Resurrecting Lost Worlds
- “…The Kashmiri red stag has been listed as a critically endangered species by the IUCN for decades… In the early 1990s, the number of red stags was estimated to be around 5,000 but dramatically decreased to about 150 in 1970 and around 110–130 in 2015…”
- “… 58 animals have become extinct in Australia since European settlement.. And many more are in danger of becoming extinct…..”
- “…Estimates place the total wild population of the lion-tailed macaque of the western ghats of south India around 4,000 individuals, and is projected to decline more than 20% in the next 25 years should threats like hunting, roadkill, and habitat loss persist…”
And, the list continues…
How many species do you think we have on our planet? And how many are we losing as a result of anthropogenic activities?
Well, this is a tough question to answer.
Our world is quite complex, and science has facilitated the discovery of new species every day. A multitude of species still need to be discovered, making the process of quantifying biodiversity loss practically impossible.
- To illustrate the degree of biodiversity loss we’re facing, let’s go through a scientific analysis…
- Experts estimate the rapid loss of species we are seeing today to be between 1,000 and 10,000 times higher than the natural extinction rate.
- If there are 100 million different species co-existing with us on our planet — between 10,000 and 100,000 species are becoming extinct each year !!
We must take swift action to rescue and restore the endangered species without unnecessarily debating over the exact species numbers.
While nature conservationists are working tirelessly to conserve the remaining endangered species by employing manual methods like Fencing (habitat protection), Policies and Laws, monitored enclosure, controlling predators, etc., it is evident that these methods are inefficient given the severity of the crisis. Evidently, we need a more impactful and innovative approach to repair the ecological balance.
The advancements in synthetic biology have allowed experts from various fields, including conservationists, geneticists, and ethicists, to come together and find new solutions for averting this biodiversity crisis. Scientists have harnessed synthetic biology tools to create cutting-edge techniques like In vitro Fertilization and have successfully brought back species from the brink of extinction.
A remarkable example worth highlighting is that of the Northern White Rhinoceros (NWR), a subspecies on the edge of extinction with just two females remaining. A group of dedicated scientists utilized ‘invitro-fertilization’ and ‘embryo transfer’ techniques to artificially facilitate the production of offspring and ensure the continuation of this species. Given the infertility of the remaining females, a crucial step involved the artificial stimulation of ovaries in facilitating oocyte recovery. This was achieved through analogs of GnRH (gonadotropin-releasing hormone) in a method referred to as “ovarian super stimulation”. Once the ovaries began producing oocytes, a minimally invasive approach known as “transrectal ultrasound-guided follicular aspiration” was employed for ovum pick-up, demonstrating a procedure free of post-surgical complications.
Various in vitro maturation (IVM) protocols were tested to achieve mature eggs. The fertilized eggs were then grown to the blastocyst stage in vitro and strategically cryopreserved for later embryo transfer using spermatozoa obtained from deceased NWR males using the technique of “intra cytoplasmic sperm injection “.
Along with such artificial reproductive technologies, gene transfer methods like targeted genetic interventions (TGI) have emerged as powerful tools to recover endangered species by introducing genetic diversity in the population.
TGIs have enabled the editing of specific genes and confer species with vital traits like-
- More resistance to diseases
- Broader Dietary Adaptability
- Increased Resilience to Climate Change,
thereby increasing the chances of their survival.
The potential of TGIs extends beyond reviving animal species. A milestone in endangered species preservation was the production of American Chestnut trees with enhanced resistance to the blight fungus (Cryphonectria parasitica) responsible for the chestnut blight outbreak.
Before the early 1900s, chestnut trees abundantly flourished in North America’s forests; they formed an integral part of the ecosystem, providing shelter and food to many other creatures of the macro and microbiota. The accidental introduction of the fungus Cryphonectria parasitica imported from Asia, caused a deadly blight disease that spread like wildfire, eradicating billions of them.
Many attempts were made to find ways to revive the plant. Initially, scientists sought to tap into the natural resistance in the Chinese chestnut and attempted interbreeding with the American chestnut. However, this approach was rooted in an erroneous assumption that blight resistance could be attributed to a mere 1 or 2 genes, which is now understood to be more complicated, involving 9 different chromosomes. And traditional breeding methods lead to the development of undesired traits like male sterility.
Due to these challenges, the scientific focus shifted to attempts at gene editing. Recognizing that the fungus’s oxalic acid production caused the blight, researchers began looking for genes that may guard against this compound. Finally, they landed on a gene from a wheat plant that codes for a protein capable of breaking down the acid into a non-toxic product. With successful gene transfer achieved using a bacterial vector to introduce this crucial gene into the plant’s ovaries, genetically modified trees with enhanced resistance were cultivated and placed in the field in 2006. If approved by the US authorities, this initiative will become the first genetically engineered forest tree species to be introduced in the wild.
