Carl F. T. Mattern

Ultrastructure of the taste bud of the human fungiform papilla

SummaryThe taste bud of the human fungiform papilla was examined by electron microscopy. Typical type I, type II, and type III cells were found along with contact sites with nerve endings. Vesicles in nerve fibers contacting type I and type II cells suggest that these cells may receive efferent impulses, whereas vesicles and granules in type III cells adjacent to (afferent) nerve fibers support the view that type III cells are sensory receptors. All of these features are virtually indistinguishable from those previously reported in fungiform taste buds of other mammals.

Isolation and Characterization of DNA from Kinetoplasts of Leishmania enriettii

The DNA of Leishmania enriettii can be separated by equilibrium sedimentation in cesium chloride into a major band of density 1.721 and a minor component of density 1.699. DNA from isolated kinetoplasts of this protozoan was identified as the less dense minor component.

Electron microscopic observations on multiple polyoma virus-related particles

Abstract Isopycnic banding of small-plaque polyoma virus in CsCl produced four bands at densities 1.28, 1.29, 1.33, and 1.34. Examination of these fractions in the electron microscope revealed the upper band to consist of 48 mμ shells incompletely filled with PTA. These were interpreted as being 48 mμ shells with an internal 38 mμ shell. The second band consisted of three sizes of separated, capsomered shells 48, 38, and 22 mμ in diameter which are believed to consist of 72, 32, and 12 “capsomeres”, respectively. The lower two bands were not morphologically different, consisting of complete virus particles. A 26 mμ shell of DNA was shown in complete particles by uranyl acetate staining, and a 38 mμ capsomere shell was demonstrated in situ between the 26 mμ DNA shell and a ring of residual stain between the 48 and 38 mμ shells. These observations suggest that the polyoma virus may be constructed (from interior to exterior) of a 22 mμ shell of capsomeres, a thin shell of DNA, a 38 mμ shell of capsomeres and a 48 mμ protein shell. A fifth layer of phospholipid covers some particles to a diameter of about 60 mμ A similar picture of three sizes of spherical particles was seen with SV40 virus. Filamentous, capsomered forms were found in large number only in KBr “cushion” fractions; apparently filaments were destroyed by CsCl. Filaments also occurred in three general sizes, 22, 38, and 48 mμ Possible roles of filamentous forms in virus replication are discussed.

Replication of polyoma virus in mouse embryo cells: Electron microscopic observations

Abstract Single step replication of polyoma virus in mouse embryo (ME) cells has been examined by electron microscopy. Cells phagocytose individual virus particles or membrane bound aggregates into the cytoplasm. Individual particles appear in the cytoplasm as 50–60 mμ membrane-bounded viruses. Either 38 mμ or 50–60 mμ particles may be found in the larger phagocytic inclusions. As early as the eighth hour of infection, virus particles have been occasionally observed between the two nuclear membranes; however, at later periods they are frequently observed in this location. By the twentieth hour of infection, small, densely staining, bundles of filaments are observed in multiple loci in nuclei. These bundles increase in number with time and are often surrounded by typical 38 mμ “nuclear” virus particles which may form intranuclear crystals as early as 24 hours after infection. Virus in cells whose nuclei are degenerating exhibit a remarkable affinity for nuclear, cytoplasmic and cell surface membranes. These observations support the suggestion of Bernard et al. (1959) that the nuclear filament is a precursor of polyoma virus.

Replication of poliovirus in HeLa cells: Electron microscopic observations

Abstract Poliovirus-infected HeLa cells were examined by electron microscopy. Both nuclear and cytoplasmic changes were observed during the first 4 hours of infection. Nuclei of cells infected from 2 to 6 hours developed progressively more numerous extrusions which contained ribosome-like particles. These extrusions appeared to eventually become cytoplasmic inclusions. Changes in the cytoplasm were observed at about the fourth hour of infection, at which time clusters of small cytoplasmic vesicles appeared; occasionally they contained viruslike particles. By the sixth hour arrays of virus particles were found within cytoplasmic vesicles. From the sixth to the eighth hour these vesicles appeared to coalesce into large crystalline aggregates of virus. Eventually the large crystals of virus appeared to “melt.” The possible significance of these observations is discussed in relation to numerous other approaches to understanding the nature of replication of small RNA virus.

Revertants of mouse cells transformed by murine sarcoma virus: I. Characterization of flat and transformed sublines without a rescuable murine sarcoma virus

