Druse Crystals Research Articles

The Role of Druse and Raphide Calcium Oxalate Crystals in Tissue Calcium Regulation in Pistia stratiotes Leaves

Abstract: Ca oxalate crystal formation was examined in Pistia stratiotes L. leaves during excess Ca and Ca‐deficient conditions. Pistia produces druse crystal idioblasts in the adaxial mesophyll and raphide idioblasts in the abaxial aerenchyma. Raphide crystals were previously found to grow bidirectionally, and here we show that Ca is incorporated along the entire surfaces of developing druse crystals, which are coated with membrane‐bound microprojections. Leaves formed on plants grown on 0 Ca medium have fewer and smaller druse crystals than leaves formed under 5 mM Ca (“control”) conditions, while raphide crystal formation is completely inhibited. When plants were moved from 0 to 15 mM (“high”) Ca, the size and number of crystals in new leaves returned to (druse) or exceeded (raphide) control levels. High Ca also induced formation of druse, but not raphide, crystals in differentiating chlorenchyma cells. When plants were transferred from 15 mM Ca to 0 Ca, young druse crystals were preferentially partially dissolved. Oxalate oxidase, an enzyme that degrades oxalate, increased during Ca deficiency and was localized to the crystal surfaces. The more dynamic nature of druse crystals is not due to hydration form as both crystal types are shown to be monohydrate. Part of the difference may be because raphide idioblasts have developmental constraints that interfere with a more flexible response to changing Ca. These studies demonstrate that excess Ca can be stored as Ca oxalate, the Ca can be remobilized under certain conditions, and different forms of Ca oxalate have different roles in bulk Ca regulation.

Reserves of aluminium and mineral nutrients in seeds ofEucalyptus calophylla(Myrtaceae) with reference to the globoid inclusions

AbstractAmounts of mineral nutrients and aluminium (Al) were assessed in the globoid inclusions, proteinaceous matrix and druse crystals ofEucalyptus calophyllaseeds collected from trees grown in coal-mine (mean soil pH 4.3, Al 260 μg g−1) and forest soils (pH 5.3, Al 10 μg g−1). Energy-dispersive X-ray microanalysis (EDX) of bulk frozen hydrated samples indicated that significantly higher amounts of Mg, P, S, K and Ca occurred in the globoid inclusions of mine- than forest-site seeds. In both seedstocks, Al was detected in the globoid inclusions but not in the proteinaceous matrix or druse crystals. Significantly higher amounts of Al occurred in mine-site samples of dry and germinating seeds than in forest-site seeds. It was concluded that globoid inclusions may be useful as indicators of the soil conditions in which the parent plant was grown.

Fruit structure of the southern African species of Apodytes E. Meyer ex Arn. (Icacinaceae)

Fruit development and structure of three southern African species of Apodytes were examined by light and scanning electron microscopy. These are A. dimidiata E. Meyer ex Arn. subsp. dimidiata and two undescribed species designated Apodytes sp. nov. A and B. Fruits are unilaterally developed drupes, ellipsoid and somewhat compressed laterally, with a large succulent appendage. Appendages of A. dimidiata and Apodytes sp. nov. A are predominantly red, whereas those of Apodytes sp. nov. B are a pale translucent green. In all three species the appendages turn black in old fruit. The exocarp is uniseriate and develops solely from the outer epidermis of the ovary wall. The mesocarp is partly parenchymatous, with vascular bundles and cells containing druse crystals of calcium oxalate, and partly lignified ( = stone). The uniseriate endocarp s. str. develops from the inner epidermis of the ovary wall. In a sense the fruit of Apodytes is a composite of parts comparable to a nut (alternatively an achene) and a fleshy drupe. The drupaceous part (fleshy appendage) is a derived structure which develops from the sterile carpel of a reduced locule. We suggest that the fleshy appendage originates as an indicator of seed/fruit maturity, and to attract avian disperser. Limited field observations support the idea that the red/black appendages of A. dimidiata and Apodytes sp. nov. A also serve as an edible reward for birds. Dispersal of fruit of Apodytes sp. nov. B, with its rather inconspicuously coloured appendage, may be dependent on a specialized fruit/frugivore relationship.

