Abstract
Scientists routinely use images to display data. Readers often examine figures first; therefore, it is important that figures are accessible to a broad audience. Many resources discuss fraudulent image manipulation and technical specifications for image acquisition; however, data on the legibility and interpretability of images are scarce. We systematically examined these factors in non-blot images published in the top 15 journals in three fields; plant sciences, cell biology and physiology. Common problems included missing scale bars, misplaced or poorly marked insets, images or labels that were not accessible to colorblind readers, and insufficient explanations of colors, labels, annotations, or the species and tissue or object depicted in the image. Papers that met all good practice criteria examined for all image-based figures were uncommon (physiology 16%, cell biology 12%, plant sciences 2%). We present detailed descriptions and visual examples to help scientists avoid common pitfalls when publishing images. Our recommendations address image magnification, scale information, insets, annotation, and color and may encourage discussion about quality standards for bioimage publishing.
Introduction
Images are often used to share scientific data, providing the visual evidence needed to turn concepts and hypotheses into observable findings. An analysis of 8 million images from more than 650,000 papers deposited in PubMed Central revealed that 22.7% of figures were “photographs”, a category that included microscopy images, diagnostic images, radiology images and fluorescence images.1 Cell biology was one of the most visually intensive fields, with publications containing an average of approximately 0.8 photographs per page.1 Plant sciences papers included approximately 0.5 photographs per page.1
While there are many resources on fraudulent image manipulation and technical requirements for image acquisition and publishing,2-4 data examining the quality of reporting and ease of interpretation for image-based figures are scarce. Recent evidence suggests that important methodological details about image acquisition are often missing.5 Researchers generally receive little or no training in designing figures; yet many scientists and editors report that figures and tables are one of the first elements that they examine when reading a paper.6, 7 When scientists and journals share papers on social media, posts often include figures to attract interest. The PubMed search engine caters to scientists’ desire to see the data by presenting thumbnail images of all figures in the paper just below the abstract.8 Readers can click on each image to examine the figure, without ever accessing the paper or seeing the introduction or methods. EMBO’s Source Data tool (RRID:SCR_015018) allows scientists and publishers to share or explore figures, as well as the underlying data, in a findable and machine readable fashion.9
Image-based figures in publications are generally intended for a wide audience. This may include scientists in the same or related fields, editors, patients, educators and grants officers. General recommendations emphasize that authors should design figures for their audience rather than themselves, and that figures should be self-explanatory.7 Despite this, figures in papers outside one’s immediate area of expertise are often difficult to interpret, marking a missed opportunity to make the research accessible to a wide audience. Stringent quality standards would also make image data more reproducible. A recent study of fMRI image data, for example, revealed that incomplete documentation and presentation of brain images led to non-reproducible results.10, 11
Here, we examined the quality of reporting and accessibility of image-based figures among papers published in top journals in plant sciences, cell biology and physiology. Factors assessed include the use of scale bars, explanations of symbols and labels, clear and accurate inset markings, and transparent reporting of the object or species and tissue shown in the figure. We also examined whether images and labels were accessible to readers with the most common form of color blindness.12 Based on our results, we provide targeted recommendations about how scientists can create informative image-based figures that are accessible to a broad audience. These recommendations may also be used to establish quality standards for images deposited in emerging image data repositories.
Using a science of science approach to investigate current practices
This study was conducted as part of a participant-guided learn-by-doing course, in which eLife Community Ambassadors from around the world worked together to design, complete, and publish a meta-research study. Participants in the 2018 Ambassadors program designed the study, developed screening and abstraction protocols, and screened papers to identify eligible articles (HJ, BA, SJB, VB, LHH, VI, SS, EMW). Participants in the 2019 Ambassadors program refined the data abstraction protocol, completed data abstraction and analysis, and prepared the figures and manuscript (AA, SA, TLA, IF, MAG, HL, SYM, MO, AV, KW, HJ, TLW).
