Showing papers in "Protoplasma in 1983"
TL;DR: The embryogenic callus was formed by divisions in mesophyll cells situated primarily in the abaxial half of the leaf, and also from cells of the vascular parenchyma, and showed the typical organization of grass embryos.
Abstract: Embryogenic callus was induced on segments of young leaves of sugarcane (Saccharum officinarum L) cultured on Murashige and Skoog's medium supplemented with 05–30 mg/2,4-D, 5% coconut milk and 3–8% sucrose The fourth and fifth leaves, especially their midrib and sheath regions within 5 cm from the leaf base, were most suitable for the induction of embryogenic callus Many embryoids (= somatic embryos) were formed when the callus was transferred to low 2,4-D media (025–05 mg/l), or was allowed to remain on the high 2,4-D medium for a prolonged period Plantlets obtained from the germination of embryoids were transferred to soil and grown to maturity
237 citations
TL;DR: It is clearly demonstrated that tip extension is controlled, not only by the rate of vesicle fusion, but also by the state of plasticity of the tip; these processes appear to be sensitive to changes in Ca2+ ion concentration.
Abstract: Pollen tube growth is shown to be inhibited by both suboptimal ( 10−3 M) Ca2+ ion concentrations. Tip extension rates are independent of Ca2+ ion concentration over the optimal range. Changes in the structure of the tips of pollen tubes after transfer to inhibitory Ca2+ ion conditions provide evidence in support of our proposed mechanism of pollen tube tip growth (J. theor. Biol.98, 15–20, 1982). It is clearly demonstrated that tip extension is controlled, not only by the rate of vesicle fusion, but also by the state of plasticity of the tip; these processes appear to be sensitive to changes in Ca2+ ion concentration.
161 citations
TL;DR: Tissue cultures derived from the scutellum of immature embryos of Triticum aestivum L. (wheat) gave rise to somatic embryos with a well-defined scUTellum and coleoptile as well as one or more shoot primordia and a root primordium.
Abstract: Tissue cultures derived from the scutellum of immature embryos ofTriticum aestivum L. (wheat) gave rise to somatic embryos with a well-defined scutellum and coleoptile as well as one or more shoot primordia and a root primordium. The normal somatic embryos were formed from compact, white callus tissue which was not observed until 4 or more weeks after culture initiation. The highest frequency of white embryogenic tissue formation and the most normal embryoids were obtained in the dark on Murashige and Skoog's medium with twice the concentration of inorganic salts plus sucrose (2%), inositol (100–200 mg/l), casein hydrolysate (100–200 mg/l), glutamine (500 mg/l), and 2,4-dichlorophenoxyacetic acid (1–2 mg/l).
109 citations
TL;DR: Aequorin light emission transiently increased when the cell generated an action potential, which consisted of initial rapid depolarization and a subsequent maintenance of this at a plateau level and seemed to reflect the Ca2+ release from the plasmalemma.
Abstract: The photoprotein aequorin was introduced into tonoplast-freeChara cells. Aequorin light emission transiently increased when the cell generated an action potential, which consisted of initial rapid depolarization and a subsequent maintenance of this at a plateau level. The light emission change also consisted of two components. First was a rapid rise followed by a rapid return to nearly the initial level. This rapid component corresponded to the initial rapid depolarization of the action potential and seemed to reflect the Ca2+ release from the plasmalemma. The second component of light emission was a gradual increase of luminescence that continued for the prolonged depolarization phase of the action potential. When the action potential was terminated, the luminescence instantly began to decrease. This component probably reflects the Ca2+ influx through the plasmalemma which may become highly permeable to ions during excitation. Free Ca2+ concentrations of tonoplast-freeChara cells containing 1 m MEGTA are estimated to be about 2 μM at the resting state and about 4 μM at the initial phase of the light emission change.
89 citations
TL;DR: Cytoplasmic streaming in permeabilized Nitella cells was found to be controlled by Ca2+ of physiological concentration and was completely reversible even at 10−5 M.
