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991.
Sex-related Resistance in Hamsters to Adenovirus-12 Oncogenesis II. Influence of Virus Dose 总被引:1,自引:0,他引:1
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A significantly higher proportion of female hamsters developed tumors than did males given the same dose of adenovirus-12 (Huie) at birth over a dose range from 10(5.0) to 10(7.0)tcd(50) for human embryonic kidney cells. The 50% tumor dose (td(50)) was calculated to be 10(5.90)tcd(50) for females and 10(6.27) for males. Tumor response patterns induced with approximate td(50) inocula, 10(6.0) for females and 10(6.3) for males, were quite similar. The greater susceptibility of females was not found to be characteristic of a single strain of hamsters; nor was it attributable to a single lot of virus, to a single type of human cell used to produce the virus, nor to the degree of purification of the virus inoculum. The inoculation route did not appear to be of importance. Inasmuch as the foregoing extrinsic factors were of little influence, it was concluded that the mechanism is host-mediated, presumably hormonally controlled. The possibility that female cells, independent of host control, are more susceptible to adenovirus-12 oncogenesis than male cells has not been explored. Tumor regression occurred in 20% of the 211 tumors in males and in 15% of the 355 tumors in females. Adenovirus-12 T-antibody was detected in all but six of 473 sera tested from tumor-bearing hamsters and in 50% of 94 sera tested from non-tumor-bearing animals given virus at birth. Antibodies in the latter group were detected almost exclusively by indirect immunofluorescence. This technique appears to be extremely sensitive for detection of low levels of adeno-12 T-antibodies. The implications of T-antibody in nontumor-bearing virus-injected hamsters are discussed. Sera from normal hamsters were free of T-antibody. 相似文献
992.
Histone differentiation and nuclear activity 总被引:4,自引:0,他引:4
Dr. David P. Bloch 《Chromosoma》1966,19(3):317-339
When fast green and eosin are used in combination to stain histones, nuclei display different affinities toward the dyes, some binding fast green exclusively, others binding eosin exclusively, and still others, both stains. In a given tissue, the frequencies of nuclei exhibiting the different colors remain fairly constant over a wide range of staining conditions. Nuclei of cells of the same type may stain differently, but when they are in the same stage of development or state of activity they tend to stain alike. Xenopus erythrocyte nuclei stain bright pink. Condensed mitotic and meiotic chromosomes stain purple. In the grasshopper spermatocyte, the main body of the interphase nucleus stains bright green, but the condensed chromosome stains purple. The mole crab sperm contains several distinct histone-like proteins, that differ in their amino acid compositions, within separate areas of the cell. In these sperms, the lysine-rich histones bind eosin, while the protamine-like protein and arginine-rich histone bind fast green. In general, the eosin and fast green bind preferentially to the lysine and arginine rich histones respectively, when the dyes are permitted to compete with one another. In several systems, including spermiogenesis and erythropoiesis, the aquisition of an eosinophilic component by the nuclei accompanies the slowing of RNA synthesis, and it is suggested that there may be a causal relationship between the two events, the eosinophilic histone effecting RNA synthesis within the nucleus as a whole. 相似文献
993.
Examination of living spermatid nuclei of Gryllus domesticus has revealed the presence of the same structures, the X chromosome, the round body and the axial core structures, which have been described from electron microscopic observations. The outer ribbons of the axial core structures and the round body are composed of 100 Å fibres indiscernible from and often continuous with the fibres composing the X chromosome. That the outer ribbons of the axial core structures and the round body are chromosomal is further substantiated by the results of cytochemical examinations of formaldehyde fixed material which show that the axial core structures and the round body contain RNA, DNA and basic protein. Neither acetic acid-ethanol nor cold ethanol fixation preserve the round body and the axial core structures suggesting that a protein may be responsible for maintenance of the central core structure. The central core structures are always found in close association with condensed chromatin in regions where the chromosome elements are about 1000 Å apart, suggesting that the relative state of condensation of the chromatin and the spacial relationship between condensed regions may be two of the chief factors concerned in central core formation. Maintainance of the condensed state of the chromatin, however, may in turn depend upon central core integrity.Herrn Prof. J. Seiler zu seinem 80. Geburtstag gewidmet. 相似文献
994.
David R. Weisbrot 《Genetics》1966,53(3):427-435
995.
Dieter Schäfer 《Cell and tissue research》1966,72(4):562-573
Zusammenfassung Durch eine kombinierte elektronenmikroskopisch-histochemische Methode nach Komnick wurden Natrium- und Chloridionen im proximalen Tubulusepithel der Rattenniere dargestellt. Während die als Natriumanimonat gefällten Natriumionen intrazellulär — d. h. intracytoplasmatisch, intramitochondrial, intranukleär — und extracellulär in den zwischenzelligen Faltenräumen vorkommen, beschränkt sich die Lokalisation der als AgCl gefällten Chloridionen weitgehend auf die Räume zwischen den einzelnen Tubulusepithelien.Die Möglichkeit einer passiven interzellulären Diffusion des Chloridions und eines aktiven transzellulären Transports des Natriumions wird diskutiert.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.
