More recently, we've been enthused about using k-mer based similarity measures and computing and searching k-mer-based sketch search databases for all the things.

But I haven't spent too much talking about using k-mers for taxonomy, although that has become an ahem area of interest recently, if you read into our papers a bit.

In this blog post I'm going to fix this by doing a little bit of a literature review and waxing enthusiastic about other people's work. Then in a future blog post I'll talk about how we're building off of this work in fun! and interesting? ways!

Address of the bookmark: http://ivory.idyll.org/blog/2017-something-about-kmers.html

General information.

Field terminator is "\t|\t"

Row terminator is "\t|\n"

nodes.dmp file consists of taxonomy nodes. The description for each node includes the following

fields:

tax_id -- node id in GenBank taxonomy database

  parent tax_id -- parent node id in GenBank taxonomy database

  rank -- rank of this node (superkingdom, kingdom, ...) 

  embl code -- locus-name prefix; not unique

  division id -- see division.dmp file

  inherited div flag  (1 or 0) -- 1 if node inherits division from parent

  genetic code id -- see gencode.dmp file

  inherited GC  flag  (1 or 0) -- 1 if node inherits genetic code from parent

  mitochondrial genetic code id -- see gencode.dmp file

  inherited MGC flag  (1 or 0) -- 1 if node inherits mitochondrial gencode from parent

  GenBank hidden flag (1 or 0)            -- 1 if name is suppressed in GenBank entry lineage

  hidden subtree root flag (1 or 0)       -- 1 if this subtree has no sequence data yet

  comments -- free-text comments and citations

Taxonomy names file (names.dmp):

tax_id -- the id of node associated with this name

name_txt -- name itself

unique name -- the unique variant of this name if name not unique

name class -- (synonym, common name, ...)

Divisions file (division.dmp):

division id -- taxonomy database division id

division cde -- GenBank division code (three characters)

division name -- e.g. BCT, PLN, VRT, MAM, PRI...

comments

Genetic codes file (gencode.dmp):

genetic code id -- GenBank genetic code id

abbreviation -- genetic code name abbreviation

name -- genetic code name

cde -- translation table for this genetic code

starts -- start codons for this genetic code

Deleted nodes file (delnodes.dmp):

tax_id -- deleted node id

Merged nodes file (merged.dmp):

old_tax_id                              -- id of nodes which has been merged

new_tax_id                              -- id of nodes which is result of merging

Citations file (citations.dmp):

cit_id -- the unique id of citation

cit_key -- citation key

pubmed_id -- unique id in PubMed database (0 if not in PubMed)

medline_id -- unique id in MedLine database (0 if not in MedLine)

url -- URL associated with citation

text -- any text (usually article name and authors).

-- The following characters are escaped in this text by a backslash:

-- newline (appear as "\n"),

-- tab character ("\t"),

-- double quotes ('\"'),

-- backslash character ("\\").

taxid_list -- list of node ids separated by a single space

The vital metaphase stage of cell division, when the sister chromatids migrated to the centre and lined up in a row, and pulled apart using attached microtubules in such a way that half the DNA ends up in each daughter cell. However, before the mitotic spindle‐mediated movement gets start and pulled DNA apart, the chromosomes are free to undergo recombination which involves the exchange of genetic material either between multiple chromosomes or between different regions of the same chromosome.

During recombination, the precise breakage of each strand, exchange between the strands, and sealing of the resulting recombined molecules happens. The “chromosomal breakpoints” refers to these places where they break. Mostly, this process occurs with a high degree of accuracy at high frequency in both eukaryotic and prokaryotic cells. But occasionally this “break and sealing/ break and reattach” process goes wrong and the reattachment happens in the wrong place which usually create disaster (with few exceptions).These chromosome disaster or abnormalities involve the gain, loss or rearrangement of visible amounts of genetic material during cell division. These abnormalities are of two type, the first one is numerical abnormalities  where severe disorders are caused by the loss or gain of whole chromosomes, which affect the copy number of hundreds or even thousands of genes. The second are structural abnormalities which can be unbalanced or balanced. The former are similar to numerical abnormalities in that genetic material is either gained or lost. The natural defects in chromosome segregation are linked to cancer and several genetic diseases (http://en.wikipedia.org/wiki/List_of_genetic_disorders). Therefore, the enzymes involved in regulating cell division are still the attractive drug targets for many diseases.

Apart from certain chromosome abnormalities, these “crossing over” of segments of maternal and paternal chromosomes to form hybrid chromosomes have some evolutionary importance and considered as a driver of genetic variation. Moreover, the chromosome breakage in evolution is considered to be non-random in nature(http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.0020014). In addition the study of breakpoint regions and non-breakpoint (stable) regions of chromosomes indicates both the regions evolved in distinctly different ways ( http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2675965/). These breakage may lead to genetic diseases or participate to chromosomal rearranmgnets and contributed in development of new species.

I will try to explain the genome hotspots/Evolutionary Breakpoint Regions(EBRs)/fragile regions/weak fragments/  in my next blog.

