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ORGANOGENESIS

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Kader Mullah

Organogenesis is the development of organs after the formation of the three germ layers in an embryo. Vulva formation in the nematode C. elegans is regulated by an inductive signaling process. Specifically, one cell called the anchor cell secretes LIN-3, a growth factor, which activates a receptor tyrosine kinase pathway in six vulva precursor cells. Based on their proximity to the anchor cell, these precursor cells are specified to one of three fates: the central cells directly beneath the anchor cell form the central vulval cells, the adjacent cells form the lateral vulval cells, and cells farther away form hypodermal cells instead of vulval cells.

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ORGANOGENESIS VULVA FORMATION IN CAENORHABDITIS ELEGANS PRESENTED BY MD KADER MULLAH
ORGANOGENESIS INTRODUCTION: The production and development of organs after the formation of three germ layers in embryo is know as ogranogenesis.
VULVA FORMATION IN CAENORHABDITIS ELEGANS a. Mostly caenorhabditis elegans individuals are hermaphrodites. b. In early development-they are male and gonad produces sperm. c. When they grow old- they develop ovaries.
Formation of vulva in caenorhabditis elegans is simply a case in which one inductive signal generates a variety of cell types. This organ forms during the larval stage from six cells called vulva precursor cells. The cell connecting the overlying gonad to the vulval precursor cells is called anchor cell.
The anchor cell secretes the LIN-3 protein, a paracrine factor(similar to mammalian epidermal growth factor , or EGF) that activates the RTK (receptor tyrosine kinase pathway). If the anchor cell is destroyed the PVCs will not form a vulva but instead become part of the hypodermis(skin).
The six VPCs influenced by the anchor cell form an equivalenve group. Each member of this group is competent to become induced by the anchor cell and can assume any of the three fates,depending on its proximity of the anchor cell. The cell directly beneath the anchor cell divides to form the central vulval cells.
The two cells flanking that central cell divide to become the lateral vulval cells , while the three cells farther away from the anchor cell generate hypodermal cells. If the anchor cell is destroyed , all six cells of the equivalence group divide once and contribute to the hypodermal tissue.
If the three central VPCs are destroyed , the three outer cells , which normally form hypodermis , generate vulval cells instead. The LIN-3 protein is received by the LET-23 receptor tyrosine kinase on the VPCs , and the signal is transferred to the nucleus through the RTK pathway. The target of the kinase cascade is the LIN-31 protein.
ORGANOGENESIS
When this protein is phosphorylated in the nucleus , it loses its inhibitory protein partner and is able to function as a transcription factor , promoting vulval cell fates.
MECHANISM The LIN-3 protein forms a concentration gradient. here , the VPC closest to the anchor cell, receives the highest concentration of LIN-3 protein and generates the central vulval cells.The two VPCs adjacent to it (P5.p and P7.p) receive a lower amount ofb LIN-3 and become the lateral vulval cells. The VPCs farther away from the anchor cell do not receive enough LIN-3 to have an effect, so they become hypodermis.
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ORGANOGENESIS

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ORGANOGENESIS

  • 1. ORGANOGENESIS VULVA FORMATION IN CAENORHABDITIS ELEGANS PRESENTED BY MD KADER MULLAH
  • 2. ORGANOGENESIS INTRODUCTION: The production and development of organs after the formation of three germ layers in embryo is know as ogranogenesis.
  • 3. VULVA FORMATION IN CAENORHABDITIS ELEGANS a. Mostly caenorhabditis elegans individuals are hermaphrodites. b. In early development-they are male and gonad produces sperm. c. When they grow old- they develop ovaries.
  • 4. Formation of vulva in caenorhabditis elegans is simply a case in which one inductive signal generates a variety of cell types. This organ forms during the larval stage from six cells called vulva precursor cells. The cell connecting the overlying gonad to the vulval precursor cells is called anchor cell.
  • 5. The anchor cell secretes the LIN-3 protein, a paracrine factor(similar to mammalian epidermal growth factor , or EGF) that activates the RTK (receptor tyrosine kinase pathway). If the anchor cell is destroyed the PVCs will not form a vulva but instead become part of the hypodermis(skin).
  • 6. The six VPCs influenced by the anchor cell form an equivalenve group. Each member of this group is competent to become induced by the anchor cell and can assume any of the three fates,depending on its proximity of the anchor cell. The cell directly beneath the anchor cell divides to form the central vulval cells.
  • 7. The two cells flanking that central cell divide to become the lateral vulval cells , while the three cells farther away from the anchor cell generate hypodermal cells. If the anchor cell is destroyed , all six cells of the equivalence group divide once and contribute to the hypodermal tissue.
  • 8. If the three central VPCs are destroyed , the three outer cells , which normally form hypodermis , generate vulval cells instead. The LIN-3 protein is received by the LET-23 receptor tyrosine kinase on the VPCs , and the signal is transferred to the nucleus through the RTK pathway. The target of the kinase cascade is the LIN-31 protein.
  • 10. When this protein is phosphorylated in the nucleus , it loses its inhibitory protein partner and is able to function as a transcription factor , promoting vulval cell fates.
  • 11. MECHANISM The LIN-3 protein forms a concentration gradient. here , the VPC closest to the anchor cell, receives the highest concentration of LIN-3 protein and generates the central vulval cells.The two VPCs adjacent to it (P5.p and P7.p) receive a lower amount ofb LIN-3 and become the lateral vulval cells. The VPCs farther away from the anchor cell do not receive enough LIN-3 to have an effect, so they become hypodermis.