An Introduction to Saccharomyces cerevisiae
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.…
An Introduction to Drosophila melanogaster
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.…
An Introduction to Caenorhabditis elegans
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.…
Research performed in the yeast Saccharomyces cerevisiae has significantly improved our understanding of important cellular phenomona such as regulation of the cell cycle, aging, and cell death. The many benefits of working with S. cerevisiae include the facts that they are inexpensive to grow in the lab and that many ready-to-use strains are now commercially available. Nevertheless, proper maintenance of this organism is critical for successful experiments. This video will provide an overview of how to grow and maintain S. cerevisiae in the lab. Basic concepts required for monitoring the proliferation of a yeast population, such as how to generate a growth curve using a spectrophotometer, are explained. This video also demonstrates the hands-on techniques required to maintain S. cerevisiae in the lab, including preparation of media, how to start a new culture of yeast cells, and how to store those cultures. Finally, the video shows off some of the ways these handling and maintenance techniques are applied in scientific research.…
Drosophila melanogaster, commonly known as fruit flies, are a frequently used model organism for life science research. Although starting a collection of these critters may seem as easy as leaving a banana on your kitchen counter for too long, a productive fly colony in the lab requires careful husbandry and maintenance.
This video demonstrates the necessary steps for maintaining a healthy fly stock. The overview begins with the preparation and storage of the yeast and sugar-containing media on which flies feed. Next, the vessels most commonly used for housing Drosophila are shown, as well as how and when to move flies between these containers. Finally, the presentation also includes examples of the ways in which housing and feeding conditions are manipulated for biological experiments. …
C. elegans Maintenance
Ceanorhabditis elegans has been, and is still, used to great success as a model organism for studying a variety of developmental, genetic, molecular and even physical phenomena. In order to use C. elegans to its full potential, proper care and attention to the basic maintenance of this powerful organism is essential.
In this video you will learn the basic housing and feeding requirements of C. elegans, how to correctly handle and manipulate worms using a worm pick and how to freeze and recover important worm stocks. Towards the end of the video we will visit a few applications of modifying the housing, feeding and manipulation of these important animals.…
Saccharomyces cerevisiae is a species of yeast that is an extremely valuable model organism. Importantly, S. cerevisiae is a unicellular eukaryote that undergoes many of the same biological processes as humans. This video provides an introduction to the yeast cell cycle, and explains how S. cerevisiae reproduces both asexually and sexually Yeast reproduce asexually through a process known as budding. In contrast, yeast sometimes participate in sexual reproduction, which is important because it introduces genetic variation to a population. During environmentally stressful conditions, S. cerevisiae will undergo meiosis and form haploid spores that are released when environmental conditions improve. During sexual reproduction, these haploid spores fuse, ultimately forming a diploid zygote. In the lab, yeast can be genetically manipulated to further understand the genetic regulation of the cell cycle, reproduction, aging, and development. Therefore, scientists study the reproduction of yeast to gain insight into processes that are important in human biology.…
Drosophila Development and Reproduction
One of the many reasons that make Drosophila an extremely valuable organism is that the molecular, cellular, and genetic foundations of development are highly conserved between flies and higher eukaryotes such as humans. Drosophila progress through several developmental stages in a process known as the life cycle and each stage provides a unique platform for developmental research. This video introduces each stage of the Drosophila life cycle and details the physical characteristics and major developmental events that occur during each stage. Next, the video discusses the genetic regulation of pattern formation, which is important for establishing the body plan of the organism and specifying individual tissues and organs. In addition, this video gives an overview of Drosophila reproduction, and how to use the reproductive characteristics of Drosophila to set up a genetic cross. Finally, we discuss examples of how the principles of Drosophila development and reproduction can be applied to research. These applications include RNA interference, behavioral assays of mating behaviors, and live imaging techniques that allow us to visualize development as a dynamic process. Overall, this video highlights the importance of understanding development and reproduction in Drosophila, and how this knowledge can be used to understand development in other organisms.…
C. elegans Development and Reproduction
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.…
Isolating Nucleic Acids from Yeast
One of the many advantages to using yeast as a model system is that large quantities of biomacromolecules, including nucleic acids (DNA and RNA), can be purified from the cultured cells.
