Development of PCR primers enabling the design of flexible sticky ends for efficient concatenation of long DNA fragments

We developed chemically modified PCR primers that allow the design of flexible sticky ends by introducing a photo-cleavable group at the phosphate moiety. Nucleic acid derivatives containing o-nitrobenzyl photo-cleavable groups with a tert-butyl group at the benzyl position were stable during strong base treatment for oligonucleotide synthesis and thermal cycling in PCR reactions. PCR using primers incorporating these nucleic acid derivatives confirmed that chain extension reactions completely stopped at position 1 before and after the site of the photo-cleavable group was introduced. DNA fragments of 2 and 3 kbp, with sticky ends of 50 bases, were successfully concatenated with a high yield of 77%. A plasmid was constructed using this method. Finally, we applied this approach to construct a 48.5 kbp lambda phage DNA, which is difficult to achieve using restriction enzyme-based methods. After 7 days, we were able to confirm the generation of DNA of the desired length. Although the efficiency is yet to be improved, the chemically modified PCR primer offers potential to complement enzymatic methods and serve as a DNA concatenation technique.

The effect of γ phosphate modified deoxynucleotide substrates on PCR activity and fidelity

Controlling PCR fidelity is an important issue for molecular biology and high-fidelity PCR is essential for gene cloning. In general, fidelity control is achieved by protein engineering of polymerases. In contrast, only a few studies have reported controlling fidelity using chemically modified nucleotide substrates. In this report, we synthesized nucleotide substrates possessing a modification on Pγ and evaluated the effect of this modification on PCR fidelity. One of the substrates, nucleotide tetraphosphate, caused a modest decrease in Taq DNA polymerase activity and the effect on PCR fidelity was dependent on the type of mutation. The use of deoxyadenosine tetraphosphate enhanced the A:T→G:C mutation dramatically, which is common when using Taq polymerase. Conversely, deoxyguanosine tetraphosphate (dG4P) suppressed this mutation but increased the G:C→A:T mutation during PCR. Using an excess amount of dG4P suppressed both mutations successfully and total fidelity was improved.

P-027 which is the best method of testicular sperm retrieval for NOA? an answer from 1071 TESE cases in my clinics over 25 years

Study question

Which improves sperm recovery rate (SRR) for men with non-obstructive azoospermia (NOA), microdissection TESE (m-TESE) or conventional TESE (c-TESE)?

Summary answer

SRR of c-TESE vs. m-TESE for NOA was not significant. We need to develop a safer, less-invasive technique with fewer complications and higher SRR.

What is known already

m-TESE has been performed for men with NOA since Schlegel P’s report (Hum Reprod, 1999). Seminiferous tubules containing many developing germ cells were likely to be larger and more opaque and the ability to find spermatozoa increased from 45% (10/22) to 63% (17/27) after introduction of the microdissection technique. However, Jarvis S et al. (Turek PG group, 2019) reported that at least one site revealed mature sperm in 24 (29.3%) of 82 men with prior failed micro TESE procedures, and sperm were more likely to be found in the testis periphery rather than centrally with FNA mapping.

Study design, size, duration

TESE was performed in 1071 azoospermic patients in my clinics; c-TESE was performed for all azoospermic patients between 1996 and 2005 in Sendai; c-TESE for OA and m-TESE for NOA was performed from 2006 in Sendai, and from 2012 in Takanawa. The patients were divided into four groups; 1) FSH≦9.2mIU/ml, Testicular volume(TV)≧15/ml (OA), 2) FSH≦9.2mIU/ml, TV < 15ml, 3) FSH>9.2mIU/ml, TV≧15ml, 4) FSH>9.2mIU/ml, TV < 15ml (NOA).

Participants/materials, setting, methods

c-TESE was performed in 178 azoospermic men (50, 12, 7, 109, respectively) in 1996-2005. c-TESE was performed in 181 patients (131, 26, 15, 9, respectively) and m-TESE was performed in 541 patients (56, 33, 35, 416, respectively) in 2006 -2020. SRR, pregnancy rate (PR), and birth rate (BR) in 1996-2005 were compared with those in 2006-2020.

Main results and the role of chance

Statistical analysis was performed by chi-square analysis. SRR in c-TESE was 96.0% (48/50) in group 1 (OA) vs. 36.7% (40/109) in group 4 (NOA) in Sendai between 1996 and 2005 (P < 0.001).

