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Treponema denticola, a helically shaped motile microorganism, is a major pathogen of chronic periodontitis. Major surface protein (Msp) and dentilisin are virulence factors of T. denticola that are located on the outer sheath. The motility of T. denticola is deeply involved in colonization on and invasion into the host tissue. The outer sheath is located at the interface between the environment and T. denticola, and its components may also contribute to its motility via interaction to the materials outside of the cells. We aimed to clarify whether Msp or dentilisin contributes to the motility of T. denticola on solid surfaces, termed as crawling, by investigating their effects using Msp-deficient and dentilisin-deficient T. denticola strains. Motility was analyzed by measuring the colony size in agar plates and velocity was analyzed using dark-field microscopy. The colony area of the mutant strains was smaller than that of the wild-type strain. The crawling velocity of the mutant strains was lower than that of the wild-type strain, with the lowest velocity observed in the dentilisin-deficient strain. Additionally, the ratio of the crawling distance by one revolution to the protoplasmic cylinder pitch (an indicator of the crawling efficiency) in the dentilisin mutant was significantly lower than that in the wild type strain and the Msp mutant. Altogether, these results indicated that dentilisin facilitates the crawling-dependent surface spreading of T. denticola. This article is protected by copyright. All rights reserved.

SUMMARY The detailed segregative cell division (SCD) processes and changes in the arrangement of cortical microtubules and actin filaments were examined in two species of S truvea. SCD was initiated by the appearance of annular constrictions along the lateral side of a mother cell. The constrictions decreased in diameter, became thin, tubular in shape, and pinched the protoplasm of the mother cell into several protoplasmic sections. The protoplasmic sections expanded and developed into daughter cells, which appressed each other, and were arranged in a single row. Lateral branches protruded from the upper parts of the daughter cells. The protoplasm of the lateral branches was divided by secondary SCDs and was distributed amongst the new daughter cells. SCD and lateral branch formation were essential for morphogenesis in S truvea. Cortical microtubules were arranged parallel and longitudinally to the cell axis before SCD. When SCD was initiated, there was considerable undulation of the cortical microtubules and several transverse bundles appeared in the cytoplasmic zone where annular constrictions occurred. A microtubule-disrupting drug (amiprophos methyl) inhibited SCD. Actin filaments maintained reticulate patterns before and during SCD. These results demonstrated that SCD in Struvea species was quite distinct from that in D ictyosphaeria cavernosa reported previously.

Explanations for protoplasmic streaming began with appeals to contraction in the eighteenth century and ended with appeals to contraction in the twentieth. During the intervening years, biologists proposed a diverse array of mechanisms for streaming motions. This paper focuses on the re-emergence of contraction among the molecular mechanisms proposed for protoplasmic streaming during the twentieth century. The revival of contraction is a result of a broader transition from colloidal chemistry to a macromolecular approach to the chemistry of proteins, the recognition of the phenomena of shuttle streaming and the pulse of protoplasm, and the influential analogy between protoplasmic streaming and muscle contraction. Michael R. Dietrich

BACKGROUND: In this study we examined the influence of various forms of selenium (organic and inorganic) on the vivacity of Hericium erinaceum mycelium and structural changes and ultrastructure occurring during its development in submerged culture. RESULTS: The mycelium was grown on sodium selenite (Na2SeO3), Selol (with 20 and 50 g kg −1 Se, respectively) and a mixture of Na2SeO3 and Selol. Samples of the mycelium were collected on day 3 and day 24 of the incubation and viewed under an electron microscope. Selol at concentration 20 g kg −1 did not cause any damage to the cell ultrastructure, but it contributed to the thickening of the cell wall, which implied an influence on polysaccharide production. In the other cases, degradation changes appeared in the protoplasm and the thickness of the cell wall did not increase. CONCLUSION: The nature of the effect exerted by various sources of selenium in the culture medium on the formation of polysaccharides probably results from the differences in their chemical composition and differences in the toxicity of these compounds towards the cells, but is also connected with the decomposition of the wall surrounding degraded fungal cells. © 2014 Society of Chemical Industry

Bench-scale experiments were conducted to evaluate effects of UV radiation (UVR) on Limnoithona sinensis (Copepoda, Crustacea). Results showed that water depth, wavelength, and irradiation time significantly reduced the swimming activity of L. sinensis. The inactivation rate increased with irradiation time, and there was an inverse relation between inactivation rate and water depth. Positive phototaxis was observed in copepods exposed to visible light with wavelengths of 480 or 500 nm, which caused a substantial increase in the inactivation rate when UVR was combined with visible light. Scanning electron microscopy showed that the skin of L. sinensis inactivated by UVR appeared dry and wrinkled, which was possibly due to induction of osmotic changes across cell membranes. As indicated by three-dimensional fluorescence spectra showing leakage of protoplasm to the external environment.

SUMMARY Female gametogenesis was studied in the dioecious siphonous green alga Codium fragile subsp. novae-zelandiae (J. Agardh) P. C. Silva using light and electron microscopy. Early during gametogenesis the protoplasm was uniform; then it separated in portions, while fusiform chloroplasts and nuclei increased in numbers. Some features of the nuclear divisions were similar to those of other Bryopsidophyceae. They were acentric and semi-open. Pairs of parallel electron-dense lines resembling synaptonemic complexes were observed in several prophase nuclei indicating meioses. In metaphase the nuclear envelope showed polar fenestrae from which the spindle emerged. No spindle microtubule nucleating material was visible and chromosome kinetochores were evident. Mature female gametes were pyriform with a hyaline anterior end from which the two flagella emerged. Mature gametes had a spherical nucleus surrounded by a mitochondrion and numerous discoid chloroplasts. Female gametes germinated parthenogenetically in culture and also inside gametangia, involving loss of flagella, rounding and lengthening of cells, multiplication of chloroplasts with well developed thylakoid systems, vacuolization and synthesis of a fibrillar cell wall.