Abstract: Cytoplasmic streaming in permeabilizedNitella cells was found to be controlled by Ca2+ of physiological concentration. The streaming driven by Mg · ATP was scarcely affected by 10−7 M Ca2+, but was inhibited significantly by 5 × 10−7 M Ca2+ and completely by 10−6 M Ca2+. The inhibition by Ca2+ was completely reversible even at 10−5 M.
87 citations
TL;DR: Embryoids which developed from callus obtained from leaves of Medicago sativa L. (alfalfa) were studied with the light and scanning electron microscopes and provided confirmation of the many stages of development and the very large number of embryoids present, as well as evidence of the range of form resulting from differential growth of regions of the embryos.
Abstract: Embryoids which developed from callus obtained from leaves ofMedicago sativa L. (alfalfa) were studied with the light and scanning electron microscopes; embryoids are not common in leguminous plants. Sections showed that in organised callus embryoids apparently originated from groups of embryonic cells, whereas in friable callus, and in the epidermis of cotyledons, hypocotyls and roots of callus-derived plantlets, they often originated from single cells. Many early stages of embryogenesis (1, 2, 3- and 4-celled stages) were observed, particularly in epidermal sites. Stages in somatic embryogenesis, though variable, resembled those described for the normal zygotic embryos of alfalfa. A suspensor-like structure was sometimes present in the embryoids. Numbers of cotyledons, up to six, were observed. The SEM provided confirmation of the many stages of development and the very large number of embryoids present, as well as evidence of the range of form resulting from differential growth of regions of the embryos.
80 citations
TL;DR: When grown in iron-free media, the youngest leaves of healthy green sugar beet plants became completely yellow after 6 to 8 days, but this chlorosis was quickly reversed by resupplying iron and the granal fretwork underwent further development.
Abstract: When grown in iron-free media, the youngest leaves of healthy green sugar beet plants became completely yellow after 6 to 8 days. This chlorosis was quickly reversed by resupplying iron. A study of the ultrastructure of the iron -stressed leaves revealed apparently normal subcellular organization except for the plastids which were small and undeveloped, contained a rudimentary, disorganized grana-fretwork and clusters of vesicles in the periphery. Twelve to 16 hours after resupply of iron, aggregates of phytoferritin were observed in the stroma, and the granal fretwork underwent further development. There was an increased orientation of the membranes along the long axis of the plastids and an increase in the length of the individual grana stacks. By 48 hours, leaf chlorophyll content was about 40% of the control. At the ultrastructural level, parallel alignment of membrane orientation was complete and the grana stacks began to increase in the number of thylakoids per stack.
73 citations
TL;DR: The aim of the present study was to determine the localization of polysaccharides in both C and N cells electron microscopically and suggested that the divergent morphology of the “calcifying” system of N cells accounts for its failure to produce coccoliths.
Abstract: Emiliania huxleyi is a marine coccolithophorid which produces coccoliths,i.e., particles consisting of calcite and macromolecular organic material. The coccoliths are formed intracellulary in specialized organelles which comprise a coccolith vesicle (CV) and a reticular body (RB), together forming the CV/RB system or calcifying system. After termination of calcification, the coccolith is extruded and incorporated into the coccosphere,i.e., one or several layers of extracellular coccoliths surrounding the cell. Apart from the coccolith-producing cells (C cells) ofE. huxleyi, there are naked cells (N cells) which seem to have lost the capacity to produce coccoliths but are very similar to the C cells in other morphological respects. Biochemical studies have revealed that polysaccharides may play a regulatory role in calcification. The aim of the present study was to determine the localization of polysaccharides in both C and N cells electron microscopically. For this purpose, a cytochemical staining technique according toThiery (1967) was applied. The CV/RB system of C cells was conspicuously stained. Due to the excellent stainability of this system, a putative succession of morphological stages during coccolithogenesis could be described. The staining pattern of the N cells closely resembled that of the C cells. It was found, however, that the “calcifying” system of N and C cells differed in both morphology and position. It is suggested that the divergent morphology of the “calcifying” system of N cells accounts for its failure to produce coccoliths.
72 citations
TL;DR: The cell wall of root hairs of Equisetum hyemale is shown to be composed of three different cell wall textures, indicating that longitudinally oriented layers prevail over layers with a transverse direction.
