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Monthly Archives: March 2014

Undead Mathematics

ImageMultiple Zombies, the second installment of the undead mathematics series is now available at the iTunes Book store. Get this book and the first installment, In Parts:Fractional Zombies, free for a limited time.

Both books are written for an audience of about 2-3rd grade. Multiple Zombies is specifically for those learning multiplication of numbers 0-10. As such, it introduces the concept of multiplication as addition of sets and includes practice problems tied to the evolving story. Each book requires an iOS or Mac device running iBooks to read and follows the story of two friends as they battle their way through a town suffering from a nasty case of zombies.

 

 

 
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Posted by on March 9, 2014 in Uncategorized

 

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BLyS Sequence Analysis

I’ve been playing with some sequence analysis and phylogentic tree construction programs recently because I would like to introduce these sorts of data analysis into my biology classes. As a sample protein, I decided to use BLyS / BAFF, a protein important in regulating B Cell numbers. I’ve always wondered about the origin of this kind of molecule, since working on it in grad school, and this seemed like a decent way to get some ideas about where it might come from.

The first thing I did was go to the NIH’s National Library of Medicine website: http://www.ncbi.nlm.nih.gov

It’s easy to search for any protein / gene / whole genome you are interested in examining. Knowing that BLyS is vital in humans and mice, I chose to start with the human sequence. I retrieved it as the following:

>gi|20196464|dbj|BAB90856.1| BLyS [Homo sapiens]
MDDSTEREQSRLTSCLKKREEMKLKECVSILPRKESPSVRSSKDGKLLAATLLLALLSCCLTVVSFYQVA
ALQGDLASLRAELQGHHAEKLPAGAGAPKAGLEEAPAVTAGLKIFEPPAPGEGNSSQNSRNKRAV

The easiest tool to find similar proteins in other animals is the Basic Local Alignment Search Tool for proteins, or BLASTp. Just using default settings, I pasted the sequence in the search field and hit go. (note, I actually just used the accession number, not the whole sequence)

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This retrieved tons of proteins with similar sequences from the vast database of sequence information, from which I chose several model species. One thing I wanted to do was to include several primates as a sort of internal calibration (assuming that they would all have very similar sequences compared to more distantly related species). I also wanted to get a few animals’ sequences who are quite distantly related to humans (frog and ground tit fir that bill)

Once I had a list, I put them all into a single text file and then used that in a second program. This time, I decided that the best ‘multiple alignment tool’ would be CLUSTALX. It’s been around for a while and can create data in a number of different forms. Besides, it’s free and versions are available for both mac and PC.

Again, for starters, I just accepted the default parameters and did a quick alignment:

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Obviously, there’s something odd about the canid familiars (dog) sequence, but before I did anything about that, I just wanted to see what a phylogenetic tree looked like. This is another thing that Clustal does well, it will export your sequence alignment as tree data in a number of formats, then I could plug that data into one final program. This last is a web based program that I access through a french site (but you can probably find it in a number of places). The program is called DRAWGRAM. It accepts alignment data and outputs a graphical tree representation of the alignment.

This is an important logical step… What I’m doing is asking for a family tree of sorts to be displayed that represents the relationship of the sequences I provided. We might want to assume that this also tells us how related the organisms that have these proteins are – and that’s not wrong, but it’s also not thorough as we’re only using ONE protein to make that assumption.

Here’s my first tree:

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Note how isolated Canis is on this representation.

Finally, I went back and truncated the Canis sequence to a place where I suspect the protein actually starts – my sequence from the NCBI gave me a string of Amino Acids at the front of the protein that I think are probably not there, but just got added by some computer algorithm without proper human oversight.

Once I did that Canis (by the way, I remained the sequence ‘DOG’ so I was sure it was the new one) fell in line with a sequence more similar to that seen in cats (felis):

ImageThat’s it for now. Although I expect that I will dig a little deeper with more animals to see if I can come closer to an ‘original BLyS’.

 References:

  1. Dereeper A., Audic S., Claverie J.M., Blanc G. BLAST-EXPLORER helps you building datasets for phylogenetic analysis. BMC Evol Biol. 2010 Jan 12;10:8. (PubMed)
  2. Dereeper A.*, Guignon V.*, Blanc G., Audic S., Buffet S., Chevenet F., Dufayard J.F., Guindon S., Lefort V., Lescot M., Claverie J.M., Gascuel O. Phylogeny.fr: robust phylogenetic analysis for the non-specialist. Nucleic Acids Res. 2008 Jul 1;36(Web Server issue):W465-9. Epub 2008 Apr 19. (PubMed) *: joint first authors
  3. Felsenstein J. PHYLIP – Phylogeny Inference Package (Version 3.2). 1989, Cladistics 5: 164-166
  4. Larkin,M.A., Blackshields, G., Brown, N.P., Chenna, R., McGettigan, P.A., McWilliam, H., Valentin, F., Wallace, I.M., Wilm, A., Lopez, R., Thompson, J.D., Gibson, T.J., Higgins, D.G. (2007) Clustal W and Clustal X version 2.0. Bioinformatics, 23:2947-2948.
  5. Thompson,J.D., Gibson,T.J., Plewniak,F., Jeanmougin,F. and Higgins,D.G. (1997) The ClustalX windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Research, 25:4876-4882.
 
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Posted by on March 7, 2014 in Uncategorized

 

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Evolution Animated

I just stumbled upon this cartoon for the first time today and I’m totally blown away. Sure, there are some things that could be explained better. There are a couple of moments when the illustrations could be a bit more accurate. But, overall, it’s a very good summary of the basic elements of evolution and pretty funny. (I wish I had made this!)

Have a watch and enjoy.

also, check out Kurzgesagt’s other animations on the Big Bang Theory, et al.

 
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Posted by on March 6, 2014 in Uncategorized

 

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Playing with sequence data

I’ve been playing with sequence data a lot recently. It’s been so long since I have done any real work with this stuff that I’ve fallen behind in my knowledge of the tools for analyzing the data. 

I hope to post a couple of things here after I have been working on as a sort of tutorial on how to use ClustalX as an alignment tool that (I think) can even build phylogenetic trees from homology data.

 
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Posted by on March 5, 2014 in Uncategorized

 

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Aside

The snail gets up
And goes to bed
With very little fuss

 -Kobayashi Issa (1763– 1828)

 
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Posted by on March 4, 2014 in Uncategorized

 

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