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D F PARSONS

Publications and source records attributed to D F PARSONS.

16 recordsLinked to original sources
PubMed1964

CYTOCHROME CONTENT OF MITOCHONDRIA STRIPPED OF INNER MEMBRANE STRUCTURE.

The cytochrome composition of mitochondrial fractions which have been stripped of inner membrane subunits by exposure to high-frequency sound have been examined by lowtemperature spectroscopy. The ratio of cytochrome c to cytochrome a is not changed by the treatment, but the concentration of cytochrome per milligram of protein is increased and the concentrations of cytochromes c(1) and b change slightly. These cytochromes (c(1) and b) may be at least partly located in the subunits of the inner membrane, but the idea that all the respiratory components are located in single subunits of the mitochondrial cristae may be considered to be disproved.

Cytochromes↗
PubMed1963

CYTOCHROME FUNCTION IN RELATION TO INNER MEMBRANE STRUCTURE OF MITOCHONDRIA.

Projecting subunits of an average diameter of 80 A are found on the cristae of mitochondria prepared from the muscle of Ascaris lumbricoides. A spectroscopic examination of the cytochrome content of these mitochondria shows no detectable cytochrome c(1), a, or a(3) and does reveal cytochromes of types c and b. Subunits in the same size range are found in cytochrome c deficient mitochondria of the emergent bee, while the frequency of their occurrence along the cristae is decreased relative to the adult bee. Apparently, the cytochrome content of the respiratory chain is not related to the size of the subunits, but may be related to the frequency of occurrence of the subunits.

Animals↗
PubMed1962

An electron microscope study of radiation damage in the mouse oocyte.

Cytological changes occurring in young oocytes of the mouse, following whole-body x-irradiation, have been examined by light and electron microscopy. Two minutes after a dose of 200 r, a drop occurs in the number of mitochondria per oocyte. The normal number of mitochondria is restored in the next few minutes. Five to 6 hours after a dose of 7 r, and 30 to 45 minutes following a dose of 200 r, all the oocytes are markedly contracted. In the next 2 hours (at a dose of 7 r), some cells shrink further and become pycnotic, while others expand and show signs of karyolysis. Of the expanded cells, some (about 50 per cent of total young oocytes) become morphologically normal. In both pycnotic and karyolytic nuclei, the nucleolus was contracted but without loss of its fibrillar structure. The contracted nucleolus appeared similar to those seen in some nearly mature normal oocytes (these oocytes have a high natural death rate). No other cell type in the ovary was affected by doses of x-rays up to 200 r. Observations on the nucleus of the normal oocyte are included. In the dictyate stage of meiotic prophase the chromosomes were dispersed into bundles of 100 A microfibrils. The main component of the nucleolus was found to be tightly coiled fibrils of 60 to 100 A, which appear to have a close relationship with the microfibrils of the chromosomes.

Animals↗
PubMed1961

Electron microscopy of plasma-cell tumors of the mouse. I. MPC-1 and X5563 tumors.

An electron microscope study was made of a series of transplanted MPC-1 plasma-cell tumors carried by BALB/c mice. Large numbers of particles similar in morphology to virus particles were present inside the endoplasmic reticulum of tumor plasma cells. Very few particles were seen outside the cells or in ultracentrifuged preparations of the plasma or ascites fluid. In very early tumors particles were occasionally seen free in the cytoplasm adjacent to finely granular material. In general, the distribution of these particles inside endoplasmic reticulum is similar in early and late tumors. A few transplanted X5563 tumors of C3H mice were also examined. Large numbers of particles were found in the region of the Golgi apparatus in late X5663 tumors. A newly described cytoplasmic structure of plasma cells, here called a "granular body," appears to be associated with the formation of the particles. Particles present in MPC-1 tumors are exclusively of a doughnut form, whereas some of those in the inclusions of the late X5563 tumors show a dense center. Normal plasma cells, produced by inoculation of a modified Freund adjuvant into BALB/c mice. have been compared morphologically with tumor plasma cells of both tumor lines.

Animals↗
PubMed1961

Electron microscopy of plasma-cell tumors of the mouse. II. Tissue cultures of the X5563 tumor.

The X5563 tumor has been grown in tissue culture. Cells similar to those of the original tumor migrated from the explant and attached to the glass walls of the culture vessels. Electron microscopy showed that large numbers of particles, similar in morphology to virus particles, were associated with these cells after 7 days of culture. The two principal types of particles found in the tumor in vivo appear to be present in vitro. Many more of these particles, however, were larger and showed a more complex structure. Whereas the particles were mainly localized inside endoplasmic reticulum or the Golgi zone in the tumors in vivo, in the tissue culture the majority of the particles were associated with the plasma membrane and were found outside of the cells. The relation of the particles to the granular body is discussed as well as a possible relation to the mammary tumor agent.

Animals↗