In this week’s Sunday Science, super-vision in deep sea fish, a breakthrough in 3D printing organs, human mutation, improved recyclable plastics, and why eating broccoli is good for you…Many animals that live in completely dark regions of the earth, such as caves, are blind, given that eyes are useless (and energetically expensive) where there’s no sunlight at all. In the ocean, it was generally found that the further down you go, the less light there is and the simpler eyes become – but not in all cases, apparently. Some deep sea fishes from different lineages have evolved photoreceptor cells that can capture every single possible wavelength of light, possibly to take advantage of the bioluminescence produced by other animals. The genes encoding light-detecting proteins called opsins have expanded and diversified over time. A summary can be found here, and the original study here (both paywalled, unfortunately).
An exciting breakthrough in the development of artificial organs – specifically 3D printing them (yes, it sounds like science fiction, but it’s real). 3D printing tissue is not that new, but making anything large or complex always stalled because of the need for a blood supply to deliver nutrients and oxygen. The team took a novel approach of using natural and synthetic food dyes to absorb specific wavelengths of light, allowing for precision sculpting of the hydrogel they made the blood vessel network in. This week’s featured image is of a scale model made of a lung air sac, with a completely separate blood and airway system. Incredible. Original article here. This is paywalled, but all source data on the experiments is freely available for people to use.
Mutations in DNA occur, partly as a consequence of a copying process that (like any copying process) is not 100% error free, but also in response to damaging agents like UV or cancer-causing chemicals. Often, these mutations are either silent (they don’t affect protein function) or damaging. Those that occur in the germline and are passed to the next generation via sperm and eggs also provide the raw material for evolution, however. It was always assumed that a lot of these mutations are in sperm from the father. The reason for this is that sperm are made continuously over an adult male’s lifetime, meaning many more rounds of DNA copying that can cause mutations (particularly in older males as it becomes less efficient). This is linked to an increased risk of neurodevelopmental disorders (particularly schizophrenia) in the offspring in older fathers. In women, the eggs all form in the embryo and are paused until fertilisation – this increases the risk of chromosomal problems in older mothers, e.g. Down syndrome, but lessens the risk of these changes in the DNA. So I tell my students. But apparently this isn’t really the case. A new analysis (open access) reveals that even young fathers contribute a substantial number of mutations – and mothers may contribute more than previously thought too. It appears that damage to the DNA is actually a key factor.
Eating your greens is good for you, most people know this. Consumption of broccoli and related cruciferous vegetables is known to reduce the risk of cancer. Now researchers have uncovered why. These vegetables contain a compound which inhibits an enzyme which normally functions to switch of PTEN, a key “tumour suppressor” protein. When mutated to non-functionality, PTEN can cause cancers. So this compound in broccoli helps stimulate the activity of PTEN. Original study published here (paywalled).
People are becoming increasingly aware of the vast amounts of plastic we consume – and fail to recycle. One of the problems with some plastics is that they can’t be recycled. Specifically, thermosetting plastics, in which the molecules form crosslinks, can’t be recycled, but this molecular stability gives them a number of useful properties (like solvent resistance) than the other major class of plastics, thermoplastics. These don’t form crosslinks and are more easily recycled, but are not that useful for high-end applications such as in electronics or cars. Thermosets currently account for 15-20% of global plastic production – which is currently running at around 300 million tonnes, so that’s not an insignificant amount. A new procedure designed polymers that form dynamic crosslinked networks based a different type of bond called diketoenamine bonds. These plastics can be produced very easily in a solvent-free process, and, importantly, can be broken down to their constituent units by treatment with a strong acid and re-used. Original article here (paywalled)
And finally, a depressing new milestone has been reached: the highest atmospheric carbon dioxide concentration on Earth since humans evolved – that’s over 200,000 years ago. The Mauna Loa Observatory, recorded a concentration of 415.26ppm of carbon dioxide in the air on 11 May.
A bioprinted scale-model of a lung-mimicking air sac with airways and blood vessels that never touch yet still provide oxygen to red blood cells. Credit: Photo by Jordan Miller/Rice University, via Science magazine.