Glossary of Terms

Alignment
See also Dielectrophoresis and Pearl Chain. A consequence of cells being exposed to an inhomogeneous or divergent electric field, resulting in their movement toward the electrodes, and subsequent alignment or pearl chain formation.

Alternating Current (AC)
During electro cell fusion, an electrical current of alternating polarity is utilized to induce an non homogeneous, or divergent electric field, allowing for dielectrophoresis and pearl chain formation. The resulting physical contact between cells facilitates the fusion process that may result following the application of a DC electroporation pulse.

Capacitance
The ability of a body to store an electrical charge. Any object that can be electrically charged exhibits capacitance.

Capacitor
A device that stores energy in the form of an electric field. A capacitor consists of two metal plates insulated from each other by a dielectric (insulating, usually a plastic material such as Mylar) material. In an ideal capacitor, no conduction current flows between the plates after the capacitor is completely charged. Capacitors can be fixed, variable, or adjustable.

Cell Form
The format in which cells present for experimentation. Cell forms include suspension, in vivo, in ovo, ex plant, adherent, whole organism, etc.

Chambers
Electroporation and Electrofusion Chambers are the devices used to contain the cells/molecules to be fused/transfected. The chambers include the electrodes through which the pulse generators deliver the electric field to the cells. These include cuvettes as well as various fusion chambers and specialty electrodes.

Cloning
In terms of applications for electro cell fusion, cloning refers to the ability to generate identical, viable animals, through processes such as nuclear transplantation.

Compression
See Alignment, Dielectrophoresis, and Pearl Chains. The result of an AC alignment whereby the surfaces of cells in pearl chains are brought into close contact.

Dielectric Breakdown
The reversible breakdown of bi-lipid layer membranes as a result of the application of a DC electroporation pulse. A sufficiently high field strength may increase the membrane potential past a critical point leading to the breakdown of the membrane.

Dielectric Constant
For a given dielectric (nonmetallic) material, the ratio of electrical capacitance of a dielectric- filled capacitor to a vacuum capacitor of identical dimensions.

Dielectrophoresis
See Alignment. Dielectrophoresis is a phenomenon in which force is exerted on an object when it is subjected to a non-uniform electrical field. For the application of electrofusion, cells align into pearl chains through dielectrophoresis.

Dimer Formation
The bringing together of 2 cells, through the process of dielectrophoresis, so that they may be fused, resulting in a hybrid. Also refers to Pearl Chain formation.

Dielectric Breakdown
The reversible breakdown of bi-lipid layer membranes as a result of the application of a DC electroporation pulse. A sufficiently high field strength may increase the membrane potential past a critical point leading to the breakdown of the membrane.

Dielectric Constant
For a given dielectric (nonmetallic) material, the ratio of electrical capacitance of a dielectric-filled capacitor to a vacuum capacitor of identical dimensions.

Direct Current (DC)
During electro cell fusion, a direct current is utilized to produce a high intensity, short duration electric field of a single polarity, causing a reversible physical breakdown of bi-lipid membranes and resulting in the formation of temporary pores. When juxtaposed pores in the membranes of two or more cells reseal following the DC pulse, cells may become fused. During electroporation, a direct current is used to cause dielectric breakdown of the cell membrane to allow transfectant to enter.

Divergence
The deviation of field lines (e.g. electric field lines) from parallel, homogeneous conditions. A highly divergent field is a very inhomogeneous field where the value and direction of the field change drastically in the area under consideration.

Electric Field
The potential difference between two points (electrodes) (in Volts) divided by the distance between the electrodes (called gap, and expressed in cm). Expressed as V/cm or kV/cm. This is true only if the electric field is homogenous as it is in parallel plate electrodes.

Electric Field Force
The force acting on any charge in an electric field. The force is equal to the product of the charge and the electric field.

Electric Field Strength
See Electric Field. The strength of a homogenous Electric Field is expressed as V/cm or kV/cm.

Electrofusion (EF) or Electro Cell Fusion (ECF)
Electric field induced cell fusion. A novel physical means to bond two cells together by the application of an electric field pulse of high intensity.

Electrolytic
A fluid containing charged molecules is called an electrolyte. Electrolytic properties are associated with such a fluid, such as the ability to conduct current.

