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Genes, Immediate-Early: Genes that show rapid and transient expression in the absence of de novo protein synthesis. The term was originally used exclusively for viral genes where immediate-early referred to transcription immediately following virus integration into the host cell. It is also used to describe cellular genes which are expressed immediately after resting cells are stimulated by extracellular signals such as growth factors and neurotransmitters.

An Introduction to Developmental Genetics

JoVE 5325

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.

 Developmental Biology

Gene Silencing with Morpholinos

JoVE 5326

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.

 Developmental Biology

An Overview of Genetic Analysis

JoVE 5540

An organism’s physical traits, or phenotype, are a product of its genotype, which is the combination of alleles (gene variants) inherited from its parents. To varying degrees, genes interact with each other and environmental factors to generate traits. The distribution of alleles and traits within a population is influenced by a number of factors, including natural selection, migration, and random genetic drift.In this video, JoVE introduces some of the foundational discoveries in genetics, from Gregor Mendel’s elucidation of the genetic basis of inheritance, to how natural processes affect allele distributions within populations, to the modern synthesis of biology that brought together Mendelian genetics and Darwinian evolution. We then review the questions asked by geneticists today regarding how genes influence traits, and some of the main tools used to answer these questions. Finally, several applications of techniques such as genetic crosses, screens and evolution experiments will be presented.


Zebrafish Microinjection Techniques

JoVE 5130

One of the major advantages to working with zebrafish (Danio rerio) is that their genetics can be easily manipulated by microinjection of early stage embryos. Using this technique, solutions containing genetic material or knockdown constructs are delivered into the blastomeres: the embryonic cells sitting atop the yolk of the newly fertilized egg. Delivery into the cytoplasm is achieved either through direct injection into the blastomere, or via natural cytoplasmic movements that occur after a solution is injected into the yolk. Successful genetic manipulations are usually followed by quantification of embryonic phenotypes in order to elucidate the genetic mechanisms of development. This video will provide an introduction to carrying out microinjections in zebrafish embryos. The discussion begins with a review of the essential tools for the technique, including the injection apparatus and the microinjector, which controls fluid movement with pressure pulses of air. Next, important preparatory steps are demonstrated, such as the pouring of agar plates to stabilize embryos during injection and calibration of the microinjection apparatus. The injection procedure is then presented along with tips on when and where injections should be performed. Finally, applications of the microinjection technique are discussed, including gene overexpression via mRNA inj

 Biology II

Drosophila melanogaster Embryo and Larva Harvesting and Preparation

JoVE 5094

Drosophila melanogaster embryos and larvae are easy to manipulate and develop rapidly by mechanisms that are analogous to other organisms, including mammals. For these reasons, many researchers utilize fly embryos and larvae to answer questions in diverse fields ranging from behavioral to developmental biology. Prior to experimentation, however, the embryos and larvae must first be collected. This video will first demonstrate how "egg-laying cups" are used to collect Drosophila embryos on agar plates. The harvest and dechorionation of embryos will then be described. Next, the video will demonstrate how to identify and manipulate Drosophila in one of the three larval stages that follow the embryo stage. Finally, examples of some of the ways in which fly embryos and larvae are used in biological research are provided.

 Biology I

An Introduction to Drosophila melanogaster

JoVE 5082

Drosophila melanogaster, also known as the fruit fly, is a powerful model organism widely used in biological research that has made significant contributions to the greater scientific community over the last century. First, this video introduces the fruit fly as an organism, including its physical characteristics, life cycle, environment, and diet. Next, the reasons why fruit flies make an excellent model organism are discussed. For example, fruit flies are inexpensive to maintain in the laboratory, have simplified genetics, and short generation times allow for quick experiments with high sample numbers. Then, key discoveries and important Drosophila researchers, such as Thomas Hunt Morgan are profiled. Finally, applications of Drosophila research, ranging from genetics to cardiac and neurological development and disease, are provided. This video serves as an overview of the highly-important and influential model organism that is Drosophila melanogaster.

