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NEWS

December 2022 ESRFnews

The next ESRF User Meeting is set to be held on-site for the first time since the beginning of the COVID-19 pandemic. Taking place in Grenoble from 6 to 8 February 2023, the event is expected to strengthen relationships with international users. However, the plenary day will still be made accessible remotely online, and a final decision on the organisation will depend on the global health situation next year.

As usual, the first day is dedicated to tutorials, on topics ranging from the fundamental principles of techniques, to beamline control tools, to optimisation of data measurements and to science communication. On day two, the plenary speakers will be Kristina Djinović-Carugo of the European Molecular Biology Laboratory Grenoble in France, Paul Loubeyre and Sandrine Lyonnard of the French Alternative Energies and Atomic Energy Commission, and Kirsi Lorentz of the Cyprus Institute; there will also be directors reports, the annual presentation of the Young Scientist Award and a poster session. Day three will feature three user microsymposia: Environmental sciences: challenges and opportunities under a new era of synchrotron light ; Tomography at BM18 ; and Operando science of functional energy conversion, storage materials and devices .

According to the ESRF User Organisation Committee, a parallel theme will be how remote-access tools have been a game changer for new experimental approaches. This change of paradigm, mixing on-site and remote users, enhances the potential of the applications of the EBS, they write.

The deadline to be registered for on-site attendance, and to be featured in the conference booklet as a participant or for a poster is 16 January, while the deadline to submit a poster for the Best Poster Prize contest is 29 January.

User Meeting back on-site

ID19 exposes oldest heart The ESRF has helped to image the oldest ever heart of a vertebrate. Fossilised in limestone, the organ belongs to an ancient jawed fish known as a placoderm, and is visible alongside a separate fossilised stomach, intestine and liver. Kate Trinajstic of Curtin University

in Bentley, Western Australia, and colleagues studied nine fossil samples collected in the Gogo Formation, a sedimentary deposit in Western Australia, in the region of 400 million years old. Of these, four were scanned via propagation phase-contrast X-ray microtomography at the ESRF s ID19 beamline; another was scanned with a thermal-neutron imaging instrument at the Australian Nuclear Science and Technology Organization. The scans revealed, for the first time, the 3D model of a complex, S-shaped heart made up of two chambers an advanced feature for such early vertebrates, showing how the fish s head and neck had begun to evolve to

accommodate jaws. However, the fish had no lungs, refuting the hypothesis that lungs are ancestral in jawed vertebrates (Science 377 6612). Evolution is often thought of

as a series of small steps, but these ancient fossils suggest there was a larger leap between jawless and jawed vertebrates, says Trinajstic. These fish literally have their hearts in their mouths and under their gills, just like sharks today.

New results on RNA regulation give insight into how a cell can discard disruptive RNA transcripts that lead to diseases. They have been produced in a collaboration between the Institut de Biologie Structurale (IBS), the European Molecular Biology Laboratory and the ESRF within the Partnership for Structural Biology (PSB). Ribonucleic acid, or RNA, is an

essential molecule for the coding, decoding, regulation and expression of genes. It is being synthesised constantly in eukaryotic nuclei within cells, but aberrant RNA gene transcripts can lead to diseases if the cells do not recognise them. That requires specialised RNA-targeting complexes, which deliver the unwanted transcripts to molecular machinery known as the RNA exosome for degradation. The process is regulated by the yeast MTREC protein complex and its human counterpart, PAXT. Now, the IBS-led team has, for

the first time, determined the interactions that MTREC forms with the individual sub-modules, and how these modules function. The ESRF s molecular biology lab performed an assay to see how the sub-modules interact with one another, while

Fish found in the Gogo Formation of Australia were fearsome predators.

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RNA degradati on unpicked

the ID30A-3 beamline performed crystallographic analysis to solve the structure of one of the most interesting complexes, called Ars2-Red1. The fact that structural features occurred in both the yeast and the human complex suggested that they use the same mechanism to control RNA metabolism (Nat. Commun. 13 4969). This shows how working

together within the PSB on campus can lead to revealing results, says IBS team leader Jan Kadlec.

Crystal structure of the Ars2-Red1 complex.

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