Lavender (chicken plumage)

Lavender or self-blue refers to a plumage color pattern in the chicken (Gallus gallus domesticus) characterized by a uniform, pale bluish grey color across all feathers. The distinctive color is caused by the action of an autosomal recessive gene, commonly designated as "lav", which reduces the expression of eumelanin and phaeomelanin so that black areas of the plumage appear pale grey instead, and red areas appear a pale buff.[1]

Orpington hen exhibiting typical self-blue plumage due to lavender (lav) gene on black background.

Description

The "lavender" gene (lav) in the chicken causes the dilution of both black (eumelanin) and red/brown (phaeomelanin) pigments, so according to color background, dilution due to "lavender" gives a sort of plumage color patterns: On an extended black background, this condition causes the entire surface of the body an even shade of light slaty blue, which is the typical phenotype known as '"self-blue"'.

Pekin Bantam hen exhibiting the effect of lavender on a red plumage background

On a red/brown color plumage background, lavender gene degrades color to beige, like in some Pekin Bantams as in the picture set aside. On the color background of the Belgian Bearded d'Uccle Bantams, frequently referred to as the "Mille Fleur" in the United States,[2] lavender causes the pattern known as "porcelain". The resulting "porcelain" pattern is beige with each feather tipped with a V-shaped of slaty blue near the end of the feather and the feather tipped with a V-shaped white spangle.[3]

Light and electron microscope studies have revealed that, although lavender melanocytes possess relatively normal dendrite morphology, there is defective peripheral accumulation of melanosomes to the dendrites.[4] This results in the patchy transfer of melanosomes into the keratinocytes of the growing feather. The dilution effect is essentially the result of a mixture of pigmented and unpigmented regions within the feather barbs.

History

The lavender gene was first discovered in the Porcelain variety of Belgian Bearded d'Uccle bantams in 1972,[5] and verified in 1980.[1] Porcelain colored d'Uccle bantams were around as early as 1909, [6][7] though the Porcelain variety was not recognized by the American Poultry Association until 1964.[8] Whether from the Porcelain d'Uccle or other, unknown sources, the lavender gene has been introduced to a number of new chicken breeds over the years, including the Polish and the Silkie.

Genetic studies

"Lavender" is an autosomal recessive mutation of the chicken affecting the neural crest derived melanocytes. It causes the dilution of both eumelanin and phaeomelanin to a light grey or buff, respectively. It has been assigned the symbol lav.[5][9]

The ultimate goal of the modern genetic studies is to find out the underlying genes involved in these traits. Lavender in chickens has been found to be a mutation caused by a single base-pair change in exon 1 of MLPH (melanophilin) gene.[10]

In genetic linkage studies, Lav locus has been assigned to a linkage group known as Cp-R-U group (Creeper-Rose comb-Uropygial) . Although Lavender locus is linked to the R (rose comb) locus by 32.5%, its position has not yet mapped.,[11]

Homologous mutations in other species

Until now, all the reported causal mutations in MLPH (melanophilin) of humans, mice and other species have been single-base substitutions or small deletions, the effects of which were limited to the dilution of hair[12][13] or feather colour.[10] The MLPH-associated dilution of coat or plumage pigmentation should then result in the defective transport of melanosomes. This produces a diluted, leaden or lavender blue-grey colour and has been reported in several mammals: humans (Griscelli syndrome type 3),[12] mice,[14] cats,[15] dogs[16] and minks[17]

In Japanese quail

The lavender phenotype in Japanese quail (Coturnix coturnix japonica) is a dilution of both eumelanin and phaeomelanin in feathers that produces a blue-grey colour on a wild-type feather pattern background. Studies of intergeneric hybridization proved that the lavender mutation in quail is homologous to the same phenotype in chicken[18]

In this species, the lavender phenotype is associated with a non-lethal complex mutation involving three consecutive overlapping chromosomal changes (two inversions and one deletion) that have consequences on the genomic organization of four genes (MLPH and the neighbouring PRLH, RAB17 and LRRFIP1). The deletion of PRLH has no effect on the level of circulating prolactin. Lavender birds have lighter body weight, lower body temperature and increased feed consumption and residual feed intake than wild-type plumage quail, indicating that this complex mutation is affecting the metabolism and the regulation of homeothermy.[19]

In other bird species

In other bird species, similar feather colour dilutions have been described, including the autosomal recessive slate turkey (Meleagris gallopavo),[9][20] milky pigeon (Columba livia),[21] and the lavender muscovy duck (Cairina moschata).[22] It is as yet unknown which genes are responsible for these dilution mutations in these bird species.