To investigate current practices in image publishing, we selected three diverse fields of biology to increase generalizability. For each field, we examined papers published in April 2018 in the top 15 journals, which publish original research (Table S1, Table S2, Table S3). All full-length original research articles that contained at least one photograph, microphotograph, electron microscopy image, or clinical image (MRI, ultrasound, X-ray, etc.) were included in the analysis (Figure S1). Blots and computer-generated images were excluded, as some of the criteria assessed do not apply to these types of images. Two independent reviewers assessed each paper, according to the detailed data abstraction protocol (see methods and information deposited on the Open Science Framework (RRID:SCR_017419) at https://osf.io/b5296/?view_only=9166dc4099504a9f8635add45ed70b0d).13
Results
First, we confirmed that images are common in the three biology subfields analyzed. More than half of the papers in the sample contained images (plant science: 68%, cell biology: 72%, physiology: 55%). Among papers that included images, microscopy images were very common in all three fields (61 to 88%, Figure 1). Photographs were very common in plant sciences (86%), but less widespread in cell biology (38%) and physiology (17%). Electron microscopy images were less common in all three fields (11 to 19%). Clinical images, such as X-rays, MRI or ultrasound, and other types of images were rare (2 to 9%).
Scale information is essential to interpret biological images. Approximately half of papers in physiology (49%) and cell biology (55%), and 28% of plant science papers provided scale bars with dimensions (in the figure or legend) for all images in the paper (Figure 1b). Approximately one-third of papers in each field contained incomplete scale information, such as reporting magnification or presenting scale information for a subset of images. Twenty-four percent of physiology papers, 10% of cell biology papers, and 29% of plant sciences papers contained no scale information on any image.
Some publications use insets to show the same image at two different scales (cell biology papers: 40%, physiology: 17%, plant sciences: 12%). In this case, the authors should indicate the position of the high-magnification inset in the low-magnification image. The majority of papers in all three fields clearly and accurately marked the location of all insets (53 to 70%), however one-fifth of papers appeared to have marked the location of at least one inset incorrectly (17 to 22%). Clear inset markings were missing for some or all insets in 13 to 28% of papers (Figure 1c).
Many images contain information in color. We sought to determine whether color images were accessible to readers with deuteranopia, the most common form of color blindness, by using the color blindness simulator Color Oracle (https://colororacle.org/,RRID: SCR_018400). We evaluated only images in which the authors could have adjusted the image colors (i.e. fluorescence microscopy). Papers without any colorblind accessible figures were uncommon (3 to 6%), however 45% of cell biology papers and 21-24% of physiology and plant science papers contained some images that were inaccessible to readers with deuteranopia (Figure 2a). 17 to 34% of papers contained color annotations that were not visible to someone with deuteranopia.
Figure legends and, less often, titles typically provide essential information needed to interpret an image. This text provides information on the specimen and details of he image, while also explaining labels and annotations used to highlight structures or colors. 57% of physiology papers, 48% of cell biology papers and 20% of plant papers described the species and tissue or object shown completely. 5-17% of papers did not provide any such information (Figure 2b). Approximately half of the papers (47-58%) also failed or partially failed to adequately explain insets. Annotations of structures are better explained. Two-thirds of papers across all three fields clearly stated the meaning of all image labels, while 18 to 24% of papers provided partial explanations. Most papers (73 to 83%) completely explained the image colors by stating what substance each color represented or naming the dyes or staining technique used.
Finally, we examined the number of papers that used optimal image presentation practices for all criteria assessed in the study. Twenty-eight (16%) physiology papers, 19 (12%) cell biology papers and 6 (2%) plant sciences papers met all criteria for all image-based figures in the paper (data not shown in figure). In plant sciences and physiology, the most common problems were with scale bars, insets and specifying in the legend the species and tissue or object shown. In cell biology, the most common problems were with insets, colorblind accessibility, and specifying in the legend the species and tissue or object shown.
Designing image-based figures: How can we improve?
