Heidi's Blog for Developmental Biology

BUBBLES!!!

2013-04-30T04:09:09Z

This week we were suppose to do our chick lab. Unfortunately, due to the weather, the poor chick eggs froze. Because of that, our professor replaced this lab with a bubble lab! We made solution out of D.I. water, glycerol, and dawn soap. Here are my results!

The purpose of making these bubbles was to resemble multicellular organisms and their differentiation. The connection with the bubbles were observed to see how they followed rules of organization.

It was a fun lab, and now I know how to make bubbles!!!! :)

Fruit Fly Behavior

2013-04-18T02:06:37Z

For the past couple weeks, the lab assignment was to take a video of some kind of fruit fly behavior like mating or hatching. My partner and I wanted to do it on mating because I am also in a genetics lab, so I have easily accessible virgin females. However, we had several issues with this lab. The camera wasn't working at first, and then the computer program wasn't working. We tried 3 times to do this assignment before actually getting some footage. We waiting for a really long time for the flies to wake up, and then after 2.5 hours, they still weren't interested in mating. Because of this, we took a video of just their behavior, which was wiping their wings and head. This is show in the video:

The last time we attempted to do this lab, we had everything set up, and since there weren't any current problems with the technology, we didn't think we had to test anything. However, when the flies started to mate, we could not get the camera to record onto the computer.

This lab was frustrating, but it was still interesting to see all of the behaviors. I wish we could have gotten it on video, but maybe another time.

Chicken Development

2013-04-11T04:40:00Z

Next week in lab, we are suppose to start chicken development. Therefore, I thought it would be good to read up on this topic so that I am prepared for lab. With only 31 days left until graduation, I hope that we have enough time to finish this lab since the chicken develops and hatches in 20-21 days.

I will assume that we will be keeping the fertilized eggs in the incubator. I guess a humidified incubator is best, but I don't know what kind of incubator is in the lab.

All of the information below is from Mississippi State Universities website. [http://msucares.com/poultry/reproductions/poultry_chicks_embryo.html]

EVENTS IN EMBRYONIC DEVELOPMENT

Before Egg Laying:
Fertilization
Division and growth of living cells
Segregation of cells into groups of special function (tissues)

Between Laying and Incubation
No growth; stage of inactive embryonic life

During Incubation:

First day

16 hours - first sign of resemblance to a chick embryo
18 hours - appearance of alimentary tract
20 hours - appearance of vertebral column
21 hours - beginning of nervous system
22 hours - beginning of head
24 hours - beginning of eye

Second day

25 hours - beginning of heart
35 hours - beginning of ear
42 hours - heart beats

Third day

60 hours - beginning of nose
62 hours - beginning of legs
64 hours - beginning of wings

Fourth day - beginning of tongue

Fifth day - formation of reproductive organs and differentiation of sex

Sixth day - beginning of beak

Eighth day - beginning of feathers

Tenth day - beginning of hardening of beak

Thirteenth day - appearance of scales and claws

Fourteenth day - embryo gets into position suitable for breaking shell

Sixteenth day - scales, claws and beak becoming firm and horny

Seventeenth day - beak turns toward air cell

Nineteenth day - yolk sac begins to enter body cavity

Twentieth day - yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cell

Twenty-first day - hatching of chick

I also thought it would be interesting to read up on some interesting facts about chickens. This is what I found:
-the chicken is the closest living relative of the t-rex
-a chickens heart beats 280-315 times a minutes
-9 egg yolks have been found in one chicken egg

http://voices.yahoo.com/20-little-known-facts-chicken-387377.html?cat=22

Telomeres and Caloric Restriction

2013-03-24T23:34:24Z

I came across a paper that was published at the beginning of this year that discusses how restricting calorie intake can protect chromosomes. I consider this topic part of developmental biology because I think that aging is still part of development. This type of development is just less positive because it has negative effects.

Telomeres are known to be the judgement of aging. They are located at the ends of chromosomes, and the more humans age, the shorter the telomeres get due to DNA replication. Reduced telomeres can increase the risk of cancer and other age-related illnesses. Vera and colleagues studied adult mice and found that lowering the mice caloric intake over time results in a delay of telomere shortening.

