[DIYbio] Re: Yeast chromosome numbers minimized using genome editing

https://www.nature.com/articles/d41586-018-05309-4

There are reports showing that chromosomes can be fused but its results are preliminary

The genomes of nucleus-bearing organisms are divided into linear chromosomes. The number of chromosomes ranges from one to hundreds across species. But why is there such variation? Do specific chromosome numbers hold an advantage for particular species? In two papers in Nature, Shao et al.1 and Luo et al.2 independently manipulate the genome of the budding yeast Saccharomyces cerevisiae by systematically fusing chromosomes, enabling the researchers to explore the consequences of chromosome-number reduction.

 Normal S. cerevisiae genomes have 16 distinct chromosomes (n = 16), which range from 230 to 1,532 kilobases in length3. To function correctly, yeast chromosomes need protective structures called telomeres at both ends, and only one centromere — a region that ensures the accurate segregation of chromosomes into mother and daughter cells during cell division. Simply fusing the ends of two chromosomes is therefore not a viable strategy for reducing chromosome number because it would produce chromosomes containing two centromeres.

To solve this problem, the two groups used genome-editing tools to fuse sequences found adjacent to one of the telomeres in each chromosome, and to simultaneously remove one of the two centromeres (Fig. 1). Using this approach, they reduced the chromosome number step by step, producing strains that had progressively lower values of n. The fusion strains comprised genomic material that is almost identical to that of normal S. cerevisiae, differing only in chromosome number and by a few non-essential genes that were deleted during strain creation.

https://www.youtube.com/watch?v=nKuJZyZUh2M

Here is the sci show segment on this experiment