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Summary Based on the sample in this study (members of the Spina Bifida Association of America), there are approximately 2.15 times as many mothers with Rh-blood type than would be expected in a similar sized sample of the general population. 相似文献
304.
P. C. Baker K. M. Hoff R. E. Buda 《Cellular and molecular life sciences : CMLS》1978,34(11):1521-1522
Summary
Xenopus larvae raised from stage 21 in melatonin solution and upon a dark background had fewer head melanophores at stage 48 than control animals not exposed to melatonin. Rearing larvae in melatonin solution seems to mimic rearing larvae on a light background. 相似文献
305.
Summary Aeration extracts from femaleDacus cucurbitae and femaleDacus dorsalis have been shown to contain a variety of 2,8-dialkyl-1, 7-diaxospiro [5.5] undecanes together with N-3-methylbutylacetamide. 相似文献
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Influence of seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales 总被引:4,自引:0,他引:4
C S Baker S R Palumbi R H Lambertsen M T Weinrich J Calambokidis S J O'Brien 《Nature》1990,344(6263):238-240
Humpback whales (Megaptera novaeangliae) migrate nearly 10,000 km each year between summer feeding grounds in temperate or near-polar waters and winter breeding grounds in shallow tropical waters. Observations of marked individuals suggest that major oceanic populations of humpback whales are divided into a number of distinct seasonal subpopulations which are not separated by obvious geographic barriers. To test whether these observed patterns of distribution and migration are reflected in the genetic structure of populations, we looked for variation in the mitochondrial DNA of 84 individual humpback whales on different feeding and wintering grounds of the North Pacific and western North Atlantic oceans. On the basis of restriction-fragment analysis, we now report a marked segregation of mitochondrial DNA haplotypes among subpopulations as well as between the two oceans. We interpret this segregation to be the consequence of maternally directed fidelity to migratory destinations. 相似文献
309.
In earlier studies of central nervous fibre tracts, it was tacitly assumed that individual axons are relatively uniform along their length. In the retinofugal pathway in particular, axon diameter, myelin thickness and correlated conduction properties have been treated as constant throughout the optic nerve, chiasm and tract. We report here that the conduction velocities of fibres contributing to the early components of the compound action potential are significantly greater in the optic tract than in the optic nerve of ferrets, and also that the diameters of the largest retinofugal fibres increase from nerve to tract. This observation raises significant questions about the developmental mechanisms in the central nervous system that relate the axons, their diameters, and the glia with which they are myelinated. In addition, it indicates that studies that have relied on the constancy of conduction velocity along the retinofugal course may require reappraisal. 相似文献
310.
CREBBP mutations in relapsed acute lymphoblastic leukaemia 总被引:2,自引:0,他引:2