bluuebunny/crossref_metadata_2025 huggingface dataset:
RESPONSES OF CELLS TO pH CHANGES IN THE MEDIUM
Authors: Taylor A. Cecil
Published: May 2004

Studies were made with time-lapse motion pictures of the reactions of cells in culture to changes in their environment. The concentrations of H+, HCO3-and CO2 in the medium were altered in such a way that each, in turn, could be maintained constant while the others were varied. Observations were made on the shape of the cells, their activity, and their relation to the substratum. Characteristic reversible changes in the cells were observed whenever environmental pH was altered. Elevation of the pH accelerated cell movements and caused contraction of the cytoplasm, while lowering of the pH retarded and eventually stopped all cell activity, causing apparent gelation of the protoplasm. These responses did not occur when HCO3- and CO2 were varied without changing the pH. It is suggested that local pH changes in the micro-environment of a cell's surface may be a significant factor in controlling cell behavior in culture and in vivo.
THE MITOTIC APPARATUS
Authors: Kane R. E.
Published: May 2004

The fine structure of the mitotic apparatus isolated from the sea urchin egg has been investigated. The isolation was accomplished by lysis of metaphase eggs in a 1 M solution of hexanediol, buffered at pH 6. The fine structure of the isolated apparatus was studied after fixation with osmium tetroxide directly in the isolation medium. The spindle is composed of fine fibrils, approximately 20 mµ in diameter, which appear tubular. Similar fibrils, radially oriented, are found in the aster. If the isolated mitotic apparatus is exposed to water at pH 6 before fixation, the structure is considerably modified. The most pronounced effects are an increase in the number of large membrane-bounded vesicles and in the amount of free granular material present. The conditions necessary for the fixation of the mitotic apparatus in dividing cells are discussed in the light of these observations on the isolated unit.
CHLOROPLAST DEVELOPMENT IN OCHROMONAS DANICA
Authors: Gibbs Sarah P.
Published: May 2004

When dark-grown cells of Ochromonas danica are placed in the light, the amount of chlorophyll a per cell increases 82-fold; the content of carotenoid pigment, 24-fold. Concomitantly with this increase in chlorophyll and carotenoid pigment, the small proplastid of dark-grown cells develops into a large lamellate chloroplast. During the first 12 hours in the light, vesicles appear within the loose clusters of dense chloroplast granules, enlarge, align themselves into rows (plates in three dimensions), and fuse into discs. Double discs may form from the more or less simultaneous fusion of two adjacent plates of vesicles or by the addition of vesicles to an already formed single disc. Three-disc bands arise by the addition of a disc to an already formed two-disc band through the approach and fusion of more vesicles. After 24 hours in the light, most of the chloroplast bands contain three discs, but the chloroplasts are still small. After 48 hours in the light, almost all the cells contain full-sized chloroplasts with a full complement of three-disc bands. However, at this time the amount of chlorophyll a and carotenoid pigment is only one-half of maximum. During the next 3 days in the light, as the number of chlorophyll and carotenoid molecules per chloroplast approximately doubles, there is a compression of the discs in each band (from 180 to 130 A) and a precise alignment of their membranes. Changes also occur in the nucleus when dark-grown cells are placed in the light. There is an increase in the number of small nucleolar bodies, many of which lie directly against the nuclear envelope, and in a few cells a dense mass of granules is seen between the two membranes of the nuclear envelope.
FINE STRUCTURAL LOCALIZATION OF ADENOSINETRIPHOSPHATASE ACTIVITY IN HEART MUSCLE MYOFIBRILS
Authors: Tice Lois W. , Barrnett Russell J.
Published: May 2004

Activity of myofibrillar adenosinetriphosphatase was demonstrated histochemically at a fine structural level in isolated, unfixed or hydroxyadipaldehyde-fixed cardiac myofibrils in the rat, using a lead precipitation technique and either Ca++ or Mg++ as activating ion. Activity in relaxed myofibrils was found in the A band, but not the H, I, or Z bands. Deposits of final product frequently exhibited an axial periodicity of near 365 A, and bore a close relationship to filaments within the A band. Several patterns of distribution occurred in contracted myofibrils. In myofibrils which had shortened to the point of disappearance of the I band, final product was distributed throughout the sarcomere, except for the unreactive Z band. A second type of distribution occurred in strongly contracted fibers in which there was intensification of activity in the center of the sarcomere. These findings are discussed in the light of the recent morphological evidence and it is suggested that the distribution of final product is consistent with localization of enzyme activity to the cross-bridges between the thick and thin filaments.
STUDIES ON PROTEIN UPTAKE BY ISOLATED TUMOR CELLS
Authors: Ryser H. , Aub J. C. , Caulfield J. B.
Published: May 2004