Fruit structure of the southern African species of Apodytes E. Meyer ex Arn. (Icacinaceae)

Abstract Fruit development and structure of three southern African species of Apodytes were examined by light and scanning electron microscopy. These are A. dimidiata E. Meyer ex Arn. subsp. dimidiata and two undescribed species designated Apodytes sp. nov. A and B. Fruits are unilaterally developed drupes, ellipsoid and somewhat compressed laterally, with a large succulent appendage. Appendages of A. dimidiata and Apodytes sp. nov. A are predominantly red, whereas those of Apodytes sp. nov. B are a pale translucent green. In all three species the appendages turn black in old fruit. The exocarp is uniseriate and develops solely from the outer epidermis of the ovary wall. The mesocarp is partly parenchymatous, with vascular bundles and cells containing druse crystals of calcium oxalate, and partly lignified ( = stone). The uniseriate endocarp s. str. develops from the inner epidermis of the ovary wall. In a sense the fruit of Apodytes is a composite of parts comparable to a nut (alternatively an achene) and a fleshy drupe. The drupaceous part (fleshy appendage) is a derived structure which develops from the sterile carpel of a reduced locule. We suggest that the fleshy appendage originates as an indicator of seed/fruit maturity, and to attract avian disperser. Limited field observations support the idea that the red/black appendages of A. dimidiata and Apodytes sp. nov. A also serve as an edible reward for birds. Dispersal of fruit of Apodytes sp. nov. B , with its rather inconspicuously coloured appendage, may be dependent on a specialized fruit/frugivore relationship.

Fruit structure of the genus Cassinopsis Sond. (Icacinaceae) in Africa

Fruit development and structure of the two African species of Cassinopsis were examined by light microscopy. Both species are characterized by drupes: ovate-oblong, laterally compressed and yellow-orange in C. ilicifolia, oblong and black in C. tinifolia. The exocarp is uniseriate and develops solely from the outer epidermis of the ovary. A parenchymatous mesocarp with vascular bundles and scattered druse crystals of calcium oxalate is derived from the ground tissue of the ovary wall. A uniseriate parenchymatous (C. ilicifolia) (lignified in C. tinifolia) endocarp s. str. develops from the inner epidermis of the ovary wall. A lignified stone is derived mainly from the inner zone of the mesocarp. The outer surface of the stone is of taxonomic significance, being smooth in C. ilicifolia and longitudinally ribbed in C. tinifolia. Differences in fruit structure, combined with other characters, suggest that the two African species are not taxonomically closely related. Their generic status requires further comparative study, particularly with species of Cassinopsis in Madagascar.

Developmentally regulated antigen associated with calcium crystals in tobacco anthers

We have found and characterized an antigen associated with crystal-containing cells in the stomium and connective tissue of the anthers of Nicotiana tabacum L. (tobacco). The antigen, defined by the monoclonal antibody NtF-8B1, localizes to subcellular regions surrounding the crystals. At the light-microscope level, the antigen is detectable just after the first appearance of crystals in the connective tissue of the anther, and at approximately the same time as the appearance of crystals in the stomium. The antigen is not detectable on a Western blot, and gave inconclusive results on a test of periodate sensitivity. It is not the crystals themselves, nor is the presence of the crystals required for antibody recognition. The antigen is sensitive to heat and protease treatment, indicating that it is a protein. The antigen is not tightly membrane-bound, in spite of its localization closely surrounding the crystals. Chemical tests indicate that the druse crystals in the stomium are calcium oxalate.

Wood Anatomy of the Stalactite-Like Branches of Ginkgo

The morphology and anatomy of stalactite· like branches occurring on old trees of Ginkgo biloba are described. The external morphology and structure of the bark are similar to that of normal branches. However, the growth rings are usually narrower than normal ones. The central portion contains many dark-coloured pith-flecks. Among the axial tracheids there are some zones of irregularly oriented tracheids and in some places the tracheids are arranged in whirls with tortuous rays among them. In the tracheids, 2-4-seriate bordered pits occur in the radial walls. Druse crystals are common.

