Category Archives: sordariomycetes

Postdoc: Uppsala University on Meiotic Drive in Fungi

POST-DOCTORAL POSITION IN THE EVOLUTION OF MEIOTIC DRIVE

A two-year postdoctoral position is available in the research group of professor Hanna Johannesson, at the Evolutionary Biology Centre (EBC), Uppsala University.

Conflicts arising from selfish genetic elements are important drivers for evolutionary change and innovation, and thus of crucial importance for genetic form and function.  The main goal of this project is to study the evolutionary dynamics of meiotic drive in fungi.  The study system is the Spore killers of Podospora anserina, a filamentous ascomycete. The ultimate aim of our research group is to combine large-scale genomic analyses with theoretical and experimental investigations to study the evolutionary dynamics of this meiotic drive system, both on a short and a long evolutionary timescale. This postdoc project will be developed after the interest of the applicant, but should preferably encompass a combination of experimental and genomic aspects. It will be a part of a collaborative effort within our research group.

Applicants should have a PhD in biology/evolutionary biology. Documented skills in molecular phylogenetics and/or population genetics, experimental and genomic work, especially using fungal model systems, is highly valued.

Start date is flexible, ideally February 1, 2016. The position may be
extended for up to two more years.

Please send your application materials by November 25 to
Hanna.Johannesson@ebc.uu.se. The application shall include: 1) a cover letter stating research interests, 2) a CV, including publication
record, 3) a short (1-2 page) description of research accomplishments, and 4) name and contact information for three references.

Please feel free to contact me at the above listed e-mail with
questions.

Nuclear Pore Complex studied in thermophilic fungus

ResearchBlogging.orgSometimes choosing a hot lover can make all the difference. In this case, choosing a thermophilic fungus was the right eukaryote for the job to purify stable proteins from the nuclear pore complex and test their interactions. Since high temperatures (60C as compared to what its relative Chaetomium globosum prefers, 24C) will denature proteins, this fungus has evolved the ability to still fold up proteins nicely at those high temperatures. Thus at more standard laboratory room temperature or below, these proteins should be really stable and easier to work with.  This manuscript (not OpenAccess sadly) includes the genome sequence of Chaetomium thermophilum sequenced with 454 FLX and XLR at 24X and assembled into 20 scaffolds – (8 chromosomes expected so they say – and I agree – this is quite good).The used the Celera assembler to make this final assembly for those of you taking notes at home on how to assemble your fungal genomes. The genome is available for download at the authors’s site or at GenBank. Their assembly is quite a bit smaller (28.3 Mb) than the related C. globosum (34.9) or Neurospora crassa genome (41Mb – though the authors use the old version and report 39.2; they also say “*based on the published genome (Galagan et al., 2003), although there is a newer assembly of N. crassa available from Broad, the newer assembly is not annotated for protein coding genes yet.” which is kind of weird because there is an annotated version here). I do wonder if the tendency of repeated elements to be collapsed in the assembly process resulted in a smaller assembly or if this really does have a smaller genome and less genes (~7k genes while Neurospora has ~10k).  Also worth noting that several other thermophilic fungi have been public for a while at the JGI too – Thielavia terrestris and Sporotrichum thermophile and our lab and others are investigating the genome content and how some genome properties like transposons have evolved in these lineages.

The thermophilic adaptation of this fungus has lead to stable proteins which can be studied more easily than mesophilic fungi. They have been able to determine how the nucleoporins (Nups) interact because of the biochemical and structural assays that are possible with the more stable protein complexes. This highlights the value of targeting an experimental system that has the properties needed and the simple and straightforward tactics needed to generate and use the genome sequence (the genome is but a minor note in the findings of this paper).  I can only wonder why none of my de novo genome assemblies go together as nicely as this one, but I’m excited to see this work present new insights into the biology of nuclear pore complexes.

Amlacher, S., Sarges, P., Flemming, D., van Noort, V., Kunze, R., Devos, D., Arumugam, M., Bork, P., & Hurt, E. (2011). Insight into Structure and Assembly of the Nuclear Pore Complex by Utilizing the Genome of a Eukaryotic Thermophile Cell, 146 (2), 277-289 DOI: 10.1016/j.cell.2011.06.039

Ncrassa v5 annotation released

The Missing PieceAs an update to previous post, the N. crassa annotation has been updated to version 5 on the Broad Institute website. Previously the data was not yet available for this update, but as of 8-Mar-2011 it is.  The assembly hasn’t changed but the annotation is updated and includes some fixes to improperly renamed locus names.  On the N. crassa genome site you can see files with the history of loci through this to determine if a locus name was improperly changed in the past. This should be rectified in the currently released annotation, and definitely encourage you to take it for a spin and report back to the Broad Institute if you have any questions.

Neurospora annotation update (v5)

Here is a message from the Broad Institute about a gene annotation update that was made recently in response to an issue that was revealed in the June 2010 release.  This new version is called V5 and should be on its way to GenBank.