SRR of c-TESE was 36.7% (40/109) in group 4 (NOA, in Sendai, 1996-2006), whereas SRR of m-TESE was 31.3% (130/416) in group 4 (NOA, in Sendai and Takanawa, 2006-2020). There was no significant difference (np).

Total SRR of conventional TESE for all azoospermic patients between 1996 and 2005 was 54.9% (96/175), whereas total SRR of c-TESE for OA and m-TESE for NOA between 2006 and 2020 was 51.7% (373/721). NOA rate 4) of azoospermic patients of 1996-2005 and that of 2006-2020 was 61.2% (109/178) and 58.9% (425/721), respectively. There was no significant difference (np).

PR was 37.4% (61/163) and BR was 31.9% (52/263) in c-TESE (1996-2005), PR was 39.6% (388/980), and BR was 27.6% (270//980) in both c-TESE and m-TESE (2006–2020). There was a significant difference in birth rate (P < 0.05).

In conclusion, SRR, PR, and BR were not improved even after m-TESE was performed. Considering the fact that m-TESE cannot find sperm thoroughly, adopting other techniques such as sperm fine-needle aspiration may be required.

Limitations, reasons for caution

Not applicable.

Wider implications of the findings

We could not show the effectiveness of m-TESE compared with c-TESE. However, the total volume of seminiferous tubules collected by c-TESE was the higher. The new one-step fine-needle aspiration has the potential to achieve higher sperm yield with fewer complications. Further advanced technology will hopefully improve the SRR in NOA.

Trial registration number

none

P-441 a study in status of use and live birth rates of cryopreserved oocyte for social reasons

Study question

What is status of use and live birth rates of cryopreservation oocyte for social reasons?

Summary answer

11.2% of the cryopreserved oocytes were warmed and transferred, and the oldest of the successful live birth was 39 years old.

What is known already

More people nowadays tend to delay marriage and childbearing due to the social circumstances. It is now gradually known that the pregnancy rate decreases with increasing age, since the donation of gametes from third parties is regulated by the Japanese society, oocyte cryopreservation for social reasons has been becoming common practice. However, not much is known about the subsequent pregnancy and childbirth. Therefore, we conducted a survey on the use and clinical outcomes of cryopreserved oocytes for social reasons in our clinic.

Study design, size, duration

This retrospective single-center study was conducted with a total of 285 women, 424 cycles from March 2014 to December 2019. A total of 2696 oocytes were cryopreserved by vitrification. Written informed consent was obtained from all women who participated in this study.

Participants/materials, setting, methods

Ovarian stimulation was performed mainly with GnRH antagonist protocol. An injection of 5000IU of HCG was administered when the diameter of dominant follicle reached 18mm. All oocytes were denuded enzymatically with 80 IU/ml hyaluronidase, followed by mechanical denudation. The oocytes were then evaluated at metaphase II by confirming the presence of the first polar body. Mature oocytes were cryopreserved by vitrification. The partner's sperm was injected into the vitrified-warmed oocytes.

Main results and the role of chance

The age groups in the first freezing cycle were 30-34 years (7.4%), 35-39 years (49.8%), 40-44 years (37.2%), and 45 years and older (5.6%), respectively. The mean number of OPU cycles was 1.1±0.4, 1.4±1.4, 1.5±1.1, and 1.7±1.7. The average number of retrieved oocytes was 9.5 ± 5.4, 7.3 ± 4.5, 5.6 ± 4.6, and 2.2 ± 2.2. The total number of cryopreserved oocytes was 10.4±5.9, 10.4±7.1, 8.8±6.8, and 3.3±3.4. Sixty-seven women had partners after oocyte cryopreservation, and 33 women (49.3%) had oocytes thawed. The mean age at oocytes freezing was 39.6±2.6 years, and the mean age at thawing was 42.2±2.5 years. The oocytes survival rates, fertilization rates, blastocyst rates and clinical pregnancy rates per embryo transferred of vitrified oocytes were 92.7% (328/354), 69.5% (228/328), 43.9% (87/198) and 31.1% (19/61), respectively. Of these, 15 women (45.5%) became pregnant with vitrified-warmed oocytes, and 10 (30.3%) had livebirth. 18 women did not become pregnant with vitrified-warmed oocytes. Subsequently, 3 of the 18 women then became pregnant in ART (5.6%), by IUI (5.6%), or spontaneously (5.6%), respectively.