Our results obtained by examining 580 papers from three fields provide us with unique insights into the quality of reporting and the accessibility of image-based figures. Our quantitative description of standard practices in image publication highlights opportunities to improve transparency and accessibility to readers from different backgrounds. We have therefore outlined specific actions that scientists can take when creating images, designing multipanel figures, annotating figures and preparing figure legends.
Throughout the paper, we provide visual examples to illustrate each stage of figure preparation process. Other elements are often omitted to focus readers’ attention on the step illustrated in the figure. For example, a figure that highlights best practices for displaying scale bars may not include annotations designed to explain key features of the image. When preparing image-based figures in scientific publications, readers should address all relevant steps in each figure.
1. Choose a scale or magnification that fits your research question
Scientists should select an image scale or magnification that allows readers to clearly see features needed to answer the research question. Figure 3a shows Drosophila melanogaster at three different microscopic scales. The first focuses on the ovary tissue and might be used to illustrate the appearance of the tissue or show stages of development. The second focuses on a group of cells. In this example, the “egg chamber” cells show different nucleic acid distributions. The third example focuses on subcellular details in one cell, for example, to show finer detail of RNA granules or organelle shape.
When both low and high magnifications are necessary for one image, insets are used to show a small portion of the image at higher magnification (Figure 3b). The inset location must be accurately marked in the low magnification image. We observed that the inset position in the low magnification image was missing, unclear, or incorrectly placed in approximately one third of papers. Inset positions should be clearly marked by lines or regions-of-interest in a high-contrast color, usually black or white. Insets may also be explained in the figure legend. Care must be taken when preparing figures outside vector graphics suits, as insert positions may move during file saving or export.
2. Include a clearly labeled scale bar
Scale information allows audiences to quickly understand the size of features shown in images. This is especially important for microscopic images where we have no intuitive understanding of scale. Scale information for photographs should be considered when capturing images as rulers are often placed into the frame. Our analysis revealed that 10-29% of papers screened failed to provide any scale information and another third only provided incomplete scale information (Figure 1b). Scientists should consider the following points when displaying scale bars.
Every image type needs a scale bar: Authors usually add scale bars to microscopy images, but often leave them out in photos and clinical images, possibly because these depict familiar objects such a human or plant. Missing scale bars however adversely affect reproducibility. A size difference of 20% in between a published study and the reader’s lab animals, for example, could impact study results by leading to an important difference in phenotype. Scale bars may not be a standard feature of image acquisition and processing software for clinical images. Authors may need to contact device manufacturers to determine the image size and add height and width labels.
Scale bars and labels should be clearly visible: Short scale bars, thin scale bars and scale bars in colors that are similar to the image color can easily be overlooked (Figure 4). In multicolor images, it can be difficult to find a color that makes the scale bar stand out. Authors can solve this problem by placing the scale bar outside the image or onto a box with a more suitable background color.
Annotate scale bar dimensions on the image: Stating the dimensions along with the scale bar allows readers to interpret the image more quickly. Despite this, dimensions were typically stated in the legend instead (Figure 1b), possibly a legacy of printing processes that discouraged text in images. Dimensions should be in high resolution and large enough to be legible. In our set, we came across small and/or low-resolution annotations that were illegible in electronic versions of the paper, even after zooming in. Scale bars that are visible on larger figures produced by authors may be difficult to read when the size of the figure is reduced to fit onto a journal page. Authors should carefully check page proofs to ensure that scale bars and dimensions are clearly visible.
3. Use color wisely in images
Colors in images are used to display the natural appearance of an object, or to visualize features with dyes and stains. In the scientific context, adapting colors is possible and may enhance readers’ understanding, while poor color schemes may distract or mislead. Images showing the natural appearance of a subject, specimen or staining technique are generally presented in color (Figure 5). Examples are images showing plant sizes or histopathology images comparing fat tissue from mice on different diets. Images showing ielectron micrographs are captured in black and white (“greyscale”) by default and may be kept in greyscale to leverage the good contrast resulting from a full luminescence spectrum.