Abstract: The cell wall of root hairs ofEquisetum hyemale is shown to be composed of three different cell wall textures. The growing cell wall at the tip of the hair is composed of a dispersed texture of microfibrils, which continues along the outside of the whole hair. With increasing distance from the tip an increasing number of helicoidally arranged lamellae is deposited. These findings correspond with the observed isotropism of young hairs in polarized light. Hairs of approximately 4 days old become positive birefringent, indicating that longitudinally oriented layers prevail over layers with a transverse direction. This phenomenon starts at the base of the hair. Full-grown hairs are positive birefringent up to the tip and concordantly show a thick additional inner cell wall layer which forms a helical pattern the length of the hair, with a mean microfibril angle of 25∘ with the cell axis. Cortical microtubules, subjacent to the dispersed, the helicoidal and the helical wall texture are axially aligned and, thus, not in coalignment with the last deposited microfibrils. Coated and smooth vesicles are present in the cortical cytoplasm of both growing and full-grown hairs. Electron-dense profiles (20 nm in diameter), surrounded by a halo (of 50 nm) were observed on the wall-plasmalemma interface in full-grown hairs only. A relation of these structures with microfibril deposition could not be demonstrated. They might represent channels transporting material to the wall, which, in full-grown hairs, is heavily impregnated with a tawny brown substance. The general hypothesis that cortical microtubule orientation directs microfibril deposition is disputed.
72 citations
TL;DR: In this paper, the intracellular calcium distribution in pollen tubes ofLilium longiflorum was measured by proton-induced X-ray emission (PIXE) with the Heidelberg proton microprobe, which is a new method for biological application.
Abstract: The intracellular calcium distribution in pollen tubes ofLilium longiflorum was measured by proton-induced X-ray emission (PIXE) with the Heidelberg proton microprobe, which is a new method for biological application. Studies by electron-induced X-ray emission (EIXE) were done in comparison. Independent of the preparation technique, the pollen tubes show a tip-to-base calcium gradient. The shape of the calcium gradient and the total calcium content depend on the preparation technique. The calcium ionophore A-23187 destroys the calcium gradient and leads to a loss of most cell calcium. Chlorotetracycline (CTC) treatment increases the amount of membrane-bound calcium.
71 citations
TL;DR: Experimental evidence is given for the assumption that these secondary components are located on the pollen wall and/or in its cavities, and that flavonoids are loosely associated with the pollen, and in contrast to vacuole-accumulated flavonoid, can be very easily removed from the grains.
Abstract: 1.
Pollen grains accumulate many secondary plant products, especially flavonoids and carotenoids. Quantitative analysis have revealed that up to 2–4% of pollen dry weight consist of accumulated flavonols. For pollen ofCorylus avellana, a flavonol content of 0.286 ng per pollen grain could be measured.
2.
Short-time extraction experiments and pollen prints demonstrated that flavonoids are loosely associated with the pollen, and in contrast to vacuole-accumulated flavonoids, can be very easily removed from the grains. Experimental evidence is given for the assumption that these secondary components are located on the pollen wall and/or in its cavities.
TL;DR: The overall morphology of the developing wheat embryo in relation to its neighbouring tissues is described and the accumulation of starch and protein appears to begin first in the basal tissues of the scutellum and coleorhiza.
Abstract: The overall morphology of the developing wheat embryo in relation to its neighbouring tissues is described. The embryo is “isolated” early in development, but appears to be a powerful sink for nutrients. It is supplied initially by hydrolysis of the nucellar parenchyma and later by hydrolysis of neighbouring endosperm cells, which are completely digested. Later on, the nucellar epidermis forms specialised cells that may be transfer cells opposite the groove at the base of the embryo. The accumulation of starch and protein appears to begin first in the basal tissues of the scutellum and coleorhiza.
TL;DR: The first steps to successful microinjection in plant cells of different types of macromolecules (RNA, DNA and protein) are reported and evidence is given that plant cells can survive the mechanical injury of the injection procedure.