Limitations, reasons for caution

Not applicable.

Wider implications of the findings

Of the 33 cases, 10 (30.3%) successfully gave birth, indicating the usefulness of oocyte cryopreservation for social reasons. However, considering that most of our patients were already around 40 years old, awareness of the benefits of oocytes cryopreservation at younger ages and education of reproductive health and rights is essential.

Trial registration number

none

Synthesis of Truncated Carbocyclic Nucleosides Using 5'-Deoxy-5'-Heteroarylsulfonylnucleosides

This article describes the detailed protocol for the synthesis of "truncated" carbocyclic nucleosides with a cyclopentene core and without a 4'-hydroxymethyl group. The synthesis was performed using 5'-deoxy-5'-heteroarylsulfonylnucleosides, which were prepared by the 5'-O-mesylation of the appropriately protected nucleosides, followed by a nucleophilic substitution with heteroarylthiols and the oxidation of the resulting 5'-S-heteroaryl-5'-thionucleosides. The treatment of the 5'-deoxy-5'-heteroarylsulfonylnucleosides with 1,8-diazabicyclo[5.4.0]undec-7-ene affords the truncated carbocyclic nucleosides, presumably via a domino reaction involving the α-deprotonation of the heteroarylsulfone, elimination of the nucleobase, formation of an α,β-unsaturated sulfone, Michael addition of the nucleobase to the α,β-unsaturated sulfone, and an intramolecular Julia-Kocienski reaction. This protocol would be useful for the short-step synthesis of biologically active carbocyclic nucleosides. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Preparation of 5'-deoxy-5'-heteroarylsulfonylnucleosides Basic Protocol 2: Synthesis of truncated carbocyclic nucleosides.

Serendipitous One-Step Synthesis of Cyclopentene Derivatives from 5'-Deoxy-5'-heteroarylsulfonylnucleosides as Nucleoside-Derived Julia-Kocienski Reagents

A serendipitous one-step transformation of 5'-deoxy-5'-heteroarylsulfonylnucleosides into cyclopentene derivatives is reported. This unique transformation likely proceeds via a domino reaction initiated by α-deprotonation of the heteroaryl sulfone and subsequent elimination reaction to generate a nucleobase and an α,β-unsaturated sulfone that contains a formyl group. The Michael addition of the nucleobase to the α,β-unsaturated sulfone and the subsequent intramolecular Julia-Kocienski reaction eventually generate the cyclopentene ring. Heteroarylthio and acylthio groups can be incorporated into the cyclopentene core in place of the nucleobase by conducting this reaction in the presence of a heteroarylthiol and a thiocarboxylic acid, respectively. cis,cis-Trisubstituted cyclopentene derivatives are obtained as a single stereoisomer from ribonucleoside-derived Julia-Kocienski sulfones.

Synthesis of xanthosine 2-phosphate diesters via phosphitylation of the carbonyl group

O²-Phosphodiesterification of xanthosine has been achieved by a one-pot procedure consisting of the phosphitylation of the 2-carbonyl group of appropriately protected xanthosine derivatives using phosphoramidites and N-(cyanomethyl)dimethylammonium triflate (CMMT), oxidation of the resulting xanthosine 2-phosphite triesters, and deprotection. In addition, a study on the hydrolytic stability of a fully deprotected xanthosine 2-phosphate diester has revealed that it is more stable at higher pH.

Stereoselective Synthesis of Ribofuranoid exo-Glycals by One-Pot Julia Olefination Using Ribofuranosyl Sulfones

