Origin Of A Complex Life Form Revealed (Biology)

Ehab Abouheif and colleagues, revealed the steps by which two very distinct organisms—bacteria Blochmannia and the hyperdiverse ant tribe Camponotini— have come to depend on one another for survival to become a single complex life form. Their study showed that the two species have collaborated to radically alter the development of the ant embryo to allow this integration to happen. Understanding how such grand unifications originate and evolve is a major puzzle for biologists. Ehab Abouheif, a biologist and senior author on the paper believes that these insights may lead to a better understanding of the origin of complex organisms.

Credit: CC0 Public Domain

The bacteria Blochmannia and members of the hyper-diverse ant tribe Camponotini have forged a symbiotic relationship that goes back 51 million years in which each species can no longer survive without the other (termed obligate endosymbiosis by biologists). The ants are thought to have initially ingested the bacteria from sap-sucking insects called hemipteran bugs, with whom they share an ecological niche. The bacteria, which live inside the cells of the ant, helps regulate the size distribution of workers in the colony by enhancing the ants’ ability to synthesize nutrition. The ants, in turn, provide the bacteria with a protected cellular environment and ensure their survival from one generation to the next. But how they came together has been unclear until now.

The researchers began to look closely at genes that regulate the germline, the material that contains the genetic information (such as ova and sperm in humans) that is passed from one generation to the next, after observing that the bacteria completely surrounds the germline.

Instead of the germline genes being localized in just one location in the egg like all other insects, now they are in four. No one has ever seen anything like this in any other insect. They were also surprised that the hox genes, which set up the layout of the body and normally come on late in embryo development appeared very early and localize in the same four locations as the germline genes.

The localization of these genes in these 4 different areas creates a system of coordinates in the ant embryo, where each performs a different function to integrate the bacteria.

Working with over 30 closely-related species of ants allowed the researchers to reconstruct the steps in this unification. They discovered that the merger happened in a series of steps, going from embryos where germline genes were localized in only one location, until eventually both germline and hox genes could be found in all four. However, a major surprise was that embryos with two locations of these genes evolved prior to the merger between the two species. This means that there was a pre-existing capacity to evolve new locations within the ant embryos, which the bacteria were then able to exploit to make radical alterations to embryo development and integrate the two species.


References: Rafiqi, A.M., Rajakumar, A. & Abouheif, E. Origin and elaboration of a major evolutionary transition in individuality. Nature (2020). https://doi.org/10.1038/s41586-020-2653-6 link: https://www.nature.com/articles/s41586-020-2653-6

This Is How You Can Remove Unwanted Components From The Cell Nucleus (Biology)

Gene expression in eukaryotes requires the effective separation of nuclear transcription and RNA processing from cytosolic translation. This separation is achieved by the nuclear envelope, which controls the exchange of macromolecules through nuclear pores. During mitosis, however, the nuclear envelope in animal and plant cells disassembles, allowing cytoplasmic and nuclear components to intermix. When the nuclear envelope is reformed, cytoplasmic components are removed from the nucleus by receptor-mediated transport through nuclear pores. These pores have a size limit of 39 nanometres, which raises the question of how larger cytoplasmic molecules are cleared from the nucleus.

This fluorescence image shows a dividing cell with segregated chromosomes (magenta) that are tightly clustered at the cell poles by the protein Ki-67 (green). Credit: Sara Cuylen-Häring/EMBL

Now, the research team from IMBA and the European Molecular Biology Laboratory in Heidelberg has now shown that large components such as ribosomes are in fact removed from the forming nucleus before the nuclear envelope is assembled again. This exclusion process requires the protein Ki-67, which was the focus of an earlier publication in Nature by Sara Cuylen-Haring, group leader at EMBL Heidelberg and the other joint first author of this study.

In this older study it was discovered that Ki-67 was responsible for keeping chromosomes separated in early stages of mitosis by acting as a surfactant. Remarkably, they have now found that it changes its properties at the end of mitosis and performs the opposite function, namely clustering of chromosomes. By coming together into a dense cluster at the end of cell division, chromosomes are able to exclude large cytoplasmic components before the nuclear envelope reforms.

They showed that the exclusion of mature ribosomes from the nucleus after mitosis depends on Ki-67-regulated chromosome clustering. Thus, their study revealed that chromosome mechanics help to re-establish the compartmentalization of eukaryotic cells after open mitosis.