The Doppler optical coherence tomography technique was applied to image the oscillatory dynamics of protoplasm in the strands of the plasmodium of slime mould Physarum polycephalum. Radial contractions of the gel-like walls of the strands and the velocity distributions in the sol-like endoplasm streaming along the plasmodial strands are imaged. The motility inhibitor effect of carbon dioxide on the cytoplasm shuttle flow and strand-wall contraction is shown. The optical attenuation coefficient of cytoplasm is estimated. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Summary This work was undertaken to find out, using plant physiological methods, the reaction of plant tissue to the penetration by and feeding of plant lice; it showed that spontaneous primary reactions and long term secondary reactions must be distinguished. Shock like disturbances in the transpiration and water intake of the host plant and interference with photosynthesis (by lowering of the assimilation rate) and respiration were established as primary reactions. In the vicinity of the puncture, a raising of the permeability, alteration in viscosity and the raising of the rate of flow of protoplasm could be proved cytophysiologically. The importance of these cytophysiological effects on the feeding of the plant lice is discussed. Besides the already known secondary reactions such as inhibition of growth, gall formation, shoot deformation etc., restriction of flowering and shooting and alterations in osmotic value (alterations in enzyme activity) are described, as well as long term respiration increases, e. g. attack by Quadraspidiotus perniciosus Comst. raises the oxygen consumption to three times its normal value. As it was thought that, besides the mechanical effects, the saliva of plant lice was mainly responsible for phytopathological symptoms, analyses of pure saliva were carried out to determine the enzymes and free amino acids. The free amino acids found had an effect on the respiration, photosynthesis and water balance of the plant tissues and must therefore be largely concerned in the phytopathological effects. The mechanism of saliva secretion was found by the use of a tracer (P32). In phloem feeding aphids (Myzus ascalonicus Donc.), saliva is secreted only with insertion (6–8 min. long) and retraction of the stylets and not in the intervening time no matter how long the insect may feed. In contrast to this, parenchyma feeders secrete more or less continuously and the fundamental differences between the two types of feeding are fully discussed. The mutual effects on plant and aphid, with a parenchyma feeding species, are well illustrated by histochemical and physiological methods, using as an example the bark of Abies pectinata attacked by Adelges piceae. The spread of saliva in the plant is described in detail, using autoradiographic and X-ray techniques. The mechanism of feeding in Myzus ascalonicus is calculated in relation to the relevant pressure conditions and rates of flow.

Summary: Candida albicans was grown on agar plates on which paper discs impregnated with natamycin were applied to demonstrate the antimycotic effect of the drug. Small agar blocks were taken for electron microscopy from the margin of the inhibitory zone, from areas of uninhibited growth as well as from the inhibitory zone close to the application of paper discs. The morphology of Candida cells outside the inhibitory zone was normal and well preserved. Only a few deformed cells surrounded by cytoplasmic structures were found in the inhibitory zone. The cells at the margin of the inhibitory zone were increased in size, the internal structure was largely destructed and the cell wall was thin and uneven in thickness. There were definite holes in the cell wall through which protoplasm was seen discharging from the cell. And plenty of material resembling protoplasm was found in the agar surrounding the cells. A part of the holes were interpreted as consequencies of unsuccessful bud formation. Zusammenfassung: Candida albicans wurde auf festen Nahrboden in Petrischalen angezuchtet. Der Nahrboden war mit Papierscheiben bedeckt, die mit Natamycin impragniert waren, um die antimykotische Wirkung des Medikamentes zu demon-strieren. Kleine Agarblockchen wurden fur die elektronenmikroskopische Unter-suchung vom Rande der Hemmzone, von Gebieten mit ungehemmtem Wachstum und von der Hemmzone selbst aus der Nahe der Papierscheiben entnommen. Die Morphologie der Candidazellen auserhalb der Hemmzone war normal und unbeein-trachtigt. In der Hemmzone selbst wurden nur wenige deformierte Zellen gefunden, die von zytoplasmatischen Strukturen umgeben waren. Die Zellen vom Rande der Hemmzone waren vergrosert, die inneren Strukturen waren weitgehend zerstort und die Zellwand war dunn und zeigte ungleichmasige Dicke. In der Zellwand waren eindeutig Locher festzustellen, durch die sich das Protoplasma aus dem Zellinneren nach ausen entleert. In der Umgebung der Zellen wurde in dem Agar reichlich Material gefunden, das wie Protoplasma aussah. Ein Teil der Locher wurde als Folge einer frustranen Sproszellformation angesehen.

Summary Through electron microscopic observations of the normal mouse spleen, the following findings were obtained concerning denucleation mechanism of the erythroblast: 1. In mice the nuclei of the erythroblasts are denucleated by phagocytic activity of the reticular cell, located in the center of the erythroblastic islets. In a physiologic state, this mechanism is considered to be playing the main role in denucleation. 2. The protoplasmic projection of the reticular cell compresses and makes an infolding between the head and body of the orthochromatic erythroblast, and finally the head is cut off and phagocytized by this reticular cell, leaving the body to develop into a reticulocyte.

