Gene Symbol: Hsp83
Description: Heat shock protein 83
Alias: 143198_at, 83K HSP, CG1242, DMHSP82, DmHsp83, Dmel\CG1242, E(sev)3A, E(sina)2, HSP82, HSP83, HSP90, HSP90A1, Hsp82, Hsp90, ORF1, P02828, Su(Raf)3A, anon-EST:Liang-2.53, anon-WO0068693, anon-WO0140519.209, clone 2.53, en(lz)3C/4C, hsp82, hsp83, hsp84, hsp90, l(3)j5C2, ms(3)08445, stc, heat shock protein 83, CG1242-PA, CG1242-PB, Hsp83-PA, Hsp83-PB, enhancer of seven in absentia 2, enhancer of sevenless 3A, heat-shock protein 90 kDa, scratch
Species: fruit fly

Top Publications

  1. McLaren A. Too late for the midwife toad: stress, variability and Hsp90. Trends Genet. 1999;15:169-71 pubmed
    ..Their results are also relevant to observations from the 1950s concerning homozygosity and variability, with a bearing on current views concerning the use of inbred strains. ..
  2. Lange B, Bachi A, Wilm M, Gonzalez C. Hsp90 is a core centrosomal component and is required at different stages of the centrosome cycle in Drosophila and vertebrates. EMBO J. 2000;19:1252-62 pubmed
    ..One of the proteins identified is Hsp83, a member of the highly conserved Hsp90 family including chaperones known to maintain the activity of many ..
  3. Arbeitman M, Hogness D. Molecular chaperones activate the Drosophila ecdysone receptor, an RXR heterodimer. Cell. 2000;101:67-77 pubmed
    ..We also show that two of the six (Hsp90 and Hsc70) are required in vivo for ecdysone receptor activity, and that EcR is the primary target of the ..
  4. Rutherford S. From genotype to phenotype: buffering mechanisms and the storage of genetic information. Bioessays. 2000;22:1095-105 pubmed
    ..Thus, buffering mechanisms modulate evolution and regulate a balance between evolutionary stasis and change. Recent work provides a glimpse of the molecular details governing some types of genetic buffering. ..
  5. Yahara I. The role of HSP90 in evolution. Genes Cells. 1999;4:375-9 pubmed
    ..without expressing phenotypes was unraveled by Rutherford & Lindquist (1998) through genetic studies of Hsp83 (HSP90) in Drosophila...
  6. Fujikake N, Nagai Y, Popiel H, Okamoto Y, Yamaguchi M, Toda T. Heat shock transcription factor 1-activating compounds suppress polyglutamine-induced neurodegeneration through induction of multiple molecular chaperones. J Biol Chem. 2008;283:26188-97 pubmed publisher
    ..17-AAG induced Hsp70, Hsp40, and Hsp90 expression in a dose-dependent manner, and the expression levels correlated with its therapeutic effects...
  7. van der Straten A, Rommel C, Dickson B, Hafen E. The heat shock protein 83 (Hsp83) is required for Raf-mediated signalling in Drosophila. EMBO J. 1997;16:1961-9 pubmed
    ..We have identified mutations in the hsp83 gene, the Drosophila homologue of hsp90, in a search for dominant mutations that attenuate signalling from Raf in ..
  8. Michaud S, Marin R, Tanguay R. Regulation of heat shock gene induction and expression during Drosophila development. Cell Mol Life Sci. 1997;53:104-13 pubmed
  9. Li J, Li W. Drosophila gain-of-function mutant RTK torso triggers ectopic Dpp and STAT signaling. Genetics. 2003;164:247-58 pubmed
    ..These results demonstrate an essential requirement of noncanonical signaling pathways for a persistently activated RTK to cause pathological defects in an organism. ..

More Information


  1. Buszczak M, Spradling A. The Drosophila P68 RNA helicase regulates transcriptional deactivation by promoting RNA release from chromatin. Genes Dev. 2006;20:977-89 pubmed
    ..Our observations reveal a strong connection between transcript clearance and gene repression. P68 may be needed to rapidly remove transcripts from a gene before its activity can be shut down and its chromatin reset to an inactive state. ..
