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1.
Anna von Bonsdorff-Nikander Jukka Rantanen Leena Christiansen Jouko Yliruusi 《AAPS PharmSciTech》2003,4(3):116-123
The aim of this work was to survey how processing parameters affect the crystal growth of β-sitosterol in suspension. The
process variables studied were the cooling temperature, stirring time and stirring rate during recrystallization. In addition,
we investigated the effect a commonly used surfactant, polysorbate 80, has on crystal size distribution and the polymorphic
form. This study describes the optimization of the crystallization process, with the object of preparing crystals as small
as possible. Particle size distribution and habit were analyzed using optical microscopy, and the crystal structure was analyzed
using X-ray diffractometry. The cooling temperature had a remarkable influence on the crystal size. Crystals with a median
crystal length of ≈23 μm were achieved with a low cooling temperature (<10°C); however, a fairly large number of crystals
over 50 μm appeared. Higher cooling temperatures (>30°C) caused notable crystal growth both in length and width. Rapid (250
rpm), continuous stirring until the suspensions had cooled to room temperature created small, less than 50 μm long (median
<20 μm), needle-shaped crystals. The addition of surfactant slightly reduced the size of the initially large crystals. Both
hemihydrate and monohydrate crystal forms occurred throughout, regardless of the processing parameters. By using an optimized
process, it was possible to obtain a microcrystalline suspension, with a smooth texture. 相似文献
2.
Kozina V Geist D Kubinová L Bilić E Karnthaler HP Waitz T Janáček J Chernyavskiy O Krhen I Ježek D 《Histochemistry and cell biology》2011,135(2):215-228
Within the human testis, Reinke’s crystals are found in Leydig cells but their nature and function are poorly understood.
The aim of our study was to investigate the properties of Reinke’s crystals in man with the normal morphology of the testis
(control group) and infertile patients diagnosed with cryptorchidism. 20 biopsies from infertile patients and six biopsies
from men with regular spermatogenesis (20–30 years.) were used. Sections of the testis tissue were stained with haematoxylin
and eosin and a modified Masson’s method. Specimens were observed by bright field, confocal and transmission electron microscopy
(TEM). The number of Reinke’s crystals in investigated groups was determined applying stereological methods. In both groups,
Reinke’s crystals were noted within the cytoplasm and nuclei of Leydig cells. Some “free” crystals were found within the interstitial
space, outside Leydig cells. Confocal microscopy proved to be very useful in the assessment of the shape and 3D reconstruction
of the crystal. TEM analysis confirmed a hexagonal form of the crystal, while crystallographic data on sections of 70–300 nm
thickness provided a better insight into the organization of the crystal lattice. Stereological analysis revealed a significant
increase in the number of crystals in cryptorchid testes when compared with controls. Increased number of crystals in cryptorchid
specimens leads to the assumption that the prolonged exposure to higher (abdominal) temperature might stimulate enzymes involved
in the synthesis of the proteins of the crystal. However, the exact molecular nature of the crystal lattice remains in both
normal and cryptorchid testis obscure. 相似文献
3.
Bisphenoidal shape of α-N,N′-diacetylchitobiose (α-(GlcNAc)2) monohydrate crystals was obtained from aqueous solution. Crystal morphology was studied by computer simulation. Theoretical morphologies calculated by classic models (a BFDH model, a surface free-energy method, and an AE model) deviated significantly from that from the experimental crystal habit. Therefore, a solvent effect was considered by introducing an interface layer model based on molecular dynamics simulation in order to bridge this gap. The results of the simulation showed that the calculated habit is much closer to the experiment, meaning that the interface layer model describes the solvent effect very well. This model may also be applied for other oligosaccharide systems to study the relationship among crystal morphology, crystal structure, and solvation effects. 相似文献
4.
