Briefing Chat: Stressed mitochondria spawn new 'organelles' in cells

Introduction

0:00a cast powers the world's best podcasts here's a show that we recommend in uptown new york city underdogs created a sound that changed music forever and we called it salsa and one label captured that sound like no other bonnie records i'm rosie perez and this is our thing the birth of salsa in nueva york

0:31an original podcast from futuro studios premiering may 26th follow wherever you get your podcasts a cast helps creators launch grow and monetize their podcasts everywhere a cast.com

Mitochondria Story

0:51hi benjamin here welcome to the nature briefing podcast the friday show where we talk about a couple of stories we've read about in the nature briefing which is of course nature's daily email roundup of the latest science stories and joining me today to chat is none other than sharmini bundell sharmini thank you for being here i am actually really excited about today's story why don't we start with you then in that case tell me what you've got look i'll give you the preview it's got mitochondria we all love mitochondria ding it's got parasites ding ding it's got evolution i love

1:25evolution ding ding ding ding ding this is a pre-print from bioarchive so not a peer-reviewed paper but i read an article in nature where they've covered it and yes it's about mitochondria the powerhouse of the cell little organelles found in eukaryotic cells producing energy and it's kind of about how our cells got to be how they are right but it came from an experiment with a parasite okay parasite biology often very strange tell me what's going on here so a group of researchers infected

1:56human cancer cells with a parasite called toxoplasma gondii this is the parasite that causes toxoplasmosis which if you've ever gotten pregnant they tell you to stay away from cat poo so you don't get toxoplasmosis right but it's actually a really common parasite and it's also here's a little side tour it's the one that changes the behavior of rodents to make them more likely to get eaten by cats they stop being scared yeah that's a whole nother story but go look it up it's great mind-controlling parasite so anyway these researchers are there infecting these human cancer cells

2:30with some toxoplasma and what happened was that these little parasites in the cell started having an effect on the mitochondria in the cell these membrane bound organelles and these mitochondria started to shed their outer membranes and that membrane then formed its own little bubbly structure they call them spots structures positive for outer mitochondrial membrane spots oh and those little spots went and engulfed some other little organelles little things in the cells called lysosomes which

3:02do sort of waste disposal jobs in the cell and it turns out that this weird change was actually helpful to the parasite when they stopped this from happening the parasite didn't do as well so something about this process that's triggered by the parasite is benefiting the parasite so let me get this straight so parasite infects cell yes something that you would expect is a defense mechanism isn't so the mitochondria loses its membrane that joins with another organelle but instead of defeating a parasite

3:33this helps the parasite yeah you make an interesting point because quite possibly this kind of reaction from the mitochondria this ability to shed some of their membranes and form new organelles that could well be usually a benefit that could be an adaptation to maybe help the cell adapt to different stresses by creating new structures that is possible but yes certainly in this one specific case which is a very narrow thing that they were looking at this one particular situation but yeah in this situation the

4:04toxoplasma gondii is definitely doing well from this and the implication here is that this is an adaptation by this parasite to benefit it by manipulating these mitochondria and also you mentioned that this is a new organelle and that's super interesting too well so here is where it gets much broader we're gonna step away from infecting cancer cells with a specific parasite and we're gonna start asking questions about how our cells evolved okay so you might know that the prevailing theory is that

4:39back in the mists of time there were two different types of cell and one of the bigger types absorbed one of the little smaller bacterial types and instead of eating it dissolving it consuming it kept it around and that is the origin we think of what's called eukaryotic cells the complex cells in animals and plants that have organelles in so the idea is we got organelles by essentially eating a bacteria and keeping it mitochondria have their own little dna in them and it's not the same as the nuclear dna it's

5:15kind of like bacterial dna right so mitochondria are thought to originally have been a bacterial so our pro carry on but other organelles then are they thought to have come from somewhere else as well well there's a kind of big gap in our understanding of eukaryotic cells because there's loads of differences between us and the ancestors that would have been maybe absorbing little bacteria and turning them into mitochondria you know we have nuclear membrane we have other organelles as well and i don't think it's super clear where they all came from but this observation that the mitochondria

5:48can in some circumstances shed some outer membrane and kind of make new organelles that's really fascinating because that could be a possible route for making other organelles this is a very new idea but the suggestion here is that it could well be that other organelles came from mitochondria that them shedding their membranes made some of the other organelles we find in ourselves oh so that's the evolution aspect that you mentioned then obviously it's hard to know exactly what went on what happens

6:21now this is an unusual finding like where do researchers take it yeah and it supports a particular theory ideas that have been shared about how eukaryotic cells and their organelles might have developed it's one little clue it maybe backs up an older paper that people were really skeptical of that maybe suggested the same thing but now they might go and we look at that and think oh yeah maybe there was something in that and maybe spur some new avenues of investigation but i just think it's really interesting that such a niche look at the behavior of this strange little parasite could give us

6:54this potential clue to this grand evolutionary question well that is a fascinating one and a

Giant Octopus

7:00strange finding that potentially opens up some broader questions but let's move on to our second story today that also i guess opens up some questions but i think we need to hop into our absolutely real time machine for this we need to head back to the late cretaceous period like from about 100 to about 70 million years ago i'd love a bit of late cretaceous yeah well we're going to meet an extinct creature that was potentially absolutely enormous and a top underwater predator now this is a story that i read

