Highlights

Every year, a committee of experts sits down with a tough job to do: from among all ICREA publications, they must find a handful that stand out from all the others. This is indeed a challenge. The debates are sometimes heated and always difficult but, in the end, a shortlist of  the most outstanding publications of the year is produced. No prize is awarded, and the only additional acknowledge is the honour of being chosen and highlighted by ICREA. Each piece has something unique about it, whether it be a particularly elegant solution, the huge impact it has in the media or the sheer fascination it generates as a truly new idea. For whatever the reason, these are the best of the best and, as such, we are proud to share them here.

LIST OF SCIENTIFIC HIGHLIGHTS

Format: yyyy

  • RNA structure drives proteins crazy (2019)

    Tartaglia, Gian Gaetano (CRG)

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    RNA structure drives proteins crazy

    Messenger RNA (mRNA) is a molecule composed of nucleic acids that transfers the genetic information contained in DNA to produce the proteins that ensure the correct biological operation of every type of cell.  

    We found that messenger RNA could act as a solubilizer, blocking the formation of protein aggregates that are potentially toxic to our organisms.  In particular, we observed that the transcript conding for Heat Shock Protein 70 (HSP70) interacts with many proteins and has a strong effect on protein aggregation.

    We experimentally demonstrated for the first time that, under conditions of stress, HSP70 mRNA has the ability to promote the removal of the protein aggregates that are responsible for serious neuro-degenerative diseases such as Alzheimer’s and Amyotrophic Lateral Sclerosis.

  • On Genetic Inheritance Associated with the X Chromosome (2019)

    Tartaglia, Gian Gaetano (CRG)

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    On Genetic Inheritance Associated with the X Chromosome

    The determination of sex in mammals, and therefore in humans, is defined by the presence of sexual chromosomes: males carry a heteromorphic pair of chromosomes (XY) and females have two identical chromosomes (XX). A specific biological process called inactivation of the X chromosome involves the loss of function of one of the two chromosomes of the females: in this way the quantity of the inherited genes is balanced, avoiding the overexpression of their products (proteins) and the consequent onset of genetic anomalies like the triple X syndrome, also known as trisomy X.

    We analyzed the process of inactivation of the X chromosome and in particular the role of the RNA molecule called Xist (X-Inactive-Specific-Transcript), its main regulator.

    We studied the mechanism of action, structure and interactions of the Xist molecule. We observed that Xist acts as a "scaffold", it provides scaffolding and at the same time attracts lots of proteins to organize the "silencing" of the X chromosome. The interaction network is so great that Xist and its partners proteins form a structure that resembles a corpuscle, conceptually similar to a drop of oil in water.

     

  • Mysterious synchronised pulses of radiation detected from a pulsar for the first time (2019)

    Torres, Diego F. (CSIC - ICE)

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    Mysterious synchronised pulses of radiation detected from a pulsar for the first time

    Pulsars are highly magnetised, fast spinning neutron stars – the relics of massive stars. They are very dense objects, comprising up to two times the mass of the Sun within a radius of only ten km.

    The discovery was made as part of a two-day observation campaign with X-ray satellites and optical telescopes from Earth. This combination allowed the international team to measure with very high temporal resolution the two types of radiation coming from the pulsar.

    The pulsar analysed in this study, J1023+0038, spins around its axis within a few thousandths of a second. Such pulsars are classed as millisecond pulsars, some of which are also sucking in matter from a companion star.
     
    Earlier studies had shown that this pulsar belongs to the rare category of so-called ‘transitional millisecond pulsars’ that switch between two different modes of emissions – in X-rays and radio waves.
     
    The latest data show that the optical pulses in J1023+0038 appear and disappear at exactly the same time as the X-ray ones.
     
    Until now, we thought that the pulsed X-ray emissions originated in a different process than the optical radiation: the accretion of matter from the companion star gives rise to the pulsed X-ray emissions, while the radio signal is thought to result from the rotation of the pulsar’s magnetic field.

    We also expected these processes to take place one after the other, but the synchronised pulses are an indication that they have the same origin.

    To explain this behavior this work develops a new idea: the pulsar's strong electromagnetic wind interacts with the accretion disc around the system at a very close distance from the pulsar, giving rise to the concept of mini pulsar wind nebula.

    This transitional pulsar is one of the most interesting sources we know. Its multi-frequency variability is incredibly rich, and allows us to study the relationship between the magnetic field and matter in extreme conditions.

    [*] Text based on ESA, XMM, CSIC, INAF, IEEC and other press releases on this topic, echoed in different media and news outlets around the world.

  • Binucleated epicardial cells key in heart regeneration (2019)

    Trepat, Xavier (IBEC)
    Raya Chamorro, Ángel (IDIBELL)

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    Binucleated epicardial cells key in heart regeneration

    After an acute heart lesion, such as a myocardial infarction, the human heart is unable to regenerate. The adult cardiac cells cannot grow and divide to replace the damaged ones, and the lesion becomes irreversible. But this does not happen in all animals. For example, zebrafish can completely regenerate its heart even after 20% ventricular amputation.

