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F J Stevens F A Westholm N Panagiotopoulos M Schiffer R A Popp A Solomon 《Journal of molecular biology》1981,147(1):185-193
A “naturally occurring” human κI VL dimer, designated Wat, has been isolated and crystallized. Protein Wat consists of two non-covalently bound monomers, each having a molecular weight of ~ 11,500. The monomer subunit is composed of an entire variable region light chain (VL) domain closely homologous to that of the κI Bence Jones protein Roy (Hilschmann &; Craig, 1965) as evidenced from amino acid composition, tryptic peptide map, and sequence analysis. Immunochemical studies substantiated that protein Wat is of the κ chain subgroup κI and lacks the isotypic and allotypic antigenic determinants associated with the κ constant region light chain domain. Two types of crystals of VL dimer Wat were obtained from ammonium sulfate or polyethylene glycol solutions. The type I crystals have unit cell dimensions of , and the space group is hexagonal P62 or P64. The asymmetric unit consists of one VL dimer; the fractional volume of unit cell occupied by solvent is 0.51. The unit cell dimensions of the type II crystals are ; the space group is hexagonal P6122 or P6522. Three variable domains constitute the asymmetric unit of the type II crystals; the fractional value of the solvent (0.52) is compatible with the value obtained for the type I crystals. 相似文献
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For the first time the expression of C3 and CAM in the leaves of different age of Marrubium frivaldszkyanum Boiss, is reported. With increasing leaf age a typical C3 photosynthesis pattern and high transpiration rate were found. In older leaves a shift to CAM occurred and the 24-h transpiration water loss decreased. A correlation was established between leaf area and accumulation of malate. Water loss at early stages of leaf expansion may be connected with the shift to CAM and the water economy of the whole plant. 相似文献
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Schery Umanzor Mary Mar Ramírez-García Jose Miguel Sandoval-Gil José Antonio Zertuche-González Charles Yarish 《Journal of phycology》2020,56(2):380-392
This study was designed to understand better if and how juvenile sporophytes of Macrocystis pyrifera can photoacclimate to high-light conditions when transplanted from 10 to 3 meters over 7 d. Acclimation of adult sporophytes to light regimes in the bathymetric gradient has been extensively documented. It primarily depends on photoacclimation and translocation of resources among blades. Among other physiological differences, juvenile sporophytes of M. pyrifera lack the structural complexity shown by adults. As such, juveniles may primarily depend on their photoacclimation capacities to maintain productivity and even avoid mortality under changing light regimes. However, little is known about how these mechanisms operate in young individuals. The capacity of sporophytes to photoacclimate was assessed by examining changes in their photosynthetic performance, pigment content, and bio-optical properties of the blade. Sporophytes nutritional status and oxidative damage were also determined. Results showed that juvenile sporophytes transplanted to shallow water were able to regulate light harvesting by reducing pigment concentration, and thus, absorptance and photosynthetic efficiency. Also, shallow-water sporophytes notably enhanced the dissipation of light energy as heat (NPQ) as a photoprotective mechanism. Generally, these adjustments allowed sporophytes to manage the absorption and utilization of light energy, hence reducing the potential for photo-oxidative damage. Furthermore, no substantial changes were found in the internal reserves (i.e., soluble carbohydrates and nitrogen) of these sporophytes. To our knowledge, these results are the first to provide robust evidence of photoprotective and photoacclimation strategies in juveniles of M. pyrifera, allowing them to restrict or avoid photodamage during shallow-water cultivation. 相似文献
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A mathematical model was developed for resolved temporal transients of experimentally recorded delayed fluorescence (DF) induction
signal. During an intermittent light regime, antennas of the photosynthetic apparatus were treated as targets, repeatedly
hit by potentially absorbable photons within a series of consecutive light flashes. Formulas were derived for the number of
antennas, cumulatively hit by a specific number of photons, as a function of the flash serial number (time). Model parameters
included number of absorbable photons in one flash, antenna sizes, and their number. A series of induction curves were analyzed,
obtained from a Zea mays leaf segment and differing in the previous dark period (t
d). Each curve, consisting of the two most prominent DF transients (C and D), was fitted with several model types, differing in the number of absorbed photons. For both transients, the best fitting
result was achieved when DF induction was linked to the second absorbed photon. As expected, model parameters related to antenna
sizes showed weaker dependence on t
d than those referring to antenna number. With restrictions applied to this model, the two DF induction transients may be related
to two classes of photosynthetic antennas. Their different sizes may have a predominant influence on the efficiency of photon
absorption and possibly time-dependent appearance of DF transients.
Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 3, pp. 325–335.
The text was submitted by the authors in English. 相似文献
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Notes on compositional diversity 总被引:5,自引:4,他引:1
Pál Juhász-Nagy 《Hydrobiologia》1993,249(1-3):173-182
This paper tries to show some ways and means of simple (binary) modelling, whereby diversity can be interconnected with other attributes of a community. A new type of scaling (called characteristic scaling) is introduced for further use. 相似文献
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Receiver operating characteristic (ROC) curves are used to describe the performance of diagnostic procedures. This paper proposes a simple method for the statistical comparison of two ROC curves derived from the same set of patients and the same set of healthy subjects. Generalization to studies involving more than two screening factors is straightforward. This method does not require the calculation of variances of the areas or difference of areas under the curves. 相似文献