Skip to main content

Microcell Fusion Technique – Detailed Notes


Microcell Fusion Technique – Detailed Notes


1. Definition 

Microcell fusion is a technique in which microcells containing isolated chromosomes or chromosomal fragments from a donor cell are fused with recipient cells.
It is used for chromosome transfer, gene mapping, and creating hybrid cell lines.
Also called microcell-mediated chromosome transfer (MMCT).
2. Principle
Donor cells containing the chromosome of interest are treated with colchicine to induce micronuclei formation.
These micronuclei are isolated as microcells (small cytoplasmic vesicles containing one or a few chromosomes).
Microcells are fused with recipient cells using fusion agents such as PEG or Sendai virus.
The chromosome from the donor is incorporated into the recipient cell, creating a stable hybrid.
Key Concept:
Microcell fusion allows transfer of specific chromosomes from donor to recipient without introducing the whole genome.


3. Steps in Microcell Fusion Technique


Step 1: Preparation of Donor Cells

Donor cells contain the chromosome(s) of interest, often labeled with selectable markers.
Cells are treated with colchicine, which disrupts mitotic spindle formation.
This produces micronuclei, small nuclear fragments containing single chromosomes.

Step 2: Isolation of Microcells

Micronucleated donor cells are treated with cytochalasin B, which inhibits cytoplasmic division.
Cells are centrifuged through a Percoll density gradient to isolate microcells.
Microcells are small vesicles (~2–5 µm) containing single or few chromosomes.

Step 3: Fusion with Recipient Cells


Microcells are fused with recipient cells using:
A. PEG-Mediated Fusion
Polyethylene glycol induces membrane fusion between microcells and recipient cells.
B. Virus-Mediated Fusion
Inactivated Sendai virus is used to facilitate fusion of microcell membranes with recipient cells.

Step 4: Selection of Hybrid Cells

Recipient cells receiving the donor chromosome are selected using selectable markers (e.g., antibiotic resistance, reporter genes).
Hybrid cells are then expanded in culture.

Step 5: Analysis of Hybrid Cells

Hybrid cells are analyzed for chromosome retention, gene expression, and functional traits.
Techniques include:
Karyotyping
Fluorescent in situ hybridization (FISH)
PCR or molecular markers

4. Factors Affecting Microcell Fusion

Donor cell preparation – Colchicine concentration and treatment duration
Recipient cell type – Must be compatible and capable of growth
Fusion method – PEG concentration, viral activity, incubation time
Selection strategy – Choice of selectable markers
Microcell viability – Critical for successful fusion
5. Applications of Microcell Fusion Technique

5.1 Gene Mapping


Transfer individual chromosomes to recipient cells for mapping gene loci.
Example: Transfer human chromosome 21 into hamster cells for mapping Down syndrome-related genes.

5.2 Functional Genomics

Study gene function by isolating and expressing single donor chromosomes in a new cellular environment.

5.3 Production of Hybrid Cell Lines

Generate somatic cell hybrids with specific chromosomes for research.
Example: Human-mouse hybrid cell lines for gene expression studies.

5.4 Disease Research


Study genetic diseases by transferring mutant chromosomes into recipient cells.
Example: Identify genes responsible for metabolic disorders.

5.5 Chromosome Engineering

Combine specific donor chromosomes with recipient cells for gene transfer and therapeutic research.

6. Advantages of Microcell Fusion


Transfer specific chromosomes or chromosomal fragments
Bypasses sexual or species barriers
Produces stable hybrid cell lines
Useful in gene mapping and functional genomics
Can introduce large DNA fragments that are difficult with plasmids or viral vectors

7. Limitations
Technically demanding and labor-intensive
Low efficiency of microcell fusion
Requires careful donor cell preparation
Hybrid cells may lose donor chromosomes over time
Requires selectable markers for identification

8. Examples
Donor Chromosome
Recipient Cell
Purpose
Human chromosome 21
Chinese hamster ovary (CHO) cells
Gene mapping, Down syndrome studies
Human chromosome 7
Mouse cells
Functional genomics, disease gene identification
Specific donor chromosome
Fibroblast cells
Production of hybrid cell lines for research

Advantages
Transfer specific chromosomes, bypass sexual barriers, stable hybrids.