Structure and development of follicles of Nerium indicum Mill. (Apocynaceae)

AbstractFruit of Nerium is an aggregate of two follicles, developing from a bicarpellary sub‐apocarpous pistil with numerous ovules on marginal placenta. Both the carpels are close to each other by their ventral sides from base to tip as a result of a post‐genital carpel fusion. Ovary wall is homogenous parenchymatous differentiated into outer epidermis, mesodermis and inner epidermis. Epicarp developing from the outer epidermis, is single layered in the early stages of development, but later it becomes multilayered towards maturity. Epicarp is highly folded, possessing stomata and hairs on its surface. Mesocarp is parenchymatous embedding, laticifers and vascular bundles with sclerefied bundle caps. Endocarp is multilayered and sclerenchymatous possessing druse crystals. Separation of the two ventrally fused follicles initiates first and afterwards each follicle dehisces marginicidally. Seeds are oval, cylindrical and covered all over the surface with small brown hairs, but long hairs are also present at one end.

Gold speckles and crystals in tomato fruits (Lycopersicon esculentumMill.)

SummaryTomato fruit walls often possess tiny yellowish spots around the calyx and shoulders of the fruit, so-called gold speckles. In some cases these become very numerous and lead to down-grading of the fruit. In such fruit crystal sand is present in separate cells and groups of cells in the outermost parenchymatous tissue layers of the mesocarp. This crystal sand causes the gold speckles. Also raphid crystals occur in great quantities in the pulp of those tomatoes which display numerous gold speckles in the wall. Druse crystals are absent. Both crystal sand and raphid crystals proved to be organic calcium salts, probably calcium oxalate. Silicon was associated with the crystal sand containing cells of the mesocarp, either as very small silica grains in the cell or randomly distributed in the cell wall as in normal cells. The long raphid crystals may perforate neighbouring parenchyma cells during picking and transporting of the fruit and hence limit its storage life-time. Nutrient substances used in substrate culture, especially those with a high nitrate-ion concentration, may be partly responsible for the formation of the calcium oxalate crystals.

DISTRIBUTION OF CALCIUM OXALATE CRYSTAL IDIOBLASTS IN LEAVES OF TARO (COLOCASIA ESCULENTA)

Cleared leaves of taro (Colocasia esculenta) were examined microscopically to determine changes in the distribution of both druse and raphide idioblasts during a late developmental process—leaf unfurling and expansion. Druse crystal idioblasts are small spherical cells found throughout the lamina, mostly in subepidermal areas. Two types of raphide idioblasts were observed in taro leaves: the nondefensive raphide idioblasts, which are elongated cells usually found embedded in tissues of the leaf margins; and the defensive raphide idioblasts, also elongated cells, but usually found suspended between mesophyll cells in leaf airspaces. The densities of both druse and raphide cells were highest at the fully furled stage and least in the mature, unfurled stage, after substantial leaf expansion. During leaf unfurling, the raphide cells showed a bilaterally symmetrical distribution during all stages from fully furled to mature, unfurled leaves. The distribution of druse cells was bilaterally symmetrical during the fully furled and unfurled stages, but, during unfurling, when one half of the lamina is unfurled and the other half is still tightly furled, up to 80% of the druse cells were found on the unfurled half of the lamina.

Distribution of Calcium Oxalate Crystal Idioblasts in Leaves of Taro (Colocasia esculenta)

Cleared leaves of taro (Colocasia esculenta) were examined microscopically to determine changes in the distribution of both druse and raphide idioblasts during a late developmental process—leaf unfurling and expansion. Druse crystal idioblasts are small spherical cells found throughout the lamina, mostly in subepidermal areas. Two types of raphide idioblasts were observed in taro leaves: the nondefensive raphide idioblasts, which are elongated cells usually found embedded in tissues of the leaf margins; and the defensive raphide idioblasts, also elongated cells, but usually found suspended between mesophyll cells in leaf airspaces. The densities of both druse and raphide cells were highest at the fully furled stage and least in the mature, unfurled stage, after substantial leaf expansion. During leaf unfurling, the raphide cells showed a bilaterally symmetrical distribution during all stages from fully furled to mature, unfurled leaves. The distribution of druse cells was bilaterally symmetrical during the fully furled and unfurled stages, but, during unfurling, when one half of the lamina is unfurled and the other half is still tightly furled, up to 80% of the druse cells were found on the unfurled half of the lamina.

