Soap Bubbles and Cellular Spacial Organization

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Hello all,

Considering that the vertebrate embryology lab was a pseudo-failure (some primitive streaks and blood island were observed, but not much else), we decided to do a lab about cellular organization. Specifically, developing cells organize themselves to maximize stability and shared membrane surface area in the developing embryo. These trends can also be observed in soap bubble formation, treating the bubbles as analogous models for individual developing cells. Interestingly, there has been an extensive amount of scientific literature written about this idea, fueled by the interest into the mathematical modeling of the biological world.

Here are some images of soap bubbles I took in the lab:

SoapBubble1.jpg
Note the patterns of how the bubbles touch, seemingly maximizing surface area.

SoapBubble2.jpg

For comparison, here is a link to an image that shows bubble patterns compared to actual developing cells:

http://www.drosophila-images.org/images-2005/01-slide-F.htm

Time Lapse Lab (A Lesson in Patience)

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Hello all,

So after 3 weeks of working at a lab to record some of the developmental stages of the fruit fly through time lapse photography, I am mostly empty handed. However, even though the process was extremely time consuming (for very little results), I actually learned a lot. Besides becoming more familiar with the microscopy equipment, I found qualitative observation of the flies very interesting! Their behavior, especially during mate attraction, is quite a spectacle. While it would have been nice to get some really neat videos, I feel that I was able to appreciate to main purpose of this lab: to learn more about fly development, to find innovative and unique ways to observe those flies (some other students and I crafted a camera stand to better observe the flies' behavior in focus), and to experience first hand the incredible frustrations of working with time lapse imaging (and being at the will of some stubborn invertebrates).

All in all, here is one of my many "failed" attempts at catching a fly emerging from its pupa. While the video doesn't show much, it's still pretty cool to notice the fly's eyes and hair-like structures though the pupa. Very cool stuff!

Link: http://www.youtube.com/watch?v=1pe8SaEHJZw&feature=youtu.be

Wish me better luck on the vertebrate embryology lab (Chickens, here I come!).


Crouzon Syndrome

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Hello all,

Considering the discussion we had in class about vertebrate embryology, I was compelled to draw a loose parallel between this course and my Evolution class. In Evolution, we were discussing various adaptations and how they were either related to selective pressures or not, noting that some features are not always a result of natural selection (as the adaptationist theory would say). Within this discussion, various developmental features were referenced, among them the branchial arches of a developing vertebrate embryo. Specifically references was a disorder known as Crouzon syndrome.

Crouzon syndrome is a significant malformation of the face and surrounding bone structure as a result of early developmental issues. These problems originate from the branchial arches not fusing properly, and thus create widespread facial disfigurations.

Some may know that a failure to properly fuse branchial arches is the same issue that can cause a cleft pallet, which is a much more common defect. This is an incredibly interesting concept in development; the same stages and structures in the developing embryo can result in drastically divergent problems based only in small differences in initialization.

Here is the wikipedia page on Crouzon syndrome:

http://en.wikipedia.org/wiki/Crouzon_syndrome

Neurogenesis and Neuronal Development

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Hello all,

I feel bad that I have not been keeping up with my weekly blog posts in the past few weeks, but to be honest, with all I have to do my weekly posts have sunk significantly lower on my priority lists. Not to worry, however, as I will be making up for that with numerous blog posts in the coming weeks.

This week, I would like to reference a blog post written by a classmate of mine about how BPA can affect neuron development through a Kcc2 dependent mechanism. I found this topic particularly interesting because I am presenting on a topic for my senior seminar that is also concerned with neuronal development.

Specifically, my presentation will talk about adult hippocampal neurogenesis (or the growth of new neurons in the dentate gyrus region of the hippocampus, also known as AHN) and how that process can help us to regulate stress. As chronic stress is such a commonly co-morbid affliction with major depressive disorder (MDD), I will also briefly reference how chronic stress can halt neurogenesis within the context of MDD, and how antidepressants can actually reverse this process.

This is an especially interesting topic as it suggests novel cellular pathways for the function of antidepressants in the treatment of depression, a topic that is strangely mysterious to scientists on a deeper neurological level. I was excited to see that other students were thinking about ways that neuronal development may be affected by outside environmental factors, such as BPA. It is truly shocking to examine how any given protein or gene may have numerous functions within the cell depending on other pathways around it, which leads me to wonder how environmental factors can contribute to the inhibition of AHN in addition to chronic stress and depression. Does this affect the efficacy of various antidepressant pathways? Does exposure to certain chemicals earlier in development (i.e. in utero or as a young child) affect AHN or a predisposition to chronic stress/MDD?

I have no idea, but these sure are some interesting questions, and hopefully ones that researchers can examine to improve treatment (and possible prevention) of disorders like MDD and chronic stress.

Week 5: More Lab Images!