One-pot Julia olefination using ribofuranosyl sulfones is described. The α-anomers of the ribofuranosyl sulfones were synthesized with complete α-selectivity via the glycosylation of heteroarylthiols using ribofuranosyl iodides as glycosyl donors and the subsequent oxidation of the resulting heteroaryl 1-thioribofuranosides with magnesium monoperphthalate (MMPP). The Julia olefination of the α-ribofuranosyl sulfones with aldehydes proceeded smoothly in one pot to afford the thermodynamically less stable (E)-exo-glycals with modest-to-excellent stereoselectivity (up to E/Z = 94:6) under the optimized conditions. The E selectivity was especially high for aromatic aldehydes. In contrast, the (Z)-exo-glycal was obtained as the main product with low stereoselectivity when the corresponding β-ribofuranosyl sulfone was used (E/Z = 41:59). The remarkable impact of the anomeric configuration of the ribofuranosyl sulfones on the stereoselectivity of the Julia olefination has been rationalized using density functional theory (DFT) calculations. The protected ribose moiety of the resulting exo-glycals induced completely α-selective cyclopropanation on the exocyclic carbon-carbon double bond via the Simmons-Smith-Furukawa reaction. The 2-cyanoethyl group was found to be useful for the protection of the exo-glycals, as it could be removed without affecting the exocyclic C═C bond.

Anti-allergic effect of the Src family kinase inhibitor saracatinib

The aim of this study was to evaluate the anti-anaphylactic and anti-allergic potentials of saracatinib, a Src family kinase inhibitor that was already shown to be safe in clinical trials when it was used as an anti-cancer drug. Using in vitro mast cell models, we found that saracatinib inhibited the degranulation response and cytokine production in RBL2H3 cells that were stimulated with IgE and antigen without affecting cell viability. Phosphorylation of Lyn, Akt, a PI3K substrate, and MAPKs including ERK, JNK, and p38, as well as the intracellular Ca²⁺ increase induced by this stimulation were also suppressed by saracatinib. This drug also inhibited symptoms in our established anaphylaxis mouse model, anaphylaxis-dependent spotted distribution of immune complex in skin (ASDIS). The intravenous injection of the mixture of IgE and antigen induced acute spotted distribution of immune complex in skin in hairless HR-1 mice, and its inhibition by intradermal injection of saracatinib was observed. Moreover, toluidine blue-stained skin sections indicated that the degranulation ratio of dermal mast cells was reduced in saracatinib-treated skin compared with vehicle-treated skin. Because only a few signaling inhibitors are used as anti-anaphylaxis and anti-allergic drugs, these results indicated the valuable suggestion that saracatinib and the Src family kinase inhibitors are good candidates for anti-anaphylaxis and anti-allergic drugs.

Enhancement of the affinity of 2′-O-Me-oligonucleotides for complementary RNA by incorporating a stereoregulated boranophosphate backbone

P-stereodefined boranophosphate 2′-O-Me-oligoribonucleotides (2′-O-Me-PB-ORNs) were synthesized and we revealed that an all-(Sp)-PB-backbone largely stabilized the duplex with RNA.

Search for bosonic superweakly interacting massive dark matter particles with the XMASS-I detector

Bosonic superweakly interacting massive particles (super-WIMPs) are a candidate for warm dark matter. With the absorption of such a boson by a xenon atom, these dark matter candidates would deposit an energy equivalent to their rest mass in the detector. This is the first direct detection experiment exploring the vector super-WIMPs in the mass range between 40 and 120 keV. With the use of 165.9 day of data, no significant excess above background was observed in the fiducial mass of 41 kg. The present limit for the vector super-WIMPs excludes the possibility that such particles constitute all of dark matter. The absence of a signal also provides the most stringent direct constraint on the coupling constant of pseudoscalar super-WIMPs to electrons. The unprecedented sensitivity was achieved exploiting the low background at a level 10(-4)  kg-1 keVee-1 day-1 in the detector.

Synthesis of inosine 6-phosphate diesters via phosphitylation of the carbonyl oxygen

Inosine derivatives bearing a phosphodiester group at the O(6)-position of the nucleobase were synthesized via phosphitylation of the carbonyl oxygen using phosphoramidites activated by non-nucleophilic acidic activators.

Solid-phase synthesis of P-boronated oligonucleotides by the H-boranophosphonate method

Recently, P-boronated oligonucleotides have been attracting much attention as potential therapeutic oligonucleotides. In this study, we developed H-boranophosphonate oligonucleotide bearing a borano group and hydrogen atom on the internucleotidic phosphorus and demonstrated that this novel P-boronated oligonucleotide is a versatile precursor to various P-boronated oligonucleotides such as boranophosphate, boranophosphorothioate, and boranophosphoramidate. The method was also applicable to the synthesis of a locked nucleic acid-modified boranophosphate oligonucleotide, which exhibited a dramatically enhanced affinity to complementary oligonucleotides.

