Genetically Engineered Silkworms Spin Super Strong Partly-Spider Silk

Scientists have taken a new step towards mass-producing spider silk, an incredible material whose potential we haven’t been able to harness quite yet. From Not Exactly Rocket Science:

Spider silk is a remarkable material, wonderfully adapted for trapping, crushing, climbing and more. It is extraordinarily strong and tough, while still being elastic enough to stretch several times its original length. Indeed, the toughest biological material ever found is the record-breaking silk of the Darwin’s bark spider. It’s 10 times tougher than Kevlar, and the basis of webs that can span rivers.

Because of its enticing properties, spider silk has enormous potential. It could be put to all sorts of uses, from strong sutures to artificial ligaments to body armour. That is, if only we could make enough of the stuff. Farming spiders is out of the question. They are territorial animals with a penchant for eating each other. It took 82 people, 4 years and 1 million large spiders to make a piece of cloth just 11 feet by 4 feet…

As a large industry and centuries of history can attest to, silkworms are easy to farm in large numbers. And they’re silk-spinning machines, with massive glands that turn silk proteins into fibres…

Fraser had just the right tool for the job. In the 1980s, he identified pieces of DNA that can hop around insect genomes, cutting themselves out of one location and pasting themselves in somewhere else. He named them PiggyBac, and he has turned them into tools for genetic engineering. You can load PiggyBac elements with the genes of your choice, and use them to insert those genes into a given genome. In this case, Florence Teulé and Yun-Gen Miao used PiggyBac to shove spider silk genes into the silk-making glands of silkworms…

These engineered silkworms produced composite fibres that were mostly their own silk, with just 2 to 5 percent spider silk woven among it. This tiny fraction was enough to transform the fibres. They were stronger, more elastic, and twice as tough as normal silkworm fibres. And even though they didn’t approach the strength and elasticity of true spider silk, they were almost just as tough…

The team are also planning to refine their technique to take the silkworms’ own proteins out of the equation. “The next step will be to produce silkworms that produce silk fibres consisting entirely of spider silk proteins,” says Jarvis. Perhaps they could even use the genes from the best of the silk-producers, like Darwin’s bark spider.

Seems like a promising approach; maybe commercial products using spider silk are in our not-too-distant future. Something tells me it won’t be marketed as “spider web” though, so I’m curious to see what companies will call it when they commercialize it. 

You can read about that 11×4 ft cloth made by farming actual spiders at Wired here; the process involved capturing a million spiders off of the street in Madagascar. I previously talked about an art project mixing spider silk and human skin, where the combination was strong enough to take a hit from a bullet at reduced speed. Cool things (not human spider cool, but other kinds of cool) are in our future.


Blinking Bacteria As Biological Sensors

You’re probably aware that making lab organisms – or at least parts of them – glow a certain colour is relatively commonplace. Biologists frequently attach the gene for green fluorescent protein (GFP) or its differently coloured family members to a gene that they’re interested in, so whenever the gene of interest is activated GFP is produced and the relevant target fluoresces, a nice visible marker. 

In the last few years a group of researchers found a way of tying fluorescence to the cycle of bacteria’s biological clocks, producing rhythmic blinking. Last year they managed to coordinate this blinking in large groups of bacteria, which they compare to living neon signs. Now, they’ve shown that this system can be used as a living sensor for environmental pollutants.

From ScienceDaily:

Using the same method to create the flashing signs, the researchers engineered a simple bacterial sensor capable of detecting low levels of arsenic. In this biological sensor, decreases in the frequency of the oscillations of the cells’ blinking pattern indicate the presence and amount of the arsenic poison.

Because bacteria are sensitive to many kinds of environmental pollutants and organisms, the scientists believe this approach could also be used to design low cost bacterial biosensors capable of detecting an array of heavy metal pollutants and disease-causing organisms. And because the sensor is composed of living organisms, it can respond to changes in the presence or amount of the toxins over time unlike many chemical sensors.

“These kinds of living sensors are intriguing as they can serve to continuously monitor a given sample over long periods of time, whereas most detection kits are used for a one-time measurement,” said Jeff Hasty, a professor of biology and bioengineering at UC San Diego who headed the research team in the university’s Division of Biological Sciences and BioCircuits Institute. “Because the bacteria respond in different ways to different concentrations by varying the frequency of their blinking pattern, they can provide a continual update on how dangerous a toxin or pathogen is at any one time.”

They go on to explain that there are too many bacteria on their “microfluidic chips” (up to 60 million cells) for the bacteria to all coordinate in their usual way, which is called quorum sensing (roughly, relaying signaling molecules between them). They found, though, that colonies released gases that could be used to coordinate between them, while cells within colonies still coordinated by quorum sensing.

This is a pretty interesting idea. I trust biologists to be able to make bacteria sensitive to various molecules and react in various ways; I see no reason why bacteria wouldn’t be able to glow different colours based on the environment, for example. There may be more possibilities with living versus non-living sensors simply because of the incredible complexity of living things, which we can take advantage of without reconstructing from the ground up.

“Lab-Grown Blood Given to Volunteer For the First Time”

From New Scientist:

RED blood cells generated in a lab have been successfully injected into a human volunteer for the first time. This is a vital step towards a future in which all the blood we need for transfusions can be made in the lab, so that blood donors are no longer essential.

Luc Douay at Pierre and Marie Curie University, Paris, and his colleagues extracted what are called hematopoetic stem cells from a volunteer’s bone marrow.

