Showing papers in "Protoplasma in 1978"
TL;DR: The intense fluorescence induced in the traditional “callose” sites, sieve plates, around pitfields and in new cell walls is probably related to localized differences in the structural packing of wall polymers.
Abstract: Commercial aniline blue dyes are heterogeneous and variable. We have isolated and purified the fluorochrome from water soluble aniline blue. This fluorochrome fluoresces weakly with a maximum emission around 455 nm but the fluorescence is shifted to longer wavelengths (500–506 nm) when complexed with isolated β-1,3-glucans, cellulose or mixed-linked glucans. A similar intense fluorescence is observed in sieve plates, new cell walls and around pitfields in the presence of the fluorochrome. The fluorescence induced by the aniline blue fluorochrome does not specifically indicate the presence of β-1,3-glucans. Indeed most wall features are induced to fluoresce to some extent by the fluorochrome. However, fluorescence is modified by lignins and phenolics. Furthermore the intense fluorescence induced in the traditional “callose” sites, sieve plates, around pitfields and in new cell walls is probably related to localized differences in the structural packing of wall polymers.
190 citations
TL;DR: Epifluorescence microscopy with chlorotetracycline fluorescence was used to visualize the Ca2+ distribution in germinating pollen grains and growing pollen tubes of Lilium longiflorum and shows a gradient with the highest fluorescence at the growing tip.
Abstract: Epifluorescence microscopy with chlorotetracycline (CTC) fluorescence was used to visualize the Ca2+ distribution in germinating pollen grains and growing pollen tubes ofLilium longiflorum. The intensity of the fluorescence shows a gradient with the highest fluorescence at the growing tip. Added external Ca2+ influences the intensity of the gradient in germinating grains. Ionophore A 23187 treated pollen tubes do not show the fluorescence gradient with CTC. These results are interpreted as evidence for the role of a Ca2+ gradient in pollen tube tip growth.
121 citations
TL;DR: Histochemical studies indicate that lipids and polyphenolics are components of the epidermal and hypodermal cell walls, and both layers are resistant to the wall-degrading enzyme Driselase and to concentrated sulphuric acid, whereas the cortex is digested with both treatments.
Abstract: Cell walls of mature epidermal and hypodermal cells are autofluorescent when viewed under ultraviolet or blue light. This autofluorescence develops in a centripetal direction, beginning in the outer tangential wall of the epidermis and ending in the inner tangential wall of the hypodermis. The intercellular regions between the epidermis and hypodermis and between the hypodermis and the cortex are dense and also become autofluorescent. Although the walls of the hypodermis provide a barrier to the movement of a high molecular weight fluorescent dye, the walls of the epidermis are permeable. Histochemical studies indicate that lipids and polyphenolics are components of the epidermal and hypodermal cell walls. Both layers are resistant to the wall-degrading enzyme Driselase and to concentrated sulphuric acid, whereas the cortex is digested with both treatments. Observations with the transmission electron microscope show that a complex suberin lamella encases each hypodermal cell but is absent from the epidermis. However, the outer tangential wall and radial walls of the epidermal cells are complex in that layers of different densities are present. Some of these layers, as well as the intercellular regions and the radial walls of the hypodermal cells, bind ferric ions when tissue is fixed in ferric chloride-glutaraldehyde indicating the presence of poly-phenolics in these regions. An extracellular layer covering the outer tangential wall of the epidermis stained positively with a number of histochemical tests for polyphenolics.
83 citations
TL;DR: The results of anatomical studies of the development of these secondary growth forms by light and scanning electron microscopy suggest that shoots and embryo-like structures can arise directly from cells of the primary scutellum without an intervening callus phase.
Abstract: Cells of the scutellum of immature embryos ofSorghum bicolor plated onto an agar medium containing 2,4-D give rise to shoots and embryo-like structures and to some callus. Some of the embryo-like structures later develop into typical sorghum embryos complete with scutellum, coleoptile and coleorhiza. The results of anatomical studies of the development of these secondary growth forms by light and scanning electron microscopy suggest that shoots and embryo-like structures can arise directly from cells of the primary scutellum without an intervening callus phase. In some cases it appears that the scutellum of the secondary embryos arises by folding of the scutellum of the sexual embryo and does not arisede novo. In other cases the structures arise from single cells. No evidence was found to indicate that organized structures arose from proliferating callus cells. The unorganized callus which arises initially is not capable of growth through continuous subculture; it produces a purple-black pigment and rapidly becomes necrotic. The significance of these observations is discussed in relation to present views on morphogenesis in cereal cell cultures and their implications forin vitro cell genetics.