  2. Sollars V, Lu X, Xiao L, Wang X, Garfinkel M, Ruden D. Evidence for an epigenetic mechanism by which Hsp90 acts as a capacitor for morphological evolution. Nat Genet. 2003;33:70-4 pubmed
    Morphological alterations have been shown to occur in Drosophila melanogaster when function of Hsp90 (heat shock 90-kDa protein 1alpha, encoded by Hsp83) is compromised during development...
  3. Goto S, Kimura M. Heat-shock-responsive genes are not involved in the adult diapause of Drosophila triauraria. Gene. 2004;326:117-22 pubmed
    ..Here, we investigated the transcriptional regulation of other heat-shock-responsive genes (Hsp23, Hsp26, Hsp83 and Hsrw) in D. triauraria with relation to diapause...
  4. Milton C, Huynh B, Batterham P, Rutherford S, Hoffmann A. Quantitative trait symmetry independent of Hsp90 buffering: distinct modes of genetic canalization and developmental stability. Proc Natl Acad Sci U S A. 2003;100:13396-401 pubmed
    The Hsp90 chaperone buffers development against a wide range of morphological changes in many organisms and in Drosophila masks the effects of hidden genetic variation...
  5. Morcillo G, Diez J, Carbajal M, Tanguay R. HSP90 associates with specific heat shock puffs (hsr omega) in polytene chromosomes of Drosophila and Chironomus. Chromosoma. 1993;102:648-59 pubmed
    The heat shock protein HSP90, which is mainly cytoplasmic, has recently been reported to be present in the nucleus...
  6. Rutherford S. Between genotype and phenotype: protein chaperones and evolvability. Nat Rev Genet. 2003;4:263-74 pubmed
    ..Environmentally sensitive chaperone functions in protein folding and signal transduction have different potential consequences for the evolution of populations and lineages under selection in changing environments. ..
  7. Xiao H, Lis J. Heat shock and developmental regulation of the Drosophila melanogaster hsp83 gene. Mol Cell Biol. 1989;9:1746-53 pubmed
    ..expression is normally at a very low level and increases by more than 2 orders of magnitude during heat shock, the hsp83 gene in Drosophila melanogaster is expressed at high levels during normal development and increases only ..
  8. Pelham H. A regulatory upstream promoter element in the Drosophila hsp 70 heat-shock gene. Cell. 1982;30:517-28 pubmed
    ..It seems that the upstream element of the hsp 70 promoter is analogous to that of other promoters, but is only functional in heat-shocked cells. ..
  9. Bashirullah A, Cooperstock R, Lipshitz H. Spatial and temporal control of RNA stability. Proc Natl Acad Sci U S A. 2001;98:7025-8 pubmed
    ..Similar mechanisms are likely to act later in development to restrict certain classes of transcripts to particular cell types within somatic cell lineages. Functions of transcript degradation and protection are discussed. ..
  10. Murawska M, Hassler M, Renkawitz Pohl R, Ladurner A, Brehm A. Stress-induced PARP activation mediates recruitment of Drosophila Mi-2 to promote heat shock gene expression. PLoS Genet. 2011;7:e1002206 pubmed publisher
    ..We suggest that stress-induced chromatin PARylation serves to rapidly attract factors that are required for an efficient and timely transcriptional response. ..
  11. Neal S, Karunanithi S, Best A, So A, Tanguay R, Atwood H, et al. Thermoprotection of synaptic transmission in a Drosophila heat shock factor mutant is accompanied by increased expression of Hsp83 and DnaJ-1. Physiol Genomics. 2006;25:493-501 pubmed
    ..Transcripts of the hsp83, dnaJ-1 (hsp40), and glutathione-S-transferase gstE1 genes were significantly upregulated in hsf4 larvae after ..
  12. Tritto P, Specchia V, Fanti L, Berloco M, D Alessandro R, Pimpinelli S, et al. Structure, regulation and evolution of the crystal-Stellate system of Drosophila. Genetica. 2003;117:247-57 pubmed
    ..In addition three autosomal mutations: sting, scratch and sirio are described that interfere with the system...
  13. Kaminker J, Singh R, Lebestky T, Yan H, Banerjee U. Redundant function of Runt Domain binding partners, Big brother and Brother, during Drosophila development. Development. 2001;128:2639-48 pubmed
    ..These studies highlight a mechanism for transcriptional control by a Runt Domain protein and a redundant pair of partners in the specification of cell fate during development. ..
