertebrates. This ancestral animal lived over 550 million years ago. The alternative possibility is that arthropod and vertebrate segmentation clocks represent an interesting case of parallel evolution, in which similar gene networks have evolved, or been recruited, independently, to pattern reiterated morphological structures.
Either way, our work promises to offer important insights into some of the earliest events in the evolution of animal developmental mechanisms.
Clark, E., Peel, AD., & Akam, M. (2019). Arthropod segmentation. Development. 146(18), dev170480. DOI:10.1242/dev.170480
Peel AD*; Schanda J*; Grossmann D*; Ruge F; Oberhofer G; Gilles AF; Schinko JB; Klingler M; Bucher G (2013). Tc-knirps plays different roles in the specification of antennal and mandibular parasegment boundaries and is regulated by a pair-rule gene in the beetle Tribolium castaneum. BMC Dev. Biol. Vol. 13:25
Sarrazin AF*; Peel AD*; Averof M (2012). A segmentation clock with two-segment periodicity in insects. Science Vol. 336, 338-341
Peel AD; Averof M (2010). Early asymmetries in maternal transcript distribution associated with a cortical microtubule network and a polar body in the beetle Tribolium castaneum. Dev. Dyn. Vol. 239, 2875-2887
Lynch JA; Peel AD; Drechsler A; Averof M; Roth S (2010). EGF signaling and the origin of axial polarity among the insects. Curr. Biol. Vol. 20, 1042-1047
Peel AD (2008). The evolution of developmental gene networks: lessons from comparative studies on holometabolous insects. Philos. Trans. R. Soc. Lond. B. Biol. Sci. Vol. 363, 1539-1547
Peel AD; Telford MJ; Akam M (2006). The evolution of hexapod engrailed-family genes: evidence for conservation and concerted evolution. Proceedings. Biological sciences / The Royal Society Vol. 273, 1733-1742
Peel AD; Chipman AD; Akam M (2005). Arthropod segmentation: beyond the Drosophila paradigm. Nat. Rev. Genet. Vol. 6, 905-916
Peel A; Akam M (2003). Evolution of segmentation: rolling back the clock. Curr. Biol. Vol. 13, R708-R710
Flour beetles are also a classical laboratory model system for studying intra- and interspecific ecological interactions, and among many significant beetle pests of stored food products. In collaboration with other members of the School of Biology we are currently developing a number of projects investigating the genetic factors that influence Tribolium behaviour and community ecology, with a view to improving beetle pest management and understanding the factors involved in the maintenance of species diversity.