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October, 2006
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Sea Urchins: Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying Fertilization and Embryo development.

Climate Change- Concept

JoVE 10609

The certainty of climate change remains a public controversy despite the consensus among approximately 97% of active climate researchers, who not only agree that the Earth’s climate is changing but also state that this change is intensified by human activity, predominantly carbon emissions 1. The disconnect between the public and the experts is partly due to poor understanding of the…

 Lab Bio

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

Chromosomal Theory of Inheritance

JoVE 11010

In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of physical characteristics. The significance of his findings was not immediately recognized. In fact, the existence of genes was unknown at the time. Mendel referred to hereditary units as “factors.”

The mechanisms underlying Mendel’s observations—the basis of his laws of segregation and independent assortment—remained elusive. In the late 1800s, advances in microscopy and staining techniques allowed scientists to visualize mitosis and meiosis for the first time. In the early 1900s, Theodor Boveri, Walter Sutton, and others independently proposed that chromosomes may underlie Mendel’s laws—the chromosomal theory of inheritance. Researching sea urchins and grasshoppers, respectively, Boveri and Sutton noted striking similarities between chromosomes during meiosis and Mendel’s factors. Like Mendel’s factors, chromosomes come in pairs. Reminiscent of Mendel’s law of segregation, these pairs become separated during meiosis such that every gamete (e.g., sperm or egg) receives one chromosome from each pair. Chromosome pairs are segregated independently of one another, corresponding to Mendel’s law of independent assortment. The first c

 Core: Biology

Keystone Species

JoVE 10992

Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ecological community’s structure. Many factors affect community structure, including abiotic factors (e.g., sunlight and nutrients), disturbances (e.g., fire or flood), species interactions (e.g., predation or competition), and chance events (e.g., foreign species invasion). Certain species—such as keystone species—also play a pivotal role in the structure of a community. Relative to their abundance, keystone species have a disproportionately large impact on community structure. Keystone species exert top-down control over lower trophic level organisms and reduce those organisms’ exploitation of the ecosystem’s resources. The intertidal sea star (Pisaster ochraceus) is a keystone species that influences the biodiversity of the Pacific coast’s kelp forest ecosystem. If the sea star is removed, the population of their prey species (mussels) increases. Left unchecked, mussels overrun the community and displace other organisms—changing the community’s species composition and reducing biodiversity. Recognizing keystone species is important for the maintenance and restoration of ecosystems. The North American gray wolf is a keystone species that affects the biod

 Core: Biology


JoVE 10910

Neurulation is the embryological process which forms the precursors of the central nervous system and occurs after gastrulation has established the three primary cell layers of the embryo: ectoderm, mesoderm, and endoderm. In humans, the majority of this system is formed via primary neurulation, in which the central portion of the ectoderm—originally appearing as a flat sheet of cells—folds upwards and inwards, sealing off to form a hollow neural tube. As development proceeds, the anterior portion of the neural tube will give rise to the brain, with the rest forming the spinal cord. The central portion of the ectoderm that bends to generate the neural tube is aptly called the neural ectoderm, while the areas that flank it—along the periphery of the embryo—are the surface ectoderm. However, at the junction of the neural and surface ectoderm lies another population of cells, called the neural crest. As the neural folds (the edges of the elevating neural tube) begin to appear, neural crest cells (NCCs) can be visualized in their tips through the expression of characteristic markers, like the Pax7 transcription factor. As development proceeds and the neural folds fuse, NCCs can be observed either in the top-most portion of the neural tube or migrating along this structure’s sides towards lower regions of the embryo. To migrate, N

 Core: Biology


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

An Introduction to Cell Division

JoVE 5640

Cell division is the process by which a parent cell divides and gives rise to two or more daughter cells. It is a means of reproduction for single-cell organisms. In multicellular organisms, cell division contributes to growth, development, repair, and the generation of reproductive cells (sperms and eggs). Cell division is a tightly regulated process, and aberrant cell…

 Cell Biology

A Protocol for Bioinspired Design: A Ground Sampler Based on Sea Urchin Jaws

1Materials Science and Engineering Program, University of California, San Diego, 2Department of Mechanical and Aerospace Engineering, University of California, San Diego, 3Integrative Oceanography Division, Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, 4Marine Biology Research Division, Scripps Institution of Oceanography

JoVE 53554


Expression of Fluorescent Proteins in Branchiostoma lanceolatum by mRNA Injection into Unfertilized Oocytes

1Département de Biologie du Développement et Cellules Souches, Institut Pasteur, 2Laboratoire de Biologie du Développement de Villefranche-sur-Mer (UMR7009 CNRS/UPMC Univ Paris 06), Sorbonne Universités, 3Equipe Epigenetic Control of Normal and Pathological Hematopoiesis, Centre de Recherche en Cancérologie de Marseille, 4Unité de Dynamique des Interactions Membranaires Normales et Pathologiques, CNRS UMR5235/DAA/cc107/Université Montpellier II, 5Plateforme BioEmergences IBiSA FBI, CNRS-NED, Institut de Neurobiologie Alfred Fessard

JoVE 52042

 Developmental Biology
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