Dear Neurospora scientists,

Recently we discovered an issue with the way locus tags were assigned
to our most recent Neurospora gene set, released publicly on the Broad
website in June of 2010. Many genes in this gene set have mismatched
locus numbers compared to the same genes released in February 2010.
Adding to the confusion, both releases were labeled version 4.

To remedy this we have recalled the June locus numbers and released a
new, version 5 gene set. Genes in this set have been numbered to
preserve historical locus numbers (back to the original genbank
release) as much as possible.

Folks who call their favorite genes by their v1, v2 or v3 numbers can
search for them on our web page, which will map them to v5
automatically and accurately. The same will work for most v4 numbers.
Unfortunately, 863 genes have different locus tags in the two v4
releases. If you search for one of them, you will get two hits - the
v5 gene that the February edition mapped to, and the v5 gene that the
June edition mapped to.

Two examples to clarify:

A. Suppose you search for NCU11713.4 on our web page. This query will
retrieve two genes, NCU11688.5 and NCU11713.5. The gene which in the
February release was called NCU11713.4 is the same as NCU11688.5,
while the gene labeled NCU11713.4 in June is the same as NCU11713.5.

B. Searching for NCU11324.4 yields but one hit because that gene, like
most genes, was consistently numbered between the two releases labeled
4.

If you are not sure when you downloaded your genes, the following may
help. If you see any of these locus numbers in your gene set:

NCU00129.4, NCU00457.4, NCU00499.4, NCU00556.4, NCU00627.4,
NCU00685.4, NCU00768.4, NCU00856.4, NCU00986.4, NCU01064.4,
NCU01065.4, NCU01282.4, NCU01299.4, NCU01300.4, NCU01483.4,
NCU01559.4, NCU01560.4, NCU01610.4, NCU01611.4, NCU01664.4,
NCU01665.4, NCU01871.4, NCU01903.4, NCU02200.4, NCU02259.4,
NCU02666.4, NCU02758.4, NCU02837.4, NCU02998.4, NCU03047.4,
NCU03206.4, NCU03773.4, NCU04239.4, NCU04240.4, NCU04518.4,
NCU04519.4, NCU04710.4, NCU04711.4, NCU05275.4, NCU05512.4,
NCU05776.4, NCU06013.4, NCU06370.4, NCU06732.4, NCU07107.4,
NCU07259.4, NCU07260.4, NCU07301.4, NCU07405.4, NCU07856.4,
NCU07857.4, NCU08090.4, NCU08182.4, NCU08323.4, NCU08332.4,
NCU09085.4, NCU09256.4, NCU09257.4, NCU09998.4, NCU10166.4,
NCU10574.4, NCU11040.4, NCU11240.4, NCU11253.4, NCU11376.4,
NCU11390.4, NCU11393.4

then your genes are from the February 2010 gene set. However, if you see

NCU00082.4, NCU00083.4, NCU00084.4, NCU00085.4, NCU00516.4,
NCU01819.4, NCU04299.4, NCU04300.4, NCU04301.4, NCU04302.4,
NCU04303.4, NCU04304.4, NCU04305.4, NCU05000.4, NCU05111.4,
NCU05112.4, NCU05113.4, NCU05114.4, NCU05115.4, NCU05116.4,
NCU05448.4, NCU05452.4, NCU06667.4, NCU07323.4, NCU09066.4,
NCU10179.4, NCU10301.4, NCU10379.4, NCU10383.4, NCU10753.4,
NCU10866.4, NCU10914.4, NCU11068.4, NCU11182.4, NCU12157.4,
NCU12158.4, NCU12159.4, NCU12160.4, NCU12161.4, NCU12162.4,
NCU12163.4, NCU12164.4, NCU12165.4, NCU12166.4, NCU12167.4,
NCU12168.4, NCU12169.4, NCU12170.4, NCU12171.4, NCU12172.4,
NCU12173.4, NCU12174.4, NCU12175.4, NCU12176.4, NCU12177.4,
NCU12178.4, NCU12179.4, NCU12180.4, NCU12181.4, NCU12182.4,
NCU12183.4, NCU12184.4, NCU12185.4, NCU12186.4, NCU12187.4, NCU12188.4

then your genes are from the June 2010 release.

Attached please find five mapping tables which can be used to migrate
locus numbers from any of the previous releases to the latest version
5 locus tags (linked below).

We apologize for any confusion this may cause.
Love,
The Broad Institute

I’ve also uploaded the locus update files which maps between versions of the annotation.

FGSC – a key partner in fungal biology research

FGSC logoAn article about the Fungal Genetics Stock Center written by the curators provides some insight into the 50 year history of this resource. It is a great summary of how the stock center has grown over the years and demonstrates how it is an essential aspect of how research on filamentous fungi is possible. The FGSC staff also provide important infrastructure in organization of meetings like the Neurospora and Fungal Genetics meetings and are also active pursuing their own research.  So don’t forget to cite FGSC in  your talks and (very importantly) papers.