We investigated the role of the “sieve tube-companion cell complex” lining the tube periphery, particularly the microfilament and microtubule, in assisting the pushing of phloem sap flow. We made a simple phloem transport system with a living radish plant, in which the conducting channel was exposed for local treatment with chemicals that are effective in modulating protoplasmic movement (acetylcholine, (ACh) a neurotransmitter in animals and insects; cytochalasin B, (CB) a specific inhibitor of many cellular responses that are mediated by microfilament systems and amiprophos-methyl, (APM) a specific inhibitor of many cellular responses that are mediated by microtubule systems). Their effects on phloem transport were estimated by two experimental devices: (i) a comparison of changes in the amount of assimilates in terms of carbohydrates and 14C-labeled photosynthetic production that is left in the leaf blade of treated plants; and (ii) distribution patterns of 14C-labeled leaf assimilates in the phloem transport system. The results indicate that CB and APM markedly inhibited the transfer of photosynthetic product from leaf to root via the leaf vein, while ACh enhanced the transfer of photosynthetic product in low concentrations (5.0×10-4 mol/L) but inhibited it in higher concentrations (2.0×10-3 mol/L) from leaf to root via the leaf vein. Autoradiograph imaging clearly reveals that ACh treatment is more effective than the control, and both CB and APM treatments effectively inhibit the passage of radioactive assimilates. All of the results support the postulation that the peripheral protoplasm in the sieve tube serves not only as a passive semi-permeable membrane, but is also directly involved in phloem transport.

In many environments, leaves experience large diurnal variations in temperature. Such short-term changes in temperature are likely to have important implications for respiratory metabolism in leave ...

SUMMARY 1. The proportion of metabolically active mass in the freshwater amphipod Gammarus fossarum was determined using different parameters [chemical oxygen demand (COD), total nitrogen (Ntot), total phosphorus (Ptot) and mass of chitinous cuticle]. 2. The results of linear regressions between body mass and body length, and measured parameters (COD, Ntot, Ptot) show high correlation coefficients for both fresh and the dry animals. The proportion of chitinous mass increased with body size. 3. Chemical analysis of Ptot in individuals appears to be the most appropriate parameter for quantitating the metabolically active tissues in animals. 4. The dependence of the intensity of electron transport system (ETS) activity per protoplasm, calculated from the Ptot and dry mass of animals, shows that large animals have the same ETS activity per unit of protoplasm as smaller ones. 5. We conclude that the chitinous mass is not the only factor which contributes to negative allometry of metabolic activity in G. fossarum.

Protoplast regeneration from extruded cytoplasm of the multicellular marine green alga Microdictyon umbilicatum (Velley) Zanardini (Cladophorales, Anadyomenaceae) was investigated. The early process of protoplast formation is comprised of two steps: agglutination of cell organelles into protoplasmic masses followed by generation of a temporary enclosing envelope around them. Agglutination of cell organelles was mediated by a lectin‐carbohydrate complementary system. Three sugars, D-galactosamine, D-glucosamine, and � -D-mannose, inhibited the agglutination process, and three complementary lectins for the above sugars, peanut agglutinin, Ricinus communis agglutinin, and concanavalin A, bound to the surfaces of chloroplasts. Agglutination assay using human erythrocytes showed the presence of lectins specific for the above sugars in the algal vacuolar sap. A fluorescent probe 1-(4-trimethylammoniumphenyl)-6-phenyl-a, 3,5-hexatriene revealed that the envelope initially surrounding protoplasts was not a lipid-based cell membrane. However, this developed several hours later. Simultaneous fluorescein diacetate and propidium iodide staining showed that the primary envelope had some characteristics of cell membranes, such as semipermeability and selective transport of materials. Also, fluorescein diacetate staining showed esterase activity in the protoplast and relocation of cell organelles and compartmentalization of cytoplasm during the process of regeneration. Both pH 7‐9 and salinity 400‐500 mM were found to be essentially important for the development of the protoplast envelope. When the basic regeneration process was accomplished, two alternative pathways of development were seen; about 70% of one-celled protoplasts transformed into reproductive cells within 2 weeks after wounding, whereas others began cell division and grew into typical Microdictyon thalli. Quadriflagellate swarmers were liberated from the reproductive cells, and they germinated into mature individuals. It is therefore suggested that this species may use the wound response as a method of propagation and dispersal.

Although egg cells are visible to the naked eye, the history of cell biology is closely coupled to that of microscopy. In nearly 350 years, cell research has produced an extraordinary rich panorama of studies, concepts and representations. Robert Hooke's 1665 analogy to monk cells, the transition from ‘cellular tissue’ to single ‘cells’ around the year 1800, Schleiden and Schwann's identification of the cell as the elementary unit of life, the prominent status it gained during cytology's expansion to the other fields of biomedical inquiry, Schultze's definition as ‘a clump of protoplasm containing a nucleus’, the worlds of endocellular and ultrastructural organization, the ‘compartimentalization’ of the cell in the 1950s and 1960s, its role as map for biochemical and molecular research, all these are just few of the many historical answers to the question ‘what is a cell and what is it good for?’. Key concepts: For the beginning of cell biology as a new research field it was not sufficient to be merely able to see cells. The development of cell biology was coupled with the evolution of optical instruments and of anatomical theory. One indispensable prerequisite for the formulation of the first cell theory was the shift from the concept of cellular tissue to that of cells as single units. Cell research underwent ‘golden ages’ whenever cells were considered the basic units of life. Many outstanding life scientists did not attribute central importance to cells. The study of cells was (and still is) extraordinarily rich in different ways of seeing, describing, depicting and conceiving. Though it originated from a specific theory, the history of cell biology is characterized by its growing independence from general theory. Throughout its history cell biology was characterized by its ability to expand into neighbouring research fields and to integrate their concepts and methods. Keywords: cell biology; cytoplasm; organelles; cell membrane; cell division; microscopy

Membrane remodeling in the periacrosomal plasma membrane (PAPM) of boar spermatozoa during incubation in capacitation medium was examined by the freeze-fracture technique. In the preservation medium (PM) group, the major small (about 8 nm) intramembranous particles (IMP) and the minor large (10 nm) IMP were distributed evenly in the PAPM. The IMP-free area increased during capacitation. To correct the IMP-free area, arithmetically redistributed (ARD)-IMP density was used for statistical analysis. In the PM group, the mean density +/- SD of large IMP was 379 +/- 64 and 266 +/- 58/microm2, and that of small IMP was 1450 +/- 155 and 672 +/- 252/microm2 in protoplasmic (P) and external (E) faces, respectively. During capacitation, the significant (P0.01) reduction of large IMP density was encountered only in the E face of a few incubation groups, while that of the small IMP density occurred in the P face by 2 h. Consequently, reduction of the total IMP density of both faces was not significant in the large IMP, but it was significant (P0.01) in the small IMP. One-fifth of the total small IMP density reduced by 2 h. Filipin-sterol complexes (FSC) were numerous in the PAPM, and FSC-free areas also increased during capacitation. The mechanism of IMP-free area formation and the behavior of the small IMP in the PAPM during capacitation were discussed in relation to membrane stability.

