title: CRISPR/Cas9 Mutagenesis Reveals Versatile Roles of Hox Genes in Crustacean Limb Specification and Evolution.
abstract: Crustaceans possess a diverse array of specialized limbs. Although shifts in Hox gene expression domains have been postulated to play a role in generating this limb diversity, little functional data have been provided to understand the precise roles of Hox genes during crustacean development. We used a combination of CRISPR/Cas9-targeted mutagenesis and RNAi knockdown to decipher the function of the six Hox genes expressed in the developing mouth and trunk of the amphipod Parhyale hawaiensis. These experimentally manipulated animals display specific and striking homeotic transformations. We found that abdominal-A (abd-A) and Abdominal-B (Abd-B) are required for proper posterior patterning, with knockout of Abd-B resulting in an animal with thoracic type legs along what would have been an abdomen, and abd-A disruption generating a simplified body plan characterized by a loss of specialization in both abdominal and thoracic appendages. In the thorax, Ubx is necessary for gill development and for repression of gnathal fate, and Antp dictates claw morphology. In the mouth, Scr and Antp confer the part-gnathal, part-thoracic hybrid identity of the maxilliped, and Scr and Dfd prevent antennal identity in posterior head segments. Our results allow us to define the role Hox genes play in specifying each appendage type in Parhyale, including the modular nature by which some appendages are patterned by Hox gene inputs. In addition, we define how changes in Hox gene expression have generated morphological differences between crustacean species. Finally, we also highlight the utility of CRISPR/Cas9-based somatic mutagenesis in emerging model organisms.
authors.affiliation: Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Martin
authors.affiliation: Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Serano
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Jarvis
authors.affiliation: Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA.
authors.forename: Heather S
authors.initials: HS
authors.lastname: Bruce
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA.
authors.forename: Shagnik
authors.initials: S
authors.lastname: Ray
authors.affiliation: Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA.
authors.forename: Carryn A
authors.initials: CA
authors.lastname: Barker
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA.
authors.forename: Liam C
authors.initials: LC
authors.lastname: O'Connell
authors.affiliation: Department of Molecular Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200 USA; Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140 USA. Electronic address: nipam@uclink.berkeley.edu.
authors.forename: Nipam H
authors.initials: NH
authors.lastname: Patel
mesh_terms: D033304:Amphipoda / Q000196:embryology / Q000235:genetics*; D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics; D005075:Biological Evolution; D064130:CRISPR-Associated Proteins / Q000235:genetics*; D064113:CRISPR-Cas Systems; D002454:Cell Differentiation / Q000235:genetics; D003001:Cloning, Molecular; D064112:Clustered Regularly Interspaced Short Palindromic Repeats / Q000235:genetics; D003445:Crustacea / Q000196:embryology* / Q000235:genetics; D004625:Embryo, Nonmammalian; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017403:In Situ Hybridization; D008297:Male; D016296:Mutagenesis; D034622:RNA Interference
chemical_list: D060829:Arthropod Proteins; D064130:CRISPR-Associated Proteins