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排序方式: 共有698条查询结果,搜索用时 15 毫秒
91.
92.
Reviews in Fish Biology and Fisheries - 相似文献
93.
Ornithine Decarboxylase Activity in Brain Regulated by a Specific Macromolecul, the Antizyme 总被引:1,自引:0,他引:1
Paivi H. Laitinen Riitta-Liisa Huhtinen Oili A. Hietala Antti E. I. Pajunen 《Journal of neurochemistry》1985,44(6):1885-1891
Mouse brain ornithine decarboxylase activity is about 70-fold higher at the time of birth compared with that of adult mice. Enzyme activity declines rapidly after birth and reaches the adult level by 3 weeks. Immunoreactive enzyme concentration parallels very closely the decrease of enzyme activity during the first postnatal week, remaining constant thereafter. The content of brain antizyme, the macromolecular inhibitor to ornithine decarboxylase, in turn is very low during the first 7 days and starts then to increase and at the age of 3 weeks it is about six times the level of that in newborn mice. This may explain the decrease in enzyme activity during brain maturation, and suggests the regulation of polyamine biosynthesis by an antizyme-mediated mechanism in adult brain. 相似文献
94.
Leaching losses of nitrogen from a clay soil under grass and cereal crops in Finland 总被引:1,自引:0,他引:1
Antti Jaakkola 《Plant and Soil》1984,76(1-3):59-66
Summary A 16-plot experimental field was established in 1975 on a clay soil in Jokioinen, Finland. The water discharge through tile drains was measured and its ammonium and nitrate N contents determined for each plot separately. The surface runoff was also measured and analysed. The annual runoff and the N leached from the surface of moderately fertilized (100 kg/ha/y N) cereal plots varied during 1976–1982 from 21 to 301 mm and from 2 to 7 kg/ha, respectively. The discharge of water and leaching of N through subdrains varied from 65 to 225 mm and from 1 to 38 kg/ha, respectively. The highest leaching was probably caused by a previous fallow. The annual N uptake by the crop varied between 41 and 122 kg/ha.Of the fertilizer-N used for cereals, 20% of that applied in the autumn was lost, but only 1 to 4 per cent was lost when applied in the spring. There was much less N leaching from ley than from barley plots, although the former was given twice as much N. The rate of N fertilization had only a very slight effect on N leaching from both ley and barley plots.The results were compared with those obtained in lysimeters filled with clay, silt, sand and peat soils. No definite conclusions can be drawn because the lysimeter experimental data are only for the first year. 相似文献
95.
96.
Adil Mardinoglu Hao Wu Elias Bjornson Cheng Zhang Antti Hakkarainen Sari M. Räsänen Sunjae Lee Rosellina M. Mancina Mattias Bergentall Kirsi H. Pietiläinen Sanni Söderlund Niina Matikainen Marcus Ståhlman Per-Olof Bergh Martin Adiels Brian D. Piening Marit Granér Nina Lundbom Jan Borén 《Cell metabolism》2018,27(3):559-571.e5
97.
98.
Patrick Jern Antti Kärnä Janna Hujanen Tatu Erlin Annika Gunst Helmi Rautaheimo Emilia Öhman S. Craig Roberts Brendan P. Zietsch 《Evolution and human behavior》2018,39(4):373-379
A number of recent studies have implicated that incongruent use of hormonal contraceptives (HCs) negatively affects various aspects of women's romantic relationships. It has been suggested that women with incongruent HC use (a discrepancy in HC use status between when they first met their current partner and the time of study participation) report less sexual satisfaction and higher jealousy scores compared to women with congruent HC use. A similar effect has also been hypothesized for general relationship satisfaction, and recent findings suggest that the association between HC incongruency and women's general relationship satisfaction is moderated by third-party ratings of facial attractiveness of the women's male partners. Using a large convenience sample (N = 948) of Finnish women, we attempted to replicate previously reported findings but found no support for the HC congruency hypothesis, despite excellent statistical power (≥98.7%) to detect previously reported effect sizes. Instead, after dividing our sample into four groups based on HC congruency/incongruency, we found that the largest differences in jealousy, sexual satisfaction, and relationship satisfaction scores tended to be found between women who were consistent HC users and consistent non-users (i.e., between women with different kinds of congruent HC use). We also detected a significant main effect of current HC use on jealousy. We conclude that HC congruency effects reported in previous studies may have spuriously arisen from unequal distributions of current HC users within congruent and incongruent HC user groups. 相似文献
99.
