Planaria - Revision history

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2023-05-10T18:07:59Z

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← Older revision		Revision as of 14:07, 10 May 2023
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	== Introduction ==		== Introduction ==
	Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.		Planaria, or [[flatworms]], which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.
	[[File:Image203 (2).jpg\|right\|300px\|thumb\|S. mediterranea midsection cut regeneration group]]		[[File:Image203 (2).jpg\|right\|300px\|thumb\|S. mediterranea midsection cut regeneration group]]

Ephanrah at 19:41, 5 May 2021

2021-05-05T19:41:30Z

← Older revision		Revision as of 15:41, 5 May 2021
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	Over a third of the world’s population is estimated to be infected with parasitic worms" [4]. Most cases of parasitic flatworm infections are associated with unsanitary drinking water, as these organisms are typically found near the bottom of freshwater sources. Symptoms of host infection result from egg deposition within the liver, gastrointestinal tract, or urinary bladder, resulting in granuloma formation and fibrosis [4]. Drugs such as Praziquantel (PZQ), an anthelmintic, can cure fluke infection by disrupting the neoblast regeneration pattern in planarians. Specifically, the drug causes increased levels of calcium which is suspected to be the main inhibitor of proper neoblast regeneration [5]. This disruption leads to regeneration of Planaria with two heads by inhibiting posterior expression, eventually driving them out of the host.		Over a third of the world’s population is estimated to be infected with parasitic worms" [4]. Most cases of parasitic flatworm infections are associated with unsanitary drinking water, as these organisms are typically found near the bottom of freshwater sources. Symptoms of host infection result from egg deposition within the liver, gastrointestinal tract, or urinary bladder, resulting in granuloma formation and fibrosis [4]. Drugs such as Praziquantel (PZQ), an anthelmintic, can cure fluke infection by disrupting the neoblast regeneration pattern in planarians. Specifically, the drug causes increased levels of calcium which is suspected to be the main inhibitor of proper neoblast regeneration [5]. This disruption leads to regeneration of Planaria with two heads by inhibiting posterior expression, eventually driving them out of the host.
	== Stem Cells and Regeneration ==		== Stem Cells and Regeneration ==
			[[File:Image212_(2).jpg\|right\|300px\|thumb\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]
	Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].		Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].
	~~[[File:Image212_(2).jpg\|right\|300px\|thumb\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]~~

	== References ==		== References ==

Ephanrah at 19:36, 5 May 2021

2021-05-05T19:36:58Z

← Older revision		Revision as of 15:36, 5 May 2021
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	==Anatomy==		==Anatomy==
			[[File:EVS463_Planarian_Anatomy_1.JPG \|left\|300px\|thumb\|Anatomy of Planarian gut, neurons, axons, and pharynx [9]]]
	Planarians are triploblastic, involving all three germ layers (ecto-, meso-. and endoderm) and an organized nervous system composed of two anterior cephalic ganglia and two parallel nerve chords that run ventrally along the length of the body [9]. They also contain two photoreceptors which are connected to the nervous system by axons of the optic chiasm [9]. In addition, planarians contain chemoreceptors and rheoreceptors at the anterior end which send projections to the cephalic ganglia [1]. Movement is permitted through the use of motile cilia on the ventral epithelium [9]. These organisms lack a coelom, and all space between the organs and nervous system is composed of mesenchyme [1]. The body wall contains a complex of longitudinal, diagonal, and circular muscle fibers which aid in negotiating obstacles [1]. Food is ingested through an extensible pharynx, which serves as both the mouth and anus, connected to a three-branch (triclad) digestive system [1].		Planarians are triploblastic, involving all three germ layers (ecto-, meso-. and endoderm) and an organized nervous system composed of two anterior cephalic ganglia and two parallel nerve chords that run ventrally along the length of the body [9]. They also contain two photoreceptors which are connected to the nervous system by axons of the optic chiasm [9]. In addition, planarians contain chemoreceptors and rheoreceptors at the anterior end which send projections to the cephalic ganglia [1]. Movement is permitted through the use of motile cilia on the ventral epithelium [9]. These organisms lack a coelom, and all space between the organs and nervous system is composed of mesenchyme [1]. The body wall contains a complex of longitudinal, diagonal, and circular muscle fibers which aid in negotiating obstacles [1]. Food is ingested through an extensible pharynx, which serves as both the mouth and anus, connected to a three-branch (triclad) digestive system [1].

