Transgenic mouse offspring generated by ROSI.

The production of transgenic animals is an important tool for experimental and applied biology. Over the years, many approaches for the production of transgenic animals have been tried, including pronuclear microinjection, sperm-mediated gene transfer, transfection of male germ cells, somatic cell nuclear transfer and the use of lentiviral vectors. In the present study, we developed a new transgene delivery approach, and we report for the first time the production of transgenic animals by co-injection of DNA and round spermatid nuclei into non-fertilized mouse oocytes (ROSI).

Relationship between non-return rate and chromatin condensation of deep frozen bull spermatozoa.

This study analyzes the relationship between chromatin condensation and field fertility, expressed as 90 days non-return rate (NRR), of bulls actively used by AI studs. Frozen-thawed semen from five bulls (six ejaculates per bull, three straws per ejaculate), that showed a non-return rate between 60 and 80%, were analyzed to assess sperm chromatin condensation and stability. The chromatin condensation was determined by flow cytometry using propidium iodide as fluorochrome, and the chromatin stability was evaluated by inducing its decondensation with SDS and EDTA.