DEV2011 Lecture Notes - Adult Stem Cell, Embryonic Stem Cell, Umbilical Cord

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14 Sep 2013

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Stem cells are biological cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into diverse specialized cell types and can self-renew to produce more stem cells. In mammals, there are two broad types of stem cells: Embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues. Progenitor cells act as a repair system for the body, replenishing adult tissues. In a developing embryo, stem cells can differentiate into all the specialized cells (these are called pluripotent cells), but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues. The classical definition of a stem cell requires that it possess two properties: Self-renewal: the ability to go through numerous cycles of cell division while maintaining the undifferentiated state. Potency: the capacity to differentiate into specialized cell types.

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Multipotent versus restricted

Morphologically detectable neural crest cells usually are first observed as the cells individualize and delaminate upon emigration from the neural tube, following their epithelial to mesenchymal transition (EMT), in which they convert from a tightly adherent sheet of cells to a dispersed and more individual mesenchymal population. Prior to EMT, however, it is difficult or impossible at most axial levels and in most species to distinguish presumptive neural crest cells from cells that will form dorsal neural tube derivatives. However, there are exceptions, such as a subpopulation of cranial neural crest cells in chick and mouse that appears to be set aside and morphologically distinct at midbrain levels. In addition, some species such as axolotl have a clearly segregated population of neural crest cells that exists as a ridge on the dorsal neural tube.

A long-standing debate in the neural crest literature has been whether neural crest cells are multipotent and/or restricted in their developmental potential. In other words, can a single neural crest precursor form only one type of derivative or are the cells multipotent and able to produce multiple derivatives. Single cell lineage experiments (Bronner-Fraser and Fraser, 1988), in which individual cells within the chick dorsal neural tube are labeled with vital dye, show that some of the labeled clones contribute to multiple differentiated cell types in the periphery, including melanocytes, sympathetic and sensory ganglion cells. Thus, the original precursor was âmultipotentâ in its developmental potential to form neural crest derivatives. In addition to neural crest derivatives, single dorsal neuroepithelial cell also give rise both to migrating neural crest cells and cells that remain in the dorsal neural tube, such as roof plate cells and dorsal sensory neurons and/or interneurons. This suggests a shared lineage between the neural tube and neural crest, at least at this stage. However, labeling migrating neural crest cells in vivo also produced clones that could contribute to more than one neural crest lineage (Fraser and Bronner-Fraser, 1991), again supporting the idea that some of the migrating population retained multipotency.

Clonogenic culture of neural crest cells cultured shortly after their emigration from the neural tube definitely shows that many early migrating neural crest cells are multipotent in vitro as well (Baroffio et al., 1988, Calloni et al., 2007, Calloni et al., 2009, LeDouarin et al., 2008a, LeDouarin et al., 2008b, Sieber-Blum and Cohen, 1980 and Stemple and Anderson, 1993). Exposure to different growth factors can profoundly influence their lineage decisions (e.g. Lahav et al., 1998). Furthermore, they have a capacity for self-renewal, at least for a few cell divisions (Stemple and Anderson, 1993 and Trentin et al., 2004).

The fact that individual neural crest cells can form multiple derivatives has led to the idea that they have stem cell properties. Stem cells are defined as individual progenitor cells that can generate one or more specialized cell types. A cardinal feature of stem cells is their ability to self-renew, that is, to divide so as to give rise to at least one daughter cell that maintains the multipotent character of its parent. The fact that cloned neural crest cells have a limited ability to self-renew has led to the idea that they are stem-like (progenitors) cells rather than true stem cells. Interestingly, however, neural crest stem cells can be derived from adult tissues (Fernandes et al., 2008 and Shakhova and Sommer, 2010; see Chapter Dupin and Sommer), suggesting that they can remain quiescent for long periods of time or maintain long term self-renewal ability when left in situ.

The presence of some multipotent neural crest precursors cannot, however, rule out the possibility that other precursors may be more restricted in their developmental potential. In fact, experiments in zebrafish suggested that neural crest cells contribute to different sets of derivatives accordingly to their migration order (Raible and Eisen, 1994). However, if the leader cell was ablated, the next cell in line took up the fate that would have been filled by the ablated cell (Raible and Eisen, 1996). Similarly, early migrating neural crest cells normally exhibit a broader range of derivatives than later migrating cells; however, when the early population is ablated and replaced by late migrating cells, the late migrating cells assume a broader developmental potential than that prescribed by their normal fate (Baker et al., 1997). This raises a very important issue: that developmental potential is greater than or equal to a cell's normal fate. Only by challenging the cell by putting it into a new environment can one test for restriction of cell fate. This is best exemplified by experiments in which the potential of neural crest populations was challenged by performing heterotopic transplants between different axial levels (LeDouarin and Teillet, 1974), such as exchanging cranial and trunk, or vagal and trunk populations. The results demonstrate a combination of flexibility in cell fate and some axial level-autonomous characteristics. For example, cranial neural crest cells normally make cartilage and bone of the face whereas trunk neural crest cells do not. Transplantation of cranial neural folds to the trunk results in production of many normal trunk derivatives, as well as the formation of ectopic cartilage nodules (Le Lievre et al., 1980 and LeDouarin and Teillet, 1974). Conversely, transplantation of trunk neural folds to the head results in contributions to cranial neurons and glia of cranial ganglia, but not to cartilage, although some connective tissues and pericytes derive from this graft (Nakamura and Ayer-le Lievre, 1982). This reveals some flexibility in fate, but a more limited ability to form skeletal derivatives (LeDouarin et al., 2004). However, trunk neural crest cells can form cartilage in vitro under appropriate culture conditions (Calloni et al., 2007 and McGonnell and Graham, 2002). Because challenging prospective neural crest fate is a difficult experiment, it is much easier to prove multipotency than restricted cell fate, leaving the question of whether or not there are lineage-restricted neural crest precursors still open to debate (see Krispin et al., 2010).

