56) Coat color inheritance in domestic animals: pigment synthesis, pigment types, albinism

Question 1

MSH

Answer 1

• Melanocyte-stimulating hormone
• Attaches to MSH-R-receptors on melanocytes

Question 2

MSH causes…

Answer 2

• Tyrosinase enzyme activity increase
• Pigment synthesis in melanosomes
  
  • Eumelanin
  • Pheomelanin

Question 3

MSH-receptor gene mutations of alleles occur at the…

Answer 3

MSHR locus (E locus)

Question 4

Give the alleles of basic coat colours

Answer 4

• E+
• EsuperD
• e

Question 5

E+ allele

Answer 5

• Normal, MSH dependent tyrosinase activity
• Different eu- and phaeomelanin production
• Creates agouti colour

Question 6

EsuperD

Answer 6

• Continuous tyrosinase activity
• MSH-binding not necessary
• Only eumelanin produced
• = non-agouti protein = black colour

Question 7

e

Answer 7

• Low tyrosinase activity
• Non-functional receptor
• Red coat colour
• Only pheomelanin produced

Question 8

List the pigment types

Answer 8

• A - Agouti
• B - Brown
• C - Albino, no colour
• E - Extension
• D - Grey
• Indowhite - Palamino
• R - Roan

Question 9

Albinism

Answer 9

• Gene effect causes tyrosinase activity inside melanocyte cells
• Disrupts melanocyte-production (Enzyme needed for first step)
• No pigments created