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 24 publications 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: 2017
  • Diet, Environment and Respiratory Irritants in the Lower Palaeolithic (2015)

    Hardy, Karen (UAB)

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    Reconstructing detailed aspects of the lives of Lower Palaeolithic hominins, who lived during the Middle Pleistocene, is challenging due to the restricted nature of the surviving evidence, predominantly animal bones and stone tools. But hominins, just like humans, needed plant foods in order to survive and reproduce. The site of Qesem Cave, Israel, which was inhabited between 420,000-200,000 years ago, has evidence for a wealth of innovative features including the earliest clear evidence worldwide for controlled use of fire.  Analysis of remains embedded in samples of dental calculus from the hominins who lived here found evidence for a range of inhaled and ingested materials. These finds offer an insight into the environment in and around the cave, as inhaled pollen grains from pine trees indicate a forested environment, while micro-charcoal suggests smoke inhalation may have been a problem inside the cave.  Plant fibres and a phytolith may be evidence of oral hygiene activities or of using the teeth to work raw materials. Starch granules and chemical compounds provide a direct link to ingested plant food items, most specifically, the presence of plants containing the essential linoleic and linolenic polyunsaturated fatty acids. Together, these results represent a significant breakthrough towards a better understanding of Middle Pleistocene dietary breadth and highlight some of the challenges facing the adoption of the habitual use of fire for cooking by the Qesem Cave hominins, as well as offering new information on the paleoenvironment surrounding the cave, and new insights into palaeolithic ecological knowledge and technological adaptability.

  • ‘DNA spellchecker’ means that our genes aren’t all equally likely to mutate and cause cancer (2015)

    Lehner, Ben (CRG)

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    Copying the large book that it is our genome without mistakes every time a cell divides is a difficult job. Luckily, our cells are well-equipped to proof-read and repair DNA mistakes. This study showed that mistakes in different parts of our genome are not equally well corrected.  This means that some of our genes are more likely to mutate during our lifetimes and so contribute to disease than others.

    The scientists analysed 17 million ‘single nucleotide variants’ – mutations in just one nucleotide (letter) of the DNA sequence – by examining 650 human tumours from different tissues. These were ‘somatic’ mutations, meaning they are not inherited from parents or passed down to children, but accumulate in our bodies as we age. Such somatic mutations are the main cause of cancer. Many result from mutagens, such as tobacco smoke or ultraviolet radiation, and others come from naturally occurring mistakes in copying DNA as our tissues renew.

    Ben Lehner and his team had previously described that somatic mutations are much more likely in some parts of the human genome, thus damaging genes that may cause cancer. In a new paper they show that this is because genetic mistakes are better repaired in some parts of the genome than in others. This variation was generated by a particular DNA repair mechanism called “mismatch repair” – a sort of a spellchecker that helps fix the errors in the genome after copying. The data showed that the efficiency of this ‘DNA spellchecker’ varies depending on the region of the genome, with some parts of chromosomes getting more attention than others. The study illustrates how data from medical sequencing projects can answer basic questions about how cells work.

  • Nanopaper as an Optical Sensing Platform (2015)

    Merkoçi, Arben (ICN2)

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    Cellulose is simple, naturally abundant and low cost. However, cellulose fibres ranging at the nanoscale exhibit extraordinary properties such as flexibility, high crystallinity, biodegradability and optical transparency. The nanomaterial can be extracted from plant cellulose pulp or synthetized by non-pathogenic bacteria. Nanocellulose is under active research to develop a myriad of applications including filtration, wound dressing, pollution removal approaches or flexible and transparent electronics, whereas it has been scarcely explored for optical (bio)sensing applications.

    The team led by Prof. Merkoçi seeks to design, fabricate, and test simple, disposable and versatile sensing platforms based on this material. They designed different bacterial cellulose nanopaper based optical sensing platforms. In the article, it is described how the material can be tuned to exhibit plasmonic or photoluminescent properties that can be exploited for sensing applications. Specifically, they have prepared two types of plasmonic nanopaper and two types of photoluminescent nanopaper using different optically active nanomaterials.

    The researchers took advantage of the optical transparency, porosity, hydrophilicity, and amenability to chemical modification of the material. The bacterial cellulose employed throughout this research was obtained using a bottom-up approach and it is shown that it can be easily turned into useful devices for sensing applications using wax printing or simple punch tools. They also demonstrate how these novel sensing platforms can be modulated to detect biologically relevant analytes such as cyanide and pathogens.

    According to the authors, this class of platforms will prove valuable for displaying analytical information in diverse fields such as diagnostics, environmental monitoring and food safety. Moreover, since bacterial cellulose is flexible, lightweight, biocompatible and biodegradable, the proposed composites could be used as wearable optical sensors and could even be integrated into novel theranostic devices. Paper-based sensors might be exploited in medicine, detection of explosives or hazardous compounds and environmental studies.