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Hello all,

I deeply apologize to anyone that has been diligently following my blog (which, in reality, in probably no one) as I have not posted in about 2 weeks not. However, my lack of an internet presence does not mean I have been neglecting my lab and classroom studies! I have indeed been researching more and more in the lab and practicing more with the microscope, further developing my skills. In lab, we had an assignment to find and investigate a structure that we found particularly interesting and document its development through a multiple image portfolio.

This assignment is 100% representative of why I enjoy this lab so much: no pointless busywork, just development of one's own skills and interests. One of the reasons I took this class in the first place is that it is an excellent compliment to other courses I've taken, both in the Psychology and Biology majors. For example, I love Biological Psychology, but this course tells a completely different story from the perspective of development, rather than the interaction of fully developed adult brain structures. Because of this inherent interest I possess in BioPsych, I felt that documenting the development of the spinal cord and surrounding neurological tissue (i.e. the ventral and dorsal spinal nerves) to be a fitting choice for my assignment.

Here are a few images I took in lab. I found the development of the spinal nerves and the increased organization of the cells in the spinal ganglia to be especially cool to observe!
Note that I have also spent some time annotating some of the images to make various structure more clear when comparing different developmental stages. Here are just a few of the images from my portfolio:


Here is an image of the spinal cord earlier in development before the spinal nerves have really developed. Scale Bar = 25┬Ám:
ANNO Pig Spinal Cord 5x (Slide 12d).tif


Still early in development here, but a closer magnification. Isn't it cool how you can see the individual cells!?:
ANNO Pig Spinal Cord 10x (Slide 9e).tif


Later in development, spinal nerves much more visible now. Most structures more defined and organized:
ANNO Pig Spinal Cord 10x (Slide 12d).tif

Week 4: Sean B. Carroll

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This week's entry is inspired by the difficulties of the US postal service to deliver packages on time!

Let me back up... for my developmental biology course, we were assigned to read a book about the nature of development. This book does supposedly does an excellent job at capturing the wonder of embryonic development without sacrificing the science behind it. This text, Endless Forms Most Beautiful, by Sean B. Carroll is a great supplement to any textbook in a developmental class, resulting in a more well-rounded view of embryology.

Unfortunately, I ordered this book online, and the order has been delayed. Hopefully it will arrive soon, as we are having discussions in class in which I feel disadvantaged. However, not having the text in-hand is no reason to declare defeat! I thought it would be appropriate to write a blog entry examining the author of this book, so that when the book did arrive, I could read it with a little bit on context under my belt.

Dr. Carroll seems to be a man of many interests in Biology, while remaining rooted in fundamental "micro-scale" research. He is a professor of Molecular Biology, as well as Genetics at the University of Wisconsin, which is a refreshing fact considering that many non-environmental scientists often lack a novelistic literary sense (speaking generally of course).

Having written multiple texts for the classroom, Carroll seeks to truly integrate the ideas of evolution and development. At times it is easy to lose sight of the overall context when pouring over embryonic microscopy slides, or perhaps to forget about genetic regulation and expression when considering a common ancestor among humans and apes. Without the coupling of these fields (along with ecology, in my opinion) conclusions drawn from either field individually are rather stunted, and can have little implication. I can truly appreciate the value in a biological text that looks at the "big picture" while still harkening back to the smaller elements, such as transcription factors and intricate gene expression.

While I have not yet read any of his work, I am sure that I will very much enjoy Carroll's interpretation of developmental biology.

Here is a link to a web page about Dr. Carroll, detailing some of the more specific facets of his research, academic involvements, and literary contributions.

seanbcarroll.com

Week 3: Dpp and Morphogen Gradient Formation

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Week 3 already?! It's hard to believe my last semester is passing me by so quickly!

One of the in-class assignments for my developmental biology class this past week was to read an article on positional information and how that information is perceived by the cells in the developing embryo to result in polarity, directional migration, and differentiation. The article spoke about the "French Flag" model for morphogen (extracellular agents that help to determine cell development) gradient formation, described in detail by Lewis Wolpert. This model is important representation of how a gradient can differentiate developing cells, but it certainly cannot be the entire story behind cellular positional information, as the article goes on to discuss (intercellular communication and regulation must also be at play).

A few specific examples of morphogens were provided, along with their typically understood function as they act in the developing embryo. Among them was the well-know (at least to developmental biologists) Dpp molecule. Decapentaplegic, or Dpp, is a morphogen that plays central roles in the development of the fruit fly embryo, specifically helping to differentiate the various imaginal discs (for example, wing disc) of the embryo, which later develop to form organs and limbs. Because this molecule is so important within embryology and has such widespread effects, I was curious about the details of its functionality. While the Wolpert et al. article talked a lot about mechanisms other then morphogens, I was more intrigued by the sensitive intricacies of a small concentration extracellular gradient possessing such omnipotence!

In my search for more information, I ran across a recent article by Zhou et al. seeking to understand more (among other things) about Dpp gradient formation. The authors point out that this is a difficult task, considering that gradients are usually present at extremely low concentration magnitudes, which can elicit confounding results from otherwise sound experimental procedure.

