The Genetic 'Switch" Behind Parrot Color Diversity

Scientists from the University of Hong Kong, alongside an international team, discovered a genetic "switch" that controls the diversity of vibrant colors in parents. The study, uploaded in the journal Science, showed that parrots use unique pigments called psittacofulvis to create their known distinctive colors of yellow, red, and greens. Other birds do not possess these psittacofulvin pigments. One protein, which is a type of aldehyde dehydrogenase (ALDH), is in charge of controlling these psittacofulvin pigments. The ALDH protein functions as a color dial, actively converting red psittacofulvins to yellow ones when cells produce them in high quantities. The mechanism of this process is demonstrated in multiple parrot species like the dusky lory, rosy-faced lovebirds, and budgerigars. The researchers also genetically engineered yeast to produce parrot colors, confirming that the found gene, ALDH3A2, is sufficient to explain how parrots control their feather coloration. This discovery sheds light on how complex traits can evolve through simple molecular innovations. I find this article very interesting as such simple molecular innovations in parrots allow them to allow biological switches to maintain the parrot's distinctive colors. Suppose animals such as parrots can create their biological dial to adjust the pigmentation of their feathers. Could humans have the same mechanism as a dial that helps control pigmentation in our hair or other body parts? With further research into this, I believe we could take another step forward in understanding biological mechanisms https://www.sciencedaily.com/releases/2024/11/241115125034.htm https://www.science.org/doi/10.1126/science.adp7710

Bird Beaks and Parrot Pigmentation

Authors Simon Griffith and Daniel Hooper make two very straightforward, yet interesting findings in their article "A single atom can change the colour of a bird. These are the genes responsible," published in the The Conversation. The findings are based off of two different research papers on pigmentation in birds, focusing on the biochemical reasons for different colors in Pseudeos fuscata, otherwise known as the Dusky Lory.

It turns out that two different genes are responsible for the red-to-yellow color range found these birds. These genes control a single enzyme, which converts red pigments to yellow. In the dusky lory, mutations in the genes cause the enzyme to become inactive, but only in certain parts of the bird. This is why some dusky lories have yellow beaks but red bodies; the genes in the beak cells are mutated, but not in the body cells.

Parrots are really unique in that their pigmentation come from psittacofulvins, a special pigment made by and found in parrots. Most other birds' pigmentation come from their food. I think that this makes parrots much more interesting to study, since their genetic basis for color can lead to much more variation among individuals. Perhaps different kinds of mutations in the dusky lory's genes can lead to more colors besides yellow and red. Albino individuals may also exist.

I also am curious to know whether or not different color variations may be favored by natural selection. Is a red beak more attractive? Does a yellow beak illness or weakness? As Griffith and Hooper write in their article, "[variation] can lead to the origin of a new species." Perhaps the the red beak and yellow beak birds with diverge with time. I think this is a question worth answering.

ARTICLES

https://theconversation.com/a-single-atom-can-change-the-colour-of-a-bird-these-are-the-genes-responsible-242685

https://schaechter.asmblog.org/schaechter/2022/08/psittacofulvin-pollys-peculiar-plumage-pigment.html

Loss of pigmentation in the skin due to the genetics: Vitiligo

     Vitiligo is a genetic condition that creates a loss of pigmentation in patches. Hair on these regions may also lose pigment and appear as white. This condition can appear at any age, and the size of the patches varies between individuals. Most commonly these patches can appear on the face, ears, scalp, and limbs. Although considered an autoimmune disorder, genetics do have a role in this condition. The inheritance pattern for this condition is more complex, as it can be passed down from parents to offspring, but that is not a guarantee as vitiligo can happen at any age at random.

    This condition is extremely fascinating as it has no effect on the individual other than loss of pigmentation. Studying this condition and find out if there’s a way to prevent this condition lies within the genome potentially. 

Link to article: https://medlineplus.gov/genetics/condition/vitiligo/#inheritance

Genes for Skin Color Variation

The biggest assumption for differences in race's arises from the color of skin a person may have.  This has been found to be an error by a research study published for the genetics of skin color in Africans.  This research study has found eight genetics variants of the human genome that strongly influence pigmentation.  Like other mammals, humans have melanosomes that are packed with pigment molecules (more pigment results in darker skin).  In order to discover the genes that produce pigments, those with European ancestry were studied and a mutation called SLC24A5 was the cause for paler skin.  African population on the other hand varies in skin color.  From a study of 1570 people from African countries, a set of genetics variants accounted for 29% of variations in color were discovered.  One variant MFSD12 affected skin color producing darker color.  Dr. Tishkoff and her team have found that variants for dark skin were inherited from an African population and that variations for lighter skin were introduced by interbreeding with Neanderthals.  

