Achiral Calcium‐Oxalate Crystals with Chiral Morphology from the Leaves of Some Solanacea Plants

Abstract

Dedicated to Professor Duilio Arigoni on the occasion of his 75th birthdayThe leaves of some plants, particularly among the Solanacea, contain crystals of calcium oxalate with a peculiar chiral pseudo-tetrahedral morphology, even though the calcium oxalate crystal structure is centrosymmetric, hence achiral. We studied the morphology of these crystals extracted from the leaves of three Solanacea plants: the potato, the hot pepper, and a species of wild Solanum. The crystal morphology was the same in all three species. Based on the examination of more than 100 crystals from each plant, we showed that the crystal morphology is chiral with invariant chirality. We suggest that morphological chirality is induced by macromolecules during nucleation from a specific, genetically encoded crystal plane, and is further established during subsequent controlled crystal growth. This is one of few examples where it is possible to deduce a molecular mechanism for biologically induced breaking of morphological symmetry in organisms. A very high level of recognition is required by the macromolecules to allow them to distinguish between symmetry-related crystal planes. It is also surprising that this finely controlled mechanism of crystal formation, including the chiral morphology, has been conserved during evolution.Introduction. ± Morphological mirror symmetry is commonly observed in nature. When the morphological symmetry is broken, however, the resulting object may exist in two mirror-related, or enantiomorphous, forms. In the latter case, it is often only one particular mirror image that is induced in biology, and not the other. The term breaking of morphological symmetry refers here to permanently and invariantly removing from the morphology of a symmetrical object symmetry elements of the second kind such as mirror planes or centers of inversion [1]. The resulting object has a chiral morphology in the classical sense, i.e., it is not super-imposable on its mirror image [2] [3].Snails are a common and classical example of morphological chirality, having spiral shells that revolve in a clockwise direction for more than 98% of the individuals of a given species [4]. Chirality is, thus, characteristic not only of the particular individual, but of the entire population. Because only one of the mirror-related morphologies exists, we refer to it as invariant chirality. It transpires that the direction of revolution of snail shells is determined genetically, and manifests itself as soon as at the stage of the second cellular division [5]. How this is determined is, however, not yet understood.Other well-known examples of spiral morphology are found in the direction of juxtaposition of the leaves of some plants, or the direction of twining of various climbing plants. Notably, approximately 30% of these twine constantly in one direction [4]. This phenomenon, noted and discussed by Darwin [6], may have originated from environmental stimuli, such as the direction of the sunlight, but was later transformed into a genetically encoded char...

Processes Modulating Calcium Distribution in Citrus Leaves. An Investigation Using X-Ray Microanalysis with Strontium as a Tracer

“…We found no indication of particulate calcium in these cells that would indicate the presence of calcium oxalate. Even when present as crystal sand, the calcium oxalate particles can be up to 5 mm in length (Levy-Lior et al, 2003), well within the resolution of mapping. The absence of detectable crystals in the mesophyll cells contrasts with the obvious inclusions in crystal idioblasts (Figs.…”

Biogenic synthesis of calcium oxalate crystal by reaction of calcium ions with spinach lixivium

“…Fig. 2c shows the UV-vis spectra (in the wavelength of 360-580 nm) of the mixture solution containing Bcp-H 2 O 2 and the spinach root lixivium taken out at the time of 2, 4, 6, 8, 10, 12, 14,16,18,20,22,24,26,28,30,32 and 36 h. It could be found that the intensity of the strong peak centered at 435 ± 1.0 nm clearly increased with the reaction time increasing, indicating that the content of oxalate acid in the root lixivium increase as the immersion time increasing. The results reveal that oxalate acid can be liberated from spinach root to aqueous solution and the total released mass depends on the immersion time.…”

“…The concentration of C 2 O 4 2− ions of the root spinach lixivium was determined by using 1.00 mL lixivium to replace the above C 2 O 4 2− working solution. The root lixivium was prepared by putting 100 ± 0.5 g cleaned spinach into 100 mL double distilled water, and the lixiviums were respectively taken out at the times of 2, 4, 6, 8, 10, 12, 14,16,18,20,22,24,26,28,30,32 and 36 h. The above experiments were done two times, the obtained data showed well reproducibility.…”

“…Ward and co-workers [16,17] have reported that PolyD, and PolyE with substantial anionic functionality (e.g., carboxylate) played an important role in selectivity toward COM and COD, and found that the carboxylate-rich proteins might serve as adhesives and could promote the aggregation of COM crystals. Addadi and co-workers [18,19] have investigated CaOx crystal presented in the leaves of plants, such as the potato, the tomato, the tobacco, the hot pepper, and even a specie of wild Solanum, and found that the crystal-associated macromolecules extracted from the planes played a very high level of recognition to distinguish the symmetry-related crystal planes, and influenced the morphology of CaOx crystal during evolution. In our previous studies, we have constructed reverse and bicontinuous microemulsions with solubilizing the tryptophan, tyrosine and aspartic acid to imitate the environment of biological cell and mimetic the process of CaOx crystal nucleation and growth, and found that the amino acids, and surfactants could promote the formation of COM crystal [12].…”

Single Amino Acids as Additives Modulating CaCO3 Mineralization

“…Not only it is found in many microorganisms as a structural component, but it can furthermore be used for navigation along the Earth's magnetic field. In all these diverse examples of biomineralization processes, a common theme can be found in each case-mineralization occurs in the presence of an organic matrix that appears to direct mineral and ultrastructural morphology (4-6) (7) (8) (9)(10)(11) (12). A closer look at the mineralized tissues of certain invertebrates shows that CaCO 3 is the predominant mineral composition utilized, but have completely different structural features from its geological counterparts.…”