Arxiu d'etiquetes: cloning

From lab to big screen (II)

As I told you in the previous article on genetics and cinema, there is a wide variety of films that talk about genetics. In the next article we will talk about science fiction, with two well-known films. Beware: spoilers!

GATTACA (1997)

Director: Andrew Niccol

Cast: Ethan Hawke, Uma Thurman, Jude Law

Genre: Science fiction

Story line: Vincent is one of the last “natural” babies born into a sterile, genetically-enhanced world, where life expectancy and disease likelihood are ascertained at birth. Myopic and due to die at 30, he has no chance of a career in a society that now discriminates against your genes, instead of your gender, race or religion. Going underground, he assumes the identity of Jerome, crippled in an accident, and achieves prominence in the Gattaca Corporation, where he is selected for his lifelong desire: a manned mission to Saturn’s 14th moon (titan). Constantly passing gene tests by diligently using samples of Jerome’s hair, skin, blood and urine, his now-perfect world is thrown into increasing desperation, his dream within reach, when the mission director is killed – and he carelessly loses an eyelash at the scene! Certain that they know the murderer’s ID, but unable to track down the former Vincent, the police start to close in, with extra searches, and new gene tests. With the once-in-a-lifetime launch only days away, Vincent must avoid arousing suspicion, while passing the tests, evading the police, and not knowing whom he can trust.

Relation with genetics: GATTACA is the “genetic” film par excellence. Starting with the title, this is formed by the initials of the four nitrogenous bases that make up DNA (guanine, adenine, thymine and cytosine). In addition, the helical shape of the DNA is repeated in several moments of the film, as in the stairs of Vincent’s house.

The main issue is about genetic selection, all children born have been genetically selected, closely linked to bioethics. The idea of ​​this selection is to reach eugenics, that is, to improve the population by selecting the “best” humans. This concept can be related to the Hitler’s Germany, who believed that Germans belonged to a superior group of races called “Aryan”. Hitler said that German Aryan race had been better endowed than the others and that this biological superiority destined Germans to oversee an empire in Eastern Europe.

Although nowadays genetic selection is valid and is used to avoid diseases, it is not applied with the same purposes as those of the film. At present, it is decided to carry out genetic selection after having studied the family and carried out the appropriate genetic counselling. It aims to help patients and their families avoid the pain and suffering caused by a genetic disease and should not be confused with the eugenic objective of reducing the incidence of genetic diseases or the frequency of alleles considered to be deleterious in the population.

This is very related to the genetic discrimination, case also exposed in the film. Gattaca is situated in a possible future in which genetics, trying to improve the quality of life of society, causes a movement of discrimination.

When we talk about discrimination, we tend to think about racial discrimination. This is defined as the different or exclusive treatment of a person for reasons of racial or ethnic origin, which constitutes a violation of the fundamental rights of individuals, as well as an attack on their dignity. Racism has been present throughout the history of mankind, especially in the twentieth century with racial discrimination in the United States and apartheid in South Africa.

For some time now, genetic discrimination has been gaining weight. It happens when people are treated differently by their company or insurance company because they have a genetic mutation that causes or increases the risk of a hereditary disorder. Fear of discrimination is a common concern among people who undergo genetic testing, and is a current problem that concerns the population because your own genome does not have to be a curriculum vitae that opens or closes doors as happens in the film. Vincent goes to work in Gattaca after performing a urine test and a blood test, since in Gattaca they do not choose workers for their ability or ability but for their DNA.

However, the film ends with the sentence “There is no gene for the human spirit”. This means that, although the society in which Gattaca is located is based on genetic modification, it does not affect the morality and final character of people because there is no way to genetically relate to the spirit, only the body has the genetic information.

Video 1. Trailer Gattaca (Source: YouTube)

JURASSIC PARK (1993)

Director: Steven Spielberg

Cast: Sam Neill, Laura Dern, Jeff Goldblum

Genre: Science fiction

Story line: Huge advancements in scientific technology have enabled a mogul to create an island full of living dinosaurs. John Hammond has invited four individuals, along with his two grandchildren, to join him at Jurassic Park. But will everything go according to plan? A park employee attempts to steal dinosaur embryos, critical security systems are shut down and it now becomes a race for survival with dinosaurs roaming freely over the island.

