Nuclear fission processes can provide a lot of energy but

PNB 3260 Exam 2 material Anna Ciara Mason Lec 10: Adult stem cells and adult stem cell niches Adult stem cell niche  adult stem cells are quiescent (periods stopped in one spot in cell cycle/division) o increased division can increase mutation potential o divide infrequently to generate one stem cell copy and a rapidly cycling cell  Microenvironment is both proliferation-limiting and differentiation-limiting o type of cells made, extent of differentiation etc.  Niche is unique for each organ and tissue type o there are many overlapping systems  Required for day to day physiological replacement and injury related replacement in an organ  Rapidly cycling cells (transit-amplifying cells) undergo a limited number of cell divisions before terminally differentiating to functional cells of tissue  symmetric division- cancer treatments may lower amount of stem cells. quiescent stem cell that wasn't targeted in the chemotherapy can start dividing  stem cell can generate 2 transindental cells - lose cell line o stem cell might only be able to undergo a certain amount of divisions Stem cell niches  A) A germination of the ovary o organization is important in the ovary and testes  stem cells attach to somatic cells to anchor themselves  B) the apex of the testes o only stem cells that are attached to hub will remain as stem cells - limits number of stem cells possible  C) The subventricular zone (SVZ) of the brain o 2 stem cell niches in the brain  subventricular zone - rodents  humans - pretty much limited at 2 years old  epithelial cells that line the ventricle - stem cells attach here and also help to circulate cerebral spinal fluid  stem cells generate these epithelial cells  D) Hair follicle as a niche o Regeneration of hair follicles in skin ~1 - 1.5 months  E) The crypt of an intestinal villus o Protected region where stem cells are located because so much is coming through  F) The bone marrow o Hemaptopoetic also attached to stromal cells in bone marrow o can go on to make multipotent o can make lymphoid or myloid lineages Asymmetric vs Symmetric cell division  only a certain number of stem cells can go around a hub- way of restricting the stem cells  committed cell is trans and amplifying cell Adherens junctions  help maintain stem cells in niche via somatic cell contact Adult stem cells  divide relatively infrequectly depending on organ system  generate one stem cell copy and rapidly cycling cell (transit-amplifying cell)  transit-amplifying cell: limited number  ** Intestine  Lining made up of villi to increase the surface area  Complete cell turn over: 2-3 days  Each villi has a crypt area and each contribute to the cells that line the villa  Intestinal stem cells (ISCs) o secrete antimicrobials o red are molecular signals from crypt o 2 kinds of stem cells  +4 markers  label retention  cell takes up marker in division  if cell is quicent - keeps marker  if division continues then marker will be diluted  CBC markers  not label retaining - means they are more actively proliferating o localized in intestinal crypt o regenerate entire villus every 3-5 days o Generate paneth, enteroendocrine o cells at top of villus are constantly shedding Stomach  lining of stomach is highly regenerative  pyloric region is most studied  stem cells are found throughout but we're talking about pyloric  adult stem cell-driven epithelial renewal in the pyloric stomach o pit mucus cell, parietal (oxyntic) cell, gland mucus cell, endocrine cell o took out LGR5 positive stem cell and cultured it to form an organoid similar to stomach Hair follicle stem cells (HFSCs)  budge surrounds entire follicle  Skin transplantation assays o different skin stem cell classes are capable of generating all epidermal lineages in skin transplantation assays o stem cells mixed with neonatal dermal fibroblasts and implants onto back of immuno- compromised nude mice o niche defines the differential potential of otherwise equivalent stem cell populations Cre-recombinase-based lineage tracing system  No tamoxifen vs tamoxifen  tamoxifen activates CRE enzymes which cuts 2/25/2016 12:59:00 PM 2/25/2016 12:59:00 PM