78 citations
TL;DR: The anthers showed the capacity for androgenesis and evidence is presented that the plantlets developed from single microspores, and Haploid karyotypes were observed in the root menstem cells in three plantlets.
Abstract: Horsechestnut anthers were isolated from flower buds in various stages of development and cultivated in the presence of auxin and kinetin. The anthers showed the capacity for androgenesis and evidence is presented that the plantlets developed from single microspores. Haploid karyotypes were observed in the root menstem cells in three plantlets.
69 citations
TL;DR: It is hypothesized that the pollen of Lilium longiflorum needs Ca2+ to sustain oriented exocytosis at the pollen tube tip, and the ionophore A 23187 seems to interfere with the electrical pulse/Ca2+-orientation mechanism of exocyTosis by equilibration of the Ca2-gradient.
Abstract: The effects of the cationophore A 23187 on growing pollen tubes ofLilium longiflorum and on pollen germination were testedin vitro, and measured light microscopically. The ionophore is a very potent inhibitor of pollen tube growth: ionophore contentrations down to 10−7 M stop tip growth. Cytoplasmic streaming is less sensitive: Only with added external Ca2+ and higher concentrations of the ionophore the cytoplasmic streaming is stopped. Pollen germination is less sensitive to ionophore than pollen tube growth at later stages. The ionophore inhibition is partially reversible in a medium containing no added external Ca2+, but is not reversible in a Ca2+-enriched medium. EDTA addition to the medium prevents pollen germination and growth totally. It is hypothesized that the pollen ofLilium longiflorum needs Ca2+ to sustain oriented exocytosis at the pollen tube tip. The ionophore A 23187 seems to interfere with the electrical pulse/Ca2+-orientation mechanism of exocytosis by equilibration of the Ca2+-gradient.
64 citations
TL;DR: Electron diffraction patterns obtained from selected areas of disencrusted microfibrils isolated from the primary cell wall of cotton fibers suggest that the crystalline structure of the primary wall cellulose is similar to that of cellulose IVI and is best explained in term of native cellulose I crystals having good longitudinal coherence but with poor lateral organization of the network of inter chain hydrogen bonds.
Abstract: Electron diffraction patterns have been obtained from selected areas of disencrusted microfibrils isolated from the primary cell wall of cotton fibers. The resultant fiber diagram has the same meridional repeat distance as a corresponding pattern of secondary wall microfibrils but differs markedly in the equatorial reflections. The primary wall diagram displays only two strong equatorial reflections centered at 0.570 nm and 0.416 nm. The similarity of these spacings with those of cellulose IV suggests that the crystalline structure of the primary wall cellulose is similar to that of cellulose IVI and is best explained in term of native cellulose I crystals having good longitudinal coherence (i.e., coherence along the length of the microfibrils) but with poor lateral organization of the network of inter chain hydrogen bonds. Similar results were also obtained for other primary wall specimens.
60 citations
TL;DR: It was concluded that desiccation-induced changes in cell structure are tissue-specific and occur on a cell-by-cell basis rather than in all cells of a tissue at once.
