Biology of the Cell
© Société Française des Microscopies and Société Biologie Cellulaire de France
Edited By: René-Marc Mège, Paris, France
Impact Factor: 2.552
ISI Journal Citation Reports © Ranking: 2015: 120/187 (Cell Biology)
Online ISSN: 1768-322X
Effective with the 2013 volume, this journal is being published in an online-only format. No printed edition is available. Your article will therefore appear online-only. Furthormore, there will no cost to authors for the publication of colour images in the online-only edition. Please see the author instructions for full details.
Biology of the Cell is a journal published since 1984 by the French Societies of Cell Biology and of Microscopies. The journal publishes original research articles and reviews on all aspects of cellular, molecular and structural biology, developmental biology, cell physiology and evolution. It will publish articles or reviews contributing to the understanding of the elementary biochemical and biophysical principles of live matter organization from the molecular, cellular and tissues scales and organisms.
To justify publication in BoC, manuscripts must make a significant contribution to our understanding of the mechanistic relationships that govern cellular functions. Descriptive work will only be published if it establishes a new experimental model or if the data provide a structural basis for the interpretation of functional data.
(a) Animal and human studies
All animal studies and experimental work using human tissues should be performed in accordance with the legal requirements of the relevant local or national authority and a statement to this effect must be included in the Materials and Methods section.
Authors may wish to refer to the 'ARRIVE' Guidelines on the reporting of animal research.
The Editorial Board will not accept papers where ethical aspects of any nature are, in the Board's opinion, open to doubt.
(b) Scientific publication
BoC is a member of COPE (Committee on Publication Ethics) and endorsed its guidelines, which are available at http://www/publicationethics.org.uk. Complaints against the Journal must be submitted in writing to the Editor-in-Chief; if a complaint is not resolved to the satisfaction of the complainant they have the option of referring the matter to COPE.
Notwithstanding, the Editorial Board will not accept papers where the ethical aspects are, in the Board's opinion, open to doubt.
BoC will always investigate fully any matters of apparent misconduct that it becomes aware of.
BoC follows the guidelines published by COPE in respect of the retraction of articles.
1.3 Originality of papers
When submitting a manuscript to BoC it is understood that the data have been neither published nor also submitted for publication elsewhere in any language (excluding abstracts for conferences of less than one page and without illustrations). Any manuscript, submitted or in press, that is related to the manuscript submitted to BoC should be included with the submitted material. Such material will be made available with the manuscript to the reviewers.
1.4 Financial interests
All authors are asked to disclose any financial interests and sources of research funding that could be considered to affect the integrity of the scientific work presented. If appropriate, a general statement should be included in the Acknowledgements section of the manuscript. All funding sources, institutional and corporate, should be credited in the Funding section, with the funding agency written out in full followed by the grant number in square brackets.
BoC endorses the Vancouver Guidelines on authorship as defined in the International Committee of Medical Journal Editors' (ICMJE) Uniform Requirements for Manuscripts Submitted to Biomedical Journals, namely that entitlement to authorship should be based on all of the following criteria: (1) substantial contributions to conception and design, or acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it for important intellectual content;(3) final approval of the version to be published. Acquisition of funding, collection of data, or general supervision of the research group, alone, does not justify authorship. All contributors who do not meet the criteria for authorship should be listed in the Acknowledgements.
A paragraph outlining the contribution of each author to the study should be provided on submission. This will be published as part of the paper.
The Journal also participates in the new CrossRef service CrossCheck (http://www.crossref.org/crosscheck.html), a plagiarism screening tool that allows the comparison of authored work against the content in the internet database of published work to highlight matching or similar text sections. Please be aware that manuscripts submitted to Biology of the Cell will be subject to random testing using the CrossCheck software. Please note that papers with a high percentage of copied text will be rejected.
1.7 No page charges. No colour charges.
There are no page or colour charges for publication in BoC.
1.8 Cover images
Authors of accepted manuscripts are encouraged to submit outstanding photographs or graphical drawings that may be used as the cover image for the issue of BoC in which their manuscripts will be published. The cover authors will receive a complimentary high-resolution cover in PDF file. All the covers will be displayed in Cover Gallery on Wiley Online Library.
