An Introduction to Developmental Genetics
Development is the complex process through which a single-celled embryo transforms into a multicellular organism. Developmental processes are guided by information encoded in an organism's DNA, and geneticists are trying to understand how this information leads to a fully formed organism.
This video reviews seminal research in the field of developmental biology, including the identification of specific genes that control various embryonic processes. An introduction to the major questions asked by developmental geneticists, and the prominent methods used to answer them, is also provided. Finally, several applications of these prominent methods are discussed, in order to show specific experiments currently being performed in this field.…
Gene Silencing with Morpholinos
Morpholino-mediated gene silencing is a common technique used to study roles of specific genes during development. Morpholinos inhibit gene expression by hybridizing to complementary mRNAs. Due to their unique chemistry, morpholinos are easy to produce and store, which makes them remarkably cost effective compared to other gene silencing methods.
This video reviews proper experimental design when using these oligonucleotides. Following that, an explanation of morpholino microinjection techniques in zebrafish and the analysis of resulting phenotypes will be discussed. Finally, we showcase examples of specific applications where morpholino technology is used to model developmental disorders or to study tissue regeneration.…
Genetic Engineering of Model Organisms
Transgenesis, or the use of genetic engineering to alter gene expression, is widely used in the field of developmental biology. Scientists use a number of approaches to alter the function of genes to understand their roles in developmental processes. This includes replacement of a gene with a nonfunctional copy, or adding a visualizable tag to a gene that allows the resultant fusion protein to be tracked throughout development.
In this video, the viewers will learn about the principles behind transgenesis, as well as the basic steps for introducing genetic constructs into an animal and targeting genes of interest. This is followed by the discussion of a protocol to create knockout mice. Lastly, some specific applications of transgenic technologies in the field of developmental biology will be reviewed.…
An Introduction to Molecular Developmental Biology
Molecular signals play a major role in the complex processes occurring during embryonic development. These signals regulate activities such as cell differentiation and migration, which contribute to the formation of specific cell types and structures. The use of molecular approaches allows researchers to investigate these physical and chemical mechanisms in detail.
This video will review a brief history of the study of molecular events during development. Next, key questions asked by molecular developmental biologists today will be reviewed, followed by a discussion of several prominent methods used to answer these questions, such as staining, explant culture, and live-cell imaging. Finally, we will look at some current applications of these techniques to the study of developmental biology.…
Explant Culture for Developmental Studies
Explant culture is a technique in which living cells or tissues are removed from an embryo for continued development outside of the organism. This ex vivo approach allows researchers to manipulate and observe developing tissues in ways that are not possible in vivo. Once established, explant culture is frequently used to understand the role of genes and signaling molecules in organogenesis.
This video will first introduce the basic principles of explant culture and demonstrate a protocol to isolate and grow explanted mammalian tissues. Common genetic and molecular methods of manipulating explant cultures will then be discussed. Finally, the viewers will learn about how explant techniques are currently being applied to study organ development.…
Whole-Mount In Situ Hybridization
Whole-mount in situ hybridization (WMISH) is a common technique used for visualizing the location of expressed RNAs in embryos. In this process, synthetically produced RNA probes are first complementarily bound, or "hybridized," to the transcripts of target genes. Immunohistochemistry or fluorescence is then used to detect these RNA hybrids, revealing spatial and temporal patterns of gene expression. Unlike traditional in situ hybridization techniques, which require thin tissue sections whose images will need to be computationally reassembled, the whole-mount technique allows gene expression patterns to be assessed over the entire embryo or structure. This video will introduce the basic concepts of whole mount staining and detail key procedural steps, including probe design and production, embryo fixation and staining, and post-hybridization signal detection. Viewers will then learn about how developmental biologists are applying WMISH to current research studies.…
An Introduction to Stem Cell Biology
Cells that can differentiate into a variety of cell types, known as stem cells, are at the center of one of the most exciting fields of science today. Stem cell biologists are working to understand the basic mechanisms that regulate how these cells function. These researchers are also interested in harnessing the remarkable potential of stem cells to treat human diseases.
Here, JoVE presents an introduction to the captivating world of stem cell biology. We begin with a timeline of landmark studies, from the first experimental evidence for hematopoietic stem cells in the 1960s, to more recent breakthroughs like induced pluripotent stem cells. Next, key questions about stem cell biology are introduced, for example: How do these cells maintain their unique ability to undergo self-renewal? This is followed by a discussion of some prominent methods used to answer these questions. Finally, several experiments are presented to demonstrate the use of stem cells in regenerative medicine.…
Embryonic Stem Cell Culture and Differentiation
Culturing embryonic stem (ES) cells requires conditions that maintain these cells in an undifferentiated state to preserve their capacity for self-renewal and pluripotency. Stem cell biologists are continuously optimizing methods to improve the efficiency of ES cell culture, and are simultaneously trying to direct the differentiation of ES cells into specific cell types that could be used in regenerative medicine.
