JBrowse 2: Searching for features and sequences

Searching in JBrowse 2 is quite similar to searching in JBrowse 1. The most common way you would look for a feature would be to type the name of a feature in the location field (that is, the field that has the current location in it, like this:

Anything that you could search for in JBrowse 1 you can search for in JBrowse 2, and there is a good reason for that: they are using exactly the same data and search indexes. So, you can look for gene and transcript names, identifiers like WBGene00006749, and allele names like pkP649.  Of course, you can also enter a location like II:100000..200000. The only difference in name searching between JBrowse 1 and 2 is that when you search for something, you will almost always get a message like this in the bottom of the screen:

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JBrowse 2: Getting Sequence

In JBrowse 2 there are multiple ways to obtain sequence information. One is via a context menu when region is selected by clicking and dragging on the “number line” part of the linear genome view:

Selecting “Get sequence” from the context menu will open a dialog where you will have a few options for how to get your sequence:

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Getting DNA sequence from JBrowse

There are two ways that users can download DNA sequence from JBrowse: in relation to a feature, like a gene, or by specific sequence coordinates.

Getting Sequence for a Gene or Transcript

To get the sequence for a gene, open any of the “Curated Genes” tracks and right click or control click on the feature and select “View Sequence” from the resulting popup menu. If you are using the main “Curated Genes” track, you’ll get a dialog box asking which transcript you want to view. It does this because it needs to know what subfeatures like exons and introns can be shown. If you’re using one of the “type-specific” tracks (like “Curated Genes (noncoding)”), you won’t see this dialog because these tracks show individual transcripts rather than grouping the transcripts together like the “main” gene track does. It’s possible (in fact, likely) that you’ll be displayed a warning message about overlapping subfeatures (since exons and CDS overlap) and then be presented with a dialog box containing a list of subfeatures with buttons and the sequence below them. The buttons allow modifying the sequence display to highlight, hide or change the case of the subfeatures selected. For example, you could do an “in silico mRNA processing” by hiding the introns. In addition, there are drop down menus for showing a set range of up or downstream sequence, up to 4kb. This sequence can then be selected, copied and pasted into word processing program with highlighting preserved. Of course, hiding or changing the case will be preserved regardless of where it is pasted into.

Screen Shot 2019-02-12 at 8.53.04 AM

Two Important Notes

  1. The highlighting tool doesn’t always get the subfeatures right! It sometimes gets confused when calculating boundaries and their overlaps. If it’s important, please take the time to check the results before using them.
  2. Highlighting doesn’t always get preserved when cutting and pasting, and it seems to depend on what browser is being used. In my hands, it works in Firefox but not in Safari or Chrome.

Getting Sequence for Other (non-gene) Features

If there are features other than those that are gene related, the process is similar. Control or right click on a feature and select “View Details” from the popup menu. The resulting dialog contains all of the information that JBrowse “knows” about the feature and, as long as it isn’t too long (ie, less than 250kb), will contain the sequence of the feature. In this instance you don’t even need to select and copy to get the sequence, since there is a “save as FASTA” button.

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Getting Sequence of a Specific Range

If you need some other range of sequence not directly associated with a feature, we will make use of the “Save track data” functionality that is built into every track. In this instance, we want to use the reference sequence track to get its data (ie, the DNA sequence). To do this, turn on the “Reference Sequence (DNA)” track. Then zoom, pan, search for a landmark or enter exact coordinates in the search field to the exact region that you want the sequence for. The coordinates are in the format “Chromosome:start..end” (like GBrowse, “II:20000..30000” for example). When you’re there, mouse over the track label (ie, the words “Reference Sequence (DNA)” in the JBrowse view) and the track label will become more opaque and a down triangle will appear, indicating a menu is available.

Click on that triangle and select “Save track data” from the menu. You will be presented with a dialog menu that will let you either view or save the visible region as FASTA. There isn’t an option to pick where it gets saved, so look for it in your default download location, typically a Downloads folder. A useful side note is that this option is available for every track, so you can always download the data for the track you are looking at regardless of the data type.

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Creating Hi-Res Screenshots in JBrowse

higher-res screenshot of JBrowse

While the new genome browser (JBrowse) implemented at WormBase has several advantages, like faster browsing and a faceted track selector, it does lack a few features from the venerable GBrowse instance that has been at WormBase for many years.  While we and the JBrowse developers are working on addressing those minor shortcomings, this article is about how to circumvent one of those issues now.  

JBrowse lacks the ability to make a high resolution image like GBrowse.  While taking a screenshot can sometimes result in an acceptable image (for example, Macs with a retina display work pretty well), the result is not always suitable for publication or putting on a poster.  The method described here still does not allow for making an SVG image, but it does allow for higher quality PNG images than just taking a screenshot and also allows for the creation of a PDF document with the image in it.  Unfortunately, this method requires downloading a tool where we must edit one of the source files and then execute it on the command line.  While this is a little bit of a hassle, once it is set up, creating screenshots is quite easy.

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Introducing a new genome browser for WormBase

We are pleased to introduce a new genome browser that we are currently testing as a replacement for the current, long serving genome browser (GBrowse). The new browser, an implementation of JBrowse from the GMOD project, is currently available at wormbase.org/tools/genome/jbrowse/.  The new genome browser has a fast and pliable user interface; becoming oriented to the new browser should be relatively painless as it shares many design features in common with the current browser.

The new genome browser also has new functionality not available in the old one.  Key among these are (all of which are available from the genome browser’s file menu):

  1. Opening many types of data files (GFF, BAM, BigWig/BigBed, VCF), without having to upload them (so it’s *fast*).
  2. Creating combination tracks, where the contents of any two tracks can be combined using set or arithmetic operations.
  3. Making a sequence (DNA or amino acid) search track that will highlight when a motif is present (the search string can take the form of regular expressions–please let us know if you’d like help writing a regular expression).

Other useful features include the ability to “pin” a track to the top of the browser so it won’t scroll off the top of the page (simplifying visual comparisons with other open tracks), and a “full page” button that will open a new browser window where the genome browser takes up the full page.

Please try out the new browser and give us any feedback you can think of, either things you’d like to see, things you don’t like, whatever.