Abstract: The first steps to successful microinjection in plant cells of different types of macromolecules (RNA, DNA and protein) are reported. Evidence is also given that plant cells can survive the mechanical injury of the injection procedure. By attaching the cells to coverslips with polylysine, the progeny of an individual cell can be followed microscopically. Using the fluorescent dye Lucifer Yellow, the injection procedure can be monitored and the injected volume calculated.
TL;DR: This description of tapetal ultrastructure starts from the meiotic prophase when the tapetum is still cellular and comprises two rows of cells on the inside of the tetrasporangiate anther.
Abstract: A tapetum is found around all higher plant meiocytes and is thought to nourish them. It may, in turn, be influenced by their development. The mature tapetal membrane in amoeboid (or periplasmodial) tapeta, of whichArum italicum is an example, fits closely around the developing meiocyte.
TL;DR: The present model is superior to the previous detergent model in which the streaming lasted shorter time and was inhibited irreversibly by cytochalasin B (Shimmen andTazawa 1982a).
Abstract: A method to permeabilize theNitella cell without using detergent was developed. The cell was pretreated with an EGTA-containing medium and subsequently plasmolysed at low temperature. The streaming which had been stopped in a medium containing no ATP could be reactivated by the Mg · ATP-containing medium and continued for more than one hour. The rate of the reactivated streaming for the first 30 minutes was almost the same as that of the normal streaming. The reactivated streaming was inhibited irreversibly by Mg2+ depletion and reversibly by cytochalasin B. Thus, the present model is superior to the previous detergent model in which the streaming lasted shorter time and was inhibited irreversibly by cytochalasin B (Shimmen andTazawa 1982a).
TL;DR: It was found that an increased amount of KNO3 did not raise the rate of embryoid formation, and embryoids most likely originated from single cells which, however, may be part of a larger proembryonal cell complex.
Abstract: The development of embryoids on punched leaf expiants fromCoffea canephora was studied. Both culture conditions as well as structural changes were investigated. The expiants were placed on a modified Murashige and Skoog medium with different concentrations of KNO3. It was found that an increased amount of KNO3 did not raise the rate of embryoid formation.
TL;DR: Zoospores of Friedmannia are structurally most similar to those of the Chaetophoralean green algaMicrothamnion and it is concluded that these two genera form a natural group and taxonomic implications are discussed.
Abstract: Zoospore ultrastructure in the green algaFriedmannia israelensis has been studied in detail using serial section and absolute configuration analysis The zoospores are naked, biflagellate and considerably flattened In addition they exhibit an asymmetric external shape and an asymmetric distribution of major cell organelles There is only a single contractile vacuole/cell 3-dimensional reconstructions of mitochondrial profiles show the presence of a single branched mitochondrial reticulum/cell The nucleus is pear-shaped and exhibits an anterior projection In a concave depression of this projection lies the single dictyosome of the zoospore The nuclear envelope presumably buds off small vesicles at the forming face of the dictyosome The single chloroplast lacks an eyespot and pyrenoid A single microbody is characteristically located posterior to the nucleus in close association with an elongated mitochondrial profile The zoospores contain a peculiar system of three major ER-cisternae, of which an anterior one is linked to a mitochondrial profile The flagellar apparatus has been studied in detail and its absolute configuration has been determined The two basal bodies are displaced (in the 11/5 o'clock direction) and overlap at their proximal ends They are interconnected by a principal non-striated capping plate and two smaller striated connecting fibres The flagellar root system consists of a cruciate microtubular root system (4-2-4-2 or 5-2-5-2 system) and a greatly reduced system II fibre which connects one basal body with the nuclear membrane and runs along a smooth ER-cisterna The 4- or 5-stranded roots are proximally associated with a terminal cap-like structure which consists of a number of parallel striations spaced 13 nm Zoospores ofFriedmannia are structurally most similar to those of the Chaetophoralean green algaMicrothamnion It is concluded that these two genera form a natural group and taxonomic implications are discussed The absolute configuration analysis of the flagellar apparatus indicates thatFriedmannia has an Ulvaphycean-type flagellar apparatus Phylogenetic aspects of the absolute configuration of the flagellar apparatus in green algae are discussed
TL;DR: The connections and structural inter-relations of dictyosomes and endoplasmic reticulum (ER) in cotyledons of germinating mung beans were studied using thick sections of aldehyde fixed, zinc iodide-osmium tetroxide (ZIO) impregnated tissue.