Naimov S Martens-Uzunova E Weemen-Hendriks M Dukiandjiev S Minkov I de Maagd RA 《Molecular biotechnology》2006,32(3):185-196
Many Bacillus thuringiensis crystal proteins, particularly those active against lepidopteran insects, have carboxy-terminal extensions that mediate bipyramidal
crystal formation. These crystals are only soluble at high (>10.0) pH in reducing conditions such as generally found in the
lepidopteran midgut. Most of the Colorado potato beetle (CPB)-active toxins lack such an extension, yet some toxins with a
carboxy-terminal extension have cryptic activity against this insect, revealed only after in vitro solubilization. Crystal
formation, morphology, protein content, and activity against CPB were compared for two sets of proteins, the Cry 1-hybrid
SN19 and Cry3Aa, both with and without a carboxy-terminal extension. Cry3Aa, with or without extension, formed flat square
or rectagular crystals. SN19 (with extension) and its derivative without extension formed irregular inclusion bodies. All
Cry3Aa and SN19 crystals and inclusion bodies were almost equally active before and after in vitro presolubilization and could
be solubilized in diluted CPB midgut extract. In contrast, bipyramidal crystals of Cry1Ba were insoluble under these conditions.
Our results suggest that bipyramidal crystal formation typical for proteins with a carboxy-terminal extension may preclude
activity against CPB, but that interfering with this crystal formation can increase the activity. 相似文献
5.
The purpose of this study was to test the utility of rapid expansion of supercritical solution (RESS) based cocrystallizations
in inducing polymorph conversion and crystal disruption of chlorpropamide (CPD). CPD crystals were recrystallized by the RESS
process utilizing supercritical carbon dioxide as the solvent. The supercritical region investigated for solute extraction
ranged from 45 to 100°C and 2000 to 8000 psi. While pure solute recrystallization formed stage I of these studies, stage II
involved recrystallization of CPD in the presence of urea (model impurity). The composition, morphology, and crystallinity
of the particles thus produced were characterized utilizing techniques such as microscopy, thermal analysis, x-ray powder
diffractometry, and high-performance liquid chromatography. Also, comparative evaluation between RESS and evaporative crystallization
from liquid solvents was performed. RESS recrystallizations of commercially available CPD (form A) resulted in polymorph conversion
to metastable forms C and V, depending on the temperature and pressure of the recrystallizing solvent. Cocrystallization studies
revealed the formation of eutectic mixtures and solid solutions of CPD+urea. Formation of the solid solutions resulted in
the crystal disruption of CPD and subsequent amorphous conversion at urea levels higher than 40% wt/wt. Consistent with these
results were the reductions in melting point (up to 9°C) and in the ΔHfvalues of CPD (up to 50%). Scanning electron microscopy revealed a particle size reduction of up to an order of magnitude
upon RESS processing. Unlike RESS, recrystallizations from liquid organic solvents lacked the ability to affect polymorphic
conversions. Also, the incorporation of urea into the lattice of CPD was found to be inadequate. In providing the ability
to control both the particle and crystal morphologies of active pharmaceutical ingredients, RESS proved potentially advantageous
to crystal engineering. Rapid crystallization kinetics were found vital in making RESS-based doping superior to conventional
solvent-based cocrystallizations. 相似文献
6.
Macromolecular solvation energies derived from small molecule crystal morphology. 总被引:1,自引:1,他引:0
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The morphology of small molecule crystals provides a model for evaluating surface solvation energies in a system with similar packing density to that observed for amino acid residues in proteins. The solvation energies associated with the transfer of methylene and carboxyl groups between vacuum and aqueous phases are estimated to be approx. $40 and -260 cal/A2, respectively, from an analysis of the morphology of succinic acid crystals. These solvation energies predict values for contact angles in reasonable agreement with measurements determined from macroscopic monolayer surfaces. Transfer free energies between vapor and water phases for a series of carboxylic acids are also predicted reasonably well by these solvation energies, provided the surface exposure of different groups is quantitated with the molecular surface area rather than the more traditional accessible surface area. In general, molecular surfaces and molecular surface areas are seen to have important advantages for characterizing the structure and energetics of macromolecular surfaces. Crystal faces of succinic acid with the lowest surface energies in aqueous solution are characteristically smooth. Increasing surface roughness and apolarity are associated with higher surface energies, which suggests an approach for modifying the surface properties of proteins and other macromolecules. 相似文献
7.
Abstract This paper considers the surface structural properties and crystal morphology of crystalline s-triazine. A key feature of the computational approach adopted is the consideration of surface structural relaxation of the uppermost section of the crystal and the use of non-rigid molecules. Crystal morphologies calculated on the basis of surface energies and attachment energies are considered. 相似文献
8.