Electroporation
The application of high electric field pulses of short duration to create temporary pores (holes) in the membranes of cells.

Electroporation Cuvette
Square chambers with electrodes on two sides, usually measuring 1 mm, 2 mm or 4 mm in gap, for the purpose of electroporating cells in suspension. The cell type being electroporated typically determine the gap. Prokaryotic cells typically uses 1 mm or 2 mm gap cuvettes, while eukaryotic cells will typically use 2 mm or 4 mm gap sizes.

Embryo Manipulation
The cloning of animals can be accomplished through embryo manipulation techniques, such as nuclear transfer and electrofusion.

Exponential Decay Waveform
This waveform is mainly used for transforming cells during electroporation. In this type of pulse the set voltage is released from the capacitor and decays rapidly and exponentially over time (millisecs). The delivered pulse, is characterized by two parameters: the field strength (kV/cm) and the time constant. These parameters can be adjusted by varying voltage and capacitance settings to achieve a wide pulse gradient.

Field Strength
The potential difference between two points (electrodes) (in Volts) divided by the distance between the electrodes (called gap, and expressed in cm). Expressed as V/cm or kV/cm. This is true only if the electric field is homogeneous as it is in parallel plate electrodes. Gap – The distance between electrodes.

Frequency
The number of times an oscillation goes through a complete cycle in one second. Unit is Hertz (1/sec).

Homogenous Electric Field
The direction and field strength of a homogenous electrical field are constant.

Hybrid
A viable daughter cell resulting from the fusion of two parent cells.

Hybridoma
The fusion of an antibody producing cell with an immortalized cell, resulting in an immortalized hybrid cell capable of generating antibodies.

Hydrostatic Pressure
The pressure in liquids at rest.

Inhomogeneous Electric Field
Also see Divergence. Direction and strength of the electric field vary in an inhomogenous electric field.

Microslide
An electrofusion chamber allowing for the observation of the alignment and fusion processes under a microscope.

Number of Pulses
The number of electrical pulses the sample will be exposed to.

Osmotic Pressure
The applied pressure required to prevent the flow of solvents of different concentration across a semi-permeable membrane.

Pearl Chains
See Alignment and Dielectrophoresis. Chains of cells or vesicles brought into alignment during electro-cell fusion, prior to electroporation.

Pore
A small, mostly transient opening in a cell wall caused by the application of a brief high electric field pulse.

Potential Difference
The difference (in Volts) between points in an area between electrodes.

Pressure Gradient
The difference in pressure between two points in a medium.

Protocol
The method for performing an experiment.

Pulse Interval
The period of time between multiple electrical pulses.

Pulse Length/ Pulse Duration
The length of time an electric signal is applied.

Relaxation Time
The time of a system to reach equilibrium.

Rounding Off
The pheonomena of cells forming a sphere after being fused together.

Specialty Electrodes
Electrodes used with the BTX instruments to perform electroporation on a wide variety of cell forms. Some applications include in vivo, in ovo, in utero, or ex plant electroporation. BTX offer many types of specialty electrodes..

Square Waveform
This waveform is typically used for eukaryotic cells. During a square waveform pulse the voltage immediately jumps to the peak voltage and is held constant for the duration of the pulse, then immediately drops back to zero immediately at the end of the pulse. Square wave pulses are characterized by the voltage delivered, the duration of the pulse, the number of pulses, and the length of the interval time between pulses.

Time Constant
Represented by the Greek letter tau, T, is the amount of time required for the actual voltage of the delivered pulse to decrease to a value 1/e of the true peak pulse.

Transfectant
The cargo (for example, DNA, RNA, proteins, small molecules, or nanoparticles) that is being delivered into cells or tissues during electroporation.

Transfection
The introduction of molecules of interest into animal cells. Stable transfections result in integration of nucleic acids into host chromosomes and the inheritance of associated traits in progeny cells. Transient transfections result in temporary expression of exogenous nucleic acids.

Transformation
The introduction of nucleic acids into microorganisms and plant cells.

Turgor Pressure
The pressure in capillaries.

Voltage
The difference of electric potential between two electrodes. Voltage is expressed in volts (V) or kilovolts (kV).

Wave Forms
The shape of time-varying electric signals.