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Revision as of 11:55, 23 September 2012 by Z3333794 (talk | contribs) (→‎Lab 8)

Lab Attendance

Lab 1 --Z3333794 10:59, 25 July 2012 (EST)

Lab 2 --Z3333794 10:02, 1 August 2012 (EST)

Lab 3 --Z3333794 10:10, 8 August 2012 (EST)

Lab 4 --Z3333794 10:04, 15 August 2012 (EST)

Lab 5 --Z3333794 09:49, 22 August 2012 (EST)

Lab 6 --Z3333794 10:07, 29 August 2012 (EST)

Lab 7 --Z3333794 10:07, 12 September 2012 (EST)

Lab 8 --Z3333794 10:04, 19 September 2012 (EST)

Lab Exercises

Lab 1

Identify the origin of In Vitro Fertilization and the 2010 nobel prize winner associated with this technique and add a correctly formatted link to the Nobel page.

The roots of InVitro Fertilization (IVF) and Embryo Transfer (ET) dates back to the early 1890s where Walter Heape a dedicated professor and physician at the University of Cambridge in England whereby he reported the first case of embryo transplant in rabbits. He then went on to do more research in the field of reproduction on a variety of animal species. IVF history

IVF worldwide also articulates that the first in vitro fertilization of human oocytes was carried out in 1965 in John Hopkins Hospital, USA by Edwards and Jones and the first IVF pregnancy occurred in 1973 in the Melbourne, Australia by researchers Wood and Leeton. The pregnancy led to a miscarriage and the first IVF baby was born in England on 25th July 1978, 5 years later. IVF history

The 2010 Nobel prize in Physiology and Medicine was awarded to Robert G. Edwards for development of in vitro Fertilization. His contribution to embryology made a worldwide impact as it became a viable way to overcome infertility. [Nobel Prize Winner 2010]


Identify and add a PubMed reference link to a recent paper on fertilisation and describe its key findings (1-2 paragraphs).

In Vitro Fertilization technology has not only impacted humans as a way to overcome infertility but has majot implications for the animal society as well. It is used in breeding practices throughout the world to breed the best quality animals. To make sure the treatment is cost effective it is imperative that the process of IVF leads to a successful pregnancy and as a result birth. Research carried by Jimenez et.al., 2011 focuses at investigating the link between thickness of zona pellucida fertilization, embryo implantation and birth. By using video chromatography their team successfully concluded that the thickness of zona pelucida greatly impacted the fertilization process and transplantation but did not significantly impact in birth.

<pubmed> 22607772 </pubmed>


Lab 2

Adding an Image with the class

GnRH receptors (GnRHRs) and spatial expression patterns of gnrhr genes.png

Online Lab Questions

Upload an image from a journal source relating to fertilization or the first 2 weeks of development.

Expression of CD82 in human placental villi and cell lines.JPG

Identify a protein associated with the implantation process, including a brief description of the protein's role.

The Rac-1 protein [[1]] belongs to a family of small GTPase binding protein called the RAS superfamily. This protein plays an important role in various cellular processes like cell motility, cellular growth, cell cycle and also cell-cell adhesion. Studies done by Grewal et.al., 2008 demonstrate that the invasion of the human embryonic tropoblast layer into the human endrometrial stromal cells requires mediation by the Rac-1 protein. Increased motility of the stromal cells increases the chances of implantation and an increased expression of Rac-1 activation corresponds with increase in motility. Rac-1 also works by down-regulating RhoA protein which is also important to promote embryo invasion. Since, successful implantation is imperative for pregnancy and fertility the role of Rac-1 is somewhat central to the process of implantation.

<pubmed> 18838676 </pubmed>


Lab 3

Identify the difference between "gestational age" and "post-fertilisation age" and explain why clinically "gestational age" is used in describing human development.

Gestational age is defined as the time period between conception and birth. It helps the clinicians determine how far along a women is in her pregnancy and is taken from the first day of the women's last menstural cycle (LMC). This is measured in weeks with a normal pregnancy lasting between 38-42 weeks. [Plus - Gestational Age]

Post fertilization age on the other hand is the time lapsed after the sperm enters the oocyte and cell division begins.

