Mitotic monkey business

Attempts to obtain non-human primate clones have been unsuccessful so far. In April 11 Science, Calvin Simerly and colleagues at the University of Pittsburgh School of Medicine, Pennsylvania, US, show that the difficulties may lie in fundamental problems in cell division after nuclear transfer that hampers both embryonic stem cell production and reproductive cloning (Science, 300:297, April 11, 2003).

Simerly et al. studied the outcome of somatic and embryonic cell nuclear transfer in 716 rhesus macaques oocytes. Although the nuclear transfers looked normal, the implant of 33 embryos in surrogates resulted in no pregnancies. To identify the molecular obstacles responsible for this failure, they used imaging and immunochemical techniques to examine basic embryonic cell structures and proteins. DNA and microtubule imaging showed disarrayed mitotic spindles with misaligned chromosomes. In addition, two of the key proteins involved in spindle pole assembly and functioning — NuMA and HSET — were absent after ...