What biologists did in 2016 – part one

Kirill Stasevich, "Science and Life"

See links and drawings in the original article

As usual, when taking up the biological and biomedical results of the year, we must immediately say that our review will be incomplete: in any modern science, it is difficult to describe everything that happened in it during the year on a couple of pages of text, and if we talk about biology and medicine, then perhaps a couple of hundred there will be few pages.

You can go the other way, trying to guess future trends and prospects based on the material of the outgoing year, but scientific progress is remarkable for its outstanding unpredictability, so we will leave divination about the future to those who feel more confident in the art of futurology. Our task is much more modest: to recall some, in our opinion, particularly notable works – from those we told you about – and, if possible, group them around certain scientific topics.

Last year and the year before last, our final reviews began with the Nobel Prize – after all, this is one of the main events in the world of science. This year, Yoshinori Osumi became the first winner of the Nobel Prize in Physiology and Medicine – he received it for his research on cellular autophagy, or self-eating (you can learn more about what cellular autophagy is from our article in the November issue of Science and Life).

Sometimes the prize is awarded for works of a purely fundamental nature, sometimes for more applied ones. In the case of autophagy, the applied prospects of Osumi's research are in no way inferior to their fundamental importance: on the one hand, "self–eating" is a universal property of all eukaryotic cells, on the other hand, defects in autophagy lead to a variety of diseases, from oncological to immune.

And since we mentioned oncology, we will continue our review with "cancer" articles. One of the most unpleasant features of malignant tumors is their ability to metastasize. Oddly enough, sometimes our own immunity contributes to the formation of metastases. So, in October, an article was published in Science Translational Medicine, which stated that antibacterial trapping nets, which immune neutrophils make from their own DNA, help metastatic tumor cells penetrate into healthy tissues.

But still, the immune system usually makes sure that cancer does not spread throughout the body, and if this suddenly happens, it means that something is wrong with the immune system: the authors of another article from Science Translational Medicine, published in the spring of this year, found that malignant tumors spread throughout the body not so much because of special metastatic mutations, how many due to weakened immunity. Among other factors contributing to metastasis, fat and antioxidants can be indicated, in this case, diabetes medications that reduce the level of oxidative stress. (Given that oncologists have long known about the ambiguous role of antioxidants in the development of tumors, this is not surprising.)

As for the common causes of malignant diseases, there is quite a lot of talk about the role of "silent inflammation", which is imperceptibly smoldering in the bowels of the body. Sometimes we ourselves, with our improper diet and generally unhealthy lifestyle, help cancer – for example, some tumors can occur with alcohol abuse and circadian rhythm disorders. A separate topic is cancer genetics: although it is clear that tumors begin with mutant cells, determining the mutational portrait of cancer is not an easy task. On the one hand, different types of tumors have their own characteristic genetic defects, on the other hand, some features of tumors arise due to the fact that "alien" mutations appear in them.

In general, all the works devoted to oncological diseases have one thing in common – an attempt to find a vulnerable place of the disease. And even if we learn something like that cancer cells go in gangs, or that it is inconvenient for cancer cells to divide in a tight space, it is assumed that both can be used somehow against the tumor itself. As for more specific proposals, it is clear that a great many drugs and therapeutic approaches are tested in the world every year.

We will remind readers of only three works of this kind: firstly, researchers from the University of California at Berkeley found out that thrice negative breast cancer can be weakened if you put the tumor on a "starvation ration", and secondly, most recently, in December, an article appeared in Nature Medicine, which stated that fasting destroys leukemic cells – at least in mice; thirdly, a rather peculiar way of fighting cancer was proposed by specialists from the M. D. Anderson Cancer Center in Texas, who literally set cancer on themselves.

In modern biology and medicine, it is sometimes very difficult to discuss one area in isolation from another, and now, talking about oncology, we periodically recalled about immunity, about genes, about a healthy lifestyle. Let's continue with immunity, about which everyone is usually interested in how it can be improved.

Well, there's a whole list of tools to choose from: blue light, interesting life, high social status; if the status is low and there is no blue light at hand, as luck would have it, you can just try to get pleasure from something. Just in case, we should clarify that a good immune system is one that works not too hard and not too weak, but just right; precise regulation is important in the immune system so that its response to the problem is proportionate and adequate to this problem.

The notorious chronic inflammation is an example of just a poorly functioning immunity (despite the fact that the inflammatory reaction itself is a weapon of defense and attack against a variety of pathogens and infected cells). Inflammation is a dangerous thing, because of it, as we said above, the chances of cancer, as well as cardiovascular and metabolic disorders increase. Even depression can occur due to inflammation - although conventional anti–inflammatory drugs are unlikely to help here.

Another sign of good immunity is the ability to build relationships with the intestinal microflora. We know that the intestinal microflora is given the widest powers in our body, especially with regard to metabolism: it is believed that depending on the composition of the microflora, obesity and diabetes may or may not happen in us. Moreover, more and more data is gradually accumulating in favor of the fact that bacteria can actively interfere with the work of the nervous system – for example, in May we wrote that normal microflora is needed in order for new neurons to appear in the brain.

The immune system, interacting with intestinal bacteria, can also affect metabolism: in the fall, an article by researchers from the University of Oregon appeared in Nature Communications, who found that, depending on the level of interferon in the digestive system, there are fewer or more symbiotic bacteria living in it, on which glucose metabolism depends.

