WASHINGTON, DC – The Editorial Board of the Proceedings of the National Academy of Sciences (PNAS) has selected six papers published by PNAS in 2021 to receive the Cozzarelli Prize, an award that recognizes outstanding contributions to the scientific disciplines represented by the National Academy of Sciences (NAS). Papers were chosen from more than 3,500 research articles that appeared in the journal last year and represent the six broadly defined classes under which the NAS is organized. Additionally, the Editorial Board has recognized six papers—one in each class—as finalists for the 2021 Cozzarelli Prize.

The annual Cozzarelli Prize acknowledges papers that reflect scientific excellence and originality. The award was established in 2005 as the Paper of the Year Prize and was renamed in 2007 to honor late PNAS Editor-in-Chief Nicholas R. Cozzarelli. The 2021 awardees will be recognized at an awards ceremony during the NAS Annual Meeting in April 2022.

2021 Cozzarelli Prize Recipients

Class I: Physical and Mathematical Sciences


Chromatophores efficiently promote light-driven ATP synthesis and DNA transcription inside hybrid multicompartment artificial cells

Emiliano Altamura, Paola Albanese, Roberto Marotta, Francesco Milano, Michele Fiore, Massimo Trotta, Pasquale Stano, and Fabio Mavelli

A major goal of synthetic biology is the construction of artificial protocells, which are self-organized lipid structures proposed to be precursors to cellular life. One challenge facing artificial protocells is how to autonomously generate energy to power internal processes. The authors of this study entrapped structures called chromatophores from purple nonsulfur bacteria (Rhodobacter sphaeroides) in giant lipid vesicles along with the necessary components for synthesis of ATP, the cellular energy currency, and for gene expression. The chromatophores acted as nanosized photosynthetic organelles, using light to synthesize ATP. In turn, the ATP fueled gene expression within the cells. The results show how bacterial chromatophores can fuel artificial cells for both biotechnological applications and studies on the origin of life on Earth.



Direct visualization of bottlebrush polymer conformations in the solid state

Jonathan M. Chan, Avram C. Kordon, Ruimeng Zhang, and Muzhou Wang


Class II: Biological Sciences


Recombination-independent recognition of DNA homology for meiotic silencing in Neurospora crassa

Nicholas Rhoades, Tinh-Suong Nguyen, Guillaume Witz, Germano Cecere, Thomas Hammond, Alexey K. Mazur, and Eugene Gladyshev

The pairing of homologous chromosomes is a key step in the production of sex cells during meiosis, but the underlying mechanisms remain unclear. The authors characterized a mechanism for chromosome homology recognition by exploring the genetics of a process called meiotic silencing by unpaired DNA in the fungus Neurospora crassa. During this process, double-stranded DNAs (ds-DNAs) are recognized as pairable based on specific patterns of interspersed homology. The authors’ biophysical model of direct pairing between ds-DNA molecules suggests that the process is efficient and may be involved in other phenomena featuring interactions between intact, homologous DNA molecules. The results identify a novel mechanism for homology recognition during meiosis—an essential process for ensuring fertility and preventing birth defects.



Nuclear envelope budding is a response to cellular stress

Dimitra Panagaki, Jacob T. Croft, Katharina Keuenhof, Lisa Larsson Berglund, Stefanie Andersson, Verena Kohler, Sabrina Büttner, Markus J. Tamás, Thomas Nyström, Richard Neutze, and Johanna L. Höög


Class III: Engineering and Applied Sciences


Optical computation of a spin glass dynamics with tunable complexity

M. Leonetti, E. Hörmann, L. Leuzzi, G. Parisi, and G. Ruocco

Spin glasses are complex disordered systems that serve as models for investigating phenomena as diverse as brain function, random lasers, and quantum dynamics. However, calculating the energy of the equilibrium states of spin glasses is challenging. The authors of this study fashioned an optical method to calculate the energy of a spin glass state. The authors represented the system’s state using an adaptive-optics mirror, which separates a laser input into multiple segments, and read the energy of the spin glass state by collecting the intensities of the scattered laser segments. The authors’ optical method is advantageous over digital algorithms for parallel energy calculation for large-scale disordered systems. The findings carry potential implications for improving neural networks for sound recognition, image reconstruction, and high-definition fiber endoscopy in medical diagnosis.