Hematopoietic stem cells are cells that can turn into any kind of blood cell. They’re a step in the path between embryonic stem cells, at the least differentiated extreme, and a specific type of blood cell, at the most differentiated extreme.

These cells were encouraged to grow into cultured red blood cells using a cocktail of growth factors. After labelling the cells so they could be traced, Douay’s team injected 10 billion – the equivalent of 2 millilitres of blood – back into the original donor to see how they survived…

“The results show promise that an unlimited blood reserve is within reach,” says Douay. That blood reserve is needed urgently. Although blood donations are increasing in many developed countries, blood banks struggle to keep up with the demands of ageing populations who need more operations – often involving blood transfusions. And a source of HIV-free blood is essential in countries with high rates of HIV infection…

Douay’s next challenge is to scale up production to a point where the cultured blood cells can be made quickly and cheaply in sufficient quantities for blood transfusions. The 10 billion cells his team made wouldn’t go very far – a transfusion typically requires 200 times that number. With his existing technology, Douay estimates that a single transfusion would require 400 litres of culture fluid, which is clearly impractical. “We are still a long way from the vision of dropping a couple of stem cells into the broth and making endless units of blood,” says John Hess of the University of Maryland in Baltimore.

Douay believes that it may take several years to scale up the technology. Another possibility is to use embryonic stem cells instead, as Lanza did in 2008. “We can generate up to 100 billion red blood cells from a single six-well plate of stem cells,” Lanza says. He also claims to have made red blood cells through yet another technique: generating “induced pluripotent” stem cells from skin samples and coaxing those stem cells into becoming blood cells.

This sounds like great news. Blood donations are always in need; supplementing those with lab-created blood should be a relief for patients in need of transfusions. New Scientist also gave us this handy-dandy timeline of the path to artificial blood, for your learning pleasure:

If you’re wondering what the “Rhesus blood group” it’s referring to above means, it’s a property of different blood types, part of which we’re familiar with by the positive/negative classification of our blood.

Rats Learn Reflex With Artificial Cerebellum-On-A-Chip

Researchers at Tel Aviv University developed a chip that could accurately receive input from a rat’s brainstem and send its own signal to another area of the brainstem to initiate muscle movement. 

From New Scientist:

To test the chip, they anaesthetised a rat and disabled its cerebellum before hooking up their synthetic version. They then tried to teach the anaesthetised animal a conditioned motor reflex – a blink – by combining an auditory tone with a puff of air on the eye, until the animal blinked on hearing the tone alone. They first tried this without the chip connected, and found the rat was unable to learn the motor reflex. But once the artificial cerebellum was connected, the rat behaved as a normal animal would, learning to connect the sound with the need to blink.

This is very cool – a device in direct two-way communication with the brain? – but the article is very sparse on actual details, and a quick search hasn’t turned up any other articles on this experiment just yet (this article is from today). I’d like to know how exactly the chip dealt with nervous system signals, particularly in light of the article I posted last week discussing the difficulty of machine-nervous system communication. How did they deal with that in this case? I’ll probably check later to see if any other articles have any more details, and edit in an explanation here if I find one.

For context, this reflex (the very famous classical conditioning) is obviously on the very simple end of brain activity that they could emulate, and in a simpler brain than a human’s; this is still far far away from anything that would be useful for humans, but that’s the way it goes. Science requires patience and more than a few dead-ends.

Human Skin and Spider Silk Stop Bullets

We’ve known for a while that spider silk is incredibly strong – stronger than steel, and tougher than Kevlar (Wikipedia informs me that strength and toughness are not the same thing… roughly, spider silk’s tensile strength means it’s hard to pull apart until it breaks, its toughness means it’s hard to hit until it breaks). 

Now a Dutch artist came up with the idea of mixing human skin and spider silk, and shooting a bullet at it – what, that’s not a normal thing to think of? Check out a video demonstration here, and an article on it here.

So what happened? The artist and a cell biologist she somehow roped into this grew human skin in a lab, and grafted spider silk between the dermis and epidermis. The spider silk was from American genetically modified goats and worms, which is probably a story for another time. They shot bullets at it from a .22 caliber rifle; it did not survive a normal shot, but it did take one at “reduced speed”. 

This whole event was for art, not for any practical purpose, so there are no obvious future implications of its findings. It’s so crazy though and so evocative of the image of genetically modified bulletproof humans, that I just had to share it. 

Scientists take first step towards creating ‘inorganic life’

ScienceDaily brings us a “new way” of making inorganic-chemical-cells; in the future, researchers envision self-replicating, evolving cells made from inorganic chemicals, analogous to organic cells. 

Scientists at the University of Glasgow say they have taken their first tentative steps towards creating ‘life’ from inorganic chemicals potentially defining the new area of ‘inorganic biology’.

Professor Lee Cronin, Gardiner Chair of Chemistry in the College of Science and Engineering, and his team have demonstrated a new way of making inorganic-chemical-cells or iCHELLs.

Prof Cronin said: “All life on earth is based on organic biology (i.e. carbon in the form of amino acids, nucleotides, and sugars, etc.) but the inorganic world is considered to be inanimate.

“What we are trying do is create self-replicating, evolving inorganic cells that would essentially be alive. You could call it inorganic biology.”

Evolving inorganic microorganisms, eh? Sounds like the stuff of sci-fi horror 😉   

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