• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Tandem Repeats and Satellite DNA in Bovideae - Colloquium on Animal Cytogenetics
 

Tandem Repeats and Satellite DNA in Bovideae - Colloquium on Animal Cytogenetics

on

  • 177 views

Tandemly repeated satellite DNA in the Artiodactyla - a lecture ...

Tandemly repeated satellite DNA in the Artiodactyla - a lecture
Tandemly repeated, satellite, DNA sequences are an abundant component of the genome of most species, including the Artiodactyla. Multiple DNA familes are present, each in long tandem arrays, with members of each family present on one or more chromosomes at characteristic positions. In particular, several familes are located at the centromeres of most chromosomes, including acrocentrics, metacentrics and the sex chromosomes. Individual arrays are made up of variants of particular sequence motifs, which may be longer than 1,500 bp. In this presentation, we will discuss aspects of the evolution of repetitive sequences within and between chromosomes, with comparative data between different species. With pig, we will show details of the localization of tandem repeats at meiosis, and how these sequences relate to sequence amplification and loss, as well as the epigenetic behaviour of the resulting heterochromatin. In the Bovinae, we will show how molecular cytogenetic methods are essential to build up a full picture of the behaviour and distribution of satellite DNA where current sequencing methods are unable to assemble the sequences blocks accurately.

P. Heslop-Harrison1, T. Schwarzacher1 and R. Chaves2 (Phh4@le.ac.uk)
University of Leicester, Biology, Leicester LE1 7RH UK; 2Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal

Statistics

Views

Total Views
177
Views on SlideShare
173
Embed Views
4

Actions

Likes
1
Downloads
3
Comments
1

2 Embeds 4

https://twitter.com 2
http://www.slideee.com 2

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

CC Attribution-NonCommercial-ShareAlike LicenseCC Attribution-NonCommercial-ShareAlike LicenseCC Attribution-NonCommercial-ShareAlike License

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel

11 of 1 previous next

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Tandem Repeats and Satellite DNA in Bovideae - Colloquium on Animal Cytogenetics Tandem Repeats and Satellite DNA in Bovideae - Colloquium on Animal Cytogenetics Presentation Transcript