To understand textural changes that occur during processing of potatoes, a more comprehensive understanding of the mechanical properties of potato tubers is desirable. Specimens of potato parenchyma had their turgor osmotically adjusted to be either fully turgid or flaccid. Control specimens at normal turgor were also studied. Density of the specimens was measured using Archimedes' principle. The storage (G′) and loss (G″) moduli of the complex shear stiffness were measured in a rheometer. A weak positive relationship between G′ and density was apparent, but only for the osmotically adjusted specimens. This was true regardless of whether specimens were fully turgid or flaccid. However, no such relationship was observed for the control (normal turgor) specimens, which was probably due to slight variation in turgor pressure affecting G′ independently of the effect of density on G′, and so masking the effect of density on shear stiffness. A positive relationship between G″ and density was observed, but only for flaccid specimens. This relationship was putatively assigned to shear strain energy dissipation by starch granule movement in a viscous protoplasm.

SUMMARY Disassembly and reassembly of cortical microtubules (MT) during and after segregative cell division (SCO) in Dictyosphaeria cavernosa (Forssk.) Borgesen were observed using fluorescence microscopy. Parallel cortical MT in a mother cell were intact just after the initiation of SCD, but soon circular, MT-free patches appeared. Protoplasmic contraction enlarged the patches, and in these areas, the protoplasm eventually became perforated. Long and undulating cortical MT were arranged densely in the reticulate protoplasm. During further protoplasmic contraction, cortical MT appeared to be random and decreased in density. Finally, short and random cortical MT were present in the segregated protoplasts. Parallel cortical MT reassembled in the expanding daughter cells. After the daughter cells came in contact with one another, a radial system of cortical MT was constructed at the side that faced the inside of the mother cell wall. A microtubule inhibitor (amiprophos methyl, APM) had no effect on SCO. Segregative cell division was not induced directly by mechanical wounding. A comparison between SCO and wound-induced protoplasmic contraction was made.

Twelve heterokaryotic strains of Heterobasidion annosum (Fr.) Bref. containing nuclei and mitochondria derived from British and North European populations were prepared by pairing homokaryotic strains and isolating hyphal tips from either side of interaction interfaces. Conidia derived from the heterokaryons had high germinability and were predominantly uninucleate. The nuclear genotypes recovered from these conidia were predominantly nonresident in origin, reflecting the marked asymmetry m nuclear ratios (as high as 9:1) in favour of invasive nuclei that developed in the mycelium. In spite of this asymmetry, the heterokaryons had similar phenotypes to the resident homokaryons that they were derived from. Whereas the relative ability of sib-related nuclei to become established in a homokaryon was about equal in sympatric protoplasm, it could be very different in allopatric protoplasm. Post-germination mortality due to the cessation of development following transfer of germlings to fresh medium was on average similar for allopatric and sympatric conidia, but there was a marked trend for reduction in mortality as nuclear ratio asymmetry increased. Homokaryons derived via conidia from a common heterokaryon exhibited less somatic incompatibility when paired together than did the original, basidiospore-derived strains. These findings indicate that phenotype-genotype relationships resulting from allopatric matings, such as could occur following geographical transposition, are liable to differ radically from those in sympatric matings and so have potentially profound effects on resident population structure.

Freeze-fracture electron microscopy was used to investigate intramembranous particle (IMP) densities and particle distributions in the plasma membrane and tonoplast of the cells of secreting and nonsecreting leaves of Avicennia germinans (L.) Steam. Intramembranous particle densities of the protoplasmic (P) and exoplasmic (E) face of the plasma membrane and tonoplast were significantly higher in hypodermal cells of secreting leaves than of nonsecreting leaves. In contrast, no significant differences in the frequency of intramembranous particles were found in any membrane faces of secreting or nonsecreting mesophyll cells. However, particle densities were higher in the plasma membrane and tonoplast of the mesophyll cells, compared to the hypodermal cells, with the exception of the P-face of hypodermal plasma membranes of secreting tissue, which had the highest particle density measured. Particle distributions were dispersed and no discernible patterns such as paracrystalline arrays or other multi-IMP structures were observed. Results support the hypothesis that secretion is coupled to changes in membrane ultrastructure, and the possibility that salt secretion is an active process driven by integral membrane proteins such as the H+/ATPase. Additionally, the hypodermal cells of the leaf may function as storage reservoirs for salt as well as water, suggesting a regulatory role in salt secretion. Freeze-fracture electron microscopy (FFEM) is a useful

Water permeability and cytoplasmic viscosity and straming were investigated in seedlings of two Hordeum vulgare cultivars differing in salt tolerance. Six-day-old seedlings were grown for 4 additional days in Hoagland solution with and without 100 mM NaCl added. Observations and measurements were made in subepidermal cells of teh coleoptile sing plasmolytic and centrifugation methods and recordings of the speed of movement of microsomes

