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Increased dietary intake of tyrosine upregulates melanin deposition in the hair of adult black-coated dogs

Animal Nutrition 2018年第4期4卷 422-428页

作者： Adrian Watson Jamie Wayman Russell Kelley AlexANDre Feugier Vincent Biourge Royal Canin Research Centre 30470 AimarguesFrance Royal Canin Pet Health Nutrition Center LewisburgOH 45338USA

The principle determinant of melanin derived hair colour and patterning in mammals is genetic, but environmental factors are now thought to play a role. It has been shown that the concentration of melanins in cat hair is influenced by the amino acid composition of their diets. Also, puppies were found to require tyrosine(Tyr) intake significantly greater than that recommended for normal growth and development in order to optimize melanin expression in their coats. Much of the work to date has been conducted in growing animals. Less is known about the relationship between nutrition and hair melanin deposition in healthy adult animals. In this study, we fed 2 groups of adult black Labrador retrievers(12 dogs/group) different concentrations of Phe + Tyr(5.6 vs. 3.5 g/Mcal) for 24 weeks and used spectrophotometric measurements every 8 weeks to detect any associated changes in the dogs' hair colour.The higher intake dogs showed reduced dilution of their black coat pigment compared with the lower intake dogs. Specifically, following 16 weeks at the higher intake, the dogs showed less yellow pigmentation to their coats(P = 0.0032), and after 24 weeks at the higher intake, the dogs showed less red(P < 0.0001) and yellow(P< 0.0001), as well as greater overall dark pigmentation(P < 0.0001). In conclusion, we have demonstrated for the first time that colour expression in the hair-coat of adult dogs is dependent on dietary intake of Tyr, and that the requirement appears to be in excess of the minimum level recommended to maintain health.

关键词： Canine Phenylalanine Amino acids Hair colour Eumelanin pheomelanin

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Isolation and Characterization of Melanin Pigment from Yesso Scallop Patinopecten yessoensis

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Journal of Ocean University of China 2017年第2期16卷 279-284页

作者： SUN Xiujun WU Biao ZHOU Liqing LIU Zhihong DONG Yinghui YANG Aiguo Yellow Sea Fisheries Research Institute Chinese Academy of Fishery Sciences College of Biological and Environmental Sciences Zhejiang Wanli University

Melanin is one of the essential compounds in the pigments of molluscan shells.However,the effects of melanin on color variations in molluscs are largely unknown.Our previous study suggests that Yesso scallop Patinopecten yessoensis might contain melanin pigment in the dark brown shell.We therefore isolated melanin from the pigmented shells using hydrochloric acid method,and characterized the types of melanin pigments by spectrophotometry.The purified melanin,which was verified by spectrophotometry scanning and HPLC analysis,showed the typical characteristics of melanin absorption spectra and HPLC chromatograms.The contents of pheomelanin and eumelanin in pigmented shells,which were determined by the linear standard curve of melanin at 405 nm and 350 nm absorbance,were 48.23 ? 1.350 and 157.65 ? 5.905 mg,respectively.The present results indicate that the brown-pigmented shells of scallops comprise approximately 76.6% of eumelanin and 23.4% of pheomelanin,which supports the presence of eumelanin-rich pigment in scallop shells.Therefore,the combination of hydrochloric acid extraction and spectrophotometric quantification is a rapid and efficient method to isolate and quantify melanin in shells.This will facilitate the melanin studies related to shell color polymorphism and the selective breeding of bivalves with different shell colors.

关键词： eumelanin pheomelanin hydrochloric acid method spectrophotometry

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