In order for the microflora itself to feel good and behave well, it needs to be fed the right food – it is known that the more diverse the microflora, the better for its owner, and the diversity of intestinal microbes increases from vegetables, fruits, yoghurts, coffee, tea and wine. Another way to improve the microflora is to let parasitic worms into the intestines, but few people will dare to take such a step.

In the past year, we have learned something new about the molecular and cellular mechanisms linking obesity and diabetes - it turned out that the death of fat cells with excess weight stimulates an immune inflammatory response, which, in turn, can lead to diabetes. Obesity can occur, for example, due to the fact that, for genetic reasons, the liver poorly absorbs lipoproteins floating in the blood. Although, perhaps, the most obvious reason for the appearance of excess weight is overeating.

Why do we eat more than we should? For example, because we were unlucky with a mutation, because of which there is a love for fat, or because of artificial sweeteners, or simply because of lack of sleep - because of lack of sleep, the level of endocannabinoids in the body increases, which make us lean on delicious, but unhealthy food.

Since we remembered about the dream, it's worth saying a few words about it. Strangely enough, neuroscientists are still trying to understand why we fall asleep and wake up – one of the latest papers on this topic talks about the neurotransmitter dopamine, an excess of which simply blocks the sleep signal in the brain. (We emphasize that we are not talking about the state of sleep and not about the state of wakefulness, but about switching between them, about moving from one to the other.)

In addition, researchers from the University of California at San Francisco once again reminded us that sleep helps fight infections, and colleagues from Brown University found out why we sleep poorly in a new place - it turns out that in an unfamiliar environment, our brain keeps one hemisphere in a "half–awake" state out of vigilance.

It would be logical to move from sleep to the brain. One of the most popular "brain" topics was and remains memory. Memory has a lot of varieties: long–term, working, episodic (storing "life cases"), spatial, etc.; and it can be studied at various levels - at the level of individual neurons, neural networks, large areas of the brain, or in the form of cognitive-psychological manifestations.

So, in the spring, an article was published in the journal Neuron, the authors of which talked about how new neurons help old ones focus on specific information, thanks to which memory becomes better. On the other hand, different neurons literally compete for memory: information that is related to the same subject or situation is recorded in the brain by the same neurons that do not allow competitors from other neural networks to access this information.

Another intriguing problem is the transformation of short–term memory into long–term memory during sleep: the transfer of information from one storage to another occurs during a dialogue between different memory centers; our "periphery" also plays a role here - in the summer, an article appeared in PNAS magazine about how the heart helps the sleeping brain to work with memory.

It is believed that the recording of new information in neural circuits is accompanied by increased activity of some genes, so here it is impossible not to recall the somewhat unexpected work of researchers from the University of Washington, who found that in order for memory to work properly, some genes should, on the contrary, be silenced. How can I improve my memory? For example, be less nervous and eat less fat.

But memory is not the only function of the brain: we not only remember a lot of things, we also perceive the environment, we think, analyze, etc. Given the enormous complexity of both the outside world and our own psychology, is it any wonder that the functions of some nerve cells are still unknown to us. Although progress is moving in all directions here: so, in the past year, "neurons of heat" and "neurons of loneliness" were found in the brain.

But despite the fact that the variety of nerve cells that differ from each other not only in function, but also in appearance, is constantly growing, among them, curiously, one can single out an "elite" holding a certain monopoly on information entering the brain – in an article in The Journal of Neuroscience, which was published in at the beginning of the year, it is said that in the cerebral cortex, only 20% of neurons pass through themselves as much as 70% of the entire information flow.

A separate big topic in neuroscience is brain plasticity. It has long been known that the brain, formed in youth, nevertheless continues to change for the rest of its life, adjusting to various circumstances. The changes can be purely functional (here we can recall the curious work of researchers from the University of Liege, who found that the brain works differently in winter and summer), or they can directly affect the structure of the brain - in this case, you can see how, for example, the level of gray matter changes in certain parts of it. Here, of course, it is impossible not to recall two works describing changes in the female brain: one says that in women it changes periodically every month, and the other – how the brain changes during motherhood.

One of the most unkillable questions that neuroscientists have to hear is whether mobile phones harm the brain. I must say that although medical and epidemiological studies have not confirmed the link between the probability of brain tumors and the intensity of mobile phone use, the topic still pops up from time to time.

In particular, in May we talked about some experimental work in which we observed laboratory animals receiving certain doses of "mobile radiation" – however, the results turned out to be so strange (in particular, it turned out that due to "mobile waves" you can either get cancer or become a long-lived person) that these the data is hardly worth it.

But a much, much more serious issue related to brain health concerns well–known neurodegenerative diseases - Alzheimer's disease, Parkinson's syndrome and others. Unfortunately, it is still unclear how to treat them, although we already know quite a lot about what happens in the brain affected by neurodegenerative processes (by the way, in the outgoing year, researchers managed to find out in more detail why memory fails in Alzheimer's disease).

Some therapeutic approaches may be quite successful – for example, the use of antibodies against pathogenic proteins accumulating in diseased neurons, or "light therapy" described in a recent article in Nature (read more about both methods in the January issue of Science and Life) – but before full-fledged clinical trials, talk about "a cure for the disease Alzheimer's" would be very premature.

It is known about neurodegenerative diseases that they manifest with age, and here it would be appropriate to move on to aging and stem cells – however, we will leave these topics for the second part of our review.

Portal "Eternal youth" http://vechnayamolodost.ru   28.12.2016