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1.
2.
M. Masuyama 《Biometrical journal. Biometrische Zeitschrift》1991,33(6):725-733
A mathematical model of the linearized growth curve and its physiological interpretation by the introduction of proper age, which is proportional to the chronological age, are presented here. In the second phase, but not in the first phase, this constant of proportionality is highly correlated with the age at menarche. 相似文献
3.
The effects of defoliation treatments on plant growth in sunflower (Helianthus annuus) were studied in the field. Four defoliation treatments, 0 (control), 37.4, 56.1 and 93.4% of the total leaf dry weight,
were applied to plants that had small third leaves. Decreased leaf weight/whole plant weight (F/W) ratios in defoliated plants
rapidly recovered to almost the same ratio as that observed in the control within 12 to 16 days after defoliation according
to the degree of defoliation. The mechanism involved in the recovery of the F/W ratio in defoliated plants mainly consisted
of three parameters: enhancement of (1) carbon distribution ratios in the leaves, (2) photosynthetic activity in the remaining
leaves, and (3) retranslocation of carbon from the stem and/or roots to leaves.
Inhibitive effects of defoliation on relative growth rate and net assimilation rate were seen at an early stage, but subsequently
both rates became larger in defoliated plants than in controls. Defoliated plants tended to show rapid development and expansion
of new leaves, and to show increased specific leaf area and protein synthesis in individual leaves. The sugar content of leaves
in defoliated plants was higher than that in controls, while the content in both stem and roots was lower. These responses
seem to be advantageous for development of the photosynthetic system. Heights of defoliated plants were clearly depressed
according to the degree of defoliation, and this was attributed largely to differences in the elongation rates of the internodes
resulting from defoliation. 相似文献
4.
Noninformative priors for one parameter of many 总被引:4,自引:0,他引:4
5.
Om P. Malhotra Frank Valencic Eric T. Fossel Karl A. Koehler 《Journal of Protein Chemistry》1991,10(1):31-41
Ca2+ titrations of the intrinsic fluorescence of a series of -carboxyglutamic acid (GLA)-deficient bovine prothrombin fragments 1 yield response Hill plot parameters useful for characterization of the metal ion-binding process. 11-, 10-, and 9-GLA fragments 1 exhibitT
m
(the (Ca2+)total concentration at which ln (B/F)=0 in the response Hill plot) values between 0.2 and 0.3 mM. A 22-fold increase inT
m
to 5.4 mM is observed for 8-GLA fragment 1.T
m
decreases to 3.8 mM for the 7- and 6-GLA proteins. The value ofh, about 2.8±0.2 for 11-, 10-, and 9-GLA fragments 1, abruptly decreases to 1.2–1.3 for 8-, 7-, and 6-GLA fragments 1. The observed degree of quenching induced by saturating levels of calcium ions is affected by both changes in the intrinsic fluorescence of the metal ion-free proteins and in the maximum possible degree of quenching in the presence of calcium. The kinetic characteristics of the calcium ion-induced quenching of the intrinsic fluorescence of 6-GLA fragment 1 are identical to those observed in 10-GLA fragment 1, suggesting that the fluorescence quenching observed in the 6- and 10-GLA fragments 1, while different in magnitude, involves similar processes. Observation of an abrupt change in the relative electrophoretic mobilities of 11- to 9-GLA fragments 1 compared to 8- to 6-GLA fragments 1, in the absence or presence of Ca2+, suggests the existence of a major protein conformation change which occurs concomitantly with the noted changes inT
m
andh response Hill plot parameters. Molecular mechanics calculations suggest a structural hypothesis unifying these observations. Central to this model is the presumption of the existence of hydrogen bond-mediated interactions between metal ion-binding sites. 相似文献
6.
7.
8.
Estimation in change-point hazard rate models 总被引:1,自引:0,他引:1
9.
Salt-induced cooperativity in ATPase activity of plasma membrane-enriched fractions from cultured Citrus cells: kinetic evidence 总被引:1,自引:0,他引:1
ATPase activity was studied in plasma membrane-enriched fractions prepared from cultured Citrus sinensis L. cv. Osbeck cells. In general, properties of the plasma membrane ATPase from cultured cells, such as optimal pH and temperature. Vmax and Km were similar to those already observed in higher plants. The effects of high salt concentrations on ATPase activity were studied in membrane fractions derived from salt-sensitive and salt-tolerant cells grown in the presence or absence of salt. NaCl did not have an in vivo effect on Vmax and the apparent Km value for ATP. However, high concentrations of NaCl, or KCl, added in vitro, induced cooperativity in the enzyme and reduced the affinity of the enzyme for its substrate. Isoosmolar concentrations of sucrose or choline chloride failed to do so. Our results suggest that the plasma membrane ATPase of Citrus cells has more than one substrate-binding site on the native form of the enzyme which interact in the presence of salt and act independently in its absence. 相似文献
10.
The theory of interaction parameters has thus far been based on the free-energy relationships in the formation of ternary complexes formed between a pair of ligands and a protein molecule. The concept has been formulted in terms of a thermodynamic square comprised of the free protein, the two binary complexes, and the ternary complex. However, an increasing number of proteins have been found to exist as equilibrium mixtures of two macrostates. The equilibrium constants for such two-state transitions vary quite considerably between the various binary and ternary complexes of a given protein. We show here that the interpretations of interaction parameters in such two-state systems, requiring the use of a thermodynamic cube, are much more complex than those based on the classic thermodynamic square commonly employed. We demonstrate the use of enthalpies of interaction and heat capacities of interaction to analyze the source of observed free enerigies of interaction in such systems. Specifically, we find that measured negative interaction parameters may arise simply from the inability of a system to achieve all of the positive component effects anticipated by the conventional formulation. 相似文献