• 6 months ago
Vous êtes-vous déjà demandé comment quelque chose d'aussi innocent que l'eau pourrait causer des ravages sur votre ADN ? Eh bien, attachez vos ceintures car nous plongeons dans la science qui se cache derrière. Que ce soit à cause des radiations UV, des produits chimiques, ou simplement de l'usure, l'eau peut causer des changements minuscules mais significatifs à la structure de notre code génétique. Joignez-vous à nous alors que nous démêlons les mystères des dommages à l'ADN causés par l'eau et explorons le monde fascinant de la biologie moléculaire. Alors, prenez votre blouse de laboratoire et une tasse d'eau (peut-être pas en même temps), et découvrons les effets secondaires pas si sympathiques de l'H2O sur notre ADN. Animation créée par Sympa.
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Fun
Transcript
00:00 You probably won't be surprised to learn that the water coming out of your sewage
00:04 doesn't just come from a nearby river.
00:07 In most cases, it has to go through a long process before being made drinkable
00:12 or used to take a shower.
00:14 But a part of the scientific community is concerned by the way we treat this water
00:20 before it is clean enough for human consumption.
00:23 The problem is that some countries still use substances in the treatment of their water
00:28 that could harm our DNA.
00:30 It seems that the culprit is colloidal silver.
00:33 It is a mineral that has been used in medicine for a long time
00:36 because it can eliminate some germs.
00:38 However, it can do more harm than good.
00:41 In addition, there is little evidence that it actually works to disinfect water.
00:45 And now, researchers warn us that there is a risk that it can actually damage DNA.
00:51 Researchers have compiled previous studies where the effects of silver,
00:55 silver nitrate and silver nanoparticles had been measured.
00:59 And, although none of these studies draw a definitive conclusion,
01:03 we think there is a chance that silver-treated water is harmful.
01:07 Currently, official directives on the quality of drinking water
01:11 do not include any precise value for the presence of silver,
01:14 but they suggest that a very low concentration could be tolerated
01:18 without presenting health risks.
01:20 In summary, we need more advanced research to determine
01:25 whether silver-treated water has any other allergens present in your altered DNA.
01:29 In the meantime, we may need to look at other ways of treating silver,
01:34 just to be sure.
01:36 Wait a minute, what is DNA first?
01:39 I would also ask myself the same question if I were you.
01:42 Let's talk a little about the nucleus of molecular biology,
01:45 the desoxyribonucleic acid, or, as we like to use simpler acronyms, DNA.
01:51 You may have heard that it was the cornerstone of all life, and it's quite true.
01:56 DNA is the ultimate instruction manual for all living beings,
02:00 from the smallest microbe to the biggest elephant, you and me included.
02:04 But DNA is much more than a simple set of instructions.
02:07 It is the very definition of a family heritage,
02:10 passed down from generation to generation, like your grandfather's old watch.
02:15 And just like this watch, DNA has existed for a long time.
02:19 It dates back to the first forms of life that appeared on Earth.
02:22 Now, let's tackle what makes DNA so complex.
02:26 It is made up of small elements that are imbued, like pieces of a puzzle.
02:30 And when these pieces are arranged in a specific order,
02:34 they can order a little bit of everything, from the color of your eyes to the size of your feet.
02:39 Oh, you do it slow for us again, Ella.
02:41 But how does it all work?
02:43 How do we get the slightest information from these tiny pieces of a puzzle?
02:47 Well, it's a mystery that scientists have been working on for decades.
02:51 But one thing we know is that DNA has, so to speak, the spirit of a team.
02:57 Each cell in a multicellular organism has a complete set of DNA.
03:01 What's interesting is that, in general,
03:04 our precious genetic code strands can take a lot of damage.
03:08 A single cell can suffer up to 10,000 road accidents within its chromosomes in just 24 hours.
03:15 But don't worry, most of these little incidents are fixed,
03:19 like with a good band-aid.
03:21 However, some damage can lead to permanent errors,
03:25 also called genetic mutations or restructuring,
03:29 which can lead to unenviable affections in the human body.
03:32 In fact, some studies suggest that DNA could be damaged by some of the most surprising factors,
03:38 like salt, for example.
03:40 It would seem that if we were technically able to sprinkle salt on DNA,
03:44 it could cause serious damage to it.
03:46 But don't worry too much, there's a light at the end of the tunnel.
