Top 10 Curiosities about DNA: part II - ADNTRO

Top 10 curiosities about DNA: part II

DNA is one of the most intriguing molecules out there, as it contains all the information necessary to make us who we are. In the previous article we saw some curious facts about its size, about how the human genome was sequenced for the first time and how much it resembles that of other species, and also about genetic fingerprinting and sex-linked diseases. Continue exploring this fascinating molecule with ADNTRO.

6. Earth Biogenome Project

In July 1995, the complete genome of an organism, the bacterium, was sequenced for the first time. Haemophilus influenzae. Since then, and thanks to the rapid advance of massive sequencing techniques, it has been possible to sequence the entire genome of almost fifteen thousand eukaryotic and prokaryotic organisms.

Recently, an international consortium of scientists has proposed what may be the most ambitious project in the entire history of biology, called Earth Biogenome Project. The initiative consists of sequence, catalog and analyze the genomes of eukaryotic species (except for bacteria and archaea), a task that according to experts can be completed in ten years with a budget of 4.7 billion dollars.

Estimates indicate that there are between ten and fifteen million eukaryotic species of plants, animals and fungi on Earth, but only two million of those species are actually known, so the Earth Biogenome Project would imply a complete transformation of our scientific understanding of Life on earth.

7. Curious gene names

Our genome is made up of more than twenty thousand genes, but How is a gene named when it is discovered? There are only two general rules, the first, not to name the discoverer, tempting as this may be, and the second, to try to put a name that refers to the function of that gene.

These broad rules allow you to unleash your imagination and play with double meanings. Thus, they exist genes with the most diverse names. For example, the discoverers of a cancer-related gene named it POKEMON, which led to legal disputes with the Nintendo brand. The fruit fly is a gold mine when it comes to curious gene names. In it we find a gene called COITUS INTERRUPTUS, which makes intercourse last 40% less, and another called KEN AND BARBIE, which implies that the external genitalia do not develop. They both refer to the function of the gene, right?

8. Alana Saarinen, the girl with three parents

Alana Saarinen was conceived through fertility treatment pioneer in his time, called cytoplasmic transfer, which is currently banned and completely deprecated. Cytoplasmic transfer was initiated in the late 1990s in the United States and consists of transferring a part of the cytoplasm of a healthy oocyte to the cytoplasm of an oocyte that shows a decreased capacity for development. In the healthy cytoplasm to be transferred there are, among other cellular organelles, the mitochondria, which have their own DNA, and which is different from the DNA contained in the cell nucleus. This causes the resulting cytoplasm to have its own mitochondrial DNA and external mitochondrial DNA, from the donor.

Because mitochondrial DNA is inherited exclusively through the mother, Alana Saarinen would have genetic information for two mothers and one father. It is estimated that between 30 and 50 babies have been born worldwide through the cytoplasmic transfer technique, which is why they carry the DNA of three parents. If Alana had female offspring, her daughter would inherit her unusual genetic code, with the possible implications that this entails.

Although cytoplasmic transfer has not been performed in years, a technique called mitochondrial replacement, based on using donor mitochondria to avoid so-called mitochondrial diseases, which are rare, but quite serious. If this technique is approved and used, we would again find babies with three genetic parents.

9. History of man through genetics

Evolution and genetics They are two interconnected branches of science, since the first is produced through the second. In other words, the evolution is the process of change of organisms through genetic mutations involving variation in populations. The environment interacts with these variations by selecting those individuals that best adapt to their environment, who will have more offspring and will be able to evolve into new species. 

The archaeological sites of Atapuerca, in Burgos, are a benchmark in the study of prehistory and human evolution, since from them more than 90% have been obtained from the hominid fossil records from all over the planet. In addition, these remains belong to very different time periods, the oldest dating from 1.4 million years ago, and the most recent from the Middle Ages.

The comparative genomics is a powerful tool for the study of human evolution. Through the analysis of fossil remains, and the changes experienced in the genomes through time, space, and even culture, it has been possible to clarify many very relevant questions to understand the history of man, which goes back hundreds of years. thousands of years ago. Some of the achievements that have been made in this field thanks to genetics are:

  • Understand how the appearance, behavior, and biology of different hominin species have changed over time.
  • Estimate an approximate date for different relevant events that took place hundreds of thousands of years ago, such as the time when the ancient predecessors of humans separated from those of Neanderthals.
  • Generate hypotheses about the migrations of human beings in prehistory.

10. HeLa cells

Henrietta Larks was born on August 1, 1920 in the state of Virginia. A descendant of slaves, African American, and a humble family, Henrietta has saved countless lives, generated millions of dollars and marked a before and after in the history of biology and genetics. As if that were not enough, all this he achieved after dying at 32 years of uterine cancer.

The history of the famous Henrietta Larks cells, commonly called HeLa cells, begins in 1951, the day that Jon Hopkins went to the hospital to consult and treat a tumor that he suffered in the cervix. The doctors took a biopsy of the carcinoma that suffered, to diagnose the cancer, until now a standard procedure. However, they subsequently used Henrietta's samples for research and personal projects, without ever asking for her consent.

They achieved an unprecedented feat, which consisted of keeping human tumor tissue in culture indefinitely, thus obtaining the first and only immortal cell line that has been achieved to date. Normally, the maximum number of cell divisions that cells can achieve is around 50 (a phenomenon known as the Hayflick limit). However, Henrietta's cells were and still are capable of dividing without limits. And not only that, but they grow very quickly, being able to double their number in 24 hours.

Henrietta's family did not discover the incredible capacity of immortal cells until after 20 years, and they never received any kind of benefit. It is difficult to explain the importance that HeLa cells have had in biomedical research for the last seventy years. An example, if we type in Pubmed (one of the most used scientific search engines) "HeLa", more than 120,000 results come out. Furthermore, HeLa cells were sent into space. They have even played a relevant role in the development of the COVID-19 vaccine, as they have provided information on the molecular mechanics of SARS-CoV-2019 and the components necessary for infection. In case you want to know more about Henrietta's life, there is a documentary about her, titled "The Immortal Life of Henrietta Larks."

To keep discovering things about your own DNA molecules We invite you to undertake this journey with ADNTRO.

Bibliography

Books:

  • Rosa García-Verdugo, “Genetics is you”. Editorial Paidós, 2020.
  • Sergio Parra, "That WAS NOT in my GENETICS BOOK". Editorial Guadalmazán, 2020.

Articles:

  • Juan Pablo Álvarez A., “Henrietta lacks. the name behind hela cells, the first human immortal cell line ”, Los Condes Clinic Medical Journal, pages 726-729 (July 2013). DOI: 10.1016 / S0716-8640 (13) 70214-1
  • Raúl Eduardo Piña-Aguilar, "The return of the oocyte: from the forgotten cytoplasmic transfer to the current transfer of the meiotic spindle", Mexican Journal of Reproduction Medicine, 2012; 4 (3): 132-138

Web resources:

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