bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoradiographs of Pollen Tube Nuclei with Calcium-45
Authors: Steffensen Dale , Bergeron John A. 
Published: May 2004

Autoradiography with Ca45 has been used to obtain information about the relation between calcium and chromosomes. Labelled pollen from the Easter lily, Lilium longiflorum, was allowed to develop into pollen tubes between 5 and 6 cm. long in the styles of non-radioactive flowers. All of the nuclei, namely the tube nucleus and the two sperm nuclei, retain Ca45 after this period of growth and development.
Since the two sperm nuclei have formed during this interval by the mitotic division of the generative nucleus and growth of the tube has occurred under the influence of the tube nucleus, it is inferred that the calcium was bound in a stable nuclear component, the chromosomes.
A Neoplastic Connective Tissue Mast Cell Capable of Continuous Growth In Tissue Culture
Authors: Williams William J. , Larson Edna , Phillips Theodore L. 
Published: May 2004

A neoplastic connective tissue mast cell from a dog mast cell sarcoma has been grown in tissue culture for 50 passages over a period of 2 years. The cells were grown as monolayer cultures in glass bottles, using Eagle's basal medium fortified with calf serum. The cultures were contaminated with an Alkaligenes sp. for 10 months but finally were sterilized bacteriologically by treatment with specific antiserum combined with antibiotics.
The cells grow in a fibroblastic pattern, and contain mitochondria, mast cell granules, and lipid granules or droplets. The mast cell granules stain basophilic with Giemsa's stain and metachromatically with azure A or toluidine blue. They also stain with Sudan black B and with periodic acid-Schiff stain. The interphase nuclei are vesicular, contain from 1 to 20 nucleoli, and frequently show bizarre outlines. Multinucleate cells are often seen, as are mitotic figures. Extracellular fibrous material occurs in all cultures and apparently originates from the cell surface. This material does not have the structure of connective tissue fibers and has not been identified.
The cells develop an increased number of metachromatic granules when grown in medium containing heparin and an increased number of sudanophilic granules when grown in medium containing stearic acid. Only small amounts of histamine were present in the tumor from which this cell line was derived and in the cells grown in tissue culture.
Effect of Thioacetamide on Rat Liver Regeneration
Authors: Kleinfeld R. G. , von Haam E. 
Published: May 2004

The effect of thioacetamide on dividing cells of regenerating rat liver has been studied. Rats were given daily subcutaneous injections of thioacetamide as a 1 per cent solution at a dosage of 5 mg./100 gm. body weight for 7 to 10 days, subjected to partial hepatectomy, and sacrificed 28 to 31 hours later.
Thioacetamide treatment results in striking increases in the nuclear ribonucleoproteins of the liver cell without affecting the mitotic rate during regeneration (14). During mitosis, RNA-containing particles were seen within the spindle and coating the contracted chromosomes from prophase through metaphase or early anaphase. At telophase, prior to the reconstruction of the nuclear membrane, fine RNA-containing granules appeared within the compact chromosomal groups. These coalesced to form nucleoli corresponding in number to the number of nucleolar organizer regions. The nuclei and nucleoli showed a rapid increase in size during the reconstruction period when compared with corresponding figures of the control liver samples.
Electron micrographs of interphase nucleoli indicated a similar basic granular structure in both drug-treated and control animals.
The question is raised as to whether the increased nucleolar material merely made visible some of the nucleolar-chromosomal associations that normally occur in mitosis, or whether thioacetamide directly affects the synthetic activity of the contracted mitotic chromosomes.
Entwicklung und Struktur der Proplastiden
Authors: Mühlethaler Kurt , Frey-Wyssling Albert 
Published: May 2004