The supramolecular organization of the plasma membrane of apical cells in shoot filaments of the marine red alga Porphyra yezoensis Ueda (conchocelis stage) was studied in replicas of rapidly frozen and fractured cells. The protoplasmic fracture (PF) face of the plasma membrane exhibited both randomly distributed single particles (with a mean diameter of 9.2 ± 0.2 nm) and distinct linear cellulose microfibril-synthesizing terminal complexes (TCs) consisting of two or three rows of linearly arranged particles (average diameter of TC particles 9.4 plusmn; 0.3 nm). The density of the single particles of the PF face of the plasma membrane was 3000 μm−2, whereas that of the exoplasmic fracture face was 325 μm−2. TCs were observed only on the PF face. The highest density of TCs was at the apex of the cell (mean density 23.0 plusmn; 7.4 TCs μm−2 within 5 μm from the tip) and decreased rapidly from the apex to the more basal regions of the cell, dropping to near zero at 20 μm. The number of particle subunits of TCs per μm2 of the plasma membrane also decreased from the tip to the basal regions following the same gradient as that of the TC density. The length of TCs increased gradually from the tip (mean length 46.0 plusmn; 1.4 nm in the area at 0–5 μm from the tip) to the cell base (mean length 60.0 plusmn; 7.0 μm in the area at 15–20 μm). In the very tip region (0–4 μm from the apex), randomly distributed TCs but no microfibril imprints were observed, while in the region 4–9 μm from the tip microfibril imprints and TCs, both randomly distributed, occurred. Many TCs involved in the synthesis of cellulose microfibrils were associated with the ends of microfibril imprints. Our results indicate that TCs are involved in the biosynthesis, assembly, and orientation of cellulose microfibrils and that the frequency and distribution of TCs reflect tip growth (polar growth) in the apical shoot cell of Porphyra yezoensis. Polar distribution of linear TCs as “cellulose synthase” complexes within the plasma membrane of a tip cell was recorded for the first time in plants.

The feeding apparatus of Kalablepharis ovalis (isolated from a freshwater impoundment in Colorado) and Katablepharis clone G-2 (isolated from the littoral of the Black Sea near Yalta in the Crimea) consists of inner and outer oval-shaped arrays of microtubules that begin at the anterior end of the cell and pass into the posterior of the cell. Each array of microtubules contains groups of microtubules with two to eight microtubules per group depending on the position of the array in the cell. A specialized area of the plasma membrane, the mouth, occurs at the anterior end of the cell. The mouth is oval with the long axis oriented dorsoventrally and consists of a raised ridge surrounding a central depression. The anterior end of the microtubules of the inner and outer arrays supports the raised ridge of the mouth. In freeze-fracture replicas, the protoplasmic face of the plasma membrane contains intramembrane particles on the raised ridge of the mouth. Three small membrane-cisternae occur on the protoplasmic side of the plasma membrane in the area of the mouth. Katablepharis clone G-2 also has five or six additional large membrane-cisternae associated with the inner microtubular array in the anterior portion of the cell. These larger membrane-cisternae do not occur in K. ovalis. Vesicles with electron-dense contents occur in association with the microtubular arrays. Katablepharis ovalis has a second type of vesicle containing a single-membrane profile associated with the microtubule arrays. The structure of the microtubular arrays in Katablepharis is compared with similar structures in suctorian ciliates and dinoflagellates.

The fine structure of the plasma membrane in spores of the microsporidium Nosema algerae, a pathogen of mosquitoes, was examined in the resting condition and after the spores were stimulated to germinate in vitro. Slow penetration of resin caused collapse of the germinated spores. Thin sections of germinated spores showed peculiar membrane infoldings that were never found in ungerminated samples. Analogous germination-dependent configurations of the plasma membrane were observed in freeze-fractured preparations of spores either fixed and impregnated with glycerol prior to freezing, or rapidly frozen with liquid propane while in the process of germination. In every case, the replicas presented germinated spores with indentations in the protoplasmic face of the plasma membrane, and apparently complementary blunt spines on the external face, that were absent in ungerminated spores. It suggests that these alterations of the plasma membrane result from a structural adjustment to a spontaneous contraction of the spore case after germination. We discuss this interpretation with regard to conflicting views on the nature of such morphological features.

summary In primary leaves of Vigna sinensis Endl. seedlings growing in the presence of colchicine, some giant polyploid cells at the phloem pole of the vascular bundles differentiate into an extraordinary cell type acquiring most of the prominent features of the sieve elements. These aberrant sieve elements (a-SEs) show some exceptional features not found in normal sieve-tube elements. A heavy secondary thickening is deposited on their walls, which in surface view exhibits a reticulate or ‘pitted’ appearance. The thickenings reach the same depth into the cytoplasm and show a diffuse orientation of cellulose microfibrils. Amorphous callose is deposited around some fine cytoplasmic strands penetrating the secondary wall up to the primary one along the longitudinal and particularly the transverse walls. In the latter walls sieve pores are not formed. At first, the a-SEs undergo a partial protoplasmic degradation like normal sieve-tube elements but finally autolyse completely. During this process, the major portion of the unmasked primary and secondary wall is dissolved. The observations show that (a) a vascular bundle initiation and development proceeds in the affected primary leaves, in the absence of cell divisions.‘Vascular bundles' are formed consisting of a single row of cells, in which a-SE differentiation dominates. (b) The ‘sieve element differentiation’ is initiated without differential divisions. (c) Although the microtubules arc absent, the cells determined to become a-SEs activate another morphogenetic mechanism to control a more or less patterned deposition of a secondary wall layer.

We have examined the plasma membrane of cortical and internodal cells of Chara globularis var. capillacea (Thuill.) Zanev. using rapid-freezing and freeze-fracturing techniques. The non-etched image of the protoplasmic face reveals particle rosettes, and also reveals ridges which can be correlated with cortical microtubules. Since both rosettes and microtubular ridges can thus be viewed simultaneously, we have looked for a spatial relationship between them, but have found them to be essentially independent. We have found that the density of particle rosettes is a function of age and of type of cell. Groups of pits may represent the complementary exoplasmic component of the rosettes.