Ephanrah at 19:29, 5 May 2021

2021-05-05T19:29:28Z

← Older revision		Revision as of 15:29, 5 May 2021
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	==Anatomy==		==Anatomy==
	Planarians are triploblastic, involving all three germ layers (ecto-, meso-. and endoderm) and an organized nervous system composed of two anterior cephalic ganglia and two parallel nerve chords that run ventrally along the length of the body [9]. They also contain two photoreceptors which are connected to the nervous system by axons of the optic chiasm [9]. Movement is permitted through the use of motile cilia on the ventral~~-most~~ epithelium [9]. ~~Interestingly~~, ~~these organisms contain stem cells known~~ as ~~neoblasts allowing regeneration following injury making them~~ a ~~great model organism for scientific study~~ [1].		Planarians are triploblastic, involving all three germ layers (ecto-, meso-. and endoderm) and an organized nervous system composed of two anterior cephalic ganglia and two parallel nerve chords that run ventrally along the length of the body [9]. They also contain two photoreceptors which are connected to the nervous system by axons of the optic chiasm [9]. In addition, planarians contain chemoreceptors and rheoreceptors at the anterior end which send projections to the cephalic ganglia [1]. Movement is permitted through the use of motile cilia on the ventral epithelium [9]. These organisms lack a coelom, and all space between the organs and nervous system is composed of mesenchyme [1]. The body wall contains a complex of longitudinal, diagonal, and circular muscle fibers which aid in negotiating obstacles [1]. Food is ingested through an extensible pharynx, which serves as both the mouth and anus, connected to a three-branch (triclad) digestive system [1].


	==Planarian Diversity and Distribution ==		==Planarian Diversity and Distribution ==

Ephanrah: Addition of Anatomy section

2021-05-05T19:13:24Z

Addition of Anatomy section

← Older revision		Revision as of 15:13, 5 May 2021
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	Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.		Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.
	[[File:Image203 (2).jpg\|right\|300px\|thumb\|S. mediterranea midsection cut regeneration group]]		[[File:Image203 (2).jpg\|right\|300px\|thumb\|S. mediterranea midsection cut regeneration group]]

			==Anatomy==
			Planarians are triploblastic, involving all three germ layers (ecto-, meso-. and endoderm) and an organized nervous system composed of two anterior cephalic ganglia and two parallel nerve chords that run ventrally along the length of the body [9]. They also contain two photoreceptors which are connected to the nervous system by axons of the optic chiasm [9]. Movement is permitted through the use of motile cilia on the ventral-most epithelium [9]. Interestingly, these organisms contain stem cells known as neoblasts allowing regeneration following injury making them a great model organism for scientific study [1].