In this study the proplastid development in embryonic cells is described for the apical meristem of Elodea canadensis, embryo sacs from Lilies, and Begonia leaf buds. The formation of these cell organelles originates with submicroscopical particles which consist of a homogeneous stroma with a surrounding double membrane. When these proplastids reach an average size of 1 µ, the inner layer of the membrane begins to invaginate into the stroma. This process is comparable to tubuli formation in mitochondria.
Under growth conditions with sufficient exposure to light, the development of the grana and stroma lamellae proceeds without interruption. If the plants are kept in the dark, small vesicles are formed which accumulate in the prolamellar body of the proplastids. After illumination these elementary vesicles merge to form membranes which evolve into grana and stroma lamellae. The structural similarity of the early proplastid stages with the mitochondria seems to indicate that there exists some phylogenetic relationship between the two cell organelles.
MIGRATION OF GLYCOPROTEIN FROM THE GOLGI APPARATUS TO THE SURFACE OF VARIOUS CELL TYPES AS SHOWN BY RADIOAUTOGRAPHY AFTER LABELED FUCOSE INJECTION INTO RATS
Authors: Bennett Gary , Leblond C. P. , Haddad Antonio 
Published: May 2004

A single intravenous injection of L-[3H]fucose, a specific glycoprotein precursor, was given to young 35–45 g rats which were sacrificed at times varying between 2 min and 30 h later. Radioautography of over 50 cell types, including renewing and nonrenewing cells, was carried out for light and electron microscope study.
At early time intervals (2–10 min after injection), light microscope radioautography showed a reaction over nearly all cells investigated in the form of a discrete clump of silver grains over the Golgi region. This reaction varied in intensity and duration from cell type to cell type. Electron microscope radioautographs of duodenal villus columnar cells and kidney proximal and distal tubule cells at early time intervals revealed that the silver grains were restricted to Golgi saccules. These observations are interpreted to mean that glycoproteins undergoing synthesis incorporate fucose in the saccules of the Golgi apparatus. Since fucose occurs as a terminal residue in the carbohydrate side chains of glycoproteins, the Golgi saccules would be the site of completion of synthesis of these side chains.
At later time intervals, light and electron microscope radioautography demonstrated a decrease in the reaction intensity of the Golgi region, while reactions appeared over other parts of the cells: lysosomes, secretory material, and plasma membrane. The intensity of the reactions observed over the plasma membrane varied considerably in various cell types; furthermore the reactions were restricted to the apical surface in some types, but extended to the whole surface in others.
Since the plasma membrane is covered by a "cell coat" composed of the carbohydrate-rich portions of membrane glycoproteins, it is concluded that newly formed glycoproteins, after acquiring fucose in the Golgi apparatus, migrate to the cell surface to contribute to the cell coat. This contribution implies turnover of cell coat glycoproteins, at least in nonrenewing cell types, such as those of kidney tubules. In the young cells of renewing populations, e.g. those of gastro-intestinal epithelia, the new glycoproteins seem to contribute to the growth as well as the turnover of the cell coat. The differences in reactivity among different cell types and cell surfaces imply considerable differences in the turnover rates of the cell coats.
SYNTHESIS, MIGRATION, AND RELEASE OF PRECURSOR COLLAGEN BY ODONTOBLASTS AS VISUALIZED BY RADIOAUTOGRAPHY AFTER [3H]PROLINE ADMINISTRATION
Authors: Weinstock Melvyn , Leblond C. P. 
Published: May 2004

The elaboration of dentin collagen precursors by the odontoblasts in the incisor teeth of 30–40-g rats was investigated by electron microscopy, histochemistry, and radioautography after intravenous injection of tritium-labeled proline.
At 2 min after injection, when the labeling of blood proline was high, radioactivity was restricted to the rough endoplasmic reticulum, indicating that it is the site of synthesis of the polypeptide precursors of collagen, the pro-alpha chains.
At 10 min, when the labeling of blood proline had already declined, radioactivity was observed in spherical portions of Golgi saccules containing entangled threads, and, at 20 min, radioactivity appeared in cylindrical portions containing aggregates of parallel threads. The parallel threads measured 280–350 nm in length and stained with the low pH-phosphotungstic acid technique for carbohydrate and with the silver methenamine technique for aldehydes (as did extracellular collagen fibrils). The passage of label from spherical to cylindrical Golgi portions is associated with the reorganization of entangled into parallel threads, which is interpreted as the packing of procollagen molecules.
Between 20 and 30 min, prosecretory and secretory granules respectively became labeled. These results indicate that the cylindrical portions of Golgi saccules transform into prosecretory and subsequently into secretory granules. Within these granules, the parallel threads, believed to be procollagen molecules, are transported to the odontoblast process.
At 90 min and 4 h after injection, label was present in predentin, indicating that the labeled content of secretory granules had been released into predentin. This occurred by exocytosis as evidenced by the presence of secretory granules in fusion with the plasmalemma of the odontoblast process.
It is proposed that pro-alpha chains give rise to procollagen molecules which assemble into parallel aggregates in the Golgi apparatus. Procollagen molecules are then transported within secretory granules to the odontoblast process and released by exocytosis. In predentin procollagen molecules would give rise to tropocollagen molecules, which would then polymerize into collagen fibrils.
RNA SYNTHESIS IN THE MOUSE OOCYTE
Authors: Moore G. P. M. , Lintern-Moore Sue , Peters Hannah , Faber M. 
Published: May 2004