Purification and comparison of native and recombinant tRNA-guanine transglycosylases from Methanosarcina acetivorans

Many archaeal tRNAs have archaeosine (G(+)) at position 15 in the D-loop and this is thought to strengthen the tertiary interaction with C48 in the V-loop. In the first step of G(+) biosynthesis, archaeosine tRNA-guanine transglycosylase (ArcTGT)(1) catalyzes the base exchange reaction from guanine to 7-cyano-7-deazaguanine (preQ(0)). ArcTGT is classified into full-size or split types, according to databases of genomic information. Although the full-size type forms a homodimeric structure, the split type has been assumed to form a heterotetrameric structure, consisting of two kinds of peptide. However, there has been no definitive evidence for this presented to date. Here, we show that native ArcTGT could be isolated from Methanosarcina acetivorans and two peptides formed a robust complex in cells. Consequently, the two peptides function as actual subunits of ArcTGT. We also overexpressed recombinant ArcTGT in Escherichia coli cells. Product was successfully obtained by co-overexpression of the two subunits but one subunit alone was not adequately expressed in soluble fractions. This result suggests that interaction between the two subunits may contribute to the conformational stability of split ArcTGT. The values of the kinetic parameters for the recombinant and native ArcTGT were closely similar. Moreover, tRNA transcript with preQ(0) at position 15 was successfully prepared using the recombinant ArcTGT. This tRNA transcript is expected to be useful as a substrate for studies seeking the enzymes responsible for G(+) biosynthesis.

Excitation Energy-Transfer Dynamics of Brown Algal Photosynthetic Antennas

Fucoxanthin-chlorophyll-a/c protein (FCP) complexes from brown algae Cladosiphon okamuranus TOKIDA (Okinawa Mozuku in Japanese) contain the only species of carbonyl carotenoid, fucoxanthin, which exhibits spectral characteristics attributed to an intramolecular charge-transfer (ICT) property that arises in polar environments due to the presence of the carbonyl group in its polyene backbone. Here, we investigated the role of the ICT property of fucoxanthin in ultrafast energy transfer to chlorophyll-a/c in brown algal photosynthesis using femtosecond pump-probe spectroscopic measurements. The observed excited-state dynamics show that the ICT character of fucoxanthin in FCP extends its absorption band to longer wavelengths and enhances its electronic interaction with chlorophyll-a molecules, leading to efficient energy transfer from fucoxanthin to chlorophyll-a.

Stereocontrolled solid-phase synthesis of phosphorothioate oligoribonucleotides using 2'-O-(2-cyanoethoxymethyl)-nucleoside 3'-O-oxazaphospholidine monomers

A method for the synthesis of P-stereodefined phosphorothioate oligoribonucleotides (PS-ORNs) was developed. PS-ORNs of mixed sequence (up to 12mers) were successfully synthesized by this method with sufficient coupling efficiency (94-99%) and diastereoselectivity (≥98:2). The coupling efficiency was greatly improved by the use of 2-cyanoethoxymethyl (CEM) groups in place of the conventional TBS groups for the 2'-O-protection of nucleoside 3'-O-oxazaphospholidine monomers. The resultant diastereopure PS-ORNs allowed us to clearly demonstrate that an ORN containing an all-(Rp)-PS-backbone stabilizes its duplex with the complementary ORN, whereas its all-(Sp)-counterpart has a destabilizing effect.

Trimethylsilyl trifluoromethanesulfonate-promoted reductive 2'-O-arylmethylation of ribonucleoside derivatives

Arylmethyl groups such as benzyl, p-methoxybenzyl, and 1-pyrenylmethyl groups were introduced to the 2'-O-position of nucleosides by reductive etherification. Combining corresponding aromatic aldehydes with 2'-O-trimethylsilylnucleoside derivatives in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) resulted in moderate to good yields of the 2'-O-arylmethyluridine derivatives, whereas the corresponding cytidine and adenosine derivatives were obtained in low yields. The reaction of ribonucleosides with aliphatic aldehydes did not proceed smoothly. Anomerization of the uridine derivatives by TMSOTf was observed in CH(2)Cl(2), toluene, and CH(3)CN, but was completely suppressed when the reactions were conducted in 1,4-dioxane.