  14. Xiao H, Lis J. Germline transformation used to define key features of heat-shock response elements. Science. 1988;239:1139-42 pubmed
    ..These and additional analyses indicate that the heat-shock regulatory element includes sequences beyond the 14-base pair HSE and may be better described as a dimer of a 10-base pair sequence, NTTCNNGAAN. ..
  15. Andrulis E, Guzman E, Döring P, Werner J, Lis J. High-resolution localization of Drosophila Spt5 and Spt6 at heat shock genes in vivo: roles in promoter proximal pausing and transcription elongation. Genes Dev. 2000;14:2635-49 pubmed
    ..These findings provide support for the roles of Spt5 in promoter-associated pausing and of Spt5 and Spt6 in transcriptional elongation in vivo. ..
  16. Rutherford S, Lindquist S. Hsp90 as a capacitor for morphological evolution. Nature. 1998;396:336-42 pubmed
    The heat-shock protein Hsp90 supports diverse but specific signal transducers and lies at the interface of several developmental pathways...
  17. Rutherford S, Henikoff S. Quantitative epigenetics. Nat Genet. 2003;33:6-8 pubmed
  18. Miyoshi T, Takeuchi A, Siomi H, Siomi M. A direct role for Hsp90 in pre-RISC formation in Drosophila. Nat Struct Mol Biol. 2010;17:1024-6 pubmed publisher
    ..Argonaute 2 (Ago2), the effector in RNA interference (RNAi), is associated with Hsp90; however, its function in RNAi remains elusive...
  19. Iwasaki S, Kobayashi M, Yoda M, Sakaguchi Y, Katsuma S, Suzuki T, et al. Hsc70/Hsp90 chaperone machinery mediates ATP-dependent RISC loading of small RNA duplexes. Mol Cell. 2010;39:292-9 pubmed publisher
    ..Here we show that the Hsc70/Hsp90 chaperone machinery is required to load small RNA duplexes into Argonaute proteins, but not for subsequent strand ..
  20. Fernandes M, Xiao H, Lis J. Binding of heat shock factor to and transcriptional activation of heat shock genes in Drosophila. Nucleic Acids Res. 1995;23:4799-804 pubmed
    ..This last result suggests that close proximity of HSEs for cooperative binding of HSF is a result of protein-protein interactions near the point of DNA contact. ..
  21. Milton C, Ulane C, Rutherford S. Control of canalization and evolvability by Hsp90. PLoS ONE. 2006;1:e75 pubmed
    Partial reduction of Hsp90 increases expression of morphological novelty in qualitative traits of Drosophila and Arabidopsis, but the extent to which the Hsp90 chaperone also controls smaller and more likely adaptive changes in natural ..
  22. Ashburner M. Patterns of puffing activity in the salivary gland chromosomes of Drosophila. V. Responses to environmental treatments. Chromosoma. 1970;31:356-76 pubmed
  23. Morrow G, Battistini S, Zhang P, Tanguay R. Decreased lifespan in the absence of expression of the mitochondrial small heat shock protein Hsp22 in Drosophila. J Biol Chem. 2004;279:43382-5 pubmed
    ..The absence of Hsp22 also sensitizes flies to mild stress. These data support a key role of sHsps in aging and underline the importance of mitochondrial sHsps in this process. ..
  24. Kampmueller K, Miller D. The cellular chaperone heat shock protein 90 facilitates Flock House virus RNA replication in Drosophila cells. J Virol. 2005;79:6827-37 pubmed
    ..We investigated the role of the cellular chaperone heat shock protein 90 (Hsp90) in viral RNA replication complex assembly and function using Flock House virus (FHV), an alphanodavirus whose RNA-..
  25. Bonner J, Kerby R. RNA polymerase II transcribes all of the heat shock induced genes of Drosophila melanogaster. Chromosoma. 1982;85:93-108 pubmed
    ..Thus the protein-coding and non-protein-coding heat shock-induced RNAs are transcribed by this polymerase specifically. We have also identified several non-puffed chromosomal sites at which RNA synthesis is induced by heat shock. ..
  26. Gangaraju V, Yin H, Weiner M, Wang J, Huang X, Lin H. Drosophila Piwi functions in Hsp90-mediated suppression of phenotypic variation. Nat Genet. 2011;43:153-8 pubmed publisher
    ..In Drosophila, Hsp90, the trithorax-group proteins and transposon silencing have been previously implicated in canalization...