Protein body inclusions in seeds of Eucalyptus maculata and Eucalyptus erythrocorys

Polarizing light microscope studies of sections of embryo tissues revealed the presence of birefringent druse crystals in certain protein bodies of Eucalyptus erythrocorys and E. maculata. Light and electron microscope studies show that the location, size, and structure of the protein bodies that contain druse crystals differ in these two species. These species also differ in the number of druse-containing protein bodies occurring per cell and the size and structure of the druse crystals. Energy-dispersive X-ray analysis, acid solubility, and microincineration tests showed that these druse crystals are composed of calcium oxalate. In both species the druse crystals were retained by the seedling during germination and early seedling growth. Seeds of both Eucalyptus species also contain globoid crystals in most, nonprotodermal protein bodies.

The Chemistry and Microstructure of Protein Bodies in Celery Endosperm

Anatomical variations in regions of the endosperm and the structure and composition of protein bodies of ungerminated celery (A pium graveolens) fruits were examined by histochemistry, light microscopy, electron microscopy, and X-ray analysis. Protein bodies contained either phytin globoids with Mg and P and lesser amounts of Ca and K or Ca oxalate druse crystals that had only Ca peaks. Most of the Ca in the fruit is stored in the druse crystals, which are broken down more slowly than the globoids during germination. Cells in the central region of the endosperm, distal to the cotyledons, contained enlarged protein bodies and other cellular features, indicating that they had already undergone some autolysis prior to the onset of germination. Such cells would be expected to appear to respond earlier to the application of exogenous gibberellin than more peripheral cells in the endosperm. The apparent early response of central cells in isolated endosperm halves may therefore not depend on an inherent differen...

Protein bodies in seeds

Membrane bound protein bodies (aleurone grains) are thought to be the main subcellular location of protein and mineral storage in seeds. In addition to structurally homogeneous proteinaceous matrix, protein bodies may contain protein crystalloids, electron–dense globoid crystals, electron–transparent soft globoids, and crystals of calcium oxalate. Protein crystalloids vary in shape, size and number. For example, cotyledon mesophyll cell protein bodies in the Cucurbitaceae generally contain protein crystalloids whereas those of Compositae and Cruciferae do not. Globoid crystals, which are rich in phytin, vary greatly in size and number per protein body. Some species have numerous small globoid crystals per protein body whereas others have one or two large globoid crystals per protein body. Phosphorus and various cations (K, Mg, Ca, Fe, Ba, Mn) located in globoid crystals can be studied with an energy dispersive X–ray (EDX) analysis system mounted on a transmission electron microscope. In some cases, cations such as Ca, Mn and Fe are specifically localized in globoid crystals of certain tissues or embryo regions. Further investigations may allow elemental composition of globoid crystals to be used in studies of systematics. Biref–ringent crystals, sometimes in the form of single large crystals but frequently in the form of druses, are present in protein bodies of some species. At least some endosperm protein bodies of all Umbelliferous species examined contain druse crystals. While seed protein bodies of relatively few species have been studied with electron microscopy, there are indications that protein bodies could be a useful character for studies in plant systematics.

THE ASSOCIATION OF DRUSE CRYSTALS WITH THE DEVELOPING STOMIUM OF CAPSICUM ANNUUM (SOLANACEAE) ANTHERS

Each of the two stomiums in the anther of Capsicum annuum (sweet pepper) consists of a single layer of cells immediately below the epidermis between two adjacent locules. Each stomium extends the entire length of the anther and splits open at pollen maturity. Many calcium oxalate druse crystals form within the vacuoles of the stomium cells in association with membrane complexes and paracrystalline bodies. These latter structures are reported here for the first time and each is considered to be a nucleation site for druse crystal formation. Prior to the appearance of membrane complexes and crystals within the vacuoles, plasmalemmasomes are visible next to the stomium cell walls and contain vesicles and fibrous material. We propose that these bodies carry wall materials, including calcium ions and possibly oxalate ions, into the vacuoles. Their presence coincides with crystal formation. Two other types of crystals occur in the connective tissue between stomiums and the single vascular strand. These crystals, along with those in the two stomiums, form at precise times during anther development. Contrary to the more numerous suggestions that crystals protect against predators or are metabolic waste products, we believe their formation aids in degradation and weakening of the cell walls between the locules and, thus, contributes to the release mechanism for the pollen.