Surface adsorption is studied in some detail because it is believed to be a major artifact in measurements of protein uptake by mammalian cells. Adsorption increases linearly with the I131-albumin concentration between 0.001 and 300 mg/ml. After short exposure to 300 mg/ml and two cell washings, the adsorption amounts to 38 mg albumin per gm cell proteins. Further washings remove 80 per cent of this value, leaving a small irreversibly bound residue. At equilibrium, adsorbed albumin can be labeled by a simple albumin exchange. This labeling reaches a steady state within seconds and stays at constant level over 30 minutes. Significant increases above this initial level are measured over periods of 2 hours. In our experimental conditions these increases can be considered due to albumin uptake. This uptake rises linearly with the albumin concentration between 0.5 and 50.0 mg/ml, and reaches 0.2 mg/gm cell protein or 4 x 105 molecules per cell. Compared to the incorporation of free amino acids in similar conditions, this value does not appear to contribute significantly to the N-metabolism of the tumor cells. Adsorption was generally greater than uptake. Both processes are linear functions of the same variable over the whole range of concentration tested. It is suggested that albumin is taken up by pinocytosis.
THE EXTRACELLULAR SPACE IN THE TOAD RETINA AS DEFINED BY THE DISTRIBUTION OF FERROCYANIDE
Authors: Lasansky Arnaldo , Wald Flora
Published: May 2004

Measurements of the uptake of compounds that ordinarily do not penetrate into cells have been a source of data on the size of the extracellular space in nervous tissue. The distribution of one such compound, ferrocyanide, has been studied in the toad retina by means of the light and electron microscopes. At the level of the light microscope, ferrocyanide, detected as Prussian blue, appears to penetrate predominantly within the inner processes of Müller cells. A diffuse background staining by Prussian blue can be noticed also at the inner retinal layers. At the level of the electron microscope, Müller cells exhibit an extensively developed system of channels which are formed by infoldings of the plasma membrane. Ferrocyanide, detected as copper ferrocyanide deposits, is found occupying the lumina of these channels and in the narrow intercellular gaps of the retina. These observations indicate that in the toad retina the extracellular medium includes the intercellular spaces plus a glial compartment formed by the infoldings of the plasma membrane of the Müller cells.
THE ISOLATION OF NUCLEI FROM EGGS AND EMBRYOS OF THE SEA URCHIN
Authors: Hinegardner Ralph T.
Published: May 2004

Nuclei can be isolated from the eggs and embryos of the sea urchin by a four step method: (1) washing with dextrose solution until the cells become weak, (2) cytolysis in 0.002 M Mg++ solution, (3) homogenization of the cytolyzed cells by agitation, and (4) separation of the nuclei from the rest of the homogenate by centrifugation on a layered sucrose gradient. Contamination of the isolated nuclei is less than 1 per cent. The yield varies between 20 per cent and 80 per cent depending on the developmental stage used.
CYTOPLASMIC DNA SYNTHESIS IN AMOEBA PROTEUS
Authors: Rabinovitch M. , Plaut W.
Published: May 2004

The incorporation of tritiated thymidine in Amoeba proteus was reinvestigated in order to see if it could be associated with microscopically detectable structures. Staining experiments with basic dyes, including the fluorochrome acridine orange, revealed the presence of large numbers of 0.3 to 0.5 µ particles in the cytoplasm of all cells studied. The effect of nuclease digestion on the dye affinity of the particles suggests that they contain DNA as well as RNA. Centrifugation of living cells at 10,000 g leads to the sedimentation of the particles in the centrifugal third of the ameba near the nucleus. Analysis of centrifuged cells which had been incubated with H3-thymidine showed a very high degree of correlation between the location of the nucleic acid-containing granules and that of acid-insoluble, deoxyribonuclease-sensitive labeled molecules and leads to the conclusion that cytoplasmic DNA synthesis in Amoeba proteus occurs in association with these particles.
CYTOPLASMIC DNA SYNTHESIS IN AMOEBA PROTEUS
Authors: Rabinovitch M. , Plaut W.
Published: May 2004

Nucleic acid-containing particles in the cytoplasm of Amoeba proteus (cf. reference 1) were counted after acridine orange staining. The number of particles per ameba was found to be correlated with cell age and size. Fresh daughters had a mean particle number of 5400, whereas predivision amebae contained around 11,000 particles. Amebae from two other strains contained similar particles. The particles were found to be clustered in fasted cells and redispersed after feeding. A marked increase in the particle population was noted in anucleate fragments. These results, together with those previously presented, suggest that the particles multiply intracellularly. Their nature and their relationship to previous work on nucleic acid labeling in Amoeba are discussed.
A STUDY OF THE NUCLEOSIDE TRI- AND DIPHOSPHATE ACTIVITIES OF RAT LIVER MICROSOMES
Authors: Ernster Lars , Jones Lois C.
Published: May 2004