Abstract: Desiccation-induced alterations in cell structure were investigated in sunflower (Helianthus annum L.) leaves using light and electron microscopy. Desiccation was imposed by withholding water from the tissue, and all tissue fixation was carried out under isosmotic conditions. In addition to shrinkage of the vacuoles and intercellular spaces caused by water loss, the significant features of cell desiccation were the appearance of lipid droplets and vesicles close to dictyosomes, and plasmalemma and/or tonoplast breakage in the mesophyll cells. Breakage was followed by massive loss of cell organelles except for the thylakoid membranes of the chloroplasts, which retained much of their integrity even in the air-dried state. Plasmalemma and tonoplast disruption began in a few cells at water potentials of — 15 bars (relative water contents of 47%) and went to completion below —26 bars (relative water contents less than 28%) in the leaf mesophyll. Typically in this tissue, net photosynthesis becomes zero and the tissue becomes increasingly incapable of full rehydration at water potentials below — 20 bars. By contrast, water potentials of — 26 bars had no detectable effects on the phloem tissue. Structural alterations were little influenced by the rapidity of desiccation (a few minutes to as long as four days). It was concluded that desiccation-induced changes in cell structure are tissue-specific and occur on a cell-by-cell basis rather than in all cells of a tissue at once. The concentration of the cytoplasm and the disruption of the plasmalemma and/or tonoplast seem to be central events in the alteration of cell ultrastructure by desiccation.
50 citations
TL;DR: The periodicity of striation in the tailless P-protein crystal of Pisum sativum has been studied in this article, where the periodicity was measured to measure 12 nm.
Abstract: The periodicity of striation, discovered to measure 12 nm in the tailless P-protein crystal ofPisum sativum, is compared with that known in the central body of the tailed P-protein crystal ofPhaseolus multiflorus. A preliminary model advanced to explain the coarse striation in tails accounts for both the wavy outline in longitudinal section and the nearcircular outline in transverse section.
46 citations
TL;DR: During early embryogeny, the development of the suspensor is rapid both in terms of size and fresh weight; structural differentiation can be observed as early as the proembryo stage with the formation of wall ingrowths.
Abstract: During early embryogeny, the development of the suspensor is rapid both in terms of size and fresh weight; structural differentiation can be observed as early as the proembryo stage with the formation of wall ingrowths. Ingrowths first appear in the outer wall of the suspensor cells adjacent to the integumentary tapetum, soon ingrowths begin to form in the inner suspensor cells as well. A basal-terminal gradation in nuclear size exists, with the largest nuclei in the basal suspensor cells. Cytologically, the suspensor cells appear to be very active, especially when the embryo reaches heart stage. Initially, the development of the embryo proper lags behind the suspensor, but its size and fresh weight increase rapidly as development proceeds. The volume of the liquid endosperm rises most rapidly during the late heart stage; and it is absorbed soon after. A cellular endospermic sheath surrounds the embryo, separating it from the liquid endosperm. Structural differentiation also occurs in the cellular endosperm cells with the formation of wall ingrowths in those cells that abut directly onto the integumentary tapetum. Both the suspensor and the cellular endosperm appear to remain active through the maturation of the seed. Storage bodies are formed in the cotyledons as well as in the embryonic axis. In the suspensor and the cellular endosperm, starch grains and lipid bodies can be found at the maturation stage.
46 citations
TL;DR: Callus induction and development from the immature Vicia faba cotyledons, which contain diploid and endoreduplicated nuclei, followed the following sequence of nuclear events.
Abstract: Expiants of immature cotyledons (2 cm in length) ofVicia Raba (2 n=12) were grownin vitro onMitchell andGildow's (1975) medium supplemented with auxin (either IAA or 2,4-D) alone or auxin and kinetin in many possible combinations of concentrations.
TL;DR: Light and electron microscopic investigations of fruit-body primordia of the basidiomycetes Schizophyllum commune and Coprinus cinereus showed that hyphal fusions are common in specific areas of the fruit- body primordias of both species.
Abstract: Light and electron microscopic investigations of fruit-body primordia of the basidiomycetesSchizophyllum commune andCoprinus cinereus showed that hyphal fusions are common in specific areas of the fruit-body primordia of both species. In these areas conspicuous amounts of a mucilaginous substance occur between the closely packed hyphae. A possible function of this mucilage is to aid the adhesion of hyphae prior to fusion. In the fruit-body primordium ofCoprinus cinereus the dolipore/parenthesome septum is surrounded by an additional hemispherical membranous cap (outer cap). Such a cap was never found inSchizophyllum commune fruit-body primordia.
TL;DR: During the interval of 11 to 24 hours following wounding, there is a gradual extension of the retracted cytoplasm to the inner surface of the internal wound plug with a corresponding resorbtion of some of the vesiculate material.
