BIOL200 2013: Difference between revisions

Revision as of 16:18, 4 March 2013

EXPERIMENT # 4

BIOL 200 Cell Biology II LAB, Spring 2013

Hunter College of the City University of New York

Course information

Instructors: TBD

Class Hours: Room TBD HN; TBD

Office Hours: Room 830 HN; Thursdays 2-4pm or by appointment

Contact information:

Dr. Weigang Qiu: weigang@genectr.hunter.cuny.edu, 1-212-772-5296

Experiment #4

The Tree of Life and Molecular Identification of Microorganisms

Objective

To classify microorganisms and determine their relatedness using molecular sequences.

LAB REPORT GRADING GUIDE

CELL BIO II Experiment #4:

Introduction 1 point :

 Statement of objectives or aims of the experiment in the student’s own words.
 (not to be copied from the Lab Manual)

MATERIALS AND METHODS 0 points :

 This should be a brief synopsis and must include any changes or deviations 
 from the procedures outlined in the Lab Manual. Specify which organisms were 
 used to create the phylogram.

RESULTS 4 points :

 A print out of the phylogram will suffice.

DISCUSSION 4 points :

 Responses to discussion questions.

SUMMARY |CONCLUSION 1 point :

 Two sentence summary of your findings.

REFERENCES 1 point :

 Credit is given for pertinent references obtained from sources other than the Lab Manual.
 This point is in addition to the 10 for the lab report..

INTRODUCTION

Introduction
Evolution can be defined as descent with modification. In other words, changes in the nucleotide sequence of an organsim’s genomic DNA is inherited by the next generation. According to this, all organisms are related through descent from an ancestor that lived in the distant past. Since that time, about 4 billion years ago, life has undergone an extensive process of change as new kinds of organisms arose from other kinds existing in the past. The evolutionary history of a group is called a phylogeny, and can be represented by a phylogram (Figure 1). A major goal of evolutionary analysis is to understand this history. We do not have direct knowledge of the path of evolution, as by definition, extinct organisms no longer exist. Therefore, phylogeny must be inferred indirectly. Originally, evolutionary analysis was based upon the organisms’ morphology and metabolism. This is the basis for the Linnaean classification scheme (the “Five Kingdoms” scheme). However, this method can lead to mistaken relationships. Different species living in the same environment may have similar morphologies in order to deal with specific environmental factors. Thus these similarities have nothing to do with how related the organisms are, but are a direct result of shared surroundings. However, with the advent of genomics, organisms can be grouped based upon their sequence relatedness. Since evolution is a process of inherited nucleotide change, analyzing DNA sequence differences allows for the reconstruction of a better phylogenetic history.
File:TreeLife.png Tree of life based on 16S ribosomal RNA (image credit: NR Pace, Science 1997).
Of course, when comparing DNA sequences, the question of which genes to use arises. The most widely used genes are those coding for the 16S rRNA gene in prokaryotes and the 18S rRNA gene in eukaryotes. These genes code for small subunit ribosomal RNA and are used for evolutionary analysis because they 1) are found in all organisms, 2) are functionally conserved, 3) vary only slightly between organisms (their nucleotide sequence changed slowly throughout evolution), and 4) have adequate length. In this lab, you will be performing evolutionary analysis by constructing a phylogram of 15 microbes spanning bacteria, archaea and eukarya. You will find and download rRNA sequences, align them and use that alignment to create a phylogram.

MATERIALS

Required hardware: Computer

Examine Table I, select representative species from Bergey’s Manual. Select 2 prokaryotic species from each group, giving 14 prokaryotic species total. Also select the Eukaryotic representative, Saccharomyces cerevisiae.
Access the NCBI website: http://www.ncbi.nlm.nih.gov/
Under the “Search” category, select “Nucleotide”
Under the “for” category, type the accession number for your first organism, and hit the “Go” button. This takes you to the access for the 16S rRNA for your organism.
Download the 16S rRNA sequence for your first organisms by choosing “FASTA” under the “Display” category.
Copy and paste the entire output into a Microsoft Word file.
Edit the sequence id to match the format of “Genus_Species_Genbank#” (eg. > Escherichia_coli_174375).
Repeat process for all of your organisms, pasting the sequences into the same Microsoft Word file. (note: be sure to place a blank line between each sequence entry)
Access the EMBL CLUSTALW alignment website: http://www.ebi.ac.uk/Tools/clustalw/, and copy and paste your entire Microsoft Word file into the area which asks you to “Enter or paste a set of sequences in any supported format”. Click “Run”. This program will make an alignment of all of your sequences.
Click “Show as Phylogram Tree” to create a tree showing the relatedness of your organisms based on their 16S rRNA sequences.
To print your phylogram tree:
1. hit the “Print Screen” button on your keyboard
  
  open the Paint program from your “accessories” menu on your computer
  
  hit paste to paste your screen
  
  “select” your phylogram tree
  
  copy and paste it into a new paint file
  
  print your tree and email it to yourself

PROCEDURE
Problems (pg.31-32): 1.2, 1.3, 1.5,1.9, 1.10, 1.11

February 12

NO CLASS

(Read Chapter 6 for next class)

February 19

Yozen will not be lecturing

Chapter 6. Gene and Genome Structures [Lecture Slides Lecture Slides Ch.6-Che
Tutorial: ORF Prediction using GLIMMER
Homework: This homework will be graded.

