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Silver Mirror
Грех предаваться унынью, когда есть другие грехи!(c)
Завтра иду в Science Museum на воркшоп про будущее производства еды. После вычитки детенышевского диплома, когда ко мне пришла их рассылка, я не раздумывая записалась, потомоу что во-первых интересно, а во-вторых мне кажется в таких мероприятиях должно участвовать как можно больше разных людей, чтобы было учтено как можно больше разных точек зрения (это, кстати, не значит, что ко всем из них нужно прислушиваться при выборе следующих действий, но стоит принимать их во внимание, чтобы понять с чем придется столкнуться в плане реакции и подготовить контраргументы).

Так вот, в процессе подготовки к этому мероприятию, я тут наконец решила почитать про ГМО, точнее как именно их производят и в чем принципиальное отличие от тех же культур, которые получают методами селекции. В общем-то, главное отличие (помимо скорости получения культуры) в том, что там гены передаются не от растений того же вида или близких ему, а от других видов. Вот, например, интересная табличка:


(источник)

С другой стороны, в нашем геноме (равно как и в геномах других живых существ), масса материала, который фактически классифицируется как генетический мусор, то есть тот факт, что геномы существ разных видов перемешиваются, не является чем-то не встречающимся в природе: вирусы оставляли и оставляют свой след в геноме, а бактерии тоже меняются кусками генома, причем там аж три разных способа (могут сами между собой, могут с помощью вируса, а могут просто вбирать из окружающей среды). В New Scientist недавно на эту темы как раз была статья.



С третьей стороны, эта же самая статья говорит, что по сути наличие этого самого "генетического мусора" определяет (отчасти), какие куски нашего генома метилируются, то есть, какие гены "включаются/выключаются". Но это все только отчасти и очень многого мы пока просто не знаем, то есть отчасти наличие этого "мусора" влияет, отчасти нет, но насколько он влияет мы не знаем. Так вот, получается, что говорить о том, что генномодифицированные продукты это что-то, что противоречит природным механизмам, на мой лично взгляд, все-таки нельзя, потому что в природе это все тоже происходит и кстати никто не сказал, что всегда с позитивными результатами, так что по сути ничего нового не происходит - процесс идет чуть быстрее, но где гарантия что те же выведенные селекцией организмы не имеют в себе желанные признаки именно потому что их когда-то привнесла бактерия или вирус? Просто мы об этом не знаем и кажется, что это что-то принципиально отличающееся от ГМО.

В общем, завтра пойду, поучаствую и (главное-то) послушаю, что думают другие участники!

How our food is made may look very different in the near future. Agriculture and food industries are always changing, and the role of science and technology is becoming more and more important. Genetic modification, nanotechnology, robotics and automation are some of the emerging technologies adding to these changes. So what will the future of our food production look like and why?

Among the reasons why food production is always evolving are population growth and the changing environment. The United Nations’ Sustainable Development Goal for 2030 is working towards '...ending hunger, achieving food security and improved nutrition and promoting sustainable agriculture'. Will new technologies help, or make things worse?

Some technologies are so new that we aren’t sure about all of their likely impacts. This makes it difficult to decide which innovations to promote, and which to monitor very closely and potentially prohibit. We know that governments play a key role in promoting beneficial innovations on one hand, and regulating potentially harmful ones on the other. But who else is involved and what are the policy agendas of different groups?

In this interactive workshop we’ll explore the ways that science and technology are changing our food systems, and the contribution they can make to tackling challenges in food production.

You are junk: Why it’s not your genes that make you human
Genes make proteins make us – that was the received wisdom. But from big brains to opposable thumbs, some of our signature traits could come from elsewhere

By Colin Barras

IT WAS a discovery that threatened to overturn everything we thought about what makes us human. At the dawn of the new millennium, two rival teams were vying to be the first to sequence the human genome. Their findings, published in February 2001, made headlines around the world. Back-of-the-envelope calculations had suggested that to account for the sheer complexity of human biology, our genome should contain roughly 100,000 genes. The estimate was wildly off. Both groups put the actual figure at around 30,000. We now think it is even fewer – just 20,000 or so.