Rat liver microsomes catalyze the hydrolysis of the triphosphates of adenosine, guanosine, uridine, cytidine, and inosine into the corresponding diphosphates and inorganic orthophosphate. The activities are stimulated by Na2S2O4, and inhibited by atebrin, chlorpromazine, sodium azide, and deaminothyroxine. Sodium deoxycholate inhibits the ATPase activity in a progressive manner; the release of orthophosphate from GTP and UTP is stimulated by low, and inhibited by high, concentrations of deoxycholate, and that from CTP and ITP is unaffected by low, and inhibited by high, concentrations of deoxycholate. Subfractionation of microsomes with deoxycholate into ribosomal, membrane, and soluble fractions reveals a concentration of the triphosphatase activity in the membrane fraction. Rat liver microsomes also catalyze the hydrolysis of the diphosphates of the above nucleosides into the corresponding monophosphates and inorganic orthophosphate. Deoxycholate strongly enhances the GDPase, UDPase, and IDPase activities while causing no activation or even inhibition of the ADPase and CDPase activities. The diphosphatase is unaffected by Na2S2O4 and is inhibited by azide and deaminothyroxine but not by atebrin or chlorpromazine. Upon fractionation of the microsomes with deoxycholate, a large part of the GDPase, UDPase, and IDPase activities is recovered in the soluble fraction. Mechanical disruption of the microsomes with an Ultra Turrax Blender both activates and releases the GDPase, UDPase, and IDPase activities, and the former effect occurs more readily than the latter. The GDPase, UDPase, and IDPase activities of the rat liver cell reside almost exclusively in the microsomal fraction, as revealed by comparative assays of the mitochondrial, microsomal, and final supernatant fractions of the homogenate. The microsomes exhibit relatively low nucleoside monophosphatase and inorganic pyrophosphatase activities, and these are unaffected by deoxycholate or mechanical treatment. Different approaches toward the function of the liver microsomal nucleoside tri- and diphosphatases are reported, and the possible physiological role of the two enzymes is discussed.
SYNTHESIS AND MIGRATION OF PROTEINS IN THE CELLS OF THE EXOCRINE PANCREAS AS REVEALED BY SPECIFIC ACTIVITY DETERMINATION FROM RADIOAUTOGRAPHS
Authors: Warshawsky H. , Leblond C. P. , Droz B.
Published: May 2004

Radioautographs of pancreatic acinar cells were prepared in rats and mice sacrificed at various times after injection of leucine-, glycine-, or methionine-H3. Measurements of radioactivity concentration (number of silver grains per unit area) and relative protein concentration (by microspectrophotometry of Millon-treated sections) yielded the mean specific activity of proteins in various regions of the acinar cells. The 2 to 5 minute radioautographs as well as the specific activity time curves demonstrate protein synthesis in ergastoplasm. From there, most newly synthesized proteins migrate to and accumulate in the Golgi zone. Then they spread to the whole zymogen region and, finally, enter the excretory ducts. An attempt at estimating turnover times indicated that two classes of proteins are synthesized in the ergastoplasm: "sedentary" with a slow turnover (62.5 hours) and "exportable" with rapid turnover (4.7 minutes). It is estimated that the exportable proteins spend approximately 11.7 minutes in the Golgi zone where they are built up into zymogen granules, and thereafter 36.0 minutes as fully formed zymogen granules, before they are released outside the acinar cell as pancreatic secretion. The mean life span of a zymogen granule in the cell is estimated to be 47.7 minutes.
ELECTRON MICROSCOPIC AUTORADIOGRAPHY
Authors: Koehler J. K. , Mühlethaler K. , Freywyssling A.
Published: May 2004

An improved method has been developed for the preparation of autoradiographs for electron optical study. The refinement lies principally in the routine production of uniformly thin layers of photographic emulsion over the tracer-labeled cell sections. This is accomplished by means of a centrifugal spreading mechanism. Maize root tips grown in the presence of H3-thymidine were examined electron microscopically by this technique and were found to display nuclear labeling with impressive clarity. The new procedure utilized here yields objects in which the finest cell structures are easily resolvable without recourse to gelatin digestion techniques.
DEVELOPMENT OF FEATHER KERATIN DURING EMBRYOGENESIS OF THE CHICK
Authors: Bell Eugene , Thathachari Y. T.
Published: May 2004

The development of keratin in 9 to 17 day embryonic chick feathers has been studied by x-ray diffraction and cytochemical methods. The x-ray diffraction pattern given by the 9-day feathers contains none of the features seen in the adult pattern. In the 10 to 11 day patterns, besides two diffuse rings centered at 4.7 A and 10 A, two sharp, rather weak rings are seen at 35 A and 4.2 A with slight preferred orientations about the equator and the meridian, respectively. At 12 days, in addition to the foregoing, a sharp intense equatorial reflection at ∼56 A is observed. On treatment with lipid solvents, the 35 A ring is removed; prolonged extraction removes the 4.2 A ring, while blurring the 56 A reflection and enhancing the central low angle scatter. The 14-day pattern shows, besides all the features seen in the earlier patterns, a 23 A meridional reflection and other meridional and near meridional reflections. All the basic features of the adult pattern are seen at this stage and remain essentially intact on lipid extraction. Beyond 14 days, the pattern remains essentially the same, only improving in clarity and detail. The 4.2 A ring seen in the 10 to 15 day pattern is scarcely detectable in the 16-day pattern. Cytochemical evidence indicates that extensive —S—S bond formation occurs between the 13th and 14th days. It is suggested that lipids serve as a framework for the developing keratin structure which acquires permanent stability through hydrogen bonds and disulfide cross-links. The relation between keratin synthesis and tissue architecture as well as cytodifferentiation is discussed.
MITOCHONDRIAL CHANGES IN THE LIVER OF ESSENTIAL FATTY ACID-DEFICIENT MICE
Authors: Wilson J. Walter , Leduc Elizabeth H.
Published: May 2004