	==Planarian Diversity and Distribution ==		==Planarian Diversity and Distribution ==
	Within the [[Tricladida]] exist three proposed taxonomic groups, which are based on their different habitats: [[Paludicola]] (freshwater planarians), [[Terricola]] (land planarians), and [[Maricola]] (marine planarians) [8]. These three taxonomic groups may be even further subdivided by classification of anatomical and external feature differences. "Molecular sequence data has helped to clarify the phylogenetic relationships and the evolutionary history of the Tricladida and in many cases facilitated a more natural classification. However, at certain levels resolution is still poor, thus requiring further studies" [8]. The genome of planarians is vast due to their ancient age and evolutionary processes making a difficult challenge to truly understand the depth of [[diversity]] between the proposed groups.		Within the [[Tricladida]] exist three proposed taxonomic groups, which are based on their different habitats: [[Paludicola]] (freshwater planarians), [[Terricola]] (land planarians), and [[Maricola]] (marine planarians) [8]. These three taxonomic groups may be even further subdivided by classification of anatomical and external feature differences. "Molecular sequence data has helped to clarify the phylogenetic relationships and the evolutionary history of the Tricladida and in many cases facilitated a more natural classification. However, at certain levels resolution is still poor, thus requiring further studies" [8]. The genome of planarians is vast due to their ancient age and evolutionary processes making a difficult challenge to truly understand the depth of [[diversity]] between the proposed groups.
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	#Alvarado, Alejandro Sánchez. “Planarians.” Current Biology, vol. 14, no. 18, Elsevier Inc, 2004, pp. R737–R738, doi:10.1016/j.cub.2004.09.005.		#Alvarado, Alejandro Sánchez. “Planarians.” Current Biology, vol. 14, no. 18, Elsevier Inc, 2004, pp. R737–R738, doi:10.1016/j.cub.2004.09.005.
	#Rink, Jochen C. Planarian Regeneration Methods and Protocols / Edited by Jochen C. Rink. 1st ed. 2018., Springer New York, 2018, doi:10.1007/978-1-4939-7802-1.		#Rink, Jochen C. Planarian Regeneration Methods and Protocols / Edited by Jochen C. Rink. 1st ed. 2018., Springer New York, 2018, doi:10.1007/978-1-4939-7802-1.
			#Elliott, Sarah A., and Alejandro Sánchez Alvarado. “The History and Enduring Contributions of Planarians to the Study of Animal Regeneration.” Wiley Interdisciplinary Reviews. Developmental Biology, vol. 2, no. 3, John Wiley & Sons, Inc, 2013, pp. 301–26, doi:10.1002/wdev.82.
	<!--Looks really great Ethan, I really enjoyed how in depth you went especially regarding the stem cell stuff, super interesting. Only recommendation I would have would possibly include a diagram of their anatomy so it would be easier to see what they look like-->		<!--Looks really great Ethan, I really enjoyed how in depth you went especially regarding the stem cell stuff, super interesting. Only recommendation I would have would possibly include a diagram of their anatomy so it would be easier to see what they look like-->

Ephanrah at 19:53, 2 May 2021

2021-05-02T19:53:43Z

← Older revision		Revision as of 15:53, 2 May 2021
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	== Introduction ==		== Introduction ==
	Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.		Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.
	[[File:Image203 (2).jpg\|right\|300px\|S. mediterranea ~~control~~ regeneration group]]		[[File:Image203 (2).jpg\|right\|300px\|thumb\|S. mediterranea midsection cut regeneration group]]
	==Planarian Diversity and Distribution ==		==Planarian Diversity and Distribution ==
	Within the [[Tricladida]] exist three proposed taxonomic groups, which are based on their different habitats: [[Paludicola]] (freshwater planarians), [[Terricola]] (land planarians), and [[Maricola]] (marine planarians) [8]. These three taxonomic groups may be even further subdivided by classification of anatomical and external feature differences. "Molecular sequence data has helped to clarify the phylogenetic relationships and the evolutionary history of the Tricladida and in many cases facilitated a more natural classification. However, at certain levels resolution is still poor, thus requiring further studies" [8]. The genome of planarians is vast due to their ancient age and evolutionary processes making a difficult challenge to truly understand the depth of [[diversity]] between the proposed groups.		Within the [[Tricladida]] exist three proposed taxonomic groups, which are based on their different habitats: [[Paludicola]] (freshwater planarians), [[Terricola]] (land planarians), and [[Maricola]] (marine planarians) [8]. These three taxonomic groups may be even further subdivided by classification of anatomical and external feature differences. "Molecular sequence data has helped to clarify the phylogenetic relationships and the evolutionary history of the Tricladida and in many cases facilitated a more natural classification. However, at certain levels resolution is still poor, thus requiring further studies" [8]. The genome of planarians is vast due to their ancient age and evolutionary processes making a difficult challenge to truly understand the depth of [[diversity]] between the proposed groups.
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	== Stem Cells and Regeneration ==		== Stem Cells and Regeneration ==
	Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].		Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].
	[[File:Image212_(2).jpg\|right\|300px\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]		[[File:Image212_(2).jpg\|right\|300px\|thumb\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]