1.9 Data acquired using small interfering RNAs (siRNAs)
In the context of these recommendations, the term small interfering RNAs includes all small RNA (or modified nucleic acid) molecules that form a duplex with a target RNA and thereby modify the processing, stability of the translation of the target RNA.
Small interfering RNAs are becoming a much-used tool in cell biology to modify gene expression. However, the use of these molecules are not prone to artifacts.To help ensure that the effects of interfering RNAs reported in manuscripts are specific changes in the expected gene products, and not the consequences of the small interfering RNA affecting 'off-target' RNAs, the following experimental verifications are recommended in addition to the usual computer-based analyses:
More than one interfering RNA should be used for the same target RNA
Depending on the interfering RNA used, the change, or lack of change, in the amount of targeted RNA or protein should be quantified by an appropriate method
- When appropriate, experiments to repress the cellular changes caused by the interfering RNA should be done; for example, by restoring the level of the target RNA protein product by using a modified mRNA that is no longer recognized by the intefering RNA.
Further controls may be requested by the reviewers, depending on the advances in the field.
1.10 Biology of the Cell Prizes
At the discretion of the Editorial Board, Biology of the Cell will award the following prizes annually: 'Best Research Article' and 'Best Cover Image'.
2. Manuscript types and organization
Research Articles: These should be fully documented reports of original research. The length of a manuscript must be justified by the data presented. Research articles may contain up to 8 display elements (figures and/or tables), manuscripts should be divided into sections as described under 2.2. Manuscript organization and length below.
Short Communication: This manuscript type should contain results that are brief, novel, timely and/or of such importance that rapid publication is warranted. They should be subdivided into titled sections similar to Research Articles as described under 2.2. Manuscript organization and length below. Short communications should not exceed 2500 words (including references as well as figures, tables and their legends) and may contain up to four display elements (figures and/or tables).
Reviews: Both solicited and unsolicited reviews will be considered for publication in BoC. Authors wishing to submit a review are invited to contact the Associate Editors for Reviews directly or though the Editor-in-Chief's office (see section 5, Addresses for correspondence).
Scientiae Forum: Manuscripts submitted to this section must enter into one of the following categories. 'Models and Speculations' on all aspects of cell structure and function. 'Primer Reviews' that introduce specific aspects of cell biology to scientists working in unrelated fields of interest. 'History of Biology and the Cell' that places current research activities within their historical context.
Authors requesting information on whether a manuscript is appropriate for the Scientiae Forum should contact one of the Associate Editors in charge of the particular subsection (see section 5, Addresses for correspondence).
Meeting Reports: Informative reports of meetings are also published if the subject is considered to be of interest to BoC readers. Enquiries should be sent to the Editor-in-Chief (see section 5, Addresses for correspondence).
In order to aid the reader to quickly extract a maximum of information from publications in BoC, there are specific facets to the organization of Research articles, Short Communications, Reviews and Scientiae Forum contributions. Please make sure that you consult the specific instructions for the type of manuscript you are submitting.
Authors should be aware that all material which is integral for the understanding of the paper has to be placed in the main document. Only extensive datasets (e.g. proteomics screens, sequence data and videos) can be published as supplementary online data (see section 2.8, Supplementary material). In addition, panels in composite figures should be judiciously arranged to make the most efficient use of page space.
Title Page: Give the title of the manuscript, the names, affiliations and addresses of all the authors, indicate the corresponding author (only one) and give their telephone number, fax number and email address. Provide a running title of less than 50 characters including spaces. List up to five key words.
Abbreviations: Only use abbreviations for terms that are used at least three times and define them when first used in the text. A list of abbreviations used should also be supplied at the end of the text. Abbreviations given in the BoC standard abbreviations list can be used without definition (see section 6).
Acknowledgements: A general statement should be included here if financial interests or research funding could be perceived to compromise the integrity of the published work.
Funding: All funding sources (institutional and corporate) should be credited, with the funding agency written out in full followed by the grant number in square brackets.
Graphical Abstract: For all manuscripts a short text for the table of contents of the issue (ca. 450–490 characters) should be included as the last page of the manuscript. The text should (ideally with the help of a graphic) sum up the article in a poignant and interesting manner. Repetition or a paraphrase of the title and presentation of experimental details should be avoided. Please include the Figure you wish to display.
