title: Isolated total RNA and protein are preserved after thawing for more than twenty-four hours.
abstract: OBJECTIVE
  The preservation of biological samples at a low temperature is important for later biochemical and/or histological analyses. However, the molecular viability of thawed samples has not been studied sufficiently in depth. The present study was undertaken to evaluate the viability of intact tissues, tissue homogenates, and isolated total RNA after defrosting for more than twenty-four hours.
  
  
  METHODS
  The molecular viability of the thawed samples (n = 82) was assessed using the A260/A280 ratio, the RNA concentration, the RNA integrity, the level of intact mRNA determined by reverse transcriptase polymerase chain reaction, the protein level determined by Western blotting, and an examination of the histological structure.
  
  
  RESULTS
  The integrity of the total RNA was not preserved in the thawed intact tissue, but the RNA integrity and level of mRNA were perfectly preserved in isolated defrosted samples of total RNA. Additionally, the level of β-actin protein was preserved in both thawed intact tissue and homogenates.
  
  
  CONCLUSIONS
  Isolated total RNA does not undergo degradation due to thawing for at least 24 hours, and it is recommended to isolate the total RNA as soon as possible after tissue collection. Moreover, the protein level is preserved in defrosted tissues.
authors.affiliation: Laboratory of Experimental Hypertension, Department of Internal Medicine, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Ivone Braga de
authors.initials: IB
authors.lastname: Oliveira
authors.forename: Débora Rothstein
authors.initials: DR
authors.lastname: Ramos
authors.forename: Karen Lucasechi
authors.initials: KL
authors.lastname: Lopes
authors.forename: Regiane Machado de
authors.initials: RM
authors.lastname: Souza
authors.forename: Joel Claudio
authors.initials: JC
authors.lastname: Heimann
authors.forename: Luzia Naôko Shinohara
authors.initials: LN
authors.lastname: Furukawa
mesh_terms: D000199:Actins / Q000032:analysis; D000818:Animals; D015925:Cryopreservation / Q000379:methods*; D020869:Gene Expression Profiling / Q000379:methods*; D008297:Male; D023421:Models, Animal; D012313:RNA / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D020871:RNA Stability / Q000235:genetics* / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D013048:Specimen Handling / Q000379:methods*; D013997:Time Factors
chemical_list: D000199:Actins; D012313:RNA