“It was a massive shock,” says geneticist John Mattick. “That number is tiny. It’s effectively the same as a microscopic worm that has just 1000 cells.”

We’ve only gradually come to grasp the full implications of this discovery. The blueprint for building a human, or indeed any complex creature, lies not only in our genes but in other, neglected parts of our genome. This long-overlooked DNA could have shaped iconic traits such as our upright stance, opposable thumbs, big brains, capacity for language, even our tendency to form monogamous relationships. We might like to think of ourselves as pinnacles of evolution, but actually we are mostly made of junk.

Not the whole story
In fact, one group was less surprised by the genome shock. Evolutionary biologists had long thought 100,000 genes would make for a fatally complicated genome. And we now know that genes – the sequences of DNA that code for proteins – account for just 1 or 2 per cent of our genome. For a long time the rest was considered to have no function at all, earning it the dismissive title “junk DNA”. While researchers still argue over how much of it truly is junk (see “What do you mean, junk?“), what’s clear is that this trash hides treasure – bits of DNA that control genes like a conductor directing an orchestra, switching them on and off at different times and in different cells.

These discoveries have come from studies comparing the human genome, junk and all, with those of chimps, mice and other animals. Some have even compared the genomes of Neanderthals and other extinct human species. The aim is to identify bits that look suspiciously different in modern humans, regions that are uniquely ours.

You need the whole genome for a complete picture of human traits
James Noonan at Yale University and Shyam Prabhakar at the Genome Institute of Singapore did this comparison across all mammals. They homed in on one piece of supposedly junk DNA called HACNS1, which has accumulated an unusually large number of mutations since we split from chimps. In other words, it was distinctly human.

Seeking clues to what HACNS1 does, they inserted it into the genomes of mouse embryos, along with a tiny, molecular label that would change colour whenever it was modifying the activity of surrounding genes. The label popped up in the embryos’ paws, in the area where digit 1 forms. In humans, that is either the thumb or big toe, suggesting that HACNS1 might influence their development.

For an idea of how, we can look at the fossil record. “Human thumbs and feet are among the most distinctive features of our species,” says Prabhakar. There is evidence that our ancestors evolved opposable thumbs about 3 million years ago, roughly when they began to use stone tools and only a few million years after we split from chimpanzees. It’s likely that early humans were also standing upright and were starting to walk on two legs around the same time or a little earlier. Doing so was tied to physical changes: toes shrank and foot arches became more rigid.

According to Prabhakar and Noonan, all this could have been happening around the time that HACNS1 began altering gene activity in our hands and feet. By subtly changing when and where genes were switched on, this little piece of DNA could have been modifying our hands and feet.

The study is not the only one to suggest that genetic controllers, rather than genes themselves, played a crucial part in shaping us. Gene activity is often regulated via methylation, a process in which a chemical unit called a methyl group is attached to a gene segment, influencing how much protein it produces. There are hints that junk DNA is involved.

In 2013, a study suggested that DNA methylation had helped our transition to walking on two legs, and perhaps our language skills too. Andrew Sharp of the Icahn School of Medicine at Mount Sinai, New York, and his colleagues compared DNA methylation patterns in humans, chimps, gorillas and orangutans, and found 171 genes with uniquely human patterns. A closer look suggested that these genes were involved in a handful of traits: regulating blood pressure, controlling the development of the inner ear and shaping facial muscles.

“What are the big differences between humans and chimps? We walk upright and we speak,” says Sharp. Walking upright lifted the brain, which meant our ancestors had to change how they regulated blood pressure to keep the brain supplied with enough oxygen. It also demanded exceptional balance, typically improved by modifying the inner ear. Speech, meanwhile, required an unprecedented level of control over the muscles in our face and around our mouth.

“Seeing these methylation changes in genes associated with these human traits, I just felt… wow, that’s incredible,” says Sharp.