 Biology I

An Introduction to the Zebrafish: Danio rerio

JoVE 5128

Zebrafish (Danio rerio) are small freshwater fish that are used as model organisms for biomedical research. The many strengths of these fish include their high degree of genetic conservation with humans and their simple, inexpensive maintenance. Additionally, gene expression can be easily manipulated in zebrafish embryos, and their transparency allows for observation of developmental processes. This overview video first introduces basic zebrafish biology, including their phylogeny, life cycle, and natural environment, before presenting the features that make them so useful in the lab. A brief history of zebrafish research is also provided through a review of major discoveries made in fish, ranging from the early establishment of methods for efficient genetic screening to the discovery of novel therapeutics for human diseases such as cancer. Finally, some of the many avenues of experimentation performed in zebrafish are discussed, including immunological and developmental studies.

 Biology II

An Introduction to Caenorhabditis elegans

JoVE 5103

Caenorhabditis elegans is a microscopic, soil-dwelling roundworm that has been powerfully used as a model organism since the early 1970’s. It was initially proposed as a model for developmental biology because of its invariant body plan, ease of genetic manipulation and low cost of maintenance. Since then C. elegans has rapidly grown in popularity and is now utilized in numerous research endeavors, from studying the forces at work during locomotion to studies of neural circuitry. This video provides an overview of basic C. elegans biology, a timeline of the many milestones in its short but storied history, and finally a few exciting applications using C. elegans as a model organism.

 Biology I

An Introduction to Cellular and Molecular Neuroscience

JoVE 5213

Cellular and molecular neuroscience is one of the newest and fastest growing subdisciplines in neuroscience. By investigating the influences of genes, signaling molecules, and cellular morphology, researchers in this field uncover crucial insights into normal brain development and function, as well as the root causes of many pathological conditions.

This video introduction to the fascinating world of cellular and molecular neuroscience begins with a timeline of landmark studies, from the discovery of DNA in 1953 to more recent breakthroughs like the cloning of ion channels. Next, key questions in the field are introduced, such as how genes influence neuron activity and how the nervous system is modified by experience. This is followed by brief descriptions of some prominent methods used to analyze genetic material in neurons, manipulate expression of genes, and visualize neurons and their parts. Finally, several applications of molecular and cellular neuroscience are presented to demonstrate how cellular and molecular approaches can be used to profile neuron populations and explore their functions.


Genetic Engineering of Model Organisms

JoVE 5327

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.

 Developmental Biology

An Introduction to Molecular Developmental Biology

JoVE 5328

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.

 Developmental Biology

An Introduction to Developmental Neurobiology

JoVE 5207

Developmental neuroscience is a field that explores how the nervous system is formed, from early embryonic stages through adulthood. Although it is known that neural progenitor cells follow predictable stages of proliferation, differentiation, migration, and maturation, the mechanisms controlling the progression through each stage are incompletely understood. Studying development is not only important for understanding how complex structures are assembled, but also for characterizing and treating developmental disorders. Since injury repair processes are similar to those that occur in development, this field is also a promising source of insight into when and how nervous system tissues regenerate.This video provides a brief overview of the field of developmental neuroscience, including some key experiments that have advanced our understanding of the mechanisms controlling the formation of early neural tissue and the further specialization of those cells into discrete subsets of neurons. The discussion focuses on prominent questions that developmental biologists are asking and then demonstrates some of the methods that they use to investigate these questions. Finally, applications of the techniques are presented to provide insight into what it means to be a developmental neuroscientist today. The range of experiments demo


DNA Methylation Analysis

JoVE 5550

Methylation at CpG dinucleotides is a chemical modification of DNA hypothesized to play important roles in regulating gene expression. In particular, the methylation of clusters of methylation sites, called “CpG islands”, near promoters and other gene regulatory elements may contribute to the stable silencing of genes, for example, during epigenetic processes such as genomic imprinting and X-chromosome inactivation. At the same time, aberrant CpG methylation has been shown to be associated with cancer.In this video, the biological functions and mechanisms of DNA methylation will be presented, along with various techniques used to identify methylation sites in the genome. We will then examine the steps of bisulfite analysis, one of the most commonly used methods for detecting DNA methylation, as well as several applications of this technique.


