[maker-devel] diff. numbers of geneson contigs vs. scaffolded genome

[Stefan Zoller]

Hi Carson
Thanks again for your help and suggestions. They are very helpful indeed!

I have now:
1) created a species specific repeat library, or actually several 
versions (e.g., filtered for hits on known plant transposable elements 
etc., or filtering out hits on proper plant proteins), and ran Maker 
with it on a subset of the genome. Whatever version of repeat library I 
use, I get +/- 5% the same number of Maker approved proteins. I get 
slightly more proteins with the "best" species specific repeat library, 
so I think it does make a difference, however not a big one. 
Interestingly, if I turn off the repeat masking totally, I get about 20% 
more Maker approved protein models. So either I am doing something 
totally wrong here or the repeat masking is working quite well with the 
specific repeat libraries.

2) filtered the non-overlapping ab-initio proteins with PFAM domains 
according to your how-to. This works very nicely, thanks. However, I get 
quite a lot of models with PFAM hits, even when stringently filtering 
for e-value. For example, in the subset of the contiged genome I usually 
get around 300 Maker models. And now I have an additional 180 from the 
"non-overlapping-with-PFAM-domain" when filtering for e-value <1e-20. 
For e-value < 1e-10 it would be 280, almost twice the number of 
proteins. Extrapolating this to the full genome, this would be more than 
32'000 proteins. This seems a bit excessive and I am not sure if I am 
even supposed to use such a stringent e-value filtering. One reason of 
having so many additional proteins I can think of, is that augustus and 
snap are predicting similar non-overlapping models for the same location 
and of course they then both have a PFAM domain. I can actually see this 
for some locations when I load the data in WebApollo. I can think of a 
crude way to select only the "best" model for a location (while 
preferably also considering the already Maker approved protein) but I 
wonder if maybe there is already a solution for this in Maker?

In short, I think the repeat masking seems not to be the problem (And I 
think I have put quite some effort in the repeat library creation). On 
the other hand, there are a lot of "good" models in the non-overlapping 
proteins that could be filtered and promoted to proper models, if I only 
could make the right selection.

Maybe, based on these additional informations you could point out 
additional tests, filtering approaches or analyses I could do to home-in 
to the "good" gene models in the non-overlapping gene models (or Maker 
approved gene models in general).

