Electronic files (electronic backup and e-mail submission) should be in MS Word for text and TIFF/JPEG/EPS/PDF for figures. E-mail submissions involving multiple large files, may need to be sent in separate messages.

Preparation
The text should be provided as an MS Word file. Manuscripts should be typed in English, double spaced and on single-sided A4 paper, and should be numbered beginning with the title page. Research papers should be divided into Abstract (up to 200 words), Introduction, Materials and Methods, Results, Discussion, Acknowledgments and References. The first page of the article should contain only (1) the title of the paper, name(s) and address(es) of the author(s); (2) 4 - 6 key words for indexing purposes; (3) a short title not exceeding 45 letters and spaces (which will be used for page headlines); and (4) the name and address of the author to whom correspondence and electronic galley proofs (full-color PDF) should be sent.

Tables and figures
Tables should be given short informative titles and should be numbered consecutively in Arabic numerals. Tables must be typed on separate sheets and/or provided as individual files. Figures in a form suitable for reproduction should be submitted separately from the text as electronic files (TIFF, JPEG, EPS or PDF). Lettering on figures should be proportional to the size of the figure to ensure legibility after reduction (the final printed size of figures will not exceed 5" × 7.6"/12.7 cm × 19.5 cm). For airmail submissions, electronic files should be sent along with the hardcopy (e.g. drawings in Indian ink, or high contrast, sharp unmounted photographs on glossy paper, about twice the desired size). On the back of each figure should be indicated lightly in soft pencil: (1) the top of the figure with an arrow; (2) the figure number and the author's name. All the figures and tables should be cited consecutively in the text and a list of short figure captions should be provided at the end of the paper.

Color figures are welcome, in particular for the online edition of the journal. They are published free of charge in the online edition of the journal as well as on the website of the Publisher, even if they are printed in black and white in the print edition of the journal. On the other hand, a contribution towards the cost of reproduction of color figures is requested for the print edition: US$200 or each published page of color figure(s).

References
The Harvard system should be used for the references. In this system, names and dates are given in the body of the text and an alphabetical list of references at the end of the manuscript. References in the text should give the author's surname and the year of publication, in parentheses. When a reference is made to a work by two authors, both names should be given; references to works by more than two authors should give the name of the first author, followed by et al., e.g.: (Smith et al., 1973). If several papers by the same author(s) in the same year are cited, a, b, c, etc. should be placed after the year of publication, e.g.: (Smith and Jones, 1982a & 1982b).

References style
References to articles from journals contain the following items in the order listed: name(s) of author(s), year of publication in parentheses, full title of the article, title of the periodical, volume number, first and last relevant page numbers, e.g.:

Jackson DA, Symons RH and Berg P. (1972). Biochemical method for inserting new genetics information into DNA of Simian virus 40: circular SV40 DNA molecules containing lambda phage genes and the galactose operon of Escherichia coli. Proc Natl Acad Sci USA 69: 2904-2909.

References to articles from books (or to whole books) should give the following order: name(s) of author(s), year of publication in parentheses, full title of the article, title of the book (volume number if applicable), initials followed by name(s) of the editor(s), name and location of the publisher, and first and last relevant page numbers, e.g.:

Temin HM. (1986). Retrovirus vectors for gene transfer: efficient integration into and expression of exogenous DNA in vertebrate cell genomes. In: Gene Transfer, R. Kucherlapati (ed.), Plenum Press, New York, pp. 149-187.

If a publication is in press, the reference should be made as complete as possible, stating the name of the journal and adding "in press". The list of references should be typed with double spacing and in alphabetical order of the first author's name. When a number of publications by the same author are cited, the order should be (1) single-author references in date order, (2) two-authored references in alphabetical order of the second author, and (3) et al. references in date order.

Reprints
First-named authors may opt to receive either 25 offprints of their respective articles free of charge or a complimentary PDF file of the article for personal use. Additional reprints may be ordered at prices shown on the Offprint Order Form, which will be sent to the author together with the electronic galley proofs.