Induced Pluripotency

JoVE 5333

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.

 Developmental Biology

Zebrafish Reproduction and Development

JoVE 5151

The zebrafish (Danio rerio) has become a popular model for studying genetics and developmental biology. The transparency of these animals at early developmental stages permits the direct visualization of tissue morphogenesis at the cellular level. Furthermore, zebrafish are amenable to genetic manipulation, allowing researchers to determine the effect of gene expression on the development of a vertebrate with a high degree of genetic similarity to humans. This video provides a brief overview of the major phases of zebrafish development, with particular focus on the first 24 hours post fertilization (hpf). The discussion begins with a zygote consisting of a single cell, or blastomere, atop a large ball of yolk. Cleavage of the blastomere is then shown to produce an embryo containing thousands of cells within a matter of hours. Next, the dramatic cellular movements known as epiboly and gastrulation are explained, revealing how they contribute to reshaping a mass of cells into a moving embryo with a beating heart in just 1 day. The presentation follows embryo development through the hatching phase, when they become swimming, feeding larvae. Important considerations for caring for larvae are incorporated, including a brief review of how fish are raised to adulthood in a dedicated facility known as the nursery. Finally, the video concludes with some commo

 Biology II

An Overview of Epigenetics

JoVE 5549

Since the early days of genetics research, scientists have noted certain heritable phenotypic differences that are not due to differences in the nucleotide sequence of DNA. Current evidence suggests that these “epigenetic” phenomena might be controlled by a number of mechanisms, including the modification of DNA cytosine bases with methyl groups, the addition of various chemical groups to histone proteins, and the recruitment of protein factors to specific DNA sites via interactions with non-protein-coding RNAs.In this video, JoVE presents the history of important discoveries in epigenetics, such as X-chromosome inactivation (XCI), the phenomenon where an entire X-chromosome is silenced in the cells of female mammals. Key questions and methods in the field are reviewed, including techniques to identify DNA sequences associated with different epigenetic modifications. Finally, we discuss how researchers are currently using these techniques to better understand the epigenetic regulation of gene function.


An Introduction to Cell Death

JoVE 5649

Necrosis, apoptosis, and autophagic cell death are all manners in which cells can die, and these mechanisms can be induced by different stimuli, such as cell injury, low nutrient levels, or signaling proteins. Whereas necrosis is considered to be an “accidental” or unexpected form of cell death, evidence exists that apoptosis and autophagy are both programmed and “planned” by cells.In this introductory video, JoVE highlights key discoveries pertaining to cell death, including recent work done in worms that helped identify genes involved in apoptosis. We then explore questions asked by scientists studying cell death, some of which look at different death pathways and their interactions. Finally, several methods to assess cell death are discussed, and we note how researchers are applying these techniques in their experiments today.

 Cell Biology

An Introduction to the Laboratory Mouse: Mus musculus

JoVE 5129

Mice (Mus musculus) are an important research tool for modeling human disease progression and development in the lab. Despite differences in their size and appearance, mice share a distinct genetic similarity to humans, and their ability to reproduce and mature quickly make them efficient and economical candidate mammals for scientific study.

This video provides a brief overview of mice, both as organisms and in terms of their many advantages as experimental models. The discussion features an introduction to common laboratory mouse strains, including the nude mouse, whose genetic makeup renders them both hairless and immunodeficient. A brief history of mouse research is also offered, ranging from their first use in genetics experiments to Nobel prize-winning discoveries in immunology and neurobiology. Finally, representative examples of the diverse types of research that can be performed in mice are presented, such as classic behavioral tests like the Morris water maze and in-depth investigations of mammalian embryonic development.