    • Tandemly repeated satellite DNA in the Artiodactyla Pat Heslop-Harrison Trude Schwarzacher Raquel Chaves University of Leicester, UK Universidade de Trás-os-Montes e Alto Douro, Portugal www.molcyt.com Twitter/slideshare Pathh1 phh@le.ac.uk
    • Chromosomal changes are one of the most important features of evolution Bovideae: 58 autosomal arms Cow: 2n=60 (29 pairs of acrocentric autosomes + X, Y) Sheep: 2n=54 (25 acrocentric + 2 submetacentric pairs + X, Y)
    • Bos taurus taurus vs Bos taurus indicus: 2n=60, XY But: B. taurus submetacentric Y B. indicus acrocentric Y
    • Robertsonian Fusion of 1 and 29 to give 2n=58 or 59: Gustavson 1964 Heterozygous rob(1;29) example in Portuguese cattle Barrosa Chaves et al. Chromosome Research
    • Repetitive DNA sequences – LINE/SINE transposons and satellite DNA – are the most abundant genome component - Often ‘masked’ (ignored) during sequence assembly - Satellites ‘collapse’ from hundreds of tandem repeats to a few - Often functional regarding centromeric behaviour and methylation/ heterochromatinization
    • Robertsonian Fusion (+ )
    • Chaves et al. Chromosome Research
    • Complex satellite DNA reshuffing in the polymorphic t(1;29) Robertsonian translocation and evolutionarily derivedchromosomes in cattle Chaves, Adega, Heslop-Harrison et al. 2003
    • Barrosa¬
    • Barrosa¬ Order Artiodactyla (Even-toed ungulates) 3 groups: 1. Suiformes (pigs, peccaries, hippopotamuses), 2. Tylopoda (camels, llamas) 3. Ruminantia (cattle, goats, sheep, deer, antelopes, giraffes) 9 families (13 tribes) including Bovidinae  Family Bovidae  c. 137 species  Last species (new genus) discovered in 1992
    • Domestic pig Sus scrofa domestica Centromeric satellites METACENTRIC CLONES: GC rich centromeric heterochromatin • Clone pAL7.5 (“Al”): present in all metacentric chromosomes (SSC1 – SSC12 and X ); 294bp • Clone pAv1.5 (“Av”): present only in SSC1; 313bp ACROCENTRIC CLONES: AT rich centromeric heterochromatin • Clone pMb3.5 (“3.5”): present in all acrocentrics (SSC13-SSC18); 309bp Karyotype: Jantsch et al., 1990
    • Domestic pig Sus scrofa domestica Centromeric satellites METACENTRIC CLONES: GC rich centromeric heterochromatin diverse ACROCENTRIC CLONES: AT rich centromeric heterochromatin homogeneous Bouquet at meiotic pachytene promotes clustering of acrocentric centromeres and homogeneisation Schwarzacher et al., 1984
    • XY SSC1 The synaptonemal complex at meiotic pachytene SCP1: central element protein FISH probe for centromere of chromosome 1 SSC1 Defria and Schwarzacher 2014 Diagram: 2004 Page and Hawley
    • Acrocentric chromosomes cluster and are associated via their repetitive DNA sequences not the SC itself SSC1 Ac Ac Ac Ac Ac Ac SCP1: central element protein FISH probe for centromeres of all Ac and SSC1 Alnajar and Schwarzacher 2010
    • DNA methylation Immunostaining with anti-SCP1 (red) and anti-methyl-5-cytosine (green) on SC spreads. The methylation signal is amplified towards ends of the chromosomes (yellow tips) and more methylation occurs in the chromatin loops.
    • The Ac chromocentre stains strongly with DAPI and is not methylated 5MeC Mc1 5MeC Ac2Sheperd and Schwarzacher 2013 (unpub.) conventionally spread pachytene nuclei
    • Sheep satellite I OaSatI
    • Sheep satellite I OaSatI
    • Hughes and Heslop-Harrison 2014 BtSatI homology in sheep 73.6%
    • Dotplot of bovine satellite I against a region of goat chromosome 5 Dotplot of ovine satellite I repetitive unit against a region of goat chromosome 10
    • BtSatI BtSatIV Gaspar, Hughes, Chaves and Schwarzacher 2014 FISH on cattle (Brakman) chromosomes
    • Satellite I and II collocalize, Satellite IV has separate arrays BtSatII BtSatI BtSatII BtSatIV Gaspar and Schwarzacher 2014
    • pBtKB 5 BtSatI-2 BtSatI-4
    • SINE A2/tA is part of Satellite IV and hybridizes to euchromatin and centromeric heterochromatin
    • SINE A2/tA is part of Satellite IV and hybridizes to euchromatin and centromeric heterochromatin  But it is outcompeted when hybridized together with SatIV probe and appears on euchromatin only
    • Conventional and synaptonemal complex spread of male sheep BtSatII Cluster of some acrocentric centromeres BtSatII Schwarzacher, Chaves, Heslop-Harrison & students 2014
    • Cattle Sat I organisation Clone pBtKB5 is part of BtSatI and indicates subrepeats and higher order structures Hughes and Heslop-Harrison 2014; Chaves et al 2004 Chromosome Research 94.3%.
    • BtSatI homology between cattle and sheep Laetita Gaspar Pairwise identity 54.7%
    • Satellite I Satellite II Satellite III Satellite IV SINE A2/tA A element Cattle Sheep Cattle Sheep Cattle Sheep Cattle Sheep Shared by ruminants. Density Gradient (g/cm3) 1.715 1.714 1.723 1.723 1.706 X 1.709 X Length (bp) 1402 820 700 700 X X 3808 X Pairwise identity (%) 54.7 % 61.3% X X
    • BtSatI homology in goat Hughes and Heslop-Harrison 2014 60.3%
    • 1.715 satellite I Divergence between cattle and sheep/goat Less cross hybridization in FISH experiments But strong homogeneisation within each species acrocentric association during meiosis
    • Tandemly repeated satellite DNA in the Artiodactyla Pat Heslop-Harrison phh4@le.ac.uk www.molcyt.com Trude Schwarzacher & Raquel Chaves Molecular cytogenetic approaches build a full picture of the behaviour of chromosomes (translocations/fusions) and satellite DNA organization and evolution Current sequencing methods are unable to assemble the sequences blocks or cope with chromosomal rearrangements