Assignment #3
Bacterial gene identification using Glimmer Remember to first log in to mysql by doing: ssh mysql Copy the Lyme disease bacterium lp17 plasmid file "/data/yoda/b/student.accounts/bio425_2011/data/lp17.fas" into your home directory. Run long-orf, extract, build-icm, and glimmer3. Show your commands and "cat" the final output. Describe key elements of a prokaryotic gene in addition to the open reading frame. Textbook Questions (pg152-153): 6.6, 6.9, 6.15
Read All of Appendix 1.

February 26

Appendix 1. More PERL (Lecture Slides)
Homework

Assignment #4
Beginning Perl This time, both novices and experienced programmers do the same homework, with one small difference in the use of the program. Recall from the first class where I introduced the FASTA-format. In this format, sequence data is recorded as follows: >SequenceID_info1_info2 atgcgtgatg... Of course, the ID portion is itself not standardized, and the sequence can also be an amino acid sequence. For simplicity, let's assume that in the ID field, you have a "Strain" name followed by a "protein" name, separated by an underscore (_). You will write a program to read a FASTA file with the ID format described above, and a nucleotide sequence. For both novice-level and experienced level programmers, your program will: Pick out the strain name, the protein name, and the nucleotide sequence. Calculate he length of each sequence. Calculate the GC content (in percent) of each sequence. Calculate the percent composition of each nucleotide (base composition). Novice-level task: Your program will just print the above information for all sequences, in a readable form. Sample output could be: Strain: B31 Protein: ospA Seq Length: 819 GC content: 33.58% Base composition: A 42.98 %, T 23.44 %, C 14.77 %, G 18.80 % If your percentages have more than 2 decimal places, that's OK. Experienced-level task: The only difference from novices is that your program will ask the user for the name of a strain and protein, separated by an underscore (ie, B31_opsA). Once given that input, it will print the exact same output as above, but only for the sequence described by that input. If the input doesn't exist, it will say so and exit. Your program will continue to ask the user for the sequence ID until the user types 'quit' or they give an invalid sequence ID. You can do this by using a while loop. Notes Calculating the GC content and the base composition is easy if you make use of the tr (transliterate) function as described at the bottom of page 232, and divide the result by the sequence length. GC content is just the sum of total G and C nucleotides, divided by the sequence length. I do want percents, so remember to multiply the results by 100 and to append a '%' at the end. Getting the strain name and the protein name separately can be accomplished with the split() function (check new slides or search on the internet). You will test your program the with the file /data/yoda/b/student.accounts/bio425_2011/data/Borrelia_osp.dna.fasta as input. You don't have to include the file itself with your homework, but I do still want you to copy the program output and submit it with your assignment. Again, the program cannot use any outside dependencies/modules such as BioPerl (supposing you know how to use it.) Besides that, you can implement it however you like. If you know about references, it is possible to do this assignment without using them.

March 5

Chapter 2. Data Search and Alignments Lecture Slides Ch.2-Che
Object-Oriented PERL & BioPerl (Link to Bioperl site and HOWTOs)
Homework:

Assignment #5
BioPerl Assignment For this assignment, you will use the .predict file you made with glimmer in assignment 3. If connecting from home: open gedit before logging on to mysql. For BioPerl to work, you must log on to mysql. Complete the assignment by following these steps. Make sure each part works before trying to solve the next part: Make a perl script that reads each line from the .predict file that describes a gene (skip the heading line). Save each line (hint: array, anyone?) Now, in the same script, use Bio::SeqIO to read the lp17.fas file and get a Bio::Seq object. Go through each line saved from the .predict file. Remember: these are predicted orfs: For each of these, extract the start and stop positions and "strand" values (the three values following the orf name). If the strand starts with a '-', it means the orf is on the reverse complement, so you need to use the Bio::Seq method "revcom". Now, extract the orf sequence using the start & stop values using the Bio::Seq method "subseq", paying special attention to sequences on on the '-' strand. Print both the DNA sequence AND the protein sequence. See these sample scripts for how to use revcom and subseq: ../bio425_2011/sample-perl-scripts/revcom_translate_seq.pl ../bio425_2011/sample-perl-scripts/subseq.pl And I linked to the HOWTO above in case you forgot. Output should be informative: ORF: orf00002 DNA: ... Protein: ...
Read For next class, read CH 3