 Biology II

An Introduction to the Chick: Gallus gallus domesticus

JoVE 5153

The chicken embryo (Gallus gallus domesticus) is an extremely valuable model organism for research in developmental biology, in part because most of their development takes place within an egg that is incubated outside of the mother. As a result, early developmental stages can be accessed, visualized and manipulated by simply creating a small hole in the eggshell. Since billions of chickens are raised worldwide for meat and egg production, scientists can easily and economically acquire large numbers of fertilized eggs throughout the year. Furthermore, chickens share significant genetic conservation with humans, so the genetic mechanisms that have been found to regulate chicken development are also relevant to our own biology. This video focuses on introducing the domesticated chicken as a scientific model. The discussion begins with a review of chicken phylogeny, revealing the features that make them amniotes, like other birds, reptiles, and mammals. Highlights from the millennia of chicken research will be presented, ranging from Aristotle’s postulates about the function of extra-embryonic membranes to more recent, Nobel-prize winning discoveries in neuroscience. Additionally, some current examples of studies performed in chicken embryos will be provided, such as in vivo tracking of cell movements during development and the recruitment of

 Biology II

An Introduction to Aging and Regeneration

JoVE 5337

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.

 Developmental Biology

Explant Culture for Developmental Studies

JoVE 5329

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.

 Developmental Biology

Transplantation Studies

JoVE 5336

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.

 Developmental Biology

C. elegans Development and Reproduction

JoVE 5110

Ceanorhabditis elegans is a powerful tool to help understand how organisms develop from a single cell into a vast interconnected array of functioning tissues. Early work in C. elegans traced the complete cell lineage and structure at the electron microscopy level, allowing researchers unprecedented insight into the connection between genes, development and disease. Appreciating the stereotyped development and reproductive program of C. elegans is essential to using this model organism to its experimental fullest. This video will give you a peek into the development of a worm from fertilization to hatching, and walk you though the life stages of the newly hatched larvae on its journey to reproductive maturity. The video will detail how the major axes are established, which founder cells give rise to what tissues in the developing embryo and how to discriminate between the four larval stages. Finally, you will learn how to set up a genetic cross and we"ll visit a few applications that manipulate the development and reproduction of C. elegans to experimental benefit.

 Biology I

An Introduction to Cell Motility and Migration

JoVE 5643

Cell motility and migration play important roles in both normal biology and in disease. On one hand, migration allows cells to generate complex tissues and organs during development, but on the other hand, the same mechanisms are used by tumor cells to move and spread in a process known as cancer metastasis. One of the primary cellular machineries that make cell movement possible is an intracellular network of myosin and actin molecules, together known as “actomyosin”, which creates a contractile force to pull a cell in different directions.In this video, JoVE presents a historical overview of the field of cell migration, noting how early work on muscle contraction led to the discovery of the actomyosin apparatus. We then explore some of the questions researchers are still asking about cell motility, and review techniques used to study different aspects of this phenomenon. Finally, we look at how researchers are currently studying cell migration, for example, to better understand metastasis.

 Cell Biology

An Introduction to Cognition

JoVE 5419

Cognition encompasses mental processes such as memory, perception, decision-making reasoning and language. Cognitive scientists are using a combination of behavioral and neuropsychological techniques to investigate the underlying neural substrates of cognition. They are interested in understanding how information is perceived, processed and how does it affect the final execution of behaviors. With this knowledge, researchers hope to develop new treatments for individuals with cognitive impairments. JoVE's introduction to cognition reviews several components of this phenomenon, such as perception, attention, language comprehension, etc. Key questions in the field of cognition will be discussed along with specific methods currently being used to answer these questions. Finally, specific studies that investigate different aspects of cognition using tools like functional Magnetic Resonance Imaging (fMRI) or Transcranial magnetic stimulation (TMS) will be explained.