Abstract: The cytological changes which accompany wounding and wound recovery in the coenocytic algaCaulerpa simpliciuscula have been studied using both light and electron microscopy. Within one minute of wounding, there are three responses.
1.
The formation of a gelatinous plug on the surface of the wound. The material contributing to this external plug appears to be formed from vacuolar contents which undergo sol to gel transformation following extrusion under turgor pressure.
2.
The formation of an internal wound plug of different composition to the external plug. Deposition of the internal wound plug continues for up to 11 hours following wounding. On the basis of staining reactions this material appears to be either a sulphated glycoprotein, or a mixture of protein and sulphated polysaccharide.
3.
The retraction of cytoplasm away from the wound site, and the formation of a large number of vesicles between the cytoplasm and the surface of the internal wound plug. The formation of these vesicles appears to result from the re-organization of membrane components present in the unwounded cytoplasm into the surface membranes of the vesicle.
TL;DR: Differentiation of the female gametangium in Cutleria bancockii Dawson is described, with abundant osmiophilic material present in the cytoplasm subjacent to thegametangial surface.
Abstract: Differentiation of the female gametangium inCutleria bancockii Dawson is described. Four series of mitoses result in a 16-locule structure (four tiers of four cells each). The organelles in each locule become polarized after partitioning is complete, with the mitochondria lying near the longitudinal axis of the gametangium. The nucleus and plastids are centrally located, with abundant osmiophilic material present in the cytoplasm subjacent to the gametangial surface. Both electron density and Toluidine Blue 0 staining of the material increase. Two flagella are then produced: one becomes tightly appressed to the plasmalemma near its base, and the other is free. A prominent eyespot forms in the plastid nearest the developing flagella. Golgi and endoplasmic reticulum vesicles are prolific in this region and seem to be involved with mastigoneme production and deposition on the free flagellum. Immediately beneath the plasmalemma, flagellar rootlet tubules emanate from amorphous masses near the basal bodies. Some of these tubules are associated with the eyespot. Most of the osmiophilic material is then secreted into the extracytoplasmic spaces while the gametes are rounding up. Granular-cored vesicles may be involved with pore formation and gamete release.
TL;DR: The cytoplasmic transport of secretory products in a non-visible form may explain the involvement of several cell compartments and the heterogeneity of thesecretory products.
Abstract: The aim of the present study has been to elucidate the cytology of the glandular stigma inLycopersicum peruvianum Mill. and the mechanism of the secretory process during the stigma development. The glandular stigma (papillae and superficial stigmatic tissue) has been studied by light and electron microscopy (S.E.M. and T.E.M.). At anthesis, the longitudinal intercellular spaces are filled with exudate in the form of heterogeneous droplets and form an intercommunicating system which allows transmitting tissue to communicate with superficial papillae. The presence of cytoplasmic droplets similar in appearance to the exudate has been noted in the developing stigmatic tissue. Cytoplasmic events which may be related to their production include transitory vacuolar accumulations, modifications of the morphology of plastids and development of smooth endoplasmic reticulum. At anthesis, observations possibly related to the origin of these droplets include their contiguity with endoplasmic reticulum cisternae and their relationship to the Golgi apparatus. Some observations suggest that cytoplasmic droplets are extruded by a process of exocytotic secretion. In addition, the cytoplasmic transport of secretory products in a non-visible form may explain the involvement of several cell compartments and the heterogeneity of the secretory products.
TL;DR: Dilated cisternae (DC) of endoplasmic reticulum were found to be a typical component of stem-, hypocotyledon-, and root vascular parenchyma as well as root cap cells in Brassicaceae and Capparaceae and it is discussed whether it is likely that DC are a site of β-thioglucosidases while it is known that the glucosinolate-containingResedaceae do not contain this organelle.
