Dr Kamil Jaron is a new Group Leader in the Tree of Life programme at the Sanger Institute. He is interested in strange reproduction (in a genomic sense). His new group’s research will explore the changes in DNA variation and chromosome structure caused by the different ways species reproduce, and see how that drives evolution. We talked to Kamil about how he hopes to answer some fundamental evolutionary questions and why some of the answers could lie in the testes of tiny flies.
Why strange reproduction?
I think partly this concept of ‘strange’ reproduction fits my personality. Not necessarily that I always want to go against the stream, but that I am drawn to doing so. I often find in science that the counterarguments are dismissed too soon. So I start asking those questions, and sometimes I never stop.
I started out by studying asexual reproduction for my PhD. This is the most extreme way organisms inherit DNA, simply by cloning themselves in some way. But afterwards I decided that I wanted to look at other forms of reproduction that are strange for different reasons.
So, I went to work with Laura Ross at the University of Edinburgh. Here we looked at species where the males - although still diploid, with pairs of chromosomes like us - only passed on the genetic information inherited from their mum to the next generation.
Why strange reproduction?
I think partly this concept of ‘strange’ reproduction fits my personality. Not necessarily that I always want to go against the stream, but that I am drawn to doing so. I often find in science that the counterarguments are dismissed too soon. So I start asking those questions, and sometimes I never stop.
I started out by studying asexual reproduction for my PhD. This is the most extreme way organisms inherit DNA, simply by cloning themselves in some way. But afterwards I decided that I wanted to look at other forms of reproduction that are strange for different reasons.
So, I went to work with Laura Ross at the University of Edinburgh. Here we looked at species where the males - although still diploid, with pairs of chromosomes like us - only passed on the genetic information inherited from their mum to the next generation.
“The more I looked, the more I realised how strange and weird genomes can be - and actually how much about genomes is unknown.”
That is kind of weird, it doesn’t really make much sense. But thousands and thousands of species on the tree of life do this. For example, the transition from another form of reproduction to this version has happened at least seven times in various groups of arthropods.
And so the more I looked, the more I realised how strange and weird genomes can be - and actually how much about genomes is unknown. We have tended to focus on species for which the genomes are easy to sequence or process. But what about things with really big genomes? Or organisms that are really, really tiny or hard to rear?
I kept digging and found so much weirdness in the genomes. And then I began to see lots of constraints in how we deal with the genomic data. So I started developing methods and tools to analyse this.
Fungus gnats have two large chromosomes that are found only in their sperm and egg cells. These germ-line restricted chromosomes are not found in any other part of the gnats' bodies. Image credit: Andy Murray (https://www.flickr.com/people/89396233@N00), CC BY-SA 2.0
Mealybugs employ paternal genome elimination in their reproduction, but with an additional quirk. Some male genes (found on the B chromosomes) are bundled in with the chromosomes inherited from the bug's mother and passed on to the next generation. Image credit: Carl Davies, CSIRO (https://www.scienceimage.csiro.au/image/3590), CC BY 3.0
Animals with strange reproduction across the Tree of Life: human louse, ant, fungus gnat, bee, mealybug
That is kind of weird, it doesn’t really make much sense. But thousands and thousands of species on the tree of life do this. For example, the transition from another form of reproduction to this version has happened at least seven times in various groups of arthropods.
“The more I looked, the more I realised how strange and weird genomes can be - and actually how much about genomes is unknown.”
Dr Kamil Jaron
And so the more I looked, the more I realised how strange and weird genomes can be - and actually how much about genomes is unknown. We have tended to focus on species for which the genomes are easy to sequence or process. But what about things with really big genomes? Or organisms that are really, really tiny or hard to rear?
I kept digging and found so much weirdness in the genomes. And then I began to see lots of constraints in how we deal with the genomic data. So I started developing methods and tools to analyse this.
Fungus gnats have two large chromosomes that are found only in their sperm and egg cells. These germ-line restricted chromosomes are not found in any other part of the gnats' bodies. Image credit: Andy Murray (https://www.flickr.com/people/89396233@N00), CC BY-SA 2.0
Mealybugs employ paternal genome elimination in their reproduction, but with an additional quirk. Some male genes (found on the B chromosomes) are bundled in with the chromosomes inherited from the bug's mother and passed on to the next generation. Image credit: Carl Davies, CSIRO (https://www.scienceimage.csiro.au/image/3590), CC BY 3.0
Animals with strange reproduction across the Tree of Life: human louse, ant, fungus gnat, bee, mealybug
Scaling up at Sanger
I believe we need to study evolutionary patterns on a large scale. I’m certainly not the first person to study reproduction. So how come we still don’t have a satisfactory explanation for the diversity of reproduction out there? Why are these questions still questions?
