Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish-brown pheomelanins. They can be quantified by HPLC analysis of pyrrole-2,3,5-tricarboxylic acid (PTCA) and aminohydroxyphenylalanine (AHP). We recently developed a spectrophotometric method for assaying the total amount of eu- and pheomelanins by dissolving melanins in Soluene-350 plus water. In this study, we examined whether absorbance at 500 nm (A500) of the Soluene-350 solution reflects the total amount of melanins obtained by the HPLC methods, and whether the ratio of absorbances between 650 and 500 nm reflects the eumelanin/total melanin ratio in mouse hair, sheep wool, and human hair. Our findings were as follows: (1) Total melanin levels calculated from A500 values correlate well with those obtained from PTCA and AHP values by multiplying with the following factors: for mice, PTCA x 45 + AHP x 2.5; for sheep, PTCA x 40 + AHP x 15; and for humans, PTCA x 160 + AHP x 10. (2) The A650/ A500 ratios were higher (0.25-0.33) in black to brown hair while they were significantly lower (0.10-0.14) in yellow to red hair. These results indicate that (1) the A500 value can be used to quantify the total combined amount of eu- and pheomelanins, and (2) the A650/A500 ratio can serve as a parameter to estimate the eumelanin/total melanin ratio. The present method provides a convenient way to qualitatively characterize eu- and pheomelanins in melanins produced in follicular melanocytes.

Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish pheomelanins. Melanogenesis is influenced by a number of genes, the levels of whose products determine the quantity and quality of the melanins produced. To examine the effects of various coat-color genes on the chemical properties of melanins synthesized in the follicular melanocytes of mice, we have introduced new methods to solubilize differentially pheomelanins and brown-type eumelanins. We applied these and previously developed high-performance liquid chromatography and spectrophotometric methods for assaying eu- and pheomelanins to characterize melanins in various mutant mice: black, lethal yellow, viable yellow, agouti, brown, light, albino, dilute, recessive yellow, pink-eyed dilution, slaty, and silver. It was demonstrated that 1) complete solubilization of melanins in Soluene-350 is a convenient method to estimate the total amount of eu- and pheomelanins, 2) lethal yellow, viable yellow, and recessive yellow hairs contain almost pure pheomelanins, and 3) melanins from brown, light, silver, and pink-eyed black hairs share chemical properties in common that are characterized by partial solubility in strong alkali. We suggest that 1) the brown-type eumelanins have lower degrees of polymerization than the black-type eumelanins, and 2) slaty hair melanin contains a greatly reduced ratio of 5,6-dihydroxyindole-2-carboxylic acid-derived units as compared with black and other eumelanic hair melanins. These results indicate that our methodology, high-performance liquid chromatography and spectrophotometric methods combined, may be useful in chemically characterizing melanin pigments produced in follicular melanocytes.

Melanins are difficult to characterize because of their intractable chemical properties, the heterogeneity in their structural features, and the lack of methods to split melanin polymers into monomer units. To overcome this difficulty, we developed a rapid and sensitive method for quantitatively analyzing eumelanin and pheomelanin in biological samples that is based on the formation of pyrrole-2,3,5-tricarboxylic acid and/or aminohydroxyphenylalanine followed by HPLC determination. The method has been applied to the study of melanogenesis. The results summarized in this review are: 1) Biochemical studies show that in the process of mixed melanogenesis, cysteinyldopas are produced first, which are then oxidized to give pheomelanin; following cysteine depletion, eumelanin is then deposited on the preformed pheomelanin. 2) In vitro and in vivo studies show that tyrosinase activity is the most important factor that regulates the switch of melanogenesis, with lower tyrosinase activities favoring pheomelanogenesis; further suppression of melanogenesis results in a lack of pigment production. 3) In cultured melanocytes, the concentrations of tyrosine and cysteine, and their ratio in the medium, are important in determining the concentrations of eumelanin and pheomelanin produced and their ratio in the cells. In conclusion, our HPLC microanalytical method for characterizing eumelanin and pheomelanin has become a useful tool for the study of melanogenesis.

The Superconducting Submillimeter‐Wave Limb‐Emission Sounder (SMILES) was successfully launched and attached to the Japanese Experiment Module (JEM) on the International Space Station (ISS) on 25 September 2009. It has been making atmospheric observations since 12 October 2009 with the aid of a 4 K mechanical cooler and superconducting mixers for submillimeter limb‐emission sounding in the frequency bands of 624.32–626.32 GHz and 649.12–650.32 GHz . On the basis of the observed spectra, the data processing has been retrieving vertical profiles for the atmospheric minor constituents in the middle atmosphere, such as O3 with isotopes, HCl, ClO, HO2, BrO, and HNO3. Results from SMILES have demonstrated its high potential to observe atmospheric minor constituents in the middle atmosphere. Unfortunately, SMILES observations have been suspended since 21 April 2010 owing to the failure of a critical component.

The two-color (1+1′) threshold photoelectron spectra of naphthalene in a supersonic free jet have been recorded via nine vibronic levels of the S1 electronic state up to about 1420 cm−1 above the S1 band origin. The threshold photoelectron spectra recorded via the S1 band origin and via totally symmetric ag vibronic levels show significant intensity in Δν=+1 transitions in nontotally symmetric vibrations having b1g symmetry indicating that the ionization transition gains significant intensity through a vibronic coupling mechanism between the two lowest doublet cationic states. The strongest departure from the expected Δν=0 propensity in the threshold photoelectron spectra occurs through excitation of the totally symmetric 8 mode having ag symmetry indicating that a considerable displacement occurs along the normal coordinate of this 8 mode upon ionization from the S1 state. The superior resolution of the threshold photoelectron technique over conventional photoelectron methods has allowed accurate values for the fundamental vibrational frequencies of naphthalene in its ground cationic state to be determined and it has also allowed a more rigorous investigation of the vibronic coupling mechanism that occurs between the two lowest doublet cationic states. Moreover, an improved value for the adiabatic ionization energy of naphthalene of 65 687±7 cm−1 (8.1442±0.0009 eV) has been determined.