RNA synthesis in the oocyte and granulosa cell nuclei of growing follicles has been studied in the mouse ovary. The RNA precursor [3H]uridine was administered intraperitoneally to adult mice and the amount of label incorporated into ovarian RNA was quantitated autoradiographically using grain-counting procedures. Uridine incorporation into the nucleus is low in oocytes of small, resting follicles but increases during follicle growth and reaches a peak prior to the beginning of antrum formation. Thereafter uptake rapidly declines and is very low in the oocytes of maturing follicles. Uridine incorporation into granulosa cell nuclei, in contrast to that found in the oocyte, increases gradually during most of the period of follicle growth.
Qualitative studies of the activity of endogenous, DNA-dependent RNA polymerases have also been made in fixed oocytes isolated from follicles at different stages of growth. Polymerase activity is demonstrable in the nucleolus and nucleoplasm of oocytes from growing follicles, but is absent from maturing oocytes of large follicles.
EFFECTS OF SERUM ON MEMBRANE TRANSPORT
Authors: Strauss Phyllis R. 
Published: May 2004

When monolayers of freshly obtained rabbit lung macrophages are exposed to the nucleoside analogue, showdomycin (sho), adenosine transport, measured over a 45 s interval, is irreversibly inhibited. Low doses of the drug or short periods of exposure, however, do not result in decreased transport, while higher concentrations or longer exposures result in exponential decline. The initial lag is not due to a long reaction time of sho with the transport carrier or to nonspecific sites absorbing the drug.
Previously it was shown that preincubation of monolayers with normal rabbit serum (NRS) results in increased adenosine transport. When monolayers are first exposed to sho so as to inhibit transport to varying degrees and then incubated with NRS, transport is increased over the inhibited level. Several experiments make it unlikely that serum removes the drug from the cell surface in a nonspecific fashion. Moreover, serum given before, during, or after sho alters the dose response curve so that no shoulder is seen. One way to explain these results makes use of target theory: the adenosine transport system could be comprised mainly of "coupled" or "clustered" sites of which only one is active at any time as well as "hidden" sites which are inactive. When a site in a group is irreversibly inactivated by sho, another in the group becomes activated. Serum might activate or uncouple all sites and also cause the appearance of hidden sites, which previously neither transported nor bound sho.
MONOLAYER CULTURES DERIVED FROM NEONATAL HAMSTER PANCREAS
Authors: Scheid C. R. , Macchi I. A. 
Published: May 2004

Cells derived by trypsinization of neonatal golden hamster pancreas were cultured in modified Eagle's medium for 120 h in the presence of glucose (0.8 mg/ml) and for an additional 48 h in medium containing glucose (0.8 or 3.1 mg/ml) or tolbutamide (1,000 µg/ml) plus glucose (0.8 mg/ml). At day 7, cultures were stained differentially for light microscopy or examined by electron microscopy. Immunoreactive insulin (IRI) and immunoreactive glucagon (IRG) in the culture medium were measured by standard immunoassay procedures.
Staining properties and ultrastructural appearance of cultured cells were comparable to those of the intact neonatal hamster pancreas. Cultures consisted predominantly of cells possessing aldehyde fuchsin positive (AF+) cytoplasmic granules resembling ultrastructurally those of the intact neonatal pancreatic beta cells and additionally, those of fibroblastoid, acinar, acino-insular, and aldehyde fuchsin negative (AF-) argyrophilic cells. IRI release rate by the cultured cells was increased in the presence of elevated glucose or tolbutamide which paralleled the loss of AF+ granulation, but IRG release rate was suppressed by elevated glucose concentration.
These findings indicate that these monolayer cultures consist of most of the cell types occurring in the neonatal pancreas, including endocrinologically competent islet cells.
EFFECTS OF COLCHICINE, CYTOCHALASIN B, AND 2-DEOXYGLUCOSE ON THE TOPOGRAPHICAL ORGANIZATION OF SURFACE-BOUND CONCANAVALIN A IN NORMAL AND TRANSFORMED FIBROBLASTS
Authors: Ukena Thomas E. , Borysenko Joan Z. , Karnovsky Morris J. , Berlin Richard D. 
Published: May 2004