 Behavioral Science

Testing For Genetically Modified Foods

JoVE 10044

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

Genetic modification of foods has been a controversial issue due to debated concerns over health and environmental safety. This experiment demonstrates technical understanding of how food DNA is genetically identified, allowing for educated decision making about the safety and potential dangers of using genetically modified organisms (GMOs) in food supplies. Polymerase Chain Reaction (PCR) is used to amplify food DNA to test for the presence of genetically modified DNA in food products. Presence of specific DNA bands is detected by using gel electrophoresis to pull extracted food DNA through a 3% agarose gel, a concentration dense enough to separate the bands of DNA containing the genetically modified DNA. Several controls are used in the electrophoresis procedure to ensure DNA is successfully extracted from test foods (plant primer), and to provide known examples of both genetically modified DNA (purchased genetically modified DNA) and non-genetically modified DNA (purchased certified non-GMO food control).

 Environmental Science

An Introduction to Cell Metabolism

JoVE 5652

In cells, critical molecules are either built by joining together individual units like amino acids or nucleotides, or broken down into smaller components. Respectively, the reactions responsible for this are referred to as anabolic and catabolic. These reactions require or produce energy typically in the form of a “high-energy” molecule called ATP. Together, these processes make up “Cell Metabolism,” and are hallmarks of healthy, living cells.JoVE’s introduction to cell metabolism briefly reviews the rich history of this field, ranging from early studies on photosynthesis to more recent discoveries pertaining to energy production in all cells. This is followed by a discussion of some key questions asked by scientists studying metabolism, and common methods that they apply to answer these questions. Finally, we’ll explore how current researchers are studying alterations in metabolism that accompany metabolic disorders, or that occur following exposure to environmental stressors.

 Cell Biology

An Introduction to Saccharomyces cerevisiae

JoVE 5081

Saccharomyces cerevisiae (commonly known as baker’s yeast) is a single-celled eukaryote that is frequently used in scientific research. S. cerevisiae is an attractive model organism due to the fact that its genome has been sequenced, its genetics are easily manipulated, and it is very easy to maintain in the lab. Because many yeast proteins are similar in sequence and function to those found in other organisms, studies performed in yeast can help us to determine how a particular gene or protein functions in higher eukaryotes (including humans). This video provides an introduction to the biology of this model organism, how it was discovered, and why labs all over the world have selected it as their model of choice. Previous studies performed in S. cerevisiae that have contributed to our understanding of important cellular processes such as the cell cycle, aging, and cell death are also discussed. Finally, the video describes some of the many ways in which yeast cells are put to work in modern scientific research, including protein purification and the study of DNA repair mechanisms and other cellular processes related to Alzheimer’s and Parkinson’s diseases.

 Biology I

Fundamentals of Breeding and Weaning

JoVE 10293

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN

Millions of mice and rats are bred for use in biomedical research each year. Worldwide, there are several large commercial breeding facilities that supply mice to research laboratories, but many facilities choose to also breed mice and rats in-house to reduce costs and increase research options. When breeding in the animal facility, researchers are able to manipulate the genetics of the animals, time the pregnancies to meet the needs of the research, and work with embryos and neonates as required. Mice and rats can be bred in a variety of schemes and methods. Technical procedures, such as the use of vaginal cytology, visualization of the vaginal area, and observation of copulatory plugs, have been developed to assist with the synchronization of breeding to correspond to research requirements. This manuscript is an overview of the basic fundamentals of mouse and rat breeding and technical procedures used. More detailed descriptions of the complex breeding schemes, and the full description of the methods for vaginal cytology, are available in the list of references.

 Lab Animal Research

Identification of Homologous Recombination Events in Mouse Embryonic Stem Cells Using Southern Blotting and Polymerase Chain Reaction

1Department of Pathology, Georgetown University Medical School, 2Lab of Animal Models and Functional Genomics (LAMFG), The Key Laboratory of Animal Vaccine & Protein Engineering, College of Veterinary Medicine, Hunan Agricultural University (HUNAU), 3College of Food Science and Technology, Hunan Agricultural University (HUNAU), 4Lab of Molecular Cardiology (LMC), National Heart, Lung, and Blood Institute (NHLBI)/National Institutes of Health (NIH), 5Transgenic Core, National Heart, Lung, and Blood Institute (NHLBI)/National Institutes of Health (NIH)

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JoVE 58467

 JoVE In-Press

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