https://www.nytimes.com/2017/10/12/science/skin-color-race.html

http://science.sciencemag.org/content/early/2017/10/11/science.aan8433

Optix gene responsible for butterfly wing color

New genes are being discovered more frequently than ever. Scientists have found genes responsible for anything from your height to eye color. In regards to eye color, in humans, the genes associated with eye color can have mutations that cause different eye color (such as green eyes) or the absence of eye color (albinism). However, sometimes you want to change your eye color, perhaps you want to go bold and have purple eyes. So you get contacts. But what if there was a way to control what eye color you want? According to an article on The New York Times, scientists have located two "master genes" that are responsible for how butterflies get their wing color. One of these genes is called optix. It is the gene that is responsible for the pigmentation of butterfly wings. What scientists found was that if the gene was removed from the eggs of a certain type of butterfly, then there would be a different pigmentation in the wings of the butterflies. It was found that the melanin that was controlled by the optix gene created a different color, hinting to the idea that melanin is connected to the optix gene, and produced a different color. Scientists were also looking at gene called WntA, which is responsible for the patterns of the pigmentation to appear on the wings of butterflies. When this gene was deleted, then there was an absence of pigmentation in the patterns of the wings.

I personally find this study to be very fascinating. It makes me wonder if we would be able to do this with humans in the near future. However, I wonder if we would be able do this, would it be a cause for humans to have albinism, since the gene responsible for the melanin production in our eyes to become non-existent. I think it might become most likely become a very prominent phenotype if this would become successful, since the gene would have been removed entirely from original person. Overall, I find this study to be very interesting, and I wonder if similar procedures and experiments will be done in order to alter the appearance of humans and other animals.

CCMB Scientists Unravel Skin Colour Genetics of Indians

People who had a combination of homozygous mutant alleles of the new and the known SNP had the fairest skin 

A study of skin colour of 1,167 people belonging to 27 ethnic groups living in Uttar Pradesh and Bihar found that social structure defined by the caste system has a “profound influence on skin pigmentation”. The skin colour was found to vary significantly among ethnic groups and social categories studied.

Accordingly, Brahmins of Uttar Pradesh have the fairest skin while Manjhis (Majhwars) have the darkest skin (highest skin pigmentation). Bhagats exhibit maximum variation in skin pigmentation. Four social groups — general, scheduled caste, other backward caste and religious group — were studied. The results were published in The Journal of Investigative Dermatology.
The association of rs1426654, a key single nucleotide polymorphism (SNP) in SLC24A5 gene, with skin colour has been well established. In fact, this SNP explains 25-38 per cent of pigmentation differences between Europeans and west Africans. “In addition to rs1426654, our study found another SNP (rs2470102) to be significantly associated with skin colour in the Indian population,” says Kumarasamy Thangaraj from the Centre for Cellular and Molecular Biology (CCMB), Hyderabad and the corresponding author of the paper.

The new SNP was found to independently affect skin pigmentation variation among the Indian population. While the well known SNP (rs1426654) has been found to have a significantly larger effect on skin colour ranging from Europeans to western Africans, the new SNP that the Indian researchers discovered is predominant in India/Asia. But both SNPs taken together are able to better explain the variation in skin colour among the Indian population than each of the SNP individually. The two SNPs together account for over 38 per cent of the variability in skin colour in the Indian population. The researchers compared the skin colour with the genotype of the individuals. Homozygous (similar) mutant alleles tend to cause lighter skin colour while homozygous wild alleles tend to cause darker skin colour. “So those with homozygous mutant alleles of the new SNP had fairer skin compared with those who had homozygous wild type alleles,” he says. The difference in skin colour persisted even when the contribution by the well known SNP was adjusted. “This shows that the new SNP has an independent effect on skin colour,” says Dr. Thangaraj.

People who had a combination of similar (homozygous) mutant alleles of both the new and the known SNP had the fairest skin; they are said to belong to the H1 haplotype. The frequency of the H1 haplotype was far higher (96 per cent) in people with lighter skin than in darker skin (37 per cent). “A particular haplotype is not exclusive to a social category. Though the frequency is less, we do find H1 haplotype in dark skinned social category. This is why we have fair-skinned people even in the dark skin social category and dark-skinned people in the otherwise fair skin social category,” he says.
In a subsequent study, Dr. Thangaraj and his team genotyped 1,825 individuals belonging to 52 diverse populations in India. They found the allele frequencies of the two SNPs were similar among the Indian population and spread across the population. “Like in Uttar Pradesh and Bihar, the proportion of both mutant and wild homozygous alleles is distributed in differently frequencies in different populations across the Indian population. Also, the H1 haplotype was not exclusive to any particular population or social category,” he says.

The study found that ultraviolet radiation-based selection model alone cannot account for the entire range of variation in skin colour seen in the Indian population. Rather, it is interplay between selection pressure for lighter skin in response to relatively less sunlight and admixture of the two founding populations of India.