#Science_News #Science #Organism #endosymbiont #Biology
An endosymbiont or endobiont is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον endon "within", σύν syn "together" and βίωσις biosis "living".) Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes, single-cell algae inside reef-building corals and bacterial endosymbionts that provide essential nutrients to insects.
The history behind the concept of endosymbiosis stems from the postulates of the endosymbiotic theory. The endosymbiotic theory (symbiogenesis) pushes the notion of bacteria exclusively living in eukaryotic organisms after being engulfed by them. This is popular with the concept of organelle development observed with eukaryotes. Two major types of organelle in eukaryotic cells, mitochondria and plastids such as chloroplasts, are considered to be bacterial endosymbionts.
There are two types of symbiont transmissions. In horizontal transmission, each new generation acquires free living symbionts from the environment. An example is the nitrogen-fixing bacteria in certain plant roots. Vertical transmission takes place when the symbiont is transferred directly from parent to offspring. It is also possible for both to be involved in a mixed-mode transmission, where symbionts are transferred vertically for some generation before a switch of host occurs and new symbionts are horizontally acquired from the environment.
In vertical transmissions, the symbionts often have a reduced genome and are no longer able to survive on their own. As a result, the symbiont depends on the host, resulting in a highly intimate co-dependent relationship. For instance, pea aphid symbionts have lost genes for essential molecules, now relying on the host to supply them with nutrients. In return, the symbionts synthesize essential amino acids for the aphid host. Other examples include Wigglesworthia nutritional symbionts of tse-tse flies, or in sponges. When a symbiont reaches this stage, it begins to resemble a cellular organelle, similar to mitochondria or chloroplasts.
Many instances of endosymbiosis are obligate; that is, either the endosymbiont or the host cannot survive without the other, such as the gutless marine worms of the genus Riftia, which get nutrition from their endosymbiotic bacteria. The most common examples of obligate endosymbioses are mitochondria and chloroplasts. Some human parasites, e.g. Wuchereria bancrofti and Mansonella perstans, thrive in their intermediate insect hosts because of an obligate endosymbiosis with Wolbachia spp. They can both be eliminated from hosts by treatments that target this bacterium. However, not all endosymbioses are obligate and some endosymbioses can be harmful to either of the organisms involved.
An endosymbiont or endobiont is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον endon "within", σύν syn "together" and βίωσις biosis "living".) Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes, single-cell algae inside reef-building corals and bacterial endosymbionts that provide essential nutrients to insects.
The history behind the concept of endosymbiosis stems from the postulates of the endosymbiotic theory. The endosymbiotic theory (symbiogenesis) pushes the notion of bacteria exclusively living in eukaryotic organisms after being engulfed by them. This is popular with the concept of organelle development observed with eukaryotes. Two major types of organelle in eukaryotic cells, mitochondria and plastids such as chloroplasts, are considered to be bacterial endosymbionts.
There are two types of symbiont transmissions. In horizontal transmission, each new generation acquires free living symbionts from the environment. An example is the nitrogen-fixing bacteria in certain plant roots. Vertical transmission takes place when the symbiont is transferred directly from parent to offspring. It is also possible for both to be involved in a mixed-mode transmission, where symbionts are transferred vertically for some generation before a switch of host occurs and new symbionts are horizontally acquired from the environment.
In vertical transmissions, the symbionts often have a reduced genome and are no longer able to survive on their own. As a result, the symbiont depends on the host, resulting in a highly intimate co-dependent relationship. For instance, pea aphid symbionts have lost genes for essential molecules, now relying on the host to supply them with nutrients. In return, the symbionts synthesize essential amino acids for the aphid host. Other examples include Wigglesworthia nutritional symbionts of tse-tse flies, or in sponges. When a symbiont reaches this stage, it begins to resemble a cellular organelle, similar to mitochondria or chloroplasts.
Many instances of endosymbiosis are obligate; that is, either the endosymbiont or the host cannot survive without the other, such as the gutless marine worms of the genus Riftia, which get nutrition from their endosymbiotic bacteria. The most common examples of obligate endosymbioses are mitochondria and chloroplasts. Some human parasites, e.g. Wuchereria bancrofti and Mansonella perstans, thrive in their intermediate insect hosts because of an obligate endosymbiosis with Wolbachia spp. They can both be eliminated from hosts by treatments that target this bacterium. However, not all endosymbioses are obligate and some endosymbioses can be harmful to either of the organisms involved.
#Science_News #Science #Organism #endosymbiont #Biology
An endosymbiont or endobiont is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον endon "within", σύν syn "together" and βίωσις biosis "living".) Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes, single-cell algae inside reef-building corals and bacterial endosymbionts that provide essential nutrients to insects.
The history behind the concept of endosymbiosis stems from the postulates of the endosymbiotic theory. The endosymbiotic theory (symbiogenesis) pushes the notion of bacteria exclusively living in eukaryotic organisms after being engulfed by them. This is popular with the concept of organelle development observed with eukaryotes. Two major types of organelle in eukaryotic cells, mitochondria and plastids such as chloroplasts, are considered to be bacterial endosymbionts.
There are two types of symbiont transmissions. In horizontal transmission, each new generation acquires free living symbionts from the environment. An example is the nitrogen-fixing bacteria in certain plant roots. Vertical transmission takes place when the symbiont is transferred directly from parent to offspring. It is also possible for both to be involved in a mixed-mode transmission, where symbionts are transferred vertically for some generation before a switch of host occurs and new symbionts are horizontally acquired from the environment.
In vertical transmissions, the symbionts often have a reduced genome and are no longer able to survive on their own. As a result, the symbiont depends on the host, resulting in a highly intimate co-dependent relationship. For instance, pea aphid symbionts have lost genes for essential molecules, now relying on the host to supply them with nutrients. In return, the symbionts synthesize essential amino acids for the aphid host. Other examples include Wigglesworthia nutritional symbionts of tse-tse flies, or in sponges. When a symbiont reaches this stage, it begins to resemble a cellular organelle, similar to mitochondria or chloroplasts.
Many instances of endosymbiosis are obligate; that is, either the endosymbiont or the host cannot survive without the other, such as the gutless marine worms of the genus Riftia, which get nutrition from their endosymbiotic bacteria. The most common examples of obligate endosymbioses are mitochondria and chloroplasts. Some human parasites, e.g. Wuchereria bancrofti and Mansonella perstans, thrive in their intermediate insect hosts because of an obligate endosymbiosis with Wolbachia spp. They can both be eliminated from hosts by treatments that target this bacterium. However, not all endosymbioses are obligate and some endosymbioses can be harmful to either of the organisms involved.
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