1. Diseases are those abnormal conditionsin which the bodys defensive cells fail to make the self versus thenonself distinction correctly, and attack the body's owntissues.
A. Cancerous
B. Septic
C. Autoimmune
D. Nondiscrete

2. Which of the following determinesgenetic sex (male or female) in mammals?
A. the acrosome of the sperm
B. the temperature of the developing fetus
C. the SRY gene on the Y chromosome
D. the genetic makeup of the parents
E. the Y chromosome contained in the egg

3. Which of the following regardingantigens is true?
A. Antigens can only be recognized by their specificity.
B. An antigen is a molecule which promotes a general immuneresponse.
C. A large antigen is likely to have many different epitopes, eachof which can stimulate a distinct immune response.
D. The most effective antigen are small simple amino acidcomplexes.
E. Bacteria do not contain antigens.

4. All of the following are defensemechanism employed by vertebrates except

A. negative test, as in, not findingself-markers.

B. change in chromosomal composition

C. positive test to recognize presence ofnonself-markers

D. specific antibodies.

E. skin and mucous membranes asbarriers.

5. The immune system depends on thefunction of ______, which include several types of phagocytic cellsand two kinds of lymphocytes.

A. platelets

B. leukocytes

C. target cells

D. erythrocytes

6. In comparing the kidneys of marine andfreshwater fish, which of the following is not true?

A. Freshwater fish fluids have a greaterosmotic concentration.

B. Marine fish excrete many of the divalentcations through the anus.

C. The flow of the filtrate is faster inmarine fish.

D. The urine is less concentrated infreshwater fish.

E. Marine fish drink greater quantities ofwater.

7. The kidneys of which one of thefollowing are so highly efficient that it never has to drink waterand can obtain all of its water from its food?

A. desert lizard

B. camel

C. pocket moue Perognathus

D. kangaroo rat

E. gerbil

8. Select the incorrect statement regardingthe temperature of the immune system.

A. Interleukin-1 is a pyrogen, which cancause the neurons in the hypothalamus to raise the body'stemperature, producing a fever.

B. Fevers cause the liver and spleen tostore sodium and potassium which bacteria need for their growth andmetabolism.

C. Fevers above 105 Â° F can be fatal.

D. Fever contributes to the body's defensesby stimulating phagocytosis.

E. When macrophages encounter invadingcells, they release interleukin-1, which is carried to the brain bythe circulatory system.

9. Which of the following is not amechanism to prevent polyspermy?

A. change in membrane otential of egg

B. vitelline envelopes lift off surface ofegg

C. sperm nuclei degraded inside eggallowing one to fuse

D. cortical granule enzymes remove spermreceptors from egg

E. altering composition of exterior eggcoat

10. Which of the following cells have anincorrect function?

A. neutrophil---important antigenpresenting cell

B. eosinophil---important to theelimination of parasites

C. mast cell---releases histamine

D. macrophage---phagocytic cell

E. monocyte---precursor of macrophage

11. Which part of the antibody moleculedetermines its role in the immune response?

A. disulfide chains

B. the entire molecule

C. the stem of the Y

D. the heavy chains

E. two arms of the Y

12. Select the incorrectly matchedimmunoglobin (Ig)subclass and a fact about it.

A. IgG---found in the plasma and secretedin secondary response

B. IgM---first secreted during primaryresponse

C. IgE----promotes the release ofhistamine

D. IgA----found in saliva and motherÃ¢â¬â¢smilk

E. IgD----serve as receptors on thesurfaces of T cells

13. _______ are the source ofantibody-producing cells.

A. B cells

B. Plasma cells

C. Monocytes

D. Macrophages

E. T cells

14. Select the incorrect statementregarding the inflammatory response.

A. The alarm signals can be histamines orprostaglandins.

B. The inflammation response is a localizedspecific response to infection or injury.

C. Neutrophils spill chemical in the areaof injury or infection that kills bacteria, tissues, andthemselves.

D. Tissue can exhibit edema from thedilation of the blood vessels in the area of injury orinfection.

E. If a cell is injured or infected, itreleases chemical alarm signals that promote dilation of bloodvessels at the injury site.