  • Closing the Door on Einstein and Bohr’s Quantum Debate (2015)

    Mitchell, Morgan W. (ICFO)
    Pruneri, Valerio (ICFO)

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    Quantum mechanics makes extraordinarily accurate predictions, but has internal workings so counter-intuitive that many refuse to believe they represent reality. Among these non-believers was Albert Einstein, who, starting in 1927, carried on an extended debate with Niels Bohr, a towering figure in quantum theory. In 1935 Einstein argued for the creation of a theory that was compatible with both the Theory of Relativity, in which the speed of light is a fundamental limit, and with realism, the idea that our observations reflect a reality independent of ourselves. This position, now called “local realism,” directly opposed Bohr's arguments for the uncertainty principle.  The debate between these two giants of physics was never settled. In 1964, CERN researcher John Stuart Bell showed that an experiment could resolve this seemingly philosophical question.  Bell analyzed the following scenario: pairs of particles are sent to widely-separated measurement stations, where one property of each particle is measured.  The measurements are chosen randomly and performed simultaneously.  If the particles show sufficiently well-correlated behaviour, Bell proved, something in local realism must be wrong: Either the particle properties had no prior existence, or particles can communicate with each other faster than light (or both).  Starting in 1972, a sequence of experiments have approximated Bell's scenario with increasing sophistication.  Until this year, however, all experiments contained weaknesses, or “loopholes,” allowing alternate explanations.  For example: not performing the measurements fast enough, not measuring enough of the particles, or not choosing sufficiently randomly.  This year, three experiments: at TU Delft, IQOQI (Vienna), and NIST (USA), succeeded in simultaneously closing all of the closable loopholes, and in doing so solidly rejected local realism. 

    This work was the result of three collaborations:  TU Delft - ICREA - ICFO - Element 6, IQOQI - U. Vienna - MQP - Linköpings U. - ICREA - ICFO - PTB - NIST, and NIST - IQC - U. Illinois - U. Moncton - JQI - JPL - ICREA - ICFO - CIAR

  • New Fossil suggests we had a Gibbon-like Early Ancestor (2015)

    Moyà Solà, Salvador (ICP)

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    The evolutionary history of extant gibbons (Hylobatidae, Hominoidea, Primates) or Lesser Apes, is probably one of the most enigmatic problems in primate evolution. The absence of fossil evidence to show when and where the gibbon lineage emerged is the major difficulty. However, recent fieldwork in the extraordinary Catalan Miocene fossil record -the most complete of the Eurasian continent in respect to hominoid evolution- provided a partial skeleton composed of 70 specimens in one of the sites of the stratigraphic series of Abocador de Can Mata (els Hostalets de Pierola, Barcelona). These include most of the skull and dentition, as well as a considerable portion of the left arm, including several elements of the elbow and wrist joints. The analysis of the new finding, allowed the description of a new genus and species of extinct hominoid, Pliobates cataloniae. They belong to an ape of similar size to that of the smallest living gibbons (4 to 5 kg), which lived 11.6 million years ago. Pliobates shows, for the first time in a fossil primate of this size, a set of characteristic features of extant hominoids, presumably inherited from their last common ancestor, which probably lived in Africa several million years before Pliobates.

    This find radically changes the hitherto accepted morphotype of the hylobatid-hominid ancestor and provides very solid clues about the origin of extant gibbons. All the small-bodied (5 to 15 kg) fossil anthropoids found before Pliobates are too primitive to be closely related to extant hominoids. Although Pliobates retains some primitive characters, the arm anatomy and, in particular, the joint between the humerus and radius as well as the wrist bones already possess the basic design of living hominoids. A phylogenetic analysis, based on more than 300 characters, very consistently places Pliobates as the stem hominoid closest to the divergence between lesser and great apes, and suggests that the last common ancestor of extant hominoids might have been more similar to living gibbons than to great apes. Furthermore, the skull and some parts of the postcranial skeleton show some features that are exclusive of extant gibbons.

  • CO2 sequestration in the deep Pacific Ocean during glacial times (2015)

    Pelejero Bou, Carles (CSIC - ICM)

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    The cause of the characteristic variability in atmospheric CO2 over glacial-interglacial timescales has been under debate since its discovery in the 1980s. Initially based on the study of Antarctica ice cores, an intriguing parallelism was found between atmospheric CO2 and global temperature, with high CO2 levels during warm interglacial periods, and low CO2 concentrations during cold glacial times. Even though the oceans have often been put forward as the main responsible for this parallelism, their role in sequestering and releasing CO2 and the mechanisms behind this still remains an open question. In this study, we analyzed the evolution of the ventilation of the Eastern Equatorial Pacific waters over the past 25,000 years aiming at detecting the existence of old water masses which could explain a possible CO2 sequestration in the deep ocean. To this end, we analyzed the radiocarbon (14C) preserved in the shells of benthic and planktonic foraminifera fossils accumulated in a deep sea sediment core retrieved in this area. These data demonstrated the existence of a mass of deep water that, during glacial times, was about 1,300 years older than the same water mass today. With the start of the deglaciation, the radiocarbon signal indicated a reactivation of the ocean circulation, coinciding with the increase in atmospheric CO2 documented in ice cores. Altogether, these results support the hypothesis that the deep oceans, particularly the Pacific Ocean, stored vast amounts of CO2 during the last glacial period, which was released during the deglaciation. These results lend support to the important role of the deep ocean and ocean ventilation in regulating the atmospheric concentration of CO2 at glacial/interglacial timescales. Over the last decade, the oceans have been absorbing approximately 26% of the anthropogenic emissions of CO2. The oceans have been a key element in controlling atmospheric CO2 levels in the past and at present, and they will certainly also play a very significant role in the future, a role that will be constrained more accurately with data from paleoreconstructions such as this one.

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