Creating a functional single- chromosome yeast Shao Y., et. al. - - PowerPoint PPT Presentation

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Creating a functional single- chromosome yeast Shao Y., et. al. - - PowerPoint PPT Presentation

Mar 20, 2023 138 likes •429 views

Creating a functional single- chromosome yeast Shao Y., et. al. (2018). Nature April Rich 3/2/2020 1 Whats in a number? Myrmecia pilosula Polyommatus atlantica n=1 n=224 2 https://en.wikipedia.org/wiki/Jack_jumper_ant Credit: Raniero

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Creating a functional single- chromosome yeast

Shao Y., et. al. (2018). Nature

April Rich 3/2/2020

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What’s in a number?

Polyommatus atlantica

n=224

Myrmecia pilosula

n=1

https://en.wikipedia.org/wiki/Jack_jumper_ant Credit: Raniero Panfili

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Protopterus aethiopicus

132 Gb, n=14

Homo sapiens

3.2 Gb, n=23

Credit: George Berninger Jr.

What’s in a number?

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So what's the biological role of chromosome number?

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So what's the biological role of chromosome number?

Saccharomyces cerevisiae

12 Mb, n=16

Credit: Mogana Das Murtey & Patchamuthu Ramasamy

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Liti, G. (2018). Nature news & views

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Fusions

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BY4742/Wt SY0 SY1

16 chromosomes 15 chromosomes: 14 native, 1 fused 14 chromosomes: 12 native, 2 fused

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Fusions

SY6

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9 chromosomes: 2 native, 7 fused

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SY12

4 chromosomes: 0 native, 4 fused

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Fusions

SY12 SY13 SY14

3 chromosomes: 0 native, 3 fused 2 chromosomes: 0 native, 2 fused 1 chromosomes: 0 native, 1 fused!

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SY14 - single chromosome strain

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XVI V VI XIV XII XII XV XI II I IV VII VIII X IX III

  • Deleted roughly 0.2 Mb
  • Single chromosome is 8x longer than longest native chromosome
  • 1 centromere for 11.8 Mb
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Fusion validation

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Fusion validation

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SY2: fusion of I & II

II I

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Genome sequence

  • Overall nucleotide sequence ordering preserved in SY14 fusion strain
  • Fusion Introduced 11 SNPs and 7 indels

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3D structure- HiC

16 native 2 native 7 fused 2 fused 1 fused

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Chr #:

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16 native 2 native 7 fused 2 fused 1 fused

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Directional preference

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Changes in contact

Single fused chromosome lost:

  • 99.6 % of inter-chromosomal contacts
  • 67% of intra-chromosomal contacts

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16 native 2 native 7 fused 2 fused 1 fused

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16 native 2 native 7 fused 2 fused 1 fused

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transcriptome

Only 28 genes, 0.5% of genes, were differentially expressed

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transcriptome

  • loss of adjacent telomere regions
  • strengthening of retained telomere repression
  • stress

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Phenotype

  • Size and shape similar

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Phenotype

  • Size and shape similar
  • Slight reduction in growth rate

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Phenotype

  • Size and shape similar
  • Slight reduction in growth rate
  • Out-competed by WT

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Reproduction

  • Able to mate and produce diploid cells
  • Diploid cells able to produce viable spores
  • 2/6 diploid colonies had aneuploidy after mitosis

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Reproduction

  • Able to mate and produce diploid cells
  • Diploid cells able to produce viable spores
  • 2/6 diploid colonies had aneuploidy after mitosis
  • Mating occurred between the two strains

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So what's the biological role of chromosome number?

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Conclusion

  • SY14 single strain survived
  • Single centromere for 11.8 Mb chromosome was still able to function during

cell division

  • Basically no change in gene expression
  • Similar growth and phenotype to wild type
  • 2/6 colonies tendency to form polyploidy- defects in chromosome segregation
  • Reduced gamete production and viability in meiosis

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