Stereocontrolled synthesis of oligonucleotide analogs containing chiral internucleotidic phosphorus atoms

Oligonucleotides, in which one of the two nonbridging oxygen atoms of internucleotidic phosphates is replaced by a different type of atom or a substituent, are useful as therapeutic agents and probes to elucidate mechanisms of enzymatic reactions. The internucleotidic phosphorus atoms of these oligonucleotides are chiral, and the properties of these oligonucleotides are affected by the absolute configuration of the chiral phosphorus atoms. In order to address the issue of chirality, various methods have been developed to synthesize these P-chiral oligonucleotide analogs in a stereocontrolled manner. This critical review focuses on the recent progress in this field (123 references).

Stereocontrolled synthesis of oligonucleoside phosphorothioates and PO/PS-chimeric oligonucleotides by using oxazaphospholidine derivatives

Solid-phase synthesis of oligonucleotides having a fully-modified stereoregular phosphorothioate backbone or a stereoregular phosphate/phosphorothioate chimeric backbone was achieved by using diastereopure nucleoside 3'-bicyclic oxazaphospholidine derivatives and beta-cyanoethyl phosphoramidites as monomer units and N-(cyanomethyl)pyrrolidinium trifluoromethanesulfonate (CMPT) as an acidic activator. The trans-isomers of the oxazaphospholidines were obtained exclusively by the reaction of the 3'-OH of appropriately protected nucleosides and the corresponding 2-chloro-1,3,2-oxazaphospholidine derivative. The trans-isomers were configurationally stable and did not epimerize almost at all even in the presence of CMPT. As a result, the formation of phosphorothioate internucleotide linkages using the oxazaphospholidine derivatives and CMPT proceeded without any loss of diastereopurity. In addition to the synthesis of stereoregular phosphorothioate linkages, the synthesis of phosphate internucleotide linkages through the same method was studied. As a result of the study, stereoregular phosphate/phosphorothioate chimeric oligonucleotides as well as stereoregular oligonucleoside phosphorothioates were efficiently synthesized by using the same method.

Stereocontrolled synthesis of backbone-modified oligonucleotides via diastereopure H-phosphonate intermediates

Synthesis of stereoregulated backbone-modified oligodeoxyribonucleotides via the corresponding diastereopure H-phosphonate intermediates is described. The diastereopure H-phosphonate intermediates were synthesized by using the nucleoside 3'-oxazaphospholidine monomers, and were stereospecifically converted into a variety of P-stereoregulated backbone-modified oligonucleotides, such as phosphorothioates, boranophosphates, and phosphoramidates, on a solid-support.

Solid-phase synthesis of oligodeoxyribonucleotides without base protection utilizing O-selective reaction of oxazaphospholidine derivatives

A study on the development of a novel method to synthesize oligodeoxyribonucleotides without base protection is described. We found that nucleoside 3'-O-oxazaphospholidine derivatives exclusively react with the hydroxy group of nucleosides in the presence of unprotected nucleobase amino groups. Since the O-chemoselectivity of the oxazaphospholidine derivatives is likely due to their ring structure, which allows the regeneration of the oxazaphospholidine derivatives from the corresponding base phosphitylation adducts via an intramolecular recyclization, the method is expected to be compatible with any kinds of acidic activators.

Synthesis and biological activity of artificial mRNA prepared with novel phosphorylating reagents

Though medicines that target mRNA are under active investigation, there has been little or no effort to develop mRNA itself as a medicine. Here, we report the synthesis of a 130-nt mRNA sequence encoding a 33-amino-acid peptide that includes the sequence of glucagon-like peptide-1, a peptide that stimulates glucose-dependent insulin secretion from the pancreas. The synthesis method used, which had previously been developed in our laboratory, was based on the use of 2-cyanoethoxymethyl as the 2′-hydroxy protecting group. We also developed novel, highly reactive phosphotriester pyrophosphorylating reagents to pyrophosphorylate the 5′-end of the 130-mer RNA in preparation for capping. We completed the synthesis of the artificial mRNA by the enzymatic addition of a 5′-cap and a 3′-poly(A) tail to the pyrophosphorylated 130-mer and showed that the resulting mRNA supported protein synthesis in a cell-free system and in whole cells. As far as we know, this is the first time that mRNA has been prepared from a chemically synthesized RNA sequence. As well as providing a research tool for the intracellular expression of peptides, the technology described here may be used for the production of mRNA for medical applications.