Thanks again for your help!
Stefan



On 25.09.14 20:17, Carson Holt wrote:
> Sorry for the slow reply.  I was trying to locate a script that might be
> useful for you.
>
> I think a species specific repeat libary will be of most benefit here
> (it's surprising just how influential this step is).  Also note that you
> should train SNAP and Augustus on your species and are not just using
> another related species as a stand in.
>
> With respect to PFAM domains, on some organisms you may not get a lot of
> cross species protein alignments because of divergence or assembly issues.
> This of course makes it harder to support these models with direct protein
> alignments.  However you can run InterProscan over the
> non-overlapping.proteins.fasta file produced by MAKER (contains
> non-redundant rejected models).  Because an HMM is used for domain
> identification, it can pick up protein domains that would not produce a
> significant BLAST alignment because of divergence. You can then add models
> with positive hits for protein domains back into your gene set.
>
> This ad hoc procedure usually can only increase gene counts by about 10%
> though for organisms where it's required. I've attached a script that
> makes generating results for these genes easier.
>
> 1. First you run InterProScan with just PFAM.
> 2. Then you take the IDs of all models that have a domain in the report
> and create a list (1 ID per line).
> 3. Next use the fasta_tool script that comes with MAKER together with the
> --select flag to separate just the positive hits (ID's in your list) from
> the non-overlapping.proteins.fasta and non-overlapping.transscripts.fasta
> files.
> 4. Use the attached script to separate just the positive hits (your ID
> list) from the GFF3. The script will upgrade match/match_part results to
> gene/mRNA/exon/CDS results and print them out for you.
> 5. Use the fasta_maerge and gff3_merge scripts that come with MAKER to
> merge the selected/upgraded GFF3 entries and selected FASTA entries back
> into the original MAKER results.
>
> --Carson
>
>
>
> On 9/23/14, 6:36 AM, "Stefan Zoller" <stefan.zoller at env.ethz.ch> wrote:
>
>> Please forgive my ignorance, I am not entirely sure if I understand your
>> question correctly, but I will try to answer.
>> As evidence we use:
>> 1) our own transcriptome (trinity assembled RNAseq, filtering out the
>> very low expression transcripts).
>> 2) all swissprot plant proteins, and several protein sets from closely
>> related plant species downloaded from NCBI.
>> I am not sure if the ab-initio predictions without evidence have pfamm
>> domains. Honestly, I would not know how to tell and how to
>> include/exclude.
>> I was assuming that we should not have too many Maker approved
>> predictions without evidence anyway, because we use "keeps_preds=0".
>> The numbers of gene predictions I mentioned in my email are the
>> predictions reported by the fasta_merge/gff3_merge scripts in the
>> "*maker.proteins.fasta". There are of course many more predictions in
>> e.g., "*maker.augustus_masked.proteins.fasta" (about 68'000 in this file).
>>
>> I hope I am not totally off with my answer.
>> Cheers, Stefan
>>
>>
>>
>> On 23.09.14 02:10, Mark Yandell wrote:
>>> Also are you numbers including the ab-inito predictions without
>>> evidence that have pfamm domains?
>>>
>>> cheers,
>>>
>>>
>>> --mark
>>>
>>>
>>>
>>> Mark Yandell
>>> Professor of Human Genetics
>>> H.A. & Edna Benning Presidential Endowed Chair
>>> Co-director USTAR Center for Genetic Discovery
>>> Eccles Institute of Human Genetics
>>> University of Utah
>>> 15 North 2030 East, Room 2100
>>> Salt Lake City, UT 84112-5330
>>> ph:801-587-7707
>>>
>>> ________________________________________
>>> From: maker-devel [maker-devel-bounces at yandell-lab.org] on behalf of
>>> Carson Holt [carson.holt at genetics.utah.edu]
>>> Sent: Monday, September 22, 2014 2:17 PM
>>> To: stefan.zoller at env.ethz.ch; maker-devel at yandell-lab.org
>>> Subject: Re: [maker-devel] diff. numbers of geneson contigs vs.
>>> scaffolded      genome
>>>
>>> The contiged assembly is more likely to give spurious hits and
>>> alignments.
>>>    They also can be harder to repeat mask.  Also gene predictors can
>>> behave
>>> slightly different on small sequences than on longer ones.  If you have
>>> fewer gene models than you expect, your first step should be to process
>>> the scaffolds with CEGMA.  It will give you an estimate of the genomes
>>> "completeness".  If CEGMA gives a 60% completeness value for example
>>> then
>>> you can expect to only recover 60% of the expected number of genes. Next
>>> you should run RepeatModeler of similar software to help generate a
>>> species specific repeat library.  Under masked repeats can make
>>> predicting
>>> genes on longer scaffolds far more difficult for ab initio predictors.
>>>
>>> --Carson
>>>
>>>
>>> On 9/19/14, 12:32 AM, "Stefan Zoller" <stefan.zoller at env.ethz.ch> wrote:
>>>
>>>> Hi,
>>>>
>>>> I am working on the annotation of a plant genome (about 600MB) and we
>>>> have a reasonable draft assembly, a fairly good transcriptome and quite
>>>> a few proteins from related species. We have also extensively trained
>>>> augustus and are also feeding genmark and snap predictions.
>>>>
>>>> Recently I noticed a behavior of Maker that seems fairly odd and which
>>>> I
>>>> cannot explain at all. When I take the scaffolded genome (about 23000
>>>> scaffolds) I get roughly 9'000 maker approved gene models. Which is
>>>> admittedly a bit on the low side and we have to work on this. However,
>>>> when I break up the scaffolds into contigs at stretches of N longer
>>>> 500bp (about 60'000 contigs) I get about 17'000 maker gene models. Now
>>>> obviously 17'000 is more in the range what I would expect, so I am
>>>> inclined to go with these. I have looked at both annotations and the
>>>> evidence in WebApollo and the evidence alignments are identical for
>>>> both
>>>> runs. The approved genes seem to be the same, except for the additional
>>>> ones in the "contiged" genome version. The additional gene models are
>>>> not necessarily at the ends of the contigs, so I think it has nothing
>>>> to
>>>> do with having the stretches of Ns nearby in the scaffolded genome. Do
>>>> you have any idea why maker comes up with the additional numbers of
>>>> gene
>>>> models and how I could "convince" maker to give me the same gene models
>>>> for the scaffolded assembly?
>>>>
>>>> Cheers,
>>>> Stefan
>>>>
>>>>
>>>>
>>>> --
>>>> Stefan Zoller, PhD
>>>> Bioinformatics
>>>> Genetic Diversity Centre
>>>> ETH Zurich CHN E55.1
>>>> Universitätsstrasse 16
>>>> 8092 Zurich
>>>> Switzerland
>>>>
>>>> Phone: +41 44 632 66 85
>>>> E-Mail:  stefan.zoller at env.ethz.ch
>>>> Web: www.gdc.ethz.ch
>>>>
>>>>
>>> _______________________________________________
>>> maker-devel mailing list
>>> maker-devel at box290.bluehost.com
>>> http://box290.bluehost.com/mailman/listinfo/maker-devel_yandell-lab.org

-- 
Stefan Zoller, PhD
Bioinformatics
Genetic Diversity Centre
ETH Zurich CHN E55.1
Universitätsstrasse 16
8092 Zurich
Switzerland

Phone: +41 44 632 66 85
E-Mail:  stefan.zoller at env.ethz.ch
Web: www.gdc.ethz.ch