Piloderma species are broad-host-range fungi associated with a wide variety of conifer and hardwood species to form ectomycorrhizae
(ECM). In this study, we investigated the hypha crystals collected from Piloderma– Picea glauca× engelmannii ECM as an initial step in the elucidation of the role of mycorrhizal fungi in mineral weathering and nutrient cycling. We
compared the morphology and composition of hypha encrustation between field and cultured Piloderma samples. For field samples, the morphology of encrustations was dominated by elongated crystals often underlain by verrucose
crystals. Cultured samples had mostly verrucose crystals. Generally, encrustations on field samples had higher calcium contents
than cultured samples. Calcium contents ranged from 3% in the verrucose crystals of cultured samples to 17% in verrucose and
elongated crystals of field samples. Encrustations had infrared absorption bands at 1333 and 781 cm–1 wavenumbers, indicative of the presence of oxalate. High amounts of C and O in verrucose crystals are likely associated with
the crystal sheath around all encrustations. This composition suggests an intracellular origin for the crystals. It is possible
that encrustations start as verrucose crystals and develop into euhedral elongated crystals susceptible to dislod- gement
into the soil environment. These crystals may prevent the desiccation of the hyphae and inhibit the build-up of calcium and
oxalate in fungus cells.
Accepted: 15 October 2000 相似文献
9.
Marat A. Ziganshin Irina G. Efimova Valery V. Gorbatchuk Sufia A. Ziganshina Anton P. Chuklanov Anastas A. Bukharaev Dmitry V. Soldatov 《Journal of peptide science》2012,18(4):209-214
The ability of highly ordered tripeptide structures to keep or change their morphology in contact with organic vapors was studied. A thin film of tripeptide l ‐leucyl‐l ‐leucyl‐l ‐leucine (LLL) was prepared having microcrystals and nanocrystals on its surface, which are stable upon vacuum drying but become objects of selective morphology change after a contact with vapors of organic solvents. Fine separate LLL crystals and their agglomerates of submicron and larger dimensions were observed by atomic force microscopy and scanning electron microscopy. After saturation with guest vapors, these crystals can remain intact or change their morphology with the increase in size or complete destruction depending on the guest molecular structure. The crystals completely lose their shape after the binding of pyridine vapors. The other studied guests produce much smaller transformations or have no effect on crystal morphology despite being sorbed by solid LLL, which was shown using quartz crystal microbalance sensor. The observed size‐exclusion effect for guest sorption by LLL was found to be broken by the same guests that can change the initial crystal shape. This helps to explain the morphology changes of LLL crystals after the guest sorption and release. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
10.
Zhongqiao Hu 《Molecular simulation》2013,39(2):112-118
A molecular dynamics simulation study is reported for three polymorphic protein crystals (4PTI, 5PTI and 6PTI) of bovine pancreatic trypsin inhibitor (BPTI). The simulated lattice constants are in good agreement with experimental data, indicating the reliability of force field used. The fluctuation patterns of peptide chains in the three crystals are similar, and the protein structures are fairly well maintained during simulation. We observe that water forms a pronounced hydration layer near the protein surface. The diffusion coefficients of water in the three crystals are smaller than in bulk phase, and thus, the activation energies are higher. The porosity, fluctuation of peptide chains and solvent-accessible surface area as well as the diffusion coefficients of water and counterion in 5PTI are the largest among the three crystals. The diffusion of water and counterion is anisotropic, and the degree of anisotropy increases in the order of 4PTI < 5PTI < 6PTI. Despite a slight difference, the structural and diffusion properties in the three BPTI crystals are generally close. This simulation study reveals that crystal polymorphism does not significantly affect microscopic properties in the BPTI crystals with different morphologies. 相似文献
11.
Malek K 《Biotechnology letters》2007,29(12):1865-1873
Long-time equilibrium molecular dynamics simulations were performed to study the passage of a substrate, l-arabinose, through nanopores of orthorhombic hen egg white lysozyme crystals. Cross-linked protein crystals (CLPC), as novel
biological nanoporous media, consist of an extensive regular matrix of chiral solvent-filled nanopores via which ions and
solutes, e.g. sugars and amino acids, travel in and out. We studied the diffusive motion of arabinose inside protein channels.
