Phenotype Image Detail

Image

Caption

Morphology of melanosomes observed in primary cultures of skin-derived melanocytes from wild-type (Pmel^+/+) and Pmel^tm1.1Sson/Pmel^tm1.1Sson (Pmel^-/-) mice. (A) Bright-field microscopy; scale bar, 20 um; inset, 5X magnification. Note that the distribution of melanosomes is similar in both sets of melanocytes. (B) Electron microscopy. Cross-sections of melanosomes in the wild-type (Pmel^+/+) melanocytes are both spherical and rod shaped, whilst they are only spherical in the Pmel^tm1.1Sson/Pmel^tm1.1Sson melanocytes. I, II, III, and IV represent stage I, II, III, and IV melanosomes. M, mitochondria; End, endosomes. Note the presence of fibrillar stage II and III melanosomes in the wild-type melanocytes (panel Bb, marked with arrowheads in inset) in contrast to the granular deposits of melanin in Pmel^tm1.1Sson/Pmel^tm1.1Sson melanosomes (panel Bd, marked with arrows in inset). Bars: 500 nm and 200 nm, in left and right panels respectively (C) Plot of the diameters of melanosomes along the long (length) and short (width) axes measured from electron microscopy images; n>200 for both genotypes. There was a weak correlation between the length and width of melanosomes in wild-type cells (r = 0.52), consistent with their ellipsoidal shape, whereas in Pmel^tm1.1Sson/Pmel^tm1.1Sson cells, there was a strong correlation (r = 0.93), indicating a spherical shape. The difference in the length/width ratio between wild-type and Pmel^tm1.1Sson/Pmel^tm1.1Sson is overwhelmingly significant (Analysis of variance; F = 161, d.f.1 = 1, d.f.2 = 451; P<10^-6).

This image is from Hellstrom AR, PLoS Genet 2011 Sep;7(9):e1002285, and is displayed under the terms of the Creative Commons Attribution 4.0 International License. J:177116

Associated
Alleles

Symbol	Name
Pmel^tm1.1Sson	premelanosome protein; targeted mutation 1.1, Leif Andersson

Associated
Genotypes

Allelic Composition	Genetic Background
Pmel^tm1.1Sson/Pmel^tm1.1Sson	involves: 129S1/Sv * 129X1/SvJ * BALB/c * C57BL/6

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