In many instances, scientists can choose whether to show greyscale or color images. Digital microscope setups capture each channel’s intensities in greyscale values. Assigning colors is optional, even though it is the default setting in imaging programs. When showing only one color channel, scientists may consider presenting this channel in greyscale to optimally display fine details. This may include variations in staining intensity or fine structures. When opting for color, authors should use greyscale visibility tests (Figure 6) to determine whether visibility is compromised. This can occur when dark colors, such as magenta, red, or blue, are shown on a black background.
4. Choose a colorblind accessible color palette
Fluorescent images with merged color channels visualize the co-localization of different markers. While many readers find these images to be visually appealing and informative, these images are often inaccessible to color blind co-authors, reviewers, editors, and readers. The most common form of colorblindness affects up to 8% of men and 0.5% of women of northern European ancestry.12 A study of articles published in top peripheral vascular disease journals revealed that 85% of papers with color maps and 58% of papers with heat maps used color palettes that were not colorblind safe.15 We show that approximately half of cell biology papers, and one third of physiology papers and plant science papers contained images that were inaccessible to readers with deuteranopia. Scientists should consider the following points to ensure that images are accessible to colorblind readers.
Select colorblind safe colors: Researchers should use colorblind safe color palettes for fluorescence and other images where color may be adjusted. Figure 7 illustrates how four different color combinations would look to viewers with different types of color blindness. Green and red are indistinguishable to readers with deuteranopia, whereas green and blue are indistinguishable to readers with tritanopia, a rare form of color blindness. Cyan and magenta are the best options, as these two colors look different to viewers with normal color vision, deuteranopia or tritanopia. Green and magenta are also shown, as scientists often prefer to show colors close to the excitation value of the fluorescent dyes, which are often green and red.
Display separate channels in addition to the merged image: Selecting a colorblind safe color palette becomes increasingly difficult as more colors are added. When the image includes three or more colors, authors are encouraged to show separate images for each channel, followed by the merged image (Figure 8). Individual channels may be shown in greyscale to make it easier for readers to perceive variations in staining intensity.
Use simulation tools to confirm that essential features are visible to colorblind viewers: Free tools, such as Color Oracle (RRID:SCR_018400), quickly simulate different forms of color blindness by adjusting the colors on the computer screen to simulate what a colorblind person would see.
5. Design the figure
Figures often contain more than one panel. Careful planning is needed to convey a clear message, while ensuring that all panels fit together and follow a logical order. A planning table (Figure 9a) helps scientists to determine what information is needed to answer the research question. The table outlines the objectives, types of visualizations required, and experimental groups that should appear in each panel. A planning table template is available on OSF.13 After completing the planning table, scientists should sketch out the position of panels, and the position of images, graphs, and titles within each panel (Figure 9b). Audiences read a page either from top to bottom and/or from right to left. Selecting one reading direction and arranging panels in rows or columns helps with figure planning. Using enough white space to separate rows or columns will visually guide the reader through the figure. The authors can then assemble the figure based on the draft sketch. A new tool called QuickFigures (RRID:SCR019082) may help scientists create multipanel figures using microscopy images.16
6. Annotate the figure
Annotations with text, symbols or lines allow readers from many different backgrounds to rapidly see essential features, interpret images, and gain insight. Unfortunately, scientists often design figures for themselves, rather than their audience.7 Examples of annotations are shown in Figure 10. Table 1 describes important factors to consider for each annotation type.
Choose the right amount of labeling. Figure 11 shows three levels of annotation. The barely annotated image (11a) is only accessible to scientists already familiar with the object and technique, whereas the heavily annotated version (11c) contains numerous annotations that obstruct the image and a legend that is time consuming to interpret. Panel 11b is more readable; annotations of a few key features are shown, and the explanations appear right below the image for easy interpretation. Explanations of labels are often placed in the figure legend. Alternating between examining the figure and legend is time consuming, especially when the legend and figure are on different pages. Figure 11d shows one option for situations where extensive annotations are required to explain a complex image. An annotated image is placed as a legend next to the original image. A semi-transparent white layer mutes the image to allow annotations to stand out.