Literature Cited:

Elsa Vera, Bruno Bernardes de Jesus, Miguel Foronda, Juana M. Flores, Maria A. Blasco. Telomerase Reverse Transcriptase Synergizes with Calorie Restriction to Increase Health Span and Extend Mouse Longevity. PLoS ONE, 2013; 8 (1): e53760 DOI: 10.1371/journal.pone.0053760

Melanin

2013-03-24T21:25:19Z

Melanin is present in human's skin, hair, and eyes. It is also important in protecting the skin from UV radiation. Melanoblasts rise from the neural crest in the developing embryo; in particular, the second month of development. The destination of these melanoblasts include the dermis, epidermis, uveal tract of eye, hair follicles, the stria vasculare, the vestibular organ and endolymphatic sac of the ear, and leptomeninges of the brain. Migration and development in the dermis takes 10-12 weeks and 12-14 weeks for the epidermis. Upon reach of destination, the melanoblasts differentiate into melanocytes, which typically occurs at six months in the developing fetus. Melanocytes in the epidermis continue to replicate and produce melanin; whereas, the dermal melanocytes decrease in number during gestation, and eventually disappear at birth.

Melanin synthesis occurs in membrane bound organelles called the melanosomes, which are produced by the melanocytes. The differences in skin color between people is based on cutaneous pigmentation. After production of melanin by melanocytes, the melanosomes must be transferred to surrounding keratinocytes. The abundance of melanocytes relatively constant in all skin types; however, the size and distribution differs within keratinocytes. The difference between dark and light skin color is that darker skinned people have many large and dense melanosomal particles; whereas, light skin color has smaller particles and are less dense. The melanosome type and distribution is present at birth.

The mechanism for how melanin helps to protect the skin from UV radiation is melanin accumulates above the nucleus and absorbs the UV-rays before they reach the nucleus and damage the DNA.

Literature Cited:

Costin, G.E., Hearing, V.J. 2007. Human skin pigmentation: melanocytes modulate skin color in response to stress. The FASEB Journal. 21(4): 976-994.

Ear development, infection and evolutionary glitch

2013-03-24T20:53:37Z

An article was published a few days ago (March 21) that is going to cause textbooks to be re-written because of what they found. Thompson and Tucker used transgenic mice to track the developmental process of the middle ear. The mechanism that they found gives a reason why the ear is prone to infection. Two types of tissues are used when developing the middle ear, which are the neural crest and the endoderm. The difference between these two types of tissues is that the endoderm gives rise to the tissue lining that is covered with cilia; whereas, the neural crest gives rise to he tissue lining with absence of the cilia. The purpose of cilia is to remove debris from the ear. Therefore, the tissue that originate from the neural tube are not efficient at removing debris due to the lack of cilia.

The middle ear is a air filled space, something that is unique to mammals. Reptiles and birds do not have this air filled space, probably because they only have one ear bone, while mammals have three. It is suggested that the evolved air filled spaced was needed to proved room for the additional two bones. Thus, the two types of tissue lining in the middle ear might have evolved due to the air filled space. Even though the evolution of these two types of tissues was to make space for the additional two bones needed for hearing in the mammals ear, it allowed the chances of infection to increase. The lining with no cilia cannot efficiently remove debris from the ear, leading it to be more prone to infection. This was discussed in the review as an "evolutionary glitch".

Literature Cited:

Hannah Thompson and Abigail S. Tucker. Dual Origin of the Epithelium of the Mammalian Middle Ear. Science, 2013; 339 (6126): 1453-1456 DOI: 10.1126/science.1232862

http://www.sciencedaily.com/releases/2013/03/130321141453.htm

Review of Mile's Blog on Gynandromorphy

2013-03-04T21:23:08Z

For our class blog assignment this week, professor Myers wanted us to read a blog from another student, comment, and then write our own blow review it.

Miles' blog on gynandromorphy!