Abstract: The connections and structural inter-relations of dictyosomes and endoplasmic reticulum (ER) in cotyledons of germinating mung beans were studied using thick (03 μm) sections of aldehyde fixed, zinc iodide-osmium tetroxide (ZIO) impregnated tissue The sections were examined by conventional (100 kV), rather than high voltage, transmission electron microscopy Continuity of cisternal ER with tubular ER was confirmed and a direct connection of tubular ER totrans dictyosome cisternae was observed as were GERL networks associated withtrans dictyosome cisternae Dictyosomes also gave rise to an extensive system of very fine tubules (10–20 nm diam) which have not been described previously in plant tissue These tubules, which originated at thetrans dictyosome face, extended throughout the cytoplasm and were found connected to cisternal ER and tubular ER The implications of these observations are discussed with regard to present ideas concerning endomembrane flow and protein sorting by the Golgi apparatus
TL;DR: The observations favour the hypothesis that prominent microtubule organizing centres (MTOCs) function in the cortical cytoplasm of the midregion of the periclinal walls surrounding the ventral one for a relatively long time.
Abstract: The cortical cytoplasm of the young guard cells ofAdiantum capillus veneris is locally differentiated. At an early post-telophase stage, numerous microtubules diverge from the cytoplasm occupying the junctions of the midregion of the ventral wall with the periclinal ones, towards the periclinal and ventral wall faces as well as towards the inner cytoplasm. Microtubule-vesicle complexes (MVCs) are detected in these regions. Their appearance is accompanied by the initiation of local wall thickenings in the same areas.
TL;DR: The raphes of a moving diatom are filled with mucilage strands which are perpendicular to the slit and protrude from the external raphe fissure, and the distal ends of the strands are capable of adhering to the substratum.
Abstract: The raphes of a moving diatom are filled with mucilage strands which are perpendicular to the slit and protrude from the external raphe fissure. The distal ends of the strands are capable of adhering to the substratum.Navicula cuspidata moves with only the posterior half of the cell adhered; the anterior is elevated from the substratum. The species studied left no apparent mucilage trails.
TL;DR: In the giant cells the cytoplasm was frequently filled with an extraordinary accumulation of paramylum grains or almost totally replaced by enormous vacuoles and the cell and nuclear membranes became more permeable to vital stains.
Abstract: Synchronous cultures ofEuglena gracilis Klebs were grown axenically in continuous light for six days in the presence or absence of 1.5, 3.0, 4.5, 7.5, 9.0 μg/ml of Cr6+ supplied as K2Cr2O7. In the presence of chromium, cell proliferation was drastically inhibited and many giant organisms containing multiple nuclei frequently appeared. Chlorophyll content and photosynthetic activity diminished greatly. Accordingly, plastids, which increased abnormally in number in giant cells, showed a weak fluorescence and a reduced internal organization. Mitochondria were generally enlarged and variously branched while respiration rate fell. Nuclei were very large and frequently exhibited the ultrastructural characteristics of those in G2 phase of the cell cycle. The cell and nuclear membranes became more permeable to vital stains. In the giant cells the cytoplasm was frequently filled with an extraordinary accumulation of paramylum grains or almost totally replaced by enormous vacuoles. The observed alterations may be related to the formation of Cr-complexes with a variety of biological ligands, primarily nucleic acids, proteins and free SH groups.
TL;DR: Postmitotic nuclear migration and anchoring inMicrasterias seems to be mediated by two distinct microtubule (MT)-systems: the moving MT-system, called “posttelophase system of MT” (PTS) which arises from a node-like structure and the anchoring MT- system, called“isthmus system ofMT’ (IS) which surrounds the nucleus at its central position.
Abstract: Postmitotic nuclear migration and anchoring inMicrasterias seems to be mediated by two distinct microtubule (MT)-systems: the moving MT-system, called “posttelophase system of MT” (PTS) which arises from a node-like structure, possibly a microtubulecenter (MC) and the anchoring MT-system, called “isthmus system of MT” (IS) which surrounds the nucleus at its central position. The nucleus or parts of its envelope seems to be involved in the nucleation and orientation of these MT-systems. The moving force of the nuclear migration process obviously originates from interaction between the MT-system (PTS) and its adjacent microfilaments.