Apart from these techniques that are being used for the recovery of endangered species or to save the species from the brink of extinction, there is another developing field of research, which has personally fascinated me to know more about, which tries to bring back extinct species. “De-extinction” is the process of creating an organism that is — or greatly resembles — a member of an extinct species.
In 2013, de-extinction became widespread; National Geographic devoted a cover story to this topic. The article included various possibilities and scenarios about the most suitable candidates for reviving from the past.
Also, the International Union for the Conservation of Nature (IUCN) published the Guidelines on Reintroduction with a list of 20 “most suitable faunal candidates” and recommendations for risk evaluation. On this list, the most numerous were mammals, followed by birds and an insect.
De-extinction generally refers to reviving animals rather than plant species. Efforts have already been made for iconic animal species such as the woolly mammoth, the moa, the Carolina parakeet, the passenger pigeon, or peculiar creatures like the gastric brooding frogs.
With all this said and done, let me take you through an engaging “woolly mammoth” case so that you can visualize what de-extinction is.
The project “Woolly Mammoth” was the idea of a Havard geneticist, George Church. A biotech company named Colossal, with a team of scientists, is working under his guidance to bring back the extinct mammoth by genetically modifying the “Asian Elephant”. This project, leading the charge to the world’s first species restoration, consists of 12 steps, ending with the birth of a woolly mammoth, which Colossal aims to achieve within the next 4 to 5 years.
12 steps in the wooly mammoth de-extinction process:
1) Collect Asian Elephant DNA
2) Sequence the Elephant genome
3) Collect viable Woolly Mammoth tissue samples: there are well-preserved remains of the mammoth in the ice covers of Siberia, which are suitable for DNA extraction and sequencing.
4) Sequence the Woolly Mammoth genome
5) Identify traits to edit within the Asian Elephant genome: traits that will enhance the ability to resist the cold, like smaller ears, shaggy fur, etc.
6) Build CRISPR libraries that will help edit the above-identified genes of the Asian Elephant.
7) Insertion of CRISPR libraries: insert the modified cold-resistant genes into the genome of Asian Elephants.
8) Verify that the cold-resistant genes are expressed in the hybrid cells: this includes various assays, qualitative and quantitative testing for the expression of the required genes.
9) Embryo transfer uses SCNT (somatic cell nuclear transfer). After it is confirmed that all the required genes are functional in the hybrid genome, the nucleus from an Asian elephant egg cell is replaced by the hybrid nucleus. Electric pulses are given to stimulate division and embryo development.
10) Implantation: after the embryo is developed in vitro, it is transferred to a surrogate African Elephant.
11) Gestation: around 18 to 22 months in the African Elephant species.
12) Birth of the woolly mammoth: the newborn will be a hybrid with the traits of the extinct wooly mammoth.
Although it sounds like fiction, this project is already in the process of implementation. De-extinction raises ethical concerns regarding long-extinct animals co-existing with the present species and causing an ecological disbalance. This practice also prompts comparisons with humans playing god-like roles in altering nature. There could be potential unforeseeable consequences of the reviving of extinct species, they could be incompatible with their habitat, and disrupt ecosystems. Potentially putting the planet in turmoil. We should also consider the possibility of these new organisms causing the extinction of already existing species. We also need to find out whether these organisms will be able to live in the current conditions of the planet, which are different from the ones that were present in the past.
The idea of de-extinction is interesting, and this may become the only option left to save the planet’s biodiversity if things go further out of hand. The success of this project would be an accomplishment for science and would change the world in many positive ways. But in the present situation, considering all the possible consequences, the only question is, “We can, but should we?”
References:
- https://doi.org/10.3325%2Fcmj.2014.55.423
- https://earth.org/endangered-species-in-india/#:~:text=Snow%20Leopard,to%20about%20500%20in%20India.
- https://wwf.panda.org/discover/our_focus/biodiversity/biodiversity/
- https://doi.org/10.1007%2F978-1-4419-6518-9_7
- https://research.csiro.au/synthetic-biology-fsp/wp-content/uploads/sites/140/2020/12/20-00390_LW_INFOGRAPHIC_SynBioSurveyGraphics_Conservation_A4_WEB_201118.pdf
- https://massivesci.com/articles/chestnut-tree-genetic-engineering-blight-fungus-resistance/
- https://link.springer.com/article/10.1007/s11056-016-9561-5
- https://doi.org/10.1016/j.theriogenology.2009.06
- https://www.nature.com/articles/s41467-018-04959-2
- https://reviverestore.org/5-technologies-save-endangered-species/
- https://doi.org/10.3325%2Fcmj.2014.55.423