Abstract: The abstract should be divided into four sections: Background Information, Results, Conclusions and Significance. The total length should not exceed 350 words. The Significance section should contain a short (2-3 sentences), stand-alone statement that highlights the impact of the article on its field of study (e.g. translational potential, novelty, etc). Please note that repetion of the same information among the abstract sections should be avoided. Abbreviations should not be used and references, if absolutely required, should be given in full.
Introduction: Summarize prior knowledge on the research presented. Do not make an extensive review. Present any theoretical background required to understand the experiments. The results can be briefly stated.
Results and Discussion: These two sections can be combined if desired. All conclusions must be rigorously supported by the data. Speculative interpretations of the results should be restricted to the Discussion section.
Materials and Methods: Sufficient detail should be given to allow others to repeat the experiments. Only modifications to already published methods should be described.
Author contribution: A paragraph outlining the contribution of each author to the study should be provided. This will be published as part of the paper.
Examples of authors' roles include: concept and design of the research; carrying out the experimental work; providing reagents; data analysis and interpretation; writing of the article.
Abstract: The abstract should be written as a single paragraph and give a self-explanatory synopsis of the publication that is directly suitable for abstracting services. It should not exceed 200 words. Abbreviations should not be used and references, if absolutely required, should be given in full.
Text: This should be divided into separate sections, with informative headings, as considered appropriate by the author. The first section should introduce the review. The authors are asked to give definitions, throughout the text, of words or terms with which all readers may not be acquainted. These will be printed on the appropriate pages within a distinctive box. The referees and/or the editorial board may suggest additional definitions. In addition, for reviews, references that are particularly important (landmark/milestone), or for Primer Reviews those that are recommended as further reading, should be indicated by an asterisk (*).
Abstract: The abstract should be written as a single paragraph and give a self-explanatory synopsis of the publication that is directly suitable for abstracting services. It should not exceed 100 words. Abbreviations should not be used and references, if absolutely required, should be given in full.
Text: This should be divided into separate sections, with informative headings, as considered appropriate by the author. The first section should introduce the subject treated.
Animated versions of suitable figures can be produced by the Editorial Office for Reviews and Primer Reviews. Authors are requested to indicate on submission whether any figures would benefit from this treatment.
In all manuscripts, references should be cited within the text as follows:
One or two authors: (Jaffe, 2003); (Schenk and Matteoli, 2004)
More than two authors: (McNew et al., 2000)
If style requires, the format McNew et al. (2000) is also acceptable.
Multiple dates, same author: (Smith et al., 2001a, 2001b)
In date order: (Zhou et al., 1992; Ari et al., 2000)
In the list, references should appear in alphabetical order by first author's last name. Include all authors' names (do not use "et al."), year, complete article title, journal, volume and inclusive page numbers. Abbreviate journal names according to PubMed; spell out the names of unlisted journals. Do not list unpublished material but cite parenthetically within the text as "unpublished data". Do not use others forms such as "manuscript in preparation," "manuscript submitted," "unpublished results" or "unpublished observation". Unpublished data may not be cited in the Materials and Methods section. Unpublished data provided by a person(s) who is not an author of the article must be cited as a "personal communication". An authorization from this person(s) must be provided with the manuscript. Abstracts to meetings should not appear in the reference list but incorporated parenthetically into the text, giving the authors' names, meeting name and year, and abstract number. Adhere to the reference formats provided by the following examples:
Published article: Crane, R., Gadea, B., Littlepage, L., Wu, H. and Ruderman J.V. (2004) Aurora A, meiosis and mitosis. Biol. Cell 96, 215-229
Published article with DOI only: Lopez-Soler, R.I., Moir, R.D., Spann, T.P., Stick, R. and Goldman, R.D. (2008) A role for nuclear lamins in nuclear envelope assembly. J. Cell Biol. 10.1083/jcb.200801025
Article in press: Murakami, M.S., Moody, S.A., Daar, I.O. and Morrison, D.K. (2008) Morphogenesis duringXenopus gastrulation requires Wee1-mediated inhibition of cell proliferation. Development, in the press
Complete Book: Scheel, D. and Wasternack, C.(2002) Plant Signal Transduction, Oxford University Press, Oxford
Chapter in Book: DeMey, J. (1986) The preparation and use of gold probes. In Immunocytochemistry: Practical Applications in Pathology and Biology (Polak, J.M. and Van Noorden, S. eds.), pp. 115-145, Wright, Bristol
For reviews, publications that are particularly important (landmark/milestone) or for Primer Reviews those that are recommended as further reading should be indicated by an asterisk (*).
