PubMed · 11462380
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
M Nakamura. 2001. [Albinism].. https://pubmed.ncbi.nlm.nih.gov/11462380/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Abundant evidence spanning 25 years demonstrates that hypopigmentation is associated with sensory abnormalities manifested most clearly as elevated absolute dark-adapted thresholds in hypopigmented mice. Here we show that when ocular melanin is increased in the himalayan mouse via alpha-melanocyte stimulating hormone (alpha-MSH) injections, dark-adapted thresholds drop in proportion to the change in ocular melanin. We further measured free calcium concentration with calcium-sensitive microelectrodes in both albino and black mouse retinal eyecups in living subjects. The recordings were done in anesthetized animals as the defect is not present in isolated retinas or in the superfused eye preparation. A double-barreled electrode--pCa and Vref--was used to simultaneously record the calcium concentration and the electroretinogram (ERG) at each of many depths as the electrode was driven through the retina. The position of the electrode was confirmed with ERG and 1,1'-dioctadecyl-3, 3,3',3'-tetramethylindocarbocyanine perchlorate electrode tract reconstruction. Dark-adapted albinos (n = 6) had 1.4 +/- 0.015 mM calcium in the subretinal space compared with 0.80 +/- 0.025 mM in black mice (n = 6). The results of these experiments are consistent with the hypothesis that ocular hypopigmentation causes elevated calcium levels in the subretinal space that in turn mimic light adaptation in hypopigmented mice.
Inhibition of protein synthesis has been shown to affect long-term memory in a wide variety of animal species. But little is known regarding the neuroanatomical location of protein synthesis in different memory tasks. In this study, the effect of intrahippocampal injection of anisomycin, an inhibitor of brain protein synthesis on spatial memory was examined in Morris Water Maze. At first, rats were connulated bilaterally into the CA1 region and then different doses of anisomycin (1.25-2.5 micro g/0.5 micro l) on its vehicle (saline) were injected bilaterally into the CA1 region of rats hippocampus 20 min before training each day. The results showed dose-dependent increases in latencies to find the invisible platform and traveled distances in anisomycin received group compared to the control group. Therefore, it appears that protein synthesis inhibition in the CA1 region of hippocampus impair spatial learning in Morris Water Maze.
The incidence of albinism in Hopi Indians has been estimated as approximately 1 in 200 individuals. It has been suggested that "cultural" selection as the result of a mating advantage of males with albinism has been important in the maintenance of this high incidence. To examine this hypothesis quantitatively, a model that includes male-mating advantage, mutation, and viability selection is analyzed. In order to play an important role in the maintenance of the high incidence of albinism, the necessary mating advantage of males with albinism appears unrealistically high. However, if the extent of viability selection against individuals with albinism is not as large as previously assumed, the necessary amount of mating advantage is not as high. Other related aspects are also discussed here, such as the type of albinism in Hopi Indians and its impact, the conditions for a polymorphism with male-mating advantage and viability selection, and the time necessary to change the incidence of albinism either by the relaxation or institution of male-mating advantage.