The distribution of surface-bound concanavalin A on the membranes of 3T3, and simian virus 40-transformed 3T3 cultured mouse fibroblasts was examined using a shadow-cast replica technique with a hemocyanin marker.
When cells were prefixed in paraformaldehyde, the binding site distribution was always random on both cell types. On the other hand, labeling of transformed cells with concanavalin A (Con A) and hemocyanin at 37°C resulted in the organization of Con A binding sites (CABS) into clusters (primary organization) which were not present on the pseudopodia and other peripheral areas of the membrane (secondary organization). Treatment of transformed cells with colchicine, cytochalasin B, or 2-deoxyglucose did not alter the inherent random distribution of binding sites as determined by fixation before labeling. However, these drugs produced marked changes in the secondary (but not the primary) organization of CABS on transformed cells labeled at 37°C. Colchicine treatment resulted in the formation of a caplike aggregation of binding site clusters near the center of the cell, whereas cytochalasin B and 2-deoxyglucose led to the formation of patches of CABS over the entire membrane, eliminating the inward displacement of patches observed on untreated cells. The distribution of bound Con A on normal cells (3T3) at 37°C was always random, in both control and drug-treated preparations.
Pretreatment of cells with Con A enhanced the effect of colchicine on cell morphology, but inhibited the morphological effects of cytochalasin B. The mechanisms that determine receptor movement and disposition are discussed.
CALCIUM PHOSPHATE GRANULES IN THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS
Authors: Becker Gerald L. , Chen Chung-Ho , Greenawalt John W. , Lehninger Albert L. 
Published: May 2004

The hepatopancreas of the adult male blue crab Callinectes sapidus in intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 µg-atoms per g wet tissue, respectively, accounting for over 10% of the tissue dry weight. Electron microscopy of the intact tissue showed three qualitatively different granular structures having electron densities suggestive of high mineral content. After fractionation of the tissue using centrifugal techniques, almost 95% of the total mineral was found to reside in a heavy, nonmitochondrial particulate fraction(s). The bulk of the low-speed pellet consisted of relatively dense, roughly spherical granules 1–5 µm in diameter, which could be considerably purified by repeated suspension in water and low-speed sedimentation. In the electron microscope the isolated granules appeared basically similar to one of the three characteristic types of electron-dense granules seen in the intact tissue. Although the freshly isolated granules lost approximately 50% of their wet weight when dried at 105°C, only 10% more was lost upon dry ashing at 450°C, suggesting a fairly low content of organic material. Chemical analysis revealed calcium, magnesium, and inorganic phosphate at 5.7, 2.1, and 4.4 µg-atoms per mg dried granules, respectively, accounting for 69% of the dry weight of the fraction. By specific enzymatic assays, the freshly isolated granules were found to contain ATP, ADP, and AMP at levels of 0.13, 0.03, and 0.01 µmol/mg, or 8% of their total dry weight. The remainder of the total phosphorus contributed an additional 3%, whereas carbonate, citrate, oxalate, and protein each constituted no more than 1%.
The mineral granules of the crab hepatopancreas appear to function as storage forms of calcium and phosphate during the intermolt period. This tissue appears promising as a model for study of the cellular events associated with biological calcification, since conventional biochemical techniques can be employed. Furthermore, the major mineralized component of the tissue can be obtained in large amounts for direct study by a simple fractionation procedure.
ELECTRON MICROSCOPE AND EXPERIMENTAL INVESTIGATIONS OF THE NEUROFILAMENTOUS NETWORK IN DEITERS' NEURONS
Authors: Metuzals J. , Mushynski W. E. 
Published: May 2004

