Chromosome counting in the mouse zygote using low-invasive super-resolution live-cell imaging

Area of Science:

• Embryology
• Genetics
• Biotechnology

Background:

• Abnormal chromosome numbers in preimplantation embryos lead to developmental issues and lower pregnancy rates.
• Current chromosome testing methods require embryo biopsy, which can reduce cell count and pregnancy success.
• Non-invasive methods are needed to assess embryonic chromosomal integrity without compromising viability.

Purpose of the Study:

• To develop a non-invasive method for accurate chromosome counting in mouse embryos.
• To improve chromosome assessment techniques for assisted reproductive technologies (ART).
• To enhance the evaluation of embryonic chromosomal integrity prior to embryo transfer.

Main Methods:

• Initial attempts involved super-resolution live-cell imaging with histone H2B-mCherry mRNA injection.
• A refined method utilized CRISPR/dCas-mediated live-cell fluorescence in situ hybridization (FISH).
• FISH targeted centromere regions for precise chromosome enumeration in mouse embryos.

Main Results:

• Super-resolution imaging with histone H2B-mCherry resulted in underestimation and variability in chromosome counts.
• CRISPR/dCas-mediated FISH provided more accurate chromosome number determination.
• The developed method allows for non-invasive chromosome counting in early-stage embryos.

Conclusions:

• CRISPR/dCas-mediated live-cell FISH is a superior method for accurate, non-invasive chromosome counting in mouse embryos.
• This technique offers potential applications in improving success rates for assisted reproductive technologies in humans and livestock.
• Accurate assessment of chromosomal integrity can guide embryo selection for transfer, reducing developmental failures.