Use abbreviations cautiously: Abbreviations are commonly used for image and figure annotation to save space, but inevitably require more effort from the reader. Abbreviations are often ambiguous, especially across fields. Authors should run a web search for the abbreviation.17 If the intended meaning is not a top result, authors should refrain from using the abbreviation or clearly define the abbreviation on the figure itself, even if it is already defined elsewhere in the manuscript. Note that in Figure 11, abbreviations have been written out below the image to reduce the number of legend entries.
Explain colors and stains: Explanations of colors and stains were missing in around 20% of papers. Figure 12 illustrates several problematic practices observed in our dataset, as well as solutions for clearly explaining what each color represents. This figure uses fluorescence images as an example; however we also observed many histology images in which authors did not mention which stain was used. Authors should describe how stains affect the tissue shown or use annotations to show staining patterns of specific structures. This allows readers who are unfamiliar with the stain to interpret the image.
Ensure that annotations are accessible to colorblind readers: Confirming that labels or annotations are visible to colorblind readers is important for both color and greyscale images (Figure 13). Up to one third of papers in our dataset contained annotations or labels that would not have been visible to someone with deuteranopia. This occurred because the annotations blended in with the background (i.e. red arrows on green plants) or the authors use the same symbol in colors that are indistinguishable to someone with deuteranopia to mark different features. Figure 13 illustrates how to annotate a greyscale image so that it is accessible to color blind readers. Using text to describe colors is also problematic for colorblind readers. This problem can be alleviated by using colored symbols in the legend or by using distinctly shaped annotations such as open vs. closed arrows, thin vs. wide lines, or dashed vs. solid lines. Color blindness simulators help in determining whether annotations are accessible to all readers.
7. Prepare figure legends
Each figure and legend are meant to be self-explanatory and should allow readers to quickly assess a paper or understand complex studies that combine different methodologies or model systems. To date, there are no guidelines for figure legends for images, as the scope and length of legends varies across journals and disciplines. Some journals require legends to include details on object, size, methodology or sample size, while other journals require a minimalist approach and mandate that information should not be repeated in subsequent figure legends.
Our data suggest that important information needed to interpret images was regularly missing from the figure or figure legend. This includes the species and tissue type, or object shown in the figure, clear explanations of all labels, annotations and colors, and markings or legend entries denoting insets. Presenting this information on the figure itself is more efficient for the reader, however any details that are not marked in the figure should be explained in the legend.
Discussion
A flood of images is published every day in scientific journals and the number is continuously increasing. Of these, around 4% likely contain intentionally or accidentally manipulated images.3 Our data show that, in addition, most papers show images that are not fully interpretable due to issues with scale markings, annotation, and/or color. This is a problem for readers interested in the data, and uninterpretable figures may contribute to the “reproducibility crisis”. Images are also increasingly submitted to image archives to make image data widely accessible and permit future re-analyses. A substantial fraction of images that are neither human nor machine-readable lowers the potential impact of such archives. Based on our data examining common problems with published images, we provide a few simple recommendations, with examples illustrating good practices. We hope that these recommendations will help authors to make their published images legible and interpretable.
Limitations
While most results were consistent across the three subfields of biology, findings may not be generalizable to other fields. Our sample included the top 15 journals that publish original research for each field. Almost all journals were indexed in PubMed. Results may not be generalizable to journals that are un-indexed, have low impact factors, or are not published in English. Data abstraction was performed manually due to the complexity of the assessments. Error rates were 5% for plant sciences, 4% for physiology and 3% for cell biology.
Actions journals can take to make image-based figures more transparent and easier to interpret
The role of journals in improving the quality of reporting and accessibility of image-based figures should not be overlooked. There are several actions that journals might consider.
Screen manuscripts for figures that are not colorblind safe: Open source automated screening tools18 may help journals to efficiently identify common color maps that are not colorblind safe.
Re-evaluate limits on the number of figures: Limitations on the number of figures originally stemmed from printing costs calculations, which are becoming increasingly irrelevant as scientific publishing moves online. Unintended consequences of these policies include the advent of large, multipanel figures. These figures are often especially difficult to interpret because the legend appears on a different page, or the figure combines images addressing different research questions.