Abstract: Dilated cisternae (DC) of endoplasmic reticulum were found to be a typical component of stem-, hypocotyledon-, and root vascular parenchyma as well as root cap cells inBrassicaceae (14 species screened) andCapparaceae (7 species). In general, DC are very long, utricular organelles containing proteins and bound by a unit membrane which is studded with ribosomes. In aerial parts of the plants tested the proteins are tubular structures arranged parallel to the DC axis, in roots there ar filamentous proteins. In someBrassicaceae (e.g., Lunaria, Ptilotrichum, Schivereckia) DC are irregularly shaped and contain granular protein material. These forms are discussed to be leading to protein-containing vacuoles as found in companion cells ofTovaria. Since DC do occur in taxa which contain glucosinolates, an EM-cytochemical test for β-thioglucosidases (as first performed byIversen) was applied to some of the species. The results, however, did not prove a specific location of the enzyme inside DC. In addition to questions on the reliability of the method it is discussed whether it is likely that DC are a site of β-thioglucosidases while it is known thate.g., the glucosinolate-containingResedaceae do not contain this organelle. Also,Erythroxylum (Erythroxylaceae) andJacaranda (Bignoniaceae) gave the same precipitations when subjected to the cytochemical test (see “note added in proof”).
TL;DR: A new rhythm, which is probably circadian, is discussed in terms of cytoplasmic streaming and of other circadian rhythms, known to occur in Acetabularia.
Abstract: Young cells ofAcetabularia mediterranea were studied by time lapse cinematography. Rhythmic changes were observed in the optical transmission of the rhizoid and the apex of the cells, respectively. Transmission changes were determined photometrically by single frame analysis. Optical density is at the maximum in the rhizoid, when it is in the minimum in the apex, andvice versa. The rhythm is endogenous, since it persists under constant conditions. The length of the periods is typically circadian. The changes of optical density are caused by chloroplast migrations which are directed towards the apex of the cell at the beginning of the circadian day and towards the rhizoid at the beginning of the circadian night. This new rhythm, which is probably circadian, is discussed in terms of cytoplasmic streaming and of other circadian rhythms, known to occur inAcetabularia.
TL;DR: Several ultrastructural features suggest that the vascular apparatus of Mimosa pudica would be the site of intensive lateral transfer at different levels, specially in motor organs.
Abstract: 1 In motor organs ofMimosa pudica xylem contains living fibriform elements limited by a thick lignified highly pitted wall, whereas in other parts of the plant (stem, petiole, rachis), xylem and protoxylem vessels are closely associated with parenchyma cells which possess wall ingrowths These ingrowths, at the apex of which the plasmalemma and the tonoplast touch, are localized like those of “transfer cells” of C type described byGunning andPate Nevertheless, xylem parenchyma cells differ from cells of C type in several characteristics Moreover, in motor organs, phloem contains cells characterized by wall ingrowths, less abundant on the parts adjacent to the sieve tubes; these cells which are localized near collenchyma cells of primary phloem, look like “transfer cells” of A type defined byGunning andPate; they are absent from internodes, petioles and rachides 2 In motor organs, three types of vascular cells (companion cells, living xylem fibriform elements and protoxylem parenchyma cells) are characterized by reduced vacuolar volumes and well developed membrane systems, as compared with homologuous cells belonging to other parts of the plant 3 A symplastic continuity holds from the middle of motor organs to their cortex: it is provided by the presence, in xylem and phloem respectively, of living fibriform elements and collenchyma cells bearing numerous pit fields containing large numbers of plasmodesmata Several ultrastructural features suggest that the vascular apparatus ofMimosa pudica would be the site of intensive lateral transfer at different levels, specially in motor organs Possible functions of certain structures observed are discussed in relation to some hypotheses relative to excitatory conduction pathways
TL;DR: The fatty acid distribution pattern appeared unaffected by the nature of substrate and climatic conditions and there is a certain similarity in the fatty acid composition in related species.
Abstract: The structure of medullary oil hyphae of twelve endolithic lichen species, belonging to different taxa and colonizing different habitats, was examined by light and electron microscopy. The chemical composition of lipids isolated from the oil hyphae and from two corresponding mycobionts grown in culture was determined. The oil hyphae of the various species appeared in different forms and contained large amounts of lipid in the form of oil globules. The hyphae of mycobionts isolated from two of the endoliths and grown in culture also contained large amounts of lipids. Triacylglycerol was the predominant lipid component in all the organisms examined. Hexadecanoic acid was the main saturated fatty acid; octadecenoic acid and octadecdienoic acid the predominant unsaturated fatty acids. Tetradecanoic, hexadecenoic, octadecanoic and octadectrienoic acids were also detected. The fatty acid distribution pattern appeared unaffected by the nature of substrate and climatic conditions. There is a certain similarity in the fatty acid composition in related species.
