1 / 24

Drosophila homeotic mutants

Drosophila homeotic mutants. Homeotic (Hox) gene complexes in Drosophila. lab. pb. Dfd. Scr. Antp. Ubx. abdA. AbdB. labial. Deformed. Antennapedia. abdominal-A. proboscipedia. Sex combs reduced. Ultrabithorax. Abdominal-B. Antennapedia Complex (ANT-C). Bithorax Complex (BX-C).

arthur-pierce
Download Presentation

Drosophila homeotic mutants

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Drosophila homeotic mutants

  2. Homeotic (Hox) gene complexes in Drosophila lab pb Dfd Scr Antp Ubx abdA AbdB labial Deformed Antennapedia abdominal-A proboscipedia Sex combs reduced Ultrabithorax Abdominal-B Antennapedia Complex (ANT-C) Bithorax Complex (BX-C)

  3. labial Antennapedia Ultrabithorax proboscipedia Deformed abdominal A Sex combs reduced Abdominal B Expression patterns of homeotic genes in embryogenesis pb Ubx AbdB Dfd Scr Antp abdA lab

  4. Two types of homeotic mutants in Drosophila dominant mutations gain-of-function Transformations “anterior to posterior“ recessive mutations loss-of-function Transformations “posterior to anterior“

  5. Antennapedia - a homeotic mutant antennenal segments Arista coxa claw troch- anter tarsal segments tibia femur Antp / + antenna and leg are serially homologous limbs antenna transformed into leg

  6. proboscipedia - transformation of mouthparts into legs mx mx* lb lb*

  7. Bithorax Complex (BX-C) regulatory mutations Coding-region mutations Complex homeotic gene regulation

  8. Ubx is expressed in T3 and A1

  9. Ultrabithorax binds DNA and regulates genes required for T3 and A1 T3,A1 Ultrabithorax expression Ubx protein OFF ON T2 specific gene OFF T3 specific gene ON A5 specific gene A1 specific gene

  10. All abdominal segments take on a T2 identity if the bithorax complex is deleted ubxabdA abdB triple mutant Wild type T2 T3 A1 T2 T2 T2 A8 T2

  11. Antennapedia expression expands in flies mutant for the Bithorax complex genes ANT-C BX-C

  12. Ultrabithorax, AbdA, and AbdB normally repress expression of the thorax-specific “leg gene” Distalless in the abdominal segments wild-type ubxabdA abdB triple mutant abdomen T1 T2 T3

  13. Persistence of homeotic gene expression through development Adult Imaginal discs larva embryo

  14. Maintenance of homeotic gene expression trithorax group (Trx-G) maintenance of transcriptionally activestate maintenance of transcriptionally inactive state Polycomb group (Pc-G) Trx-G Pc-G transcriptionally open chromatin transcriptionally closed chromatin pb Dfd Scr Antp extradenticle Exd Dfd realisator gene

  15. Lewis hypothesized that the duplication and diversification of homeotic master regulators underlies the evolution of an increasingly complex body plan

  16. Distal-less gene required for limb development Drosophila Precis (butterfly)

  17. The human body is also built up from reiterated units (segments) with different identities along the A/P axis

  18. Hox gene expression in mouse embryos

  19. Mouse HOX gene expression patterns

  20. Mouse hoxa3 and hoxd3 mutants from Nature 370: 304-307 (1994)

  21. Wild-type mouse forelimb hoxa-11 hoxd-11 Human hoxD13 mutation

More Related