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ARHGAP36 and Cat Coat Color

1:16:00 recording · AUTO · 2 speakers

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Brief overview

A five-kilobase deletion near ARHGAP36 on the X chromosome is what makes cats orange.

  1. Orange comes from one 5 kilobase deletionThe deletion sits near ARHGAP36 on the X chromosome and raises the gene's expression 13-fold in skin.
  2. Two labs landed the answer at onceBarsh's group and Sasaki's group in Japan coordinated their preprints so neither was scooped.
  3. Charismatic traits open harder biologyCoat colour is easy to measure, so it becomes a foothold into signalling that also runs in brain and gland tissue.
Executive Summary AI
  • Nels Elde brings Vincent Racaniello a bioRxiv preprint from Greg Barsh's lab on the genetic basis of sex-linked orange coat colour in the domestic cat, the holiday edition of Twevo 109.9:07
  • Earlier breeding crosses had placed the orange trait in a 10 megabase stretch of the X chromosome, and this team used sequenced cat genomes to cut that to one megabase, then to 50 candidate mutations and finally to three, of which the strongest was a 5 kilobase deletion near a gene called ARHGAP36.24:40
  • About 150 further orange cat genomes all carried that five kilobase deletion and roughly 50 non-orange cats all lacked it, while the other two candidate regions did not track coat colour.31:39
  • In neonatal skin the gene is expressed 13 times higher in orange cats than in non-orange ones, six neighbouring genes are unchanged, and MC1R and its pathway are turned down, which shifts pigment from dark eumelanin to orange pheomelanin; a Japanese group under Hiroyuki Sasaki at Kyushu University reached the same conclusion and posted at the same time.33:07
  • For his pick Nels plays a minute of a Google Notebook LM audio overview generated from this same preprint, and the two hosts agree it is a useful way into the literature but no substitute for human hosts, their foibles and their stories.1:00:20
Key Quote
“Sex-linked orange, SLO, is the genetic region that's been identified.”
— Nels20:28
Key Quote
“We might be out of a job here shortly, Vincent.”
— Nels1:00:46
Key Quote
“I'm not ready to hang up the shoes yet for Twevo.”
— Nels1:07:05