乌骨鸡

choi

(1) anatomy of a NORMAL bird feather (generally speaking).

feather
https://en.wikipedia.org/wiki/Feather
(section 1 Structures and characteristics: "A typical vaned feather features a main shaft, called the rachis. Fused to the rachis are a series of branches, or barbs; the barbs themselves are also branched and form the barbules. These barbules have minute hooks called barbicels for cross-attachment. Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap air and provide excellent thermal insulation")
(a) The English nouns barb, barbule (small barb), barbicel (even smaller barb) -- and barber -- are ultimately came from Latin noun feminine barba beard.  The accent in barbicel is in the first syllable.
(b) For an illustration of barbicel, search images.google with (barbicel Anatomy and Structure of the Fowl Springer Link) -- no quotation marks. The first or second return is it, from a book: Carmen R Parkhurst, Anatomy and Structure of the Fowl. Springer, 1988.

(2) It turns out to be oversimplified, for laypersons. Still the illustration gives you what "distant barbules" are, because it (the illustration) does not show "proximal barbules."  See next.
(a) Priscilla Gerber, Integumentary (Surface of the Bird). Poultry Hub, Nov 1, 2018
http://www.poultryhub.org/physio ... urface-of-the-bird/
("Barbicels or hooklets that hold the barbs together to form the vane. Each barb carries two rows of barbules. The distal row (those growing from that side of the barb facing towards the tip of the feather) has microscopic hooklets that hook onto the proximal barbules of the next barb. These hooklets are called barbicels. This interlocking gives a continuous, strong, smooth surface")
(i) Other than the quotation above, view figures 2 and 3 only.
(ii) Poultry Hub is published and maintained by Poultry CRC
https://en.wikipedia.org/wiki/Poultry_CRC
(2003- ; Headquarters  Armidale (approximately halfway between Sydney and Brisbane), New South Wales, Australia)
(iii) German-English dictionary:
* Gerber (noun masculine): "tanner"
https://en.wiktionary.org/wiki/Gerber

The German surname Gerber (presently used in nationalitoes: German, Swiss, and Jewish (Ashkenazic) ) is an "occupational name for a tanner, Middle High German gerwer (from Old High German (ledar) garawo leather preparer)." Dictionary of American Family Names, by Oxford University Press, 2003.
(b) two English adjectives: For proximal, see
proximate (adj): "immediately preceding or following (as in a chain of events, causes, or effects)   <proximate, rather than ultimate, goals — Reinhold Niebuhr>"
https://www.merriam-webster.com/dictionary/proximate

It is used in legalese: proximate cause, an element of negligence.

The adjective proximal (relative to distant) is used in anatomy.

choi

(1)
(a) "Their feathers lack functioning barbicels, and are thus similar to down on other birds. This characteristic leaves Silkies unable to fly."  en.wikipedia.org for "Silkie" (citations omitted).
(b) "Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap air and provide excellent thermal insulation."  en.wikipedia.org for "feather."

Of course I was doubtful that Silkie lacks only barbicels. It turns out, with more study on my part, that (1)(a) is correct, but (1)(v) is wrong. 乌骨鸡 father is neither normal ("wild type" in genetics jargon) nor downy.

(2) Ng CS and Li W-S, Genetic and Molecular Basis of Feather Diversity in Birds. Genome Biology and Evolution (published by Oxford University Press), 10: 2572–2586 (October 2018)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6171735/
(Introduction (the first 3 sentences): "Feather first appeared in dinosaurs in the Jurassic period, around 165–150 Ma (Xu et al 2014). One lineage of feathered theropod dinosaurs survived the mass extinction and became the ancestor of birds (Chatterjee 2015). Feather is believed to have evolved from scale, and novel scale-feather converters have just been identified (Wu et al 2018)" ) (citations are retained to show recent progress).

My comment:
(a)
(i) Other than the quotation above, view Fig 1(A) only, which displays "Downy feather," "Contour feather," and "Flight feather."
(ii) Lesson 2 Feathers. In Birds. Alaska Native Knowledge Network (ANKN), University of Alaska Fairbanks
www.ankn.uaf.edu/curriculum/units/birdslesson2.html

Quote:

"Activities: * * * 3) Select a large contour feather and a flight feather. a. Look at the vanes on these two feathers. How can YOU tell them apart? (The vane on the flight feather is wider on one side than on the other.)

