The compounds in Aloë leaf exudates: a review

The drug Bitter Aloes has been used for several thousands of years because of its purgative properties and later several species of the plant have been cultivated for horticultural interest. In addition, many more local therapeutic properties have been recorded. Research has been largely directed towards the physiologically active components during the 50s and 60s. Extensions to this work in the last decade have been made in Germany, Japan and South Africa. Compounds have been characterized from the dried exudate prepared for drug purposes and from a few species. A number of anthraquinones have been recognized both in the free state and as glycosides. Other compounds with phenolic groups include chromones and a phenyl-pyranone. Chromatographic methods have been developed for recognizing some of these compounds and estimating the levels of those of pharmacological interest. Distribution of some of the compounds among a number of species is described showing that among some groups it has taxonomic significance. The biology of secretion and exudation from Aloë leaves remains largely unknown although fragmentary evidence points to interesting and potentially useful activity in some of the components.     

植物晶体的形态结构、生物功能及形成机制研究进展

晶体是植物体内产生的一种具有特殊形态结构与生理功能的代谢物,其分布广泛,已在500多种植物中发现有晶体的存在。晶体形态多样,有针晶、柱晶、棱晶、砂晶、簇晶等;类型丰富,有草酸钙晶体、钟乳体、硅质体、硫酸钙晶体及其它类型的晶体;功能特殊,具有钙调节、植物保护和防御、重金属解毒、离子平衡、缓解逆境胁迫及其它多种生物功能。晶体的形成涉及钙离子的体外吸收和体内转运,草酸的生物合成,以及钙离子和草酸的耦合过程;晶体的生长发育涉及液泡、晶异细胞的调控及与其它细胞结构的相互协作。对晶体的研究进行综述,以期为晶体的进一步研究提供基础资料。     

The flora and biogeochemistry of the ultramafic soils of Goiás state, Brazil

Major collections of the ultramafic flora of Goiás, central Brazil, were made by Brooks and co-workers in 1988 and 1990. At the time of reports on this material in 1990–1992 much of it had been identified only tentatively and incompletely, but the area was clearly interesting for taxonomic and biogeochemical reasons. Further progress has been made but still only two-thirds of the specimens are identified at the species level. Following a third collection in early 2005, we now have 800 specimens from this area, with chemical analyses of all the plants and of more than 120 representative soil samples. New species have been found, e.g., in Paspalum (Poaceae) and Pterolepis (Melastomataceae). There is a need for more taxonomic work in genera such as Cnidoscolus (Euphorbiaceae), Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and Vellozia (Velloziaceae). Ni hyperaccumulation (>1,000 mg/kg in dry plant matter) has now been found in a total of 79 specimens, representing more than 30 different species. Notable Ni hyperaccumulators include Pfaffia sarcophylla (Amaranthaceae), species of Justicia, Lophostachys and Ruellia (Acanthaceae), Porophyllum (Asteraceae), several species of Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and a possibly new Cnidoscolus (Euphorbiaceae). Ni hyperaccumulation has not been found in plants of the outcrops of Morro Feio or Crominia-Mairipotaba; it seems to be confined to the extensive layered ultramafics of Barro Alto and the Macedo-Niquelandia areas. The distribution of Ni-values in the Brazilian plant collection is different from that found in the Mediterranean and California, where there is a clear distinction between accumulator and non-accumulator plants: in Brazil the distribution is more continuous, and median Ni concentrations are much greater. An ultramafic hill just north of Niquelandia deserves to be protected because of the presence there of many of the hyperaccumulators and species probably endemic to the Goiás ultramafics.     

A morphologic and genetic analysis of Littorina saxatilis (Prosobranchia) from Venice, and on the problem of saxatilis—rudis nomenclature

Shell morphology and allozyme patterns of 17 enzymes are analysed within the isolated population of L. saxatilis Olivi (1792) from Venice, the type locality of the species. The shell morphology is compared to three different L. saxatilis phenotypes from Sweden, and showed to be similar to the brackish water 'tenebrosa' type. The Venice population is genetically more distant from British and Swedish populations than are the latter from each other. Less variability (heterozygosity) within the Venice compared to the Atlantic populations is probably a consequence of random genetic drift during a period of small population size.
The nomenclature of L. saxatilis in the Atlantic is discussed and it is suggested that until the exact taxonomic relationship between the Mediterranean and the Atlantic populations has been confirmed by, for example, cross-breeding experiments, the name 'saxatilis' should be kept for the non-Venetian populations (described by Maton (1797) under the name 'rudis').     