Limitations
Technically demanding, low efficiency, requires selection



Microcell Fusion Technique – 50 MCQs


Microcell fusion is used to:
a) Fuse plant protoplasts
b) Transfer donor chromosomes to recipient cells ✅
c) Fuse viral particles
d) Introduce RNA only
Microcell fusion is also called:
a) Somatic hybridization
b) Microcell-mediated chromosome transfer (MMCT) ✅
c) DNA-mediated transformation
d) Lipofection
Microcells are:
a) Whole donor cells
b) Cytoplasmic vesicles containing one or few chromosomes ✅
c) Viral particles
d) Plasmids
Donor cells are treated with which chemical to induce micronuclei?
a) PEG
b) Colchicine ✅
c) Cytochalasin B
d) Cellulase
Cytochalasin B is used to:
a) Induce fusion
b) Prevent cytoplasmic division and isolate microcells ✅
c) Digest cell walls
d) Label chromosomes
Microcells contain:
a) Entire genome
b) One or few chromosomes ✅
c) Only RNA
d) Only cytoplasm
Fusion of microcells with recipient cells can be done by:
a) PEG-mediated fusion ✅
b) Electroporation
c) Lipofection
d) Calcium phosphate precipitation
Virus-mediated fusion uses:
a) Active viruses
b) Inactivated Sendai virus ✅
c) Retrovirus
d) Adenovirus
Microcell fusion is primarily applied in:
a) Plant protoplast fusion
b) Chromosome transfer and hybrid cell production ✅
c) Bacterial transformation
d) RNA interference
Selectable markers are important in microcell fusion to:
a) Induce fusion
b) Identify successful hybrid cells ✅
c) Digest cell walls
d) Label chromosomes
Hybrid cells generated by microcell fusion contain:
a) Only recipient chromosomes
b) Donor chromosome(s) plus recipient genome ✅
c) Only donor chromosomes
d) Only cytoplasm
Donor cell chromosomes may be labeled with:
a) Fluorescent markers ✅
b) PEG
c) Colchicine
d) Lipid vesicles
Density gradient centrifugation is used to:
a) Fuse microcells
b) Isolate microcells ✅
c) Select hybrid cells
d) Digest cell walls
PEG (Polyethylene Glycol) in microcell fusion acts by:
a) Digesting cell walls
b) Destabilizing membranes to allow fusion ✅
c) Selecting hybrid cells
d) Labeling chromosomes
Which of the following is a key advantage of microcell fusion?
a) Transfers only RNA
b) Transfers specific donor chromosomes ✅
c) Works without donor cell preparation
d) Requires no selection
Microcell fusion bypasses:
a) Sexual reproductive barriers ✅
b) Cell culture
c) DNA transfer
d) Protein synthesis
Donor cells must be treated with colchicine for:
a) 1–2 minutes
b) Several hours to induce micronuclei formation ✅
c) Only to label chromosomes
d) To digest the cytoplasm
Microcells are typically:
a) 20–50 µm
b) 2–5 µm ✅
c) 10–15 µm
d) 50–100 µm
Cytochalasin B inhibits:
a) DNA replication
b) Cytokinesis ✅
c) Chromosome segregation
d) Nuclear division
Hybrid cell lines created by microcell fusion are useful for:
a) Gene mapping ✅
b) Functional genomics ✅
c) Disease research ✅
d) All of the above ✅
Microcell fusion efficiency depends on:
a) Donor cell preparation ✅
b) Recipient cell type ✅
c) Fusion method and incubation conditions ✅
d) All of the above ✅
Hybrid cells can be analyzed using:
a) Karyotyping ✅
b) FISH (Fluorescent in situ hybridization) ✅
c) PCR ✅
d) All of the above ✅
Microcell fusion can transfer:
a) Nuclear chromosomes ✅
b) Cytoplasmic organelles
c) Only DNA plasmids
d) Only RNA
Donor chromosomes may carry:
a) Selectable markers ✅
b) Antibiotic resistance genes ✅
c) Reporter genes ✅
d) All of the above ✅
Microcell fusion is technically:
a) Simple and fast