Relation with genetics: In the first film of this saga, from dinosaur’s fossils scientists extract DNA to be able to clone dinosaurs. The cloned dinosaurs will be part of the Jurassic park on which the film is based.

It is true that DNA can be extracted from bones, widely used in forensic genetics. Same as the issue of cloning, which was known by the Dolly sheep, the first large animal cloned from an adult cell in July 1996. But the film goes further and raises the possibility of reintroducing, in today’s world, extinct species and challenge natural selection.

Video 2. Trailer Jurassic Park (Source: YouTube)

REFERENCES

MireiaRamos-angles2

How is genetic engineering done in plants?

For years, by crossing, scientists have achieved plants with a desired characteristic after many generations. Biotechnology accelerates this process and allows to catch only the desired genes from a plant, achieving the expected results in only one generation. Genetic engineering allows us to do all this. In this article I will explain what it is and how does it work.

WHAT IS GENETIC ENGINEERING?

Genetic engineering is a branch of biotechnology that consists in modifying hereditary characteristics of an organism by altering its genetic material. Usually it is used to get that certain microorganisms, such as bacteria or viruses, increase the synthesis of compounds, form new compounds or adapt to different environment.

It is a safer and more efficient tool for improving species than traditional methods (crossing) as it eliminates much of the randomness. On the other hand, modern biotechnology also becomes a new technology that has the power to modify the attributes of living organisms by introducing genetic material prepared in vitro.

It could be defined as the set of methodologies to transfer genes from one organism to another and express them (to produce proteins for which these genes encode) in different organisms of the original organism. DNA which combines fragments of different organisms is called recombinant DNA. Consequently, genetic engineering’s techniques are called recombinant DNA techniques.

Currently there are more plant organisms genetically modified than animal organisms. For this reason I will explain genetic engineering based on plants.

GENETIC ENGINEERING vs. TRADITIONAL METHODS

This methodology has 3 key advantages compared with traditional methods of genetic improvement based on hybridization:

  • The genes could come from any specie (for example a bacteria’s gene can be incorporated in soy‘s genome).
  • At genetically improved plant you may introduce a single new gene preserving the remaining genes from the original plant to their offspring.
  • This modification process delays less the deadlines than improvement by crossbreeding.

With this way you can modify properties of plants more broadly, more accurate and faster.

In traditional crossing it generates a hybrid which combines randomly genes of both parental organisms, including the gene of interest encoding the desired trait. In contrast, biotechnology techniques only pass one or few genes which encode a specific trait known. The new plant has all the original genes of the plant and an introduced gene accurately and directed (Figure 1).

fig1ENG
Figure 1. (A) Traditional method where, by crossing, a new variety is obtained. This carries the gene of interest (red), but also another genes randomly. (B) With genetic engineering we obtain a new variety of commercial plant with the gene of interest (red) of any other species (Source: Mireia Ramos, All You Need is Biology)

METHODOLOGY OF GENETIC ENGINEERING

Obtaining a transgenic organism through genetic engineering techniques involves the participation of an organism who gives the gene of interest and a receptor organism who will express the desired quality. The steps and the process techniques are:

0/ DECIDE THE AIM: MAKE KNOCK IN OR KNOCK OUT

KNOCK OUT:

This technique is to remove the expression of a gene, replacing it with a mutated version of itself, this being a non-functional copy. It allows the gene is not expressed.

KNOCK IN:

It is the opposite of the knock out process. A gene is replaced by a modified version of itself, which produces a variation in the resulting function of it.

In medicine, the knock in technique has been used as a strategy to replace or mutate genes that cause diseases such as Huntington’s chorea, in order to create a successful therapy.

1/ DOUBLE CHECK THAT THERE IS A GENE CODING FOR THE CHARACTERISTIC OF INTEREST

Firstly, you have to check the characteristic of interest comes from a gene, as this will be easier to transfer to a living organism that does not.

2/ CLONING THE GENE OF INTEREST

It is a complex process, but outline the steps are the following:

  • Extract DNA
  • Find a gene among the genes of this DNA
  • Sequence it
  • Build the recombinant vector

The DNA of interest is inserted into a plasmid, a circular DNA molecule with autonomous replication. The plasmids of bacterial origin are the most used (Video 1).