TL;DR: The effects of UV-B and UV-C radiation were different, suggesting different mechanisms of action, discernible even at the ultrastructural level, and several structural changes were seen in theUV-B treated material.
Abstract: The effect of UV-C (254 nm) and UV-B (290–320 nm) radiation on leaves ofBeta vulgaris L. at the ultrastructural level was investigated. Although the damage caused by UV-C radiation was more striking than that resulting from UV-B radiation, several structural changes were seen in the UV-B treated material. Generally the effects of UV-B and UV-C radiation were different, suggesting different mechanisms of action, discernible even at the ultrastructural level.
TL;DR: Investigations on the subcellular localization of the two steroidal saponins avenacoside A and B of oat by fractionation of leaf homogenates indicate that these saponin are located in the soluble cell fraction of etiolated as well as green leaves.
Abstract: Investigations on the subcellular localization of the two steroidal saponins avenacoside A and B of oat by fractionation of leaf homogenates indicate that these saponins are located in the soluble cell fraction of etiolated as well as green leaves. The analysis of isolated green mesophyll protoplasts reveals that the mesophyll of green oat leaves contains only 50% of the leaf saponins. This reduction is nearly exclusively caused by a reduction of avenacoside B in mesophyll protoplasts in contrast to the epidermis which shows high concentrations of avenacoside B and only traces of avenacoside A. Investigations of isolated vacuoles in comparison to isolated mesophyll protoplasts showed that the steroidal saponins are predominantely localized in the vacuole. Furthermore, results are presented which indicate that the avenacosides A and B may be used as markers for the integrity of isolated protoplasts and vacuoles.
TL;DR: The organization and absolute configuration of the entire flagellar apparatus of theColeochaete pulvinata zoospore is compared to swarmers of other green algae belonging to theCharophyceae sensu Stewart and Mattox and to bryophyte spermatids.
Abstract: A detailed description of the zoospore and its flagellar apparatus (including their absolute configuration) of the filamentous, branched green algaColeochaete pulvinata is given. It shares several features with the previously studied swarmers ofColeochaete scutata, such as the presence of a multi-layered structure (MLS) — associated microtubular root, and diamond-type body and flagellar scales. New observations include a T-shaped striated fiber linking the two basal bodies to the MLS, four additional fibrous connections between individual basal bodies and the MLS, and a second rootlet consisting of three microtubules. The organization and absolute configuration of the entire flagellar apparatus of theColeochaete pulvinata zoospore is compared to swarmers of other green algae belonging to theCharophyceae sensu Stewart and Mattox and to bryophyte spermatids. Some new aspects of their phylogenetic relationships are discussed.
TL;DR: There is a maximum concentration of membrane-associated calcium consistent with normal pollen germination and tube growth and that phenothiazines interfere with the unloading of Ca2+ from membrane sites.
Abstract: Pear (Pyrus communis L.) pollen was germinated and grown in hanging drop cultures containing phenothiazine drugs, trifluoperazine and chlorpromazine, potent inhibitors of the Ca2+-calmodulin complex. Responses for the two drugs were similar: at 1.0–2 10.0 ΜM pollen germination and tube growth were inhibited. Inhibition of tube growth was not uniform; at 10.0 ΜM growth of about half of those tubes which had germinated was inhibited while the remaining half of the population grew normally. This bimodal distribution of tube growth was noted, but to a lesser extent, at lower concentrations of the drugs as well. Microfluorometric analysis of membrane calcium using chlorotetracycline, a fluorescent chelate probe for membrane calcium, revealed that upon pollen grain hydration there was a sharp decrease in the concentration of calcium associated with membranes and that membrane calcium became localized primarily at the periphery of the newly hydrated pollen grain. Prior to germination there was a reloading of calcium onto membranes in the region of the germination aperture through which the pollen tube would emerge. The release of Ca2+ from membrane sites upon hydration was partially inhibited by treatment with 10 ΜM trifluoperazine. Distribution of membrane calcium in populations of the inhibitor-treated pollen grains was not bimodal however; approximately half of the population had CTC-fluorescence emissions exceeding the maximum value found in the control population. These results suggest that there is a maximum concentration of membrane-associated calcium consistent with normal pollen germination and tube growth and that phenothiazines interfere with the unloading of Ca2+ from membrane sites.