A year later, David Gokhman and Liran Carmel at the Hebrew University of Jerusalem in Israel published a pioneering study of methylation in ancient DNA extracted from the fossils of extinct hominins. Using the fact that bits of DNA carrying methyl groups degrade differently from bits that don’t, the pair were able to reconstruct Neanderthal methylation patterns and compare them with human ones. They found key differences in genes that control limb development. “Our hypothesis was that these genes were less active in the archaic humans,” says Gokhman. That’s an exciting finding, because we know that Neanderthals typically had shorter, stouter legs than we do. So by switching some genes on or off, and making them pump out different amounts of proteins, methylation could have contributed to giving us longer legs than our extinct cousins.

“When our ancestors lost this piece of junk DNA, suddenly brain cells could proliferate“
The fact you can see these different methylation signals is tantalising, says Sharp. “It does suggest that they might have been involved in some major events in human evolution.”

Mattick, who is at the Garvan Institute of Medical Research in Sydney, Australia, thinks that junk DNA controls methylation. He suggests cells might transcribe junk into RNA, molecules typically associated with the process of making proteins (see diagram). But this “non-coding” RNA does something else: it influences when and where DNA methylation occurs.

That’s plausible, says geneticist and evolutionary biologist T. Ryan Gregory at the University of Guelph in Ontario, Canada, and he agrees that non-coding RNA might well be involved in managing methylation.

Carmel and Gokhman also found some unsettling patterns in their study. Some genes that are methylated differently in humans compared with Neanderthals appear to be linked to disease – including neurological and psychiatric disorders. “This suggests some kind of a link between our rapid brain evolution and the fact that many neurological disorders are more prevalent in humans, or even specific to humans,” says Gokhman.

A link between junk DNA and illness makes sense to Mattick. He likes to think of the genome as a set of organic building blocks. The proteins that genes code for are generic components that can be used to construct almost any animal. Encoded in our junk DNA is a set of instructions for how to assemble them to make one species or another. The problem with instruction manuals is that they can get damaged. And indeed, genetic diseases can often be traced to non-coding “junk” regions of the genome.

Emotional bonds
Just occasionally, damaging or even losing sections of this DNA creates a potent opportunity for useful innovation. For example, a team led by David Kingsley at Stanford University in California identified about 500 regions of our genome that are missing a chunk of genetic information which our primate relatives carry. They focused on two, both found in non-coding regions. One lies near a tumour suppressor gene, the other near a gene that makes a receptor for male hormones. They inserted chimp versions into mouse embryos and watched to see where they were most active. The answer turned out to be the brain and the groin.

The first chimp sequence controlled gene activity in a part of the brain where lots of new brains cells are born. Kingsley suspects that the chimp version exercises careful restraint over that process. When our ancestors lost this piece of DNA, he says, suddenly brain cells could proliferate at unprecedented rates and our brains got much bigger.

The junk that controls your genes
More speculatively, the second sequence might have changed our ancestors’ relationships. It was active in spines that are found on mouse penises. The spines appear to play a role in species where several males compete for individual females: male chimps have penile spines, while human males do not. No one really knows what they are for, but if losing them made sex less painful, that might have contributed to the creation of stronger emotional bonds between men and women, boosting monogamous relationships.

All of these examples of how non-coding DNA could have shaped human evolution are suggestive rather than definitive. It’s hard to prove cause and effect in human evolution, says Prabhakar, because you can’t experiment on humans. But a new genetic megaproject could make the case a lot stronger.

Human Genome Project-Write (HGP-Write) aims to build a human genome from scratch. According to Jef Boeke at the New York University Langone Medical Center, one of the researchers behind the project, exploring the role of non-coding DNA will be among its most interesting applications. As the team pieces together a complete human genome, they will be able to delete non-coding segments one by one and see how that affects cells, he says.