03:50 As soon as the salt level drops, these damages begin to heal.
03:54 The only problem is that scientists don't know exactly where these accidents occur,
03:59 nor what their nature is.
04:01 And speaking of a salty environment,
04:03 there is a tiny microbe called Allobacterium,
04:07 which lives in the Dead Sea and could teach us a lot about biotechnology
04:11 and even about life on other planets.
04:13 It's because this little creature is a real prodigy.
04:16 Allobacterium could actually hold the key,
04:19 allowing to protect astronauts from one of the biggest threats
04:23 that would weigh on them during a mission on Mars, cosmic radiation.
04:27 It could be dangerous for astronauts' DNA and could potentially cause serious diseases.
04:32 But Allobacterium seems to be a master of the art of damaged DNA repair.
04:37 And scientists want to learn from him.
04:40 Researchers at the University of Maryland have conducted a series of experiments
04:43 to test the limits of Allobacterium's self-repairing capabilities
04:47 using cutting-edge genetic techniques.
04:50 Even after seeing their DNA completely fragmented,
04:53 these tiny organisms are able to reconstruct the entirety of their chromosomes
04:57 and make it viable again in just a few hours.
05:00 But how did Allobacterium become such a tenacious survivor?
05:05 Well, it naturally thrives in rather inhospitable places,
05:09 such as the saltiest water streams, such as the Dead Sea.
05:13 In this region, most marine organisms would quickly dry up
05:17 and not survive for long.
05:19 But Allobacterium has evolved to adapt to this lifestyle.
05:22 And this could explain why it is so gifted at surviving radiation
05:26 and other types of aggression.
05:28 During an experiment, researchers exposed Allobacterium cells
05:32 to intense UV radiation,
05:34 which completely destroyed most of the other microbes.
05:37 Yet, 80% of Allobacterium cells survived
05:41 and continued to live and reproduce properly.
05:45 In this other experiment, we used an empty cell to expose
05:49 the cellulose Allobacterium, a disconditioned semblables
05:53 a cellulose d'Ellespace.
05:55 And these tiny cells were trapped inside salt crystals,
05:59 which then protected them from any additional damage.
06:03 Some scientists even claim to have discovered living Allobacterium cells,
06:07 imprisoned in old salt deposits, 250 million years old.
06:11 If this is true, it could have profound implications
06:15 for microbial life on Mars,
06:17 given the data collected by the Rovers Spirit and Opportunity,
06:21 which suggest that the Martian surface used to contain
06:25 saltwater basins.
06:27 We can see things this way.
06:29 Of course, salt and especially saltwater can damage the DNA.
06:33 But they can also help us better understand how
06:37 we can survive in extreme environments.
06:40 There are still many things we do not understand about human DNA, of course.
06:44 But did you know that you and I share no less than 90.99% of our DNA?
06:49 We are almost genetic twins, consider this.
06:52 You could have a devastating smile or a opulent hair,
06:56 while I could have the most jovial faux-sets,
06:59 or the gift of reciting each line of my favorite series.
07:02 It's very good.
07:03 But at the end of the day, we are all made of the same building blocks.
07:07 It is this 0.01% of DNA that distinguishes us and makes life interesting.
07:12 It could also be that we have more in common with cabbage than we would like to believe.
07:16 It turns out that 50% of our DNA is identical to that of this vegetable.
07:21 But do not worry, it is not as if it were going to start growing leaves or whatever.
07:26 It is fascinating to consider that each living being on Earth
07:30 evolved from the same ancestor more than 4 billion years ago.
07:34 And this ancestor was probably just a tiny unicellular organism
07:39 with a tiny bit of DNA.
07:42 From there, it evolved into everything that exists,
07:45 bacteria to humans, with their billions of cells.
07:48 What about our closest relatives in the animal kingdom?
07:51 Well, this distinction comes back to chimpanzees and bonobos.
07:55 Recent studies have shown that bonobos shared as much of our DNA as their chimpanzee counterparts.
08:01 But here's the thing, although sharing about 99% of our DNA with these primates,
08:07 we humans are very different from them.
08:10 Well, some of us are.
08:12 Researchers who have sequenced the bonobo genome have discovered some intriguing differences in the DNA of the three species.
08:19 This could be the key to understanding why these incredible primates do not look and behave like us,
08:26 even though they are so close in age.
08:28 Finally, for my part, I have a little cousin who acts more or less like them.

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