Keith C. Cheng

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Lighter variations of pigmentation in humans are associated with diminished number, size, and density of melanosomes, the pigmented organelles of melanocytes. Here we show that zebrafish golden mutants share these melanosomal changes and that golden encodes a putative cation exchanger slc24a5 (nckx5) that localizes to an intracellular membrane, likely the(More)
Human skin pigmentation shows a strong positive correlation with ultraviolet radiation intensity, suggesting that variation in skin color is, at least partially, due to adaptation via natural selection. We investigated the evolution of pigmentation variation by testing for the presence of positive directional selection in 6 pigmentation genes using an(More)
Mutations caused by oxidative DNA damage may contribute to human disease. A major product of that damage is 8-hydroxyguanine (oh8Gua). Because of differences in experimental design, the base pairing specificity of oh8G in vivo is not completely resolved. Here, oh8dGTP and DNA polymerase were used in two complementary bacteriophage plaque color assays to(More)
Maple syrup urine disease (MSUD) is an inherited disorder of branched-chain amino acid metabolism presenting with life-threatening cerebral oedema and dysmyelination in affected individuals. Treatment requires life-long dietary restriction and monitoring of branched-chain amino acids to avoid brain injury. Despite careful management, children commonly(More)
Zebrafish have become a widely used model organism in developmental biology research. In order to initiate an experimental foundation for aging studies, we have determined some basic gerontological parameters for populations of outbred zebrafish, and the golden sparse strain. Outbred zebrafish manifested a mean life span of about 42 months, with the longest(More)
We have identified a cohort of zebrafish expressed sequence tags encoding eight Na,K-ATPase alpha subunits and five beta subunits. Sequence comparisons and phylogenetic analysis indicate that five of the zebrafish alpha subunit genes comprise an alpha1-like gene subfamily and two are orthologs of the mammalian alpha3 subunit gene. The remaining alpha(More)
Glutaric acidemia type I (GA-I) is an inherited disorder of lysine and tryptophan metabolism presenting with striatal lesions anatomically and symptomatically similar to Huntington disease. Affected children commonly suffer acute brain injury in the context of a catabolic state associated with nonspecific illness. The mechanisms underlying injury and(More)
Genetic information in forensic studies is largely limited to CODIS data and the ability to match samples and assign them to an individual. However, there are circumstances, in which a given DNA sample does not match anyone in the CODIS database, and no other information about the donor is available. In this study, we determined 75 SNPs in 24 genes(More)
In the autosomal recessive human disease, glutaric aciduria type I (GA-1), glutaryl-CoA dehydrogenase (GCDH) deficiency disrupts the mitochondrial catabolism of lysine and tryptophan. Affected individuals accumulate glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA) in the serum and often suffer acute striatal injury in childhood. Prior attempts to(More)
PTEN is a tumor suppressor gene associated with multiple tumor types. PTEN function is essential for early embryonic development and is involved in the regulation of cell size, number, and survival. By dephosphorylating PIP(3), PTEN normally acts to inhibit the PI3-Kinase/AKT pathway. Here we have identified two zebrafish orthologs, ptena and ptenb, of the(More)