Gestational age is used as opposed to post fertilization age as it is easy to determine when the woman had her last menstrual cycle whereas the exact day/time of fertilization is hard to determine. Gestational age is easy to determine both before and after birth. While the foetus is growing it's size of the head, thigh bone and abdomen can be used to establish the gestational age. After the birth the length, size of the head, weight and other vital signs can be used to determine gestational age. Babies born before 37 weeks are said to be premature whereas after 42 weeks are post mature.

Clinically the infant's medical history and medical plan is determined based on the gestational age.


Identify using histological descriptions at least 3 different types of tissues formed from somites.

Histologically somite differentiate into dermis, cartilage and muscle.

The ventral medial portion of the somite becomes the sclerotome via Sonic hedgehog signalling mechanism. Transcription factor Pax 1 then converts the sclerotome into cartilage tissue imperative for the functioning of the vertebrae.

The dorsal portion of periaxial mesoderm is the dermatome which in response to factor neurotropin 3 changes into the dermis.

The medial portion of the somite expresses Wnt1 and Wnt3 factors that converts the myotome into expressing muscle related genes. Similarly Wnt proteins and bone morphogenetic protein 4 (BMP4) cause the expression of muscle related genes in the lateral portion of the somite.

Biology. 6th edition. Gilbert SF. Sunderland (MA): Sinauer Associates; 2000. Paraxial Mesoderm: The Somites and Their Derivatives


Lab 4

Identify the 2 invasive prenatal diagnostic techniques related to the placenta and 2 abnormalities that can be identified with these techniques.

Chronic Villus Biopsy (CVB) or placental biopsy which involves use of a catheter through the cervix or transabdominal needle into the uterus in order to obtain placental tissue. Since the placenta is derived from the cells of the embryo it contains the genetic material of the foetus which can used for chromosomal analysis. The test is performed within 10-12 weeks of pregnancy and can be used to identify a range of genetic mutations (although not all) like Down's syndrome and Turner syndrome.

Amniocentesis is another invasive technique in which a needle is used to obtain a sample of the amniotic fluid via passing it through the mother's abdomen. It is normally performed between 14 to 20 weeks of gestation and is also used to account for any genetic abnormalities. The amniotic cells can be examined either by fluorescent techniques or by culturing them further. Along with chromosomal anomalies this procedure can also be used to diagnose for congenital metabolic diseases, neural tube defects, hereditary related genetic diseases like cystic fibrosis etc.

References

TESTING – CVS AND AMNIOCENTESIS

Prenatal diagnosis

Diagnosis

<pubmed> 16533654 </pubmed>

Identify a paper that uses cord stem cells therapeutically and write a brief (2-3 paragraph) description of the paper's findings.

<pubmed> 19156219 </pubmed>

Type 1 diabetes is a form of autoimmune disease involving destruction of beta cells of the pancreas which produce insulin that helps in maintaining glucose homoeostasis in the body. Deficiency of insulin causes an elevation in glucose levels of blood and urine. Normal treatment of insulin involves insulin injections which is administered daily to the patient. Although the treatment helps to replace the lost insulin it does not solve the autoimmunity problem. Studies done by Zhao et.al., 2009 indicate that using human cord blood stem cells in non obese diabetic mice helps to fight hyperglycaemia and helps restore original architect of the islets of langerhans by causing beta cell regeneration, increase in mass of beta cells and production of insulin.

By using immunostaining techniques showed that the diabetic rats that were untreated had around 80% of their beta cells destroyed whereas the diabetic rats that were treated with cord blood stem cells had a high proliferation rate of beta cells hence proving to be promising therapeutic agent to treat type 1 diabetes. Human cord stem cells can prove to be a viable treatment for type 1 diabetes as it does not involve any immune problems nor does it attract any ethical controversies. There is also a large resource available for cord blood worldwide.

Lab 5

Finish survey!

Lab 6

Working on group project

Lab 7

Provide a one sentence definition of a muscle satellite cell (b) In one paragraph, briefly discuss two examples of when satellite cells are activated ?

