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Ricin (/ ˈ r aɪ s ɪ n / RY-sin) is a lectin (a carbohydrate-binding protein) and a highly potent toxin produced in the seeds of the castor oil plant, Ricinus communis.The median lethal dose (LD 50) of ricin for mice is around 22 micrograms per kilogram of body weight via intraperitoneal injection.
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthesis) serve as enzyme substrates, with conversion by the living organism either into simpler or more complex ...
Ecopsychology is an interdisciplinary and transdisciplinary field that focuses on the synthesis of ecology and psychology and the promotion of sustainability. [1] [2] [3] It is distinguished from conventional psychology as it focuses on studying the emotional bond between humans and the Earth.
Land, unlike the ocean, is not continuous; there are important geographical barriers to free movement. The nature of the substrate, although important in water is especially vital in terrestrial environment. Soil, not air, is the source of highly variable nutrients; it is a highly developed ecological subsystem.
The rhizosphere is the thin area of soil immediately surrounding the root system. It is a densely populated area in which the roots compete with invading root systems of neighboring plant species for space, water, and mineral nutrients as well as form positive and negative relationships with soil-borne microorganisms such as bacteria, fungi and insects.
It can often be difficult in practice to distinguish allelopathy from resource competition. While the former is caused by the addition of a harmful chemical agent to the environment, the latter is caused by the removal of essential resources (nutrients, light, water, etc.). Often, both mechanisms can act simultaneously.
Since ricin is a protein, antibodies may be produced by inoculation, allowing resistance of up to 800 times a normal lethal dose. Ricin has been used in assassinations, a notorious case being the use of a 1.53 mm pellet holding a few hundred millionths of a gram of ricin to kill the Bulgarian broadcaster, Georgi Markov , who died 4 days after ...
Osmoprotectants are also important for the maintenance of top soil bacteria populations. Desiccation of top soils results in increased salinity. In these situations, the soil microbes increase the concentration of these molecule in their cytoplasm into the molar range allowing them to persist until conditions approve. [ 2 ]