I think it is because studies until now have focused on individual instances in evolution, and that is vastly affected by the random way genomes evolve. So it’s hard to tell if something interesting is only specific to a certain lineage, or whether it is somehow a consequence of this strange reproduction.
The Tree of Life programme’s main focus is generating reference genomes for all eukaryotic species - every plant, animal, fungus and protist. What I want to do at Sanger is create a way to also sample the karyotypic diversity across all these eukaryotes. That means looking at the complete set of chromosomes and seeing how that changes between individuals within the same species.
“I believe we need to study evolutionary patterns on a large scale... Until now [studies] have focused on individual instances in evolution, and that is vastly affected by the random way genomes evolve.”
The Sanger Institute's DNA sequencing in action
Scaling up at Sanger
I believe we need to study evolutionary patterns on a large scale. I’m certainly not the first person to study reproduction. So how come we still don’t have a satisfactory explanation for the diversity of reproduction out there? Why are these questions still questions?
“I believe we need to study evolutionary patterns on a large scale... Until now [studies] have focused on individual instances in evolution, and that is vastly affected by the random way genomes evolve.”
Dr Kamil Jaron
I think it is because studies until now have focused on individual instances in evolution, and that is vastly affected by the random way genomes evolve. So it’s hard to tell if something interesting is only specific to a certain lineage, or whether it is somehow a consequence of this strange reproduction.
The Tree of Life programme’s main focus is generating reference genomes for all eukaryotic species - every plant, animal, fungus and protist. What I want to do at Sanger is create a way to also sample the karyotypic diversity across all these eukaryotes. That means looking at the complete set of chromosomes and seeing how that changes between individuals within the same species.
The Sanger Institute's DNA sequencing in action
Springtails and fly testes
I recently got interested in the chromosomes found in certain families of flies, called the germline restricted chromosomes. As the name suggests, these chromosomes are only found in the sex cells, and they get eliminated in all the other (somatic) cells.
It’s a bizarre phenomenon. But if we want to capture and understand it, we have to sequence fly testes. Mark Blaxter, who heads Tree of Life at Sanger, already has protocols for sequencing the DNA of single nematodes, which are tiny worms. So if we can sequence a single nematode, we can sequence a single pair of fly testes. And if we succeed in doing so, we can finally start asking questions about what the germ-line specific DNA actually does, or where it comes from.
“If we can sequence a single pair of fly testes, we can start asking questions about what germ-line specific DNA actually does, or where it comes from.”
“The other tiny organisms which fascinate me are springtails... I hope that [they] will provide insights into very fundamental evolutionary questions.”
The other tiny organisms which fascinate me are springtails. If you look closely, you can see them jumping about in damp soil. I have already been out in the Wellcome Genome Campus grounds collecting several local species.
I hope that studying springtails will provide insights into very fundamental evolutionary questions. In particular, we often discuss how the evolution of X chromosomes is different from other chromosomes. There are several explanations for that, which we are still struggling to understand and disentangle.
Enter the springtails, which have two really large X chromosomes, but also reproduce via paternal genome elimination, which I mentioned before. That means that, unlike in other organisms, the transition patterns of X chromosomes and all the other chromosomes - the autosomes - are now the same. Springtails will allow us to compare the X chromosomes and the autosomes while eliminating all the other effects getting in the way.
Kamil Jaron collecting globular springtails on the Wellcome Genome Campus, and globular springtails in close up
Springtails and fly testes
I recently got interested in the chromosomes found in certain families of flies, called the germline restricted chromosomes. As the name suggests, these chromosomes are only found in the sex cells, and they get eliminated in all the other (somatic) cells.
It’s a bizarre phenomenon. But if we want to capture and understand it, we have to sequence fly testes. Mark Blaxter, who heads Tree of Life at Sanger, already has protocols for sequencing the DNA of single nematodes, which are tiny worms. So if we can sequence a single nematode, we can sequence a single pair of fly testes. And if we succeed in doing so, we can finally start asking questions about what the germ-line specific DNA actually does, or where it comes from.
