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Etoposide was first synthesized in 1966 and U.S. Food and Drug Administration approval was granted in 1983. [ 6 ] The nickname VP-16 likely comes from a compounding of the last name of one of the chemists who performed early work on the drug (von Wartburg) and podophyllotoxin. [ 12 ]
Etoposide, a semi-synthetic derivative of epipodophyllotoxin is commonly used to study this apoptotic mechanism and include: Etoposide; Teniposide; Both etoposide and teniposide are naturally occurring semi-synthetic derivatives of podophyllotoxins and are important anti-cancer drugs that function to inhibit TopII activity. [67]
A balance in these transfers is vital to the health and stability of an ecosystem. [4] Consumers balance the food chain in an ecosystem by keeping plant populations at a reasonable number. Without proper balance, an ecosystem can collapse and cause the decline of all affected species.
The black walnut secretes a chemical from its roots that harms neighboring plants, an example of competitive antagonism.. In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other.
Type II topoisomerases increase or decrease the linking number of a DNA loop by 2 units, and it promotes chromosome disentanglement. For example, DNA gyrase, a type II topoisomerase observed in E. coli and most other prokaryotes, introduces negative supercoils and decreases the linking number by 2.
Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce the abundance, or alter the behavior of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate ...
This occurs by a mechanism similar to steroid synthesis in vertebrates. Ecdysone and 20-hydroxyecdysone regulate larval molts, onset of puparium formation, and metamorphosis. As these hormones are hydrophobic, they traverse lipid membranes and permeate the tissues of an organism. Indeed, the ecdysone receptor is an intracellular protein.
Ecosystem services are ecologically mediated functional processes essential to sustaining healthy human societies. [6] Water provision and filtration, production of biomass in forestry, agriculture, and fisheries, and removal of greenhouse gases such as carbon dioxide (CO 2) from the atmosphere are examples of ecosystem services essential to public health and economic opportunity.