{"id":{"repo_id":"oxford-brookes","oai_identifier":"tle:96ccf884-83fd-4575-963b-833a62c8c7d2:d6bd9758-527a-46cd-bfe2-c433766e8fca:1"},"canonical_url":"https://search.dev.ndltd.org/etd/oxford-brookes/tle:96ccf884-83fd-4575-963b-833a62c8c7d2:d6bd9758-527a-46cd-bfe2-c433766e8fca:1","repository":{"repo_id":"oxford-brookes","name":"Oxford Brookes University","base_url":"https://radar.brookes.ac.uk/radar/oai"},"display":{"title":"Head and protocerebral patterning in the spider Parasteatoda tepidariorum","abstract":"Chelicerates (including spiders, scorpions, horseshoe crabs, mites and ticks) diverged from other mandibulate arthropods (insects, crustaceans, centipedes and millipedes) around 500 million years ago, making them good models to study whether traits and mechanisms of development are ancestral or derived with respect to the arthropod common ancestor. An arachnopulmonate-arachnid, the spider Parasteatoda tepidarium has emerged as one of the main chelicerate model species for evolutionary and developmental biology. The arthropod protocerebrum is derived from the neurogenetic ectoderm of the pre-antennal/cheliceral region. It gives rise to centres or neuropils, which in insects are essential for spatial orientation and object recognition (central complex) and olfactory learning and memory (mushroom bodies/MB). However, it is not clear whether the chelicerate arcuate body and spider MB are homologous to insect central complex and MB, respectively. The overall aim of this thesis is the homology of arthropod brain regions through a comparison of gene expression patterns during spider embryogenesis. To understand the regulation of the development of the spider pre-cheliceral region, cheliceral and pedipalp segments of the spider embryo, I first analysed marker genes in five putative anterior cell clusters from scRNA-seq analysis at three embryonic stages of P. tepidariorum (Leite et al., 2024). I found two clusters corresponded to the pedipalpal segment, two clusters corresponded to the pre-cheliceral region: a six3- expressing anterior and otd2-expressing posterior cluster and one to the hh1-expressing pre- cheliceral/cheliceral boundary. This work provided new insights into pre-cheliceral patterning and supports conclusions made by Posnien et al. (2023), such as the location of the vertebrate mid- and hindbrain boundary homolog. I then characterised the development of neuroendocrine cell populations in the six3-expression region by analysing the expression of neuroendocrine marker genes from insects and centipedes during spider embryogenesis. I found that spiders have cell populations corresponding to the insect neuroendocrine centres the pars intercerebralis and pars lateralis, the first to be identified in a chelicerate and placing their origin to the arthropod common ancestor. This work further supports the homology of spiders and insects at the level of anterior neuroectoderm patterning and homology of their neuropils. Finally, I analysed the retention of ohnologs in key developmental genes (Hox, Wnt, Frizzled, and head patterning genes) following whole-genome duplication in arachnopulmonates. The improved taxonomic sampling provided further evidence for the ancestral arachnopulmonate whole genome duplication and allowed me to identify likely patterns of ohnolog retention and loss. Furthermore, I identified the first reported duplicates of Wnt1/wg in any animal and the first Wnt10 in any arachnid, and the first vax in a spider.","abstract_html":"Chelicerates (including spiders, scorpions, horseshoe crabs, mites and ticks) diverged from other mandibulate arthropods (insects, crustaceans, centipedes and millipedes) around 500 million years ago, making them good models to study whether traits and mechanisms of development are ancestral or derived with respect to the arthropod common ancestor. An arachnopulmonate-arachnid, the spider Parasteatoda tepidarium has emerged as one of the main chelicerate model species for evolutionary and developmental biology. The arthropod protocerebrum is derived from the neurogenetic ectoderm of the pre-antennal/cheliceral region. It gives rise to centres or neuropils, which in insects are essential for spatial orientation and object recognition (central complex) and olfactory learning and memory (mushroom bodies/MB). However, it is not clear whether the chelicerate arcuate body and spider MB are homologous to insect central complex and MB, respectively. The overall aim of this thesis is the homology of arthropod brain regions through a comparison of gene expression patterns during spider embryogenesis. To understand the regulation of the development of the spider pre-cheliceral