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排序方式: 共有318条查询结果,搜索用时 15 毫秒
311.
A Haugen 《Virchows Archiv. B, Cell pathology including molecular pathology》1979,29(4):245-252
The cell coat of cultivated fetal rat brain cells as well as malignant rat neurogenic cell lines in culture were studied by transmission electron microscopy with the ruthenium red staining technique. Some of the transformed cell lines demonstrated alteration in the bindng properties of ruthenium red to the cell surface. Otherwise no significant correlation between the visualized cell coat thickness and neoplastic transformation was noted. 相似文献
312.
MHT Hipondoka BCW van der Waal MH Ndeutapo L Hango 《African Journal of Aquatic Science》2018,43(3):199-214
The triangle between the Kavango and Kunene rivers is drained by the Cuvelai, an ephemeral and deltaic drainage system covering more than 100 000 km2. In good rainfall years, the area becomes populated by fish communities dominated by five species migrating southward towards the endorheic Etosha Pan, the basin’s terminal sump. When water dries up, fish subsequently die-off and their sudden appearance in rainy years has captivated scientists for decades. The current study was prompted by hitherto untapped indigenous knowledge through narratives of opportunistic fish harvesting of migrating fish at temporary connections between the Kunene River and the Cuvelai- Etosha Basin. A reconnaissance fish survey in 2017 was complemented by digital satellite images and elevation data analyses. Results support the presence of at least three major ephemeral fish migration routes. The dominant fish genera migrating upstream in Kunene tributaries comprise Enteromius, Oreochromis and Clarias, all eurytopic and known to undertake upstream, lateral and downstream migrations on floodplains. Although other notable fish refugia in the Cuvelai–Etosha Basin are yet to be identified, there is a necessity for the protection and management of these migration routes in tandem with studies on the nature and extent of this inter-basin fish migration under climate change and variability. 相似文献
313.
David A. Haugen 《Analytical biochemistry》1980,103(1):77-80
A contaminant present in reagent grade acetone causes degradation of fluorescent phenolic metabolites of benzo(a)pyrene as measured in the aryl hydrocarbon hydroxylase assay. Although the contaminant was not identified, its properties suggest that it is a relatively volatile organic material, possibly an oxidizing agent. The acetone may be readily purified by distillation. 相似文献
314.
315.
The molecular organization of the beta-globin complex of the deer mouse, Peromyscus maniculatus 总被引:1,自引:0,他引:1
Padgett RW; Loeb DD; Snyder LR; Edgell MH; Hutchison CA d 《Molecular biology and evolution》1987,4(1):30-45
Recombinant DNA clones have been isolated that contain 80 kb of the
beta-globin complex from the deer mouse, Peromyscus maniculatus.
Comparisons of this complex with that from the laboratory mouse, Mus
domesticus (with an order 5'-Hbby, Hbb-bhO, Hbb-bhl, Hbb-bh2, Hbb-bh3,
Hbb-bl, Hbb-b2 3') highlight organizational trends in the beta-globin
complex since the two species diverged. Unlike other mammals studied thus
far, the deer mouse possesses three adult genes. Partial sequence analysis
indicates that each of the three adult genes is intact and hence may be
functional. Hybridization of one of the two Mus pseudogenes, Hbb-bh3, to
genomic blots from Peromyscus reveals that it has a homologous counterpart
in Peromyscus. Homologous genes to the two gamma-like Mus genes, Hbb-bhO
and Hbb-bhl, are also found in Peromyscus. The strong hybridization between
the Hbb-bhl genes and significant nucleotide similarity between the Hbb-bhO
genes suggest that both pairs are important for the ontogeny of these mice
although no known product has been identified for the Hbb-bhO genes. The
presence of Hbb-bhO and Hbb-bhl in Peromyscus suggests that the duplication
that created this related gene set occurred before the two lineages
diverged. A single gene for Hbb-y has been isolated from Peromyscus. The
adult region in Peromyscus has undergone significant divergence from the
same region in Mus, having three rather than two adult genes, the
acquisition of at least 15 kb of extra DNA relative to Mus, and possibly
the loss of the Hbb-bh2 pseudogene. The nonadult region of the complex, in
contrast, contains the same set of genes apparently distributed over the
same amount of DNA as in the Mus beta- globin complex. This observation
suggests that the embryonic region of the complex is more evolutionarily
stable than the adult region.
相似文献
316.
Grayling Thymallus thymallus in Lake Aursjøen, Norway, showed a remarkably uniform growth pattern throughout life, whereas brown trout Salmo trutta showed far more variation. In addition, a narrower age-length interval of maturation was found in grayling. The restricted life history variation in grayling is discussed and it is suggested that all grayling of Lake Aursjøen experience similar environmental conditions as juveniles, which induces low phenotypic variation. In contrast the existence of several spawning populations, adapted to as many as 28 different tributaries, may have created large life history variation in Aursjøen trout. Logistic models revealed that both age and length had significant, simultaneous effects on the maturation of both species. Furthermore, the sexes of trout differed in maturation patterns, i.e. males matured earlier and at smaller sizes than female conspecifics, but no difference was found between the sexes of grayling. In addition, larger sex-specific growth differences were found in trout. An absence of early maturing males in grayling and their presence in trout is discussed as a possible explanation of the restricted life history variation found between sexes of grayling. Male grayling experienced a larger mortality rate than did females, whereas no such differences were found in trout. It is suggested that grayling males invest more in reproduction than do females, due primarily to large investments in breeding behaviour. The equal mortality rates found for both sexes of trout, albeit males starting to spawn earlier than females, is probably explained by a female-selective fishing mortality. 相似文献
317.
318.
A Haugen T Aune 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1986,182(2):277-281
Rabbit pulmonary Clara cells isolated by centrifugal elutriation have been cultured for several weeks. Clara cells generally adhered poorly to plastic but the cells did attach to coated substrates. A selected medium supported serial subculture of Clara cells for 4-5 passages (1:2 split). The medium consisted of a basal nutrient medium, alpha MEM, supplemented with insulin, transferrin, epidermal growth factor, D-glucose, biotin, alpha-tocopherol, pituitary extract, trace elements and 2% Sephadex G-10-filtered FBS. Freshly prepared Clara cells showed high capacity to activate 2-aminofluorene (AF) to mutagenic products. However, after 6 weeks of culture the mutagenic activation of AF was reduced by 92.5% indicating loss of cytochrome P-450. 相似文献