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Genome Res. 13:1488-1495, 2003 ©2003 by Cold Spring Harbor Laboratory Press; ISSN 1088-9051/03 $5.00 Methods DNA Book1Laboratory for Genome Exploration Research Group, RIKEN Genomic Sciences Center (GSC), RIKEN Yokohama Institute, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan 2Genome Science Laboratory, RIKEN, Hirosawa, Wako, Saitama, 351-0198, Japan
We propose herein a new method of DNA distribution, whereby DNA clones or PCR products are printed directly onto the pages of books and delivered to users along with relevant scientific information. DNA sheets, comprising water-soluble paper onto which DNA is spotted, can be bound into books. Readers can easily extract the DNA fragments from DNA sheets and amplify them using PCR. We show that DNA sheets can withstand various conditions that may be experienced during bookbinding and delivery, such as high temperatures and humidity. Almost all genes (95%100% of randomly selected RIKEN mouse cDNA clones) were recovered successfully by use of PCR. Readers can start their experiments after a 2-h PCR amplification without waiting for the delivery of DNA clones. The DNA Book thus provides a novel method for delivering DNA in a timely and cost-effective manner. A sample DNA sheet (carrying RIKEN mouse cDNA clones encoding genes of enzymes for the TCA cycle) is included in this issue for field-testing. We would greatly appreciate it if readers could attempt to extract DNA and report the results and whether the DNA sheet was shipped to readers in good condition.
Developing genome technologies allows the continued elucidation of the genomes of many species, including human and mouse (International Human Genome Sequencing Consortium 2001
RIKEN has been constructing the Mouse Genome Encyclopedia to establish an infrastructure for functional genomics. The Mouse Genome Encyclopedia is a comprehensive collection of the mouse transcriptome comprising (1) a full set of mouse full-length cDNA clones, (2) nucleotide sequences of clones, and (3) functional annotation of clones. To achieve this goal, RIKEN has developed a series of full-length cDNA technologies (Carninci and Hayashizaki 1999
Currently, the Internet allows wide and simple transfer and distribution of scientific information, including nucleotide sequences and gene annotation, as well as scientific papers. The RIKEN FANTOM database of sequences and annotation has been released and is accessible through the Internet (http://fantom2.gsc.riken.go.jp/ In addition, organizations that constitutively distribute DNA clone resources from genome and transcriptome science must demonstrate the following characteristics: (1) establishment of an economical basis for autonomous activity; (2) ability to handle legal issues such as intellectual property rights; and (3) technologies for resource distribution. However, as mentioned above, traditional protocols for clone distribution do not fulfill the recent requirements for DNA clone distribution produced by transcriptome analysis. To improve this situation, we propose a novel concept of DNA distributionthe DNA Book. If the sheets on which DNA clones or PCR products are printed are attached to the pages of books and journals, DNA could be delivered to users along with the relevant scientific articles and information. Researchers could easily extract and use this DNA for their own experiments. The DNA Book offers the following advantages: (1) simultaneous delivery of scientific information and associated DNA clones or PCR products themselves; (2) easy extraction of DNA using PCR; (3) a cheap method of DNA distribution; and (4) stable preservation in the laboratory environment.
The present work describes the feasibility of DNA sheets and the DNA Book according to the results of various tests. In addition, we have bound one DNA sheet into this issue as a sample. The final aim of this study is to conduct a field test of the DNA Book. We are eager to learn whether the DNA attached to the page can be amplified successfully when the DNA Book is received by readers worldwide. We would very much appreciate if readers could try to extract the DNA and report the results to our Web page, http://genome.gsc.riken.go.jp/DNA-Book/
Figure 1 shows the concept behind the DNA Book. Papers are printed as usual, with letters and figures describing genetic research in the conventional way. DNA solutions are then spotted at defined positions on the same sheet of paper. The DNA sheets are bound into the book or journal and delivered to readers through bookstores or by courier as printed matter. Researchers, students, and readers who are interested in the enclosed genes can extract, amplify, and immediately apply DNA from the sheets to their research. To produce the DNA Book, several issues must be considered. (1) DNA should be extractable by readers easily, with a high success rate; (2) DNA on the sheets should be able to be preserved in a stable form during bookbinding and shipping; and (3) costs should not be expensive. Either the cDNA clones or PCR fragments of cDNA could be used for DNA printing onto sheets. In the Results section, we show the data based on the use of full-length cDNAs for DNA printing. In practical use, PCR fragments are also recommended as suitable materials to be printed.