TL;DR: A strand segment excised from a network ofPhysarum plasmodium showed no significant rhythmic activities at first, but started rhythmic contraction locally after 10–20 minutes, and was maintained under isotonic as well as isometric conditions.
Abstract: A strand segment excised from a network ofPhysarum plasmodium showed no significant rhythmic activities at first, but started rhythmic contraction locally after 10–20 minutes. To express the development of local rhythms and their synchronizing process in the strand under isotonic conditions, the isolated strand was divided into several subsegments of nearly equal length with small resin particles attached as index markers. Changes in the length of each subsegment were then registered photographically every 10 seconds to obtain an overall view of local contractions. Thus we were able to find the time coordinates of individual sub-segments reaching their maximal length within the span of each corresponding wave representing contraction of the whole strand. Their standard deviation decreased with time becoming as small as 3–5 seconds or 3% of the period of the main waves after 30 minutes. Under isometric conditions, the method using index markers was useful, but we also could demonstrate the synchrony by the fact that the amplitude, period and phase of the tension waves became independent of the length of the strand. Once the contraction-relaxation cycle of each segment in the strand is synchronized, it is maintained under isotonic as well as isometric conditions.
TL;DR: In cells cultured for two days after full growth, dictyosomes began to produce hypertrophied vesicles (HVs) along their five peripheral reagions and fused with each other and with the vacuoles.
Abstract: Transformation of the Golgi apparatus inMicrasterias americana at various stages after full growth and at the earliest stage of cell growth was investigated using an electron microscope. Silver-hexamine staining and the acid phosphatase (ACPase) test were also carried out. In cells cultured for two days after full growth, dictyosomes began to produce hypertrophied vesicles (HVs) along their five peripheral reagions. The HVs contained fibrous material, which was stained by silver-hexamine, and small granules which reacted with ACPase. The HVs were pinched off the dictyosomes and fused with each other and with the vacuoles. In the earliest stage of cell growth, the cisternae of the dictyosomes were stretched in one direction, which modified the shape from circular to elliptical and the dictyosomes curved along the long axis of the ellipse. These curved dictyosomes which produced middle sized vesicles (MVs) from the distal networks, divided into two identical parts along the short axis of the ellipse.
TL;DR: In this article, the authors made a cytochemical study involving enzymic digestions, chemical extractions and specific staining methods was made of the host-parasite interface in downy mildew infected pea plants.
Abstract: A cytochemical study involving enzymic digestions, chemical extractions and specific staining methods was made of the host-parasite interface in downy mildew infected pea plants. Enzymic hydrolysis revealed both the penetration and extrahaustorial matrices to have a proteinaceous component, possibly glycoprotein, while the extrahaustorial matrix had cellulose as an additional constituent. Intense silver proteinate staining of both matrices following a prolonged incubation in thiocarbohydrazide indicated the presence of complex carbohydrates. Carbohydrates were confirmed as constituents of both matrices following the complete suppression of silver staining using the aldehyde blocking agents dimedone and sodium borohydride. Both matrices also exhibited a marked affinity for phosphotungstic acid. Following acetylation a complete elimination of phosphotungstate staining resulted, again indicating carbohydrate as a constituent of both matrices. Digestion of the fungal cell wall using an enzyme which hydrolyses β-1,3-glucans showed that these carbohydrates are important in its construction. However such enzyme treatment did not affect the structural integrity of either the penetration or extrahaustorial matrix. The extrahaustorial membrane exhibited negligible staining with phosphotungstic-chromic acid treatment, while the host plasmalemma showed a positive but variable staining reaction. A very intense staining reaction characterized the fungal plasmalemma after staining with either phosphotungstic-chromic acid, phosphotungstic acid or silver proteinate.