	== References ==		== References ==

Njhenshu: The LinkTitles extension automatically added links to existing pages (https://github.com/bovender/LinkTitles).

2021-04-29T17:05:10Z

← Older revision		Revision as of 13:05, 29 April 2021
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	== Introduction ==		== Introduction ==
	Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex organisms are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.		Planaria, or flatworms, which occupy the order [[Tricladida]] within the phylum [[Platyhelminthes]], are commonly inhabitants of freshwater sources such as streams or ponds, but some are terrestrial in deep soils [1]. These complex [[organisms]] are known to be scavengers, predators, and in many cases parasitic. Planarians such as ''Schmidtea mediterranea'' are known for their remarkable ability to regenerate from pluripotent stem cells scattered throughout their bodies [2]. These adult stem cells, also known as neoblasts, allow planarians to reproduce asexually as well as simply regenerating their entire body from a fragment roughly 1/279 the size of the original worm [7]. These model organisms are medically and scientifically important, as understanding the process of regeneration may carry incredible value to advanced technologies.
	[[File:Image203 (2).jpg\|right\|300px\|S. mediterranea control regeneration group]]		[[File:Image203 (2).jpg\|right\|300px\|S. mediterranea control regeneration group]]
	==Planarian Diversity and Distribution ==		==Planarian Diversity and Distribution ==
	Within the [[Tricladida]] exist three proposed taxonomic groups, which are based on their different habitats: [[Paludicola]] (freshwater planarians), [[Terricola]] (land planarians), and [[Maricola]] (marine planarians) [8]. These three taxonomic groups may be even further subdivided by classification of anatomical and external feature differences. "Molecular sequence data has helped to clarify the phylogenetic relationships and the evolutionary history of the Tricladida and in many cases facilitated a more natural classification. However, at certain levels resolution is still poor, thus requiring further studies" [8]. The genome of planarians is vast due to their ancient age and evolutionary processes making a difficult challenge to truly understand the depth of diversity between the proposed groups.		Within the [[Tricladida]] exist three proposed taxonomic groups, which are based on their different habitats: [[Paludicola]] (freshwater planarians), [[Terricola]] (land planarians), and [[Maricola]] (marine planarians) [8]. These three taxonomic groups may be even further subdivided by classification of anatomical and external feature differences. "Molecular sequence data has helped to clarify the phylogenetic relationships and the evolutionary history of the Tricladida and in many cases facilitated a more natural classification. However, at certain levels resolution is still poor, thus requiring further studies" [8]. The genome of planarians is vast due to their ancient age and evolutionary processes making a difficult challenge to truly understand the depth of [[diversity]] between the proposed groups.

	The distribution of planarians ranges from temperate to tropical and has been modified by introduction of species to newer continents. Climate and moisture play a large role in the distribution of these organisms as they are most vulnerable to desiccation. Terrestrial planarians are found scattered throughout temperate, tropical, and subtropical regions across the globe, whereas the majority of freshwater planarians are mainly confined to the temperate and tropical regions of North America, Europe, and Asia in which draught rarely occurs [8].		The distribution of planarians ranges from temperate to tropical and has been modified by introduction of species to newer continents. Climate and moisture play a large role in the distribution of these organisms as they are most vulnerable to desiccation. Terrestrial planarians are found scattered throughout temperate, tropical, and subtropical regions across the globe, whereas the majority of freshwater planarians are mainly confined to the temperate and tropical regions of North America, Europe, and Asia in which draught rarely occurs [8].