References: Cuylen-Haering, S., Petrovic, M., Hernandez-Armendariz, A. et al. Chromosome clustering by Ki-67 excludes cytoplasm during nuclear assembly. Nature (2020). https://doi.org/10.1038/s41586-020-2672-3 link: https://www.nature.com/articles/s41586-020-2672-3

Universal Mechanism For Ejection Of Matter By Black Holes Is Proposed By Researchers (Astronomy)

Black holes can expel a thousand times more matter than they capture. The mechanism that governs both ejection and capture is the accretion disk, a vast mass of gas and dust spiraling around the black hole at extremely high speeds. The disk is hot and emits light as well as other forms of electromagnetic radiation. Part of the orbiting matter is pulled toward the center and disappears behind the event horizon, the threshold beyond which neither matter nor light can escape. Another, much larger, part is pushed further out by the pressure of the radiation emitted by the disk itself.

Accretion disk (in purple, out of scale). The process occurs in active-core nuclei. A molecular gas cloud that accumulates in the central region is blown away by radiation from the black hole’s accretion disk, forming a huge expanding hot bubble, whose radius can reach 300 light years. Credit: Daniel May

Every galaxy is thought to have a supermassive black hole at its center, but not all galaxies have, or still have, accretion disks. Those that do are known as active galaxies, on account of their active galactic nuclei. The traditional model posits two phases in the matter that accumulates in the central region of an active galaxy: a high-speed ionized gas outflow of matter ejected by the nucleus, and slower molecules that may flow into the nucleus.

A new model that integrates the two phases into a single scenario has now been put forward by Daniel May.

May identified the pattern on the basis of a study of two active galaxies: NGC 1068, which he investigated in 2017, and NGC 4151, which he investigated in 2020. NGC stands for New General Catalogue of Nebulae and Clusters of Stars, established in the late nineteenth century.

Using a highly meticulous image treatment methodology, they identified the same pattern in two very different galaxies. Most astronomers today are interested in studying very large datasets. Their approach was the opposite. They investigated the individual characteristics of these two objects in an almost artisanal manner.

Their study suggests that initially a cloud of molecular gas in the central region of the galaxy collapses and activates its nucleus, forming the accretion disk. The photons emitted by the disk, which reaches temperatures on the order of a million degrees, push most of the gas a long way outward, while a smaller part of the gas is absorbed by the disk and eventually plunges into the black hole. As the cloud is sucked into the disk, two distinct phases take shape: one is ionized owing to exposure to the disk, and the other is molecular and overshadowed by its radiation. They discovered that the molecular part is entirely tied to the ionized part, which is known as the outflow. They were able to relate the two phases of the gas, previously considered disconnected, and fit their morphologies into a single scenario.

The ionized gas derives from fragmentation of this molecular gas,. As it fragments, it is pushed further out in an expanding hot bubble that can be as large as 300 light years in radius. For the sake of comparison, it is worth recalling that this is almost 70 times the distance from Earth to Proxima Centauri, the nearest star to the Solar System.

When they observe the central regions of these two galaxies, they saw this enormous bubble in profile, delineated by its walls of molecules. They saw the walls fragmenting and the ionized gas being driven out. The accretion disk appears as an extremely bright spot. All the information that reaches us from it corresponds to a pixel, so they don’t have enough resolution to discern its possible parts. The black hole is known about only from its effects.

In the ancient Universe there was much more available gas, so the effect of a process such as that described by him was more intense. What he observed in relatively nearby galaxies such as NGC 1068 and NGC 4151 is a mild form of the process that occurred in more distant galaxies, whose active nuclei in the remote past are now detected as quasars.


References: D May et al, The nuclear architecture of NGC 4151: on the path toward a universal outflow mechanism in light of NGC 1068, Monthly Notices of the Royal Astronomical Society (2020). DOI: 10.1093/mnras/staa1545 link: https://academic.oup.com/mnras/article-abstract/496/2/1488/5851281?redirectedFrom=fulltext

Researchers Study How Tumor Cells Divide In The Crowd (Medicine / Oncology)

A team led by Dr. Elisabeth Fischer-Friedrich studied how cancer cells are able to divide in a crowded tumor tissue and connected it to the hallmark of cancer progression and metastasis, the epithelial-mesenchymal transition (EMT).

A mini-tumor of human breast epithelial cells (MCF-7). A dividing cell indicated in green. Credit: Dr. Elisabeth Fischer-Friedrich

Most animal cells need to become spherical in order to divide. To achieve this round shape, the cells must round up and deform their neighboring cells. In a growing tumor tissue, the tumor cells need to divide in an environment that is becoming more crowded than the healthy tissue. This means that the dividing tumor cells likely need to generate much higher mechanical forces to round up in such a densely packed surrounding. Yet, tumor cells seem to be adapted to overcome these difficulties. Scientists led by Dr. Elisabeth Fischer-Friedrich were curious how do the tumor cells gain this enhanced ability to deal with the crowded tumor environment?

