TLDR The research identified two types of keratinocytes in chicken scales: one for hard scales and another for soft skin, with similarities to human skin differentiation.
This study explored the differentiation of keratinocytes in avian scutate scales by using single-cell transcriptomics on cells from the skin of 1-day old chicks. Two distinct populations of differentiated keratinocytes were identified: one characterized by mRNAs for cysteine-rich keratins and scale-type corneous beta-proteins (CBPs), which form hard scales, and another with mRNAs for cysteine-poor keratins and keratinocyte-type CBPs, associated with the formation of soft interscale epidermis. An antibody against keratin 9-like cysteine-rich 2 (KRT9LC2), enriched in the first population, was used for immunostaining, confirming its expression in the hard scales but not in the interscale epidermis. The study also found similarities in keratinocyte differentiation between chicken leg skin and human skin, including the upregulation of epidermal differentiation complex genes and genes involved in lipid metabolism and transport, suggesting evolutionary conservation in these processes.
36 citations,
November 2019 in “Molecular biology and evolution” Cysteine-rich keratins evolved independently in mammals, reptiles, and birds for hard skin structures like hair, claws, and feathers.
72 citations,
December 2018 in “Journal of Experimental Zoology Part B Molecular and Developmental Evolution” Corneous beta-proteins evolved uniquely in reptiles and birds, forming scales, claws, beaks, and feathers.
7 citations,
October 2018 in “BMC genomics” Key genes can rewire networks, changing skin appendage types.
68 citations,
April 2014 in “Journal of Investigative Dermatology” Trichohyalin-like proteins are essential for the development of skin structures like hair, nails, and feathers.
788 citations,
February 2007 in “Nature” The document concludes that skin stem cells are important for hair growth and wound healing, and could be used in regenerative medicine.
36 citations,
November 2019 in “Molecular biology and evolution” Cysteine-rich keratins evolved independently in mammals, reptiles, and birds for hard skin structures like hair, claws, and feathers.
22 citations,
December 2016 in “PloS one” A specific protein in chicken embryos links early skin layers to feather development.
3 citations,
October 2022 in “PloS one” Scientists have developed a method to keep chicken feather follicles alive and structurally intact in a lab for up to a week.
4 citations,
June 2023 in “Journal of developmental biology” The skin systems of jawed vertebrates evolved diverse appendages like hair and scales from a common structure over 420 million years ago.
17 citations,
June 2012 in “Journal of experimental zoology. Part B, Molecular and developmental evolution” Hair in mammals likely evolved from glandular structures, not scales.