Legends: Legends should be self-explanatory, starting with an informative title, and contain all the necessary information without reference to the text except for general experimental details. Group all legends (tables and illustrations) together at the end of the text on a new page.
Tables: Tables, numbered consecutively with Arabic numerals (1, 2, 3 etc), should have a heading and a legend.
Figures: Each figure should be numbered consecutively with Arabic numerals and must have an informative title and a legend. Do not number the separate panels of composite figure as separate figures. All figures in electronic form must be prepared and saved in TIFF or EPS format at publication quality resolution (see Manuscripts accepted for publication) before conversion to the PDF format required for the initial submission. Colour illustrations should be saved in RGB format. Black and white illustrations should be saved as half-tones (grey scale). All micrographs must include a scale bar. For lettering on line drawings only Times, Helvetica, Arial or Symbol fonts should be used; the use of different fonts may lead to loss of improperly converted characters. Authors are encouraged to check that when figures are reduced to publication size (maximum width: one column, 80mm; two columns, 170mm; maximum height 205mm) all the required details are visible. For composite figures, please ensure that the individual panels are arranged so as to give the most efficient use of the available space for the figure while ensuring that all the required details are visible.
Image acquisition and manipulation: Images will be checked for manipulation when a paper is accepted. The Editorial Board may request that authors supply the original data for comparison against the prepared figures. If authors are unable to comply with such a request, the acceptance of the paper may be withdrawn.
Biology of the Cell endorses the guidelines given in the Instructions for Authors of the Journal of Cell Biology, from where the following is adapted by kind permission of Rockefeller University Press:
The following information must be provided about the acquisition and processing of images:
1. Make and model of microscope
2. Type, magnification, and numerical aperture of the objective lenses
4. Imaging medium
6. Camera make and model
7. Acquisition software
8. Any subsequent software used for image processing, with details about types of operations involved (e.g. type of deconvolution, 3D reconstructions, surface or volume rendering, gamma adjustments, etc.).
No specific feature within an image may be enhanced, obscured, moved, removed or introduced. The grouping of images from different parts of the same gel, or from different gels, fields or exposures must be made explicit by the arrangement of the figure (i.e. using dividing lines) and in the text of the figure legend. Adjustments of brightness, contrast or colour balance are acceptable if they are applied to the whole image and as long as they do not obscure, eliminate or misrepresent any information present in the original, including backgrounds.The background of figures should be clearly distinct from the surrounding page. Non-linear adjustments (e.g. changes to gamma settings) must be disclosed in the figure legend.
Authors are encouraged to read the papers by M. Rossner and K. M. Yamada (2004) J. Cell Biol. 166, 11-15and A. J. North (2006) J.Cell Biol. 172, 9-18
Supplementary material (extensive tables from large data sets and videos): All other material which is part of the study should be part of the main manuscript. Exception: voluminous sequence data (e.g. proteomics screens) and alignment diagrams are better presented as supplementary data. This is considered by BoC as published data and therefore should not be considered as a depositary for "unpublished data". BoC will also post video files with the online version of the publication. These should be cited at the relevant place(s) in the Results section and also in the legend to any illustration that contains images taken from these videos. An "Online Supplementary Material" section that provides a brief description of additional data, and videos should be included at the end of the Results section. All illustrations and videos presented as supplementary data must be accompanied by title and a self-explanatory legend.
2.9 Online Protocols
Authors will be invited, at the discretion of the Editorial Board, to provide detailed protocols of specific techniques/methods utilized in their Research Article that are deemed of particular interest or novelty. These Online Protocols will be published online, accompanying the Version of Record (VoR) of the Research Article.
3. Online submission
Papers should be submitted online http://mc.manuscriptcentral.com/boc where full instructions are available.
Submission of a paper to BoC implies that it has been approved by all the named authors, that all persons entitled to authorship have been so named, that it reports unpublished work that is not under consideration for publication elsewhere in any language, that conflicts of interest are declared and that if the paper is accepted for publication the authors will grant to Société Francaise des Microscopies, Société de Biologie Cellulaire de France and Wiley-Blackwell the right to publish the paper (see section 4.4, Copyright policy).