Auszugsweise vorgetragen auf dem 3. Symposium der Gesellschaft für Nephrologie, Berlin 1964. 相似文献
Summary Sodium and chloride ions are localized in the proximal tubule cells of the rat kidney by a combined electron-microscopic-histochemical method after Komnick. Sodium ions, precipitated as sodium-antimonate, are found in the cytoplasm, the mitochondrial matrix, and the nucleoplasm as well as extracellularly.Chloride ions, precipitated as AgCl, are mainly localized between adjacent tubule cells.The possibility of a passive intercellular diffusion of chloride ions and an active transcellular transport of sodium ions is discussed.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.
Auszugsweise vorgetragen auf dem 3. Symposium der Gesellschaft für Nephrologie, Berlin 1964. 相似文献
996.
Summary The distribution of five lysosomal enzymes (acid phosphatase, -glucosaminidase, -glucuronidase, sulphatase and E 600-resistant esterases) was studied in the pars distalis of the urodelian pituitary. Naphthol-AS-compounds coupled with hexazonium-pararosanilin yielded particularly good localization. The typical lysosomal picture and a basically similar distribution were obtained throughout. The reaction product was mainly found in the globules of the globular basophils (-cells) reported as gonatropin producing cells by several authors. Some speculations on the possible function of the high amount of the lysosomal enzymes in the globular basophils are made.Dedicated to Professor W. Bargmann on his 60th birthday.This work was partly supported by a grant from Deutscher Akademischer Austauschdienst, Bad Godesberg. 相似文献
997.
David B. Slautterback 《The Journal of cell biology》1965,24(1):1-22
The fine structure of mitochondria from the ventricular myocardium of canaries, sparrows, zebra finches, quail, and geese has been studied. The first three of these birds have very fast heart rates, the quail being intermediate, and the goose has a relatively slow rate. The canary heart has a unique form of mitochondrion containing large, parallel arrays of zigzag or angled cristae. Other cristae, continuous with the zigzag ones and also occupying large parts of the mitochondrial volume, are named retiform because of the hexagonal network which they form, sometimes in a single plane and sometimes three dimensional. These two types of cristae appear to be interconnectible. It is possible that there is a direct functional significance in these peculiar forms, but, in any case, the relative constancy of dimensions in these arrays is probably related to specific properties of the molecules of which the cristal membrane is composed. It is also demonstrated that this membrane is composed in part of approximately 30-A particles which are believed to be protein molecules. This unusual mitochondrial morphology is not seen either in the other fast bird hearts or in the slower ones, so that there is neither a simple correlation with heart rate nor probably with the separate parts of the cardiac cycle. Although none of the other four hearts shows more than an occasional angled crista, there does seem to be a rather gross correlation between heart rate and mitochondrial size and complexity of crista structure, but no correlation with presence or absence of zigzag forms. The cristae of quail heart mitochondria are disposed in unusually large close-packed whorls. 相似文献
998.
THE INFLUENCE OF PRECURSOR POOL SIZE ON MITOCHONDRIAL COMPOSITION IN NEUROSPORA CRASSA 总被引:18,自引:7,他引:11
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David J. L. Luck 《The Journal of cell biology》1965,24(3):445-460
The chemical composition of mitochondria obtained from exponentially growing Neurospora can be varied by addition of choline or amino acids to the culture medium. The variation affects the phospholipid to protein ratio, and the density of mitochondria as determined by isopycnic centrifugation in sucrose gradients. These variations have been observed in biochemical mutant strains as well as wild type cultures. In a choline-requiring strain, two levels of choline supplementation to the medium have been defined: a low choline concentration just adequate to support maximal logarithmic growth, and a high choline concentration which permits maximal incorporation of radioactive choline into cellular lipids. Mitochondria isolated from cultures growing at the low choline concentration have one-half the phospholipid to protein ratio of those from high choline cultures, and their density is significantly higher. Artificial mixtures of the two types of mitochondria can be resolved into two populations by isopycnic centrifugation. The concentration of cytochromes (measured by mitochondrial difference spectra) and of malate and succinate dehydrogenases (measured by enzyme activity) were the same in both types of mitochondria, on a protein basis. The results suggest that during growth of the mitochondrial mass, the incorporation of phospholipid and protein components can vary independently. Direct kinetic measurements did indeed show that choline, added to a culture growing at low choline concentration, was incorporated into mitochondrial lipids at a rate faster than the incorporation of protein. The mitochondrial phospholipid to protein ratio can also be influenced by the level of leucine supplementation to a leucine-requiring mutant, so that with leucine concentrations above those required for maximal exponential growth, mitochondria of increasing density and decreasing phospholipid to protein ratio are produced. Additions of choline or amino acids to the minimal medium of wild type cultures influence mitochondrial composition in a manner directly comparable to that observed in biochemical mutant strains. The results suggest that mitochondrial composition, in general, is determined by rates of incorporation of the two major components, phospholipid and protein; that these rates can vary independently in response to precursor concentration in the culture medium; and that they normally operate at a precursor (substrate) concentration below saturation level. 相似文献
999.
1000.
AN ORDERED FILAMENTOUS COMPONENT IN SCIARA (DIPTERA) SALIVARY GLAND CELL NUCLEI 总被引:1,自引:1,他引:0
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David M. Phillips 《The Journal of cell biology》1965,26(2):677-683