region, cheliceral and pedipalp segments of the spider embryo, I first analysed marker genes in five putative anterior cell clusters from scRNA-seq analysis at three embryonic stages of P. tepidariorum (Leite et al., 2024). I found two clusters corresponded to the pedipalpal segment, two clusters corresponded to the pre-cheliceral region: a six3- expressing anterior and otd2-expressing posterior cluster and one to the hh1-expressing pre- cheliceral/cheliceral boundary. This work provided new insights into pre-cheliceral patterning and supports conclusions made by Posnien et al. (2023), such as the location of the vertebrate mid- and hindbrain boundary homolog. I then characterised the development of neuroendocrine cell populations in the six3-expression region by analysing the expression of neuroendocrine marker genes from insects and centipedes during spider embryogenesis. I found that spiders have cell populations corresponding to the insect neuroendocrine centres the pars intercerebralis and pars lateralis, the first to be identified in a chelicerate and placing their origin to the arthropod common ancestor. This work further supports the homology of spiders and insects at the level of anterior neuroectoderm patterning and homology of their neuropils. Finally, I analysed the retention of ohnologs in key developmental genes (Hox, Wnt, Frizzled, and head patterning genes) following whole-genome duplication in arachnopulmonates. The improved taxonomic sampling provided further evidence for the ancestral arachnopulmonate whole genome duplication and allowed me to identify likely patterns of ohnolog retention and loss. Furthermore, I identified the first reported duplicates of Wnt1/wg in any animal and the first Wnt10 in any arachnid, and the first vax in a spider.","abstract_has_math":false,"creators":["Harper, Amber"],"institution":"Oxford Brookes University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["McGregor, Alistair"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T03:42:31Z","subjects":[],"languages":["en"],"rights":["All rights reserved"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://doi.org/10.24384/74a4-kh25","outbound_label":"DOI","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["McGregor, Alistair","Harper, Amber"]},{"key":"dc:creator","label":"Author","values":["Harper, Amber"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Oxford Brookes University"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["All rights reserved"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://doi.org/10.24384/74a4-kh25","https://radar.brookes.ac.uk/radar/file/96ccf884-83fd-4575-963b-833a62c8c7d2/1/AHarper_19012072_corrected.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Chelicerates (including spiders, scorpions, horseshoe crabs, mites and ticks) diverged from other mandibulate arthropods (insects, crustaceans, centipedes and millipedes) around 500 million years ago, making them good models to study whether traits and mechanisms of development are ancestral or derived with respect to the arthropod common ancestor. An arachnopulmonate-arachnid, the spider Parasteatoda tepidarium has emerged as one of the main chelicerate model species for evolutionary and developmental biology. The arthropod protocerebrum is derived from the neurogenetic ectoderm of the pre-antennal/cheliceral region. It gives rise to centres or neuropils, which in insects are essential for spatial orientation and object recognition (central complex) and olfactory learning and memory (mushroom bodies/MB). However, it is not clear whether the chelicerate arcuate body and spider MB are homologous to insect central complex and MB, respectively. The overall aim of this thesis is the homology of arthropod brain regions through a comparison of gene expression patterns during spider embryogenesis. To understand the regulation of the development of the spider pre-cheliceral region, cheliceral and pedipalp segments of the spider embryo, I first analysed marker genes in five putative anterior cell clusters from scRNA-seq analysis at three embryonic stages of P. tepidariorum (Leite et al., 2024). I found two clusters corresponded to the pedipalpal segment, two clusters corresponded to the pre-cheliceral region: a six3- expressing anterior and otd2-expressing posterior cluster and one to the hh1-expressing pre- cheliceral/cheliceral boundary. This work provided new insights into pre-cheliceral patterning and supports conclusions made by Posnien et al. (2023), such as the location of the vertebrate mid- and hindbrain boundary homolog. I then characterised the development of neuroendocrine cell populations in the six3-expression region by