• Covering letter including the names of two members of the Editorial Board to act as referees (see the list on the Journal web page: http://www.biolcell.net/), and the names, addresses and email addresses of four possible referees (two of whom should be from a country other than your home country).
• Master electronic copy of typescript, single-spaced, as separate files of text and illustrations (the text file MUST be provided as a separate file in MS Word format, the figures can be provided as a single pdf at this stage, or also as individual image files):
- complete text in appropriate style, pages numbered
- full names and addresses of authors
- full name, address, telephone and fax numbers and email address of corresponding author (all correspondence and proofs will be sent to this author)
• Related papers in press or under editorial consideration
• Evidence of approval of personal communications
• Evidence of submission of nucleic acid or protein sequences to an appropriate data bank.
On acceptance, authors will be requested to supply the text and figures of the final version.
Text revisions must not be marked in the electronic copy. Authors must ensure that the file has been updated to incorporate all revisions, and hence that the file matches the final version of the manuscript seen by the reviewers. Our preferred word-processing format is Word for Windows version 6.
Tables should be prepared using the Microsoft Word table editor.
No artwork should be incorporated into the text files. Artwork should be in either TIFF or EPS format according to the specifications below and each figure saved as a separate file:
(a) black and white figures (e.g. line diagrams, bar graphs etc) as tiff files at 600 dots per inch (dpi) or .eps files at 1200 dpi only.
(b) figures containing grey scale (including gel images) as .tiff files only. These files should be at least 300 dpi.
(c) figures containing colour as .tiff (or .eps) files only. We can only accept files that are prepared in RGB (CMYK should not be used). These files should be at least 300 dpi.
Full instructions will be provided on acceptance.
If your paper is accepted, the author identified as the formal corresponding author for the paper will receive an email prompting them to login into Author Services; where via the Wiley Author Licensing Service (WALS) they will be able to complete the license agreement on behalf of all authors on the paper.
(a) For authors signing the copyright transfer agreement
If the OnlineOpen option is not selected the corresponding author will be presented with the copyright transfer agreement (CTA) to sign. The terms and conditions of the CTA can be previewed in the samples associated with the Copyright FAQs below:
CTA Terms and Conditions http://exchanges.wiley.com/authors/faqs---copyright-_301.html
(b) For authors choosing OnlineOpen
If the OnlineOpen option is selected the corresponding author will have a choice of the following Creative Commons License Open Access Agreements (OAA):
Creative Commons Attribution License OAA
Creative Commons Attribution Non-Commercial License OAA
Creative Commons Attribution Non-Commercial -NoDerivs License OAA
To preview the terms and conditions of these open access agreements please visit the Copyright FAQs hosted on Wiley Author Services
http://exchanges.wiley.com/authors/faqs---copyright-_301.html and visit
If you select the OnlineOpen option and your research is funded by certain funders [e.g. The Wellcome Trust and members of the Research Councils UK (RCUK) or the Austrian Science Fund (FWF)], you will be given the opportunity to publish your article under a CC-BY license supporting you in complying with your Funder requirements. For more information on this policy and the Journal’s compliant self-archiving policy please visit: http://www.wiley.com/go/funderstatement.
4.5 Accepted Articles
Biology of the Cell is covered by the Accepted Articles service whereby peer reviewed, accepted articles are published online as within 5 days of acceptance, without having been copy-edited typeset. Accepted Articles appear in PDF-only format, without the accompanying full-text HTML. Each manuscript is assigned a Digital Object Identifier (DOI), which allows the article to be cited and tracked before it is allocated to an issue. After print publication, the DOI remains valid and can continue to be used to cite and access the article.
4.6 Early View
Biology of the Cell is covered by John Wiley & Sons' Early View service Early View articles are complete full-text articles published online in advance of their publication in a printed issue. Early View articles are complete and final. They have been fully reviewed, revised and edited for publication, and the authors' final corrections have been incorporated. Because they are in final form, no changes can be made after online publication. The nature of Early View articles means that they do not yet have volume, issue or page numbers, so Early View articles should be cited using its DOI.