Protoplast regeneration from extruded cytoplasm of the multi-cellular marine green alga Microdictyon umbilicatum (Velley) Zanardini (Cladophorales, Anadyomenaceae) was investigated. The early process of protoplast formation is comprised of two steps: agglutination of cell organelles into protoplasmic masses followed by generation of a temporary enclosing envelope around them. Agglutination of cell organelles was mediated by a lectin-carbohydrate complementary system. Three sugars, D-galactosamine, D-glucosamine, and a-D-mannose, inhibited the agglutination process, and three complementary lectins for the above sugars, peanut agglutinin, Ricinus communis agglutinin and concanavalin A, bound to the surfaces of chloroplasts. Agglutination assay using human erythrocytes showed the presence of lectins specific for the above sugars in the algal vacuolar sap. The lectin has been purified by the use of D-mannose agarose affinity column. Its Molecular weight was shown to be 36,000 dalton by SDS-PAGE gel electrophoresis. When the basic regeneration process was accomplished, the cells chose one of two developmental strategies; about 70% of one-celled protoplasts transformed into reproductive cells within two weeks after wounding, while others began cell division and grew into typical Microdictyon plants. Quadriflagellate swarmers were liberated from the reproductive cells, and they germinated into mature plants

Ultrastrucural and molecular data were used to examine a new alga (CCMP2000) collected from the Arabian Sea. Nonmotile vegetative cells are typically oblong to ovate, solitary and lack a gelatinous envelope. Ultrastructural analyses of these cells revealed the presence of a nucleus located in the posterior portion of the cell. A single large Golgi body with numerous cisternae is located anterior to the nucleus as are numerous profiles of mitochondria possessing tubular cristae. Two peripheral plastids are present having immersed pyrenoids that are traversed by one or more thylakoids. In some cells, the plastids are conspicuously lobed forming finger-like extensions. Nonmotile vegetative cells possess reduced mature and immature flagella as well as a haptonema that are 1 micron long or less. A distinct internal covering and external wall surround the cell protoplasm. The outer wall is apparently composed of simple scales, but the composition (organic or mineralized?) of these scales is unknown. The outer wall may form a protuberance, or ‘foot’, at the posterior end of nonmotile cells. Interestingly, many vegetative cells are infected by a labyrinthulid. Flagellate stages have been observed and possess roughly equal length flagella and a haptonema. Phylogenetic analyses of nuclear 18S rRNA and plastid-encoded rbcL genes indicate CCMP2000 is most closely related to Phaeocystis. However, CCMP2000 does not fit the description of Phaeocystis, and therefore, probably warrants recognition as a new taxon.

A thorough extraction of plasmodia of Physarum polycephalum by sequential treatment with 1% Triton x-100, 0.6 M KI, 4% SDS plus 7 M urea leaves behind an elastic cell ghost, which represents a cytoplasmic matrix protein arranged as a continuous network in all cell regions. The protein is present in the ectoplasm as well as in the endoplasm. The extraction-resistant ghosts reveal filaments 2–3 nm in diameter, perform a conspicuous volume condensation upon the addition of mM-concentrations of di- and trivalent cations and can be partially solubilized in 4.5 M guanidinium chloride plus 25% 2-mercaptoethanol at 70 °C. SDS-gel electrophoresis shows a distinct band at 43,000 daltons and a faint high molecular weight component suggesting a similarity to muscle connectin.

査読付原著論文, インパクトファクター(2.41), 被引用回数(12)

In conformity with earlier results, low-temperature hardening of cabbage seedlings lowered the osmotic potential and increased the permeability to thiourea of the petiole cells. It also decreased the time required for rounding-up of the protoplasts in cells plasmolysed in 1. 5 × isotonic (or higher) glucose or CaCl2 solutions. Solutions of dimethylsulphoxide (DMSO), thiourea, urea, and glycerol each accelerated the rate of rounding-up of protoplasts in plasmolysed cells, compared to the rate in glucose solution of the same hypertonicity. Each also penetrated the cell membranes as indicated by deplasmolysis. Only in the case of DMSO, in which there was very rapid deplasmolysis (5–6 min), was this rounding-up due to protoplast expansion. In the case of thiourea (deplasmolysis within 30–60 min) rounding-up occurred almost immediately (less than 2 min), before protoplast expansion was sufficient to induce it. It was concluded that the accelerated rounding-up was due to a rapid osmotic adjustment in the protoplasm by the penetrating solution, which increased its water content and decreased its viscosity.

The parenchyma cells of three vegetable tissues varying in starch content as well as in textural response to freeze-thawing were studied ultrastructurally before and after controlled freeze-thaw regimes. Similar tissue samples were also studied after blanching and after the blanch-freeze-thaw combination. Subcellular structures were altered more drastically by blanching than by freeze-thawing. There was much less fine structural disruption in the high starch tissue (green pea cotyledon) than in the tissues of lower starch content (spinach leaf and green bean pod) following all processing treatments. As judged by sensory evaluation, peas also underwent less textural change on processing than the other tissues studied. The minimal ultrastructural change observed in peas may be associated with certain cell characteristics: high starch content, abundant protoplasmic structure, and resultant low degree of vacuolation. It is concluded that - of these - the starch granule component is the major contributor to texture. This probably applies in the case of most processed vegetable tissues of relatively high starch content. The protective role of cellular starch is discussed in relation to fine structure retention and to texture.

The synthesis and localization of α-amylase were studied in Bacillus stearothermophilus AN002 at 40, 45, 50 and 55 °C and also during early exponential, late exponential and stationary phases of growth. The extracellular α-amylase synthesis was highes at 50 °C and at stationary growth phase. Accumulation of intracellular α-amylase was observed in cells grown at 40 °C and was distributed in all the cell fractions. At 50 and 55 °C the cell did not have α-amylase in the protoplasm or protoplamic membrane. The synthesis and externalization of extracellular enzyme are two processes and the externalization is controlled by growth temperature and cell age.