b) Labor-intensive and demanding ✅
c) Only for plants
d) Only for bacteria
Hybrid cells are selected based on:
a) Morphology
b) Marker gene expression ✅
c) Chromosome number
d) Cell size
Microcell fusion can be applied to study:
a) Gene function ✅
b) Disease mechanisms ✅
c) Chromosome mapping ✅
d) All of the above ✅
Donor cells for microcell fusion are often:
a) Tumor cells ✅
b) Plant cells
c) Bacterial cells
d) Viral particles
Which step is critical for microcell viability?
a) Colchicine treatment duration ✅
b) Fusion method
c) Selectable marker choice
d) PCR analysis
Hybrid cells may lose donor chromosomes over time due to:
a) Culture instability ✅
b) Fusion method
c) PEG concentration
d) Colchicine treatment
Microcell fusion can transfer:
a) Single chromosomes ✅
b) Multiple chromosomes ✅
c) Entire genome
d) Both a & b ✅
Microcell fusion is used in human genetics to:
a) Study Down syndrome genes ✅
b) Study plant traits
c) Bacterial cloning
d) Viral replication
Hybrid cells can express genes from:
a) Donor chromosomes ✅
b) Recipient chromosomes ✅
c) Both donor and recipient ✅
d) None
A limitation of microcell fusion is:
a) High efficiency
b) Requires careful donor cell preparation ✅
c) Works without selection
d) Can transfer RNA only
Sendai virus in microcell fusion functions as:
a) Selectable marker
b) Fusion agent ✅
c) Donor chromosome carrier
d) Cytoplasmic stabilizer
Hybrid cells are maintained in culture using:
a) Selective medium ✅
b) PEG only
c) Colchicine only
d) Viral infection
Applications of microcell fusion in cancer research include:
a) Mapping oncogenes ✅
b) Generating hybrid cell lines ✅
c) Functional genomics ✅
d) All of the above ✅
Microcell fusion can transfer which types of chromosomes?
a) Autosomes ✅
b) Sex chromosomes ✅
c) Fragmented chromosomes ✅
d) All of the above ✅
Hybrid cells can be used to study:
a) Drug resistance ✅
b) Gene expression ✅
c) Cytogenetic abnormalities ✅
d) All of the above ✅
Microcell fusion differs from protoplast fusion because:
a) It transfers whole cells
b) It transfers only chromosomes, not whole cells ✅
c) It uses plant tissues only
d) It uses viral vectors
Key chemical for micronuclei induction is:
a) PEG
b) Colchicine ✅
c) Cytochalasin B
d) Calcium chloride
PEG is used in microcell fusion to:
a) Digest cell walls
b) Promote membrane fusion ✅
c) Select hybrid cells
d) Label chromosomes
Donor chromosomes may be marked with:
a) Fluorescent probes ✅
b) Antibiotic resistance genes ✅
c) Reporter genes ✅
d) All of the above ✅
Density gradient centrifugation isolates:
a) Donor chromosomes
b) Microcells ✅
c) Recipient nuclei
d) Viral particles
Microcell fusion can produce stable hybrids for:
a) Long-term gene mapping ✅
b) Temporary expression
c) Only protoplast studies
d) Only viral vectors
Hybrid cells can retain donor chromosomes depending on:
a) Culture conditions ✅
b) Donor chromosome type ✅
c) Selective pressure ✅
d) All of the above ✅
Microcell fusion is used in mapping which human chromosome associated with Down syndrome?
a) Chromosome 21 ✅
b) Chromosome 7
c) Chromosome 1
d) Chromosome X
Hybrid cells from microcell fusion are analyzed by:
a) Karyotyping ✅
b) PCR ✅
c) FISH ✅
d) All of the above ✅
A major advantage of microcell fusion is:
a) Transfers whole donor genome
b) Transfers specific chromosomes ✅
c) No selection required
d) Works only in plants
Overall, microcell fusion is important in:
a) Gene mapping ✅
b) Functional genomics ✅
c) Disease research ✅
d) All of the above ✅