March 12

Chapter 3. Molecular Evolution Lecture Slides Ch.3-Che
Homework: (TBA)

March 19

REVIEW Session for MID-TERM EXAMS

March 26

MID-TERM

April 2

Chapter 4. Phylogenetics I. Distance Methods Lecture Slides Ch.4-Che
"Tree Thinking" Puzzles - (Download)
Tutorial: PROTDIST and NEIGHBOR using Mobyle Pasteur

Assignment #6
Chapter 4 Questions & Problems (pg.95-96): 4.1, 4.3, 4.4, 4.7, 4.8

April 9

Chapter 5. Phylogenetics II. Character-Based Methods Lecture Slides Ch.5-Che
Tutorial: DNAML and bootstrap analysis using Mobyle Pasteur

April 16

Topic: Relational Database and SQL
Tutorial: the Borrelia Genome Database
Homework: SQL-embedded PERL

Assignment #7
SQL-embedded PERL Continue work on the assignment we began in class. It is reproduced below, with some added functionality. Your script will: Retrieve TEN orfs from the orf table that belong to the strain Pko. Find and store the sequences described by those orfs and their lengths. Determine if the orf is on the reference or reverse complement strand, and use that information to print the correct sequence. Print the orf name, sequence, and the length for each orf. In addition to printing the above information to the screen, write out the sequence information (in FASTA format) to a file called "Pko_orfs.fasta". The sequence ID should be of the form: Pko_orfname Note that the above will require the use of BioPerl. For those looking for extra challenges, you can try adding the following: Ask the user for the strain and contig names that they want orfs from, and only retrieve those rows. This means you must find a way of obtaining their respective IDs from just their names. Make sure the sequence IDs are informative. They should look like this: strainname_contigname_orfname If asking users for input, fail if they gave a strain or contig name which does not exist in the database. Also if asking users for input, the output file's name should be changed to reflect the chosen strain. Ask the user the minimum length the orf is allowed to be, and only print orfs as long, or longer, than what the user specifies. Sample scripts will go up slowly, over time, including example SQL statements.
Questions from Text (pg.115-116): 5.1, 5.3

April 23

NO CLASSES (Spring recess)

April 30

Topic: Statistics
In-class exercise: R basics and short demonstration of a simple boxplot
Tutorial: Statistical Visualization using R Lecture Slides-Che

May 7

Chapter 6 (Gene Expression) & Chapter 8 (Proteomics)
Tutorial: Array Data Visualization and Analysis ( Micro-Array Analysis Slides)
Homework:Data Analysis using R

Assignment #8
Part 1 Data Analysis: For this assignment, you will use sample data to answer the question: Do men and women have different body temperatures? The file temps.txt located in ../bio425_2011/data on eniac, contains body temperature data for a sample of adults. Use a hypotheses test with α = .05 to answer the above question of interest. NOTE: For this part of the assignment you will need to turn in your answer to the question with p-values in addition to the R syntax used. Indicate your null hypothesis. Part 2 Gene Expression Data Analysis: Using the files GSM129276_cy3.txt & GSM129276_cy5.txt located in ./bio425_2011/data on eniac, conduct an analysis to produce a histogram of fold changes. In addition to the histogram, you will need to turn in the R syntax used in every step of the analysis in R, along with an explanation as to why the step was necessary.
Read For next class, read CH 7

May 14

Chapter 7. Protein Structure Prediction

May 21

Final Project Due (TBA)

Useful Links

Unix Tutorials

A very nice UNIX tutorial (you will only need up to, and including, tutorial 4).
FOSSWire's Unix/Linux command reference (PDF). Of use to you: "File commands", "SSH", "Searching" and "Shortcuts".

Perl Help

Professor Stewart Weiss has taught CSCI132, a UNIX and Perl class. His slides go into much greater detail and are an invaluable resource. They can be found on his course page here.
Perl documentation at perldoc.perl.org. Besides that, running the perldoc command before either a function (with the -f option ie, perldoc -f substr) or a perl module (ie, perldoc Bio::Seq) can get you similar results without having to leave the terminal.

Bioperl

BioPerl's HOWTOs page.
BioPerl-live developer documentation. (We use bioperl-live in class.)
Yozen's tutorial on installing bioperl-live on your own Mac OS X machine. (Let me know if there are any issues!).
A small table showing some methods for BioPerl modules with usage and return values.

SQL

SQL Primer, written by Yozen.

R Project

Install location and instructions for Windows
Install location and instructions for Mac OS X
For users of Ubuntu/Debian:

sudo apt-get install r-base-core

For users of Fedora/Red Hat:

su -
yum install R

Utilities

An RSS button extension for chrome. Can add feeds to Google Reader and others.
A similar extension which adds a "Live bookmarks"-like feature to Chrome (like Firefox's RSS bookmarks).

