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October, 2006
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Mice: The common name for the genus Mus.

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 …

 Developmental Biology

Evolutionary Relationships- Concept

JoVE 10561

Humans have been attempting to properly classify living things since Aristotle made the first attempt during the 4th century BC. Aristotle’s system was improved upon during the Renaissance and then, subsequently, by Carolus Linnaeus in the mid 1700’s. These more formal classification and organization systems grouped species by their physical similarity to one another. For example,…

 Lab Bio

High-frequency Ultrasound Imaging of the Abdominal Aorta

JoVE 10397

Source: Amelia R. Adelsperger, Evan H. Phillips, and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana

High-frequency ultrasound systems are used to acquire high resolution images. Here, the use of a state-of-the-art system will be demonstrated to image the morphology and …

 Biomedical Engineering


JoVE 10909

Gastrulation establishes the three primary tissues of an embryo: the ectoderm, mesoderm, and endoderm. This developmental process relies on a series of intricate cellular movements, which in humans transforms a flat, “bilaminar disc” composed of two cell sheets into a three-tiered structure. In the resulting embryo, the endoderm serves as the bottom layer, and stacked directly above it is the intermediate mesoderm, and then the uppermost ectoderm. Respectively, these tissue strata will form components of the gastrointestinal, musculoskeletal and nervous systems, among other derivatives. Depending on the species, gastrulation is achieved in different ways. For example, early mouse embryos are uniquely shaped and appear as “funnels” rather than flat discs. Gastrulation thus produces a conical embryo, arranged with an inner ectoderm layer, outer endoderm, and the mesoderm sandwiched in between (similar to the layers of a sundae cone). Due to this distinct morphological feature of mice, some researchers study other models, like rabbit or chicken—both of which develop as flat structures—to gain insights into human development. One of the main morphological features of avian and mammalian gastrulation is the primitive streak, a groove that appears down the vertical center of the embryo, and through which cells migrate t

 Core: Biology

The Resting Membrane Potential

JoVE 10845

The relative difference in electrical charge, or voltage, between the inside and the outside of a cell membrane, is called the membrane potential. It is generated by differences in permeability of the membrane to various ions and the concentrations of these ions across the membrane.

The membrane potential of a cell can be measured by inserting a microelectrode into a cell and comparing the charge to a reference electrode in the extracellular fluid. The membrane potential of a neuron at rest—that is, a neuron not currently receiving or sending messages—is negative, typically around -70 millivolts (mV). This is called the resting membrane potential. The negative value indicates that the inside of the membrane is relatively more negative than the outside—it is polarized. The resting potential results from two major factors: selective permeability of the membrane, and differences in ion concentration inside the cell compared to outside. Cell membranes are selectively permeable because most ions and molecules cannot cross the lipid bilayer without help, often from ion channel proteins that span the membrane. This is because the charged ions cannot diffuse through the uncharged hydrophobic interior of membranes. The most common intra- and extracellular ions found in the nervous tissue are potassium (K+), sodium (Na+…

 Core: Biology


JoVE 10653

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly inclusive categories with Latin names. The smallest units of taxonomy, species and genus, are used to assign a formal, taxonomic name to each species in a system. This classification system, referred to as binomial nomenclature, was formalized by Carolus Linnaeus in the 18th century. The hierarchy that Carolus Linnaeus first proposed is still used today, although it has been expanded upon. The order of ranking—from the highest or largest group to the smallest or most specific—is as follows: domain, kingdom, phylum, class, order, family, genus, and species. Beginning from the smallest unit of taxonomy, similar species are grouped into the same genus. For example, the arctic hare and the black-tailed jackrabbit both belong to the genus Lepus; however, they belong to different species—arcticus and californicus, respectively. Within an organism’s taxonomic name, both the genus and species are italicized, and the first letter of the genus is capitalized. This two-part format for naming and categorizing specific organisms is referred to as binomial nomenclature. Members of the same genus belong to the same family. For example, hares and rabbits belong t

 Core: Biology

Measuring Biodiversity- Concept

JoVE 10596

Diverse ecosystems are important for the health of the planet and our survival as humans; it is therefore incredibly important for us to understand and measure biodiversity, which is defined as the variability among living organisms in an ecosystem. Biodiversity can be measured at many different levels including genetic, species, community, and ecosystem. One way to measure biodiversity is to …

 Lab Bio

Combined SPECT and CT Imaging to Visualize Cardiac Functionality

JoVE 10396

Source: Alycia G. Berman, James A. Schaber, and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana

Here we will demonstrate the fundamentals of single-photon emission computed tomography/computed tomography (SPECT/CT) imaging using mice. The technique involves injecting a…

 Biomedical Engineering

Compound Administration I

JoVE 10198

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

As many research protocols require that a substance be injected into an animal, the route of delivery and the amount of the substance must be accurately determined. There are several routes of administration available in the mouse and rat. …

 Lab Animal Research

Compound Administration II

JoVE 10388

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

Compound administration is often an integral component of an animal study. Many factors need to be evaluated to ensure that the compound is delivered correctly. The route of administration affects the mechanisms of…

 Lab Animal Research
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