Satellite cells are a small population of quiescent muscle stem cells that reside in the skeletal muscle.

<pubmed>12757751</pubmed>

Short bursts of resistive activity or physical injury that causes chronic stress to the muscle can induce a hypertrophic response and recruitment of satellite cells. Since the integrity of satellite cells is maintained by the intactness of basal lamina any interruption during muscle trauma causes the cells might proliferate the adjacent myofibres. The cells can also travel via chemotaxis to the site of injury. After injury macrophages are recruited to the site as a result of immune response. These macrophages release a number of cytokines essential for recruitment, proliferation and differentiation of the satellite cells.

<pubmed>11457764</pubmed>


In one brief paragraph, describe what happens to skeletal muscle fibre type and size when the innervating motor nerve sustains long term damage such as in spinal cord injury?

Long-term injury of the spinal cord damages the innervating motor nerve thus removing the connection between the nerve and the muscle thus depriving the muscle of various neurotropic factors. Over long term, atrophy develops as a result of disuse of the muscle causing degeneration of the myofibril and decrease in the number of satellite cells. Studies have found a decrease in the percentage of satellite cells to as low as 1% following an 18 month old nerve injury. Neurotropic factors are important for providing the growth factors for maintenance of the satellite cell population and denervation negatively impacts its function. After a period of prolonged denervation even if the nerve sprouts back the muscle cannot regain its lost function due to decrease in the reserve pool of satellite cells.

<pubemd> 9214552</pubmed>

Lab 8

Critical analysis of group projects

Group 2 - Somatosensory

- The introduction is small yet detailed --- I like how its an overview of the development. You do need to fix up the references though.

- You have in the intro section “the following picture….” But there is no picture there….if the picture is further ahead maybe write Fig 1 shows….and also label the picture.

- History section needs a bit work on – you should start with the earliest data and proceed in a chronological order so everyone can see the advancement in development of somatosensory organs.

- In the section of “Development of the primary somatosensory cortex” you have mentioned that there are intrinsic and extrinsic mechanisms --- you should mention what those signalling mechanisms are. Also if you are using the one ref for the whole paragraph do not put the ref after each line. Just put it in the end. Also it would be good to give the origin of the neurons like ecto, endo or meso. - Its good how your description is divided into stages – it might help to give the weeks as well.

- For the touch section you have a lot of detail on what the receptors are which is fine but there is nothing about their development (which is what the project is about). The same thing is noted with “Pain” section – there is nothing on development. I’m sure you can put some genes or signalling molecules that are important for differentiation of cells into the different receptors.

At the moment your project is focused on what the different somatosensory receptors do but very little detail on how they develop, which is what you need to focus on. More pictures are needed to break up the text.

Group 3 - Olfaction

- The introduction of taste is very descriptive and encapsulates the anatomy, physiology and cell biology. Although it is very detailed it doesn’t indicate that the project is about development.

- There is a lot of detail about the taste neural pathway and cortical areas which I’m not sure is relevant to olfactory development unless you mention how they develop as well.

- Figure 2 and 3 do not have any copyright information associated so remember to add those.

- The development section is very nicely put together and hopefully you will add images further down the line. I’ve noticed that in week 8 of development you have the same ref after each line…I’m sure you can just put it at the end of the paragraph as it is same for each line. Same goes for week 14 and 15. Also since you have 2 references for the entire section --- you might want to look at other articles as well.

- Some things that I missed in the section were patterning molecules and genes. Also any signalling mechanisms that control differentiation.

- The history section is exceptionally done with the use of tables, description and references.

- I thoroughly enjoyed your abnormality section. The images are nicely done as well. Although you have described many genes and molecules which are not specified in the normal development portion so the reader don’t understand their roles. Maybe address this in your normal development section.

- The current development section is also very nicely put together but again things like Shh and WNT should be in development section.

Overall very nicely put together and great balance of pictures and text. Although this is a development topic so the major emphasis should be on development of the organ --- Normal development is good but there is too much content in that section that can be left out.