“If we can sequence a single pair of fly testes, we can start asking questions about what germ-line specific DNA actually does, or where it comes from.”
Dr Kamil Jaron
The other tiny organisms which fascinate me are springtails. If you look closely, you can see them jumping about in damp soil. I have already been out in the Wellcome Genome Campus grounds collecting several local species.
I hope that studying springtails will provide insights into very fundamental evolutionary questions. In particular, we often discuss how the evolution of X chromosomes is different from other chromosomes. There are several explanations for that, which we are still struggling to understand and disentangle.
“I hope that studying springtails will provide insights into very fundamental evolutionary questions.”
Dr Kamil Jaron
Enter the springtails, which have two really large X chromosomes, but also reproduce via paternal genome elimination, which I mentioned before. That means that, unlike in other organisms, the transition patterns of X chromosomes and all the other chromosomes - the autosomes - are now the same. Springtails will allow us to compare the X chromosomes and the autosomes while eliminating all the other effects getting in the way.
Kamil Jaron collecting globular springtails on the Wellcome Genome Campus, and globular springtails in close up
A new team with big questions
I am an evolutionary biologist at my core. So I don’t see myself as trying to create, for example, some applied solutions for things in agriculture. Perhaps people will use my research to do so, but that’s not why I am doing it.
I feel my research is tackling very fundamental evolutionary biology. We’re always talking about selection and linkage and about dominance, and how these all somehow affect evolution. But it’s hard to disentangle.
Joining Sanger has given me the opportunity to recruit a team of scientists to attempt this. The team is new, and I am looking forward to seeing how we all work together. I quite appreciate people being different. Some people act like diversity is just a buzzword, and I dislike that. Why would I hire somebody who is thinking the exact same thing as me, what do I gain?
I’m also a very frank person. I grew up in the Czech Republic - we don’t ask how are you unless we expect to hear an answer. But I’m a very goofy person. That maybe sounds a bit weird, but it kind of works for me. I’m mildly terrified to manage a team with this attitude, but I’m really excited about it too!
“My research is tackling very fundamental evolutionary biology... But it’s hard to disentangle... Joining Sanger has given me the opportunity to recruit a team of scientists to attempt this.”
“Our aim is to democratise this whole field... to revolutionise the way we analyse sex chromosomes.”
Our ultimate aim is to democratise this whole scientific field. Right now most labs are spending much of their time just trying to get their favourite sex chromosomes sequenced. We want to create a standard that would normalise this and remove that barrier for everyone. We hope to revolutionise the way we analyse sex chromosomes.
This information will not only allow clinicians to better diagnose and understand disease and its effects, but also enable scientists to design and produce new proteins and small molecules for disease treatment and bioengineering.
A new team with big questions
I am an evolutionary biologist at my core. So I don’t see myself as trying to create, for example, some applied solutions for things in agriculture. Perhaps people will use my research to do so, but that’s not why I am doing it.
I feel my research is tackling very fundamental evolutionary biology. We’re always talking about selection and linkage and about dominance, and how these all somehow affect evolution. But it’s hard to disentangle.
“My research is tackling very fundamental evolutionary biology... But it’s hard to disentangle... Joining Sanger has given me the opportunity to recruit a team of scientists to attempt this.”
Dr Kamil Jaron
Joining Sanger has given me the opportunity to recruit a team of scientists to attempt this. The team is new, and I am looking forward to seeing how we all work together. I quite appreciate people being different. Some people act like diversity is just a buzzword, and I dislike that. Why would I hire somebody who is thinking the exact same thing as me, what do I gain?
I’m also a very frank person. I grew up in the Czech Republic - we don’t ask how are you unless we expect to hear an answer. But I’m a very goofy person. That maybe sounds a bit weird, but it kind of works for me. I’m mildly terrified to manage a team with this attitude, but I’m really excited about it too!
“Our ultimate aim is to democratise this whole scientific field... to revolutionise the way we analyse sex chromosomes.”
Dr Kamil Jaron
Our ultimate aim is to democratise this whole scientific field. Right now most labs are spending much of their time just trying to get their favourite sex chromosomes sequenced. We want to create a standard that would normalise this and remove that barrier for everyone. We hope to revolutionise the way we analyse sex chromosomes.
This information will not only allow clinicians to better diagnose and understand disease and its effects, but also enable scientists to design and produce new proteins and small molecules for disease treatment and bioengineering.