Congenital adrenal hyperplasia (CAH) due to steroid 21-hydroxylase deficiency is a common inherited defect of adrenal steroid
hormone biosynthesis. Unusually for genetic disorders, the majority of mutations causing CAH apparently result from recombinations
between the CYP21 gene encoding the 21-hydroxylase enzyme and the closely linked, highly homologous pseudogene CYP21P. The
CYP21 and CYP21P genes are located in the major histocompatibility complex class III region on chromosome 6p21.3. We analyzed
the mutations and recombination breakpoints in the CYP21 gene and determined the associated haplotypes in 51 unrelated Finnish
families with CAH. They represent no less than half of all CYP21 deficiency patients in Finland. The results indicate the
existence of multiple founder mutation-haplotype combinations in the population of Finnish CAH patients. The three most common
haplotypes constituted half of all affected chromosomes; only one-sixth of the haplotypes represented single cases. Each of
the common haplotypes was shown consistently to carry a typical CYP21 mutation and only in some cases was additional variation
observed. Surprisingly, comparisons with previous published data revealed that several of the frequent mutation-haplotype
combinations in Finland are in fact also found in many other populations of patients of European origin, thus suggesting that
these haplotypes are of ancient origin. This is in clear contrast to many reports, including the present one, where a high
frequency of de novo mutations in the CYP21 gene has been reported. In addition, two unique sequence aberrations in CYP21
(W302X and R356Q), not known to exist in the CYP21P pseudogene, were detected.
Received: 5 September 1996 / Revised: 11 November 1996 相似文献
100.
Marko T Korhonen Alexander Cristea Markku Alén Keijo H?kkinen Sarianna Sipil? Antti Mero Jukka T Viitasalo Lars Larsson Harri Suominen 《Journal of applied physiology》2006,101(3):906-917
Biopsy samples were taken from the vastus lateralis of 18- to 84-yr-old male sprinters (n = 91). Fiber-type distribution, cross-sectional area, and myosin heavy chain (MHC) isoform content were identified using ATPase histochemistry and SDS-PAGE. Specific tension and maximum shortening velocity (V(o)) were determined in 144 single skinned fibers from younger (18-33 yr, n = 8) and older (53-77 yr, n = 9) runners. Force-time characteristics of the knee extensors were determined by using isometric contraction. The cross-sectional area of type I fibers was unchanged with age, whereas that of type II fibers was reduced (P < 0.001). With age there was an increased MHC I (P < 0.01) and reduced MHC IIx isoform content (P < 0.05) but no differences in MHC IIa. Specific tension of type I and IIa MHC fibers did not differ between younger and older subjects. V(o) of fibers expressing type I MHC was lower (P < 0.05) in older than in younger subjects, but there was no difference in V(o) of type IIa MHC fibers. An aging-related decline of maximal isometric force (P < 0.001) and normalized rate of force development (P < 0.05) of knee extensors was observed. Normalized rate of force development was positively associated with MHC II (P < 0.05). The sprint-trained athletes experienced the typical aging-related reduction in the size of fast fibers, a shift toward a slower MHC isoform profile, and a lower V(o) of type I MHC fibers, which played a role in the decline in explosive force production. However, the muscle characteristics were preserved at a high level in the oldest runners, underlining the favorable impact of sprint exercise on aging muscle. 相似文献