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111.
Intra‐cohort cannibalism is an example of a size‐mediated priority effect. If early life stages cannibalize slightly smaller individuals, then parents face a trade‐off between breeding at the best time for larval growth or development and predation risk from offspring born earlier. This game‐theoretic situation among parents may drive adaptive reproductive phenology toward earlier breeding. However, it is not straightforward to quantify how cannibalism affects seasonal egg fitness or to distinguish emergent breeding phenology from alternative adaptive drivers. Here, we devise an age‐structured game‐theoretic mathematical model to find evolutionary stable breeding phenologies. We predict how size‐dependent cannibalism acting on eggs, larvae, or both changes emergent breeding phenology and find that breeding under inter‐cohort cannibalism occurs earlier than the optimal match to environmental conditions. We show that emergent breeding phenology patterns at the level of the population are sensitive to the ontogeny of cannibalism, that is, which life stage is subject to cannibalism. This suggests that the nature of cannibalism among early life stages is a potential driver of the diversity of reproductive phenologies seen across taxa and may be a contributing factor in situations where breeding occurs earlier than expected from environmental conditions. 相似文献
112.
《Cell reports》2020,30(5):1342-1357.e4
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113.
Alexander V. Kirdyanov Eugene A. Vaganov Malcolm K. Hughes 《Trees - Structure and Function》2007,21(1):37-44
We propose a technique for separating the climatic signal which is contained in two tree-ring parameters widely used in dendroclimatology.
The method is based on the removal of the relationship between tree-ring width (TRW) and maximum latewood density (MXD) observed
for narrow tree rings from high latitudes. The new technique is tested on data from three larch stands located along the northern
timberline in Eurasia. Correlations were calculated between the temperatures of pentads (five consecutive days), TRW chronologies
and MXD chronologies calculated according to the standard and proposed methods. The analysis confirms the great importance
of summer temperature for tree radial growth and tree-ring formation. TRW is positively correlated with the temperature of
four to eight pentads (depending on the region) at the beginning of the growth season, but MXD as obtained by the standard
technique is correlated with temperature over a much longer period. For maximum density series from which the relationship
between MXD and TRW has been removed (MXD′), there is a clear correlation with temperatures in the second part of the growing
season. These results are consistent with the known dynamics of tree-ring growth in high latitudes and mechanisms of tree-ring
formation. 相似文献
114.
115.
Astrid Schöna 《FEMS microbiology reviews》1999,23(3):391-406
Ribonuclease P is the endonuclease required for generating the mature tRNA 5'-end. The ribonucleoprotein character of this enzyme has now been proven in most organisms and organelles. Exceptions, however, are still the chloroplasts, plant nuclei and animal mitochondria where no associated RNAs have been detected to date. In contrast to the known RNA subunits, which are fairly well-conserved in size and structure among diverse phylogenetic groups, the protein contribution to the holoenzyme is highly variable in size and number of the individual components. The structure of the bacterial protein component has recently been solved. In contrast, the spatial arrangement of the multiple subunits in eukaryotic enzymes is still enigmatic. Substrate requirements of the enzymes or their catalytic RNA subunits are equally diverse, ranging from simple single domain mimics to an almost intact three-dimensional structure of the pre-tRNA substrate. As an example for an intermediate in the enzyme evolution, ribonuclease P from the Cyanophora paradoxa cyanelle will be discussed in more detail. This enzyme is unique, as it combines cyanobacterial and eukaryotic features in its function, subunit composition and holoenzyme topology. 相似文献
116.
117.
Charles E. Wenner John C. Cheney L. David Tomei 《Journal of cellular biochemistry》1981,15(2):161-168
The introduction of either PGF2α (10?7 M) or TPA (10?7 M) stimulated, ouabain-sensitive 86Rb+ influx at 30 min in postconfluent 3T3-4 mouse fibroblast cultures by 117% and 124%, respectively. Both TPA and PGF2α at these concentrations stimulated the incorporation of 3H-TdR into DNA. TPA had the greatest stimulatory effect, which was similar to that obtained with 10% fetal calf serum. In accord with the idea that modulation of membrane processes such as Na+/K+ pump activity in fibroblasts may reflect important events related to the initiation of DNA synthesis, it was observed that in both 3T3-4 and C3H-1 0T½ cells there were parallel increases in 3H-TdR incorporation and ouabain-sensitive 86Rb+ influxes with 10?7 M TPA, whereas PGF2α stimulated a significant increase in 3H-TdR incorporation in 3T3-4 but not C3H-10T½ cells and only marginal increases in ouabain-sensitive 86Rb+ influx in both. Therefore, although there appears to be a close correlation between Na+/K+ pump activation and subsequent S-phase entry following TPA stimulation, a similar correlation for PGF2α cannot be confirmed. 相似文献
118.
119.
《Developmental cell》2022,57(18):2221-2236.e5
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120.
The distribution of vitamin K epoxidase activity in rough and smooth microsomes has been studied and compared to the prothrombin precursor and vitamin K-dependent carboxylase activity. All three activities were high in rough microsomes as compared to the low levels found in smooth microsomes. The results are in agreement with the suggestion that there might be a linkage between the vitamin K-dependent carboxylation and epoxidation reaction in vivo. 相似文献