  27. Song Y, Fee L, Lee T, Wharton R. The molecular chaperone Hsp90 is required for mRNA localization in Drosophila melanogaster embryos. Genetics. 2007;176:2213-22 pubmed
    ..Here we use genetic approaches to show that the Hsp90 chaperone (encoded by Hsp83 in Drosophila) is a localization factor for two mRNAs, nanos and pgc...
  28. Sangster T, Lindquist S, Queitsch C. Under cover: causes, effects and implications of Hsp90-mediated genetic capacitance. Bioessays. 2004;26:348-62 pubmed
    The environmentally responsive molecular chaperone Hsp90 assists the maturation of many key regulatory proteins...
  29. Wohlwill A, Bonner J. Genetic analysis of chromosome region 63 of Drosophila melanogaster. Genetics. 1991;128:763-75 pubmed
    ..analyzed in order to (1) characterize this previously unstudied region and (2) attempt to isolate mutations in the hsp82 gene. Seven deletions which span this region were isolated, including four which remove the hsp82 gene...
  30. Faucheux M, Roignant J, Netter S, Charollais J, Antoniewski C, Theodore L. batman Interacts with polycomb and trithorax group genes and encodes a BTB/POZ protein that is included in a complex containing GAGA factor. Mol Cell Biol. 2003;23:1181-95 pubmed
    ..Together, our results suggest that batman belongs to a subset of the Polycomb/trithorax group of genes that includes Trithorax-like, whose products are involved in both activation and repression of homeotic genes. ..
  31. Auluck P, Bonini N. Pharmacological prevention of Parkinson disease in Drosophila. Nat Med. 2002;8:1185-6 pubmed
  32. Morettini S, Tribus M, Zeilner A, Sebald J, Campo Fernandez B, Scheran G, et al. The chromodomains of CHD1 are critical for enzymatic activity but less important for chromatin localization. Nucleic Acids Res. 2011;39:3103-15 pubmed publisher
    ..Chromodomain mutations negatively affect the chromatin assembly activities of CHD1 in vitro, and they appear to be involved in linking the ATP-dependent motor to the chromatin assembly function of CHD1. ..
  33. Law A, Hirayoshi K, O BRIEN T, Lis J. Direct cloning of DNA that interacts in vivo with a specific protein: application to RNA polymerase II and sites of pausing in Drosophila. Nucleic Acids Res. 1998;26:919-24 pubmed
    ..At least some of these map to the 5'-ends of genes. These results suggest that transcriptional pausing of Pol II is a general phenomenon in vivo. ..
  34. Sgrò C, Milton C, Jensen L, Frydenberg J, Loeschcke V, Batterham P, et al. Nucleotide diversity in the Hsp90 gene in natural populations of Drosophila melanogaster from Australia. Insect Mol Biol. 2008;17:685-97 pubmed publisher
    b>Hsp90 is regarded as one of the best candidates for an evolved mechanism that regulates the expression of genetic and phenotypic variability...
  35. Chen B, Zhong D, Monteiro A. Comparative genomics and evolution of the HSP90 family of genes across all kingdoms of organisms. BMC Genomics. 2006;7:156 pubmed
    b>HSP90 proteins are essential molecular chaperones involved in signal transduction, cell cycle control, stress management, and folding, degradation, and transport of proteins...
  36. Smith S, Petruk S, Sedkov Y, Cho E, Tillib S, Canaani E, et al. Modulation of heat shock gene expression by the TAC1 chromatin-modifying complex. Nat Cell Biol. 2004;6:162-7 pubmed
    ..Consistently, TAC1 is required for methylation and acetylation of nucleosomal histones in the 5'-coding region of hsp70 after induction, suggesting an unexpected role for TAC1 during transcriptional elongation. ..
  37. Zimarino V, Tsai C, Wu C. Complex modes of heat shock factor activation. Mol Cell Biol. 1990;10:752-9 pubmed
    ..It appears that despite conservation of the HSE in evolution, the means by which HSF is activated to bind DNA in higher and lower eucaryotes may have diverged. ..