The researchers found that the EMT could be one of the answers. What is it exactly? EMT or epithelial-mesenchymal transition is a hallmark of cancer progression. It is a cell transformation during which tumor cells lose their asymmetric organization and detach from their neighbors, gaining the ability to migrate into other tissues. This, together with other factors, allows tumors to metastasize, i.e., move into the blood and lymphatic vessels and ultimately colonize other organs.

So far, EMT has been mainly linked to this enhanced cell dissociation and cell migration. Their results suggested that EMT might also influence cancer cells by promoting successful rounding and cell division. These results point towards a completely new direction of how EMT could promote metastasis of carcinoma in the body.

Just as they test the ripeness of the fruits by squeezing them gently with our hands, the scientists examined the mechanical properties of individual human cells. Except, they squished the cells using an atomic force microscope. This state-of-the-art setup measured properties such as cell stiffness and cell surface tension before and after the EMT. In addition, the group of Dr. Elisabeth Fischer-Friedrich in collaboration with Dr. Anna Taubenberger (BIOTEC, TU Dresden) and Prof. Carsten Werner (IPF, Dresden) cultured mini-tumors and trapped them inside elastic hydrogels to check how mechanical confinement affects cell rounding and division of tumor cells.

The authors identified changes in rounding and growth of the tumor. EMT influenced the cancer cells in two contrasting ways. The dividing tumor cells became stiffer while surrounding non-dividing cells became softer. Furthermore, the researchers found hints that the observed mechanical changes could be linked to the increased activity of a protein called Rac1, a known regulator of the cytoskeleton.

Their findings will not only provide important results to the field of cell biology but may also identify new targets for cancer therapeutics.


References: Kamran Hosseini Anna Taubenberger Carsten Werner Elisabeth Fischer‐Friedrich, “EMT‐Induced Cell‐Mechanical Changes Enhance Mitotic Rounding Strength”, Advance science, 2020 doi:
https://doi.org/10.1002/advs.202001276 link: https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202001276

This Study Finds, Diabetes As A Consequence Of COVID-19 (Medicine / Diabetes)

Tim Hollstein and colleagues in their paper described that, the SARS-CoV-2 coronavirus, which causes the coronavirus disease COVID-19, can penetrate many different body cells. This has been shown in multiple research papers published in recent weeks. Thus, not only can the function of the respiratory tract and the lungs be severely disrupted, but also numerous other organs. The SARS-CoV-2 virus can also penetrate the so-called beta cells in the pancreas and damage them.

Credit: Pixabay/CC0 Public Domain

These cells are responsible for producing the insulin required for a healthy metabolism. A SARS-CoV-2 infection can apparently disrupt this function, which as a result leads to diabetes.

The publication is an initial description of insulin deficiency diabetes after a COVID-19 illness, based on an observed case. They described in their paper that, a 19-year-old white male presented at their emergency department with diabetic ketoacidosis, C-peptide level of 0.62 µg l–1, blood glucose concentration of 30.6 mmol l–1 (552 mg dl–1) and haemoglobin A1c of 16.8%. The patient’s case history revealed probable COVID-19 infection 5–7 weeks before admission, based on a positive test for antibodies against SARS-CoV-2 proteins as determined by enzyme-linked immunosorbent assay.

Such an insulin deficiency diabetes, i.e. type 1 diabetes, is usually triggered by an autoimmune response, in which the immune system incorrectly identifies the beta cells in the pancreas as foreign and attacks them. But this autoimmune response was not present in this patient. They assumed that here, the SARS-CoV-2 virus itself attacked the beta cells.

This also fits with the fact that the beta cells possess a crucial receptor: the ACE2 receptor. The SARS-CoV-2 virus can specifically bind with this receptor. The receptor is also used by the virus as an entry point into the other body cells which it attacks.

However, as noted, no serum autoantibodies were observed against islet cells, glutamic acid decarboxylase, tyrosine phosphatase, insulin and zinc-transporter 8. Although their report cannot fully establish causality between COVID-19 and the development of diabetes in this patient, considering that SARS-CoV-2 entry receptors, including angiotensin-converting enzyme 2, are expressed on pancreatic β-cells and, given the circumstances of this case, they suggested that SARS-CoV-2 infection, or COVID-19, might negatively affect pancreatic function, perhaps through direct cytolytic effects of the virus on β-cells.


