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71.
I examined the ability of frozen-thawed Avena sativa L. coleoptile sections under applied load to extend in response to the calcium chelators ethyleneglycol-bis-(-aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) and 2-[(20bis-[carboxymethyl] amino-5-methylphenoxy)methyl]-6-methoxy-8-bis [carboxymethyl]aminoquinoline (Quin II). Addition of 5 mM EGTA to weakly buffered (0.1 mM, pH 6.2) solutions of 2(N-morpholino) ethanesulfonic acid (Mes) initiated rapid extension and wall acidification. When the buffer strength was increased (e.g. from 20 to 100 mM Mes, pH 6.2) EGTA did not initiate extension nor did it cause wall acidification. At 5 mM Quin II failed to stimulate cell extension or wall acidification at all buffer molarities tested (0.1 to 100 mM Mes). Both chelators rapidly and effectively removed Ca2+ from Avena sections. These data indicate that Ca2+ chelation per se does not result in loosening of Avena cells walls. Rather, EGTA promotes wall extension indirectly via wall acidification.Abbreviations EGTA
ethyleneglycol-bis-(-aminoethylether)-N,N,N,N-tetraacetic acid
- Quin II
2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis(carboxymethyl)aminoquinoline
- Mes
2(N-morpholino)ethanesulfonic acid 相似文献
72.
Both thick- and thin-walled sieve tubes in leaf-blade veins of Hordeum vulgare L. exhibit a distinct, electron-opaque inner wall layer after fixation in glutaraldehyde-osmium tetroxide and staining with uranyl acetate and lead citrate. This inner wall layer is thickest at the sieve plates and lateral sieve areas where it is permeated by a labyrinth of tubules formed by the plasmalemma. Along the lateral walls between sieve areas the inner wall layer apparently is penetrated by numerous microvilli-like evaginations of the plasmalemma, giving the cell wall-plasmalemma interface the appearance of a brush border. It is suggested that a similar brush-border-like structure may occur at the cell wall-plasmalemma interface of sieve elements in a wide variety of vascular plants.Abbreviation ER
endoplasmic reticulum 相似文献
73.
Summary Cell wall regeneration around protoplasts from Black Mexican Sweet corn suspension cells has been observed using scanning electron microscopy. A coherent array of cellulose microfibrils can be seen around protoplasts two hours after they have been isolated. This array does not form in the presence of 15 mg/l Congo Red. The frequency and electrical resistance of seals made between patch clamp pipettes and the plasmalemma around corn protoplasts is not significantly affected by the presence or absence of these fibrils (p0=0.75); it remains relatively low. Some single channel records from BMS corn protoplasts are shown. 相似文献
74.
Summary Uniseriate filaments of the freshwater red algaCompsopogon coeruleus were examined by transmission electron microscopy for details of vegetative organization and cell division with the goal of providing useful taxonomic characters. Each cell's single, complex chloroplast contains a peripheral encircling thylakoid, and unlike the vast majority of red algae, the cis-regions of dictyosomes are not consistently juxtaposed with mitochondria. These subcellular features, which are present in all examined genera in theCompsopogonales, Erythropeltidales, andRhodochaetales, along with certain unique reproductive characteristics, unify these three orders. During mitosis in uncorticated axial cells, a small, ring-shaped nucleus associated organelle (NAO) is located at each division pole, an intranuclear spindle comes to a moderately acute focus at the flattened, fenestrated metaphase-anaphase division poles and perinuclear ER partially encloses dividing nuclei, including a well-developed interzonal midpiece. The cleavage furrow penetrates the large, central vacuolar region to separate daughter nuclei. These cell division features most closely resemble the pattern described for the orderCeramiales. Our observations of vegetative and dividing cells ofC. coeruleus supplement the growing volume of evidence in favour of uniting all red algae into a single class without subclass designations.Abbreviations ER
endoplasmic reticulum
- IZM
interzonal midpiece
- MT
microtubule
- MTOC
microtubule organizing center
- NAO
nucleus associated organelle
- NE
nuclear envelope
- PER
perinuclear endoplasmic reticulum 相似文献
75.
