3 Types of Cloning • Transgenic (gene) cloning • Therapeutic (stem cell) cloning • Reproductive (organism) cloning)
Transgenic • Organisms that contain another species’ genes within their chromosomes • First transgenic organisms were bacteria • Scientists around the world use customized transgenic animals for their own research
Transgenic Benefits of transgenic animals • Animal models • Pharmaceutical production • Organ donors • Livestock improvement
Production of transgenic animals • The transgene (which contains the DNA the scientist wants to transfer) is introduced into a single-cell embryo • The embryo is transferred to a surrogate mother of the same strain • Success rate is low (10%-30%) in mice • Success rate decreases in mammals
Transgenic Care of transgenic animals • Most do not require special care • Some develop a susceptibility to disease Government’s view • May patent new organisms • Regulated by NIH
Future of transgenic animals • Current research limited to transferring a small amount of genes at a time • Much work remains to be done to fine-tune techniques • Possible effects of foreign DNA remains a concern • The use of transgenic models is an established part of biomedical research
Therapeutic Cloning • Procedure used to produce embryonic stem cells that theoretically can be used to treat diseases • Goal of therapeutic cloning is to produce embryonic stem cells • In therapeutic cloning, the embryo is not placed in a surrogate, but rather, undergoes cell division in the lab until it reaches blastocyst stage.
Therapeutic cloning • Types of Stem cells • Embryonic • Adult • Amniotic
Human stem cell research • 2001 legislation allowed federal funding of research using 64 existing human embryonic stem cells • Same legislation declared no federal funds for additional research. • Researchers must use existing human stem cell lines for research or find private funding sources
Therapeutic • Creation of embryonic stem cells does not always use fertilized egg • On the other hand, it does have the potential to become a living thing if transplanted into the uterus • Question – is life destroyed if the stem cells are removed from the blastocyst four days later?
Therapeutic • Real advantage of stem cells – permits the production of perfect-match tissue • Scientists have found that embryonic stem cells pick up cues from neighboring cells and differentiate into that cell type • Scientists hope stem cells will be used to treat heart disease, Parkinson’s disease, other disorders of the nervous system
Reproductive Cloning • Goal of reproductive cloning is to create a new organism, human or animal • Clone = precise genetic copy • Reproductive cloning is really somatic cell nuclear transfer (SCNT) • Dolly the sheep – first cloned mammal in 1997 • Very few scientists believe human cloning (reproductive cloning) should be permitted
Reproductive cloning • Obstacles to reproductive cloning using animals • Success rate very low • Vast majority of problems occur during fetal development • Additional problems show up after birth and years later • “Large offspring syndrome” = cloned newborns 20-30% larger than usual, making it hard to deliver unborn babies