The Isolation and Properties of Oxalate Crystals from Plants

A method of isolation of crystalline inclusions of plant cellsis described. The crystals consist mainly of calcium oxalatein plants grown under normal conditions, but when calcium isreplaced by magnesium, barium, or strontium in the culture solutionthese elements substitute for calcium in the crystals; evenunder normal conditions magnesium occurs in the crystals tothe extent of about 2 per cent. The crystal morphology vanesin the species examined from raphides to complex conglomeratesand X-ray diffraction demonstrates an association of raphideswith calcium oxalate monohydrate whilst other solitary formsand conglomerates are associated with calcium oxalate 2.25H₂O.On this basis the species examined can be divided mto threegroups.     

A cytotaxonomic study of some Australian species of Drosera L. (Droseraceae)

KONDO, K. & LAVARACK, P. S., 1984. A cytotaxonomic study of some Australian species of Drosera L. (Droseraceae). Karyomorphological comparisons of 15 species of Australian Drosera are presented along with 11 new chromosome counts. In Australia the genus forms an extensive aneuploid series. The species which have chromosome numbers from n =10 to n = 19 show large chromosomes, while those which have chromosome numbers more than 20 show small chromosomes. Drosera paleacca shows the lowest chromosome number in the genus, 2 n = 10, with 10 large chromosomes, indicating a new basic number, x = 5. The non-staining gap between the chromatids of each chromosome is rather wide and their centromeric region is not seen throughout prophase, prometaphase, and metaphase. The C-banding and silver-staining analyses in Drosera petiolaris chromosomes suggest that Drosera chromosomes could have diffuse centromeres and simplified C-segments. Some taxonomic implications are considered, notably the possible removal of Drosera banksii from Drosera section Ergaleium to Drosera section Lasiocephala and the reduction to synonymy of Drosera section Prolifera .     

Similarity in yolk-platelet structure of an ancient bony fish (Acipenser) and an ancient reptile (Sphenodon)

Lipovitellin-phosvitin crystals from oocytes of the sturgeon (Acipenser boeri L.) and the tuatara (Sphenodon punctatus [Gray]) have been shown to he orthorhombic like all such known crystals from vertebrates higher than cyclostomes. Lattice parameters and projected crystal views also resembled closely the hitherto known cases. The high evolutionary conservation of this crystal structure probably reflects a cell-biological significance of the tertiary structure of crystal constituents, especially of the lipovitellines. A comparative consideration of crystallographic data from cyclostomes and higher vertebrates suggests that cyclostomes started with one species and all higher vertebrates with two species of lipovitellin molecules.     

Molecular phylogeny of the genus Dahlia Cav. (Asteraceae, Heliantheae-Coreopsidinae) using sequences derived from the internal transcribed spacers of nuclear ribosomal DNA

Sequences of the internal transcribed spacers (ITS) of the 18S-26S nuclear ribosomal DNA were used to resolve phylogenetic relationships among 13 species of the genus Dahlia . Phylogenetic reconstruction from both parsimony analysis and pairwise distance data produced a single tree in which four clades could be distinguished, these broadly separating the species into the different chromosome numbers found in Dahlia ( x = 16, x = 17 and x = 18). Although species based on x = 16 were divided into two clades, there is the suggestion that this separation may be artificial and that these should be combined as a single clade. The phylogeny produced here has been discussed with reference to the existing taxonomic treatment of the genus. It currently appears that the genus Dohlia is monophyletic and it is evident that the different basic chromosome numbers withim the dysploid series in Dahlia have evolved only once. This proposed monophyly of the genus coupled with the successful production of hybrids withim the dysploid series (2 n = 32, 2 n = 34 and 2 n = 36) suggests that the species of Dahlia have evolved from a common ancestor.     

Diversity and distribution of idioblasts producing calcium oxalate crystals in Dieffenbachia seguine (Araceae)

Although cells that synthesize crystals are known throughout the plant kingdom, their functional significance is still unknown. Mechanical support, mineral balance, waste sequestration, and protection against herbivores have all been proposed as crystal functions. To seek clues to their role(s), I systematically examined all organs except fruit of Dieffenbachia seguine (Araceae) for crystals. Crystals were found in nearly every organ. Raphides (long, slim, pointed crystals) were most common, but druses (crystal aggregates) and prisms were also found. Raphides varied in size by a factor of 10 and also in organization from tightly bundled to loosely organized. Biforines, a type of cell capable of expelling raphides, or biforine-like cells, were found in nearly all organs, but especially in leaves, spathes, and anthers. Different organs had different crystal complements, and characteristic crystals were found at specific locations, such as among pollen, along the undersides of leaf veins, and at root branch points. All crystals appeared to be composed of calcium oxalate, based on acid solubility. Possible roles of the crystals are discussed in light of these findings.     

Ecdysteroids from Vitex species: distribution and compilation of their 13C-NMR spectral data

Iridoids and ecdysteroids are found in some genera of the family Verbenaceae. In such cases, they are used as chemotaxonomic markers for the difficult task of taxonomic identification by using morphological characteristics of plants belonging to this family. The present work describes the distribution of ecdysteroids in plants from the genus Vitex from a review of previous work on seventeen Vitex species. In addition, (13)C-NMR data of the main ecdysteroids found in this genus are described. This study attempted to summarize previous research on ecdysteroids distribution in Vitex species with the addition of (13)C-NMR analysis to further refine the characterization of these compounds in the Verbenaceae family.     

天津盐渍化生境54种植物钙晶体与钙组分特征

植物钙包括游离态的Ca²⁺和结合态易溶、微溶和难溶于水的钙盐,而难溶于水的钙盐常会形成钙晶体.为了解盐渍化生境中不同生长型植物体内的钙状况,本文对天津市54种植物进行了钙晶体的镜检和钙组分的测定.结果表明： 在盐渍化生境中的54种植物体内,有38种植物体内镜检到较多的钙晶体,其中37种植物体内为以簇晶和方晶为主的草酸钙晶体,只在桑科的无花果叶片中观察到内含碳酸钙晶体的钟乳体.按生长型统计,落叶乔、灌木体内的草酸钙晶体较多,藤本植物体内的草酸钙晶体较少,而草本植物和常绿乔木体内未镜检到草酸钙晶体.同时,从乔木、灌木、藤本到草本,植物体内盐酸溶性钙含量逐渐减少而水溶性钙含量逐渐增多,且草本植物体内的水溶性钙含量显著高于乔木和灌木.在盐渍化生境中,植物体内的钙晶体和钙组分因生长型不同而有所差异,草酸钙在落叶乔、灌木抵御盐分胁迫中发挥着重要作用.     

Calcium oxalate crystals in plants

Calcium (Ca) oxalate crystals occur in many plant species and in most organs and tissues. They generally form within cells although extracellular crystals have been reported. The crystal cells or idioblasts display ultrastructural modifications which are related to crystal precipitation. Crystal formation is usually associated with membranes, chambers, or inclusions found within the cell vacuole(s). Tubules, modified plastids and enlarged nuclei also have been reported in crystal idioblasts. The Ca oxalate crystals consist of either the monohydrate whewellite form, or the dihydrate weddellite form. A number of techniques exist for the identification of calcium oxalate. X-ray diffraction, Raman microprobe analysis and infrared spectroscopy are the most accurate. Many plant crystals assumed to be Ca oxalate have never been positively identified as such. In some instances, crystals have been classified as whewellite or weddellite solely on the basis of their shape. Certain evidence indicates that crystal shape may be independent of hydration form of Ca oxalate and that the vacuole crystal chamber membranes may act to mold crystal shape; however, the actual mechanism controlling shape is unknown. Oxalic acid is formed via several major pathways. In plants, glycolate can be converted to oxalic acid. The oxidation occurs in two steps with glyoxylic acid as an intermediate and glycolic acid oxidase as the enzyme. Glyoxylic acid may be derived from enzymatic cleavage of isocitric acid. Oxaloacetate also can be split to form oxalate and acetate. Another significant precursor of oxalate in plants is L-ascorbic acid. The intermediate steps in the conversion of L-ascorbic acid to oxalate are not well defined. Oxalic acid formation in animals occurs by similar pathways and Ca oxalate crystals may be produced under certain conditions. Various functions have been attributed to plant crystal idioblasts and crystals. There is evidence that oxalate synthesis is related to ionic balance. Plant crystals thus may be a manifestation of an effort to maintain an ionic equilibrium. In many plants oxalate is metabolized very slowly or not at all and is considered to be an end product of metabolism. Plant crystal idioblasts may function as a means of removing the oxalate which may otherwise accumulate in toxic quantities. Idioblast formation is dependent on the availability of both Ca and oxalate. Under Ca stress conditions, however, crystals may be reabsorbed indicating a storage function for the idioblasts for Ca. In addition, it has been suggested that the crystals serve purely as structural supports or as a protective device against foraging animals. The purpose of this review is to present an overview of plant crystal idioblasts and Ca oxalate crystals and to include the most recent literature.     

MORPHOLOGY AND DISTRIBUTION OF COLLETERS AND CRYSTALS IN RELATION TO THE TAXONOMY AND BACTERIAL LEAF NODULE SYMBIOSIS OF PSYCHOTRIA (RUBIACEAE)

Earlier investigators established that a finger-like colleter with elongate axial cells and a palisade epidermis is the standard type in the Rubiaceae. This type, with some variation, also prevails in Psychotria, based on a worldwide anatomical survey of vegetative buds from herbarium specimens of 296 species (about 50 % of total). It is virtually the only type found outside of continental Africa. Among African species, it is most common in subgenus Psychotria, with mostly nodule-free species. In subgenus Tetramerae, with only leaf-nodulated species, there is a strong tendency toward brushlike and dendroid colleters in which epidermal cells are extremely elongate and separated from each other. It is speculated that this change in colleter morphology associated with presence of nodule bacteria may be correlated with a change in secretion product more suitable for support of bacteria. Three morphological forms of crystal occur: raphides, styloids, clustered crystals. They may occur singly or in combination. Several patterns and trends were noted in crystal distribution that could be of taxonomic significance.     

Macromolecular impurities and disorder in protein crystals.

The mechanisms by which macromolecular impurities degrade the diffraction properties of protein crystals have been investigated using X-ray topography, high-resolution diffraction line shape measurements, crystallographic data collection, chemical analysis, and two-photon excitation fluorescence microscopy. Hen egg-white lysozyme crystals grown from solutions containing a structurally unrelated protein (ovotransferrin) and a related protein (turkey egg-white lysozyme) can exhibit significantly broadened mosaicity due to formation of cracks and dislocations but have overall B factors and diffraction resolutions comparable to those of crystals grown from uncontaminated lysozyme. Direct fluorescence imaging of the three-dimensional impurity distribution shows that impurities incorporate with different densities in sectors formed by growth on different crystal faces, and that impurity densities in the crystal core and along boundaries between growth sectors can be much larger than in other parts of the crystal. These nonuniformities create stresses that drive formation of the defects responsible for the mosaic broadening. Our results provide a rationale for the use of seeding to obtain high-quality crystals from heavily contaminated solutions and have implications for the use of crystallization for protein purification. Proteins 1999;36:270-281.     

The Bornean Lithocarpus B1. section Synaedrys (Lindl.) Barnett (Fagaceae): its circumscription and description of a new species

The Bomean species of Lithocarpus B1. section Synaedrys edl.) Barnett (Fagaceae) are discussed in terms of their unifying characteristics, and keys to the species are provided. A novel morphological feature present in the genus, where the seed in the mature fruit is enclosed by a lignified and thickened receptacle, is illustrated. A new species, L palungensis Cannon & Manos, is described. It can be distinguished from L. pulcher (King) Markgr. by its submontane distribution, prominent reflexed cupular spines, present at all stages, and broadly oblong leaves with scattered open fasciculate trichomes on the abaxial surface. Foliar trichome types present within the section are also described. Distinctiveness of fruit wall and receptacle shape, as described by two-dimensional elliptic Fourier transformation, is demonstrated by principal components analysis.     

Mobile organisms in a geologically complex area: Lepidoptera in the Indo-Australian tropics

The Indo-Australian tropical archipelagos have increased in extent and proximity through the Tertiary whilst also changing their configuration. The development of new land areas between old cratonic ones involves extensive dispersals of plants and animals from the latter to the former. The vicariance approach, though suited to the study of the fragmentation of old, cratonic land areas, is of uncertain value in this situation; the representation of emergence or convergence and fusion of land areas in cladogram form presents immense problems and to attempt it may be pointless.
Distribution of Lepidoptera species largely reflects the present day geography of the area for both lowland and montane habitats. Significant discordances at a higher taxonomic level can be examined in the light of hypotheses of past geography such as those concerning the evolution of the Melanesian Arcs.
There are many advantages and some disadvantages in using Lepidoptera for such studies, involving their taxonomy, completeness of geographical coverage, range of dispersal ability and specificity to environmental conditions. Both cladistic and phenetic methods can provide basic data for biogeographic studies. The importance of an understanding of habitat preferences is stressed.
Patterns of probable recent development involving well-defined groups of very similar species are examined in the hope they will provide a yardstick whereby potentially older patterns can be assessed, and lead in time to methodology that will satisfy the stringent requirements of current thinking in the philosophy of science.     

OCCURRENCE,TYPE, AND LOCATION OF CALCIUM OXALATE CRYSTALS IN LEAVES AND STEMS OF 16 SPECIES OF POISONOUS PLANTS

Crystals in 16 species of poisonous plants growing naturally in Saudi Arabia were studied with light microscopy. Three types of crystals were observed: druses, prismatics, and crystal sand. Raphides and styloids were not observed in any of the species studied. Druses occur more frequently in the leaf midrib and in the cortex and pith of the stem. In contrast, crystal sand and prismatic crystals are rare and occur in the leaf, intercostal lamina, and in the vascular tissues. The preliminary results show the absence of the three types of calcium oxalate crystals in the stem and leaf of seven species: Ammi majus L., Anagallis arvensis L., Calotropis procera Ait., Citrullus colocynthis (L.) Schard, Euphorbia peplis L., Hyoscyamus muticus L., and Solarium nigrum L., and the presence of druses, prismatic crystals, and crystal sand either in the leaf and stem or in the leaves or stems of nine species: Anabasis articulata (Forssk.) Moq. in DC., Chenopodium album L., Convolvulus arvensis L., Datura stramonium L., Nerium oleander L., Ricinus communis L., Rumex nervosus Vahl., Pergularia tomentosa L., and Withania somnifera (L.) Dun. in DC. These observations indicate that there is no apparent relationship between the distribution of calcium oxalate crystals and the toxic organs of the plants, and supports the view that the presence of calcium oxalate crystals may not be related to plant toxicity.     

红豆草中含晶细胞的形态学研究

红豆草（Ｏｎｏｂｒｙｃｈｉｃｖｉｃｉａｅｆｏｌｉａｓｃｏｐ．）植株的所有器官中都分布有含晶细胞,其结晶的类型主要为棱晶,此外还有砂晶。在营养器官中,含棱晶的细胞主要分布在维管组织之中或外围。横切面上,棱晶则几至几十块纵列成行存在,且常伴生于韧皮纤维旁,但每块棱晶各有一分室隔开;在茎的表皮下偶有与大型粘液细胞伴生的砂晶。花萼的表皮中偶有棱晶,花瓣表皮及雄蕊药隔中有砂晶;子房壁内表皮下一层细胞逐渐发育成含棱晶的连续细胞,同时子房维管组织中也形成大量棱晶。分析表明,结晶成分为草酸钙。     

Taxonomic, evolutionary and ecological implications of the leaf anatomy of rhizomatous Iris species

The leaf anatomy of the rhizomatous Iris species with ensiform leaves and the related genera Pardanthopsis and Belamcanda is described. Their isobilateral leaves may or may not have a pseudo-dorsiventral structure. Variable characters of their leaf blades include: outline in transverse section, height and shape of papillae, form and structure of stomata, transverse section outline of marginal fibre strands and sclerenchy matous inner bundle sheath at phloem and xylem poles, forms of mesophyll arrangement, mesophyll structure and air canals, vascular bundle arrangement and the detailed structure of the larger vascular bundles, distribution of tannin, size and distribution of crystals. The taxonomic and ecological significance of these characters has been evaluated.
The anatomical characteristics of 25 supraspecific taxa in three genera are presented and compared in tables. The relationships and evolutionary position of these taxa are discussed. Each of the three subgroups within Iris appears to be correlated with a syndrome of anatomical characters. Some species currently of uncertain taxonomic position are discussed, and their classification based on anatomical data is suggested.
Some characters related to xeromorphy or helomorphy are mentioned.     

Plant calcium oxalate crystal formation, function, and its impact on human health

Crystals of calcium oxalate have been observed among members from most taxonomic groups of photosynthetic organisms ranging from the smallest algae to the largest trees.The biological roles for calcium...