Going over the different entries, the half red half white bird caught my eye. This blog written by Miles is on gynandromorphy. Gynandromorphy is a condition where an organism has both male and female parts. The picture in this blog is of a cardinal. This occurs when the sex chromosomes do not separate equally in mitosis, and this causes a cell to contain both male and female sex chromosomes. An example is for a male (XY) to produce a cell with X and the other with XYY. The XYY cell then can develop into an organism that has bilateral symmetry of male and female structures.

I asked on his blog which color represents which sex. With some of my own research. It turns out that the male would be red reflecting the idea of sexual selection where the brighter color would attract females. The female would be a mix of a dull grey/white/red. I also asked if the organism is hermaphroditic. It turns out that hermaphrodites have reproductive organs or male and female, but the exterior characteristics are normal. An example is that there may be a butterfly that is a female, but has a male wing.

This condition is unique to cardinals because it does not occur in other birds. However, it does happen to other organisms like the butterfly shown below:

Tiger swallowtail: Males are yellow with black stripes, while females appear a dark blue.

Picture was from: http://e11e-k.deviantart.com/art/Gynandromorph-208458484

BPA and neurodevelopmental disorder?

2013-03-01T04:13:58Z

On February 25, 2013 the journal Proceedings of the National Academy of Sciences published an article by Michele Yeo and colleagues on BPA and how it could cause neurodevelopmental disorders. BPA (bisphenol A) is a chemical that has hormone like qualities similar to estrogen. It can be found in the plastic materials in the environment, which can 'leak' into edible items (like water from a water bottle). This ingestion can lead to health problems like cancer and reproductive disorders.

In this paper, they found that BPA can impair central nervous system development. They did experiments to try to figure our how BPA exposure can lead to this using rodents and human nerve cells.

First of all, the development of neurons occurs with chloride presence. When the neurons are developing, there are high levels of chloride, and when the levels drop, the neurons are able to mature. KCC2 is a chloride transport protein that aids in removal of the chloride. It is known that if the level of chloride is not removed, damage can occur to the developing neurons by damaging neural circuits and "preventing" migration of the nerve cells to the appropriate position in the brain.

When BPA exposure is elevated the Kcc2 gene is shut down leading to altered altered levels of chloride in the neurons. This gene is responsible for making KCC2 protein. If that protein can not be made, then chloride regulation will be in trouble with a delay in removal. It was found that MECP2, which is a protein involved in normal brain function could be responsible for shutting down Kcc2 gene. MECP2's abundance increases during exposure of BPA. MECP2 binds to Kcc2 and shuts down the gene.

An interesting finding is that female's neurons were more sensitive to BPA exposure compared to males males. Further studies will be needed to give answers for this interesting finding, and if some sex hormone receptors, like estrogen, are involved with the relation of BPA and KCC2.

In summary, BPA exposure is involved with normal neuron development by effecting Kcc2 gene regulation.

Literature Cited:
Michele Yeo, Ken Berglund, Michael Hanna, Junjie U. Guo, Jaya Kittur, Maria D. Torres, Joel Abramowitz, Jorge Busciglio, Yuan Gao, Lutz Birnbaumer, and Wolfgang B. Liedtke. Bisphenol A delays the perinatal chloride shift in cortical neurons by epigenetic effects on the Kcc2 promoter. PNAS, February 25, 2013 DOI: 10.1073/pnas.1300959110

Webbed Toes

2013-02-20T04:54:28Z

Syndactyly is a name that means webbed fingers. Webbed toes is when two or more toes are fused together. In early fetal development, all human's toes and fingers are webbed together. They are separated by apoptosis that occurs by a specific enzyme. Therefore, webbed toes occur when this apoptosis either does not occur or is incomplete.

There are six different types:

Simple: adjacent fingers/toes joined by soft tissue and skin
Complex: bones of adjacent fingers or toes are fused together
Complete: the skin is joined the entire length of the digits
Incomplete: the skin is joined partially up the digit, usually to the first joint
Fenestrated: the skin is joined for most of the digit, but there is a gap in the middle of the joined skin
Polysyndactly: there is an extra digit webbed to an adjacent digit.

The cause of this is still unknown, but women smoking during pregnancy or a women's nutritional intake during early gestation can contribute. It is a side effect to over 100 different diseases, and it does occur in families.

