Manuscript Format and Files

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PNAS Author Center

When a revision is submitted to PNAS, all files must be in production-ready format; extensive edits will not be allowed at proofs. Text files should be provided in Word, RTF, or LaTeX format. Tables should be included at the end of the manuscript file. Word and RTF manuscript files should not contain any embedded figures or schemes; these should be uploaded individually in TIFF, EPS, PPT, or high-resolution PDF. Supporting Information can include datasets and movies in addition to a single SI Appendix PDF. Please see the Supporting Information section for details.

Please supply high-resolution files whenever possible. Resolution of at least 1200 dpi is needed for all line art, 600 dpi for images that combine line art with photographs/halftones, and 300 dpi for color or grayscale photographic images. Please review the PNAS Digital Art Guidelines. High-resolution files are not required for initial submissions.

Manuscript Order

Many authors find it useful to organize their manuscript sections as follows: title page, abstract, significance statement, introduction, results, discussion, materials and methods, acknowledgments, references, and figure legends. If authors present information clearly and concisely, other variations to this format are allowed. Number all manuscript pages starting with the title page. Templates for formatting production-ready manuscripts are available for both Word and LaTeX submissions.

Title Page

Please include the following information on the title page:

• Classification: Select a major (Physical, Social, or Biological Sciences) and a minor category from the following. Dual classifications are permitted between major categories and in exceptional cases, subject to Editorial Board approval, within a major category.
   
• PHYSICAL SCIENCES: Applied Mathematics; Applied Physical Sciences; Astronomy; Biophysics and Computational Biology; Chemistry; Computer Sciences; Earth, Atmospheric, and Planetary Sciences; Engineering; Environmental Sciences; Mathematics; Physics; Statistics; and Sustainability Science.
   
• SOCIAL SCIENCES: Anthropology; Economic Sciences; Environmental Sciences; Political Sciences; Psychological and Cognitive Sciences; Social Sciences; and Sustainability Science.
   
• BIOLOGICAL SCIENCES: Agricultural Sciences; Anthropology; Applied Biological Sciences; Biochemistry; Biophysics and Computational Biology; Cell Biology; Developmental Biology; Ecology; Environmental Sciences; Evolution; Genetics; Immunology and Inflammation; Medical Sciences; Microbiology; Neuroscience; Pharmacology; Physiology; Plant Biology; Population Biology; Psychological and Cognitive Sciences; Sustainability Science; and Systems Biology.
   
• Title: Titles should be no more than 3 typeset lines (generally 135 characters including spaces) and should be comprehensible to a broad scientific audience. The organism studied should be included.
   
• Author Line: List the full names of all authors in the order intended for publication. Include asterisks to designate co-corresponding authors and superscripts to indicate equal contributions.
   
• Author Affiliation: Include department, institution, and complete address, with the ZIP/postal code, for each author. Use superscripts to match authors with institutions. Multiple affiliations are allowed. Authors are strongly encouraged to supply their ORCID identifier.
   
• Corresponding Author: The name, complete address, phone number, and email address of the author or authors to whom correspondence and proofs should be sent. Email addresses will be published in the article footnotes.
   
• Keywords: Keywords are listed below the article abstract. At least 3 keywords are required at submission.

Abstract

Provide an abstract of no more than 250 words on page 2 of the manuscript. Abstracts should explain to the general reader the major contributions of the article. References in the abstract must be cited in full within the abstract itself and cited in the text.

Significance Statement

Authors must submit a statement of no more than 120 words about the significance of their research paper written at a level understandable to an undergraduate-educated scientist outside their field of specialty. The primary goal of the Significance Statement is to explain the relevance of the work in broad context to a broad readership. Significance statements are not required for Brief Reports.

Text

Describe procedures in sufficient detail so that the work can be repeated. Methods must be presented after results and discussion. Follow the spelling and usage given in Webster's Third New International Dictionary or the Random House Dictionary of the English Language. Avoid laboratory jargon. Correct chemical names should be given, and strains of organisms should be specified. Trade names should be identified by an initial capital letter with the remainder of the name lowercase. Names of suppliers of uncommon reagents or instruments should be provided. Use Système International units and symbols whenever possible. Statements of novelty and priority are not permitted in the text.