    This extraordinary regenerative capacity has attracted the attention of researchers from all over the world, who see the range of possibilities that would be opened up if this mechanism of cell regeneration could be applied in human therapies. In collaboration with the team led by Angel Raya, we discovered a surprising mechanism by which zebrafish heart cells move and divide during regeneration.

    We focused on the epicardium, which is the layer of cells on the outer surface of the heart. Although the epicardium cells represent only a small fraction of the heart’s mass, they play a fundamental role in its regeneration. This tissue is the origin of several of the heart’s cell types, and secretes biochemical signals that tell the cells what they have to do at all times. It’s a kind of regeneration ‘hub’.

    After a heart lesion, the epicardium cells begin to divide and move en masse to cover the wound. We observed that, during this process, the cells become binucleated: they duplicate the genetic material and separate it into two nuclei, but they are not divided into two independent cells.

    We discovered that the mechanism by which cells become binucleated has a biomechanical origin. Once DNA has already separated into two nuclei, most animal cells form a contractile ring at its centre. As it contracts, this ring divides the mother cell into two daughter cells. In the case of the heart cells of the zebrafish, our study shows that the ring adheres to the fibres of its environment so that it cannot contract. The result is that the two daughter cells cannot separate despite having duplicated their DNA.

    Multinucleation is a well-known phenomenon in cancer, because it is a cause of genetic instability. In the zebrafish heart, multinucleation is physiological and may be advantageous.

  • A climate club for effective global governance (2019)

    van den Bergh, Jeroen (ICTA-UAB)

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    A climate club for effective global governance

    The Paris Climate Agreement relies on voluntary action by countries as it was impossible to achieve global policy coordination among all countries. As a result, national climate policies remain weak. A climate club or coalition of countries has been suggested as a means to move towards more effective global governance. It would involve uniform policy, most likely carbon pricing. The club could attract further membership by imposing penalties on imports from non-members, to limit competition from unregulated sources. Through economic and moral pressure, it would then expand. In addition, it could speak with a single, powerful voice at UN climate summits.

    We take this idea a step further by extending a club to comprise sub-national states or provinces. This is especially relevant to the US, given its withdrawal from the Paris Agreement. Our study used 4 measures to predict the likelihood of involvement for governments at multiple levels.

    We identified a group of nine countries likely to be receptive to club membership (Figure 1). The EU appears as the preferred initiator of the club, given its high emissions and history of climate leadership. China could likely be convinced to join given its recent sharp rise in concern about local and global emissions.

    As US states have significant control over their economies, we evaluated the likelihoods of individual states joining the club. The results indicate that 10 of the 50 states are ‘very likely’ to do so, with a further 13 ‘moderately likely’ to do so. Further analysis (Figure 2) shows that 10 less motivated US states could be persuaded through strong export dependencies with the EU, Canada, Mexico and China, likely members of an initial climate club. In all, we find that states covering 69.9 % of US emissions may be amenable to club membership via either of these mechanisms.

    While a climate club evidently has to overcome political hurdles, the limitations of Paris and the urgency of effective climate solutions suggest the time is ripe for debating daring solutions.

  • Analysing the pledges of the Paris-Agreement (2019)

    van den Bergh, Jeroen (UAB)

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    Analysing the pledges of the Paris-Agreement

    The Paris Agreement takes a bottom-up approach to tackling climate change with countries submitting pledges in the form of nationally determined contributions (NDCs). Based on analysing such pledges, we classified them into 4 categories:

    1. Absolute emission reduction: for a target year in % terms relative to a historic base year, set by the country. The base year ranges from 1990 to 2014.

    2. Business-as-usual reduction (BAU): a % reduction in emissions relative to a no-policy scenario. BAU is defined by countries, causing large variance in emissions growth.

    3. Emission intensity reductions: a reduction in emission intensity per GDP relative to a base year. Effective emissions targets are then uncertain as they are dependent on future GDP growth.

    4. Projects absent of GHG-emission targets: no explicit GHG emission target but mention of projects intended to reduce emissions, like investment in renewable energy.

    These four categories cause a lack of consistency and transparency, which we correct for by normalisation. This involves calculating changes in emissions by 2030 – hence transforming categories 2-4 pledges to category 1 – using as the base year 2015. The result is shown in the figure. We find that pledges framed in terms of absolute emission reductions against historical base years generally produce the greatest ambition, with average emission reductions of 16% by 2030. Pledges defined as GDP intensity targets perform the worst with average emission increases of 61% by 2030.

    To illustrate, Russia, India and Pakistan all frame their NDCs in terms of % reductions: Russia relative to a base year, India to emissions per GDP, and Pakistan to a BAU scenario. This makes associated pledges hard to compare and causes a psychological effect of reducing ambition. Russia might have offered a more ambitious pledge if it was unable to frame its actual 13% emissions increase as a 25% decrease against a base year of choice.

    We advise to bar countries from presenting their pledges in a frame of own choice, or to let the UNFCCC normalise (updates of) pledges. Experiments demonstrate how aversion from shame is a powerful motivator of contributing to the commons.

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