The computed diffusion coefficients within the crystal were orders of magnitudes lower relative to the diffusion coefficient
of the solute in water. This study is valuable for understanding the nature of solute–protein interactions and transport phenomena
in CLPCs and provides an understanding of biocatalytic and bioseparation processes using CLPC. 相似文献
12.
The aims of this study were to characterize the morphology and size of flocculates and the zeta potential and rheological
properties of polymer–magnesium aluminum silicate (MAS) composite dispersions and to investigate the physical properties of
acetaminophen (ACT) suspensions prepared using the composite dispersions as a flocculating/suspending agent. The polymers
used were sodium alginate (SA), sodium carboxymethylcellulose (SCMC), and methylcellulose (MC). The results showed that SA,
SCMC, and MC could induce flocculation of MAS by a polymer-bridging mechanism, leading to the changes in the zeta potential
of MAS and the flow properties of the polymer dispersions. The microscopic morphology and size of the flocculates was dependent
on the molecular structure of the polymer, especially ether groups on the polymer side chain. The residual MAS from the flocculation
could create a three-dimensional structure in the SA–MAS and SCMC–MAS dispersions, which brought about not only an enhancement
of viscosity and thixotropic properties but also an improvement in the ACT flocculating efficiency of polymers. The use of
polymer–MAS dispersions provided a higher degree of flocculation and a lower redispersibility value of ACT suspensions compared
with the pure polymer dispersions. This led to a low tendency for caking of the suspensions. The SCMC–MAS dispersions provided
the highest ACT flocculating efficiency, whereas the lowest ACT flocculating efficiency was found in the MC–MAS dispersions.
Moreover, the added MAS did not affect ACT dissolution from the suspensions in an acidic medium. These findings suggest that
the polymer–MAS dispersions show good potential for use as a flocculating/suspending agent for improving the rheological properties
and physical stability of the suspensions. 相似文献
13.
为了探讨荒漠植物适应干旱环境的机理, 选择光合器官发生很大变化的5种C4荒漠植物进行了解剖结构的对比研究。结果表明, 这5种 植物中含晶细胞的数量、大小、形态和分布位置等存在差异。白梭梭(Haloxylon persicum)和梭梭(H. ammodendron)的同化枝普遍具有含晶细 胞; 沙拐枣(Calligonum mongolicum)的含晶细胞很少, 一般只分布在贮水组织或靠近栅栏组织处; 木本猪毛菜(Salsola arbuscula)的含晶细 胞也不多, 主要分布在栅栏组织和表皮细胞之间; 猪毛菜(S. collina)的含晶细胞更少, 仅在贮水组织中偶尔可见晶簇。比较梭梭、白梭梭和 沙拐枣同化枝不同部位的解剖结构发现, 梭梭同化枝基部含晶细胞最多, 中部次之, 顶部最少; 白梭梭同化枝顶部的含晶细胞数量较多, 中部 及基部较少; 沙拐枣同化枝顶部与基部的粘液细胞较多, 中部较少, 基部几乎没有栅栏组织, 而其维管组织较为发达。综合晶体的酸碱溶解性 及硝酸银组化分析结果, 并参照能谱仪的分析结果得知, 梭梭、白梭梭、沙拐枣和木本猪毛菜的叶片或同化枝中所含晶体的主要成分为草酸钙 。通过比较解剖结构发现, 梭梭和白梭梭的同化枝中含晶细胞最多, 其它3种植物的同化器官中含晶细胞较少, 而沙拐枣同化枝中有粘液细胞存 在。 相似文献
14.
Surface interactions of gamma-crystallins in the crystal medium in relation to their association in the eye lens 总被引:3,自引:0,他引:3
Y V Sergeev Y N Chirgadze S E Mylvaganam H Driessen C Slingsby T L Blundell 《Proteins》1988,4(2):137-147
A comparative study of intermolecular interactions in crystals of two homologous low molecular weight proteins, gamma-II and gamma-IIIb crystallins, from calf eye lens was carried out. Crystal packings for these proteins are very different: intermolecular contact areas compose about 33% of the total accessible surface area of gamma-II as compared with 13% in gamma-III. Two key residues seem to be mainly responsible for the differences in protein association in the crystal medium. These are Ser 103 and Leu 155 in gamma-II, which are replaced by Met 103 and His 155 in gamma-IIb. A similar substitution of these residues is observed in different gene products of gamma-crystallins from a number of vertebrates. This is consistent with the existence of a genetically controlled mechanism for determining intermolecular association of gamma-crystallins in the native medium of the lens. 相似文献
15.