Comments

Post a Comment

Popular Posts

••CLASSIFICATION OF ALGAE - FRITSCH

      MODULE -1       PHYCOLOGY  CLASSIFICATION OF ALGAE - FRITSCH  ❖F.E. Fritsch (1935, 1945) in his book“The Structure and  Reproduction of the Algae”proposed a system of classification of  algae. He treated algae giving rank of division and divided it into 11  classes. His classification of algae is mainly based upon characters of  pigments, flagella and reserve food material.     Classification of Fritsch was based on the following criteria o Pigmentation. o Types of flagella  o Assimilatory products  o Thallus structure  o Method of reproduction          Fritsch divided algae into the following 11 classes  1. Chlorophyceae  2. Xanthophyceae  3. Chrysophyceae  4. Bacillariophyceae  5. Cryptophyceae  6. Dinophyceae  7. Chloromonadineae  8. Euglenineae    9. Phaeophyceae  10. Rhodophyceae  11. Myxophyce...
Post a Comment
Read more

ANTIGEN

1. Definition of ANTIGEN An antigen is any substance which, when introduced into the body, induces an immune response and specifically reacts with antibodies or sensitized T-cells. 👉 Substances may be foreign or self, but immunogenic antigens are usually foreign molecules. 2. Immunogen vs Antigen Immunogen Substance that induces immune response Antigen Substance that reacts with immune products Hapten Antigenic but not immunogenic alone 👉 All immunogens are antigens, but all antigens are not immunogens. 3. Chemical Nature of Antigens Antigens may be: a) Proteins (Most potent) Enzymes Toxins Structural proteins b) Polysaccharides Bacterial capsules Cell wall components c) Glycoproteins Viral envelope proteins d) Lipids & Nucleic acids Weakly antigenic Become immunogenic when combined with proteins 4. Properties of Antigens An ideal antigen shows: Foreignness High molecular weight (>10,000 Da) Chemical complexity Stability Specificity Degradability (processing by APCs) 5. Types ...
Post a Comment
Read more

MHC MOLECULES NOTES AND MCQ

MHC MOLECULES  1. INTRODUCTION MHC (Major Histocompatibility Complex): A set of cell surface proteins essential for the adaptive immune system to recognize foreign molecules. Function: Presents antigenic peptides to T cells, initiating immune responses. Location: Found in all vertebrates; in humans, MHC is called HLA (Human Leukocyte Antigen). HLA Full Form: Human Leukocyte Antigen 2. Types of MHC Molecules MHC molecules are classified into two main classes and a third minor class: A. Class I MHC (MHC-I) Expression: On all nucleated cells (except RBCs) Function: Presents endogenous antigens (from inside the cell, e.g., viral proteins) to CD8+ cytotoxic T cells Structure: Heavy α chain (3 domains: α1, α2, α3) Light chain (β2-microglobulin) Peptide-binding groove formed by α1 and α2 Peptide length: Typically 8–10 amino acids Genes: HLA-A, HLA-B, HLA-C (highly polymorphic) B. Class II MHC (MHC-II) Expression: On antigen-presenting cells (APCs) like dendritic cells, macrophages, B cell...
Post a Comment
Read more

Southern Blotting

Southern Blotting  Introduction Southern blotting is a molecular biology technique used for the detection of specific DNA sequences in a complex mixture of DNA. It was developed by Edwin M. Southern in 1975. The method involves restriction digestion of DNA, separation by gel electrophoresis, transfer (blotting) onto a membrane, and hybridization with a labeled DNA probe. Principle of Southern Blotting The technique is based on the principle of complementary base pairing. A single-stranded labeled DNA probe hybridizes specifically with its complementary DNA sequence immobilized on a membrane. Detection of the label confirms the presence and size of the target DNA fragment. Steps Involved in Southern Blotting. 1. Isolation of DNA Genomic DNA is extracted from cells or tissues. DNA must be pure and intact to ensure accurate results. 2. Restriction Enzyme  Digestion DNA is digested using specific restriction endonucleases. Produces DNA fragments of varying lengths. Choice of enzym...
Post a Comment
Read more

Third Semester M.Sc. Degree Examination, December 2025BotanyBO 531: PLANT BREEDING, HORTICULTURE AND BIOSTATISTICS.