The Association of Druse Crystals with the Developing Stomium of Capsicum annuum (Solanaceae) Anthers

Each of the two stomiums in the anther of Capsicum annuum (sweet pepper) consists of a single layer of cells immediately below the epidermis between two adjacent locules. Each stomium extends the entire length of the anther and splits open at pollen maturity. Many calcium oxalate druse crystals form within the vacuoles of the stomium cells in association with membrane complexes and paracrystalline bodies. These latter structures are reported here for the first time and each is considered to be a nucleation site for druse crystal formation. Prior to the appearance of membrane complexes and crystals within the vacuoles, plasmalemmasomes are visible next to the stomium cell walls and contain vesicles and fibrous material. We propose that these bodies carry wall materials, including calcium ions and possibly oxalate ions, into the vacuoles. Their presence coincides with crystal formation. Two other types of crystals occur in the connective tissue between stomiums and the single vascular strand. These crystals, along with those in the two stomiums, form at precise times during anther development. Contrary to the more numerous suggestions that crystals protect against predators or are metabolic waste products, we believe their formation aids in degradation and weakening of the cell walls between the locules and, thus, contributes to the release mechanism for the pollen.

MORPHOLOGY AND ANATOMY OF RESIN GLANDS IN SALIX LUCIDA (SALICACEAE)

Resin glands on the first leaves to emerge occur at the tip of each marginal dentation of the lamina and stipule, and on the adaxial surface of the stipule and lamina bases (the latter often extend onto the petiole). Successive emerging leaves show increases in number of basilaminar glands, because increasingly elaborate multiglandular stalks develop. Glands in all locations are conical or domed, with a palisade‐like epidermis subtended by 5–6 layers of parenchyma which contains druse crystals. A single vascular bundle (sometimes two or three) ends in a small knob of tracheary elements. Glands usually secrete liquid resin that covers the gland and surrounding area and under certain conditions, particularly in low humidity, resin is extruded as a filament from a pore in the gland apex, a mode of resin secretion not described previously. Glands secreting liquid resin have an apical dimple, but presence of a pore has not been established.

Calcium oxalate druse crystals and other inclusions in seed protein bodies: Eucalyptus and jojoba

Druse crystals of calcium oxalate are known to occur in some protein bodies of some plant seeds. This paper reports observations on crystals, and other contents, of protein bodies of Eucalyptus erythrocorys and Simmondsia chinensis (jojoba). Results are presented from thin section studies of glutaraldehyde–OsO4 fixed, dehydrated, and embedded tissue; freeze-fracture studies; energy dispersive x-ray (EDX) analysis studies of freeze-dried tissue powders (Eucalyptus only); and chemical analysis studies of P, Mg, K, and Ca content (Eucalyptus only). Many Eucalyptus protein bodies contained large druse crystals rich in Ca but devoid of P, K, and Mg, and an occasional protein body from jojoba contained some dispersed crystals. Eucalyptus seeds were exceptionally high in Ca content. EDX analysis results provide evidence favouring the phytin-rich nature of globoid crystals in the two species. Structural variation in the globoid crystals was great, especially in jojoba. Eucalyptus, whose protein bodies contained very large globoid crystals rich in P, Mg, and K, was found to have higher levels of these elements than most species investigated to date.

Location of reserves of mineral elements in seed protein bodies: macadamia nut, walnut, and hazel nut

This paper presents the results of thin-section, freeze-fracture, energy dispersive x-ray (EDX) analysis, and chemical analysis studies of cotyledon tissue from dry seeds of macadamia nut (Macadamia integrifolia), walnut (Juglans regia), and hazel nut (Corylus avellana). Studies concentrated on mineral elements in the storage protein bodies. Protein bodies of macadamia nut contained no protein crystalloids but did contain some globoid crystals. Aqueous fixation of macadamia tissue appeared to result in a rapid solubilization of proteinaceous matrix material. EDX analysis of macadamia nut globoid crystals revealed the presence of P, K, and Mg in most cases but the occasional crystal was very high in calcium. Walnut protein bodies often contained many large protein crystalloids. Globoid crystals were present between the protein crystalloids and in the proteinaceous matrix. EDX analysis indicated the presence of P, K, and Mg as the main elements in walnut globoid crystals. Hazel nut protein bodies contained one or more small protein crystalloids, globoid crystals of various sizes, and proteinaceous matrix. Some protein bodies contained druse crystals. EDX analysis showed that the druse crystals were rich in calcium and thus are presumably calcium oxalate. EDX analysis of globoid crystals revealed the presence of elements consistent with the phytin-rich nature of globoid crystals. Variations in globoid crystal composition are discussed.