Livers of mice on diets deficient in essential fatty acids (EFA) have been studied by light and electron microscopy. The most conspicuous changes occur in the mitochondria. In light microscopy the mitochondria appear very much enlarged in the periportal region of the lobule. In electron micrographs they have additional cristae, sometimes very abundant. ranged in stacks in the central cavity. The matrix may be more electron-opaque than normal. This is in contrast with the enlarged mitochondria appearing under other experimental conditions, where the cristae are reduced in number and the matrix is less electron-opaque. It is known that there is an uncoupling of oxidative phosphorylation in EFA-deficient mitochondria. As a hypothesis it is proposed that the uncoupling may be due to a molecular defect caused by the absence of EFA in the structure that determines the spatial relationship between the electron transport chain and oxidative phosphorylation. It is further tentatively suggested that the changes in mitochondria may be attributed to lack of ATP. The possibility is discussed that the mitochondrial changes are ineffective attempts at compensation for this lack.
THE FINE STRUCTURE OF THE GASTRIC MUCOSA IN THE BAT
Authors: Ito Susumu , Winchester Robert J.
Published: May 2004

A description of the cytology of the gastric mucosa is presented based upon an electron microscopic investigation of the bat stomach. The fine structure of the various cell types in this species is fundamentally similar to that of the corresponding cell types of other mammals, but the relative cell numbers and distribution are somewhat different. (a). The surface mucous cells are identified by their superficial location and by the character of their dense secretory granules. (b). The mucous neck cells are distinguished by a characteristically different appearance and distribution of their mucous granules, and by their varied shape and their location between parietal cells. (c). The parietal cells are very large and have unusually prominent secretory canaliculi and an extraordinary number of large mitochondria. (d). The chief cells are found at the base of the gastric glands and are similar in their fine structure to other zymogenic cells. They contain many large zymogen granules and have an extensively developed granular endoplasmic reticulum. The latter is sometimes aggregated in unusual, hexagonally packed straight tubules, each with twelve longitudinal rows of ribosomes uniformly spaced around its circumference and with the rows of ribosomes in precise register with those of adjoining tubules. (e). Argentaffin cells lodged between other cell types vary sufficiently in the structure of their mitochondria and the character of their specific granules to suggest that they are of more than one kind. The majority are at the base of the epithelium but some extend to the lumen and bear microvilli on their free surface.
LOCATION AND COMPOSITION OF SPORE MUCOPEPTIDE IN BACILLUS SPECIES
Authors: Warth A. D. , Ohye D. F. , Murrell W. G.
Published: May 2004

Spore integuments of Bacillus coagulans were prepared containing nearly all the hexosamine and α, ϵ-diaminopimelic acid (DAP) present in intact spores. Subsequent autolytic action resulted in the destruction and removal of the residual cortical structure and "cortical membrane" leaving the appearance of the inner and outer spore coats unchanged in electron micrographs. Concurrently, all the hexosamine and DAP in the preparation was released mainly as non-diffusible mucopeptide containing alanine, glutamic acid, DAP, and all the glucosamine and muramic acid. Some diffusible peptides containing alanine, glutamic acid, and DAP were also present but there was little protein or carbohydrate. Lysozyme digestion of integument preparations from heated spores of Bacillus 636, B. subtilis, B. coagulans, and B. stearothermophilus specifically removed the residual cortex and cortical membrane with the release of the mucopeptide. In B. cereus T, only the residual cortex and part of the mucopeptide were solubilized by lysozyme. The effect of several reagents and enzymes upon the appearance and removal of hexosamine from B. coagul ans spore integuments is reported. The results show that spore mucopeptide is mainly located in the residual cortex and cortical membrane and suggest that these structures consist essentially of mucopeptide. The implications of these results in relation to the "contractile cortex" theory of heat resistance in spores are discussed.
THYMIDINE DEGRADATION PRODUCTS IN PLANT TISSUES LABELED WITH TRITIATED THYMIDINE
Authors: Takats S. T. , Smellie R. M. S.
Published: May 2004

A study of the metabolic pathways of H3-thymidine utilization in buds of Lilium longiflorum and root tips of Vicia faba was undertaken in order to obtain information that might explain the binding of H3 from H3-thymidine in the cytoplasm of these plants. H3-thymidine was administered for various periods of time, the tissues were fixed and processed in the manner routinely used in preparation for sectioning and autoradiography, and the radioactivity removed in this way from the tissues was determined. It was found that the ethanol/acetic acid fixative contained the major portion of the radioactivity. Analysis of this extract by paper chromatography showed that the radioactivity was distributed among various degradation products of thymidine, principally ß-ureidoisobutyric acid and ß-aminoisobutyric acid. Time course experiments with Vicia showed that these degradation products rapidly appeared in the tissue during incubation with H3-thymidine, while H3-thymine appeared in the incubation medium. Preliminary studies indicated that Vicia root tips incubated with H3-dihydrothymine for 24 hours would bind a small amount of H3 non-specifically in the cells. It seems unlikely that utilization of degradation products of H3-thymidine is sufficient to explain labeling which is concentrated in the cytoplasm.
CYTOCHEMICAL STUDIES OF THE NUCLEOPROTEINS OF HELA CELLS INFECTED WITH HERPES VIRUS
Authors: Love Robert , Wildy Peter
Published: May 2004

