Lipoidal Substances Research Articles

Neither nectar nor deception: the role of floral rewards in the pollination system of Laelia (Orchidaceae: Laeliinae).

Orchids offer a variety of floral rewards to pollinators. In many orchid groups, however, the transfer of pollen is based on food-deception, as in the case of Laelia (including Schomburgkia s.s.), a genus assigned to the Neotropical subtribe Laeliinae. Here, we report on the reproductive biology of a Brazilian member of this subtribe, namely, Laelia gloriosa, occurring in the forested areas of southeastern Brazil. The study includes analyses of floral morphology, histochemistry, and the chemical analysis of floral rewards and scents. Pollinators and pollination mechanism data were collected in the field by means of focal observations. Analyses of breeding systems and the percentage of potentially viable seed were also recorded. The floral morphology of Laelia gloriosa indicates that this species is melittophilous. The flowers release a citrus-like fragrance that attracts many species of bee. The flowers offer waxy material as a reward, and this is collected exclusively by Meliponini bees. Several bee species visit the flowers. However, those of L. gloriosa are pollinated exclusively by Trigona spinipes. Pollinaria are deposited on the bee's scutellum. Plants of the studied population were entirely self-compatible, but pollinator-dependent. The frequency of visits to these flowers was greater than in rewardless Laeliinae. Our study provides the first evidence of lipoidal substances as a resource in Laeliinae. The discovery that an orchid species (Laelia gloriosa) of this subtribe, hitherto considered to be entirely pollinated by nectar-seeking pollinators, offers a floral waxy material and provides new insights into the evolution of this important subtribe.

Study of the reproductive biology of an Amazonian Heterotaxis (Orchidaceae) demonstrates the collection of resin-like material by stingless bees

Tropical and subtropical plants provide to pollinators a range of nutritive and non-nutritive materials as alternative to pollen and nectar, including resins, which are gathered by females of several groups of social and solitary bees. Although resin-like material has previously been recorded in Maxillariinae, these investigations generally did not present data relating to pollinators. In fact, the collection of resins has never been recorded elsewhere in orchids. The aim of this paper was to provide a detailed study of the reproductive biology of an Amazonian Heterotaxis, H. superflua, based on records of flowering phenology, floral morphology, pollinator behavior and breeding system. Heterotaxis superflua offers resin-like material to pollinators and is pollinated by a single species of stingless bee. The resin is a heterogeneous material rich in mucilage, starch and sugars, while lipoidal substances occur as small droplets. Chemical analyses confirm the presence of sugar, which explain the presence of reducing sugars and mucilage detected in the histochemical investigations. Our data also showed the Heterotaxis is self-compatible and pollinator dependent. This study demonstrates for the first time the collection of resin-like material in orchids. The gathering of resin is frequently associated with the nest construction, since this material is considered to be a water-repellent and has anti-pathogen chemical properties. Despite offering of a floral reward, fruit set under natural conditions is lower than for experimental pollinations, suggesting limited pollen flow within the population.

Pollinator‐independent orchid attracts biotic pollinators due the production of lipoidal substances

Flowering plants often depend on the attraction of biotic pollinators for sexual reproduction. Consequently, the emergence and maintenance of selected floral attributes related to pollinator attraction and rewarding are driven by pollinator pressure. In this paper we explore the effect of pollinators, rainfall, temperature and air humidity on the reproduction of a Brazilian terrestrial orchid, Cranichis candida based on data of phenology, flower resources, olfactory and visual attraction cues, pollinators and breeding system. The flowers of C.candida are strongly protandrous and pollinated by workers of the social native bee Tetragonisca angustula. The bees collect labellar lipoidal substances (wax scales), which are transported to the nest. The lipoidal substance is composed of sterols, hydrocarbons and terpenes. The last presumably protects the bees and their nests against pathogens and other arthropods. C.candida sets fruits through biotic self- and cross-pollination, and spontaneously due the action of raindrops on flowers. Our results indicate that in C.candida, although rain-mediated spontaneous self-pollination happens, fructification mediated by biotic pollinations also occurs, which may result in fruit set by cross-pollination. A mixed pollination system must result in higher genetic variability when compared to species whose fruits are produced entirely by self-pollination. On the other hand, autogamy is a form of reproductive assurance, and has commonly evolved where pollination services are rare or absent.

Comparative reproductive biology and pollinator specificity among sympatricGomesa(Orchidaceae: Oncidiinae)

The incredible pollination mechanisms displayed by orchid flowers has inspired biologists over the centuries. Based on the intriguing flower structures, the relationship among orchid species and their pollinators has been frequently regarded as very specialised. Given that visits on flowers pollinated by oil-collecting bees are regularly rare, and in Oncidiinae the flowers frequently attractexclusively species that act as effective pollinators, the comparative reproductive biology and pollinator specificity of two sympatric Gomesa (G.varicosa and G.montana; Oncidiinae) were analysedbased on records of floral morphology, production of floral rewards, pollinators and pollination mechanisms. Furthermore, experimental pollinations were carried out in order to examine the breeding systems. The results have show that in the studied population, both Gomesa are visited by several bee species, but these orchids present a specific pollination system.Pollinaria are deposited on the head of Centridini (G.varicosa and G.montana) and Epicharitini (G.varicosa) bees when landed on the central callus of the labellumto collect lipoidal substances produced by glandular elaiophores on lateral lobes of the labellum. Both species are dependent on a biotic pollen vector to set fruits. Gomesamontana is completely self-incompatible, while G.varicosa is partially self-compatible. Our results indicate that although the occurrence of self-sterile species seems to be common in Oncidiinae, in partially self-incompatible species, as is the case of G.varicosa, self-compatibility has been considered as an important factor favouring reproductive assurance in populations with low visitation frequencies, despite occurrence of inbreeding depression.

Calcium-Activated Potassium Channels in the Malaria Parasite Erythrocyte Cycle

Free calcium (Ca2+) is involved in the Apicomplexan parasite Plasmodium falciparum cycle of development, both at the time of invasion and at the time of egress from host erythrocytes. We hypothesized that the two prominent and transient erythrocyte crenation events (echinocytosis), one shortly following parasite invasion and one immediately preceding parasite egress, result from the activation of a calcium-dependent potassium channel, the Gardos channel (KCNN4 / KCa3.1), native to the red blood cell (RBC) and resident in its plasma membrane.To test if a Ca2+-dependent K+ flux (followed by water) causes the observed post-invasion RBC echinocytosis, parasite invasion was observed and quantified using RBC loaded with a Ca2+ chelator (BAPTA-AM) in a new light microscopy invasion assay. We confirmed that neither invasion nor the subsequent RBC echinocytosis were affected. Furthermore, RBC were treated with several inhibitors of Gardos channels, prior to and during parasite invasion. Again, no adverse effect on invasion or echinocytosis was observed. Finally, high external KCl that eliminates the potassium gradient across the RBC membrane did not inhibit the post-invasion RBC echinocytosis. Thus, it is unlikely that activation of the Gardos channel explains the echinocytosis of RBC following parasite invasion. While exploring the effect of calcium free medium on invasion, we found that it is often aborted but still leads to echinocytosis. Contrary to invasion in the presence of calcium, echinocytosis after abortive invasion is not reversed and often leads to RBC hemolysis.We conclude that alternative calcium independent mechanisms, such as the modification of the RBC cytoskeleton or the sudden incorporation of lipoidal substances secreted during invasion by the P. falciparum merozoite, and their effect on RBC curvature stress may explain the observed echinocytosis.

Developmental and Cytochemical Features of Male Reproductive Organ in <i>Crataegus tanacetifolia</i> (Lam.) Pers.

In this study, the development of male reproductive organ was analysed in Crataegus tanacetifolia (Lam.) Pers., endemic to Turkey. Androecium is composed of 20 stamens which are attached at the base of the filaments. The anther wall formation follows the dicotyledonous type. The undifferentiated anther is ovoid-shaped, and the differentiation starts with the appearance of archesporial cells. Mature anthers are dorsifix and tetrasporangiate. The anther wall is composed of an epidermis, endothecium, two or three rows of middle layers and secretory tapetum. Endothecial cells show fibrous thickening. Tapetum is characterized by enlarged secretory types with binucleate cells, which presented an intense reaction with regard to proteins, insoluble polysaccharides and lipids. Features of chromatin condensation and nucleus disorders identified with the application of DAPI (4´,6-diaminido-2-phenylindole) point out programmed cell death. Epidermal and endothecial layers remain intact until anther dehiscence; however, middle layer and tapetum disappear during development. At the end of regular meiotic division, tetrahedral microspore tetrads are formed. Pollen grains are tricolparatae, tectate and sphaeroidea. Exine is made up of lipoidal substances and proteins, but the intine includes insoluble polysaccharides. Further, cytoplasm of pollen grains are rich in proteins, lipids and insoluble polysaccharides.

Cytochemical and ultrastructural observations of anthers and pollen grains in Lathyrus undulatus Boiss

Cytochemical and ultrastructural observations of anthers and pollen grains inLathyrus undulatusBoissInLathyrus undulatusBoiss. (Fabaceae), the young microspore stage of anther development was characterized by the enlarged secretory tapetal cells, which presented an intense reaction with regard to protein, insoluble polysaccharides and lipids. At bicellular pollen stage, the middle layer and the tapetum degenerated. After degradation of the tapetum, epidermis and single row U-shaped endothecium existed in the mature anther wall, and pollen grains remained in the locus. Young microspores had a spherical and centrally located nucleus with one or two nucleoli, many spherical lipid bodies and starchy plastids. A mature pollen grain contains insoluble polysaccharides, proteins, lipids and calcium. The mature pollen had the following morphological characteristics: 3-zonocolporate, prolate, tectate (imperforate) type of exine and perforate type of structure. The intine formed an important constituent portion of the wall, and consisted two sublayers: an outer intine (exintine) and an inner intine (endintine). The well-defined exine was made up of lipoidal substances and protein, but the intine composed of insoluble polysaccharides and protein. The bicellular state of the pollen grains persisted to anthesis.

Coenzyme Q and Vitamin E Interactions

Coenzyme Q or ubiquinone (CoQ) plays several functional roles in cellular processes, among which the most well-recognized is the translocation of protons across the inner mitochondrial membrane and the transfer of electrons from oxidoreductases, such as NADH-Q-, succinate-Q-, α-glycerophosphate-Q-, and dihydroorotate-Q-oxidoreductase, to Q-cytochrome c oxidoreductase in the mitochondrial electron transport chain. CoQ and vitamin E or α- tocopheral are lipoidal substances, present within the hydrophobic domain of the phospholipid bilayer of cellular membranes. CoQ exists in three alternate redox states—namely, fully oxidized or ubiquinone (Q); partially reduced, ubisemiquinone (·QH), which is a free radical; and fully reduced or ubiquinol (QH 2 ). In vivo interaction between CoQ and α- tocopherol is indicated by the increase in α-tocopherol content of mitochondria in response to CoQ intake; however, α-tocopherol intake has no effect on CoQ content. Mitochondrial augmentation with α-tocopherol in vivo and in vitro results in a decrease in the rate of O 2 · -generation by submitochondrial particles (SMPs). This relationship may be because of a “sparing/regeneration” effect of CoQ on α-tocopherol that is supported by (1) in vitro studies showing that CoQ can react with tocopheroxyl radicals to regenerate α-tocopherol, (2) the fact that loss of α-tocopherol in the mitochondrial membranes is progressively stemmed by elevation of the molar ratio of CoQ to α-tocopherol, (3) the fact that the reactivity of ubiquinol with peroxyl radicals is much lower than that of α-tocopherol, and (4) the fact that elevation in CoQ level in mitochondria by dietary supplementation is linked to a corresponding rise in α-tocopherol content.

Designing Anticancer Drugs via the Achilles Heel: Ceramide, Allylic Ketones, and Mitochondria

Published reports are reviewed as the basis of a proposal that an effective antineoplastic drug should contain several features: (a) resemblance to the natural lipid, ceramide; (b) an allylic alcohol and/or allylic ketone moiety; (c) a hydroxyl and/or a nitrogen atom near the allylic group; (d) conjugated double bonds as part of the allylic region. The drug should produce reactive oxygen species in tumor mitochondria, stimulate the generation of ceramide in the tumor, and condense with mitochondrial glutathione. It is pointed out that some antibiotics with these features are also active against cancer cells; perhaps anticancer drugs with these features will prove useful as antibiotics. Common problems in working with lipoidal substances are discussed.

Vessel occlusion and secretory activities of vessel contact cells in resistant or susceptible cotton plants infected with Fusarium oxysporum f.sp. vasinfectum

An ultrastructural and histochemical examination of secondarily infected and adjacent, uninfected vessels and associated contact cells was conducted in resistant and susceptible cotton plants following inoculation with Fusarium oxysporum f.sp. vasinfectum. Contact cells showed an increase in cytoplasmic content and activity. These contact cells produced lipoidal substances and other compounds that were apparently secreted into vessels through pits. The secretion products coated vessel walls and accumulated in vessel lumens in a variety of forms, from amorphous aggregates to vesicular structures with different sizes and shapes. The fungus in secondarily infected vessels was embedded in or coated by these secretion products. Accumulations of secretion products completely blocked the vessel lumens. The accumulation of the secretion products in vessel lumens and the development of the wall coating were more intensive in resistant cv Seabrook Sea Island than in susceptible Rowden. This more intensive secretory activity of contact cells in resistant plants resulted in the formation of barriers that may contribute to chemical inhibition and physical restriction of the fungus within vessels and prevention of its spread.

Lipid in wall and cytoplasm ofSolidagopollen

Abstract After fixation of mature pollen of Solidago canadensis in osmium tetroxide evidence for lipids on and in the exine and in the cytoplasm was similar to what can be seen with the light microscope in fresh pollen, whereas there was relatively little evidence for lipids after glutaraldehyde fixation or the common method using glutaraldehyde followed by osmium tetroxide. We have used a simple method for the detection of lipoidal substances on the pollen surface, in bacular interstices, and within the caveae. Our results show that the exine of caveate pollen has a large capacity for holding lipid. Cavea were lost (deflated) unless we exposed anthers to osmium tetroxide prior to methods which resulted in extraction of lipoidal materials; such methods included glutaraldehyde fixation followed by washing in buffer prior to osmium tetroxide.

Ultrastructure and histochemistry of lipoidal droplets in vessel contact cells and adjacent parenchyma cells in cotton plants infected by Fusarium oxysporum f.sp. vasinfectum

Osmiophilic droplets developed in contact cells and adjacent vascular parenchyma cells of cotton accompanied by changes in cytoplasmic organization after vessel infection by Fusarium oxysporum f.sp. vasinfectum. In the early stages of the cellular response to vessel infection, the droplets were observed in dilations of ER cisternac, the membrane envelopes of mitochondria, and occasionally the membrane envelopes of plastids and nuclei. As the cellular response to vessel infection proceeded and cytoplasmic reorganization became apparent, the droplets were associated with vesicles or remained as individual droplets within the cytoplasm. The developmental sequence suggests that the osmiophilic substances in these droplets may be secreted through the plasmalemma, infused into apposition layers, and exuded into the infected vessels through pits. Sudan Black B staining and organic solvent extraction indicate that the osmiophilic droplets are lipoidal in nature. It is suggested that the lipoidal substances are terpenoids that could function as phytoalexins.

Flocculation of Venereal Disease Research Laboratory reagent byHelicobacter pylori

Helicobacter pylori strains flocculated with Venereal Disease Research Laboratory (VDRL) reagent in a glass slide test. Other pathogenic bacterial and fungal strains were nonreactive. The specific VDRL reaction property of Helicobacter pylori indicates an affinity of the cells for lipoidal substances, and can be used as a diagnostic aid for species identification.

MPTP and brain oxidative stress

Coenzyme Q or ubiquinone (CoQ) plays several functional roles in cellular processes, among which the most well-recognized is the translocation of protons across the inner mitochondrial membrane and the transfer of electrons from oxidoreductases, such as NADH-Q-, succinate-Q-, α-glycerophosphate-Q-, and dihydroorotate-Q-oxidoreductase, to Q-cytochrome c oxidoreductase in the mitochondrial electron transport chain. CoQ and vitamin E or α- tocopheral are lipoidal substances, present within the hydrophobic domain of the phospholipid bilayer of cellular membranes. CoQ exists in three alternate redox states—namely, fully oxidized or ubiquinone (Q); partially reduced, ubisemiquinone (·QH), which is a free radical; and fully reduced or ubiquinol (QH2). In vivo interaction between CoQ and α- tocopherol is indicated by the increase in α-tocopherol content of mitochondria in response to CoQ intake; however, α-tocopherol intake has no effect on CoQ content. Mitochondrial augmentation with α-tocopherol in vivo and in vitro results in a decrease in the rate of O2·-generation by submitochondrial particles (SMPs). This relationship may be because of a “sparing/regeneration” effect of CoQ on α-tocopherol that is supported by (1) in vitro studies showing that CoQ can react with tocopheroxyl radicals to regenerate α-tocopherol, (2) the fact that loss of α-tocopherol in the mitochondrial membranes is progressively stemmed by elevation of the molar ratio of CoQ to α-tocopherol, (3) the fact that the reactivity of ubiquinol with peroxyl radicals is much lower than that of α-tocopherol, and (4) the fact that elevation in CoQ level in mitochondria by dietary supplementation is linked to a corresponding rise in α-tocopherol content.

製剤工夫による癌へのｔａｒｇｅｔｉｎｇ

The recent studies of cancer therapies toward drug targeting to tumor cells are reviewed. There are several problems in the approach of drugs to the tumor cells after administration such as the trans-port through normal tissues, the selectivity of tumor tissue, and the permeability through the membrane of the tumor cells. Many biocompatible materials have been attempted to be used to overcome these problems. Microspheres of proteins, lipoidal particles(liposomes and emulsions), and biodegradable artificial polymers are used as carriers to study passive targeting in body, and also membrane active materials in lipoidal substances are used to solve the insensitivity and the tolerance of tumor cells to antitumor drugs. Also the formulation design of drug using poly(lactic acid)microspheres is presented for the example of lymph targeting and controlled release to prevent tumor metastasis.

Histochemical studies on the vitellogenesis in a fairy shrimpStreptocephalus dichotomus Baird (Crustacea: Anostraca)

Histochemical characterisation of ooplasm and yolk granules in different stages of oocyte maturation in the ovary was made in the freshwater fairy shrimpStreptocephalus dichotomus. In stage I oocyte, the ooplasm is reactive to basic and acidic groups of protein, aromatic groups such as tryptophenyl and tyrosyl and sulphur containing substances. The other organic compounds include acid mucopolysaccharide and acidic lipids. In stage II oocyte, sudanophilic lipoidal substances appear coinciding with yolk formation. Stage III oocytes are characterised by the abundance of yolk granules which are rich in sulphated acid mucopolysaccharide as well as glycogen. Besides these, the presence of acid phosphatase activity in the ooplasm and nurse cell is also noticed and its functional role in relation to vitellogenesis is discussed.

Behavior of fluorescent granular perithelium (FGP) in cerebral cortex of SHR-SP rats under some conditions

The fluorescent granular perithelial cells (FGP) in control and experimental specimens of SHR-SP rats were studied with light and electron microscopes. The results obtained are as follows. The FGP in SHR-SP rats are localized along small cerebral vessels and provided with many irregularly shaped inclusion bodies. Their matrices are homogenous and relatively less dense. Sometimes, the FGP fall into degeneration and their cytoplasm shrinks and fills with small dense granules. Concomitantly, collagen fibers appear surrounding them. After feeding rats a fat-rich chow, lipoidal substances appear in intracellular granules of FGP at the light microscopical level. Electron microscopically, the FGP are swollen and their inclusion bodies vary in shape and content. Large inclusion bodies are composed of several middle-sized inclusion bodies with heterogenous matrices. Frequently, pale inclusion bodies are provided with intensely stained limiting membranes. These facts suggest an incorporation of fat into the FGP. With the administration of elastase, intracellular lipid decreases moderately and the FGP scarcely swell. The cytoplasm of FGP and the contents of inclusion bodies become defined and contrasty. From this evidence, elastase seems to facilitate a fat metabolism in FGP. Morphological and functional differences between FGP and other perivascular cells including pericytes, microglia, and mast cells are briefly discussed.

Cell-biology of ageing. 1. Isolation of gamma-ray induced ageing mutants of Neurosporacrassa and their preliminary characterizations

Based on conidial viability of Neurospora crassa, ageing mutants have been induced with the help of gamma-rays. At a culture age of 15 days the mutants had a conidial viability of 0–28% whereas in case of their wild type strain (Em A) it was 95%. Extensional growth behaviour, replication potentialities, biomass production capacity and accumulation of lipoidal substances by these strains have been investigated. From the results obtained it seems that more than one biological process is involved in cellular ageing phenomenon. Further studies are in progress.

Effects of Benefin Vaporizing from Soils on Tobacco (Nicotiana tabacum) Foliage

In closed vapor exposure chambers, foliar injury on tobacco (Nicotiana tabacumL. ‘Speight G-28’) seedlings was caused by vapors arising from soils in which technical grade benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine) or its commercially-formulated emulsifiable concentrate had been incorporated. The emulsifier alone did not cause injury. Dosages of the herbicide ranged from 0.84 to 6.72 kg/ha or 13.1 to 104.8 ppmw in the concentration in soils, and the lowest dosage was sufficient to induce the foliar injury. Leaves which developed during the exposure were markedly shortened, narrowed, and thickened, distorted in shape, and had an extremely poor lamina expansion and abnormal venation pattern. Severity of the foliar injury increased as the herbicide dosage and soil moisture increased, and as the soil organic matter content decreased. Leaves which were partially expanded before the exposure were affected much less. When exposed to vapors of14C-benefin, plant seedlings readily absorbed radioactive materials by its entire foliage including the stem tip with a few tiny developing leaves. More than half of the14C absorbed and adsorbed during a 3-day exposure was recovered by CHCl3wash of leaves and appeared to be retained by the wax and cutin layers, and also by lipoidal secretion substances of the numerous trichomes on the leaf surface. There was a small fraction of unabsorbed or loosely retained14C material on the surface of the leaves and stem tip, which was removed by water. That not recovered from H2O and CHCl3washes appeared to be distributed in the internal tissues. Little acropetal translocation appeared to occur from the expanded leaves toward the stem tip. There was no translocation of14C-benefin into roots of plants where only a single leaf was exposed to the radioactive vapors.

Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv. Dramatic (Compositae). II. Ultrastructure and histochemistry

Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv. Dramatic are initiated from a single epidermal cell outgrowth and develop through an anticlinal division and a series of periclinal divisions to form a biseriate multicellular structure. Cells of the young trichome contain a large nucleus with prominent nucleoli and few small cellular organelles. Prior to the secretory stage, numerous ribosomes, polyribosomes, and dictyosomes are present in a dense cytoplasm but most of the dictyosomes are lost as secretion commences. Plastids in the stalk cells senesce but in a different manner than those in the upper tiers of secretory cells. Lipoidal substances form in the degenerating plastids. Cell wall ingrowths and the deposition of a flocculent material in the primary cell wall characterize secretory hairs. In very old hairs cellular lysis takes place with mitochondria being the last cellular organelle to remain intact. The secreted material, which collects in a subcuticular space, appears to be a terpenoid. The function of this material is not known.