One of the painters whose life and work is most deserving of greater attention is Vincent van Gogh (March 30, 1853 – July 29, 1890). And not only from the pictorial-artistic perspective, but also from others like a medical perspective, as he tried to shed light on a variety of health problems, especially the mental problems that afflicted him. Or from a chemical-physical perspective; for example, research on the composition of his palette of colors, and how it affects the evolution of colors in his paintings – at the expense of possible acts of vandalism. But also some of his greatest works such as Sunflowers and Starry Night, have led to interesting analysis from a genetics perspective.
MUTANT SUNFLOWERS
Some of the flowers that he depicted in his masterpiece Sunflowers are strange. Next to the sunflowers with a normal shape, he represented two other variants with the inflorescence consisting of an external yellow part (which are really sterile flowers) and another internal dark part (comprised of fertile flowers). One in which the internal area is very small, with practically the entire inflorescence consisting of sterile yellow flowers, which are called the double flowers variant. And there is another variant on the opposite side where the yellow area is very small. It is called a tubular type due to its shape.
The origin of these variants must be very old, and they were grown because they add floral diversity and beauty. In fact, van Gogh must have noticed them for precisely this reason. But the scientific foundation of these variants has remained a mystery until well into the 21st Century. In fact, until 2012, when scientists from the University of Georgia in Athens, Georgia (U.S.) carried out a variety of experiments that shed light on this.(1).
First, they used the method that a peer of Van Gogh, the founding father of genetics, Gregor Mendel (20 July 1822-6 January 1884), used to clarify the reasons for the variations in another plant, the pea plant. In other words, they crossed three types of sunflowers. And reached the conclusion that these variations behaved as if they were due to mutations in a single gene in which three alternatives exist, what genetics calls alleles. One that we could call a normal allele that results in normal flowers; another that results in inflorescences called double flowers; and a third that results in tubular inflorescences. And they also saw that the first and second allele are co-dominant, so that when one plant carries both, it has floral structures from both. On the other hand, both are dominant over the third type of allele, so that when a plant has any of the first two alleles, as well as the third, it is not expressed in the phenotype.
Then, using molecular tools, they were able to characterize the gene involved in these variations and how they originate. It is a gene that intervenes in the formation of the inflorescence of the sunflower in a way that during normal development, it is expressed in the external part, resulting in the sterile yellow flowers, while it is repressed in the internal part. On the other hand, in the mutants with double flowers, this gene is expressed in both the external and internal parts of the inflorescence. And in the mutant tubulars, it is only expressed on the edge of the external part.
Finally, they eventually clarified that the double flower mutant allele is due to the fact that a fragment of DNA from nearly 1,000 pairs of nucleotide base pairs were introduced in the regulating area of the gene. This determines that the expression of the gene is changed during development, expressing itself in not only the outside of the inflorescence, but also in the inside. Meanwhile, the tubular mutant is due to the fact that in addition to the first insertion, there was a second – this time in the gene – of a fragment of DNA slightly larger than the first. As a result, the gene is only expressed on the edge of the inflorescence and therefore determines that few yellow structures appear.
And in terms of the nature of these insertions, while the first is a normal sequence of DNA, the second is a transposon. Something that in the end, thinking about it, takes us to the genes of the pea plants studied by Mendel, as it was later clarified that his famous mutant that resulted in the rough seeds were also due to a transposable element.
THE ‘VAN GOGH’ GENE
Continuing with the “genetic angle” of Van Gogh, a gene was named after him whose mutations result in the appearance of morphological variations, among other characteristics, in organisms that look like some figures in his paintings.
Above all, they are pictorial shapes that he portrayed in another one of his masterpieces, Starry Night. Specifically, in this painting, he included in the night sky several stars – including Venus and the Moon – with very characteristic swirling shapes. For this reason, when mutations were found in the fruit fly in which the chaetas that cover the wings adopt very similar configurations, this gene was given the name of the great Dutch painter (the gene is called ‘Vang’, his acronym). It was later discovered that this mutation can occur in organisms and can have more severe effects on development, even on humanity. (2).
And it was recently proven that these swirling shapes can also appear in the microbial world. These structures appear in cultures of the Myxococcus xantus bacteria. Specifically, the culture of mutants of this bacteria for a gene that influences cell division determines that the bacteria associate with each other, leading to a variety of shapes, some of which are very similar to the swirls that Van Gogh depicted in Starry Night.
XANTHOPSIA?
But what is the reason that all of these strange shapes appear in his paintings, or his “love” for the color yellow, which is ubiquitous in some of his most emblematic paintings?
Autor: Diego Delso
It has been extensively discussed that Van Gogh could have some kind of genetic anomaly in his vision of colors. For example, it has been analyzed whether he could be color-blind, but it does not seem very likely. It seems more plausible that he had an anomaly called xanthopsia– from xantho, meaning yellow – in which perception of the color yellow predominate. However, although this anomaly can be genetic as some cells of the retina are altered, it can also be due to environmental factors. For example, it can appear as a side effect from some medications like digitaline. In the case of Van Gogh , it is not clear whether his possible xanthopsia was the result of genetic or environmental factors, as he was treated with medical principles like the one mentioned earlier and/or he could have been contaminated by different components from his paints (3).
Manuel Ruiz Rejón
Genetics Professor at the University of Granada, the Autonomous University of Madrid
and co-author of the book ‘La Herencia del Mendelismo’ (The Legacy of Mendelism).
BIBLIOGRAPHICAL REFERENCES
- Chapman M.A. et al. 2012. Genetic analysis of floral symmetry in Van Gogh’s sunflowers…PLoS Genet. 8(3): e1002628.
- Kibar, Z. el al. 2007. Mutations in VANGL1 associated with neural tube defects. N. England. J. Med., 356:1432-37.
- Demir, D. Gorkey, S. 2018. Van Gogh and the obsession of yellow: style or side effect. Eye (Nature), 33: 165-66.
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