• Language Editing Services: Prior to submission, authors who believe their manuscripts would benefit from professional editing are encouraged to use an editing service (see list here). PNAS does not take responsibility for or endorse these services, and their use has no bearing on acceptance of a manuscript for publication.
   
• Use of URLs in Text: As a publisher, PNAS must be able to archive the data essential to a published article. Where such archiving is not possible, deposition of data in public databases, such as GenBank, ArrayExpress, Protein Data Bank, Unidata, and others outlined in the Information for Authors, is acceptable. Only links to websites that are permanent public repositories, such as self-perpetuating online resources funded by government, academia, and industry, are permitted. Links to an author's personal web page are not acceptable.
   
• Gene Nomenclature: Prior to submission, authors should consult Genecards, MGI Nomenclature page, HUGO Gene Nomenclature Committee, or equivalent resources to ensure standardized nomenclature is used for species-specific gene and protein names. For proposed gene names, please submit the gene symbols to the appropriate nomenclature committee as these must be deposited and approved before publication of the article.
   
• Abbreviations: Abbreviations should be accessible to a broad scientific audience; abbreviations that are specific to a particular field should be defined at first mention in the text.
   
• Nomenclature and Style: Use international standards on nomenclature. PNAS uses Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers (8th edition, 2014) as the primary style guide.
   
• Equations: Equations need to be editable; these should be created with either Microsoft Equation Editor or MathType. Images of equations are not acceptable.

Footnotes

PNAS distinguishes author affiliations and footnotes from in-text footnotes by assigning a different set of footnote symbols to each type. Superscript lowercase letters separated by commas (no spaces) are used for author affiliations. Superscript numerals separated by commas (no spaces) are used for author footnotes. In-text footnotes should be preceded by a footnote symbol, used in the order *, †, ‡, §, ¶, #, ||,**, ††, ‡‡, §§, ¶¶, ##.

Acknowledgments

List acknowledgments and funding sources; all abbreviations should be spelled out. PNAS collaborates with FundRef to use a standard taxonomy of funder names. Dedications are rarely allowed.

References

References must be in PNAS style (revised 4/2019). For references to in-press articles, please confirm with the cited journal that the article is in press and include a DOI number and online publication date. Unpublished abstracts of papers presented at meetings or references to "data not shown" are not permitted. References should be cited in numerical order as they appear in text, and all references cited in the main text should be included in the main manuscript file. Include a separate citation list for references cited in the SI. Because tables and figures will be inserted in the text where first cited, references in these sections should be numbered accordingly. Include the full title for each cited article. All authors may be named in the citation for initial submissions. For revisions or final submissions, if there are more than 5 authors, list the first author’s name followed by et al. Provide volume numbers for journal articles as applicable; provide DOI numbers if volume numbers are not available. Provide inclusive page ranges for journal articles and book chapters. Provide date of access for online sources.

Journal articles are cited as follows:

10. J.-M. Neuhaus, L. Sticher, F. Meins, Jr., T. Boller, A short C-terminal sequence is necessary and sufficient for the targeting of chitinases to the plant vacuole. Proc. Natl. Acad. Sci. U.S.A. 88, 10362–10366 (1991).

Cite research datasets in the references and list the authors, title, publisher (repository name), identifier (DOI in URL format), and date of deposition as follows:

12. E. van Sebille, M. Doblin, Data from “Drift in ocean currents impacts intergenerational microbial exposure to temperature.” Figshare. Available at https://dx.doi.org/10.6084/m9.figshare.3178534.v2. Deposited 15 April 2016.

Use MEDLINE/PubMed abbreviations of journal titles or use the full journal title for any journals not indexed in MEDLINE.

Articles or chapters in books are cited as follows:

14. A. V. S. Hill, “HLA associations with malaria in Africa: Some implications for MHC evolution” in Molecular Evolution of the Major Histocompatibility Complex, J. Klein, D. Klein, Eds. (Springer, 1991), pp. 403–420.