  38. Marchler G, Wu C. Modulation of Drosophila heat shock transcription factor activity by the molecular chaperone DROJ1. EMBO J. 2001;20:499-509 pubmed
    ..level, modest when DROJ1 was depleted alone, reached maximal levels when DROJ1 and HSP70/HSC70, or DROJ1 and HSP90, were depleted concurrently...
  39. Milton C, Batterham P, McKenzie J, Hoffmann A. Effect of E(sev) and Su(Raf) Hsp83 mutants and trans-heterozygotes on bristle trait means and variation in Drosophila melanogaster. Genetics. 2005;171:119-30 pubmed
    The Hsp90 protein encoded by the Hsp83 gene is required for the development of many traits in Drosophila...
  40. Cutforth T, Rubin G. Mutations in Hsp83 and cdc37 impair signaling by the sevenless receptor tyrosine kinase in Drosophila. Cell. 1994;77:1027-36 pubmed
    ..We show here that E(sev)3A is a member of the Hsp90 family of stress proteins and that E(sev)3B encodes a homolog of the cell cycle control protein Cdc37 from S...
  41. Specchia V, Piacentini L, Tritto P, Fanti L, D Alessandro R, Palumbo G, et al. Hsp90 prevents phenotypic variation by suppressing the mutagenic activity of transposons. Nature. 2010;463:662-5 pubmed publisher
    ..Recent studies on Hsp90, a protein involved in several cellular processes and development pathways, indicate that it is a possible ..
  42. Yue L, Karr T, Nathan D, Swift H, Srinivasan S, Lindquist S. Genetic analysis of viable Hsp90 alleles reveals a critical role in Drosophila spermatogenesis. Genetics. 1999;151:1065-79 pubmed
    ..We also report that scratch, a previously identified male-sterile mutation, is an allele of Hsp82 with a P-element insertion in the intron ..
  43. Singh M, Reddy M, Mathur N, Saxena D, Chowdhuri D. Induction of hsp70, hsp60, hsp83 and hsp26 and oxidative stress markers in benzene, toluene and xylene exposed Drosophila melanogaster: role of ROS generation. Toxicol Appl Pharmacol. 2009;235:226-43 pubmed publisher
    ..Third instar larvae of D. melanogaster transgenic for hsp70, hsp83 and hsp26 and Oregon R(+) strain were exposed to 1.0-100...
  44. Ding D, Parkhurst S, Halsell S, Lipshitz H. Dynamic Hsp83 RNA localization during Drosophila oogenesis and embryogenesis. Mol Cell Biol. 1993;13:3773-81 pubmed
    b>Hsp83 is the Drosophila homolog of the mammalian Hsp90 family of regulatory molecular chaperones...
  45. Shaw P, Franken P. Perchance to dream: solving the mystery of sleep through genetic analysis. J Neurobiol. 2003;54:179-202 pubmed
    ..In this article we will review recent studies that have used genetic techniques to evaluate sleep in the fruit fly and the mouse. ..
  46. Guertin M, Lis J. Chromatin landscape dictates HSF binding to target DNA elements. PLoS Genet. 2010;6:e1001114 pubmed publisher
  47. Pigliucci M. Developmental genetics: buffer zone. Nature. 2002;417:598-9 pubmed
  48. Carbajal M, Valet J, Charest P, Tanguay R. Purification of Drosophila hsp 83 and immunoelectron microscopic localization. Eur J Cell Biol. 1990;52:147-56 pubmed
    ..This intracellular distribution of hsp 83 is consistent with its reported association with various cellular proteins and suggest that this hsp may be involved in their intracellular transport and/or in the modulation of their activity. ..
  49. Yao J, Ardehali M, Fecko C, Webb W, Lis J. Intranuclear distribution and local dynamics of RNA polymerase II during transcription activation. Mol Cell. 2007;28:978-90 pubmed
    ..Pol II at highly transcribed developmental loci exhibits dynamics resembling combinations of these Hsp70 transcription modes. ..
  50. Crevel G, Bates H, Huikeshoven H, Cotterill S. The Drosophila Dpit47 protein is a nuclear Hsp90 co-chaperone that interacts with DNA polymerase alpha. J Cell Sci. 2001;114:2015-25 pubmed
    b>Hsp90 is gaining increasing importance as a protein involved in controlling the normal functioning of the cell...