Reduce or eliminate page charges for color figures: As journals move online, policies designed to offset the increased cost of color printing are no longer needed. The added costs may incentivize authors to use greyscale in cases where color would be beneficial.
Encourage authors to explain labels or annotations in the figure, rather than in the legend: This is more efficient for readers.
Encourage authors to share image data in public repositories: Open data benefits authors and the scientific community.19-21
How can the scientific community improve image-based figures?
The role of scientists in the community is multi-faceted. As authors, scientists should familiarize themselves with guidelines and recommendations, such as ours provided above. As reviewers, scientists should ask authors to improve erroneous or uninformative image-based figures. As instructors, scientists should ensure that bioimaging and image data handling is taught during undergraduate or graduate courses, and support existing initiatives such as NEUBIAS22 (Network of European Bioimage Analysts) that aim to increase training opportunities in bioimaging. Scientists are also innovators. As such they should support emerging image data archives. Repositories for other types of data are already widespread, however the idea of image repositories has only recently gained traction.23 Existing image databases include the Allen Brain Atlas, the Image Data Resource24 and the emerging BioImage Archives.23 Springer Nature encourages authors to submit imaging data to the ImageDataResource, IDR.24 While scientists have called for common quality standards,23 such standards have not been defined, implemented, or taught. Examining standard practices for reporting images in scientific publications, as outlined here, is one strategy for establishing common quality standards.
In the future, it is possible that each image published electronically in a journal or submitted to an image data repository will follow good practice guidelines, and will be accompanied by expanded “meta-data” or “alt-text/attribute” files. Alt-text is already published in html to provide context if an image cannot be accessed (e.g. by blind readers). Similarly, images in online articles and deposited in archives could contain essential information in a standardized format. The information could include the main objective of the figure, specimen information, ideally with research resource identifier25 (RRID), specimen manipulation (dissection, staining, RRID for dyes and antibodies used), as well as the imaging method including essential items from meta-files of the microscope software, information about image processing and adjustments, information about scale, annotations, insets, and colors shown, and confirmation that the images are truly representative.
Conclusions
Our meta-research study of standard practices for presenting images in three fields highlights current shortcomings in publications. Each day 2500 new publications appear on PubMed of which 500 are estimated to contain images. Our survey data suggest that most of these papers will have deficiencies in image presentation, which may affect legibility, interpretability, rigor, and reproducibility. These observations lead to targeted recommendations for improving the quality of published images. Our recommendations are available as a slide set via the Open Science Framework and can be used in teaching best practice and avoid misleading or uninformative image-based figures. Our analysis underscores the need for standardized image publishing guidelines. Adherence to such guidelines will allow the scientific community to unlock the full potential of image collections in the life sciences for current and future generations of researchers.
Methods
Systematic review
We examined original research articles that were published in April of 2018 in the top 15 journals that publish original research for each of three different categories (physiology, plant science, cell biology). Journals for each category were ranked according to 2016 impact factors listed for the specified categories in Journal Citation Reports. Journals that only publish review articles or that did not publish an April issue were excluded. We followed all relevant aspects of the PRISMA guidelines.26 Items that only apply to meta-analyses or are not relevant to literature surveys were not followed. Ethical approval was not required.
