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October, 2006
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Malpighian Tubules: Slender tubular or hairlike excretory structures found in insects. They emerge from the alimentary canal between the mesenteron (midgut) and the proctodeum (hindgut).

Osmoregulation in Insects

JoVE 10990

Malpighian tubules are specialized structures found in the digestive systems of many arthropods, including most insects, which handle excretion and osmoregulation. The tubules are typically arranged in pairs and have a convoluted structure that increases their surface area.

Malpighian tubules extend from the digestive tract, typically the area between the midgut and hindgut, into the hemolymph—a mixture of blood and interstitial fluid found in insects and other arthropods, as well as most mollusks. Unlike other excretory systems, the excretory processes of Malpighian tubules lack a filtration step. Metabolic wastes, like uric acid, diffuse into the tubules from the hemolymph. The tubules are lined with a layer of transport epithelia. These specialized epithelial cells contain pumps that actively transport ions, like sodium (Na+) and potassium (K+), from the hemolymph into the interior of the tubule, called the lumen. Osmosis allows water to follow ions into the tubules passively. From the tubule lumen, water, ions, and waste travel from the intestine to the rectum. Tiny, protruding microvilli lining the inside of the tubules help maximize solute-water coupling and the propulsion of uric acid crystals through the tubules. In the rectum, specialized glands pump many of the ions back into the hemolymph. Osmosis

 Core: Regulation and Excretion

What Are Osmoregulation and Excretion?

JoVE 11001

Organisms must keep bodily fluids at a constant temperature and pH while maintaining specific solute concentrations in order to support life functions. Osmoregulation is the process that balances solute and water levels.

Osmosis is the tendency of water to move from solutions with lower ion concentrations, or osmolarities, to those with higher ion concentrations. Osmosis occurs in response to differences in the molecular concentrations of solutions separated by a semipermeable membrane. Bodily fluids, which are separated by such membranes, contain water, non-electrolytes, and electrolytes—solutes that dissolve into ions in water. Both electrolytes and non-electrolytes influence osmotic balance. However, since the more important factor to osmosis is solute number, rather than size, the contribution of electrolytes is more significant. Unlike water, electrolytes cannot diffuse passively through membranes but rely on facilitated diffusion and active transport. In facilitated diffusion, protein-based channels move solutes across membranes. Conversely, energy is used to move ions against concentration gradients in active transport. When animals ingest food, material that cannot be used is excreted from the body. Excretory systems in nature involve tradeoffs between conserving energy and water. Nitrogen is among the most significant

 Core: Regulation and Excretion

Protocols for Investigating the Host-tissue Distribution, Transmission-mode, and Effect on the Host Fitness of a Densovirus in the Cotton Bollworm

1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, 2Tobacco Research Institute, Chinese Academy of Agricultural Sciences, 3Crop and Environment Sciences, Harper Adams University

JoVE 55534

 Immunology and Infection

Disclosing Hemolymph Collection and Inoculation of Metarhizium Blastospores into Rhipicephalus Microplus Ticks Towards Invertebrate Pathology Studies

1Post-Graduate Program in Veterinary Sciences, Federal Rural University of Rio de Janeiro, 2Department of Animal Parasitology, Federal Rural University of Rio de Janeiro, 3Department of Epidemiology and Public Health, Federal Rural University of Rio de Janeiro

JoVE 59899

 Immunology and Infection

Fat Body Organ Culture System in Aedes Aegypti, a Vector of Zika Virus

1Department of Biology, New Mexico State University, 2Department of Molecular Genetics and Microbiology, Duke University, 3Department of Computer Sciences, New Mexico State University, 4Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 5Institute of Applied Biosciences, New Mexico State University

JoVE 55508


Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

1Microbiology and Pathogenesis Activity, Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 2Tick-Borne Diseases Activity, Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention

JoVE 3894

 Immunology and Infection
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