That could lead to tangible benefits. Renewed efforts to grow human organs in pigs, and so make up for the shortfall in organ donors, rely on injecting human stem cells into pig embryos. But exactly how those human cells manage to mature into a human organ inside a newborn piglet is still mysterious. HGP-Write could help us understand what’s going on and finesse our organ-growing efforts.

There’s an enormous amount of work still to be done before we really understand how our genome gave rise to unique human characteristics, but the idea that the process starts and ends with genes has never looked more misguided. “Clearly when it comes to turning trillions of cells into a walking, talking human, it’s not the 20,000-strong protein set alone that’s going to get you there,” says Mattick. The answers, it seems, are buried in the trash.


What do you mean, junk?

It was the evolutionary biologist Susumu Ohno who popularised the term “junk DNA” in the early 1970s. At the time, researchers had begun to realise just how much non-coding DNA there is kicking about in our genome. It didn’t code for proteins, but what other purpose it might serve was a mystery.

“The classic argument was: if it’s that abundant and not functional, natural selection would have got rid of it,” says T. Ryan Gregory at the University of Guelph in Ontario, Canada. Ohno dared to question that idea. Non-coding DNA, he said, really was mostly just junk.

The debate continues to this day. Most evolutionary biologists say the evidence in large part backs Ohno’s view. We now know, for instance, that some non-coding DNA acts almost like a parasite, randomly copying and pasting itself into new locations in the genome without apparently altering the way the genome functions. That shows a large fraction of our genome really is useless, they say, with no role to play in human evolution or development.

But some human geneticists take the opposite view. They say the assumption from the early 1970s is correct, and most supposed junk DNA does influence our biology. That’s true for at least some of the junk (see main story), but we still don’t know exactly how much.

@темы: Интересности, Мысли вслух, Наука

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Комментарии
2016-09-23 в 08:06 

[Ари]
Question everything / Все подвергай сомнению - только так ты не разучишься думать
На эту тему есть хорошая книга на русском, "Сумма биотехнологий" Панчина. Я как раз читаю сейчас, он достаточно просто и очень интересно все объясняет.

2016-09-23 в 11:41 

La Franc
Идиотизм вечен.
И я вот хотела добавить, что мы еще не уверены, что этот генетический мусор, тк мы просто пока не в курсе зачем он там, и очень может быть, что он там очень даже нужен.

Вообще начитавшись Quora и отзывы врачей и нейробиологов, мне как-то стало слегка не по себе, тк в основном они говорят, что мы знаем так мало, что прям чудо какое-то, что они еще могут лечить людей и часто это практически методом тыка. Поэтому все то, что там известно сейчас, может все неправда будет скоро. Как получилось с low fat diet эпопеей, которая в итоге оказалась в 10 раз хуже, чем если бы народ ел нормальную еду, а они не вытаскивали жир, чтобы сахарку добавить.

Но ты обязательно расскажи как прошло!

2016-09-23 в 14:42 

Bats
Вау, интересно, буду ждать рассказа!

2016-09-23 в 21:28 

Морана С.
Умные мысли преследуют меня. Но я быстрее!
У меня подруга микробиолог, она рассказывала, что то, что понимает обыватель под ГМО вообще не соответствует действительности.
Мы читаем, что помидор скрестили с каракатицей и в голове возникают всякие ужасы, а особо впечатлительные граждане начинают писать статьи о том, что мы все умрем неизвестно как все это повлияет на следующие поколения.
А биолог видит две цепочки генов, состоящих из очень похожих участков. И в одном есть ген отвечающий за противостояние определенным вирусам (ну вот есть он у каракатицы почему-то), а в другой — помидорной — вместо этого гена пустота. И если заняться селекцией, то можно лет через 50 абсолюно естественным путем сделать так, что выведется помидор, в котором будет нужная цепочка генов с дополнителной функцией того, что она передается потомству.
А можно взять пробирку и сделать это за два дня. И если положить потом два помидора (один из будущего, без ГМО), а второй вот урожая следующего года, и разложить их на гены, то они будут идентичны.

   

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