TL;DR: InHoya roots most exodermal cells are elongated and a band of suberin lamellae is formed in all their walls early in development; later on in life, the tertiary wall layers are deposited inside the SUBERIN lamella as mentioned in this paper.
Abstract: InHoya roots most exodermal cells are elongated and a band of suberin lamellae is formed in all their walls early in development; later on carbohydrate tertiary wall layers are deposited inside the suberin lamellae. Some exodermal cells which are restricted to root hair-bearing areas are short and unsuberized but their outer tangential wall is conspicuously thickened. Combined evidence from light microscopy and transmission and scanning electron microscopy reveals the bulk of this cap-formed thickening as a mosaic structure with two different components forming an extensive labyrinth. Irregular masses of a lignified, amorphous substance are separated by radially oriented, tortuous channels containing a very dense, granular-fibrillar material. The innermost wall layer is fibrillar and shows a texture and density similar to the material in the separating channels. The cap contains prominent pits with plasmodesmatal connections between short cells and the epidermis. In mature and non-functional short cells a band of suberin lamellae and eventually tertiary wall layers are deposited.
TL;DR: Suspension culture cells of sycamore (Acer pseudoplatanus L.) and carrot (Daucus carota L.) were frozen to ultralow temperatures either rapidly (⩾ 100 °C s−1), or slowly at controlled rates of 1 or 2 °C min−1 in the presence and in the absence of cryoprotective compounds.
Abstract: Suspension culture cells of sycamore (Acer pseudoplatanus L.) and carrot(Daucus carota L.) were frozen to ultralow temperatures either rapidly (⩾ 100 °C s−1), or slowly at controlled rates of 1 or 2 °C min−1 in the presence and in the absence of cryoprotective compounds. When examined by the conventional freeze-etch procedure, the appearance of the frozen cells correlated closely with that of unfrozen control material examined by thin sectioning after glutaraldehyde-osmium fixation. Cells frozen rapidly or slowly in the absence of cryoprotectants suffered damage by gross intracellular ice formation. Rapid freezing, in the presence of cryoprotectants at levels used in freeze-preservation protocols, caused intracellular ice formation, but the ice crystals size was sufficiently small to avoid compression or rupture of organelles. Cells frozen by the above procedures cannot be recovered in a viable state and this is considered largely to be due to intracellular ice formation which, where not directly damaging during freezing, undergoes disruptive recrystallization during thawing. Slow freezing in the presence of cryoprotectants was associated with a reduction in cell volume by dehydration, reduced intracellular ice formation and good
TL;DR: It was concluded that endoplasm flowing back and forth in a plasmodial strand must carry a factor(s) which coordinates the period and phase of the contraction-relaxation cycle but does not control the amplitude of the cycle.
Abstract: Two separate segments of plasmodial strands (Physarum polycephalum) generally contract and relax with different periods, but if the two are bridged with another small strand segment to make into a single system, the contraction cycles of the two previously separate segments become gradually unified under isometric as well as isotonic conditions. To clarify the possible role of the streaming endoplasm as the information carrier for synchronization, we stopped the streaming between two halves of a single strand either by cutting it or by using the double-chamber method without cutting it. When the endoplasm is prevented from flowing between the two halves of the same continuous system, which had been in good synchrony, their contraction-relaxation rhythms become out of phase with each other. After the endoplasm in the strand is allowed to stream freely again, the synchrony of their cyclic contraction is reestablished. It was concluded that endoplasm flowing back and forth in a plasmodial strand must carry a factor(s) which coordinates the period and phase of the contraction-relaxation cycle but does not control the amplitude of the cycle.
TL;DR: During maturation and senescence of leaves of navel orange (Citrus sinensis L.), total lipids per gram of leaf steadily decline, while chlorophylls, carotonoids and tocopherols increase during maturation, and several large-plastoglobuli in the chloroplasts of mature green leaves.
Abstract: During maturation and senescence of leaves of navel orange (Citrus sinensis L.), total lipids per gram of leaf steadily decline. The decline is attributable to the galactolipid and phospholipid partners, while chlorophylls, carotonoids and tocopherols increase during maturation. The phospholipid/galactolipid ratio declines steadily during maturation and senescence but the monogalactosyldiglyceride/digalactosyldiglyceride ratio remains relatively constant. The phospholipid composition remains relatively constant even though the total phospolipid declines markedly.