Chicken breeds with "lavender" varieties

See also

References
  1. Crawford, Roy Poultry Breeding and Genetics, Elsevier, 1990
  2. The British Belgian Bantam Club Archived 2013-06-28 at the Wayback Machine
  3. http://www.feathersite.com/Poultry/CGK/Millies/BRKMilleFleur.html BRK Mille Fleur in Feathersite.com
  4. Mayerson PL, Brumbaugh JA: Lavender, a chick melanocyte mutant with defective melanosome translocation: a possible role for 10 nm filaments and microfilaments but not microtubules. J Cell Sci 1981, 51:25-51.
  5. Brumbaugh JA, Chatterjee G, Hollander WF: Adendritic melanocytes: a mutation in linkage group II of the fowl. J Hered 1972, 63:19-25.
  6. La Basse-Coeur du Nord archives 1882-1940]
  7. Articles traitent des races de poules belges, Nov 2008.
  8. American Belgian d'Uccle Bantam Club: Brief History: Belgian d'Uccle and Booted Bantam Archived 2013-07-29 at the Wayback Machine
  9. Somes, R. G. 1981 International Registry of Poultry Genetic Stocks. A Directory of Specialized Lines and Strains, Mutations, Breeds and Varieties of Chickens, Japanese Quail and Turkeys. Storrs Agricultural Experiment Station, The University of Connecticut, Storrs, Bulletin #460.
  10. Vaez, M., Follett, S.A., Bed’hom, B., Gourichon, D., Tixier-Boichard, M., Burke, T. 2008 A single point mutation within the melanophilin gene causes the lavender plumage colour dilution phenotype in the chicken. BMC Genet. 9:7.
  11. R. J. Etches and R. O. Hawes 1973 A summary of linkage relationships and a revised linkage map of the chicken. Canadian J. Genet. Cytol. 15:553-570.
  12. Ménasché, G., Ho, C.H., Sanal, O., Feldmann, J., Tezcan, I., Ersoy, F., Houdusse, A., Fischer, A., de Saint Basile, G. 2003 Griscelli syndrome restricted to hypopigmentation results from a melanophilin defect (GS3) or a MYO5A F-exon deletion (GS1). J. Clin. Invest. 112:450-456.
  13. Al-Idrissi, E., ElGhazali, G., AlZahrani, M., Ménasché, G., Schmid, J.P., de Saint Basile, G. 2010 Premature birth, respiratory distress, intracerebral hemorrhage, and silvery-gray hair: differential diagnosis of the 3 types of Griscelli syndrome. J. Pediatr. Hematol. Oncol. 23:365-374.
  14. Matesic, L.E., Yip, R., Reuss, A.E., Swing, D.A., O’Sullivan, T.N., Fletcher, C.F., Copeland, N.G., Jenkins, N.A. 2001 Mutations in Mlph, encoding a member of the Rab effector family, cause the melanosome transport defects observed in leaden mice. Proc. Natl. Acad. Sci. USA, 98:10238-10243.
  15. Ishida, Y., David, V.A., Eizirik, E., Schäffer, A.A., Neelam, B.A., Roelke, M.E., Hannah, S.S., O’Brien, S.J., Menotti-Raymond, M. 2006 A homozygous single-base deletion in MLPH causes the dilute coat colour phenotype in the domestic cat. Genomics 88:698-705.
  16. Welle, M., Philipp, U., Rüfenacht, S., Roosje, P., Scharfenstein, M., Schütz, E., Brenig, B., Linek, M., Mecklenburg, L., Grest, P., Drögemüller, M., Haase, B., Leeb, T., Drögemüller, C. 2009 MLPH genotype-melanin phenotype correlation in dilute dogs. J. Hered. 100:75-79
  17. Anistoroaei, R., Christensen, K. 2007 Mapping of the silver gene in mink and its association with the dilution gene in dog. Cytogenet. Genome Res. 116:316-318.
  18. F. Minvielle, D. Gourichon and J. L. Monvoisin. 2002 Testing homology of loci for two plumage colors, "lavender" and "recessive white", with chicken and Japanese quail hybrids. Journal of Heredity Vol. 93, Issue 1 Pp. 73-76.
  19. Bertrand Bed’hom, Mohsen Vaez, Jean-Luc Coville, David Gourichon, Olivier Chastel, Sarah Follett, Terry Burke and Francis Minvielle 2012 The lavender plumage colour in Japanese quail is associated with a complex mutation in the region of MLPH that is related to differences in growth, feed consumption and body temperature. BMC Genomics 13:442
  20. Jaap, R.G., Milby, T.T. Comparative genetics of blue plumage in poultry. Poult Sci 1944, 23:3-8.
  21. Levi, W.M. The pigeon. Sumter, SC: Levi Publishing; 1957.
  22. Hollander, W.F., Walther, P.L. 1962 Recessive "lavender" in the Muscovy duck. J. Hered., 53:81-3.
  23. "The Lavender Gene". 4 December 2014.
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