This video describes the basic principles of ES cell culture, and demonstrates a general protocol to grow and passage ES cells. We also take a closer look at the hanging drop method, which is used to differentiate ES cells. Finally, this video will describe a few applications of ES cell culture and differentiation techniques, including a method used to generate functional heart muscle cells in vitro.…
Induced pluripotent stem cells (iPSCs) are somatic cells that have been genetically reprogrammed to form undifferentiated stem cells. Like embryonic stem cells, iPSCs can be grown in culture conditions that promote differentiation into different cell types. Thus, iPSCs may provide a potentially unlimited source of any human cell type, which is a major breakthrough in the field of regenerative medicine. However, more research into the derivation and differentiation of iPSCs is still needed to actually use these cells in clinical practice. This video first introduces the fundamental principles behind cellular reprogramming, and then demonstrates a protocol for the generation of iPSCs from differentiated mouse embryonic fibroblasts. Finally, it will discuss several experiments in which scientists are improving or applying iPSC generation techniques.…
An Introduction to Organogenesis
Organogenesis is the process by which organs arise from one of three germ layers during the later stages of embryonic development. Researchers studying organogenesis want to better understand the genetic programs, cell-cell interactions, and mechanical forces involved in this process. Ultimately, scientists hope to use this knowledge to create therapies and artificial organs that will help treat human diseases.
This video offers a comprehensive overview of organogenesis, starting with historical highlights describing the breakthrough studies done in the 1800\'s, all the way to the first human surgery using tissue-engineered organs performed in 2008. Next, key questions asked by developmental biologists are introduced, followed by a discussion of how tissue transplantations, imaging, and in vitro culture techniques can be used to answer these queries. Finally, we describe how these methods are currently being employed in developmental biology laboratories.…
Fate mapping is a technique used to understand how embryonic cells divide, differentiate, and migrate during development. In classic fate mapping experiments, cells in different areas of an embryo are labeled with a chemical dye and then tracked to determine which tissues or structures they form. Technological improvements now allow for individual cells to be marked and traced throughout embryonic development and adulthood.
This video reviews the concepts behind fate mapping, and then details a fate mapping protocol in zebrafish using photoactivatable fluorescent proteins. Finally, specific applications and modifications of this unique technique are discussed.…
Many developmental biologists are interested in the molecular signals and cellular interactions that induce a group of cells to develop into a particular tissue. To investigate this, scientists can use a classic technique known as transplantation, which involves tissue from a donor embryo being excised and grafted into a host embryo. By observing how transplanted tissues develop in host environments, scientists have started to dissect the molecular pathways underlying development. In this video, we first look at the role of cellular interactions in development, and move on to a basic transplantation protocol. Finally, some specific developmental studies utilizing this technique are discussed, which examine the effect of tissue transplantation on the fate of donor and host tissue.…
An Introduction to Aging and Regeneration
Tissues are maintained through a balance of cellular aging and regeneration. Aging refers to the gradual loss of cellular function, and regeneration is the repair of damaged tissue generally mediated by preexisting adult or somatic stem cells. Scientists are interested in understanding the biological mechanisms behind these two complex processes. By doing so, researchers may be able to use somatic stem cells to treat degenerative diseases and develop therapies that could delay the effects of aging. In this video, we provide a brief history of the field of aging and regeneration, touching upon observations made in ancient Greece, as well as modern-day experiments. Some of the questions being asked in this field, and the prominent methods being used by biologists to answer them, are then explored. Finally, we look at a few specific experiments being conducted in today\'s aging and regeneration research laboratories.…
Invertebrate Lifespan Quantification
Many animals naturally stop growing upon reaching adulthood, after which they undergo aging or "senescence" until dying. The amount of time between an organism\'s birth and death is called its lifespan, which can be influenced by various biological and environmental factors. By exposing organisms to different growth conditions, scientists can better understand the factors affecting lifespan. Flies and worms are ideal organisms to perform such experiments, given their short generation time and simple culture requirements. This video provides a brief overview of the factors affecting aging, and goes on to describe basic protocols for invertebrate lifespan quantification experiments. Finally, three research applications of lifespan quantification will be discussed. These experiments explore the effects of diverse factors, such as temperature, drugs, pathogens, and diet, on lifespan.…
Tissue Regeneration with Somatic Stem Cells
Somatic or adult stem cells, like embryonic stem cells, are capable of self-renewal but demonstrate a restricted differentiation potential. Nonetheless, these cells are crucial to homeostatic processes and play an important role in tissue repair. By studying and manipulating this cell population, scientist may be able to develop new regenerative therapies for injuries and diseases.
This video first defines somatic stem cells, and then explores the role these cells play in tissue regeneration. This is emphasized in a description of a protocol that isolates muscle satellite cells and uses them to repair muscle damage in a mouse model of muscular dystrophy. Finally, we discuss specific tissue regeneration studies utilizing somatic stem cells.…