McCluskey K, Wiest A, & Plamann M (2010). The Fungal Genetics Stock Center: a repository for 50 years of fungal genetics research. Journal of Biosciences, 35 (1), 119-26 PMID: 20413916

Hey there fluffy

ResearchBlogging.orgI spy a picture of Neurospora growing on the cover of Genetics this month.  The cover highlights the results from the work of the lab of Luis Corrochano who works on  light regulation in a variety of systems like Neurospora and Phycomyces.  This work describes their work on the fluffy gene which regulates conidiation (production of conidia or asexual spores). They show that an important interplay between an inducer of light response, the White Collar Complex (WCC), and the FLD protein on fluffy.  The data from indicate hat FLD represses fluffy as a response to dark but that this repression is removed in response to light through the action of WCC.

Olmedo, M., Ruger-Herreros, C., & Corrochano, L. (2009). Regulation by Blue Light of the fluffy Gene Encoding a Major Regulator of Conidiation in Neurospora crassa Genetics, 184 (3), 651-658 DOI: 10.1534/genetics.109.109975

For your reading pleasure

Too much on my plate as of late, so I’m woefully behind on posting much on interesting papers or news.  Here’s a short list of links and papers that are worth a look though.

  • “Evolution of pathogenicity and sexual reproduction in eight Candida genomes” published (Nature)
  • NYT Science article sort of summarizing the good, bad, and ugly of fungi and human interactions
  • Attempts to save amphibians from chytridiomycosis “Riders of a Modern-Day Ark” (PLoS Biology)
  • Looks like Scott Baker with the JGI are in the process of resequencing several classical mutant strains of Phycomyces, Neurospora and Cochliobolus, Cryphonectria for sequence-based mapping of mutants (i.e. here and here and here).

First release of N.tetrasperma and N.discreta

The JGI in collaboration with our lab at Berkeley have released the Neurospora tetrasperma (mat A) and N. discreta (mat A) genome sequences and annotation after about two years of work.  These are two closely related species to the well studied laboratory workhorse Neurospora crassa.

The N.tetrasperma assembly (8X) has an N50 of 976kb and is highly colinear with the N.crassa genome.  With the JGI, we’ve also done some additional 454 sequencing which will represent an improved assembly and 23X coverage in the next release.  We also did some comparative scaffolding and can basically double that N50 – most of which looks good when compared to the improved V2 assembly.

The N.discreta assembly (8X) is also quite good with an N50 of 2.3 Mb. For comparison, the V7 of N.crassa has an N50 of 664 kb. although with genetic map information the 250+ contigs can be scaffolded into 7 chromosomes with 146 unmapped contigs.

Both N.discreta and N.tetrasperma genomes contain about 10k predicted genes similar to counts in other related species like N.crassa and Podospora anserina.

We’re finalizing several analyses to present at the Asilomar meeting to describe these Neurospora genomes and comparisons with other Sordariomycete species.

Fungal genome assembly from short-read sequences

This is a research blog so I though I’d post some quick numbers we are seeing for de novo assembly of the Neurospora crassa genome using Velvet. The genome of N.crassa is about 40Mb and sequencing of several flow cells using Solexa/Illumina technology to see what kind of de novo reconstruction we’d get. I knew that this is probably insufficient for a very good assembly given what has been reported in the literature, but sometimes it is helpful to give it a try on local data.  Mostly this is a project about SNP discovery from the outset. I used a hash size of 21 in velvet with an early (2FC) and later (4FC) dataset. Velvet was run with a hashsize of 21 for these data based on some calculations and running it with different hash sizes to see the optimal N50.  Summary contig size numbers come from the commands using cndtools from Colin Dewey.

  faLen < contigs.fa | stats

2 flowcells (~10M reads @36bp/read or about 10X coverage of 40Mb genome)

            N = 199562
          SUM = 25463251
          MIN = 49
 1ST-QUARTILE = 87
       MEDIAN = 107.0
 3RD-QUARTILE = 146
          MAX = 5371
         MEAN = 127.59568956
          N50 = 130

4 flow cells  (~20M reads @36bp/read; or about 20X coverage of a 40Mb genome)

            N = 102437
          SUM = 38352075
          MIN = 41
 1ST-QUARTILE = 77.0
       MEDIAN = 153
 3RD-QUARTILE = 467
          MAX = 7189
         MEAN = 374.396702363
          N50 = 837

So that’s N50 of 837bp – for those used to seeing N50 on the order or 1.5Mb this is not great.  But from4 FC worth of sequencing which was pretty cheap.  This is a reasonably repeat-limited genome so we should get pretty good recovery if the seq coverage is high enough. Using Maq we can both scaffold the reads and recover a sufficient number of high quality SNPs for the mapping part of the project.

To get a better assembly one would need much deeper coverage as Daniel and Ewan explain in their Velvet paper and shown in Figure 4 (sorry, not open-access for 6 mo). Full credit: This sequence was from unpaired sequence reads from Illumina/Solexa Genomic sequencing done at UCB/QB3 facility on libraries prepared by Charles Hall in the Glass lab.