Soap Bubble interactions

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For lab this week we placed soap bubbles into petri dishes to visualize their physical interactions when placed closely together. The interactions observed mimic the interactions between cells in developing embryos, suggesting that embryo shape is to some degree based on physical forces and not entirely dependent on chemical factors.

image with two bubbles:
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three bubbles in a row:
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three bubbles in a cluster:
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four bubble cluster:
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five bubble cluster:
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These images were all obtained by blowing individual bubbles onto the petri dish and gently pushing them together. The greatest difficulties involved getting the bubbles to be approximately the same size and getting them to last long enough to photograph.

nine bubble cluster:
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For this image, placed one larger bubble on the dish and manually split it with the edge of a bubble blower. this technique was more prone to failure but when successful was capable of producing larger bubble clusters than would be possible to achieve through manual blowing.

lastly, for fun i created the "Super Bubble":
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Drosophila larvae video

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These are a pair of videos that i shot of Drosophila larvae moving about on an agar plate. The videos were intended to be in real time but due to my lack of understanding as to how the recording software functions the result is a compressed timelapse that conveys the illusion that the larvae are moving at incredible speeds. Despite this, I think that the video turned out rather well image-quality wise as the movement and feeding patterns of the larvae are clearly visible to the observer.


Cis Regulation of Creative Dance Performance

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Recently an assignment for class had us read Gregory Wray's paper on the evolutionary significance of cis-regulatory elements. In this paper Wray cites another paper that makes the somewhat dubious claim that creative dance performance in humans is regulated by a cis-element mutation. Struck by the oddity of this claim I tracked down the original paper by Bachner-Melman et. al. to determine the validity of this statement. The paper begins by citing similar research into the effects of genetics on athletic ability and musical aptitude as examples of research into what they believe to be major elements of creative dance. They also compare dance to other behavioral phenotypes shown to have some level of genetic inheritance such as schizophrenia and attention deficit disorder. Bachner-Melman et. al. then identify two genes, AVPR1a and SLC6A4, that they believe have an effect on creative dance performance. After stating their case for why their research is valid Bachner-Melman et. al. move on the the results of their research, which is where things get a little sketchy. The researchers claim that significant differences in allele frequencies of the two genes in question exist between dancers and non-dancers, I was unable to determine where in their results this was determined. This may not be significant as I may simply lack the ability to understand their results, but it personally makes me question their conclusions. This illustrates the importance of looking into dubious claims and remaining skeptical when reading about scientific discoveries.

Sources:
Wray, G. A. 2007. The Evolutionary Significance of Cis-Regulatory Mutations. Nature Rev. Gen. 8: 206-216

Bachner-Melman, R., Dina, C., Zohar, A. H., Constantini, N., Lerer, E., Hoch, S., Sella, S., Nemanov, L., Gritsenko, I., Lichtenberg, P., Granot, R., Ebstein, R. P. 2005. AVPR1a and SLC6A4 Gene Polymorphisms Are Associated with Creative Dance Performance. PLoS Gen. 1(3): e42.

Effects of BPA on Neurodevelopment

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After reading this excellent blog post on the effects that Bisphenol-A (BPA) can have on neurological development i became interested in finding what problems exposure to this chemical can cause and how it is regulated by the FDA. A panel conducted by the National Institutes of Health in 2007 determined that there is some concern for the effects of BPA on the neural development for fetuses and young children but decided that BPA is of negligible concern to adults. the FDA has banned the use of BPA in the manufacture of baby bottles but has not banned it from being used in food packaging even in the case of baby food and formula despite protests from several interst groups. The paper mentioned in Heidi's blogpost was published only a couple of weeks ago so it will be interesting to see what impact it has on this debate.

Gynandromorphy

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Gynandromorphy is a condition caused by an unequal distribution of sex determining chromosomes in early mitotic division. this can lead to a scenario where some of the cells in an organism are male and some are female. if this condition occurs early enough in embryonic development it is possible for an organism to be divided bilaterally into male and female halves. this condition is most often observed in insects but has also been seen in birds and crustaceans.

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Gynandromorphic cardinal. image source http://whyevolutionistrue.wordpress.com/2012/09/04/a-gynandromorph-cardinal-one-half-male-the-other-half-female/

Cyclopia

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During prenatal development, brain abnormalities or exposure to certain chemicals can result in an embryo developing a single, centralized eye. The brain is usually significantly reduced in size and the nose is usually absent or replaced with a non-functioning proboscis. This is a lethal mutation with most sufferers surviving for only minutes after birth, often due to difficulties breathing due to a lack of nostrils.

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Source: Garzozi, H. J., Barkay, S. 1985. Cause of True Cyclopia. British J. of Ophthalmology. 69: 307-311

Quadruplex DNA Found in Human Cells

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A team of researchers at Cambridge has discovered the presence of G-quadruplex DNA in human cells using antibody-specific binding. The G- quadruplex forms when DNA is rich in guanine and is highly thermodynamically stable, which explains how it can occur in vivo. Quadruplex DNA is observed most often during S phase after DNA has replicated. This structure has been previously observed in ciliates, but never before in mammals.

Source: Biffi G, Tannahill D, McCafferty J, Balasubramanian S 2013. Quantitative visualization of DNA G-quadruplex structures in human cells. Nat Chem advance online publication. doi: http://www.nature.com/nchem/journal/vaop/ncurrent/abs/nchem.1548.html#supplementary-information

Recent Comments

  • delbu002: Gynandromorphy does not always occur with bilateral symmetry and can read more
  • delbu002: The bird in this picture is not hermaphroditic as it read more
  • walsh414: It appears as though the gynandromorphy occurs with bilateral symmetry. read more
  • voldrani@gmail.com: This is a really interesting phenomenon, and a great picture! read more
  • Heidi: This is really interesting! So this bird shown in the read more

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