Video 1. “Clonación de un gen en un plásmido vector”. Explaining the use of plasmids as a vector in the process of cloning (Source: YouTube)

The development of these techniques was possible by the discovery of restriction enzymes. These enzymes recognize specific sequences and cut the DNA by these points. The generated ends can be sealed with ligase enzyme and to obtain a new DNA molecule, it called recombinant DNA (Figure 2).

adnrecombi
Figure 2. (1) Plasmid’s DNA (2) DNA from another living organism (3a, 3b) The restriction enzyme cuts DNA (4) The restriction enzyme recognizes AATT sequence and cuts between A and T nucleotides (5) The two DNAs are contacted with the purpose of forming recombinant molecules (6) A ligase enzyme joins the DNA ends (Source: GeoPaloma)

3/ CHARACTERISE GENE OF INTEREST

If we know the gene sequence we can compare this sequence with known gene sequence through bioinformatics, provided to determine which gene looks and assign a possible function. So when we have predicted the function of cloned gene we confirm it in vivo, usually transferring it to a model organism.

4/ MODIFY GENE OF INTEREST

We can add (promoter, introns…) or mutate sequences inside the encoding region.

5/ TRANSFORMATION OF A LIVING ORGANISM WITH GENE OF INTEREST

When we have finished the gene building with the desired gene and the promoter, the recombinant DNA is inserted into the cells of the living organism that we want to modify.

6/ CHARACTERIZATION GMO

When we already have the GMO (Genetically Modified Organism) it is analysed from the molecular and biological point. In the molecular analysis it must demonstrate if you have one or more copies of the transgene or how and what tissues the gene is expressed. In the biological analysis it looks if it achieves the objective for which it was designed.

REFERENCES

MireiaRamos-angles

The thylacine: we extinguished it

Today marks 79 years of the death of the last known thylacine, Benjamin, at the zoo in Hobart (Tasmania). The thylacine, Tasmanian wolf or Tasmanian tiger is one of the classic examples of extinct animals by humans. Its fame is due to its relatively recent extinction, its strange anatomy and the existence of videos of the last thylacine, which transmits certain uneasiness to know that no longer exists. Do you want to know their characteristics, the causes of their disappearance and their cloning project?

THE THYLACINE, A MARSUPIAL

Despite its many names, the thylacine (Thylacinus cynocephalus*) was not related to wolves or tigers (placental mammals), as it was a marsupial animal. Marsupials are a mammals’ infraorder in which the young is born at a very early stage of development, almost in embryonic state. The best known representatives are kangaroos, koalas, wallabies, possums and bandicoots.

Un dels pocs llops marsupials que es conserven taxidermitzats en el món. Museo nacional de Ciencias Naturales, Madrid. Foto: Mireia Querol
One of the few preserved thylacine taxidermy in the world. Museo Nacional de Ciencias Naturales, Madrid. Photo: Mireia Querol

After a very short gestation, newborn moves to one of the mother‘s nipples where is seized several months. In most marsupials, nipples, -and therefore the newborn- are protected by a pouch. When the brood completes its development, it will release the nipple and leave the pouch to explore the outside. Look in the following video the birth and migration of the embryo of a red kangaroo:

DESCRIPTION

The thylacine was native of Australia and Papua New Guinea, but in the seventeenth century (arrival of European settlers Oceania) was found only in Tasmania.

mapa tilacino, thylacine distribution, tigre de tasmania, lobo de tasmania
Old thylacine distribution. Map by Discover Life

It was an animal with physical traits of wolf, tiger and kangaroo due to convergent evolution, which made him a unique case and an enigma to science before their taxonomy was known. Its closest relative is the Tasmanian devil (Sarcophilus harrisii).

He looked like a big dog with a thick, stiff tail. Its weight was about 30 kg on average. The fur was short, gray-brown with 13-20 vertical black stripes at the rear. It is estimated that lived between 5 and 7 years in the wild.

Instal·lació d'exemplars dissecats. Foto: South Australian Museum
Display of taxidermy thylacines. Photo: South Australian Museum

It was capable of bipedal jumps and upright posture for short periods of time. They were also good swimmers. The anatomy of the thylacine when stood up, with its tail resting on the ground, reminds the kangaroo as evidenced by the following filming of 1933:

FEEDING

The thylacine was exclusively carnivorous, feeding on kangaroos, emus, wallabies and wombats. It was a solitary and crepuscular hunter who caught their prey by ambushes, as it was not very fast. It could turn the palm of the leg up like cats do. This increased movement of the leg would have allowed them subdue prey more easily after a surprise attack. In contrast, animals with reduced mobility in the leg, as some canines, prefer the persecution of the ambush and often hunt in herds.