References: Hollstein, T., Schulte, D.M., Schulz, J. et al. Autoantibody-negative insulin-dependent diabetes mellitus after SARS-CoV-2 infection: a case report. Nat Metab (2020). https://doi.org/10.1038/s42255-020-00281-8 link: https://www.nature.com/articles/s42255-020-00281-8

Astronomers Monitor Spectral Behavior Of Gamma-Ray Blazar S5 0716+714 (Astronomy)

Chinese astronomers reported the new results of spectroscopic observations of γ-ray blazar S5 0716+714 from 2019 September to 2020 March with the 2.4 m optical telescope at Lijiang Observatory of Yunnan Observatories. Their observations provided important insights into the spectral behavior of this source, finding that it is brightness-dependent.

Fig. The left panel is spectral indices (top) and light curves (bottom). The right panel is interpolation cross-correlation functions

Blazars are very compact quasars associated with supermassive black holes at the centers of active, giant elliptical galaxies, and can exhibit variability on a wide range of timescales. They belong to a larger group of active galaxies that host active galactic nuclei (AGN), and their characteristic features are relativistic jets pointed almost exactly toward the Earth.

Based on their optical emission properties, astronomers divide blazars into two classes: flat-spectrum radio quasars (FSRQs) that feature prominent and broad optical emission lines, and BL Lacertae objects (BL Lacs), which do not.

S5 0716+714 is a typical BL Lac exhibiting extreme variability and a prominent relativistic jet. Previous observations of this object have suggested that it showcases the so-called bluer-when-brighter (BWB) chromatic trend. The BWB chromatism, perceived as an evidence of physical processes in jets, is one of the most common phenomena in BL Lacs. In the case of S5 0716+714, its BWB trends may depend on the brightness, for instance, the correlations at the bright state are weaker than those at the faint state.

In order to further investigate the BWB trends in this blazar, a group of astronomers led by Hai-Cheng Feng of Yunnan Observatories, China, conducted spectroscopic observations of the source with Lijiang Observatory’s 2.4-m optical telescope.

Feng’s team monitored S5 0716+714 during two observation periods (Epoch1 and Epoch2) between 2018 and 2020. In general, the source was observed to show a strong BWB trend, and the correlation between brightness and spectral index was found to become weaker toward the blazar’s brighter state.

According to the study, the data reveal an extremely bright state of S5 0716+714 at Epoch2, and it seems that the BWB trend becomes saturated at the highest state during this observation period. It was noted that the BWB trend of Epoch2 differs significantly from that of the Epoch1.

Trying to explain the spectral behavior of S5 0716+714, the astronomers assume that it may be a result of magnetic field amplification due to the turbulence generated in the post-shock region. They added that the BWB trend in this blazar is seemingly dominated by the relative position changes of the synchrotron peak frequency with respect to the observational frequency range, and effectively may be controlled by the variations of electron average energy and magnetic field in the emitting region.


References: Hai-Cheng Feng, Sen. Yang, Zi-Xu. Yang, H. T. Liu, J. M. Bai, Sha-Sha. Li, X. H. Zhao, Jin. Zhang, Y. B. Li, M. Xiao, Y. X. Xin, L. F. Xing, K. X. Lu, L. Xu, J. G. Wang, C. J. Wang, X. L. Zhang, J. J. Zhang, B. L. Lun, S. S. He, “Spectroscopic Monitoring of Blazar S5 0716+714: Brightness-Dependent Spectral Behavior”, pp. 1-16, 2020. arXiv:2008.11341 [astro-ph.HE] arxiv.org/abs/2008.11341 link: https://arxiv.org/abs/2008.11341

Men With Larger Waists More Likely To die Of Prostate Cancer (Medicine / Oncology)

Dr. Perez-Cornago and colleagues suggested that men who store fat around their midriff are in greater danger of dying from prostate cancer.

A man with 40inch (103cm) waist or above has a 35 per cent higher risk of dying from the disease than one who wears a 35inch (90cm) or lower trouser size.

The Oxford University study, looking at more than 200,000 men, did not find an increased risk in people with higher overall body fat if it was spread around the body.

This suggests it is the specific location of the fat that makes males more prone to the killer disease.

Fat stored in the belly is considered the most dangerous type because it coats vital organs, such as the liver, pancreas and intestines.

This may interfere with their normal function and promote the growth of cancerous cells, the researchers said.

