Search Results

The Ebola virus comprises a group of pathogenic agents that cause severe and deadly hemorrhagic fevers in humans and other primates. During 2014 and 2015, an Ebola virus epidemic in West Africa—predominantly, the countries of Guinea, Liberia, and…

A family of adenosine triphosphate–binding cassette (ABC) transmembrane proteins that use energy to transport various molecules across extracellular and intracellular membranes (cytoplasmic membranes, endoplasmic reticulum, mitochondria, or…

One of the major plant hormones that plays an important role in plant growth and development. Abscisic acid (ABA) is ubiquitous in vascular plants; the highest levels are found in young leaves and in developing fruits and seeds. Abscisic acid is…

The net movement (transport) of water and solutes from outside an organism to its interior. The unidirectional flow of materials into an animal from the environment generally takes place across the alimentary tract, the lungs, or the skin, and in…

A naturally occurring quaternary ammonium cation ester, with the formula CH3(O)COC2H4N(CH3)3+, which plays a prominent role in nervous system function as a neurotransmitter. Acetylcholine (Fig. 1) is an organic compound released from certain…

An order of monocotyledonous angiosperms composed of a single genus, Acorus (sweet flag or sweet calamus), with two species widespread in the Northern Hemisphere. Formerly, Acorus was included in the aroid family, Araceae, but several lines of…

A viral disease of humans caused by the human immunodeficiency virus (HIV), which attacks and compromises the body's immune system. Individuals infected with the human immunodeficiency virus (HIV) proceed through a spectrum of stages that ultimately…