Bill Pedrini Ching-Ju Tsai Guido Capitani Celestino Padeste Mark S. Hunter Nadia A. Zatsepin Anton Barty W. Henry Benner Sébastien Boutet Geoffrey K. Feld Stefan P. Hau-Riege Richard A. Kirian Christopher Kupitz Marc Messerschmitt John I. Ogren Tommaso Pardini Brent Segelke Garth J. Williams John C. H. Spence Rafael Abela Matthew Coleman James E. Evans Gebhard F. X. Schertler Matthias Frank Xiao-Dan Li 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1647)
Membrane proteins arranged as two-dimensional crystals in the lipid environment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. Previously, X-ray diffraction from individual two-dimensional crystals did not represent a suitable investigational tool because of radiation damage. The recent availability of ultrashort pulses from X-ray free-electron lasers (XFELs) has now provided a means to outrun the damage. Here, we report on measurements performed at the Linac Coherent Light Source XFEL on bacteriorhodopsin two-dimensional crystals mounted on a solid support and kept at room temperature. By merging data from about a dozen single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 Å, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase in the resolution. The presented results pave the way for further XFEL studies on two-dimensional crystals, which may include pump–probe experiments at subpicosecond time resolution. 相似文献
16.
Regulation of seed yield and agronomic characters by photoperiod sensitivity and growth habit genes in soybean 总被引:2,自引:0,他引:2
Elroy R. Cober Malcolm J. Morrison 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(5):1005-1012
Soybean genotypes are adapted to narrow bands of latitude due to photoperiod sensitivity. There are several photoperiod-sensitive
loci (E1, E2, E3, E4, E5, E6, E7, E8). Determinate and indeterminate growth habits are controlled by a single locus. The objective
of our research was to examine the effects of photoperiod sensitivity and growth habit alleles on seed yield and other agronomic
characters using isogenic lines. Twenty ‘Harosoy’ isolines with 11 photoperiod-sensitive genotypes many with both indeterminate
and determinate growth habits were grown in the field at Ottawa, ON, from 2003 to 2007. Maturity ranged from 97 to 127 days,
and seed yield increased linearly with maturity until about 112 days when it plateaued. Determinate lines were always shorter
than indeterminate lines of equivalent maturity. Seed yield was associated with plant height, maturity, seed sugar concentration,
seed weight and lodging. Effects of alleles at individual loci, and additive and epistatic effects across multiple loci were
examined. At a single locus, photoperiod-insensitive alleles produced isolines that matured 8–11 days earlier, yielded less,
and had shorter plants with reduced lodging. In multiple loci analyses, additive effects explained most of the variation in
agronomic characters since additive models with E1, E3, E4, E7 and Dt1 loci included compared well to additive plus epistatic
models and genotype-based models. Variation in photoperiod sensitivity and growth habit alleles results in a range of maturity,
with pleiotropic effects on seed yield and agronomic characteristics, and play an important role in providing adaptation across
latitudes. 相似文献
17.
By using Bio-Beads as a detergent-removing agent, it has been possible to produce detergent-depleted two-dimensional crystals of purified Ca-ATPase. The crystallinity and morphology of these different crystals were analyzed by electron microscopy under different experimental conditions. A lipid-to-protein ratio below 0.4 w/w was required for crystal formation. The rate of detergent removal critically affected crystal morphology, and large multilamellar crystalline sheets or wide unilamellar tubes were generated upon slow or fast detergent removal, respectively. Electron crystallographic analysis indicated unit cell parameters of a = 159 A, b = 54 A, and gamma = 90 degrees for both types of crystals, and projection maps at 15-A resolution were consistent with Ca-ATPase molecules alternately facing the two sides of the membrane. Crystal formation was also affected by the protein conformation. Indeed, tubular and multilamellar crystals both required the presence of Ca2+; the presence of ADP gave rise to another type of packing within the unit cell (a = 86 A, b = 77 A, and gamma = 90 degrees), while maintaining a bipolar orientation of the molecules within the bilayer. All of the results are discussed in terms of nucleation and crystal growth, and a model of crystallogenesis is proposed that may be generally true for asymmetrical proteins with a large hydrophilic cytoplasmic domain. 相似文献
18.