Search strategy
Articles were identified through a PubMed search, as all journals were PubMed indexed. Electronic search results were verified by comparison with the list of articles published in April issues on the journal website. The electronic search used the following terms:
Physiology: (“Journal of pineal research”[Journal] AND 3[Issue] AND 64[Volume]) OR (“Acta physiologica (Oxford, England)”[Journal] AND 222[Volume] AND 4[Issue]) OR (“The Journal of physiology”[Journal] AND 596[Volume] AND (7[Issue] OR 8[Issue])) OR ((“American journal of physiology. Lung cellular and molecular physiology”[Journal] OR “American journal of physiology. Endocrinology and metabolism”[Journal] OR “American journal of physiology. Renal physiology”[Journal] OR “American journal of physiology. Cell physiology”[Journal] OR “American journal of physiology. Gastrointestinal and liver physiology”[Journal]) AND 314[Volume] AND 4[Issue]) OR (“American journal of physiology. Heart and circulatory physiology”[Journal] AND 314[Volume] AND 4[Issue]) OR (“The Journal of general physiology”[Journal] AND 150[Volume] AND 4[Issue]) OR (“Journal of cellular physiology”[Journal] AND 233[Volume] AND 4[Issue]) OR (“Journal of biological rhythms”[Journal] AND 33[Volume] AND 2[Issue]) OR (“Journal of applied physiology (Bethesda, Md. : 1985)”[Journal] AND 124[Volume] AND 4[Issue]) OR (“Frontiers in physiology”[Journal] AND (“2018/04/01”[Date - Publication] : “2018/04/30”[Date - Publication])) OR (“The international journal of behavioral nutrition and physical activity”[Journal] AND (“2018/04/01”[Date - Publication] : “2018/04/30”[Date - Publication]))
Plant science: (“Nature plants”[Journal] AND 4[Issue] AND 4[Volume]) OR (“Molecular plant”[Journal] AND 4[Issue] AND 11[Volume]) OR (“The Plant cell”[Journal] AND 4[Issue] AND 30[Volume]) OR (“Plant biotechnology journal”[Journal] AND 4[Issue] AND 16[Volume]) OR (“The New phytologist”[Journal] AND (1[Issue] OR 2[Issue]) AND 218[Volume]) OR (“Plant physiology”[Journal] AND 4[Issue] AND 176[Volume]) OR (“Plant, cell & environment”[Journal] AND 4[Issue] AND 41[Volume]) OR (“The Plant journal : for cell and molecular biology”[Journal] AND (1[Issue] OR 2[Issue]) AND 94[Volume]) OR (“Journal of experimental botany”[Journal] AND (8[Issue] OR 9[Issue] OR 10[Issue]) AND 69[Volume]) OR (“Plant & cell physiology”[Journal] AND 4[Issue] AND 59[Volume]) OR (“Molecular plant pathology”[Journal] AND 4[Issue] AND 19[Volume]) OR (“Environmental and experimental botany”[Journal] AND 148[Volume]) OR (“Molecular plant-microbe interactions : MPMI”[Journal] AND 4[Issue] AND 31[Volume]) OR (“Frontiers in plant science”[Journal] AND (“2018/04/01”[Date - Publication] : “2018/04/30”[Date - Publication])) OR (“The Journal of ecology” (“2018/04/01”[Date - Publication] : “2018/04/30”[Date - Publication]))
Cell biology: (“Cell”[Journal] AND (2[Issue] OR 3[Issue]) AND 173[Volume]) OR (“Nature medicine”[Journal] AND 24[Volume] AND 4[Issue]) OR (“Cancer cell”[Journal] AND 33[Volume] AND 4[Issue]) OR (“Cell stem cell”[Journal] AND 22[Volume] AND 4[Issue]) OR (“Nature cell biology”[Journal] AND 20[Volume] AND 4[Issue]) OR (“Cell metabolism”[Journal] AND 27[Volume] AND 4[Issue]) OR (“Science translational medicine”[Journal] AND 10[Volume] AND (435[Issue] OR 436[Issue] OR 437[Issue] OR 438[Issue])) OR (“Cell research”[Journal] AND 28[Volume] AND 4[Issue]) OR (“Molecular cell”[Journal] AND 70[Volume] AND (1[Issue] OR 2[Issue])) OR(“Nature structural & molecular biology”[Journal] AND 25[Volume] AND 4[Issue]) OR (“The EMBO journal”[Journal] AND 37[Volume] AND (7[Issue] OR 8[Issue])) OR (“Genes & development”[Journal] AND 32[Volume] AND 7-8[Issue]) OR (“Developmental cell”[Journal] AND 45[Volume] AND (1[Issue] OR 2[Issue])) OR (“Current biology : CB”[Journal] AND 28[Volume] AND (7[Issue] OR 8[Issue])) OR (“Plant cell”[Journal] AND 30[Volume] AND 4[Issue])
Screening