Other Resources

Information Theory Primer by Thomas D. Schneider. Useful in understanding sequence logo maps.

@@ Line 60: / Line 60: @@
 {| class="collapsible collapsed wikitable"
 |- style="background-color:lightsteelblue;"
-! Assignment #2
+! PROCEDURE
 |- style="background-color:powderblue;"
-| '''Before you begin...'''<br />
-Do this ONLY ONCE: <pre>echo "source /data/yoda/b/student.accounts/bio425_2011/bio425.profile" >> ~/.bash_profile</pre>
-Alternatively, you can open ~/.bash_profile in a text editor (ask me if don't know how) and paste the line: <pre>source /data/yoda/b/student.accounts/bio425_2011/bio425.profile</pre> at the end.
-|-style="background-color:powderblue;"
-| '''Beginning Perl'''<br />
-For the homework, read up to page 221 in Appendix 1. For February 26, read all of Appendix 1.
-There are '''two choices''' for the homework. The first is recommended for novices. The second is for those who are either comfortable with Perl, or feel the need for a challenge this early. Only complete ONE of these assignments, as I will only accept one. Please follow the guidelines listed [[#Programming Assignment Expectations|above]].
+#Examine Table I, select representative species from Bergey’s Manual.  Select 2 prokaryotic species from each group, giving 14 prokaryotic species total.  Also select the Eukaryotic representative, Saccharomyces cerevisiae.
+#Access the NCBI website: http://www.ncbi.nlm.nih.gov/
-# Copy the code from page 221 in a new file. (Remember to put the code from the slides in the beginning of the file and to declare all variables on first use!) You must alter the code so that the resulting program accomplishes the following four tasks:
+#Under the “Search” category, select “Nucleotide”
-##Instead of taking the average of 10 numbers, ask the user how many numbers to average and use that number instead. (Hint: see how the code asks for each number). This must be stored in a new variable.
+#Under the “for” category, type the accession number for your first organism, and hit the “Go” button.  This takes you to the access for the 16S rRNA for your organism.
-##If the number the user gave was 0 or negative, print a message telling the user so, and exit immediately. You can exit using <pre>exit;</pre>
+#Download the 16S rRNA sequence for your first organisms by choosing “FASTA” under the “Display” category.
-##The code always prints 'Enter another number:'. Change it so that on the '''first time only''' it instead prints 'Enter a number:'.
+#Copy and paste the entire output into a Microsoft Word file.
-##Just before printing the average, print a message saying 'The numbers to average are: '. Then print out out all the numbers the user entered.
+#Edit the sequence id to match the format of “Genus_Species_Genbank#” (eg. > Escherichia_coli_174375).
-#More advanced programmers can try this assignment (you may wish to read all of Appendix 1 now): create a script which can take as input one or more DNA sequences from a file and translate directly to the correct amino acid sequence (single-letter format). You may implement this program in Perl however you wish, with as much complexity as you wish, as long as it meets the guidelines above and satisfies the following four criteria:
+#Repeat process for all of your organisms, pasting the sequences into the same Microsoft Word file. (note: be sure to place a blank line between each sequence entry)
-##The format of the input file it reads must be: one DNA sequence per line, so that each DNA sequence is separated by a new line character. '''Also assume you are given the coding strand.'''
+#Access the EMBL CLUSTALW alignment website: http://www.ebi.ac.uk/Tools/clustalw/, and copy and paste your entire Microsoft Word file into the area which asks you to “Enter or paste a set of sequences in any supported format”. Click “Run”.  This program will make an alignment of all of your sequences.
-##The name of the input file cannot be hard coded. You may either ask the user for the file location/name or take it as a command line argument.
+#Click “Show as Phylogram Tree” to create a tree showing the relatedness of your organisms based on their 16S rRNA sequences.
-##It must tolerate all upper-case, lower-case or mixed-case sequences in the input
+#To print your phylogram tree:
-##For every input DNA sequence, output the DNA sequence, the equivalent RNA, and the peptide sequence. The output '''must''' be informative, ie:
+##:hit the “Print Screen” button on your keyboard
-##:Input: atgcgtcgataa
+##:open the Paint program from your “accessories” menu on your computer
-##:Output: augcgucgauaa
+##:hit paste to paste your screen
-##:Peptide: MRR*
+##:“select” your phylogram tree
-#:Additionally, the program cannot use any outside dependencies/modules such as BioPerl (supposing you know how to use it.) Also note that STOP codons are denoted by a '<nowiki>*</nowiki>'
+##:copy and paste it into a new paint file
+##:print your tree and email it to yourself
 |-style="background-color:powderblue;"
 | '''Problems'''<br />