Development abnormalities

2013-02-17T22:11:35Z

I was curious as to what kind of development abnormalities that have occurred and this is what I found:

First of all, down syndrome is the most common chromosomal abnormality affecting 1 in 800 babies. The chances of this happening increases as the mother ages. The problem is due to an extra 21 chromosome. This leads to an over expression of those genes.

Another one that I came across is called harlequin-type ichthyosis. This is a skin disease characterized by thickening of the keratin layer in fetal human skin. What happens in the the skin contains massive, diamond-shaped scales that tend to be a reddish color. Besides that, the ears may be very poorly developed or absent entirely, same for the nose. The eyelids everted, and often bleed upon birth. the lips are fixed into a wide grimace. Arms, feet and fingers are always always deformed in that they cannot bend properly, and may be below the normal size. Because of the skin condition, it easily cracks causing an increased risk of bacterial infection. This disease is associated with a mutation in the gene for the protein ABCA12. This protein is called ATP-binding cassette transporter 12. This protein is essential for normal development of the skin. It is thought to be important for transporting lipids in cells that make up the epidermis of the skin.

Here are a few more brief genetic accidents that I came across:

Frog-like baby: In 2006, a baby was born that was neck-less. The head was almost totally sunk into the upper part of the body. Also, the eyeballs were extremely large and literally popping out of the eye-sockets. Unfortunately, the baby died within a half hour after birth.

13-inch tailed man: from a congenital defect, this man has a tail. It is located in the coccygeal end of the vertebral column, and he would not survive without it.

Cyclop Baby: In 2006, this baby was born with one eye. The medical staff believe that it was due to an experimental anti-cancer drug or from a chromosomal disorder known as cyclopia. The baby was born with a one eye in the center of her forehead, with no nose, and her brain was fused into one hemisphere. The baby was able to survive for a few days, but then, unfortunately, pasted away.

Feet facing backwards: A women in China was born with her feet facing the wrong way.

Baby with Three Arms: In 2006, a baby was born with a third arm. The arm was successfully removed, but the baby will need a long-term physical therapy to gain function in the remaining hand. That hand has no palm and flexes in either direction.

Nipple on the foot: A 22-year old women sought medical care to get a well-formed nipple surrounded by areola and hair removed from her the plantar region of her foot. Microscopic examination of the dermis showed hair follicles, eccrine glands, and sebaceous glands, alone with fat tissue on the base.

With all of these abnormalities, I am curious as to if we will ever find answers to why these happen. I am sure with how much we have discovered so far that eventually we will have out answers. However, the conditions seem so complicated that it will most likely take years and years to get to a conclusion.

(http://www.oddee.com/item_92015.aspx)

Development of Bipolar Disorder

2013-02-08T16:51:52Z

Bipolar is a highly inheritable disorder with an 80% chance of inheritance (Craddock, 1999). There has not been a single gene found that is the cause of this disorder. It is thought that several genes are involved and each raise the risk of onset. Some associated genes include: catechol-O-methyltransferase (COMT), GRK-3-BETA, monoamine oxidase (MAOA), G72/G30 gene, and the serotonin transporter gene. Most studies done need replication because they are usually family based studies. Certain families show certain genes affected, but as far as what genes are for sure involved still needs to be determined. Environmental factors also effect the onset of this disorder, which makes finding the cause much more difficult.

Cytokines are proteins that indicate internal responses to environmental stressors by promoting the inflammatory response. Cytokines have shown that they cause neuronal and glial apoptosis. Therefore, high levels of stress as a child produces high levels of cytokines and can be an important mediator in bipolar development.

During normal brain development, pruning of gray matter occurs as the brain matures. According to Gogtay's team, children with bipolar disorder have a more complicated pattern of gray matter in areas of the left hemisphere, losses in the right hemisphere, and losses in the mood regulation area in the mid-front part of the brain.