Wound healing in most of the Siphonocladales investigated differs markedly from healing processes known in other coenocytic green algae. No wound plug is evident during healing in Ernodesmis verticillata (Kutzing) Borgesen, Boergesenia forbesii (Harvey) Feldmann, Cladophoropsis membranacea (C. Agardh) Borgesen, Siphonocladus tropicus (Crouan) J. Agardh, Struvea elegans Borgesen, Struvea sp. and Valonia spp. The wound response in these genera involves substantial protoplasmic motility which includes retraction of the cell contents from the wound site. The protoplasm then either closes around the central vacuole (e.g. Ernodesmis) or breaks up into numerous spherical protoplasts (e.g. Valonia ventricosa J. Agardh). An intermediate pattern of healing is present in Cladophoropsis where the protoplasm usually separates into a small number of portions that individually heal in a manner similar to Ernodesmis. In all cases, the protoplasts resulting from wounding are viable. Struvea anastomosans (Harvey) Piccone, Chamaedoris sp. and Boodlea sp. are unusual in producing a distinct wound plug during healing, thereby resembling the mode of healing reported in various codialean and dasycladalean genera. It is hypothesized, that wound-induced protoplasmic motility in the Siphonocladales involves the same cellular mechanisms that segregate protoplasm during cell, division.

The two unit membranes which envelope the endosymbiont of the trypanosomatid protozoon, Blastocrithidia culicis, were studied using the freeze-fracture technique. The distribution of the intramembranous particles on both fracture faces of the inner and outer membrane of the endosymbiont was analyzed in the replicas. The protoplasmic face of the inner membrane (PFi) had a higher density of membrane particles than that observed on the extracellular face (EFi), a pattern typical of plasma membranes. The extracellular face of the outer membrane (EFo) presented a density of membrane particles much higher than that observed on the P face of the outer membrane (PFo) a distribution significantly different from that found in the inner membrane of the endosymbiont and in the plasma membrane of the protozoon, but similar to that observed in Gram-negative bacteria. The data obtained support the idea that the endosymbiont of trypanosomatids represents a Gram-negative bacterium-like microorganism enveloped by two unit membranes and lacking a peptidoglycan layer and which lives in direct contact with the cytoplasm of the protozoon.

Leakage of ions from a thawed tissue is a common phenomenon of freezing injury. This leakage is usually assumed to be due to loss of membrane semipermeability or membrane rupture by freezing injury. Freeze injured, yet living, onion (Allium cepa L.) epidermal cells were used to study alterations in cell membranes that result in leakage of ions. In spite of a large efflux of ions, freeze injured cells could be plasmolysed and they remained plasmolysed for several days just like the unfrozen control cells. Injured cells also exhibited protoplasmic streaming. Passive transport of KCl, urea and methyl urea across the cell membranes of injured and control cells was also studied. No difference could be detected for the transport rates of urea and methyl urea between control and injured cells. However, a dramatic increase in the transport rate of KCl was found for the injured cells. Depending upon the extent of initial freezing injury, an increase or a decrease in injury symptoms was found in the post-thaw period. During the progress of freezing injury, 10 days after thawing, a swelling of the protoplasm was seen in the irreversibly injured cells. In spite of this swelling, these cells could be plasmolysed. It appears that the high amount of K+ that leaks out into the extracellular water, due to freezing injury, causes protoplasmic swelling by replacing Ca2+ in the plasma membrane. We conclude that protoplasmic swelling is a sign of secondary injury. The results presented in this study show that membrane semipermeability is not completely lost and membrane rupture does not occur during the initial stage of freezing injury. In fact, the cells have the ability to repair damage depending upon the degree of injury. Our results show there are specific alterations in membrane semipermeability (e.g., transport of K+) which could be repaired completely depending on the degree of injury. These findings suggest that ion leakage due to freezing injury is due to alteration in the membrane proteins and not in the membrane lipids.

Analyses of the ultrastructural states of preservation seen in fossil angiosperm mesophyll cells indicate that plastids are more commonly found in portions of protoplasts (= microprotoplasts) lacking nuclei than in microprotoplasts containing nuclei. Of the 4,498 cells examined in serial thick sections, less than 1.8% had continuous protoplasts, while the remaining 98.2% had from 2 to 3 microprotoplasts or lacked any discemable internal structure. Where nuclei and plastids were found in the same cell (21.3%), only 29.5% had these two organelles in the same microprotoplast, while 70.5% had nucleate microprotoplasts lacking plastids and enucleate microprotoplasts with well preserved plastids. Over 64% of all the cells sampled lacked nuclei but had well preserved plastids. Neobotanical studies indicate nuclei are more stable than plastids, but during microprotoplast formation plastids are more stable in enucleate protoplasts than in those containing nuclei. Senescence and necrosis are triggered by the nuclear genome. The preferential preservation of plastids in fossil angiosperm tissues is interpreted to be the result of the isolation of part of the plastid population from nuclear control due to microprotoplast formation. This hypothesis also may explain the apparent longevity of nuclei over plastids in other fossil cells (spores, pollen, algal tissues) where protoplasmic partitioning may be less frequent.

1. Concentrations of 0.1-10 mM Ouabain do not affect oscillating contractions, when applied externally in physiological solutions. 2. Ouabain has no effect, when applied in solutions of increased sodium- (100 mM) and lowered potassium-concentration (0.1 or zero mM). 3. De novo generation of oscillating contractions in protoplasmic drops is not suppressed in Ouabain-solutions. 4. Biochemical studies of Na-K-ATPase did not show any Ouabain sensitive ATPase-activity. 5. Reaction of veins on high concentrations (300 mosm) is discussed as to be a physical effect. 6. It is concluded that no Na-K-ATPase is engaged in triggering oscillating contraction automaticity.