  51. Dorsett D, Viglianti G, Rutledge B, Meselson M. Alteration of hsp82 gene expression by the gypsy transposon and suppressor genes in Drosophila melanogaster. Genes Dev. 1989;3:454-68 pubmed
    ..modifier genes were investigated by inserting gypsy or fragments of it into the intron of the Drosophila hsp82 heat shock gene...
  52. Fuda N, Buckley M, Wei W, Core L, Waters C, Reinberg D, et al. Fcp1 dephosphorylation of the RNA polymerase II C-terminal domain is required for efficient transcription of heat shock genes. Mol Cell Biol. 2012;32:3428-37 pubmed publisher
    ..result of a loss of Pol II in the coding region of highly transcribed heat shock-induced genes: Hsp70, Hsp26, and Hsp83. Moreover, Fcp1 depletion dramatically increases phosphorylation of the non-chromatin-bound Pol II...
  53. Andolfatto P, Depaulis F, Navarro A. Inversion polymorphisms and nucleotide variability in Drosophila. Genet Res. 2001;77:1-8 pubmed
  54. Kimura Y, Rutherford S, Miyata Y, Yahara I, Freeman B, Yue L, et al. Cdc37 is a molecular chaperone with specific functions in signal transduction. Genes Dev. 1997;11:1775-85 pubmed
    ..Strikingly, many pathways involving Cdc37 also involve the protein chaperone Hsp90. The identification of Cdc37 as the 50-kD protein in several Hsp90-kinase complexes, together with other data, led ..
  55. Costa A, Pazman C, Sinsimer K, Wong L, McLeod I, Yates J, et al. Rasputin functions as a positive regulator of orb in Drosophila oogenesis. PLoS ONE. 2013;8:e72864 pubmed publisher
    ..Tandem Mass Spectrometry analysis shows that several canonical stress granule proteins are associated with the Orb-Rin complex suggesting that a conserved mRNP complex regulates localized translation during oogenesis in Drosophila. ..
  56. Trindade de Paula M, Poetini Silva M, Machado Araujo S, Cardoso Bortolotto V, Barreto Meichtry L, Zemolin A, et al. High-Fat Diet Induces Oxidative Stress and MPK2 and HSP83 Gene Expression in Drosophila melanogaster. Oxid Med Cell Longev. 2016;2016:4018157 pubmed publisher
    ..lipid peroxidation and antioxidant enzymes SOD and CAT activity, and mRNA expression of antioxidant enzymes HSP83 and MPK2 were analyzed. To confirm the damage effect of diet on flies, survival and lifespan were investigated...
  57. de Renzis S, Elemento O, Tavazoie S, Wieschaus E. Unmasking activation of the zygotic genome using chromosomal deletions in the Drosophila embryo. PLoS Biol. 2007;5:e117 pubmed
    ..We propose that this regulatory mode links morphogen gradients with temporal regulation during the maternal-to-zygotic transition. ..
  58. Zatsepina O, Velikodvorskaia V, Molodtsov V, Garbuz D, Lerman D, Bettencourt B, et al. A Drosophila melanogaster strain from sub-equatorial Africa has exceptional thermotolerance but decreased Hsp70 expression. J Exp Biol. 2001;204:1869-81 pubmed
    ..We hypothesize that the reduced Hsp70 expression in a Drosophila melanogaster strain living chronically at intermediate temperatures may represent an evolved suppression of the deleterious phenotypes of Hsp70. ..
  59. Dickson B, van der Straten A, Dominguez M, Hafen E. Mutations Modulating Raf signaling in Drosophila eye development. Genetics. 1996;142:163-71 pubmed
    ..We present the results of this screen in detail, as well as a preliminary genetic analysis of the six loci still to be characterized molecularly. ..
  60. Wu C. Two protein-binding sites in chromatin implicated in the activation of heat-shock genes. Nature. 1984;309:229-34 pubmed
    ..The pattern of resistance before and after induction of gene expression suggests that heat-shock genes are activated by the sequential binding of at least two protein factors. ..
  61. Hackett R, Lis J. Localization of the hsp83 transcript within a 3292 nucleotide sequence from the 63B heat shock locus of D. melanogaster. Nucleic Acids Res. 1983;11:7011-30 pubmed
    ..start of transcription and RNA splice sites of the unique gene that encodes the 83,000 d heat shock polypeptide (hsp83 gene) by S1 mapping and synthesis of cDNA from restriction fragment primed mRNA...