Embryo Project Encyclopedia

Rosalind Elsie Franklin worked with X-ray crystallography at King's College London, UK, and she helped determine the helical structure of DNA in the early 1950s. Franklin's research helped establish molecular genetics, a field that investigates how heredity works on the molecular level. The discovery of the structure of DNA also made future research possible into the molecular basis of embryonic development, genetic disorders, and gene manipulation.

Human pluripotent stem cells are valued for their potential to form numerous specialized cells and for their longevity. In the US, where a portion of the population is opposed to destruction of human embryos to obtain stem cells, what avenues are open to scientists for obtaining pluripotent cells that do not offend the moral sensibilities of a significant number of citizens? It is this question that the official position paper, or white paper, "Alternative Sources of Human Pluripotent Stem Cells," published in May 2005 by the President's Council on Bioethics under the chairmanship of Leon Kass, seeks to answer. Three experts external to the council, Andrew Fire from the Stanford University School of Medicine, Markus Grompe of the Oregon Health and Science University, and Janet Rossant from the Samuel Lunenfeld Research Institute in Toronto, also reviewed the white paper prior to publication.

Matthew Kaufman was a professor of anatomy at the University of Edinburgh, in Edinburgh, UK, who specialized in mouse anatomy, development, and embryology during the late twentieth century. According to the The Herald, he was the first, alongside his colleague Martin Evans, to isolate and culture embryonic stem cells. Researchers initially called those cells Evans-Kaufman cells. In 1992, Kaufman published The Atlas of Mouse Development, a book that included photographs of mice development and mice organs over time. Kaufman also wrote books about UK medical history, phrenology, or the study of craniums as an indicator of character or mental ability, and medical teaching in the eighteenth and nineteenth centuries. Kaufman’s anatomical records and experiments in mouse development contributed to genetic engineering, embryology, and anatomy.

The San Diego Zoo Institute for Conservation Research (SDZICR) in San Diego, California, is a research organization that works to generate, use, and share information for the conservation of wildlife and their habitats. In 1975, Kurt Benirschke, a researcher at the University of California, San Diego (UCSD) who studied human and animal reproduction, and Charles Bieler, the director of the San Diego Zoo, collaborated to form the Center for Reproduction of Endangered Species (CRES). In 2009, the San Diego Zoo announced the creation of SDZICR, which expanded and replaced CRES, to provide central organization and management of scientific programs at the San Diego Zoo. By 2004, Allison Alberts was the director of research and for more than a decade oversaw the SDZICR's many research initiatives, including the collection and storage of genetic and reproductive information of rare and endangered animal and plant species.

In the late 1990s researchers Yuk Ming Dennis Lo and his colleagues isolated fetal DNA extracted from pregnant woman’s blood. The technique enabled for more efficient and less invasive diagnoses of genetic abnormalities in fetuses, such as having too many copies of chromosomes. Lo’s team published their results in 1997’s “Presence of Fetal DNA in Maternal Plasma and Serum.” The results led to developments of clinical tests that can access fetal genetic information and detect genetic abnormalities before birth without the significant risks that can potentially harm the fetus associated with invasive genetic testing techniques.

In the twentieth and early twenty-first centuries, Gail Roberta Martin specialized in biochemistry and embryology, more specifically cellular communication and the development of organs. In 1981, she named any cell taken from inside a human embryo at the blastocyst stage an “embryonic stem cell”. During development, an embryo goes through the blastocyst stage just before it implants in the uterus. Embryonic stem cells are useful for experiments because they are self-renewing and able to develop into almost any cell type in the body. Martin later identified a key chemical component in limb development and continues to study embryogenesis, or the growth of embryos over time. Martin’s work on embryonic stem cells has allowed scientists to further research and treat human diseases, and her study of how organs form has helped scientists learn about the healthy growth of embryos.

In February 1953, Linus Pauling and Robert Brainard Corey, two scientists working at the California Institute of Technology in Pasadena, California, proposed a structure for deoxyribonucleic acid, or DNA, in their article “A Proposed Structure for the Nucleic Acids,” henceforth “Nucleic Acids.” In the article, Pauling and Corey suggest a model for nucleic acids, including DNA, that consisted of three nucleic acid strands wound together in a triple helix. “Nucleic Acids” was published in Proceedings of the National Academy of Sciences shortly after scientists came to the consensus that genes, the biological factors that control how organisms develop, contained DNA. Though scientists proved Pauling and Corey’s model incorrect, “Nucleic Acids” helped scientists understand DNA’s structure and function as genetic material.

Mary-Claire King studied genetics in the US in the twenty-first century. King identified two genes associated with the occurrence of breast cancer, breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2). King showed that mutated BRCA1 and BRCA2 genes cause two types of reproductive cancer, breast and ovarian cancer. Because of King’s discovery, doctors can screen women for the inheritance of mutated BRCA1 and BRCA2 genes to evaluate their risks for breast and ovarian cancer. King also demonstrated the genetic similarities between chimpanzees and humans and helped to identify victims of human rights abuses using genetics. King's identification of the BRCA genes and their relationship to breast and ovarian cancer, both reproductive cancers, has allowed physicians to screen thousands of women for the genes and for those women to choose to undergo preventative cancer treatment to lower their risk of cancer.

In 2015, Junjiu Huang and his colleagues reported their attempt to enable CRISPR/cas 9-mediated gene editing in nonviable human zygotes for the first time at Sun Yat-Sen University in Guangzhou, China. Their article, CRISPR /Cas9-mediated Gene Editing in Human Tripronuclear Zygotes, was published in Protein and Cell. Nonviable zygotes are sperm-fertilized eggs that cannot develop into a fetus. Researchers previously developed the CRISPR/cas 9 gene editing tool, which is a system that originated from bacteria as a defense mechanism against viruses. In their article, Huang and his team demonstrate that CRISPR/cas-9 gene editing can be used to correct a mutation in zygotes, or sperm-fertilized egg cells. However, they report that using CRISPR/cas 9 to edit those nonviable human zygotes led to off-target changes and, therefore, to unintended mutations in the human genome. Before Huang and his colleagues' experiment, CRISPR/cas 9 had never been used on human zygotes. In their article, Huang and his colleagues demonstrated the need to improve CRISPR/cas 9 gene editing accuracy before using it for gene therapy to treat and correct genetic diseases in humans.