314 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animals 
STATE OF THE ART 
Combination of ova has led to early development 
to the blastocyst stage in the mouse but no further 
development following transfer has been reported. 
Initial success in experimentation with manipulation 
of pronuclei has been reported. 
FUTURE 
Cell fusion technology may someday prove useful 
for getting genetic material from a somatic cell into a 
fertilized 1-cell embryo for the purpose of cloning. In 
conjunction with tissue culture technology the tech- 
nology would have a role in gene mapping of chro- 
mosomes for the cow and perhaps other species. 
Combining ova of the same animal, "selfing,” 
would rapidly result in pure genetic (inbred) lines for 
use as breeding stocks. The technique would also 
lead to rapid identification of undesirable recessive 
traits which could be eliminated from the species. 
Chimeras 
DEFINITION 
A chimera is an animal comprised of cell lines 
from a variety of sources. They can be formed by 
fusing two or more early embryos or by adding extra 
cells to blastocysts. 
STATE OF THE ART 
Live chimeras between two species of mouse have 
been produced. Such young have four parents in- 
stead of two; hexaparental chimeras have also been 
produced. 
FUTURE 
Practical applications of chimera technolog\’ to 
livestock are not obvious at this stage of develop- 
ment. The main objective of this research is to pro- 
vide a genetic tool for better understanding of devel- 
opment, and maternal-fetal interactions. 
Recombinant DNA 
DEFINITION 
The introduction of foreign DNA into the germ- 
plasm. 
STATE OF THE ART 
The mechanics of changing the DN.A molecules of 
farm animals directly have not yet been worked out 
The plasmid methods used in bacteria may not he a[>- 
plicable. 
FUTl'RE 
None of these techniques, no matter how great the 
potential, will he of any use in animal hreecling until 
knowledge of genetics is greatly adxanced B<*fore 
one can alter genes, they must he identifi(*d. 
Prior to exploitation of recombinant DN.A technol- 
ogy in animal breeding, it is necessary to identify 
gene loci on chromosomes, i.e., genetic m.ipping. 
Work toward this goal has only i(*c»*nlly been initi- 
ated and rapid progress cannot he anticipated Multi- 
variate genetic determitiants of characteristics ol 
economic importance are antici|)at('d to he tin* rule 