4.7 Online Open
OnlineOpen is available to authors of primary research articles who wish to make their article available to non-subscribers on publication, or whose funding agency requires grantees to archive the final version of their article. With OnlineOpen the author, or a funding agency or institution, pays a fee to ensure that the article is made available to non-subscribers. For the full list of terms and conditions, see http://wileyonlinelibrary.com/onlineopen#OnlineOpen_Terms. Any authors wishing to send their paper Online Open will be required to complete the payment form available from our website at: https://wileyonlinelibrary.com/onlineopen . Prior to acceptance there is no requirement to inform an Editorial Office that you intend to publish your paper Online Open if you do not wish to. All Online Open articles are treated in the same way as any other article. They go through the journal's standard peer-review process and will be accepted or rejected based on their own merit.
Proofs will be sent to the corresponding author as a PDF together with instructions. Proofs must be returned within 48 hours. Excessive text alterations at proof stage are subject to approval by the Editor-in-Chief and a charge may be made. Figure reprocessing at the author's request will also be subject to charge.
4.9 Public Access Compliance
Biology of the Cell is in full compliance with all public access requirements (NIH, HHMI, Wellcome Trust, Research Councils UK (eg. MRC, BBSRC)), Biology of the Cell submits accepted manuscripts that have been funded by the agencies above to PubMedCentral and PubMedCentralUK. The authors will receive confirmation and further instructions directly from PubMedCentral. From April 2008, the NIH mandated grantees to deposit their peer-reviewed author manuscripts in PubMed Central, to be made publicly available within 12 months of publication. The NIH mandate applies to all articles based on research that has been wholly or partially funded by the NIH and that are accepted for publication on or after April 7, 2008. In order to help authors comply with the NIH mandate, for papers accepted for publication in Biology of the Cell after this date Wiley-Blackwell will post the accepted manuscript (incorporating all amendments made during peer review, but prior to the publisher's copy-editing and typesetting) of articles by NIH grant-holders to PubMed Central at the point of acceptance by the journal. This version will then be made publicly available in PubMed Central 12 months after publication. Following the deposit Wiley-Blackwell authors will receive further communications from the NIH with respect to the submission. For further information, click here.
5.1 Editor-in-Chief's office
René Marc MEGE
"Cell Adhesion and Mechanics" lab
4ème étage porte 404B
Institut Jacques Monod
Université Paris Diderot/CNRS
Bâtiment Buffon - 15 rue Hélène Brion
Paris, F-75205, Cedex 13
5.2 Editorial correspondence
Correspondence about papers:
Tel: +49 6201 606380
Fax: +49 6201 606172
All correspondence about offprints should be addressed to: email@example.com. Authors can visit http://offprint.cosprinters.com/blackwell for more information.
Authors can download an electronic PDF offprint of their article upon publication through Wiley-Blackwell’s Author Services.
All correspondence about subscriptions to the journal, claims and back issues should be addressed to:
Wiley-Blackwell Customer Services at firstname.lastname@example.org
List of standard abbreviations that may be used without definition in the title, running title and text:
ADP (CDP, GDP, IDP, UDP, XDP, TDP)
adenosine 5′-diphosphate (and similarly for cytidine, guanosine, inosine, uridine, xanthosine, thymidine)
acquired immunodeficiency syndrome
adenosine 5′-phosphate etc.
adenosine 5′-triphosphate etc.
adenosine 5′-triphosphatase etc.
bovine serum albumin
cyclic AMP (adenosine 3′:5′-cyclic monophosphate) etc.
deoxyribonuclic acid, complementary DNA
enzyme-linked immunosorbent assay
fluorescence-activated cell sorting
fast protein liquid chromatography
guanine-nucleotide-binding regulatory protein
human immunodeficiency virus
high-performance liquid chromatography
immunoglobulin G etc.
NADH oxidized and reduced nicotinamide-adenine dinucleotide
NADPH oxidized and reduced nicotinamide-adenine dinucleotide phosphate
polymerase chain reaction
RNA, mRNA, hnRNA, rRNA, tRNA
ribonucleic acid, messenger RNA, hetero-nuclear RNA, ribosomal RNA, transfer RNA
sodium dodecyl sulphate
Nucleic acids - use one-letter symbol for ribonucleotides; 2′-deoxyribonucleotides are designated by the same symbol preceded by d, e.g. dG, 2′-deoxyribosylguanosine.
Symbols of genes and their cDNAs and RNAs should be italic; proteins are roman.
Amino acids - the three-letter symbol is preferred to the one-letter symbol.