Producing DNA Sheets and DNA Extraction Plasmid DNA solutions were transferred onto 60MDP paper using a 96-pin tool (Multi 96-multiblot replicator), which was originally designed for the creation of high-density filters, and allowed us to spot defined amounts of DNA solution onto specific positions on the paper. Spotted positions can be identified easily by use of a red dye mixed in the DNA solution. We used 0.05 microG of DNA solution for each spot. After drying the paper in air for more than 30min, we extracted DNA from the sheet using the following method. The piece of 60MDP paper (4 mm x 4 mm) containing the DNA spot was placed into a 0.2-mL PCR tube. We added 50 microL of PCR solution containing all of the necessary reagents (primers, polymerase, dNTPs, etc.), and initiated the PCR reaction as described in the Methods. We tested three RIKEN cDNA clones with various insert sizes (722, 2418, and 5438 bp). The cDNA inserts were amplified successfully at higher Mg2+ concentrations of around 5.3 mM (Fig. 2A). This result is consistent with the fact that 60MDP binds cations (Y. Ishino and Y. Kimura, unpubl.). The amount of DNA spotted on the paper should be at least 5 ng. Conditions for spotting and extracting DNA were thus established. In addition, we tested several other PCR conditions. A relatively small volume of PCR solution (25 microL) demonstrated reduced DNA amplification. Increased amounts of polymerase had no effect. Addition of BSA and DMSO did not improve the PCR reaction. Several other kinds of papers also can be used for the DNA sheets with optimized conditions (data not shown).
We also tested a higher density of DNA spots per unit area, as with a 384-well plate. Successful recovery of DNA by PCR was achieved without any contamination from neighboring DNAs. Furthermore, as an alternative, an aliquot of solution containing the dissolved DNA sheet can undergo either PCR in a separate tube or E. coli transformation. Readers can keep any remaining solution as backup or for other experiments. Please see the Methods section for a protocol of E. coli transformation. Users do not need to undertake any purification of DNA after dissolution of the DNA sheet, and can apply aliquots directly to transformation. Transformation efficiency from the DNA sheet is equivalent to the control plasmid (data not shown). When PCR errors must be avoided for downstream experiments such as protein expression, DNA recovery by E. coli transformation is recommended.
Success Rate of DNA Extraction
Preservation of DNA Sheets Next, we observed successful recovery of DNA from DNA sheets kept overnight under conditions of 70%100% humidity at 37°C. We tested whether rubbing stress on DNA sheets could cause problems, such as inhibition of PCR amplification, or cross-contamination with neighboring DNA. DNA sheets spotted with three kinds of cDNA plasmids were stored in a humidified incubator, or inserted into an issue of Genome Research and shaken strongly using a rotating shaker (180 rpm) at 37°C with 70% humidity for 14 h. DNA inserts were then extracted by PCR as described above. All DNA inserts (722, 2418, and 5438 bp) were recovered (Fig. 2C). No contamination of DNA spots with neighboring spots was observed. The 60MDP paper used here for the DNA sheet comprises two kinds of fibers, wood pulp and carboxyl-methyl cellulose (CMC). Water-soluble CMC allows 60MDP to dissolve in water and DNA might be incorporated and trapped by the CMC gel when spotted. In addition, CMC might be able to keep DNA bound tightly within the DNA sheet after drying, and thus prevent the release or transfer of spotted DNA.