7:31in nature and it's based on a paper in science oh underwater i was going to say oh is it dinosaurs i love dinosaurs but underwater so i guess not there were some marine reptiles swimming around i reckon cretaceous times mosasaurs ichthyosaurs maybe is that where we're going with this absolutely right that is the right sort of time so mosasaurs yes giant aquatic reptiles like 12 meters long yeah it's about 40 feet long plesiosaurs i know you and i have spoken about plesiosaurs with their long neck many times yeah and that's in the ocean and on land of course we've got t-rex that sort of time so this was a

8:03period of giant vertebrates right these are big old animals and it's often thought that invertebrates were kind of like basically dinner essentially for the other animals quite small things but there may have been an animal that out stripped all these vertebrates it was an invertebrate an octopus in fact and an absolutely gargantuan one but octopuses i mean octopuses can grow quite big today but we're not talking shark size well maybe we are so let me give you some facts so you're right

8:35cephalopods more generally so that includes octopuses can get quite big right the giant squid can be like 10 meters long but this octopus is thought to be well about the length of a tennis court so 19 meters long like 60 feet long so it would have potentially massively outstripped the mosasaurs and things like that now these animals have been identified from chitinous jaw fossils right so octopuses have got kind of a beak that's made out of chitin and it's the only bit that survives the

9:07fossilization period really because soft-bodied animals don't preserve very well it's very unusual to find a soft-bodied animal so not much has been known about the size of these octopuses and their lifestyle and so forth and that's what this new work has tried to maybe open the door on a little bit so are they essentially just guessing from the beaks because the beak is all we have everything else is an extrapolation pretty much that's exactly right so the team re-analysed 15 large fossil octopus jaws and they found 12 new fossils as well by looking at some

9:42carbonate rocks and they worked with ai here to try and find these things and they divided these animals into two species now apparently these belong to the same evolutionary group as modern dumbo octopuses you know these ones that have like the little ears and they flap along and they live quite deep that's right they're actually fins to help them swim to the water anyway on the basis of the anatomy of modern octopuses right they've had to do some comparisons they reckon that one of the species nanomotithis haegartii or hageti i hope i'm pronouncing that correctly could have been

10:15say 19 meters long potentially although a lot of that would have been its arms right the head part would potentially only have been a mere four meters long only four meters right yeah i'm imagining that i feel like this is ripe territory for a horror movie of some kind with a terrifying giant cretaceous octopus in yeah well of course the kraken that mythological cephalopod that terrified sailors for centuries right that was potentially based on giant squids which as i say

10:45about 10 meters long this one is twice as long as that but not everyone i have to say is convinced a lot of this work as we've said is based on extrapolating and looking at modern octopus species and there is a lot of variability in modern octopuses between the sort of head bit i suppose and the arm length right some folk are saying that maybe this octopus would have been at the lower end of the team's estimates putting it around just six and a half meters long pretty small it's kind of hard to know but

11:17the team have also made some other inferences as well about the lives of these massive creatures did they eat mosasaurs for breakfast maybe not mosasaurs but these beaks were pretty chipped and they showed signs of wear now the biggest one of these animals they reckon that maybe 10 of the jaw had been worn down maybe by crushing things like crustaceans and you know bivalves smaller hard

11:49prey which could chip this jaw and the authors reckon that the pattern of wear suggests that these animals were essentially apex predators in the ocean during the cretaceous period and what's kind of weird is that there's an asymmetric wear pattern so one side was maybe more worn down than the other and the authors reckon that this shows that these animals had a preference for kind of how they ate which suggests that maybe they were capable of complex behavior if they favored one side over the other

12:20suggesting that maybe these animals were pretty smart now we know that modern octopuses are very intelligent animals we've covered that on the podcast a lot but folk are cautious to kind of give these extinct animals an entire backstory based on one bit of them it's hard to find out unless we use our obviously very real time machine yeah Germany but i guess this work does give us a little window into a lost past like there's so little that remains of these extinct soft-bodied animals and

12:52i guess hard to get a sense of what they were really like fine stomach contents this sort of thing but i do think these animals are absolutely fascinating these giant cephalopods like whenever we see a video of i'm like right must watch that right now i want to see what it's all about yeah you know it's amazing how information from sometimes just such faint markings on a rock and i love how it brings to life in my imagination this kraken-like intelligent giant octopus i love that agreed a wonderful story and we'll put a link to it in the show notes along with a link to the story you've talked about today

13:26shamni listeners i think that's probably all we've got time for this week if you'd like to sign up to the nature briefing to get even more stories like this delivered directly to your inbox then look out for a link in the show notes otherwise all that remains to be said is shamni bundell thank you as always for being with me today thanks very much and thanks for listening everyone we'll see you next time big monthly car insurance bills are hard on your budget but not with hugo hugo breaks up your insurance bill into tiny pieces so you can pay a little bit at a time get a quote today and start

14:00driving insured with just seven days of coverage after that pay at your own pace like every week or even a day at a time hugo is car insurance that fits your budget stress-free get your car insured today at with hugo dot com that's with hugo dot com a cast powers the world's best podcasts here's the show that we recommend in uptown new york city underdogs created a sound that changed music forever and we called it salsa

14:36and one label captured that sound like no other bonnie records i'm rosie perez and this is our thing the birth of salsa in nueva york an original podcast from futuro studios premiering may 26 follow wherever you get your podcasts a cast helps creators launch grow and monetize their podcasts everywhere a cast dot com you you you

15:07you