Optical coherence tomography (OCT) with unprecedented submicrometer axial resolution achieved by use of a photonic crystal fiber in combination with a compact sub-10-fs Ti:sapphire laser (Femtolasers Produktions) is demonstrated for what the authors believe is the first time. The emission spectrum ranges from 550 to 950 nm (lambda(c)=725 nm , P(out)=27 mW) , resulting in a free-space axial OCT resolution of ~0.75 mum , corresponding to ~0.5 mum in biological tissue. Submicrometer-resolution OCT is demonstrated in vitro on human colorectal adenocarcinoma cells HT-29. This novel light source has great potential for development of spectroscopic OCT because its spectrum covers the absorption bands of several biological chromophores.

In horses, graying with age is an autosomal dominant trait associated with a high incidence of melanoma and vitiligo-like depigmentation. Here we show that the Gray phenotype is caused by a 4.6-kb duplication in intron 6 of STX17 (syntaxin-17) that constitutes a cis-acting regulatory mutation. Both STX17 and the neighboring NR4A3 gene are overexpressed in melanomas from Gray horses. Gray horses carrying a loss-of-function mutation in ASIP (agouti signaling protein) had a higher incidence of melanoma, implying that increased melanocortin-1 receptor signaling promotes melanoma development in Gray horses. The Gray horse provides a notable example of how humans have cherry-picked mutations with favorable phenotypic effects in domestic animals.

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