Loop size in newt lampbrush chromosomes.

Lampbrush chromosome 11 from the newt Taricha granulosa was studied by scanning electron microscopy (SEM) to determine the size of all loops in this bivalent. Measurements with an XY digitizer revealed a mean loop length of 14.9 microns, with a large standard deviation and a skewed distribution toward higher values.

Supernumerary chromosome variation and heterochromatin distribution in the endemic New Zealand frog Leiopelma hochstetteri.

Specimens of the endemic New Zealand frog Leiopelma hochstetteri from Tapu on North Island were found to have six, nine or ten supernumerary chromosomes in their karyotypes. In comparison with previously published data, these results further indicate probable geographic variation in supernumerary chromosome number between populations. Increased numbers of supernumeraries in these frogs is correlated with apparent decrease of centromeric heterochromatin in the five large metacentric chromosomes of the karyotype, as detected by C-banding.