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461.
Organic compounds in meteorites seem to have formed by catalytic reactions of CO, H2, and NH3 in the solar nebula, at 360 degrees to 400 degrees K and (4 to 10) x 10-6 atm. The onset of these reactions was triggered by the formation of suitable catalysts (magnetite, hydrated silicates) at these temperatures. These reactions may be a source of prebiotic carbon compounds on the inner planets, and interstellar molecules. 相似文献
462.
Five carbynes (triply bonded allotropes of carbon) have been found by electron diffraction in the Allende and Murchison carbonaceous chondrites: carbon VI, VIII, X, XI, and (tentatively) XII. From the isotopic composition of the associated noble-gas components, it appears that the carbynes in Allende (C3V chondrite) are local condensates from the solar nebula, whereas at least two carbynes in Murchison (C2 chondrite) are of exotic, presolar origin. They may be dust grains that condensed in stellar envelopes and trapped isotopically anomalous matter from stellar nucleosynthesis. 相似文献
463.
Marieke Verleih Alexander Rebl Bernd Köllner Tomáš Korytář Günter Kotterba Eckhard Anders Klaus Wimmers Tom Goldammer 《Fish physiology and biochemistry》2010,36(4):1271-1276
The proline-rich protein 13 (PRR13) is reported to be a key regulator of the resistance to cytostatica by decreasing the copy
number of the proapoptotic gene thrombospondin-1. We isolated and characterized the complete PRR13 gene sequence of rainbow
trout (Oncorhynchus mykiss). The gene comprises four exons and three introns, the latter of comparatively short lengths (100–811 bp). The full-length
PRR13 cDNA consists of 1,101 nucleotides, including an open reading frame of 563 bp, which is predicted to encode a 187 amino
acid protein with a molecular mass of 18.8 kDa. A continuous stretch of ten serine residues at the C-terminus is highly conserved
and characteristic for vertebrate PRR13, but not for other known proline-rich proteins. Phylogenetic analyses suggest a clear
separation of teleostean PRR13 proteins and those from mammalian and reptilian species. Comparison of the tissue-specific
PRR13 mRNA abundance in two strains of the rainbow trout coastal form (TCO Steelhead II-WA vs. BORN Steelhead II-Germany)
revealed an increased expression in the BORN trout in nearly all examined tissues. The major expression differences were detected
in gill (2.29-fold) and in liver tissue (2.16-fold). Hence, the increased PRR13 expression in BORN trout might cause improved
protection from natural cytostatica and therefore support our assumption that PRR13 is a candidate gene possibly involved
in the varying ability of the two rainbow trout strains to handle environmental stress under local conditions of the Southern
Baltic. 相似文献
464.
Declan Tobin Esa A. Mäntysaari Dominic F. Houlihan Anders Kiessling Krisna Rungruangsak-Torrissen Kari Ruohonen 《Aquaculture (Amsterdam, Netherlands)》2006,261(2):510-521
Quantitative genetic analyses of fish composition have been strongly biased towards lipid deposition, rather than protein deposition. This is partly at odds with desires of the modern aquaculture industry, to improve the efficiency of lean growth. Using a quantitative genetic approach, we examined the selection potential in both protein and lipid components of wet weight growth in rainbow trout over a two-year growth period. Two diet treatments were applied to test the hypothesis that an experimental, high protein, low lipid diet (HP) would enhance selection potential compared to the current modern, normal protein, high lipid diet (NP). We found that lipid traits (lipid body weight, percent muscle and body lipid; h2 = 0.40) were more heritable than corresponding protein traits (protein body weight, percent muscle and body protein; h2 = 0.18), indicating a higher selection potential for lipid traits. The results revealed further that breeding for improved lipid composition over the whole growth period is easier than for protein composition. This was shown by the high favourable genetic correlations between differently aged fish for lipid traits. In contrast, the respective correlations for protein traits were low or even negative. Similarly, the genetic correlations between muscle and body composition were higher for lipid than for protein, enhancing selection efforts to change lipid traits. Heritabilities increased with age, implying that selection practiced on old (> 800 g) rather than young (< 60 g) fish should be more effective in achieving a compositional response. Although the diet had a significant effect on the composition traits, there was no general trend for diet differences in heritabilities of either protein or lipid traits. Thus, the hypothesis of increased selection potential on HP diet was not supported. In conclusion, lipid traits are both more variable and exhibit more favourable genetic architecture for selection compared to protein traits. 相似文献