Gogtay N, Ordonez A, Herman DH, Hayashi KM, Greenstein D, Vaituzis C, Lenane M, Clasen L, Sharp W, Giedd JN, Jung D, Nugent Iii TF, Toga AW, Leibenluft E, Thompson PM, Rapoport JL. Dynamic mapping of cortical development before and after the onset of pediatric bipolar illness. J Child Psychol Psychiatry. 2007 Sep;48(9):852-62. PMID: 17714370

Craddock N, Jones I. Genetics of bipolar disorder. J Med Genet
1999;36:585-594.

Roybal, D.J., Singh, M.K., Cosgrove, V.E., Howe, M., Kelley, R., Barnea-Goraly, N., Chang, K.D. 2012. Biological evidence for a neurodevelopmental model of pediatric bipolar disorder. Isr J Psychiatry Relat Sci. (49(1): 28-43.

Heart Development

2013-02-02T03:24:00Z

At the onset of heart formation, we have six aortic arches instead of three. Supposively the three that we lose were from our evolutionary history. The three arches to go away during development are arches one, two and five. In the first five stages of cardiac development the heart is a tube that has four bulges. The tube forms by the fusion of lateral plate mesoderm from two distinct cardiac fields. The heart then forms an "s" shape by factors that develops into the heart structure that we are more familiar with. One bulge is called the bulbus cordis (truncus arteriosis). This bulge continues on to form a ventricle. Another bulge called the primitive ventricle becomes the other ventricle chamber. The last two bulges are the sinus venosus and primitive atrium. The sinus venosus becomes incorporated into the wall of the right atrium, and the primitive atrium becomes the two atria. The factors that cause the "s" shape cause the heart to loop and this causes the structures that need to be posterior to move to their location, and the structures that need to be anterior move to the anterior.

Starfish

2013-01-25T03:24:58Z

Today I went into lab to look at some slides under the microscope and take pictures. This is probably my favorite picture. I think starfish in general are interesting, so it was fun to be able to look at one under the microscope. I did some search on interesting facts about starfish and this is what I found.

-If a starfish is chopped into pieces, each piece can grow a whole new starfish (reproduce asexually).
-Starfish do not have eyes, but can sense light and shapes through the tip of their arms called an eyespot.
-The female starfish can produce a million eggs at one time.
-Fertilization takes place outside the body
-If an arm is lost, they can regrow it
-They have two stomachs: cardiac stomach and pyloric stomach
-They can change their gender whenever they want

That would be pretty useful if humans could grow back limbs if they were lost. Maybe someone will do some research on that to see how starfish do that, and if it is possible for humans to get that ability! (research would need to be ethical though!)

Below, I have the websites of the places where I found my information:
http://bestfunfacts.com/starfish.html
http://www.brighthub.com/environment/science-environmental/articles/117491.aspx
http://www.buzzle.com/articles/interesting-facts-about-starfish.html

Head to heart: trans of skeletal muscle stem cell for cardiac regeneration by Daughters

2013-01-17T04:14:16Z

A biology candidate, Daughters, presented on his previous research today in the science auditorium here at UMM. I thought that this was a good topic because he mentioned in his introduction that in order to understand stem cells, it is important to know a lot about developmental biology. From the early stages of cells, they have to 'decide' what path to take. Humans start out at one cell, and then differential into many, and those cells either because muscle cells or many other types of cells. Daughters mentioned that there are a little more than 200 different types of cells in the human body.

Daughters did his study on mice. He said that where the muscles come from early in development is important on how they react as an adult. All different types of locations of muscles express certain transcription factors that differentiate them from the others. For example, the eye muscle cells express certain transcription factors, while skeletal muscles cells express different transcription factors. Once in their set location, they then all express the same transcription factors, which differentiates them as muscle cells and not skin cells.

Daughters found that heart muscle cells are in a similar location to the jaw muscle cells during early development. He called this the 'cardio-craniofacial field'. Both types of muscle cells express different pathways to get to where they need to be. He found that BMP4 inhibits differentiation into skeletal muscle cells. This enables the skeletal muscle cell to become a heart muscle cell, like a normal one would.

The one thing that I got from this lecture was how amazing it was that he was able to produce heart muscle cells, and that they were able to 'beat'. He has a very good video, showing the heart muscle cells contracting and releasing.