NANYUKI, Kenya (AP) — Groundbreaking work to keep alive the nearly extinct northern white rhino subspecies by in-vitro fertilization has been hampered by travel restrictions due to the coronavirus. And time is running out. The two remaining northern white rhinos are female. The goal is to create viable embryos in a lab by inseminating their eggs with frozen sperm from dead males, then transfer them into a surrogate mother, a southern white rhino. As of January, three embryos had been created and stored in liquid nitrogen. But further key steps are now on hold.