Without delving too deeply into the results of the paper, the authors suggest that Dpp gradient formation occurs firstly by simply diffusion, followed by a more complex process of cellular uptake and degradation, which helps to regulate the sensitive levels of Dpp in the extracellular matrix. It is this uptake process that pervious studies have failed to fully grasp, skewing previously accepted results about gradient formation.

A last comment provided by the authors urges us to recall that even if we understand how one morphogen functions, embryo development is a delicate symphony composed of entire suites of molecules, all in varying amounts and conformations. Each of these has a specific function, which can be altered by the presence and concentration of other morphogens. Understanding embryology from a single gradient is synonymous to extrapolating a comprehensive knowledge of the entire human brain from a single region. Cellular/molecular interplay and complex feedback pathway mapping is the name of the game here folks! So don't worry, there's a lot more science to be done!

Here are the articles to which I was referring throughout my entry:

Wolpert and Kerszberg (Positional Information).pdf

Zhou et al. (Extracellular Diffusion).pdf

Note: I am not claiming any rights to these articles by posting them. All copyright information can be found in the articles for the appropriate authors and publishers.

Week 2: Microscopy Images

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Hello all,

Throughout this last week, I spent a considerable amount of time in the lab learning how to use the Leica DMLB research microscope to examine various biological specimens. While many of the photos I took were under lower magnification, this scope's abilities really come into play under detailed 40x magnification. Additionally, images can be given more contrast and detail using a technique known as DIC imaging. Using various beams of interfering light to illuminate structures that might otherwise be invisible under normal bright field microscopy. When used correctly, this technique produces stunning images!

Unfortunately, there were some complications that prevented me from using this method to its full extent. While powerful, this microscope is also a sensitive instrument. An important component of the scope, called the condenser, was malfunctioning due to misuse by the time I was able to gain access to the lab. While this was a setback, I feel that I gained a greater appreciation for how the scope functions, the concepts behind DIC microscopy, and the intricate and beautiful nature of a wide variety of biological specimens.

Here are a few of the images I took while in the lab. Note: I attempted to add in a scale bar to the images using an online program, but the results were poor. Thus, I am showing these images with no scale bar, but with some visual editing for contrast, brightness levels, etc.

Cheek cells (10x Magnification).jpg

Above is a slide of some of my cheek cells, at 10x magnification.

Starfish larva (5x Magnification).jpg

Here is a slide of a species of starfish, specifically the larva. This image is at 5x magnification.

Drosophila (5x Magnification).jpg

A familiar face for geneticists and developmental biologist alike, the above image is of a common fruit fly, of the genus Drosophila. The head, mouth, and forearms are depicted here at 5x magnification.

Ancylostoma caninum (5x Magnification).jpg

Lastly, here is an image of a nematode worm, Ancylostoma caninum. Specifically, the head/mouth is depicted here. I personally enjoy this image as many intricate details of the worm's anatomy is shown. This image was taken at 5x magnification.

Week 1: Embryonic Stem Cells

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For this first entry, I decided (for a variety of reasons) that it would be appropriate to cover the basics of embryonic stem cells. Firstly, stem cell research is at the forefront of the developmental field, and has incredible applications in many areas of biology and medicine.

Secondly, I confess that while stem cells have always been a hot issue in popular science, I know very little about their applications in research. I decided to look up a few preliminary sources to orient myself to the concept of stems cells, both from a cellular and utilitarian perspective.

It was interesting to be able to tie the information I found into concepts learned in other courses. For example, much of embryology centers around gene expression and regulation. The activation or suppression of certain genes during development is in large what dictates normal progression through the developmental process. Furthermore, interruption of these normal regulatory processes can result in strange effects. However, it is the examination of these regulatory mechanisms that will lead us to further advancements to possibly eliminate many developmental defects.

Specifically, I found it interesting that so many of the same cellular signaling pathways involved in development are also found in the suppression of cancer. However, when I thought about these similarities a little more, the commonalities made perfect sense. If you understand cancer to be an over-proliferation of cells due to broken cellular regulation (among other factors), embryology is essentially the intended proliferation of cells to form the organs and tissue of a developing organism. This concept greatly intrigues me, noting that a subset of cellular mechanisms have the power to both create the beginnings of all life, as well as propagate one of the most deadly and rampant disease we know today, cancer. It is the similarities between these various facets of biology that continue to drive research and create new solutions to previously insurmountable problems.

In the coming entries of this blog, I will be discussing both weekly concepts, as well as other topics in developmental and evolutionary biology that I find interesting or novel. Additionally, I may post images from lab work on this blog. Stay tuned for more!

Lastly, I have included a link to some preliminary material on stem cells, what they are, and their various applications.

http://www.news-medical.net/health/What-are-Embryonic-Stem-Cells.aspx