Dr. S. Forsgren 《Cell and tissue research》1989,256(1):125-135
Summary Recent studies have accomplished the establishment of a collagenous fiber-fringe matrix upon dental root surfaces in vitro. The present study was undertaken to follow the development of such a matrix in vitro and to test the possible effects of root surface treatments upon this matrix. Periodontal ligament cells, 0.1 to 0.2-mm thick dental root discs, and alveolar bone cells were derived after extraction from four partially erupted third molars and the accompanying interradicular bony septa of 1 male patient. Autologous serum was obtained by venipuncture. Cultures were initiated by delivering a 1-ml suspension of 50000 tritiated thymidine-labeled periodontal ligament cells and 50000 alveolar bone cells onto each of 42 culture sets. The following day, demineralized or non-demineralized root discs treated with autologous serum, fibronectin or complete medium were placed in pairs, separated by a 0.1–1.0 mm gap, upon the initial cell layer. Representative cultures were terminated after 2, 3, 4, 5 and 6 weeks, and processed for light- and electron microscopy, morphometric analysis and autoradiography. An outstanding feature of the early cultures (2, 3 and 4 weeks) was a patchwise, random distribution of matrix making a precise developmental study impossible, although collagen fibrils were produced within the first 2 weeks. Some 3-week cultures already demonstrated a mature fiber-fringe characterized electron-microscopically as oriented, densely packed collagen fibrils closely abutting the cementum-lined root discs. The treatments (including autologous serum) used in this study had no appreciable morphologic or morphometric effect upon the fiber-fringe formed. Because none of the cultures in the present or past studies have demonstrated a true cementoid matrix, this model may not be suitable for the in-vitro study of cementum formation. 相似文献
76.
Yaffa Mizrachi Peter I. Lelkes Richard L. Ornberg Gertrude Goping Harvey B. Pollard 《Cell and tissue research》1989,256(2):365-372
Summary Chromaffin cells in the adrenal medulla are found in close proximity to capillary endothelial cells, thereby forming the classical endocrine complex. To examine the possible chemical basis of their interaction in more detail, we have grown bovine adrenal medullary endothelial (BAME) cells in monolayer cultures and added to them pheochromocytoma (PC12) cells, a chromaffin tumor cell line of rats. The PC12 cells were chosen because of the similarities they share with adrenal medullary chromaffin cells. PC12 cells rapidly attached to BAME cells cultures, their rate of adhesion being significantly enhanced over binding of PC12 cells to either uncoated plates or to monolayers of unrelated cell cultures. Consistent with this observation, we noted that the extracellular matrix (ECM) derived from the BAME cells did not enhance PC12 cell adhesion and did not promote neurite sprouting as previously described for ECM derived from corneal endothelial cells. The specific adhesion between PC12 and BAME cells could be abolished by cell surface extracts derived from these two cells but not by extracts derived from unrelated cell types. This activity was heat-labile, sensitive to trypsin and, to a lesser extent, to neuraminidase. We therefore conclude that PC12 cells may interact with BAME cells by specific proteinaceous adhesive factors associated with their plasma membranes. These interactions might represent the formative role of cell-cell contacts in the organization of the developing adrenal gland.Abbreviations
BAME
bovine adrenal medullary endothelial cells
-
DMEM
Dulbecco's modified essential medium
-
ECM
extracellular matrix
-
EMEM
Eagle's modified essential medium
-
FCS
fetal calf serum
-
PBS
phosphate-buffered saline
-
PC12
rat pheochromocytoma cells 相似文献
77.
By using sodium thioglycolate to dissolve the high amount of excreted stalk material in axenic cultures of the chemolithoautotrophic iron bacterium Gallionella ferruginea, the ultrastructure of Gallionella cells from pure cell suspensions could be studied without any loss of viability or disturbance by dense ferric stalk fibers, and compared with Thiobacillus ferrooxidans, also grown chemolithoautotrophically with ferrous iron as energy source. Both organisms were chemically fixed or freeze-etched. Particular structural differences between these iron-bacteria could be ascertained. G. ferruginea possesses intracytoplasmic membranes and soluble d-ribulose-1,5-bisphosphate-carboxylase, whereas T. ferrooxidans contains carboxysomes but no intracytoplasmic membranes; Gallionella forms poly--hydroxybutyrate and glycogen as storage material; T. ferrooxidans produces only glycogen. Both organisms also differ from each other with respect to the freeze fracture behaviour of the cell envelope layers. Whereas the cells of T. ferrooxidans exhibit a characteristic double cleavage, exposing the plasmic fracture face and exoplasmic fracture face of the outer membrane and cytoplasmic membrane, the exceptionally thin multilayered cell envelope of G. ferruginea revealed a particularly intimate association between the layers, resulting in a visualisation of the supramolecular organisation of only the inner fracture face of the cytoplasmic membrane. The results are discussed predominantly in relation to the extremely distinct environments of both organisms. 相似文献
78.
It is generally accepted that during fast growth of Escherichia coli, the time (D) between the end of a round of DNA replication and cell division is constant. This concept is not consistent with the fact that average cell mass of a culture is an exponential function of the growth rate, if it is also accepted that average cell mass per origin of DNA replication (Mi) changes with growth rate and negative exponential cell age distribution is taken into account. Data obtained from cell composition analysis of E. coli OV-2 have shown that not only (Mi) but also D varied with growth rate at generation times () between 54 and 30 min. E. coli OV-2 is a thymine auxotroph in which the replication time (C) can be lengthened, without inducing changes in , by growth with limiting amounts of thymine. This property has been used to study the relationship between cell size and division from cell composition measurements during growth with different amounts of thymine. When C increased, average cell mass at the end of a round of DNA replication also increased while D decreased, but only the time lapse (d) between the end of a replication round and cell constriction initiation appeared to be affected because the constriction period remained fairly constant. We propose that the rate at which cells proceed to constriction initiation from the end of replication is regulated by cell mass at this event, big cells having shorter d times than small cells.Abbreviations OD450 and OD630
Optical density at a given wavelength in nm
Dedicated to Dr. John Ingraham to honor him for his many contributions to Science 相似文献
79.
Paul G. Layer Regina Alber Patrick Mansky Günter Vollmer Elmar Willbold 《Cell and tissue research》1990,259(2):187-198
Summary We report here that similar to E6-chicken retinal cells, dissociated cells from 5.5-day-old (E5.5) quail retinae reaggregate in rotary culture, multiply about tenfold and reestablish histotypical areas. These cellular aggregates include all nuclear layers either with inversed or correct laminar polarity, depending on the local origin of the cells (called rosetted and laminar in-vitro-retinae (IVR), respectively; Layer and Willbold 1989). In combined cultures, chick and quail cells are evenly mixed only during the first two days of culture. Along with the assembly of single cells into rosettes and then into discrete laminae, sectors of chick and quail cells begin to segregate. They are delineated by borders running radially through all three nuclear layers. Thus, interspecies migration of cells at this advanced stage of differentiation is strongly inhibited. Concomitant with this segregation, coherent radial columns spanning all three layers but containing cells from either species only, can be traced histologically. We conclude that a weak segregation of chick and quail retinal cells takes place already at the single cell level, but that the permanent segregation of entire tissue parts must be due to clonal cellular proliferation within the IVR in conjunction with some developmental-structural mechanism retaining clonal progenies within a columnar order.Abbreviations
ECM
extracellular matrix
-
E5.5
days of embryonic age
-
GCL
ganglion cell layer
-
GC's
ganglion cells
-
i.c.
in culture
-
INL
inner nuclear layer
- rosetted in-vitro-retina
retinal cell organoid aggregated from single cells of the central retina
-
IPL
inner plexiform layer
-
MRE
marginal retinal epithelium
-
ONL
outer nuclear layer
-
OPL
outer plexiform layer
-
OS
ora serrate
-
PR
photoreceptor cell
- laminated in-vitro-retina
fully laminated retinal cellorganoid resembling an E15-retina aggregated from cells of the eye periphery including RPE
-
RPE
retinal pigment epithelium 相似文献
80.
Effects of substrata on the polarization of bovine endometrial epithelial cells in vitro 总被引:2,自引:0,他引:2
Summary Epithelial-cell function requires cellular polarity in which apical membrane surfaces have unique characteristics and cellular organelles are stratified. Physiological investigations of endometrial, epithelial cells would be enhanced greatly by the ability of a method to polarize cells in culture. This study investigates the effects of different substrata on polarization of cultured bovine endometrial epithelial cells. Fetal bovine endometrial epithelial-cell lines were developed from explant outgrowth. Epithelial monolayers were subcultured onto amniotic membranes, Millicell-HA membranes, or Millicell-CM membranes coated with rat-tail collagen, Matrigel, laminin, Vitrogen,or fibronectin. Cultures on these substrata were maintained at the air/liquid interface. Cells grown on either collagen-coated or uncoated Milli-cell membranes also were maintained submerged in medium. Excellent polarized morphology was attained in cultures grown at the air/liquid interface on amniotic membranes and rat-tail collagen-coated membranes. Lectin-binding patterns, to apical membranes of polarized epithelial cell cultures paralleled patterns of binding to bovine endometrial surfaces in vivo. Cultures on rat-tail collagen were maintained for several weeks. These methods provide a valuable system for studying the endometrium in vitro. 相似文献