SUMMARY The fine structure of vegetative and reproductive gametophytes of Derbesia tenuissima is described. Development of the gametangium and release of the gametes progress as follows: (1) In initial stages of gametangium formation, prior to 24 hr before gamete release, there is an accumulation and proliferation of nuclei, chloroplasts, and other organelles. (2) This is followed by separation of the gametangium from the rest of the plant by a gametangial membrane; segregation of organelles into gametes has begun by 12 hr before release and the process is completed by 2.5 hr before release. (3) Enzymatic wall dissolution of the pore area occurs between 2.5 and, 12 hr before normal lights-on time. (4) The release mechanism appears to be an instantaneous light-induced increase in lurgor pressure rupturing the weakened pore area, of the wall and causing a forcible expulsion of the gametes. (5) Following release, the pore is sealed by organellar debris and the gametangial membrane. Additional wall layers are presumed to be laid down internal to the plugged pore by the vegetative protoplasm which migrates into the area.

SUMMARY The dyes safranin and basic fuchsine as well as ferric salts enter the stele when applied as dilute solutions to intact root parts where Casparian strips are well developed. As the entrance is not hampered when the protoplasm has been killed or its activity and permeability diminished by low temperature the most likely way of entrance is through the cell walls. In the Casparian strips no fatty substances could be detected. As soon as traces of fatty substances are found in the ageing exodermis all entrance into cortex and stele of the substances used is blocked.

The digestion of dandelion (Taraxacum officinale) pollen by adult worker honeybees (Apis mellifera Linn.; Hymenoptera: Apidae) was initiated at the germination pores. 30 min after feeding, pollen had reached the anterior midgut and the germination pores had become swollen. This permitted further removal of protoplasm during the next 2 h of digestion as the pollen passed into the middle portion of the midgut. 3 h after feeding, pollen grains had reached the posterior midgut where some had ruptured to release both ‘naked’ protoplasm and masses of protoplasm but many remained intact or were only partially digested; undigested pollen grains passed unchanged to the rectum. The lipid-rich pollenkitt layer was removed from the exine during digestion. Our studies indicate that dandelion pollen was not utilized completely by honeybees.

The ultrastructure of Blastocystis hominis was investigated by the freeze-fracture method. Freeze-fracture replicas of the membranes of B. hominis and its organelles were studied with special regard to the density and distribution of the intramembranous particles (IMF's). On all membrane replicas, the concentration of IMF's on the protoplasmic face (P face) invariably was greater than on the exoplasmic face (E face). On the P face, IMP's were heterogeneously distributed in dense aggregates, alternating with particle-free, smooth surface areas. Occasionally, small depressions and protrusions were observed in these areas. On the membrane of the central vacuole, invaginations into the vacuole were frequently observed within the smooth surface regions. Since most of the granules in the central vacuoles had no IMF's, it seems likely that the intervacuolar granules were formed from these invaginations of the vacuole membrane. The width of the intermembrane space between the inner and outer membranes of the nuclear envelope was uneven, with regions of relative narrowness interspersed with regions of expansion. Nuclear pores were localized within the narrow portions of this space. A nucleus, apparently in the process of dividing, was observed enclosed within an intact outer membrane. Division of the outer membrane would then result in the formation of two discrete nuclei.

Diel variations in the growth and nutrient uptake rates of Chaetoceros sp. were observed in 2,000-liter outdoor continuous cultures. Nitrate uptake was continuous and independent of the light-dark cycle at dilution rates of 1.5 day-’ and less. At a dilution rate of 2.0 day-l, nitrate uptake and net cellular organic nitrogen production varied in synchrony, peaking early in the photoperiod and decreasing to a diel minimum during the dark period. Growth appeared to be limited by nitrate uptake at the slower dilution rates and by the rate at which nitrogen could be incorporated into new protoplasm at the highest dilution rate. The latter Gas probably light limited.

“Cholinergic” synapses of the bullfrog sympathetic ganglion cells were investigated with thin sectioning, complementary freeze-fracturing, and deepetching methods after glutaraldehyde fixation. The protoplasmic (-fracture) face (PF) of the postsynaptic membrane was characterized by intramembranous particles (IMPs), 3,500/μm 2 in density, consisting of larger particles, 10–12 nm in diameter, and smaller ones, 8–9 nm; the complementary exoplasmic (-fracture) face (EF) contained larger and smaller IMPs, 750/μm 2 in density, and numbers of pits. By close inspection of the sections and freeze-fracture replicas at high magnification and with deep-etching in particular, it was concluded that aggregated IMPs might represent transmembranous components and that the particulate entities existing in the postsynaptic active zones might be larger in number than those exposed to view and counted here in the “cholinergic” synapses. An individual IMP often appeared to consist of five or six subunits arranged in a rosette with a central pit. These findings suggest that the aggregated IMPs, particularly the larger ones, may be closely related to the structure of the nicotinic ACh receptor-ion channel complex.

Freeze-etch electron micrographs of haemolysing erythrocytes and isolated erythrocyte membranes frozen using a liquid propane jet-freezer reveal fracture faces very different from those seen after conventional freezing by dipping the specimens into partly solidified Freon 22. Instead of the rather smooth extracellular fracture faces found after conventional specimen freezing, extracellular fracture faces exhibiting large amounts of fibre-like structures are seen after liquid propane jet-freezing of these specimens. No such structures were found in normal red blood cells. When isolated erythrocyte membranes are frozen under conditions favouring spectrin-actin release, freeze-etch micrographs reveal an apparent continuity between the fibre-like structures on the extracellular fracture face and the long fibre-like structures which extent from the protoplasmic surface of the erythrocyte membrane. These results suggest that liquid propane jet-freezing is capable of revealing a structural difference between the membrane of haemolysing and nonhaemolysed red blood cells, and that this difference is related to the fibrous, peripheral proteins of the membrane.