Benjamin abriendo la boca en una respuesta a una amenza similar a un bostezo. Zoo de Beaumaris, foto de David Fleay.
Benjamin gasping similarly to yawning in response to a threat. Hobart Zoo. Photo by David Fleay.

Another unique feature was the ability it had to open its mouth. Equipped with 46 teeth, its powerful jaws could be opened at an angle of 120 degrees, allowing him to swallow large chunks of meat.

La impresionante capacidad bucal del tilacino. Foto: desconocido
The thylacine’s impressive buccal capacity. Photo: video capture by David Fleay

Look in the following video the last moving record of Benjamin (1933), from which was obtained the above screenshot:

To view the 7 videos that remain from this fantastic animal, enter The Thylacine videos.

REPRODUCTION

Thylacines could reproduce from June to December. It were born 2-4 pups per litter, who spent three months in the pouch but were still dependent on its mother‘s milk more than nine months. Unlike many marsupials, in the thylacine pouch opened to the rear of the body.

tilacino embarazada, cria tilacino
Only existing photographs of females with brood in the pouch. Photo taken from The Thylacine Museum

EXTINCTION

Australian Aborigines already knew and hunted the thylacine, as seen in their 1000 b.C art. The first possible thylacine footprints discovered by Europeans are from 1642, although it was not until 1808 that a detailed description of the species was made.

tilacino cazado
Thylacine hunted in 1869. Photo of public domain

There are several hypotheses that point to the extinction of the Tasmanian tiger, in the majority, humans are the main blamable. Like it happens nowadays in Spain, the Tasmanian wolf was quickly accused of killing cattle and hen, so despondent rewards were offered for the animal and was the subject of an intensive hunt. Later research has concluded that its jaw was not strong enough to kill an adult sheep.

Única imatge existen d'un llop marsupial amb una presa. Investigacions recents suggereixen que es tracta d'un muntatge amb un especimen dissecat per donar-li mala fama. Foto de H. Burrell
Only existing picture of a thylacine with a prey. Later research suggest that is a farce with a taxidermy specimen to give them bad reputation. Photo by H. Burrell (1921)

With the colonization of Australia, the habitat and prey of the thylacine were diminished drastically. They were also victims of introduced species on the continent by humans, such as dogs, foxes and dingoes (wolf subspecies). It is also probably that suffered some diseases that lead them to death.

ültimo tilacino salvaje cazado por Wilfred Batty. Foto: desconocido (Wikimedia commons)
Last wild thylacine hunted by Wilfred Batty (1930). Photo: unknown (Wikimedia Commons)

In 1920 the thylacine was already on the verge of extinction. In 1930, it was hunted by a farmer the last known wild specimen and in 1933 arrived at Hobart Zoo the nicknamed Benjamin. In 1936, he was forgotten outside his cage and did not survive the freezing temperatures at night. 59 days before, it had been approved officially the protection of the species.

Only 128 years after his “discovery” the last thylacine died. Photo by David Fleay colored by Neitshade

After the 50 years required by the scientific community without any sightings or evidence of its existence, the thylacine was officially declared extinct by IUCN in 1986. Many claim to have seen the thylacine and even filmed one in the wild, but there are no no definitive evidence.

CURRENT RESEARCH

The International Thylacine Specimen Database is an international database that compiles all existing records of the Tasmanian wolf (museum specimens, bones, photos, videos…). Since 1999, there have been attempts to bring the thylacine back to life by cloning techniques, which have been unsuccessful. In 2008, Australian scientists were able to extract DNA from specimens preserved in alcohol and activate a gene implanting it in a mouse embryo and in 2009 the complete sequencing of mitochondrial DNA was published. The elusive goal is to activate the complete genome of thylacine, to have a real possibility of cloning. But if that happens, what are the ethical, economic and scientific implications of the reappearance of an extinct species? The debate is still open.

*Thylacinus cynocephalus from greek θύλακος (thylakos, “pouch”) and κυνοκἐφαλος (kinokefalos, “dog-headed”).

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY