Floral nectar production in Helleborus foetidus: an ultrastructural study

Botany ◽  
2012 ◽  
Vol 90 (12) ◽  
pp. 1308-1315 ◽  
Author(s):  
J.L. Vesprini ◽  
E. Pacini ◽  
M. Nepi
Keyword(s):  
Cell Wall ◽  
Vascular Tissue ◽  
Proximal Part ◽  
Amorphous Structure ◽  
Small Cells ◽  
Outer Cell ◽  
Basal Region ◽  
Floral Nectar ◽  
Nectar Production ◽  
Helleborus Foetidus

The floral nectaries of Helleborus foetidus L. were studied using scanning and transmission electron microscopy, as well as light microscopy. Nectaries are tubular and consist of an external epidermis, a photosynthesizing parenchyma, large branches of vascular tissue, a nectar-producing parenchyma, and an internal epidermis. The external epidermis is characterized by thick outer walls and a thin cuticle. Cells of the photosynthesizing parenchyma are characterized by chloroamyloplasts. The nectar-producing parenchyma consists of small cells with lobed nucleus, several small vacuoles, and numerous undifferentiated elongated plastids. These cells contain lipid bodies, Golgi membranes, and rough endoplasmic reticulum and are connected by numerous plasmodesmata. Parenchyma cells around sieve elements contain some amyloplasts. The outer cell wall of the internal epidermis displays a central thinned area containing a depression. The cuticle is very thick with amorphous structure, especially evident in its proximal part. Secretion takes place only in the inner basal region of the nectary cup. The surface of the internal epidermis is devoid of secreting structures. Nectar is released by fracture of the cuticle and underlying cell wall; however, epidermal cell death is not apoptotic. This holocrine secretion is coupled with a more common merocrine secretion through which nectar accumulates in subcuticular spaces. This combined secretion mode produces an enriched “nectar soup” crucial for interactions with pollinators and yeasts during winter flowering.

scholarly journals Vegetative propagation of elite Eucalyptus clones as food source for honeybees (Apis mellifera); adventitious roots versus callus formation

2020 ◽  
Vol 67 (1-2) ◽  
pp. 83-97 ◽  
Author(s):  
Avi Eliyahu ◽  
Zvi Duman ◽  
Sara Sherf ◽  
Olga Genin ◽  
Yuval Cinnamon ◽  
...  
Keyword(s):  
Cell Wall ◽  
Adventitious Roots ◽  
Molecular Mechanisms ◽  
Callus Formation ◽  
Food Sources ◽  
Differential Staining ◽  
Outer Cell ◽  
Nectar Production ◽  
Root Cells ◽  
Cell Organization

Summer and autumn in Israel are highly arid with not enough plants in bloom offering nectar and pollen to support the local apiary. This leads to decline in colony health and honey production. To increase food sources for honeybees, we initiated a project to clone elite Eucalyptus trees exhibiting constant and rich blooming from late summer to early winter. We induced adventitious roots from cuttings of two mature Eucalyptus trees of which nectar production and honeybees’ attraction was measured: Eucalyptus brachyphylla and Eucalyptus x trabutii. During the rooting process, a high frequency of cylindrical callus formation instead of roots was obtained. To shed light on the inner anatomy of the callus chunks, we compared their cell organization and cell-wall composition to those of roots. Whereas in the root, cells were organized in circumferential symmetry, no symmetry was found in the callus. Instead, a more chaotic accumulation of meristematic-like cells with sporadic clusters of tracheary elements laid in different directions were observed. The outer cell layer of the callus often included swollen cells with thin cell walls. Most callus cells stained more strongly for cellulose and lignin than cells in the root meristem. In addition, specific antibodies to methylesterified and de-methylesterified pectin showed differential staining of callus vs. root cells indicating cell wall differences. Strikingly, roots were seen to differentiate from the chaotic cell organization of the callus, albeit at low rates. Further investigation of the cellular and molecular mechanisms underlying callus formation, are required.

The ultrastructure of the outer cell wall-layer ofChlorella mutants with and without sporopollenin

1981 ◽  
Vol 138 (1-2) ◽  
pp. 121-137 ◽  
Author(s):  
J. Burczyk ◽  
M. Hesse
Keyword(s):  
Cell Wall ◽  
Wall Layer ◽  
Outer Cell ◽  
Cell Wall Layer ◽  
Outer Cell Wall

The Ultrastructure and Ontogeny of Pollen in Helleborus Foetidus L

1968 ◽  
Vol 3 (2) ◽  
pp. 161-174
Author(s):  
P. ECHLIN ◽  
H. GODWIN
Keyword(s):  
Cell Wall ◽  
Tapetal Cell ◽  
Pollen Grains ◽  
Ultrastructural Level ◽  
Low Molecular Weight ◽  
Cell Organelles ◽  
Helleborus Foetidus ◽  
Ubisch Bodies ◽  
Ubisch Body ◽  
Development Proceeds

The ontogeny of the tapetum and Ubisch bodies in Helleborus foetidus L. has been examined at the ultrastructural level, and their development has been closely linked with that of the sporogenous cell and pollen grains. During development the tapetum passes through successive phases of synthesis, maturity and senescence, ending in complete dissolution. During the anabolic phase of growth, precursors of the Ubisch bodies are formed as spheroidal vesicles of medium electron density within the tapetal cytoplasm; they are associated with a zone of radiating ribosomes, which, as development proceeds, can clearly be seen to be situated on strands of endoplasmic reticulum. The callose special wall round the microspores and the tapetal cell wall now disintegrate and the pro-Ubisch bodies are extruded through the cell membrance of the tapetal cells, where they remain on the surface of the anther cavity and soon become irregularly coated with sporopollenin. Deposition of sporopollenin continues on the Ubisch bodies at the same time as upon the exines of the developing pollen grains. In both cases, the later stages of sporopollenin deposition are associated with electron-transparent layers of unit-membrane dimensions appearing in section as white lines of uniform thickness. Continuing deposition of sporopollenin leads to the formation of compound or aggregate Ubisch bodies. It is conjectured that the sporopollenin is synthesized from the compounds of low molecular weight released into the anther loculus by the breakdown of the callose special wall and the tapetal cell wall. The final stages of tapetal autolysis involve the disappearance of all the cell organelles. An attempt is made to relate the findings to those described in other recent studies on Ubisch body formation and to combine them in a common ontogenetic pattern.

A freeze-etch study of plant cell walls for ectodesmata

1974 ◽  
Vol 52 (9) ◽  
pp. 2033-2036 ◽  
Author(s):  
N. C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Leaf Tissue ◽  
Physicochemical Characteristics ◽  
Outer Cell ◽  
Plantago Major ◽  
Plant Cell Walls ◽  
Phaseolus Vulgaris L ◽  
Epidermal Cell Wall ◽  
Outer Cell Wall

Leaf tissue of Phaseolus vulgaris L. and Plantago major L. was prepared by the freeze-etch technique and examined in the electron microscope for the presence of ectodesmata. No structures analagous to ectodesmata observed with light microscopy could be found in freeze-etched preparations of chemically unfixed material or in material fixed only in glutaraldehyde. Objects appearing as broad, shallow, granular areas in the epidermal cell wall beneath the cuticle were observed in leaf replicas after fixation in complete sublimate fixative, the acid components of the sublimate fixative, or mercuric chloride alone. Because of their distribution and location, these objects can be considered analagous to ectodesmata observed by light microscopists. Because these areas occur only in chemically fixed walls and are localized within the walls in discrete areas, their presence supports the contention that ectodesmata are sites in the outer cell wall with defined physicochemical characteristics.

scholarly journals Spreading of a mycobacterial cell-surface lipid into host epithelial membranes promotes infectivity

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
CJ Cambier ◽  
Steven M Banik ◽  
Joseph A Buonomo ◽  
Carolyn R Bertozzi
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Immune Activation ◽  
Cholesterol Synthesis ◽  
Membrane Lipids ◽  
Preventive Therapy ◽  
Outer Cell ◽  
Surface Lipid ◽  
Epithelial Membranes ◽  
Outer Cell Wall

Several virulence lipids populate the outer cell wall of pathogenic mycobacteria. Phthiocerol dimycocerosate (PDIM), one of the most abundant outer membrane lipids, plays important roles in both defending against host antimicrobial programs and in evading these programs altogether. Immediately following infection, mycobacteria rely on PDIM to evade Myd88-dependent recruitment of microbicidal monocytes which can clear infection. To circumvent the limitations in using genetics to understand virulence lipids, we developed a chemical approach to track PDIM during Mycobacterium marinum infection of zebrafish. We found that PDIM's methyl-branched lipid tails enabled it to spread into host epithelial membranes to prevent immune activation. Additionally, PDIM’s affinity for cholesterol promoted this phenotype; treatment of zebrafish with statins, cholesterol synthesis inhibitors, decreased spreading and provided protection from infection. This work establishes that interactions between host and pathogen lipids influence mycobacterial infectivity and suggests the use of statins as tuberculosis preventive therapy by inhibiting PDIM spread.

scholarly journals Candida albicans phosphate transport, facilitating nucleotide sugar biosynthesis, contributes to cell wall stability.

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Maikel Acosta-Zaldivar ◽  
Wanjun Qi ◽  
Ning-Ning Liu ◽  
Joann Diray-Arce ◽  
Louise A. Walker ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Enzymatic Reaction ◽  
Phosphate Starvation ◽  
Reaction Rates ◽  
Outer Cell ◽  
Cell Wall Polysaccharides ◽  
Nucleotide Sugar ◽  
Structural Cell ◽  
Chitin Synthases

The Candida albicans high-affinity phosphate transporter Pho84 is required for normal Target of Rapamycin signaling, oxidative stress resistance and virulence of this fungal pathogen. It also contributes to C. albicans’ tolerance of two antifungal drug classes, polyenes and echinocandins. Echinocandins inhibit biosynthesis of a major cell wall component, beta-1,3-glucan. Cells lacking Pho84 were hypersensitive to other forms of cell wall stress beyond echinocandin exposure, while their cell wall integrity signaling response was weak. Metabolomics experiments showed that levels of phosphoric intermediates, including nucleotides like ATP and nucleotide sugars, were low in pho84 mutant compared to wild type cells recovering from phosphate starvation. Non-phosphoric precursors like nucleobases and nucleosides were elevated. Outer cell wall phosphomannan biosynthesis requires a nucleotide sugar,GDP-mannose. The nucleotide sugar UDP-glucose is the substrate of enzymes that synthesize two major structural cell wall polysaccharides, beta-1,3- and beta-1,6-glucan. Another nucleotide sugar, UDP-N-acetylglucosamine, is the substrate of chitin synthases which produce a stabilizing component of the intercellular septum and of lateral cell walls. Lack of Pho84 activity, and phosphate starvation, potentiated pharmacological or genetic perturbation of these enzymes. Our model is that low substrate concentrations of beta-D-glucan- and chitin synthases diminish enzymatic reaction rates and potentiate pharmacologic inhibitors to decrease the yield of their cell wall-stabilizing products. Phosphate import is not conserved between fungal and human cells, and humans do not synthesize beta-D-glucans or chitin. Hence inhibiting these processes simultaneously could yield potent antifungal effects with low toxicity to humans.

scholarly journals Changes in structure of red pepper (Capsicum annuum L.) seedlings shoots under aluminum stress conditions

2012 ◽  
Vol 60 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Agata Konarska
Keyword(s):  
Cell Wall ◽  
Capsicum Annuum ◽  
Red Pepper ◽  
Outer Cell ◽  
Aluminum Stress ◽  
Water Culture ◽  
Anatomical Features ◽  
Parenchyma Cells ◽  
Al Treatment ◽  
Outer Cell Wall

The seedlings of the red pepper (<i>Capsicum annuum</i> L.) cv. Trapez grown in water culture for a period of 14 days with Al (0, 10, 20 and 40 mg·dm<sup>-3</sup> AlCl<sub>3</sub>·6 H<sub>2</sub>O). Some morphological and anatomical features of red pepper shoots were analyzed. Reduction in height and diameter of stems as well as decrease in fresh mass of shoots were observed after Al-treatment. In the hypocotyl the thickness of cortex parenchyma layer and the size of their cells were reduced. The aluminum treatment resulted in the increased in thickness of the epidermis outer cell wall. Under Al stress in the cotrex and the central cylinder parenchyma cells were present numerous enlarge plastids which contained large grains of starch and dark little bodies which were possible aluminum deposits. They weren`t observed in control seedlings.

Silver nanoparticles (AgNPs) internalization and passage through the Lactuca sativa (Asteraceae) outer cell wall

2021 ◽  
Author(s):  
Sergimar Kennedy de Paiva Pinheiro ◽  
Thaiz Batista Azevedo Rangel Miguel ◽  
Marlos de Medeiros Chaves ◽  
Francisco Claudio de Freitas Barros ◽  
Camila Pessoa Farias ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Cell Wall ◽  
Lactuca Sativa ◽  
Outer Cell ◽  
Outer Cell Wall

Radioautographic and Chemical Studies of Incorporation into Sycamore Vascular Tissue Walls

1968 ◽  
Vol 3 (1) ◽  
pp. 71-80
Author(s):  
F. B. P. WOODING
Keyword(s):  
Cell Wall ◽  
Vascular Tissue ◽  
Golgi Body ◽  
Cell Wall Polysaccharide ◽  
Polysaccharide Synthesis ◽  
Chemical Studies

Chemical and radioautographic studies on sycamore seedling stems have shown an involvement of the Golgi body in cell-wall polysaccharide synthesis from tritiated glucose. Tritiated phenylalanine is shown to be incorporated only into lignin after short incubation times. The patterns of labelling are compared and discussed for the two precursors.

Production of Monoclonal Antibodies Against the Outer Cell Wall ofClostridium tyrobutyricum

Hybridoma ◽  
1994 ◽  
Vol 13 (1) ◽  
pp. 45-51 ◽  
Author(s):  
FRANCOISE TALBOT ◽  
GEORGES ROBREAU ◽  
FRANCOISE GUEGUEN ◽  
ROGER MALCOSTE
Keyword(s):  
Cell Wall ◽  
Monoclonal Antibodies ◽  
Outer Cell ◽  
Outer Cell Wall
Sign in / Sign up

Export Citation Format

Share Document