Stretchable origami robotic arm with omnidirectional bending and twisting

Shuai Wu, Qiji Ze, Jize Dai, Nupur Udipi, Glaucio H. Paulino, and Ruike Zhao


Class IV: Biomedical Sciences


Lipopeptide-mediated bacterial interaction enables cooperative predator defense

Shuaibing Zhang, Ruchira Mukherji, Somak Chowdhury, Lisa Reimer, and Pierre Stallforth

Communities of microbes can cooperate to defend against predators. In this study, the authors found that two unrelated bacterial strains, Pseudomonas and Paenibacillus, each susceptible to predation by amoebae, exchanged natural products to defeat predators when the strains were grown together. When exposed to predatory amoebae, one strain produced a molecule called syringafactin, which induced the other strain to produce enzymes called peptidases. The peptidases broke down syringafactin into fragments that proved toxic to the amoebae. This study shows how microbes work together to guard against predators and suggests that microbial interactions may be a source of novel and potent bioactive compounds.



The missing enzymatic link in syntrophic methane formation from fatty acids

Michael Agne, Sebastian Estelmann, Carola S. Seelmann, Johannes Kung, Dennis Wilkens, Hans-Georg Koch, Chris van der Does, Sonja V. Albers, Christoph von Ballmoos, Jörg Simon, and Matthias Boll


Class V: Behavioral and Social Sciences


Learning loss due to school closures during the COVID-19 pandemic

Per Engzell, Arun Frey, and Mark D. Verhagen

The effects of school closures during the COVID-19 pandemic on student learning are unclear. Using a dataset of exam scores of students aged 8–11 years that covered 15% of all primary schools in the Netherlands, this study examined the effects of school closures on learning. Analysis of exam scores before and after an 8-week nationwide lockdown in 2020, when face-to-face instruction was suspended, revealed a learning loss of 3 percentile points—equivalent to one-fifth of a typical school year—compared with the same period in the preceding 3 years. The loss was exacerbated among students from less well-educated homes, indicating the closures’ uneven demographic toll on student learning.



Native American fire management at an ancient wildland–urban interface in the Southwest United States

Christopher I. Roos, Thomas W. Swetnam, T. J. Ferguson, Matthew J. Liebmann, Rachel A. Loehman, John R. Welch, Ellis Q. Margolis, Christopher H. Guiterman, William C. Hockaday, Michael J. Aiuvalasit, Jenna Battillo, Joshua Farella, and Christopher A. Kiahtipes


Class VI: Applied Biological, Agricultural, and Environmental Sciences


Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution

Guntur V. Subbarao, Masahiro Kishii, Adrian Bozal-Leorri, Ivan Ortiz-Monasterio, Xiang Gao, Maria Itria Ibba, Hannes Karwat, M. B. Gonzalez-Moro, Carmen Gonzalez-Murua, Tadashi Yoshihashi, Satoshi Tobita, Victor Kommerell, Hans-Joachim Braun, and Masa Iwanaga

Nearly one-fifth of nitrogen fertilizers produced in factories worldwide is consumed by wheat farming.  Nitrification, a process triggered by fertilizer use, can harm soil fertility and ecosystems. Although synthetic inhibitors can reduce soil nitrification, their use is limited by high cost and low efficacy in tropical environments. The authors uncovered a genomic segment in wild grass (Leymus racemosus) encoding the production of biological nitrification inhibitors from plant roots. Transferring the segment into high-yielding wheat varieties nearly doubled their ability to block nitrification. The transfer also increased nitrogen uptake and grain yield in some varieties. Genetically endowing wheat with the ability to block nitrification might help combat nitrogen pollution without affecting yield or coveted agronomic attributes.



Deep learning for early warning signals of tipping points

Thomas M. Bury, R. I. Sujith, Induja Pavithran, Marten Scheffer, Timothy M. Lenton, Madhur Anand, and Chris T. Bauch


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Prashant Nair
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Proceedings of the National Academy of Sciences (PNAS)