Posts Tagged ‘Laminar Air Flow’

Laminar Air Flow and Plant Tissue Culture

May 17th, 2014

Tissue culture is a biological method of asexual propagation where a very small piece of tissue (shoot apex, leaf section, or even an individual cell) is excised (which is known as Explants) and placed in sterile /aseptic culture in a test tube/petri dish/tissue culture container containing a special culture media.

A tissue culture is used for rapid multiplication of an organism. A very specialized laboratory with sterile/aseptic conditions is required for tissue culture. All the procedure involved in tissue culture should be carried out in a special ventilated cabinet and these conditions are provided by Laminar Air Flow.

The culture medium is a proper mixture of the nutrients (organic and inorganic), vitamins, sugars, minerals and plant hormones especially Cytokinin and Auxin for shoot and root initiation.

Steps involved in Tissue Culture are

  • Explants ; excision of the plant parts.
  • Place the explants in a tissue culture container/test tubes/petri dishes.
  • Multiplication ; Tissue grows and produce small plants.
  • Rapid multiplication by transfer of fresh culture.
  • Transplanting the plant into some kind of acclimation container.

Laminar Air Flow provides a work area with aseptic/sterile conditions for the tissue culture. Laminar Air Flow has continuous displacement of air (it provides streamline flow of air) that passes through HEPA (High Efficiency Particulate Air) filter that removes the particulates from the air.

Laminar Air Flow are equipped with a UV lamp that should be turned on about 10-20 minutes before being used to sterilize the shell or cabinet or the surface of the Laminar Air Flow to avoid any kind of contaminations. Wipe down the surface with ethanol before and after each use.

Laminar Air Flow can be vertical and horizontal. In the Vertical Laminar Air Flow the air blows down from the top of the cabinet. Vertical Laminar Air Flow is best for working with hazardous specimens since the aerosols that are generated in the cabinet are filtered out before they are released into the surrounding environments.

Horizontal Laminar Air Flow are designed such that the air flows directly at the operator hence they are not useful for working with hazardous specimens but are best protection for Tissue/cell culture.

Laminar Air Flow provides aseptic/sterile conditions for the preparation of Culture Media. All the culture vessels, test tubes, pipette, tip boxes, stocks of sterile eppendorfs should be opened only in the Laminar Air Flow to avoid any kind of contaminations. Culture Media cannot be prepared outside the Laminar Air Flow because it can get contaminated and there would not be any result.

What is Laminar Hood/Laminar Air Flow?

May 17th, 2014

Laminar Hood sometimes also known as Laminar Air Flow is an enclosed bench designed to prevent contaminations like biological particles (SPM) or any particle sensitive device. This closed cabinet is usually made up of stainless steel without any gap or joints where spores might collect.

Air is drawn through a High Efficiency Particulate Air (HEPA) filter and blown in a very smooth flow or streamline flow (when a fluid flows in a parallel layer with no disruption between the layers)

Laminar Hoods are equipped with a shortwave ultraviolet germicidal lamp to sterilize the shell or cabinet or the surface of the Hood. The Hoods should be turned on about 10-20monutes before being used to kill the germs. It is important to switch off this light during use as it may cause mutations and may give any exposed skin sunburn and may cause cataracts too. It is required to wipe down the cabinet surface with ethanol before and after use and it’s also required to keep the hood free of clutter as possible because this will interfere with the laminar flow air pattern.

Components of the Laminar Hood are

  • A Blower
  • High Efficiency performance Air filter
  • A Plenum Chamber (Pressurized housing containing air at positive pressure)

Why you need Laminar Hood?

  • It provides clean air to the working area.
  • It provides a constant flow of air out of the work area to prevent room air from entering.
  • The air that flows out from the Hood, removes contaminants introduced into the work area by personnel.

The most important  part of a laminar flow hood  is a High Efficiency Particulate Air filter (HEPA). Room air is taken into the unit and passed through a pre-filter to remove gross contaminants (lint, dust etc). The air is then compressed and channeled up behind and through the HEPA filter in a laminar flow fashion. The HEPA filter removes nearly all of the bacteria from the air.

What Safety Precautions should be taken for the Laminar Hood?

  • Large objects should never be placed near the back of the hood. These objects contaminate everything downstream and disrupt the laminar flow pattern of air too, which normally suspends the contaminants and removes them from the area.
  • Waste and other items should never enter the hood. All calculations should be done before entering the hood. And clutter should be less.
  • Hands should be cleaned by ethanol.Do not touch your hair, face or clothing while working.
  • Excess dust should be removed from items before introducing them into the hood.

Genetic Transformation and Laminar Air Flow

April 14th, 2014

Genetic transformation literally means change caused by genes, and involves the insertion of a gene (donor) into an organism (from recipient) in order to change the organism’s trait.

The process of transformation has certain common features:

  • The purified donor DNA is first transported across the cell membrane into the recipient “competent cells” (cells, that can take up DNA), and
  • The DNA then undergoes recombi­nation with the recipient DNA and is then expressed.

Genetic transformation is used in many areas of biotechnology.

  • In agriculture, genes coding for traits such as frost, pest, or spoilage resistance can be genetically transformed into plants.
  • In bioremediation, bacteria can be genetically transformed with genes enabling them to digest oil spills.
  • In medicine, diseases caused by defective genes are beginning to be treated by Gene Therapy; that is, by genetically transforming a sick person’s cells with healthy copies of the defective gene that causes the disease.

The main purpose of the Bacterial Transformation is to introduce a foreign plasmid into a bacterium and to use this bacterium to amplify the plasmid in order to make large quantities of this.

Bacteria can acquire new genetic information by three means:

  • Conjugation,
  • Transduction and
  • Transformation

During Conjugation, DNA is transferred directly from one organism to another, whereas in Transduction, the DNA is carried by Bacteriophages. And the Transformation includes insertion of naked DNA into bacterial cell with the help of different methods such as Electroporation and CaCl2 method etc.

But this Bacterial Transformation protocol should be done under aseptic environment so that no other bacterial genome can interfere with the genome of interest.

Maintenance of aseptic environment:

All culture vessels, media and instruments used in protocol must be sterilized. The importance is to keep the air surface and floor free of suspended particles and any other microorganisms. All operations are carried out in Laminar Air Flow, a sterile cabinet. Infection can be from

  • The air contains a large quantity of suspended microorganisms in the form of fungal and Bacterial spores.
  • The human body (a skin, breathe etc) carries several microorganisms.

Laminar Air Flow provides a work area with aseptic/sterile conditions. Laminar Air Flow has continuous displacement of air (it provides streamline flow of air) that passes through HEPA (High Efficiency Particulate Air) filter that removes the particulates from the air.

Laminar Air Flow are equipped with a UV lamp that should be turned on about 10-20 minutes  before being used to sterilize the shell or cabinet or the surface of the Laminar Air Flow to avoid any kind of contaminations. Wipe down the surface with ethanol before and after each use.