The effect of temperature and solution pH on the nucleation of tetragonal lysozyme crystals.
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Part of the challenge of macromolecular crystal growth for structure determination is obtaining crystals with a volume suitable for x-ray analysis. In this respect an understanding of the effect of solution conditions on macromolecule nucleation rates is advantageous. This study investigated the effects of supersaturation, temperature, and pH on the nucleation rate of tetragonal lysozyme crystals. Batch crystallization plates were prepared at given solution concentrations and incubated at set temperatures over 1 week. The number of crystals per well with their size and axial ratios were recorded and correlated with solution conditions. Crystal numbers were found to increase with increasing supersaturation and temperature. The most significant variable, however, was pH; crystal numbers changed by two orders of magnitude over the pH range 4.0-5.2. Crystal size also varied with solution conditions, with the largest crystals obtained at pH 5.2. Having optimized the crystallization conditions, we prepared a batch of crystals under the same initial conditions, and 50 of these crystals were analyzed by x-ray diffraction techniques. The results indicate that even under the same crystallization conditions, a marked variation in crystal properties exists. 相似文献
19.
ABSTRACTMulti-level theory simulations have been performed to model a number of important molecular properties of a bent-core nematic liquid crystal (LC) A131. These important properties include molecular conformations, molecular Raman spectra, differential polarisability ratios, molecular crystals packing, atomic LC structures, order parameters, and Raman depolarisation spectra. The simulations contain four theory levels, involving molecular quantum chemistry, molecular crystal packing, super cell density functional based tight binding optimisation, and super cell molecular dynamics calculations. To heat initial optimised super cell structures, molecular dynamics simulations reveal phase transitions to uniaxial and biaxial nematic phases from molecular crystals. LC atomic structures result in direct calculations on order parameters, which can be further applied to computations on Raman depolarisation spectra with differential polarisability ratios, obtained in the molecular quantum chemistry theory level. The good agreement of simulated Raman depolarisation spectra with the experiment provides a detailed analysis on the unusually low values of experimental uniaxial order parameters. 相似文献
20.
Rolf Borchert 《Planta》1990,182(3):339-347
Changes in the spacing patterns of Ca-oxalate crystals during enlargement ofCarya ovata Mill. leaves were quantified by computerized image-analysis. Single Ca-oxalate crystals form in the vacuoles of young mesophyll
cells transformed into crystal cells Crystals are very small in newly induced crystal cells and increase in size throughout
leaf development. Crystal patterns thus reflect both induction and relative age of crystal cells. Shortly after the emergence
of young leaves from the bud, very small crystals are formed in the mesophyll at high density. As leaves expand, these crystals
grow larger and become separated by increasing distances. New small crystals appear in the gaps between the older, larger
crystals. Later crystal patterns consist of widely spaced, larger crystals only. Finally, clusters of small crystals are formed
again in the gaps between large crystals. No crystals were observed in young leaves expanding in a moist chamber, but large
numbers of crystal cells were induced experimentally in sections of immature leaves floating on 4 mM Ca-acetate. The observations
support the following mechanism of crystal-pattern formation: Ca2+ carried into leaves with the transpiration stream acts as the developmental signal inducing transdifferentiation of a few
mesophyll cells into crystal cells when apoplastic [Ca2+] rises. Crystal cells precipitate absorbed Ca2+ as oxalate and, acting as Ca2+ sinks, inhibit crystal-cell induction in their vicinity by depleting apoplastic Ca2+. This prevents close spacing of crystal cells. New crystal cells form in the gaps between the depletion zones of older crystal
cells when these move apart during leaf expansion. Later changes in crystal patterns result from increasing sink strength
of crystal cells, lowered inducibility of mesophyll cells, and increased Ca2+ influx into leaves during intensive transpiration. Throughout leaf development, spacing of crystal cells permits rapid secretion
of apoplastic Ca2+ as Ca-oxalate.
Dedicated to Professor Erwin Bünning, University of Tübingen, Germany, who pioneered the analysis of spacing patterns 相似文献