Abstract Murine sarcoma virus (MSV)-transformed mouse clonal cell lines produced variants with some properties of nontransformed cells. Such variant cells were epithelioid, contact inhibited, and grew to low density, and their low cloning efficiency in soft agar was similar to that of normal parental 3T3 cells. However, they contained murine leukemia (MuLV) group-specific antigen(s) without demonstrable virus production and reverse transcriptase activity. MSV could no longer be rescued from these flat variant cells by superinfection with MuLV, by cocultivation with normal 3T3 cells or by transspecies rescue into cat cells. An enhancement of sensitivity to MSV and MuLV infection was observed in all flat variant cultures. Flat variant clones spontaneously gave rise to retransformed cells during extended cultivation. Morphology, saturation density, and cloning efficiency in soft agar of cloned spontaneous retransformed cell lines were similar to the original MSV-transformed cells. However, they failed to demonstrate MuLV gs antigen(s), virus production, reverse transcriptase activity and a rescuable MSV genome. The spontaneously retransformed cells were susceptible to MSV and MuLV infection. After treatment with 5-iododeoxyuridine (IUrd), reverse transcriptase activity and virus particles were only rarely induced in flat variant or spontaneously retransformed clones. These particles were not infectious for the original host cells and were not induced in normal 3T3 cells or a majority of the variant clones. Chromosome studies of these variants suggested that the partial or complete loss of expression of transformation in variants might have been associated with an imbalance in the number of chromosomes mediating expression or suppression in these cells.

Isolation of a continuous epithelioid cell line, HBT-3, from a human breast carcinoma.

Summary A continuous line of human breast carcinoma cells, HBT-3, was established in culture following collagenase treatment of a mucus producing adenocarcinoma. The cells are epithelioid in appearance, multiply rapidly, have a cloning efficiency of approximately 70%, and exhibit an abnormal karyotype with a mode of 66-69 chromosomes/cell and 3 markers. Tumor material and pathological diagnosis were provided through the courtesy of Dr. J. D. Mashburn, Director of Laboratories, Washington Sanitarium and Hospital, Takoma Park, MD. Dr. C. S. Stulberg, Senior Research Associate, The Child Research Center of Michigan, Detroit, kindly performed the immunofluorescence cell typing tests. A portion of these studies was carried out at Bionetics Research Laboratories, Inc., Bethesda, MD, under contract 69-2160 from the Special Virus Cancer Program of the National Cancer Institute. Technical assistance of Cathy K. Smith, Nancy Tuttle Fuller, and Diane Robertson is gratefully acknowledged. The authors thank Drs. Peter J. Fischinger and Tadao Aoki of the National Cancer Institute for their advice and many helpful discussions.

Comparison of the DNA's obtained from brain nuclei and mitochondria of mice and from the nuclei and kinetoplasts of Leishmania enriettii

Abstract DNA has been isolated from mouse-brain-mitochondrial preparations, free of nuclear contamination. After purification, the buoyant density and thermal denaturation profiles of this DNA have been compared with those of mouse nuclear DNA, and with the nuclear and kinetoplast DNA of Leishmania enriettii . The buoyant density of mouse mitochondrial DNA was 1.701 and its T m 82.8°. The C-G content was 42 %, calculated from the density, and 33 %, calculated from its T m . The buoyant density of mouse nuclear DNA was 1.702, and its T m 86.2°, corresponding to a C-G content of 43 % and 41 %, respectively. The buoyant density of the Leishmania kinetoplast DNA was 1.702, and its T m 83.0°, corresponding to a G-C content of 43 % and 33 %, respectively. The buoyant density of the Leishmania nuclear DNA was 1.721 and its T m 92.8°, corresponding to a C-G content of 62 % and 57 %, respectively. On thermal denaturation, the initial hyperchromicity of the two nuclear DNAs was approx. 25 %, that of mitochondrial DNA about 29 %, and that of kinetoplast DNA about 8 %. The degree of renaturation of mitochondrial DNA was 21.5 %, that of kinetoplast DNA 78.6 %. Mouse-nuclear DNA renatured 10.3 %, but Leishmania nuclear DNA 36.4 %. From these and other data it was concluded that the DNA from the protozoal kinetoplast was more homogeneous than protozoal nuclear DNA. Both protozoal DNAs appeared more homogeneous than mouse-mitochondrial DNA, whereas mouse nuclear DNA was the most heterogeneous. The data are consistent with the theory regarding the existence of mitochondrial inheritance.

Some Physical and Chemical Properties of Coxsackie Viruses A9 and A10.

Abstract Procedures are described for the purification of Coxsackie virus A9, poliovirus MEF, and poliovirus Mahoney grown in monkey kidney cells and for Coxsackie viruses A10 and A14 grown in suckling mice. A number of physical properties of Coxsackie viruses were compared with those previously reported for polioviruses. The two viruses appear quite similar in size, density, RNA content, number of physical particles per infectious unit, and certain surface properties as manifested by their ready adsorption onto glass surfaces. Coxsackie and polioviruses differ significantly in their crystal lattice structure, nucleic acid base ratios, and ease of extraction of their nucleic acid with phenol.

Evidence of a contractile mechanism in the taste bud of the mouse fungiform papilla.

Abstract The taste pores of anesthetized mice were directly observed by means of an epimicroscope. After exposure to HCl vapor, the taste bud responded by extruding fluid from the pore. Within a few seconds the fluid receded leaving a ring of material. By electron microscopy the pore was seen to be filled with vesicles, presumably in a fluid matrix. A possible contractile mechanism is hypothesized; it consists of a long wavy bundle of tonofilaments whose extension and retraction could account for these observations.