"Types of Feathers: * * *
Contour feathers cover a bird's body * * * Though they appear to cover the entire body, contour feathers grow only in patches, called pterylae, on most birds' bodies. * * *
Flight feathers are the long feathers on the wings and tail used in flying. Wing flight feathers can be easily identified because the shaft does not divide the vane evenly.
Down feathers are the small fluffy feathers found under the contour feathers. What do people use down for? Birds use their down to keep warm, too. * * *"

(iii) For pterylae, see feather
https://en.wikipedia.org/wiki/Feather
(section 1.3 Distribution: a sketch with heading "Feather Tracts")
(b) in geology, for example: "Ages are abbreviated from Latin: Ga (giga-annum) is a billion years, Ma (mega-annum) is a million years, ka (kilo-annum) is a thousand years." from the Web.
(c) Theropoda
https://en.wikipedia.org/wiki/Theropoda
(from Ancient Greek [thḗr: Wiktionary] "wild beast" and "foot"/ section 3.3 Relations [you can see these dinosaurs were all bipedal] )

(3) Scientists from China Agricultural University 中国农业大学 (1905- ; public; based in Beijing) determined the gene mutation underlying Silkie chicken.
(a) Sequencing of chicken genome was completed in 2004, paid by National Human Genome Research Institute (NHGRI), US National Institute of Health. So after 2004, geneticists' job is to find the location, without having to sequence the locus first.
(b) Feng Chungang et al, A cis-Regulatory Mutation of PDSS2 Causes Silky-Feather in Chickens. PLoS Genet 10: e1004576 (2014)
https://journals.plos.org/plosge ... ournal.pgen.1004576

Abstract in toto: "Silky-feather has been selected and fixed in some breeds due to its unique appearance. This phenotype is caused by a single recessive gene (hookless, h). Here we map the silky-feather locus to chromosome 3 by linkage analysis and subsequently fine-map it to an 18.9 kb interval using the identical by descent (IBD) method. Further analysis reveals that a C to G transversion located upstream of the prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) gene is causing silky-feather. All silky-feather birds are homozygous for the G allele. The silky-feather mutation significantly decreases the expression of PDSS2 during feather development in vivo. Consistent with the regulatory effect, the C to G transversion is shown to remarkably reduce PDSS2 promoter activity in vitro. We report a new example of feather structure variation associated with a spontaneous mutation and provide new insight into the PDSS2 function")

Author Summary: " * * * Some chickens have silky-feather because of a loss of hooklets in pennaceous feathers * * * The causative mutation is located 103 base pairs upstream of the coding sequence of prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2). The expression of the PDSS2 gene is decreased in silky-feather skin during feather development in vivo. The silky-feather allele also reduces the PDSS2 promoter activity in vitro. This is the first report of feather structure variation associated with PDSS2 * * *

Introduction: " * * * The Silkie was first mentioned by Marco Polo in his Asian travelogues in 1298 as 'chickens with hair like cats that lay the best of eggs'. Darwin noted that the progeny from matings between Silkie and wild-type chickens did not show the silky-feather phenotype, and a recessive mode of inheritance was subsequently confirmed by Dunn in 1927. All chickens have similar downy feathers at hatching. The first molting is initiated a few weeks after hatching at which time down feathers are replaced with juvenile pennaceous feathers. In silky-feather chickens beginning with the first pennaceous feathers a clear difference in feather structure is seen as compared to wild-type, with the Silkie chicken maintaining a more downy appearance in the body contour feathers (Figure 1A and 1B)." (citations omitted).

Note:
(a) I only know Feng was in the lab of 胡晓湘 教授 (female), but I am clueless about the Feng's given name (his or her name in Chinese not found): whether Chung-ang or Chun-gang.
(b) Pennaceous feather is also known as contour feather. And plumulaceous feather, downy feather.

pennaceous (adj; from New Latin pennaceus, from Latin [noun feminine] penna [feather] + -aceus -aceous):
https://www.merriam-webster.com/dictionary/pennaceous

(c)
(i) title: "A cis-Regulatory Mutation"

Compare
(A) "Cis-regulatory elements (CREs) are regions of non-coding DNA which regulate the transcription of neighboring genes. * * * [in other words:] CREs are found in the vicinity of the genes that they regulate. * * * The Latin prefix cis means 'on this side [of; compare Latin prefix trans beyond, on the other side of],' ie on the same molecule of DNA as the gene(s) to be transcribed)  en.wikipedia.org for "cis-regulatory element."
With (B) "Trans-regulatory elements are genes which may modify (or regulate) the expression of distant genes. More specifically, trans-regulatory elements are DNA sequences that encode transcription factors." "en.wikipedia.org for "trans-regulatory element."

A promoter is a CRE in front of the coding sequence of a gene. Transcription factors bind to the promoter of a gene before transcription (ie, DNA to RNA)..
(ii) Abstract: "a C to G transversion"

[oint mutation
https://en.wikipedia.org/wiki/Point_mutation
(section 2.1 Transition/transversion categorization)

(d) Why the italics?  The in vivo and in vitro are Latin; as a foreign language (relative to English), they are italicized.
Submission Guidelines. PLOS | Genetics, undated
https://journals.plos.org/plosgenetics/s/submission-guidelines
("Nomenclature * * * Genes, mutations, genotypes, and alleles[:] Write in italics")

The Abstract has one sentence: "All silky-feather birds are homozygous for the G allele." Why is the "silky-feather" roman (ie, not italic)?  Because it is phenotype.  See roman type
https://en.wikipedia.org/wiki/Roman_type
(In Latin script typography, roman is one of the three main kinds of historical type, alongside blackletter and italic)