Nikolaih at 23:19, 13 April 2021

2021-04-13T23:19:22Z

← Older revision		Revision as of 19:19, 13 April 2021
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	#Alvarado, Alejandro Sánchez. “Planarians.” Current Biology, vol. 14, no. 18, Elsevier Inc, 2004, pp. R737–R738, doi:10.1016/j.cub.2004.09.005.		#Alvarado, Alejandro Sánchez. “Planarians.” Current Biology, vol. 14, no. 18, Elsevier Inc, 2004, pp. R737–R738, doi:10.1016/j.cub.2004.09.005.
	#Rink, Jochen C. Planarian Regeneration Methods and Protocols / Edited by Jochen C. Rink. 1st ed. 2018., Springer New York, 2018, doi:10.1007/978-1-4939-7802-1.		#Rink, Jochen C. Planarian Regeneration Methods and Protocols / Edited by Jochen C. Rink. 1st ed. 2018., Springer New York, 2018, doi:10.1007/978-1-4939-7802-1.

			<!--Looks really great Ethan, I really enjoyed how in depth you went especially regarding the stem cell stuff, super interesting. Only recommendation I would have would possibly include a diagram of their anatomy so it would be easier to see what they look like-->

Ephanrah: /* Stem Cells and Regeneration */

2021-04-12T23:49:37Z

Stem Cells and Regeneration

← Older revision		Revision as of 19:49, 12 April 2021
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	== Stem Cells and Regeneration ==		== Stem Cells and Regeneration ==
	Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].		Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].
	[[File:Image212_(2).jpg\|right\|~~200px~~\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]		[[File:Image212_(2).jpg\|right\|300px\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]

	== References ==		== References ==

Ephanrah: /* Stem Cells and Regeneration */

2021-04-12T23:49:07Z

Stem Cells and Regeneration

← Older revision		Revision as of 19:49, 12 April 2021
Line 11:		Line 11:
	== Stem Cells and Regeneration ==		== Stem Cells and Regeneration ==
	Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].		Neoblasts represent approximately 25%-30% of all planarian cells [1]. Neoblast regeneration and differentiation is activated by the WNT signaling pathway, a signal transduction pathway which specifies the anterior and posterior axis in development. "Wnt signaling directly targets the nucleus, and it is broadly used to regulate cell fate, proliferation and self-renewal of stem and progenitor cells in any tissue and at any stage of metazoan life" [6]. Specifically, this pathway specifies posterior axis development, however, in the absence of the Wnt ligand, the protein beta-catenin is degraded inhibiting posterior specification and enhancing anterior expression markers. Without the Wnt pathway properly activated, a planarian will regenerate with two anterior halves due to lack of posterior expression regulated by beta-catenin. Studies have shown how RNAi, also known as RNA silencing, can inactivate the beta-catenin gene resulting in a lack of posterior expression markers and structures in regenerated planarians [3].
			[[File:Image212_(2).jpg\|right\|200px\|RNAi of beta-catenin gene in S. mediterranea and regeneration following midsection cut]]

	== References ==		== References ==
	#Reddien, Peter W., and Alejandro Sánchez Alvarado. “Fundamentals of Planarian Regeneration.” Annual Review of Cell and Developmental Biology, vol. 20, no. 1, Annual Reviews, Inc, 2004, pp. 725–57, doi:10.1146/annurev.cellbio.20.010403.095114		#Reddien, Peter W., and Alejandro Sánchez Alvarado. “Fundamentals of Planarian Regeneration.” Annual Review of Cell and Developmental Biology, vol. 20, no. 1, Annual Reviews, Inc, 2004, pp. 725–57, doi:10.1146/annurev.cellbio.20.010403.095114