TL;DR: The surface of protoplasts showed heavy staining when incubated in lanthanum nitrate or cationized ferritin though not with ruthenium red, and the potential of these surface stains as plasma membrane markers in isolated membrane fractions is discussed.
Abstract: Protoplasts isolated from tobacco leaves showed the development of crystalline bodies in the chloroplasts and osmiophilic droplets in the chloroplasts and cytoplasm. Microbodies stained for catalase with the diaminobenzidine (DAB) reaction although, in the absence of H2O2, mitochondrial cristae also showed a dense reaction. Similar changes and DAB staining were observed in intact leaf cells aged in media similar to that used for protoplast isolation. The cell wall and plasma membrane of fresh leaf cells stained inconsistently with silicotungstic acid (STA). In comparison, the plasma membrane of freshly isolated protoplasts stained very poorly with STA although more intense staining was found in aged protoplasts. The surface of protoplasts showed heavy staining when incubated in lanthanum nitrate or cationized ferritin though not with ruthenium red. The potential of these surface stains as plasma membrane markers in isolated membrane fractions is discussed.
TL;DR: The double and triple-innervated hairs are considered to be mechano-receptors, whereas the sensilla associated with six to ten sensory cells might be Mechano-chemoreceptors.
Abstract: The most frequent type of the hair sensilla on the antennae ofNeomysis integer is investigated by electron microscopic methods. The cellular properties of the sensilla are compared with those of other arthropods in order to detect possible homologies.
TL;DR: Formation of the encystment vesicles and the manner of cleavage are compared with those of other Oomycetes and general aspects ofLagenisma zoosporogenesis are discussed.
Abstract: Zoosporogenesis inLagenisma begins after the final nuclear division by the development of “encystment vesicles” which presumably are derived from Golgi vesicles. The sporangial wall is secreted simultaneously. Initially, the encystment vesicles have an internal coat of fine ribs which becomes a uniform mass during the complicated invagination of the vesicles. When the sporangial wall is complete the protoplast cleaves centripetally by means of narrow “cleavage cisternae” apparently coming from the distal face of the dictyosomes and being detached by interposing ER cisternae. The cleavage cisternae fuse with each other and with the plasmalemma to which they are often parallel. Narrow cytoplasmic compartments are then cut off and swell to become “separation vesicles” which lie between the developing zoospores but later disintegrate. Basal bodies develop from procentrioles after the final nuclear division and elongate into flagella (without participation of a flagellar vesicle) when cleavage is complete. The mastigonemes are formed within the ER, mature within the peripheral elements of the dictyosomes near the flagellar bases and appear to be extruded after the elongation of the flagellum. Structurally, especially in the organization of the flagellar root apparatus, the zoospores resemble primary zoospores of other Oomycetes. They become motile within the zoosporangium but seem to be driven out by means of additional unknown forces.—Formation of the encystment vesicles and the manner of cleavage are compared with those of other Oomycetes and general aspects ofLagenisma zoosporogenesis are discussed.
TL;DR: The functioning of a truncated cone-shaped network of endoplasmic reticulum in the development of the pit connection is described, which occurs in pit connections between cells of the indeterminant axes and also cells of whorled assimilatory branches of limited growth, the pleuridia.
Abstract: A new type of pit connection is described in the fresh water red algaBatrachospermum sirodotii and reported inTuomeya sp. consisting of a doughnut-shaped pit ring with a central pore that is occluded by a rivet-shaped pit plug. This structure occurs in pit connections between cells of the indeterminant axes and also cells of whorled assimilatory branches of limited growth, the pleuridia, but not between axial cells and the basal cells of the pleuridia, the periaxial cells. The pit plug and pit ring ultimately break down in pit connections of the main axis reopening the septal pore to intercellular cytoplasmic connection between vegetative axial cells. A similar breakdown of pit connections may also occur in the pleuridia. The functioning of a truncated cone-shaped network of endoplasmic reticulum in the development of the pit connection is described.