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October, 2006
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Body Size: The physical measurements of a body.

Types of Selection

JoVE 10959

Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural selection can be directional, stabilizing, or disruptive. Directional selection favors one extreme trait and shifts the population towards that phenotype while selecting against individuals displaying alternate traits. Stabilizing selection favors an intermediate trait with a narrow range of variation. Deviation from the optimal phenotype towards an extreme one is unfavorable. Finally, disruptive selection favors both extremes of a phenotype, while intermediate phenotypes are selected against. Directional selection favors one extreme of a phenotype. For example, in sockeye salmon, research has shown that directional selection is favoring seasonally earlier migration. This is thought to be due to predation pressure from fisheries, as fishing increases later in the migration season. Thus, fish arriving and spawning earlier may have a better chance of reaching their destination to reproduce before being caught by fishermen. When a particular non-extreme phenotype is favored, this is referred to as stabilizing selection. For example, across many species of birds, clutch size (the number of eggs in a single brood) is kept within an optimal window. Lapwings and golden plovers typically lay four eggs. This optimiza

 Core: Biology

Evaluating the Heat Transfer of a Spin-and-Chill

JoVE 10440

Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA

The Spin-and-Chill uses heat transfer and fluid flow fundamentals to chill beverages from room temperature to 38 °F in as little as 2 min. It would take a refrigerator approximately 240 min and an ice chest…

 Chemical Engineering

Lung Capacity

JoVE 10883

The air in the lungs is measured in volumes and capacities. Lung volume measures reflect the amount of air taken in, released, or left over after a lung function, like a single inhalation. Lung capacity measures are sums of two or more lung volume measures.

There are four defined lung volume measures: tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Tidal volume is the amount of air inhaled and exhaled in a normal breath. Inspiratory (inhalation-related) reserve volume is the additional amount of air that can be inhaled after a regular inspiration. Expiratory (exhalation-related) reserve volume is the amount of air that can be exhaled after normal exhalation. Residual volume is the amount of air remaining in the lungs after forced exhalation (i.e., blowing). There are four defined lung capacity measures: inspiratory capacity, functional residual capacity, vital capacity, and total lung capacity. Inspiratory capacity is the volume of air that can be inhaled after normal exhalation. It is the sum of the two volume measures involving inhalation: tidal volume and inspiratory reserve volume. Functional residual capacity is the volume of air remaining in the lungs after normal exhalation and is equal to the sum of the expiratory reserve and residual volumes. Vital capacity is the maximum volume of air t

 Core: Biology

Trophic Efficiency

JoVE 10930

Trophic level transfer efficiency (TLTE) is a measure of the total energy transfer from one trophic level to the next. Due to extensive energy loss as metabolic heat, an average of only 10% of the original energy obtained is passed on to the next level. This pattern of energy loss severely limits the possible number of trophic levels in a food chain.

Following the second law of thermodynamics, large amounts of energy are lost from the ecosystem and from one trophic level to the next as it is transferred and transformed. In biological systems, this energy is lost as metabolic heat during respiration as one organism consumes the next. The measurement of energy transfer from one trophic level to the next is known as trophic level transfer efficiency (TLTE) and is a function of energy production of the present trophic level and that at the previous level. This measurement has broad implications concerning the total length of food chains. In general, only about 10% of energy is transferred from one trophic level to the next, and this number can vary from 5-20% depending on the ecosystem. This means that 90% of obtained energy is lost at each trophic level, greatly affecting the maximum number of possible levels in the ecosystem. For example, if an ecosystem received 600,000 Kcal of solar energy from the sun, primary producers would pass on only 60,000 K

 Core: Biology

Using Deuterium Oxide as a Non-Invasive, Non-Lethal Tool for Assessing Body Composition and Water Consumption in Mammals

1Department of Veterinary Pathobiology, University of Missouri, 2College of Veterinary Medicine, University of Missouri, 3Department of Animal Science, University of Missouri, 4School of Natural Resources, University of Missouri, 5USDA USFS Northern Research Station

JoVE 59442


Large-Scale Production of Cardiomyocytes from Human Pluripotent Stem Cells Using a Highly Reproducible Small Molecule-Based Differentiation Protocol

1Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, 2Developmental and Stem Cell Biology Division, Victor Chang Cardiac Research Institute, 3St. Vincent´s Clinical School, Faculty of Medicine, University of New South Wales, 4School of Biotechnology and Biomolecular Sciences, University of New South Wales, 5Department of Developmental Biology, University of Science and Culture, 6Heart Centre for Children, The Children´s Hospital at Westmead, 7Sydney Medical School, University of Sydney, 8Department of Developmental Biology, University of Science and Culture, Tehran, Iran

JoVE 54276

 Developmental Biology

Contextual and Cued Fear Conditioning Test Using a Video Analyzing System in Mice

1Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 2Japan Science and Technology Agency, Core Research for Evolutionary Science and Technology (CREST), 3Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences

JoVE 50871


Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

1Faculty of Environmental Sciences, Czech University of Life Sciences Prague, 2T. G. Masaryk Water Research Institute, 3Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague

JoVE 57446


Adapting Human Videofluoroscopic Swallow Study Methods to Detect and Characterize Dysphagia in Murine Disease Models

1Department of Otolaryngology - Head and Neck Surgery, University of Missouri, 2Department of Communication Science and Disorders, University of Missouri, 3Department of Medicine, University of Missouri

JoVE 52319


Efficient Gene Delivery into Multiple CNS Territories Using In Utero Electroporation

1Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, University of Calgary, 2Department of Medical Genetics, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary

JoVE 2957


Invasive Hemodynamic Assessment for the Right Ventricular System and Hypoxia-Induced Pulmonary Arterial Hypertension in Mice

1Beijing Key Laboratory of Pre-clinical Research and Evaluation for Cardiovascular Implant Materials, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Centre for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 2Laboratory Animal Center, Peking University, 3Center of Cardiac Surgery for Adults, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Centre for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College

JoVE 60090


Using Optical Coherence Tomography and Optokinetic Response As Structural and Functional Visual System Readouts in Mice and Rats

1Department of Neurology, Heinrich-Heine-University Düsseldorf, 2Department of Cell Physiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, 3Division of Neuroinflammation and Glial Biology, Department of Neurology, University of California San Francisco

JoVE 58571


Transdermal Measurement of Glomerular Filtration Rate in Mice

1Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, 2Department of Cellular and Molecular Physiology, University of Liverpool, 3MediBeacon GmbH, 4Department of Veterinary Pathology and Public Health, Institute of Veterinary Science, University of Liverpool

JoVE 58520

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