The assembly of filamentous elements and their relations to the plasma membrane and to the nuclear pores have been studied in Deiters' neurons of rabbit brain. Electron microscopy of thin sections and of ectoplasm spread preparations have been integrated with physicochemical experiments and differential interference microscopy of freshly isolated cells. A neurofilamentous network extends as a continuous, three-dimensional, semilattice structure throughout the ectoplasm, the "plasma roads," and the perinuclear zone of the perikaryon. This space network consists of ∼90-Å wide neurofilaments arranged in fascicles which are interconnected by an exchange of neurofilaments. The neurofilaments consist of intercoiled ∼20-Å wide unit-filaments and are associated through cross-associating filaments with other neurofilaments of the fascicle and with microfilaments. The ∼20–50-Å wide microfilaments display intimate associations with the plasma membrane and with the nuclear pores. Electron microscopy of thin sections from glycerinated and heavy meromyosin-treated Deiters' neurons shows that actin-like filaments are present in the pre- and postsynaptic regions of synapses terminating on these neurons.
It is proposed that the neurofilamentous space network serves a transducing function by linking plasma membrane activities with the genetic machinery of the neuron.
ULTRASTRUCTURAL DISTRIBUTION OF CELL SURFACE ANTIGENS IN AVIAN TUMOR VIRUS-INFECTED CHICK EMBRYO FIBROBLASTS
Authors: Phillips E. R. , Perdue J. F. 
Published: May 2004

The distribution of neoantigens in the surface membrane of avian tumor virus-infected chicken embryo fibroblasts was examined on carbon replicas of cell cultures using hemocyanin-labeled antibody. New determinants appearing on the cell surface of virally infected but not transformed cells are thought to be common with components of the viral envelope. These antigens were found to exist in a diffuse, random array on the dorsal cell surface, with a denser accumulation along the cell processes. In living cells, surface antigens are capable of several types of redistribution when activated by reaction with antibody. Leukosis virus-infected (non-transformed) cells showed two apparently independent modes of redistribution: a relocation of some antibody-related sites to the cell margin; or an involvement of essentially all sites in randomly dispersed aggregates. Viral antigenic sites on sarcoma virus-infected (transformed) cells, reacted with antibody, were able to produce weak marginal relocation; but revealed a more striking tendency to migrate to some central location. The centripetal coalescence thus formed resembles the "cap" noted in other systems. Prior aggregation into "patches" may not be a prerequisite for such cap formation.
Tumor-specific surface antigen detection and mapping was attempted by this technique, but results were equivocal. An antigen possibly characteristic of rapidly dividing cells occurred in a sparse, diffuse fashion over the surface of morphologically distinct "round" cells.
DIFFERENTIAL LOCALIZATION OF CELL SURFACE AND SECRETORY COMPONENTS IN RAT INTESTINAL EPITHELIUM BY USE OF LECTINS
Authors: Etzler Marilynn E. , Branstrator Margaret L. 
Published: May 2004

Sections through various levels of small intestine from adult male rats were examined by fluorescence microscopy after treatment with fluorescein isothiocyanate-labeled lectins from Dolichos biflorus, Lotus tetragonolobus, Ricinus communis, and Triticum vulgare (wheat germ). The latter three lectins reacted with the microvillar portion of the epithelial cells lining the crypts and villi in sections of intestine adjacent to the pylorus. This pattern of reactivity was sharply altered along the first 15 cm of intestine so that in sections distal to this point the luminal surfaces of only those epithelial cells in the crypts and at the base of the villi reacted with the L. tetragonolobus and R. communis lectins, whereas the wheat germ lectin reacted with the surfaces of the cells lining the villi. In sections from the distal end of the small intestine, all three lectins reacted with the surfaces of cells only at the base of the villi and in the crypts.
These results show a difference in surface components in cells at various portions on the villi and the dependence of these differences on the region of intestine. The D. biflorus lectin reacted with approximately 25% of the goblet cells at each level of intestine studied whereas the reactivities of the goblet cells with the other three lectins were dependent upon the region of intestine.