This video will address the steps required to carry out nucleic acid extraction. We will begin by briefly outlining the growth and harvest, and lysis of yeast cells, which are the initial steps common to the isolation of all biomacromolecules. Next, we will discuss two unique purification methods for the separation of nucleic acids: column binding and phase separation. Additionally, we will demonstrate several ways in which these methods are applied in the laboratory, including the preparation of nucleic acids for molecular biology techniques such as PCR and southern blotting, quantification of gene expression in response to environmental stimuli, and purification of large amounts of recombinant proteins.…
Drosophila Larval IHC
Immunohistochemistry (IHC) is a technique used to visualize the presence and location of proteins within tissues. Drosophila larvae are particularly amenable to IHC because of the ease with which they can be processed for staining. Additionally, the larvae are transparent, meaning that some tissues can be visualized without the need for dissection.
In IHC, proteins are ultimately detected with antibodies that specifically bind to “epitopes” within the protein of interest. In order to preserve these epitopes, tissues must be fixed prior to staining. Furthermore, in order for antibodies to penetrate membranes, cells must be permeabilized with detergents. This video article offers a detailed view of the reagents, tools, and procedures necessary for the staining of dissected larval tissues, including fixation, blocking, and staining steps. Also featured is a demonstration of tissue mounting techniques for fluorescence microscopy. Finally, examples of the broad range of applications for these techniques (and some variations upon them) are provided.…
RNAi in C. elegans
RNA interference (RNAi) is a widely used technique in which double stranded RNA is exogenously introduced into an organism, causing knockdown of a target gene. In the nematode, C. elegans, RNAi is particularly easy and effective because it can be delivered simply by feeding the worms bacteria that express double stranded RNA (dsRNA) that is complementary to a gene of interest. First, this video will introduce the concept of RNA interference and explain how it causes targeted gene knockdown. Then, we will demonstrate a protocol for using RNAi in C. elegans, which includes preparation of the bacteria and RNAi worm plates, culturing of the worms, and how to assess the effects of RNAi on the worms. RNAi is frequently used to perform reverse genetic screens in order to reveal which genes are important to carry out specific biological processes. Furthermore, automated reverse genetic screens allow for the efficient knockdown and analysis of a large collection of genes. Lastly, RNAi is often used to study the development of C. elegans. Since its discovery, scientists have used RNAi to make tremendous progress on the understanding of many biological phenomena.…
Yeast Transformation and Cloning
S. cerevisiae are unicellular eukaryotes that are a commonly-used model organism in biological research. In the course of their work, yeast researchers rely upon the fundamental technique of transformation (the uptake of foreign DNA by the cell) to control gene expression, induce genetic deletions, express recombinant proteins, and label subcellular structures.
This video provides an overview of how and why yeast transformation is carried out in the lab. The important features of yeast plasmids will be presented, along with the procedure required to prepare yeast cells to incorporate new plasmids. The presentation also includes a step-by-step protocol for the lithium acetate method of yeast transformation. Finally, examples of the many applications of this essential technique will be provided. …
Drosophila melanogaster Embryo and Larva Harvesting and Preparation
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.…
C. elegans Chemotaxis Assay
Chemotaxis is a process in which cells or organisms move in response to a chemical stimulus. In nature, chemotaxis is important for organisms to sense and move toward food sources and move away from stimuli that may be toxic or harmful. Chemotaxis is also important at the cellular level. For example, chemotaxis is required for the movement of sperm toward an egg prior to fertilization. In the lab, chemotaxis is frequently examined in the nematode, C. elegans, which is known to migrate towards food sources in soil, but away from toxins such as heavy metals, substances with a low pH, and detergents. This video demonstrates how to perform a chemotaxis assay, which includes preparing the chemotaxis plates and the worms, running the assay, and analyzing the data. Then, we discuss examples of how chemotaxis assays can be used in C. elegans as a tool to understand learning and memory, olfactory adaptation, and neurological disease such as Alzheimer"s disease. Chemotaxis experiments in C. elegans have near-limitless possibilities for learning more about the cellular and genetic mechanisms of many biological processes, and may lead to a greater understanding of human biology, development, and disease.…