TL;DR: Chemical analysis of the isolated fibre cell walls confirmed the presence of suberin, the dominant monomer being 22-hydroxydocosanoic acid (65% of the total monomeric mixture), which strongly suggest that subers, as well as waxes, are associated with the formation of the concentric rings of lamellated lipid material which characterise the walls of green lint cotton fibres.
Abstract: The secondary cell walls of fibres of the green lint variety of cotton are strongly autofluorescent and stain with both Sudan III and osmium tetroxide. In the electron microscope thin sections of aldehydeosmium fixed fibres show concentric, osmiophilic layers in the walls, each separated by cellulosic material. The number of these layers corresponds approximately to the number of days of secondary wall formation suggesting a periodic deposition. At higher magnifications each osmiophilic layer consists of several alternating electron opaque and electron translucent lamellae with a periodicity of about 4.2 nm. Ovules of the same variety culturedin vitro, in the dark and at constant temperature, also develop green fibres exhibiting the same ultrastructural features. Chemical analysis of the isolated fibre cell walls confirmed the presence of suberin, the dominant monomer being 22-hydroxydocosanoic acid (65% of the total monomeric mixture). These findings strongly suggest that suberin, as well as waxes, are associated with the formation of the concentric rings of lamellated lipid material which characterise the walls of green lint cotton fibres. A similar polymeric lipid also occurs in green lint epidermal cells that do not form fibres. However, in the white lint variety this polymer is restricted to the outer part of non-fibre forming epidermal cells and to the lateral walls at the base of the fibres.
TL;DR: The successful culture of isolated protoplasts of tobacco in the presence of a vital fluorescence stain, Calcofluor White (CW), is reported, indicating that a rigid cell wall is not a prerequisite for cell division.
Abstract: The successful culture of isolated protoplasts of tobacco in the presence of a vital fluorescence stain, Calcofluor White (CW), is reported. The method can be used in both liquid culture and with cells immobilized in agar. Wall formation seems to start at distinct points and can be observed as early as one hour after protoplast isolation. The material either spreads from these points over the entire surface, or the synthesizing apparatus moves in a manner which allows the formation of a continuous layer. The crystallization of the newly synthesized material seems to be hindered by CW, indicating that a rigid cell wall is not a prerequisite for cell division. On the other hand, no cytokinesis occurred unless the protoplasts were surrounded by material showing CW-fluorescence.
TL;DR: Chitin microfibrils exposed by chemical extraction of hyphal walls of Candida albicans, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidiodes brasiliensis, Coprinus cinereus andMucor mucedo were of variable morphology but gave identical infrared spectra and behaved as pure chitin in chromatographic analyses.
Abstract: Chitin microfibrils exposed by chemical extraction of hyphal walls ofCandida albicans, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidiodes brasiliensis, Coprinus cinereus andMucor mucedo were of variable morphology but gave identical infrared spectra and behaved as pure chitin in chromatographic analyses The microfibrils of the four dimorphic fungi studied were shorter than those in the mouldsC cinereus andM mucedo but were similar to those reported for the yeastSaccharomyces cerevisiae InC albicans the microfibrils in the septal plates of hyphae were predominantly tangentially orientated and were longer than those in the lateral walls Microfibrils produced by chitin synthasein vitro were very much longer than any observed from hyphal preparations
TL;DR: Protoplasts isolated from leaf material of several cabbage cultivars have been induced to divide in culture to produce callus and undergo shoot and root morphogenesis at a reproducible frequency.
Abstract: Protoplasts isolated from leaf material of several cabbage cultivars have been induced to divide in culture to produce callus Calli transferred to regeneration medium undergo shoot and root morphogenesis at a reproducible frequency Plants have been successfully established in soil and placed in glasshouse conditions