DNA Sheet Sample and the Field Test In practical use, DNA Books are likely to be piled up in bookstore warehouses, and are sometimes thrown around during the delivery process. In these processes, mechanical sliding stress at high pressure is quite likely to be exerted on the surface of the DNA sheet. Although we have tested the tolerance of the DNA sheet to temperature, high pressure, humidity, and rubbing stress, it is still not equivalent to the full range of situations and conditions DNA sheets will encounter in practical use. Because publication of this work offers the best opportunity to test such parameters, we ask for readers' contributions to examine the practical use of DNA sheets by testing DNA amplification and sending data to us on our Web site. An actual test sample for the DNA sheet is included in Figure 3. Twelve DNA samples of RIKEN mouse cDNA clones, annotated as genes of the TCA cycle, (The FANTOM Consortium and The RIKEN Genome Exploration Research Group Phase I and II 2002
Figure 5 shows historical transitions in the role of printing media. In the pre-genome era of research for conventional molecular biology, printed materials, books, and journals, were the vehicles to convey information regarding genes and scientific research. Thus, printed matter can also carry sequence information (database). However, DNA clones were distributed as frozen transformants of E. coli and/or as DNAs. The amount of sequence information and number of DNA clones were small enough to be handled using such methods in the pre-genome research era. From the middle of the 1990s, development of high-throughput genome technology such as automated fluorescence sequencers allowed production of huge amounts of genome sequence information for various species. Genome sequence information started to be distributed worldwide via the Internet, allowing instantaneous dissemination of information. Transfer of genome sequence information in an electronic form through the Internet is extremely convenient for downstream research, as investigators had to search for and analyze large amounts of genomic information with the aid of the exponentially growing power of computers, following Moore's law. Furthermore, scientific publications have also started to be distributed over the Internet, utilizing the substantial advantages of rapid, worldwide dissemination and cost-effectiveness. These changes have rendered printed material less significant as a vehicle of information. Conversely, tubes and plates have remained in use as vehicles of distribution for DNA clones or PCR products, even after the advent of the genome era. Although the need for genomic DNA clones is growing, the number of users requesting such clones has so far stayed small enough for shipping by use of traditional methods to remain feasible. The reason is that genome sequences are much more frequently used than genomic clones, due to the design of current research in molecular biology.
However, the situation has started to undergo massive changes with the advent of the era of transcriptome research, wherein mRNA transcribed from genomes and cDNA synthesized in vitro represent the major targets of analysis examining gene function. Information obtained from cDNA analysis is essential to understanding the structures of transcriptomes and proteomes. The structure of mRNA, with starting points of transcription, splicing, and termination, and anti-sense RNA and protein noncoding RNA cannot yet be predicted exactly from genomic sequences using only bioinformatic tools such as exon prediction software. Furthermore, functional studies of genes such as comprehensive expression profiling with cDNA microarrays and determination of three-dimensional protein structures require physical cDNA. Systematic analysis of transcriptomes on the basis of full-length cDNA technology is producing a vast number of cDNA clones every day. Our group has actually developed full-length cDNAs and sequences for 60,770 mouse cDNA clones (FANTOM Consortium and The RIKEN Genome Exploration Research Group Phase I and II 2002 The DNA Book we describe herein represents a potential solution to this problem. The DNA Book is a paper-based vehicle for the transfer of genetic material, whereby DNA is attached to book pages and shipped together with the relevant scientific information. Clearly, the DNA Book has a strong potential to replace tubes or plates as a vehicle of DNA clones, and offers several advantages:
The DNA Book could be applied to a variety of situations. (1) For example, physical cDNA fragments can simply be printed onto standard textbooks of molecular biology. A comprehensive set of yeast genes
To establish the DNA Book, one problem remains to be addressed, namely the evaluation of stable preservation of the DNA Book. Although we have demonstrated that DNA sheets can tolerate conditions likely to be encountered during bookbinding and shipping (Fig. 2C), further testing is warranted. The final aim of this work is, therefore, to enlist the help of readers in a large-scale field-test of the DNA Book. We have attached a sample DNA sheet accompanying this article (Fig. 3). We would greatly appreciate readers' attempts to extract the genes printed on Figure 3, and feedback can be input on our Web page, http://genome.gsc.riken.go.jp/DNA-Book/
DNA Preparation for Printing and Spotting Plasmid DNA of RIKEN mouse cDNA was purified using a Qiagen Spin Miniprep Kit (QIAGEN) or the ultra-centrifugation method (Sambrook and Russell 2001 0.1 µL each) was taken by the VP409 96-multiblot replicator (Bio Medical Science), and placed on the target DNA sheet. DNA solution was spotted five times for each spot, for a total of about 0.5 µL (0.05 µg) of DNA. Letters and figures had been printed on the sheet prior to spotting the DNA. The 60MDP paper used for DNA sheets was kindly provided by Mishima Paper Co., Ltd. Alternatively, PCR fragments of cDNA can be used for printing. Thus, cDNA inserts were amplified from 1 ng of cDNA plasmids with KOD Plus DNA Polymerase (TOYOBO Co., Ltd.). PCR conditions were 1x KOD Plus PCR buffer, together with 0.2 µM of PCR primers (-21M13; 5'-TGTAAAACGACGGCCAGT-3', 1233-Rv; 5'-AGCGGATAACAATTTCACACAGGA-3') and 0.2 mM each of dATP, dGTP, dCTP, and dTTP. PCR cycles comprised 2 min at 94°C; 29 cycles of denaturing (94°C, 1 min), annealing (60°C, 1 min) and extension (68°C, 75 sec), and 15 min at 74°C. After purification by PEG precipitation, 50ng of PCR fragments can be spotted onto the DNA sheet as described above.
Sample DNA Sheet
Extraction and Recovery of DNAs
Alternatively, aliquots of dissolved-paper solution can be subjected to E. coli transformation. As described above, a piece of DNA sheet (
We thank Mitsue Nakamura, Noriko Yokota, Shinya Sawata, Koichi Imotani, Hisamichi Ogura, Akiko Tomotsugu, Tsugumi Kawashima, Shigeyasu Yoshida, and Ryo Ishimoto for their technical assistance, Kazuhiro Shibata, Masayoshi Itoh, and Hiromi Torigoe for their kind support, and Hidemasa Bono and Katsunaga Sakai for selection of TCA cycle genes. We also thank the Mishima Paper Co., Ltd. for kindly providing the water-soluble paper. This study was supported by a Research Grant for the RIKEN Genome Exploration Research Project from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government to Y.H.
Article and publication are at http://www.genome.org/cgi/doi/10.1101/gr.914203.
3 Corresponding authors. A sample DNA sheet, to which 12 RIKEN cDNA plasmids of TCA cycle genes have been attached, is bound to this article (Fig.3). Clone IDs (DDBJ accession numbers) are 1500012M15 (AK005237 [GenBank] ), 1500012E04 (AK117103 [GenBank] ), E03002 [GenBank] 4J03 (AK087063 [GenBank] ), E430020N12 (AK088582 [GenBank] ), 9430063I08 (AK034928 [GenBank] ), 6430550J24 (AK032458 [GenBank] ), 2610028K08 (AK117104 [GenBank] ), E230015D12 (AK054053 [GenBank] ), 1700007H16 (AK005713 [GenBank] ), 0610009E03 (AK002379 [GenBank] ), 9430071P19 (AK034998 [GenBank] ), and E430029P17 (AK088888 [GenBank] )
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http://fantom2.gsc.riken.go.jp/; FANTOM home page. http://genome.gsc.riken.go.jp/DNA-Book/; DNA Book home page.
Received October 16, 2002;
accepted in revised format April 8, 2003.
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