The morphological and cytochemical changes in HeLa cells infected with herpes virus have been studied at frequent intervals during infection and related to the growth of virus and the multiplicity of the virus inoculum. Infection with a high multiplicity inoculum produced enlargement and extrusion of small ribonucleoprotein (RNP) bodies in the nucleoli (nucleolini) to form RNP bodies in the nucleoplasm (B bodies) beginning ½ hour after infection. 3 hours after infection, RNP of the pars amorpha appeared to diffuse into the adjacent nucleoplasm, where, ½ hour later, the classical type A inclusion or A body first appeared. The A bodies displaced the B bodies and the nucleoli and eventually filled the nucleus. 6 hours after infection, minute granules containing RNA, DNA, and non-histone protein appeared inside the A bodies (A granules) and increased in number until the late stages of infection, when they disappeared. 18 hours after infection, at the time when the A bodies came to fill the nucleus completely, extrusion of RNP from the nucleus produced cytoplasmic masses which have been termed C bodies. B bodies were formed in the majority of cells before the maturation of infectious virus, but the number of B bodies could not be correlated with the amount of virus in the cell or with the multiplicity of the inoculum. It is suggested that the formation of B bodies may be the result of inhibition of the onset of mitotic division by a mechanism which does not inhibit the formation of RNA in the nucleolini. The nature of the A bodies, the A granules, and the C bodies is discussed and it is concluded that the A granules may represent aggregations of maturing virus in the nucleus. The progression of some C mitotic metaphases to the formation of post-C mitotic multinucleated giant cells is described. These are distinct from syncytia formed by cell fusion.
AN ELECTRON MICROSCOPE STUDY OF DENERVATION ATROPHY IN RED AND WHITE SKELETAL MUSCLE FIBERS
Authors: Pellegrino Claudio , Franzini Clara
Published: May 2004

A study, mainly by electron microscopy, has been made on two leg muscles of rat, in the course of atrophy experimentally induced by total denervation. As a preliminary the chief distinctive features of the soleus, chosen as a representative of pure red muscle, and of the gastrocnemius, representative of pure white muscle, are described. Two major phases of atrophy, somewhat overlapping in time, were observed. In the first, a degenerative autolytic process takes place in areas of the fiber, with loss of striation. It can be detected as early as the 7th day, but the maximum is observed at the 14th day, and accounts for a gross weight loss of 50 per cent. The first alteration appears in the Z lines; disorder in the disposition of filaments then follows. The process occurs very rapidly, leaving large areas in the cell in which one can detect only ground substance, glycogen, rare randomly disposed vesicular elements, and some mitochondria. Several lysosomes and masses of lipoproteins, which assume the configuration of concentric lamellae, show up in these fibers. Subsequently large parts of the waste sarcoplasm are discarded into the intercellular spaces. In the second major phase the so called "simple" atrophy takes place. The process starts early, but its effects are more detectable after 1 month. In this period, single myofibrils undergo different degrees of reduction in diameter, while the spatial disposition of primary and secondary filaments inside the fibrils remains normal. The appearance of the fibrils in longitudinal sections suggests that the process takes place by the detachment of filaments from the periphery of the fibrils and by their subsequent breakdown in the interfibrillary spaces. The sarcoplasmic reticulum is still well preserved, and relatively overdeveloped. Mitochondria disappear in parallel with the contractile material.
ELECTRON MICROSCOPIC STUDIES ON THE INDIRECT FLIGHT MUSCLES OFDROSOPHILAMELANOGASTER
Authors: Shafiq S. Ahmad
Published: May 2004

The differentiation of the indirect flight muscles was studied in the various pupal stages of Drosophila. Fibrillar material originates in the young basophilic myoblasts in the form of short myofilamants distributed irregularly near the cell membranes. The filaments later become grouped into bundles (fibrils). Certain "Z bodies" appear to be important during this process. The "Z bodies" may possibly be centriolar derivatives and are the precursors of the Z bands. The first formed fibrils (having about 30 thick myofilaments) are already divided into sarcomeres by Z bands. These sarcomeres, however, seem to be shorter than those of the adult fibrils.The H band differentiates in fibrils having about 40 thick myofilaments; the fibrils constrict in the middle of each sarcomere during this process. The individual myofibrils increase from about 0.3 µ to 1.5 µ in diameter during development, apparently by addition of new filaments on the periphery of the fibrils. The ribosomes seem to be the only cytoplasmic inclusions which are closely associated with these growing myofibrils. Disintegration of the plasma membranes limiting individual myoblasts was commonly seen during development of flight muscles, supporting the view that the multinuclear condition of the fibers of these muscles is due to fusion of myoblasts.
AN ELECTRON MICROSCOPE STUDY OF THE DEVELOPMENT OF SV40 VIRUS
Authors: Granboulan Nicole , Tournier P. , Wicker R. , Bernhard W.
Published: May 2004

Kidney cells, predominantly from Cercopithecus monkeys but also from baboons, were infected in vitro with the SV40 virus. The infectious cycle was studied with the electron microscope by means of thin sections of cells fixed from 3 hours up to 11 days after infection. The frequency of virus formation and various nuclear and cytoplasmic lesions in relation to the infection are described. The virus particles appear in the nucleus in close contact with the chromatin. In a small number of cells they have been observed as early as 10 to 12 hours after infection, but most often they appear 24 to 48 hours afterward. Their mean diameter is 33 mµ. They have no membrane and are frequently arranged as crystal-like structures. In addition to the appearance of virus, one observes various lesions in the nucleoplasm and particularly in the nucleolus, which shows an early hypertrophy and produces unusual, dense condensations in contact with the nucleolonema. The importance of these nucleolar lesions and the relationship between the SV40 virus and the polyoma, common wart, and Shope papilloma viruses are discussed.
A HISTOCHEMICAL STUDY OF PHAGOCYTIC AND ENZYMATIC FUNCTIONS OF RABBIT MONONUCLEAR AND POLYMORPHONUCLEAR EXUDATE CELLS AND ALVEOLAR MACROPHAGES
Authors: Dannenberg Arthur M. , Burstone Marvin S. , Walter Paul C. , Kinsley June W.
Published: May 2004