analysing the expression of neuroendocrine marker genes from insects and centipedes during spider embryogenesis. I found that spiders have cell populations corresponding to the insect neuroendocrine centres the pars intercerebralis and pars lateralis, the first to be identified in a chelicerate and placing their origin to the arthropod common ancestor. This work further supports the homology of spiders and insects at the level of anterior neuroectoderm patterning and homology of their neuropils. Finally, I analysed the retention of ohnologs in key developmental genes (Hox, Wnt, Frizzled, and head patterning genes) following whole-genome duplication in arachnopulmonates. The improved taxonomic sampling provided further evidence for the ancestral arachnopulmonate whole genome duplication and allowed me to identify likely patterns of ohnolog retention and loss. Furthermore, I identified the first reported duplicates of Wnt1/wg in any animal and the first Wnt10 in any arachnid, and the first vax in a spider."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Head and protocerebral patterning in the spider Parasteatoda tepidariorum"]}]}],"canonical_facts":{"dc:contributor":["McGregor, Alistair","Harper, Amber"],"dc:creator":["Harper, Amber"],"dc:description":["Chelicerates (including spiders, scorpions, horseshoe crabs, mites and ticks) diverged from other mandibulate arthropods (insects, crustaceans, centipedes and millipedes) around 500 million years ago, making them good models to study whether traits and mechanisms of development are ancestral or derived with respect to the arthropod common ancestor. An arachnopulmonate-arachnid, the spider Parasteatoda tepidarium has emerged as one of the main chelicerate model species for evolutionary and developmental biology. The arthropod protocerebrum is derived from the neurogenetic ectoderm of the pre-antennal/cheliceral region. It gives rise to centres or neuropils, which in insects are essential for spatial orientation and object recognition (central complex) and olfactory learning and memory (mushroom bodies/MB). However, it is not clear whether the chelicerate arcuate body and spider MB are homologous to insect central complex and MB, respectively. The overall aim of this thesis is the homology of arthropod brain regions through a comparison of gene expression patterns during spider embryogenesis. To understand the regulation of the development of the spider pre-cheliceral region, cheliceral and pedipalp segments of the spider embryo, I first analysed marker genes in five putative anterior cell clusters from scRNA-seq analysis at three embryonic stages of P. tepidariorum (Leite et al., 2024). I found two clusters corresponded to the pedipalpal segment, two clusters corresponded to the pre-cheliceral region: a six3- expressing anterior and otd2-expressing posterior cluster and one to the hh1-expressing pre- cheliceral/cheliceral boundary. This work provided new insights into pre-cheliceral patterning and supports conclusions made by Posnien et al. (2023), such as the location of the vertebrate mid- and hindbrain boundary homolog. I then characterised the development of neuroendocrine cell populations in the six3-expression region by analysing the expression of neuroendocrine marker genes from insects and centipedes during spider embryogenesis. I found that spiders have cell populations corresponding to the insect neuroendocrine centres the pars intercerebralis and pars lateralis, the first to be identified in a chelicerate and placing their origin to the arthropod common ancestor. This work further supports the homology of spiders and insects at the level of anterior neuroectoderm patterning and homology of their neuropils. Finally, I analysed the retention of ohnologs in key developmental genes (Hox, Wnt, Frizzled, and head patterning genes) following whole-genome duplication in arachnopulmonates. The improved taxonomic sampling provided further evidence for the ancestral arachnopulmonate whole genome duplication and allowed me to identify likely patterns of ohnolog retention and loss. Furthermore, I identified the first reported duplicates of Wnt1/wg in any animal and the first Wnt10 in any arachnid, and the first vax in a spider."],"dc:format":["application/pdf"],"dc:identifier":["https://doi.org/10.24384/74a4-kh25","https://radar.brookes.ac.uk/radar/file/96ccf884-83fd-4575-963b-833a62c8c7d2/1/AHarper_19012072_corrected.pdf"],"dc:language":["en"],"dc:publisher":["Oxford Brookes University"],"dc:rights":["All rights reserved"],"dc:title":["Head and protocerebral patterning in the spider Parasteatoda tepidariorum"],"dc:type":["thesis"]},"updated_at":"2026-07-24T03:42:31Z"}