The latest research, presented at this year’s European and International Conference on Obesity (ECOICO), looked at 218,225 cancer-free men in the UK, whose medical data is stored in the UK Biobank.

Scientists monitored them for 10 years, looking at their body mass index (BMI), total body fat percentage, waist circumference, and waist-to-hip ratio.

Men in the top 25 per cent for waist circumference, they found, were 35 per cent more likely to die of prostate cancer than men in the bottom 25 per cent.

The largest group included those whose waists measured more than 40 inches (100cm). The waist does not include the hip bones but is the soft section between the pelvis and the ribs, level with the belly button.


Maybe We Haven’t Found Aliens Because They’re All Sleeping (Astronomy / Aliens)

By now you know what the Fermi Paradox is. If the universe is full of extraterrestrial life (and most scientists think it is, with varying definitions of “full”), then why haven’t we found any aliens yet? One hypothesis says we’re basically exhibits in an intergalactic zoo. When was the last time you wrote a letter to the monkey house’s bonobos?

Another theory says we’re just too stupid for aliens to bother. Thanks for the vote of confidence, Neil.

But here’s a novel idea: what if aliens are out there, but “hibernating” until the universe is more to their liking? Perhaps the truth is out there, but it’s taking a nap.

Feeling confused by the idea that one civilization (or several!) could just be taking a galaxy-wide nap? The theory is that it’s not so much “sleeping” as it is “power-save mode.” That’s because the whole thing hinges on aliens having given up their biological form in favor of a purely digital existence. If that’s the case, then those computerized beings would greatly benefit from an extremely cold environment. Right now, background radiation has the temperature of outer space hovering somewhere around 3 kelvins above absolute zero — not exactly a sauna. But over the course of trillions of years, that temperature will drop even further, eventually approaching (but never reaching) zero. Once that happens, the digital aliens will basically wake up with super-powers.

Anders Sandberg, Stuart Armstrong, and Milan M. Cirkovic, the authors of the paper, calculated that such a digital civilization would be able to produce 1030 times as many calculations per second in the near-zero universe than in today’s world. That’s because every computation has an energy cost, and that cost is closely connected to temperature. With the overall temperature of the universe at an all-time low, these living computers could pull off incredible mental feats for minimal resources.

The only thing is, they’d also be cutting their expected lifespan by trillions of years — why not stay awake and continue to advance while enjoying an ever-more frigid universe? Even Cirkovic thinks the theory isn’t necessarily the best explanation. As he told Slate, “I much prefer hypotheses that do not rely on assuming intentional decisions made by extraterrestrial societies. Any assumption is extremely speculative.” One thing he does think is likely? That alien civilizations are already digitized.

So what makes a digital civilization so likely, and what would such a civilization look like? Well, what it looks like will depend a lot on how it came to be. It may be, as Dr. Steven Dick theorized in 2006, that biological aliens will eventually upload their consciousness into computers to gain greater intelligence and other benefits. But there are other possibilities. A purely artificial intelligence might also be the biggest brain in the galaxy, whether it was built by biological aliens as a friendly supercomputer or a member of an entirely technological race that long ago broke away from anything organic. That sounds…a little terrifying. Here’s hoping they’re getting their sleep.


Neil deGrasse Tyson Thinks Humans Might Be Too Stupid For Aliens (Astronomy / Aliens)

The Fermi paradox—which basically asks: if the universe is so big and old, and there are countless opportunities for life, why have we not found aliens? —has been driving scientists wild for some time. Astrophysicist Neil deGrasse Tyson thinks that aliens may be too smart to interfere with life on Earth. But he also thinks they may already be here…

In a Business Insider video, Neil deGrasse Tyson admits he has “unorthodox thoughts” on the matter of aliens. Where are they? The famed astrophysicist and host of StarTalk Radio poses the possibility that aliens already have visited Earth, but no one noticed. How would we know if we were walking among the masses of people in Times Square and we brushed shoulders with E.T.? But a more serious thought is that aliens may be more intelligent than humans are even able to comprehend. Think of it like this: A worm on the sidewalk is probably unaware that humans, these amazingly intelligent beings, are walking all around them on Earth. Are we the worms wriggling around at the feet of super-smart extraterrestrials?

WHY DO WE CARE ABOUT ALIENS?

Who doesn’t want to know if we’re all alone in the universe? If we are in fact not alone (the chances against which are microscopically tiny), then that means there are other places in the universe that can host life. The possibilities of what to do with that knowledge is virtually limitless.