Staining of Nucleic Acid by Acetocarmine

Objective  

Staining of nucleic acid by acetocarmine. 

 

Theory 

Staining nucleic acids with acetocarmine is a common laboratory method to visualize nucleic acids, specifically DNA and RNA. Acetocarmine is a stain composed of acetic acid and carmine, which binds with nucleic acids in the cells and tissues to facilitate better visualization under the microscope.  

What is nucleic Acid? 

  • Nucleic acids are complex organic macromolecules that are crucial in storing, transmitting, and expressing genetic information in all living organisms including viruses. 
  • Nucleic acids are naturally occurring chemical compounds that are the primary information-carrying molecules in living cells and make up the genetic material.  
  • There are two types of nucleic acids within cells, namely DNA and RNA, and both are long-chained polymers of nucleotides. 

DNA (deoxyribonucleic Acid) 

  • It is a long molecule of double-stranded deoxyribonucleic acid tightly bonded within the nucleus of eukaryotic cells and the cytoplasm of prokaryotic cells.  
  • It carries a heredity material encodes the genetic information’s that is essential for growth, development, functioning, and reproduction, etc.  
  • It comprises nucleotide units arranged in a double helix structure, formed by a sugar-phosphate backbone and nitrogenous bases (adenine, thymine, cytosine, guanine) that bonded in complementary pairs across the two strands.  

RNA (ribonucleic acid) 

  • It is a single-stranded molecule that mainly functions as the transmitter of genetic information and is essential in the cellular process of gene regulation and protein synthesis.  
  • Structurally, it consists of a ribose sugar backbone, phosphate groups, and four nitrogenous bases: adenine, cytosine, guanine, and uracil.   
  • It is produced from DNA during the transcription process and exists in different forms, such as messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) and each type serves various functions in the process of protein synthesis.  

Types of RNA 

Functions 

messenger RNA (mRNA) 

Carrying genetic information from DNA to ribosomes

transfer RNA (tRNA) 

Transferring amino acids during protein synthesis

ribosomal RNA (rRNA) 

Help in protein synthesis by assembling the amino acids 

 

                                         

                                                                                                                  Fig.1 Structure of DNA and RNA  

 

Acetocarmine stain 

  • It is a non–specific nuclear stain that binds with chromosomes and combines with nucleic acids to give out the formation of deep red – conjugate appearance to the nucleus.  
  • Mainly used to known about the different stages of mitosis in plant tissues.  
  • Also, it is used to study the process of cell multiplication. 
  • It is a simple and rapid staining technique used to visualize the cells without fixation.  
  • It is a non-specific stain, so it can be used to stain a variety of nuclear structures. 
  • It is an easy-to-use stain for cytology and histology. 

Preparation  

  • Acetocarmine stains are prepared by mixing saturated carmine with 45% glacial acetic acid.  
  • Carmine is a basic dye obtained from the offspring insect. 

Precaution 

  • The bottle kept in dark and stored at low temperature.  
  • Avoid inhalation or ingestion as this stain is harmful to health.  

 

Other stains and techniques involve in plant pathological studies 

  1. Ethidium Bromide - a well-known dye used for visualizing DNA in gel electrophoresis.  
  2. Giemsa staining - selectively binds to the phosphate groups of DNA molecules, allowing the chromosomes to be visible under a microscope. 
  3. Eva Green (green, fluorescent dye) – used in the detection of DNA quantitatively in Real time Polymerase Chain Reaction (RT-PCR) 
  4. Safranin and Fast Green Staining – both stains used to visualize cell wall components and plant tissues.  
  5. Iodine Staining – used to visualize the presence of starch in plant cells. 
  6. Alcian Blue Staining – used to visualize polysaccharides in plant tissues. 

 

Learning outcomes 

Students learn and understand:  

  • What are nuclei acids and type of nucleic acids.  
  • The functions of nucleic acids. 
  • The action of the stain acetocarmine with nucleic acids. and preparation and storage.