The cytochrome oxidase (CO), aminopeptidase (AMP), succinic dehydrogenase (SD), acid phosphatase, esterase, and alkaline phosphatase of rabbit mononuclear (MN) and polymorphonuclear (PMN) peritoneal exudate cells and pulmonary alveolar macrophages (AM) - air dried on Mylar strips - were characterized by histochemical techniques with respect to stability, activators, inhibitors, and pH optima. A granule count method was established for the quantitation of these enzymes. For the acid phosphatase of MN, in which the most precise results were obtained, time, pH, substrate, and inhibitor curves resembled those commonly obtained biochemically. Five of these enzymes were usually more active in AM than MN, whereas the sixth, alkaline phosphatase, was not present in either cell type. AM also tended to consume more oxygen than MN and to divide more frequently. Since the most active cells in the population would be first involved in the host's defense against microbial agents, a comparison was made of the 10 per cent of the AM and MN with the highest enzymatic activities. No differences were found in the granule counts that were not reflected by the means. However, within a given AM population, cells containing ingested dust particles seemed to have higher enzymatic activities than those without particles. MN had greater acid phosphatase and SD activities than PMN and consumed more oxygen, but the CO, AMP, and esterase activites of both types of cells were of similar magnitude. PMN showed high alkaline phosphatase activity; MN showed none. A survey of the histochemical literature indicates that a positive correlation between the enzymatic and phagocytic activities of both MN and PMN exists in vivo.
A HISTOCHEMICAL ENZYME KINETIC SYSTEM APPLIED TO THE TRYPSIN-LIKE AMIDASE AND ESTERASE ACTIVITY IN HUMAN MAST CELLS
Authors: Hopsu Väinö K. , Glenner George G.
Published: May 2004

A method for the determination of enzyme kinetic constants Vm, Km, and Ki in a histochemical system has been devised. As a substitute for the reciprocal of the reaction velocity, the times necessary to reach a fixed amount of end product (the initial visible color) in a tissue site at various substrate concentrations are plotted, according to the method of Lineweaver and Burk, against the reciprocal of the substrate concentrations. The technique as applied to trypsin-like esterase and amidase activities in human mast cells indicates that a single enzyme or closely related enzymes in this site are responsible for the hydrolysis of both the amide and ester substrates and that typical trypsin substrates act as competitive inhibitors of their hydrolysis. Parallel biochemical studies were performed to evaluate the effect of certain aspects of the experimental histochemical method on a purified homospecific enzyme. The relative kinetic constants derived by the histochemical method afford a further means of characterizing enzymic activity in a histochemical system.
FINE STRUCTURE OF THE CILIARY EPITHELIUM OF THE RABBIT, WITH PARTICULAR REFERENCE TO "INFOLDED MEMBRANES," "VESICLES," AND THE EFFECTS OF DIAMOX
Authors: Tormey John Mcd.
Published: May 2004

The structure of the ciliary epithelium of the adult albino rabbit has been studied by electron microscopy. Material was fixed in osmium tetroxide and embedded in epoxy resins. Two hitherto unappreciated features of the non-pigmented epithelial layer are described. First, the "infolded plasma membranes" described by previous workers are shown by serial sections to be projections or interdigitations from adjacent cells. Second, the "rows of vesicles" described by previous workers are shown by serial sections to be part of an unusual form of smooth-surfaced tubular endoplasmic reticulum. The tubules are highly convoluted and extensively interconnected. They are arranged in sheets, so that a cross-section through a sheet gives the appearance of a row of vesicles. The other structural features of the ciliary epithelium are also described. Previous workers have reported that Diamox, which inhibits the secretory activity of the epithelium, causes profound structural changes. An effort has been made to confirm these reports under carefully controlled experimental conditions. It was found that secretion could be inhibited by a maximally effective dose of Diamox without the occurrence of any detectable structural changes. The physiological significance of these findings is discussed.
THE FINE STRUCTURE OF THE PURKINJE CELL
Authors: Herndon Robert M.
Published: May 2004

This paper describes the fine structure of the Purkinje cell of the rat cerebellum after fixation by perfusion with 1 per cent buffered osmium tetroxide. Structures described include a large Golgi apparatus, abundant Nissl substance, mitochondria, multivesicular bodies, osmiophilic granules, axodendritic and axosomatic synapses, the nucleus, the nucleolus, and the nucleolar body. A new and possibly unique relationship between mitochondria and subsurface cisterns is described. Possible functional correlations are discussed.
TURNOVER OF THE ORGANIC MATRIX OF CARTILAGE AND BONE AS VISUALIZED BY AUTORADIOGRAPHY
Authors: Campo Robert D. , Dziewiatkowski Dominic D.
Published: May 2004