15. Reproduction in reptiles compares toreproduction in birds in that

A. both newly hatched birds and reptilesrequire parental care.

B. the eggs of both birds and reptiles haveprotective shells.

C. birds are oviparous, reptiles areovoviviparous.

D. both exhibit external fertilization.

E. male or female reptiles reproduceasexually; birds do not.

16. ______diseases are those abnormalconditions in which the bodyÃ¢â¬â¢s defensive cells fail to make theself versus the nonself distinction correctly, and attack thebodyÃ¢â¬â¢s own tissues.

A. Cancerous

B. Septic

C. Autoimmune

D. Nondiscrete

17. Most marine invertebrates areosmoconformers. This means that

A. the osmolality of their body fluids isequal to that of the osmoregulators who inhabit the sameenvironments.

B. the osmolality of their body fluidsfluctuates between being hypertonic to hyportonic depending on theseason and the tides.

C. the osmolality of their body fluids isnot the same as their seawater environment

D. the osmolality of their body fluids isthe same as their seawater environment and that their bodiescontain the same solutes as their surroundings

E. the osmolality of their body fluids isthe same as their seawater environment

18. Which of the following determinesgenetic (male or female) in mammals?

A. the acrosome of the sperm

B. the temperature of the developingfetus

C. the SRY gene on the Y chromosome

D. the genetic makeup of the parents

E. the Y chromosome contained in theegg

If you can please explain why and how yougot the answer. 5 star rating for correct answers only, I have theanswer sheet, and just want to double check.

jadesnake579

Directions: Write out your answers in the word document and then copy and paste everything into the text box. If you do not include the question along with your answer, you will be marked down.

1. What would happen if you put pGLO directly onto an agar plate and you checked on it after letting it incubate?

a. It would glow

b. It would grow

c. Nothing

d. E.Coli would grow

2. Explain in a short sentence or two your reasoning for question 1.

3. What shape is a plasmid?

4. How is a plasmid different from human DNA? Write one difference.

5. Bacteria can share DNA through a unique method called transformation. What are the TWO requirements a bacteria cell must possess in order to share DNA with another bacteria cell?

6. Why during our experiment did we put our e.Coli with pGLO inserted in it onto agar plates with ampicillin (Amp)?

a. So that it would kill the e.Coli and serve as our control

b. To kill all the e.Coli that did not take up the pGLO

c. To create antibiotic resistant bacteria

d. To cause the e.Coli to glow

7. Yeast cells are what type of cell?

a. Bacteria

b. Eukaryotes

c. Prokaryotes

d. Archaea

8. Why would someone study yeast cells instead of human cells?

9. Do you agree or disagree with the following statement: If your cells is exposed to UV light and it causes a thymidine dimer, your cell is doomed to die.

10. Are wildtype (control) yeast immune to UV light damage?

11. BTB was a dye we used to directly measure ________

a. PH

b. Oxygen

c. Carbon Dioxide

d. Carbon

12. BTB was a dye we used to INDIRECTLY measure ________

a. PH

b. Oxygen

c. Carbon Dioxide

d. Carbon

13. What is one reason why a plant would want to close its stomata?

14. What is one function that ground tissues provides for a plant?

15. List one difference between monocots and dicots

16. Why is it important for a plant to have stomata? Write one reason why

17. What is the purpose of xylem in a plant cell?

18. Pholem is also important to plant cells, what is itâs purpose?

19. This theory explains why trees can grow to such tall heights and still provide water to their leaves.

a. Translocation

b. Transpiration

c. Cohesion-Tension

d. Vacuum

20. Fill in the blank

Pholem is considered to be a(n) _________ transport system while xylem is considered a(n) _______________transport system.

21. Apical meristems are found in these two places on a plant

a. At the site of new leaf growth and the roots closes to the top of the soil

b. Vascular tissue and ground tissue

c. Ground tissue and dermal tissue

d. The point of new growth on the stem and root

22. Fill in the blank.

Xylem moves substances _____ while phloem moves substances _____ a plant.

23. What are the two types of digestive mechanisms?

24. What is one benefit that mastication has for digestion?

25. What is an example of an organism that digests food intracellularly?

26. What is an example of an organism that digests food extracellularly?

27. Give two examples of where surface area is increased in a small space to aid in absorption within the human body

28. Name one difference between arteries and veins.

29. What is the role of capillaries in the circulatory system?

30. How are the terms âexcretionâ and âdefecationâ different?

31. What is the role of the ADH hormone?

32. What does the term âMedullaâ refer to when talking about mammalian tissue?

a. The outer edges of a tissue

b. The middle of a tissue

c. The top of a tissue

d. The bottom of a tissue

33. Fill in the blank

Mammals have a _______ circulatory system while insects have a _______ circulatory system.

34. What is one benefit a closed circulatory system provides?

35. What is hemolymph?

DEV2011 Lecture Notes - Adult Stem Cell, Embryonic Stem Cell, Umbilical Cord

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