Third Semester M.Sc. Degree Examination, December 2025 Botany BO 531: PLANT BREEDING, HORTICULTURE AND BIOSTATISTICS (2024 Admission) Time: 3 Hours Max. Marks: 75 Answer these questions in one or two sentences.  Each question carries 1 mark. 1. Who introduced maize in India? 2.Name an organization in India for plant introduction. 3.  What is BSI? 4.What is Super Rice? 5.Define somaticplastic sterility? 6.What is a chemical mutagen? Give example. 7.What is Arboriculture? 8.What is MAP in Horticulture? 9.Define probability. 10. What is LSD in Biostatistics? (10 × 1 = 10 Marks) II.Answer the following questions in not more than 50 words . 11] Comment on Primary plant introduction.                OR 12. What are microcenters? Explain. 13.Explain zygotic sterility. How can we overcome this in plant breeding?                          OR 14 Describe a green house and its uses. ...
Post a Comment
Read more

Mapping of DNA

DNA MAPPING   1. Introduction DNA mapping refers to the process of determining the relative positions of genes or DNA sequences on a chromosome. It provides information about the organization, structure, and distance between genetic markers in a genome. DNA mapping is an essential step toward genome sequencing, gene identification, disease diagnosis, and genetic engineering. DNA maps serve as roadmaps that guide researchers to locate specific genes associated with traits or diseases. 2. Objectives of DNA Mapping To locate genes on chromosomes To determine the order of genes To estimate distances between genes or markers To study genome organization To assist in genome sequencing projects. 3. Principles of DNA Mapping DNA mapping is based on: Recombination frequency Physical distance between DNA fragments Hybridization of complementary DNA Restriction enzyme digestion Use of genetic markers The closer two genes are, the less frequently they recombine during meiosis. 4 . Types of DNA...
2 comments
Read more

Plaque Blotting Technique

Plaque Blotting Technique Introduction Plaque blotting is a molecular biology screening technique used to identify specific DNA or RNA sequences present in bacteriophage plaques formed on a bacterial lawn. It is especially useful in the screening of recombinant phage libraries such as λ (lambda) phage genomic or cDNA libraries. This technique combines: Plaque assay (to isolate individual phage clones) Blotting technique (to transfer nucleic acids onto a membrane) Hybridization (to detect specific sequences using labeled probes) Principle of Plaque Blotting The principle of plaque blotting is based on nucleic acid hybridization. Each plaque represents a clone of phage particles containing identical DNA. DNA from phage particles in plaques is: Released Denatured into single strands Transferred onto a nitrocellulose or nylon membrane The membrane is incubated with a labeled DNA/RNA probe complementary to the target sequence. Hybridization between probe and target DNA identifies positive p...
Post a Comment
Read more

PLANT INTROUCTION: TYPES AND PROCEDURE

PLANT INTROUCTION: TYPES AND PROCEDURE 1. Introduction Plant introduction is the transfer of plant species, varieties, or genotypes from one geographical area to another where they were not previously grown.  It is one of the oldest and most important methods of crop improvement and forms the basis of modern agriculture. Many important crops such as wheat, rice, maize, potato, cotton, sugarcane, and tobacco have been introduced from other countries. Definition : Plant introduction is the process of introducing plants or plant genetic material from their native or foreign regions into a new area for cultivation, evaluation, and utilization. 2. Objectives of Plant Introduction To increase crop productivity To introduce high-yielding varieties To obtain disease- and pest-resistant plants To introduce early maturing or drought-tolerant varieties To improve quality traits (oil content, protein, fiber, taste) To broaden the genetic base of crops To replace inferior local varieties To dev...
Post a Comment
Read more