Software for recombination detection:

RAT http://cbr.jic.ac.uk/dicks/software/RAT/

Breakpointer https://github.com/ruping/Breakpointer

DRP http://web.cbio.uct.ac.za/~darren/rdp.html

RB-finder http://www.ncbi.nlm.nih.gov/pubmed/18707535

LDhat2.0 http://ldhat.sourceforge.net/LDhat2.0/instructions.shtml

Reference:

http://www.nature.com/scitable/topicpage/genetic-recombination-514#

Image: Wikipedia , sciencelearn.org.nz

Recommended Articles:

http://www.friendshipcircle.org/blog/2012/05/22/13-chromosomal-disorders-youve-never-heard-of/

http://web.udl.es/usuaris/e4650869/docencia/segoncicle/genclin98/recursos_classe_%28pdf%29/revisionsPDF/chromosyndromes.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2775595/table/T2/

http://learn.genetics.utah.edu/content/disorders/chromosomal/

http://www.ncert.nic.in/html/learning_basket/biology/cc&cd.pdf

More at https://www.uibk.ac.at/limno/personnel/stelzer/index.html.en#research

http://www.nibmg.ac.in/academic/SyMeC-ICGC/SyMeC%20&%20ICGC_May%202018.pdf

http://www.nibmg.ac.in/academic/plp/15_05_2018/AdvertisementMay2018.pdf

Qualifications
Students currently in their pre-final or final year of BSc/BE/BTech or first year MSc/ME/MTech or equivalent with a good academic record are encouraged to apply through IMSc's formal application process.

To apply through the summer program jointly organized by the Academies of Science, please check the Indian Academy of Sciences for their application process: http://web-japps.ias.ac.in:8080/fellowship2018/index.html.
Stipend
Selected students will be paid 2nd class round trip train fare plus Rs.200 per diem. Accommodation will be provided in the hostel during summer, subject to availability. Since our ability to provide accomodation is often limited, we suggest that students also explore alternative possibilities for stay in Chennai. Accommodation will not be provided for longer visits.

Application Process
To apply for our summer programs please follow the instructions for the respective fields:
Theoretical Physics
Mathematics
Theoretical Computer Science
Computational Biology

Other information
If you have more questions about our application procedures, about your eligibility or simply about life and work at IMSc, do write to any of the faculty members listed on our home page.

PhD Opportunities in Denmark Denmark boasts a robust academic infrastructure with world-class universities. Here are some essential resources:

Study in Denmark: https://studyindenmark.dk

Aarhus University: https://phd.au.dk

Euraxess Denmark: https://euraxess.dk

Technical University of Denmark (DTU): https://dtu.dk

University of Copenhagen: https://phd.ku.dk

Copenhagen Business School: https://cbs.dk

Jobindex: https://jobindex.dk

Roskilde University: https://ruc.dk

University of Southern Denmark: https://sdu.dk

Academic Positions Denmark: https://academicpositions.dk

PhD Opportunities in Sweden Sweden is renowned for its innovation-driven academic culture. Here’s where you can find opportunities:

FindAPhD Sweden: https://findaphd.com/phds/sweden

Euraxess Sweden: https://euraxess.se

Academic Positions Sweden: https://academicpositions.se

KTH Royal Institute of Technology: https://kth.se

Lund University: https://lu.se

Uppsala University: https://uu.se

Chalmers University of Technology: https://chalmers.se

Linköping University: https://liu.se

Stockholm University: https://su.se

Swedish University of Agricultural Sciences (SLU): https://slu.se

Study in Sweden: https://studyinsweden.se

Malmö University: https://mau.se

PhD Opportunities in Norway Norway offers unique research opportunities, complemented by its stunning natural landscapes:

JobbNorge: https://jobbnorge.no

Euraxess Norway: https://euraxess.no

University of Oslo: https://uio.no

Norwegian University of Science and Technology (NTNU): https://ntnu.edu

Norwegian Business School (BI): https://bi.edu

Norwegian School of Economics: https://nhh.no

Norwegian University of Life Sciences (NMBU): https://nmbu.no

Norwegian School of Sport Sciences: https://nih.no

University of Bergen: https://uib.no

Nord University: https://nord.no

UiT The Arctic University of Norway: https://uit.no

PhD Opportunities in Finland Finland’s education system emphasizes research excellence and innovation. Explore these resources:

FindAPhD Finland: https://findaphd.com/phds/finland

Euraxess Finland: https://euraxess.fi

University of Helsinki: https://helsinki.fi

Aalto University: https://aalto.fi

University of Turku: https://utu.fi

Tampere University: https://tuni.fi

University of Eastern Finland: https://uef.fi

University of Jyväskylä: https://jyu.fi

Åbo Akademi University: https://abo.fi

Hanken School of Economics: https://hanken.fi

LUT University: https://lut.fi

Conclusion The Nordic countries offer exceptional opportunities for PhD aspirants. From top-ranked universities to specialized research institutions, the possibilities are endless. Bookmark PhD Hut as your starting point, and let these resources guide you to your academic aspirations.

Campaign calendar:

- Opening date for applications: January 30, 2020
- Deadline for applications: March 5, 2020
- Pre-selections: April-May 2020
- Final selections: May-June 2020
- Starting date for appointments: from September 2020

More at https://jobs.inrae.fr/en/open-competitions/open-competions-research-scientists-crcn