I subscribe to the New Scientist magazine. Cliché though it may be to say, the magazine’s stories are a constant reminder of the wonderfully unlikely complexity of life and the Universe. In case you might be similarly awed or intrigued, I’m sharing three of my favourite articles from the past year.
CRISPR Gene-Editing Urgently Needs an Off-Switch – Now we have One
Author: Gege Li
Article link (Paywalled)
CRISPR regularly features in the New Scientist. It is a biological tool for gene-editing that won a nobel prize in 2020 for Jennifer Doudna and Emmanuelle Charpentier. With this tool, biologists can cut DNA sequences and so disable a target gene or replace a faulty one. The technique holds massive potential for cures for genetic disease. Although there remain technical, ethical and political issues to work through.
I had not previously understood the biological background to CRISPR. It turns out that CRISPR is a defense mechanism that bacteria evolved against viruses. The viruses that infect bacteria are called bacteriophages or ‘phages’.
The article author explains that CRISPR It is made up of DNA sequences containing genetic code left behind by phages from past viral attacks. When a phage invades again, the bacterium makes RNA copies of these CRISPR regions. This RNA, via an enzyme called Cas, latches on to matching sequences in the invading virus’s genome. The Cas protein cuts viral DNA strand, attacking the phage.
One concern is that gene-editing using CRISPR could have harmful consequences if the technique is not controlled. CRISPR can affect gene sequences that are similar to but not the same as the target sequence. Or, for example, CRISPR used in a gene drive for pest control might have unintended consequences for genetic spread.
Well, while bacteria evolved CRISPR as a defense mechanism, some phages have evolved their own counter mechanism called anti-CRISPR. When these phages infect a bacterium the anti-CRISPR genes are among the first to be expressed and can block a bacterium’s CRISPR response. Researchers have now found away to utilize anti-CRISPR to limit gene editing to a brief period. This allows for more nuanced application of the CRISPR technique.
Research has also demonstrated that anti-CRISPR can be organ specific. In one case anti-CRISPR was developed that was active unless in the presence of RNA found only in liver cells. In effect the CRISPR would only be active in the liver.
For me, the CRISPR arms race between bacteria and bacteriophages is another amazing example of the complexity that can arise through evolution. And it’s equally amazing that we are learning to apply these mechanisms ourselves.
The secret power of the tequila plant that could help feed the world
Author: Larissa Fedunik
Article link (Paywalled)
You might recall that in 2018 there was an agave shortage. Agave is the plant used to make tequila so this was frightening stuff indeed. But while agave gets credit for supplying excellent drinks, you might not realize that it’s also an elite photosynthesizer. This article is about how researchers are investigating whether the type of photosynthesis used by the agave plant can be transplanted into other plants, especially crops, as part of the response to global warming.
I found this article interesting because of the explanation it gave of photosynthesis. It turns out that about 90 per cent of plants, including wheat and rice, use a version of photosynthesis that we call C3, who’s to know what the plants themselves call it. The article explains that C3 as with other versions of photosynthesis relies on an enzyme called rubisco. Rubisco picks up CO2 molecules and combines them with another compound in the first step to the production of sugar. Problematically this doesn’t work 40 per cent of the time as rubisco slips and picks up oxygen instead of CO2 which wastes energy.
Interestingly this wouldn’t have mattered so much 3 billion years ago when rubisco evolved. At that time CO2 would have been much more prevalent in the atmosphere. The process of photosynthesis itself has made oxygen a lot more abundant in the atmosphere so plants have become a victim of their own success.
Some plants have developed alternative versions of photosynthesis, such as those that have evolved C4 photosynthesis.The anatomy of these plants manages to capture and concentrate CO2 molecules before transporting the CO2 to the area where rubisco is released. Because the concentration of CO2 is higher the rubisco is less likely to grab oxygen, so efficiency is enhanced. Although only four per cent of plants use C4 photosynthesis they make up about 23 percent of biomass produced on land, and include grass, maize and sugar cane.
Agave though, is nek level, it uses a third type of photosynthesis called called crassulacean acid metabolism. This process also concentrates CO2 to improve the efficiency of photosynthesis but instead does this by staggering the time intervals of the process. Agave only open their stomata at night to capture CO2 and during the day the plant uses stored CO2 to photosynthesize. The result is that agave and other plants that use this method only need about 20 per cent as much water as the least thirsty C3 and C4 crops.
Clearly, the agave plant is multi-talented. And with global warming increasing the pressure on fresh water supplies its skills might come in handy.
We’ve Got Intelligence All Wrong – and That’s Endangering our Future
Author: Robert J. Sternberg
Article link (Paywalled)
This article takes issue with our concept of IQ as a reasonable measure of intelligence and a fixed trait. I was interested to learn that Alfred Binet, the co-creator of the first modern intelligence test, believed that intelligence is modifiable. He originally devised the test to identify children in schools that were not responding well to regular schooling. These children would then be given different instruction to help up their results. We can say that the test was founded on the idea that intelligence can be developed.
But then English psychologist, Charles Spearman, discovered that the results of various tests he was using to measure mental abilities tended to correlate with one another. These tests tended to measure memory skills and a narrow range of analytical skills such as vocabulary recall, information-processing speed, and the ability to perform numerical operations . Spearman interpreted the correlation of results across these tests to reflect what he called “general intelligence”, or g. Thus was born the idea of intelligence as one largely unmovable number, the guiding principle of IQ tests to the present day.
Many researchers found correlations between Binet-style tests and academic performance. Perhaps not surprising given this was the purpose Binet’s tests. They used academic type problems in order to predict academic performance under regular schooling. But the consequence of these correlations has arguably been that we have made a fully serious effort to independently measure other, broader ability constructs: the ability to think creatively, for example, or to solve practical problems. New tests have been validated against old tests, with a new test labelled “good” if it correlated with old ones. Even though we know there are multiple studies showing that IQ isn’t necessarily a good predictor of typical western markers of broader success in life.
The article author, who is himself a researcher in the field of intelligence, argues that the science of IQ became self-referential. Whereas the characteristics of real-world problems are very different from the characteristics of problems on standardised tests. IQ works best for solving problems that follow familiar or easily learned patterns. It doesn’t work so well for the complex, highly novel, high-stakes, often emotionally charged problems we frequently face.
The author argues that we should embrace the idea that that intelligence is about adaptation. In this sense intelligence consists of different things in different environments. According to where you are in the world or your mode of life, it might be shown in negotiating city life or the environment of a rural farm, or in approaches to ice-fishing or using natural herbal medicines. Adaptive intelligence is something you can learn and is constantly updated by your interactions with your environment. If we think more about our ability to adapt to our environment we might focus more on the abilities that help us solve our real world problems.
For me, adaptive intelligence is a much more healthy and useful concept. It’s time we do away with IQ.
Cheers for reading.
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