Tag Archives: biology

Do we get our genes from fish and mushrooms?!


Simple figure of how HGT occurs.

We acquire all our genes from our ancestors, right? Hmmm, maybe not. Recently, came across an article in the news expressing that we may have more than 100 genes from other species. You are probably wondering what the heck I am talking about. When we think of transferring genes, we imagine a family tree with branches pertaining to different members of the family, with a direct transfer of genes from parent to offspring. What we don’t consider at all is Horizontal Gene Transfer. This phenomenon, shortened to HGT, refers to when DNA is transferred between species through bacteria-infected viruses, genes that “jump” around cells and various other methods. The YouTube video below provides a quick summary of HGT with animations.

It is common to see this in action in single-celled organisms such as bacteria, where the foreign genes enter and get embedded in the recipient’s cell. However, recently scientists have found that this process occurs in animal cells as well. In this scientific article, Alastair Crisp and his research team examined HGT in detail in 26 animal species, including primates. Many genes, including the ABO blood group gene, were transferred to humans through other vertebrates. This article discussed more of Crisp’s finding in detail. Crisp and his team inferred that HGT between primates did not happen in the most recent common ancestor of all primates, but way back when our common ancestors were fish. Crisp also identified some genes as emerging from fungi!


We have genes from mushrooms……


What does this mean for us humans? Are we going to start growing gills like fish, or decomposing dead matter like fungi? This second scientific paper looks at the implications of HGT in evolution. The author, Michael Syvanen, discusses how how the origin of animal cells could be a form of HGT, and that structural genes that are fundamental to everyday life were adapted from genes of prokaryotes.

Don’t worry, we won’t be growing gills anytime soon. That already happened thousands of years ago when we evolved into vertebrates!

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Three-Parent Babies

Last month, the United Kingdom voted to legalize “three-parent babies.” They are the first country to allow this procedure and within a year, the first of these babies will be born.


Mitchondrial replacement can prevent mitchondrial disease from being passed on to future generations
Photo courtesy of Flickr

These babies will have three parents in an attempt to eradicate mitochondrial disease. In short, this disease is caused by mutations in the mitochondrial DNA which in turn leads to insufficient energy for the cell’s survival. The death of cells causes the organs to fail ultimately leading to death. This illness is passed through the mother to her children. There are three traditional choices for mothers with this disease that hope to have children. They can adopt a child, use a donor egg, or become pregnant and at 11 weeks have the fetus tested for mitochondrial disease. At that point, they can choose to terminate the pregnancy. However, there is new hope on the horizon for prospective mothers in the United Kingdom that have this disease. The government recently legalized a method of three-person in-vitro fertilization, mitochondrial donation.


There are two methods of mitochondrial DNA replacment, maternal spindle transfer and pronuclear transfer.
Photo courtesy of Flickr

There are two different methods of mitochondrial donation. The first is named maternal spindle transfer where the repair is completed before fertilization. An egg is taken from both the mother and the donor and both the nuclei are removed. Next, the mother’s nucleus is kept and inserted into the donor’s egg while the donor’s nucleus is destroyed. Then, the donor egg containing the mothers nucleus and healthy mitochondria is fertilized with the father’s sperm. Finally, the egg is implanted back into the mother.

The other method of fertilization is named pronuclear transfer. In this procedure, the repair is done after fertilization. First, an egg is taken from both the mother and the donor. Then, they are fertilized with the father’s sperm. Before the eggs have a chance to replicate, the chromosomes from each egg are taken out. Next, the donor ones are thrown out and the donor egg is filled with the mother’s chromosomes. Finally, the egg is implanted in the mother.

There are many ethical concerns attached to this issue causing countries including Canada to hold back on legalizing this procedure. In Canada, this specifically has to do with the fear of opening the doors to designer babies. Not only are designer babies horrifically dystopian and Brave New World-esque, it may also decrease the natural variability of the human race, something that is required for the race to survive and adapt. However, changing a baby’s mitochondrial DNA is a far cry from creating designer babies. The procedure has no effect on their hair or eye colour and it isn’t enhancing them in any way. In fact, the change affects less than 1% of the baby’s total genome.

Other ethical concerns include “germline” genetic engineering, the fact that one of the embryos are destroyed in the pronuclear transfer and that we are unsure of this procedure’s effects on humans. Even with these concerns, this procedure is worth it if we can eradicate a painful disease affecting millions.

Check out this video by Elliot M. that sums up mitochondrial replacement:

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– Siana Lai


Life in a Petri Dish: From Skin Cells to Fertility

The number of partners facing infertility in Canada has doubled since the 1980s; it is now predicted that every one in six couples face infertility. With the numbers rising, due to factors such as obesity and substance use, this issue is becoming increasingly more common in our modern world and scientists across the globe are in a constant race to overcome it.

New research emerging from Cambridge University has provided hope in the form of a new infertility treatment. In collaboration with the Weizmann Institute of Israel, researchers have come forward with a potential new form of in-vitro fertilization. Its origin? Human adult skin cells.

IVF: the insertion of sperm into a human oocyte (egg cell).

IVF: The insertion of sperm with a glass pipette into a human oocyte (egg cell). In-vitro Source: Wikimedia Commons

For the first time, scientists have been able create manmade (reproductive) primordial germ cells, known as PGCs; these cells act as predecessors and are considered the common origin of  both sperm and egg cells. PGCs arise from pre-existing adult stem cells, which is an undifferentiated cell that has the ability to develop into many different tissue types. Their ancestor-like quality that creates a common origin, allows the eventual creation of  many different cell types, such as skin and liver cells.

Kyoto University used skin cells to create mice pups in 2012.  Lab Mouse Source: Google

Kyoto University used skin cells to create mice pups in 2012.
Lab Mouse Source: Wikimedia Commons

The team of researchers, led by Hanna and Azim Surani, followed a “recipe” originating from a Stem Cell Lab at Kyoto University, who created mice pups from a female germ cell by re-programming stem cells back in 2012. Based on this, the Cambridge-Weizmann team replicated the in-vitro portion of the experiment, where they grew the cells in a sterile and controlled environment.

The team was successful in making the primordial reproductive cells from human stem cells. The key finding was a gene known as SOX17, who is responsible for directing stem cells into their specialization; this is how primordial germ cells are created. This gene can also direct stem cells into becoming the external layer of skin, therefore showing that the reprogramming of an adult tissue type, such as skin cells, could give rise to the primordial germ cells.

Current British law has banned any fertility clinics in the United Kingdom from using a manmade sperm and eggs to treat an infertile couple, due to both ethical reasons as well as safety concerns. If this law is changed, the creation of a genetically identical sperm or egg cell can be taken from a patient for use in in-vitro fertilization.

Mother and Child Source: Wikimedia Commons

Mother and Child
Mother Source: Wikimedia Commons

This discovery has laid down foundation for all future research; scientists can now compare the development of both sperm and egg cells in both healthy as well as infertile people. Representing a huge step forward in the world of stem cell biology, the researcher’s work, published in the journal Cell, may mean a change in the age at which a woman can stop having children. This breakthrough means that manmade primordial germ cells are capable of passing on an offspring’s genetic code to their own offspring, creating the fundamental bond from generation to generation.

Check out Cambridge University’s video on a similar topic, the derivation of brain cells from skin cells:

Thanks for reading!

Samantha Mee