Tibiae and humeri were removed from suckling rats at intervals of time after intraperitoneal injection of C14-L-phenylalanine, C14-L-leucine, S35-sulfate, or Ca45 Cl2. Autoradiograms of sections of the bones were prepared. Ca45 was removed from sections treated with dilute acetic acid; neither the concentration of S35 nor that of C14 was thereby markedly decreased. The S35 was removed from the demineralized sections on incubation in a solution of testicular hyaluronidase; the C14 was not. These results are interpreted as indicating that most of the S35 was present in the bones as chondroitin sulfate and that most of the C14 in the bones was present as protein. In the epiphyses, the C14 was initially concentrated in the proliferaing and hypertrophic chondrocytes, as was the S35. Secretion of S35- and C14-labeled materials into the matrix followed. Thereafter, however, although the S35-labeled material (chondroitin sulfate) persisted in the matrix, albeit at a diminished concentration, and was incorporated into metaphyseal bone, the C14-labeled material (protein) was almost completely removed from the matrix. When rats were given repeated doses of 17-ß-estradiol benzoate so as to inhibit resorption of their metaphyses, repeated doses of S35-sulfate were discerned as strata of S35 in their metaphyses. This was not the case if the rats received repeated doses of C14-L-phenylalanine or C14-L-leucine. On the basis of the results in these experiments it is suggested that although a portion of the chondroitin sulfate produced by the chondrocytes of the epiphyseal plate is retained and becomes part of the cores of metaphyseal spicules of bone, the protein of the proteinpolysaccharide is somehow removed before calcification of the cartilage ensues.
HYPERTROPHY OF THE HUMAN HEART AT THE LEVEL OF FINE STRUCTURE
Authors: Richter G. W. , Kellner A.
Published: May 2004

Muscle cells in the left ventricular walls of four markedly hypertrophied human hearts (above 600 gm) were compared with muscle cells in four non-hypertrophied hearts (up to 310 gm). Blocks of tissue obtained postmortem within 6 hours were processed for light and electron microscopy under conditions suitable for good preservation of myofibrils. A lattice parameter, qh, was defined as the number of myosin filaments per square micron in either H zones or A bands. By the use of methods of electron microscopy, qh was determined for perpendicular cross-sections of A bands in a large number of well preserved myofibrils of muscle cells in both groups of hearts. Statistical evaluation of the distributions of values of qh revealed no significant difference between the two groups. Thus, the myofilament lattices in hypertrophied cells were geometrically within normal limits. Planimetric measurements of cross-sectional areas of muscle fibers were made, using photomicrographs obtained from one representative hypertrophied heart and from one control. The size-frequency distribution of the measurements showed a marked difference between the two hearts, and confirmed the presence of hypertrophy of muscle cells. Counts of the number of myofibrils per muscle cell were determined for samples from the same two hearts, evaluated statistically, and found to be significantly higher for the hypertrophied heart. It is proposed (a) that myofibrils in hypertrophied heart muscle cells have filament lattices with geometrical arrangement and macromolecular parameters that are the same as those found in myofibrils of normal heart muscle cells; and (b) that in hypertrophy the number of myofilaments increases through formation of new myofibrils, and possibly also by addition of filaments to preexisting myofibrils.
EVIDENCE FOR AN ESSENTIALLY CONSTANT DURATION OF DNA SYNTHESIS IN RENEWING EPITHELIA OF THE ADULT MOUSE
Authors: Cameron Ivan L. , Greulich Richard C.
Published: May 2004

Tritiated thymidine autoradiography has been applied to several renewing epithelial tissues of the adult mouse in order to determine (a) the average time required for DNA synthesis; and (b) the temporal relationship of the synthesis period to the progenitor cycles of these populations. The average duration of DNA synthesis has been computed from curves describing the rates of appearance and disappearance of labeled metaphase figures in epithelia of colon, ileum, duodenum, esophagus, and oral cavity, in both normal and colchicine-treated animals. In general, application of colchicine does not significantly influence the derived values for DNA synthesis duration. The DNA synthetic time is remarkably similar in the tissues examined, despite wide differences in the times required for completion of the progenitor cycle (and for tissue renewal). Synthesis of DNA in these epithelial cells of the mouse requires approximately 7 hours. Agreement between this value and those derived by other investigators for mammalian cells in vivo and in vitro indicates that DNA synthetic time may be a temporal constant, of considerable potential utility to studies of cell proliferation. The advantages and shortcomings of this experimental approach to problems of cell population kinetics in vivo are discussed.
PROTEIN SYNTHESIS BY ISOLATED PEA NUCLEOLI
Authors: Birnstiel Max L. , Hyde Beal B.
Published: May 2004

A new method is described for the preparation of active, nucleus-free nucleoli and chromatin in relatively high purity and in sufficient quantities to permit biochemical and electron microscopic investigation. This method consists of disintegrating previously isolated nuclei by grinding with glass beads in an isotonic medium thus liberating structurally intact nucleoli and chromatin threads. Nucleoli and chromatin are then purified by differential centrifugation in Ficoll solutions. A study of the chemical composition, submicroscopic structure, and biological activity of the nucleolar preparation has been made. An equivalent study of the chromatin material has also been carried out in order to assess the significance of chromosomal contamination in nucleolar protein synthesis. The isolated nucleoli rapidly incorporate leucine-C14 into acid and base stable compounds in vitro. Such incorporation lasts for 20 minutes at 37°C and is enhanced by the addition of an energy-regenerating system and a complete amino acid mixture. It is independent of the nuclear Ph 5 enzymes. The bulk of the incorporated label is recovered in the residual, ribosome-like nucleolar protein fraction and a small percentage is found in the acid-extractable basic proteins. The rate of protein synthesis by isolated nucleoli is more rapid than that occurring in the chromatin fraction. This is taken as an additional proof that the nucleolus is the principal site of protein synthesis in the interphase pea nucleus.
DEMONSTRATION OF ACID PHOSPHATASE-CONTAINING GRANULES AND CYTOPLASMIC BODIES IN THE EPITHELIUM OF FOETAL RAT DUODENUM DURING CERTAIN STAGES OF DIFFERENTIATION
Authors: Behnke O.
Published: May 2004

