China 
Africa 
Explore chapters and articles related to this topic
Animal Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Animal cloning is the process by which an entire organism is reproduced from a single cell taken from the parent organism and in a genetically identical manner. Cloning in biotechnology refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms. Scientists have been attempting to clone animals for a very long time. Many of the early attempts came to nothing. The first successful result in animal cloning was seen when tadpoles were cloned from frog embryonic cells in 1952. This was the first vertebrate to be cloned. This cloning was done by the process of nuclear transfer. The tadpoles that were created by this method did not survive to grow into mature frogs, but it was a major breakthrough nevertheless. After this, using the process of nuclear transfer of embryonic cells, scientists managed to produce clones of mammals. Again, the cloned animals did not live very long (Figure 7.7).
Dedifferentiation as a cell source for organ regeneration
Published in David M. Gardiner, Regenerative Engineering and Developmental Biology, 2017
It is evident that molecular events, particularly changes in gene expression, must accompany the dramatic morphological and biochemical changes observed during dedifferentiation, as viewed during depigmentation of dorsal iris cells or the cellularization of muscle fibers. Thus, as with many other biological processes, the study of dedifferentiation has extended to the molecular level. It is a common occurrence that during regenerative processes, one observes diminishing expression of certain gene products associated with fully differentiated cells, whereas new gene markers, usually associated with less differentiated cells, appear in the dedifferentiated cells (Sugimoto et al. 2011). Thus, the process of natural cell dedifferentiation can be compared with the process termed cellular or nuclear reprogramming, which is associated with changes in gene expression that take place during induced cell dedifferentiation. In its beginning, the induction of dedifferentiation was pioneered by Gurdon’s nuclei-transfer experiments, showing that the nuclei of a mature cell could be reprogrammed to an embryological state (Gurdon and Wilmut 2011). Follow-up of these experiments gave rise to the successful cloning of animals by nuclear transfer from adult (differentiated) cells, such as shown by the cloning of the sheep Dolly. These experiments gave rise to studies directed at identifying the factors responsible for the reprogramming response. Once again, the link with cancer is evident, since oncogenesis is viewed as a disease in which cells are reprogrammed to an embryonic-like state (Halley-Stott et al. 2013).
Human Embryos, Human Beings: A Scientific and Philosophical Approach
Published in The New Bioethics, 2021
According to the Condics, these factors can be summed as requiring organisation of an intrinsic whole, by which a developing thing anticipates its final form. Enter science, which provides the observational evidence for determining whether this organization is present in the embryo. More specifically, this requires ‘uniquely human structures and operations’ (p. 185) to be observed to establish the embryo as a human being. Chapter eight is dedicated to a detailed examination of difficult cases that help to validate both the criterion of organization, and to develop guiding principles for its application. These cases include cells reprogrammed to be pluripotent, complete hydatidiform moles, and embryos with an extra copy of DNA. Three guiding questions are proposed for determining the ontological status of entities that are being manipulated in some way, by nature or experiment: firstly, whether there is an ongoing developmental trajectory; secondly, if the alteration prevents a developmental trajectory; and finally, if the alteration produces a new entity or an entity in a new state. An entire chapter is dedicated to an examination of altered nuclear transfer, which uses somatic cell nuclear transfer to produce pluripotent cells that can differentiate into any cell type of the body, without being an embryo. The examples show that a purely philosophical or scientific approach to determining status as a human being is inadequate – a combined effort is required.