Screening for each article was performed by two independent reviewers (Physiology: TLW, SS, EMW, VI, KW, MO; Plant science: TLW, SJB; Cell biology: EW, SS) using Rayyan software (RRID:SCR_017584), and disagreements were resolved by consensus. Both reviewers screened all articles published in each journal between April 1 and April 30, 2018 to identify full length, original research articles (Table S1, Table S2, Table S3, Figure S1) published in the print issue of the journal. Articles for online journals that do not publish print issues were included if the publication date was between April 1 and April 30, 2018. Articles were excluded if they were not original research articles, or if an accepted version of the paper was posted as an “in press” or “early release” publication; however, the final version did not appear in the print version of the April issue. Articles were included if they contained at least one eligible image, such as a photograph, an image created using a microscope or electron microscope, or an image created using a clinical imaging technology such as ultrasound or MRI. Blot images were excluded, as many of the criteria in our abstraction protocol cannot easily be applied to blots. Computer generated images, graphs and data figures were also excluded. Papers that did not contain any eligible images were excluded.
Abstraction
All abstractors completed a training set of 25 articles before abstracting data. Data abstraction for each article was performed by two independent reviewers (Physiology: AA, AV; Plant science: MO, TLA, SA, KW, MAG, IF; Cell biology: IF, AA, AV, KW, MAG). When disagreements could not be resolved by consensus between the two reviewers, ratings were assigned after a group review of the manuscript. Eligible manuscripts were reviewed in detail to evaluate the following questions according to a predefined protocol (available at: https://osf.io/b5296/?view_only=9166dc4099504a9f8635add45ed70b0d). Supplemental files were not examined, as supplemental images may not be held to the same peer review standards as those in the manuscript.
The following items were abstracted:
Types of images included in the paper (photograph, microscopy image, electron microscopy image, image created using a clinical imaging technique such as ultrasound or MRI, other types of images)
Did the paper contain appropriately labeled scale bars for all images?
Were all insets clearly and accurately marked?
Were all insets clearly explained in the legend?
Is the species and tissue, object, or cell line name clearly specified in the figure or legend for all images in the paper?
Are any annotations, arrows or labels clearly explained for all images in the paper?
Among images where authors can control the colors shown (i.e. fluorescence microscopy), are key features of the images visible to someone with the most common form of colorblindness (deuteranopia)?
If the paper contains colored labels, are these labels visible to someone with the most common form of color blindness (deuteranopia)?
Are colors in images explained either on the image or within the legend?
Questions 7 and 8 were assessed by using Color Oracle27 (RRID:SCR_018400) to simulate the effects of deuteranopia.
Verification
Ten percent of articles in each field were randomly selected for verification abstraction, to ensure that abstractors in different fields were following similar procedures. Data were abstracted by a single abstractor (TLW). Results were compared with consensus results from the two independent abstractors for each paper.
Statistical Analysis
Data are presented as n (%). Summary statistics were calculated using Python (RRID:SCR_008394, version 3.6.9, libraries NumPy 1.18.5 and Matplotlib 3.2.2).
Funding
TLW was funded by American Heart Association grant 16GRNT30950002 and a Robert W. Fulk Career Development Award (Mayo Clinic Division of Nephrology & Hypertension). LHH was supported by The Hormel Foundation and National Institutes of Health grant CA187035.
Supplemental Tables
Acknowledgements
We thank Tatyana Grinenko, Andreas Müller and John A. Nyakatura for generously sharing example images, and Falk Hillmann and Thiery Soldati for providing the amoeba strains used for imaging. Some of the early career researchers who participated in this research would like to thank their principal investigators and mentors for supporting their efforts to improve science.
Footnotes
↵* Co-first authors
https://osf.io/b5296/?view_only=9166dc4099504a9f8635add45ed70b0d