Preprints are cited as follows with a DOI or preprint ID number, and the date of posting:

15. H. Luetkens et al., Electronic phase diagram of the LaO1–xFxFeAs superconductor. arXiv:0806.35331 (21 June 2008).

Figure Legends

Provide these separately from figures, after the references in the manuscript. For figures with multiple panels, the first sentence of the legend should be a brief overview of the entire figure; each panel must be explicitly referenced and described at least once in the figure legend. Graphs should include clearly labeled error bars described in the figure legend. Authors must state whether a number that follows the ± sign is a standard error (SEM) or a standard deviation (SD). The P value, magnification, or scale bar information should be provided when applicable. The number of independent data points (N) represented in a graph must be indicated in the legend. Numerical axes on graphs should go to 0, except for log axes.

Digital Figures

High-resolution figure source files are required for revised and Contributed submissions. Resolution of at least 300 dpi for all figures is recommended. EPS, high-resolution PDF, and PowerPoint are preferred formats for figures that will be used in the main manuscript. Authors may submit PRC or U3D files for 3D images; these must be accompanied by 2D representations in TIFF, EPS, or high-resolution PDF format. Color images should be in RGB (red, green, blue) mode.

Images must be provided at final size, approximately 9 cm x 6 cm for a small figure, approximately 11 cm x 11 cm for a medium figure, and approximately 18 cm x 22 cm for a large figure. While authors may size figures conservatively to save page space, PNAS reserves the right to set the final publication size, and you may be asked to shorten your manuscript if it exceeds the stated length requirements. Numbers, letters, and symbols should be no smaller than 6 points (2 mm) and no larger than 12 points (6 mm) after reduction and must be consistent within figures. Composite figures must be preassembled. Figures must be submitted as separate files, not embedded in the manuscript text. See the PNAS Digital Art Guidelines.

Tables

Each table should have a brief title above the table. Table footnotes should be below the table. Tables should be included at the end of the manuscript text, in portrait orientation. Landscape/broadside tables are not allowed. The maximum allowable size of an individual table is one full article page, approximately 70 rows. Publication-ready formats include Word and LaTeX. Avoid multipart tables (Table 1A, Table 1B).

Supporting Information

The main text of the paper must stand on its own without the Supporting Information. Refer to the SI Appendix in the manuscript at an appropriate point in the text. Number supporting figures and tables starting with S1, S2, etc. References should be cited in numerical order as they appear in the SI; do not cite main-text references in the SI and vice versa.

Authors who place detailed materials and methods in an SI Appendix must provide sufficient detail in the main-text methods to enable a reader to follow the logic of the procedures and results and also must reference the SI methods. If a paper is fundamentally a study of a new method or technique, then the methods must be described completely in the main text.

SI Appendix: PNAS publishes SI as a noncomposed PDF file, as the authors have provided it. Authors should submit SI as a single SI Appendix PDF file, combining all text, figures, tables, movie legends, and SI references. We recommend using or following the PNAS SI template, which can be downloaded in Word or LaTeX. Please note that this file will not be copyedited, and should be provided in its final form. Additional information on how to prepare your SI Appendix is included in the SI templates.

Datasets: Supply Excel (.xls or .xlsx), RTF, PDF, CSV, or TXT files. Datasets will be published in raw format and will not be edited or composed.

Movies: Supply Audio Video Interleave (.avi), Quicktime (.mov), Windows Media (.wmv), animated GIF (.gif), or MPEG files, and submit a brief legend for each movie in the SI Appendix. All movies should be submitted at the desired reproduction size and length. Movies should be no more than 10 MB in size.

Journal Cover Figures

Authors are invited to submit scientifically interesting and visually arresting cover images (see our archive). Illustrations need not appear in the article but should be representative of the work. Images should be original, and authors grant PNAS a license to publish. Include a brief lay-language caption (50–60 words) and credit information (e.g., Image courtesy of...). Images should be 21 cm wide by 22.5 cm high. Files should be EPS or TIFF and should be in RGB color mode. Cover figure files may be submitted online when the paper is submitted or may be sent to PNASCovers@nas.edu; contact PNAS for instructions on submitting large files. The deadline for cover submissions is when proof corrections are returned. Submissions provided outside the online submission system should include the manuscript number, author name, phone, and email.

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