Dense cytoplasmic bodies surrounded by one or two unit membranes and containing mitochondria, vesicles, ribosomes, rough and smooth surfaced endoplasmic reticulum, and lamellated membranes (myelin figures) have been observed in the differentiating mucosa of the duodenum of rat foetuses by electron microscopy. Generally, the cytoplasmic components in the bodies seem to be in varying stages of disintegration. The bodies are found in greatest number on the 17th and 18th day of gestation, i.e. at the onset of differentiation. At this period of development the epithelium is stratified, and the villus formation is initiated by invagination of the epithelium by buds of mesenchyme followed by a splitting of the epithelium along the sides of the invaginations. When the villi have formed, the stratified epithelium has changed to the simple columnar type and the dense bodies have largely disappeared. Simultaneously, the lumen has widened considerably. In a parallel study with the light microscope, frozen sections incubated for the demonstration of acid phosphatase activity revealed the reaction product to be localized in bodies of the same size and distribution as the dense bodies found by electron microscopy. Hence, it seems that the bodies are altered and enlarged lysosomes (cytolysomes) active during the intensive differentiative events in the small intestine during the last part of intra-uterine life.
FINE STRUCTURAL CHANGES IN THE FLAGELLUM OF THE SPERMATID IN EXPERIMENTAL CRYPTORCHIDISM OF THE RAT
Authors: Nagano Toshio
Published: May 2004

Rat testes were confined to the abdominal cavity by operation. After 1 to 26 days they were excised, fixed with osmium tetroxide, sectioned, and examined with the electron microscope. Changes in the axial filament complex of the spermatid flagellum appeared 2 days after operation, and the arrangement of filaments in the middle- and main pieces of some spermatid tails was disordered as compared to the 9 + 2 filament arrangement in the tails of the control spermatids and in other flagella and cilia. In cross-sections, the filaments in the experimental material were nine or less in number, and each of them was single and dense. Occasionally some were double, and in those instances one filament was dense and the other was light and tubular. The central filaments were obscure. In longitudinal sections,the filaments were not parallel to the main axis of the flagella or to each other. It was assumed that the central filaments were more sensitive to the experimental conditions than the peripheral pairs of filaments. Furthermore, the light filaments of the peripheral pairs were more sensitive than the dense filaments. Besides the axial filament complex, the fibrous sheath which surrounds it in the main piece was also changed. The plasma membrane of the changed flagella disappeared or became fragmented.
DIFFERENTIATION OF THE CHLOROPLAST OF ANTHOCEROS
Authors: Wilsenach R.
Published: May 2004

It has been demonstrated that the following changes accompany differentiation in the plastid of the liverwort Anthoceros eckloni. The inner membrane of the plastid folds to give rise to small vesicles which grow and may fuse to form thylakoids, i.e. flat bags. The thylakoids may "pair" to produce the doublets (thick membranes) of the grana. The doublets may be produced also by the invagination of a thylakoid. In both cases, the doublets are produced only where outside-to-outside contact of thylakoid membranes occurs, which supports the thesis that the thylakoid membranes are polarized. The thylakoids also fold outwards, anastomose, and may fuse. This results in a complicated membrane system, for which an interpretation becomes very difficult. The starch is produced in the matrix, and the pyrenoid bodies are interpreted as specialized regions of the matrix. Younger plastids have grana, but the mature plastid has so many doublets that distinct grana cannot be recognized. This interpretation of the changes which occur during the differentiation of the plastid differs radically from those of Menke (1961) and Manton (1962) who studied this same genus, but is compatible with findings in algae and angiosperms.
STRATIFICATION AND SUBSEQUENT BEHAVIOR OF PLANT CELL ORGANELLES
Authors: Bouck G. Benjamin
Published: May 2004

Living excised roots of pea were centrifuged at 20,000 g for 24 hours, and the behavior of organelles was followed by electron microscopy at various intervals after centrifugation. With these forces, organelles are not perceptibly or irreversibly damaged, nor is the viability of the whole root destroyed. Organelles stratify generally in the order of lipid (centripetal pole), vacuoles, smooth endoplasmic reticulum and dictyosomes, proplastids (without starch), mitochondria, rough endoplasmic reticulum, proplastids with starch. The nucleus distends from the vacuolar region to the extreme centrifugal pole of the cell, while the chromatin and nucleolus seek the centrifugal pole of the nucleus. During the redistribution of organelles the rough endoplasmic reticulum is among the first to reorient, and possible explanations for this are discussed. Mitochondria can be stretched elastically many times their original length, but proplastids seem fairly rigid. Small vacuoles, forced together during centrifugation, apparently may fuse to form a large unit. Lipid droplets, on the other hand, tend to remain separate. Dictyosomes and smooth endoplasmic reticulum layer in the same region of the centrifuged cell, indicating a density similarity between these two organelles.