86. The somatic cell hybridization of human and mouse cell can be effectively mediated by
(1) CaCl2 treatment
(2) Heat Shock
(3) Inactivated Sendai virus
(4) Enzymatic treatment
Somatic cell hybridization between human and mouse cells fuses non-reproductive cells to create hybrids useful for gene mapping and studying chromosome retention. This technique mixes cells from different species, often selecting for specific genetic markers post-fusion. The process requires agents that destabilize cell membranes to enable fusion without lysing the cells.
Option Analysis
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(1) CaCl2 treatment: Calcium chloride induces DNA uptake in bacterial transformation by altering membrane permeability but does not effectively fuse mammalian somatic cells like human and mouse. It stabilizes charge in some protocols but lacks the fusogenic power for interspecies hybridization.
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(2) Heat shock: Brief high-temperature exposure promotes DNA entry in prokaryotes or protein refolding but fails to mediate stable membrane fusion in eukaryotic somatic cell hybridization. It may damage cells without yielding viable hybrids.
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(3) Inactivated Sendai virus: This paramyxovirus, also called HVJ, binds sialic acid receptors on cells, promoting hemagglutination and fusion via its F and HN glycoproteins even when inactivated (UV or beta-propiolactone treated). It effectively creates human-mouse hybrids by facilitating membrane merging, as shown in early mapping studies.
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(4) Enzymatic treatment: Enzymes like cellulase or pectinase isolate protoplasts in plants by digesting cell walls but do not fuse animal somatic cells, which lack walls. They aid preparation but not hybridization itself.
Correct Answer and Explanation
The correct option is (3) Inactivated Sendai virus. This method mixes human and mouse cells with UV-inactivated virus, which triggers fusion efficiently while avoiding infection. Hybrids are selected using complementary mutants (e.g., mouse TK- with human HGPRT- cells in HAT medium), retaining specific human chromosomes for analysis. Other options like PEG or electrofusion exist but Sendai remains classic for human-rodent hybrids.
