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At least 37 records · Page 2Linked to original sources
PubMed1979

Studies of X-ray-induced chromosome aberrations in cells of the black-tailed wallaby. I. Non-random exchange in peripheral blood cells irradiated in Go.

The distribution of exchanges between individual chromosome arms in mitotic peripheral blood cells following X-irradiation in Go has been measured. It was found that, although all arms exchanged with each other, there were small but significant departures from the frequencies expected on the basis of random breakage and exchange. It is suggested that non-randomness may reflect the non-uniform state of condensation of chromatin in Go lymphocytes.

Animals↗
PubMed1977

Oxygen affinity and 2,3-diphosphoglycerate in blood of Australian marsupials of differing body size.

Oxygen carriage and 2,3-diphosphoglycerate (2,3-DPG) levels have been measured in the blood of seven species of Australian marsupials ranging in size from 35 to 0.03 kg. They were Red and Grey Kangaroos, Wallaroo, Tammar Wallaby, Brush-tailed possum, Potoroo, and Brown Marsupial Mouse. Oxygen affinity decreased with decrease in adult body size, standard P50 (at 36 C) varying from 24.6 torr in the largest (Red Kangaroo) to 41.9 torr in the smallest (Brown Marsupial Mouse). The relationship between P50 and body size is similar to the relationship which has been described previously for eutherian mammals. The Bohr factor (--deltalog P50/deltapH) and value for Hill n were generally in the range found for other land-dwelling mammals. All species had 2,3-DPG in their erythrocytes acting as a regulator of oxygen affinity. The polymorphism at position beta 2 in hemoglobin of the Grey Kangaroo was shown to affect the respiratory properties of the molecule. When beta 2 = histidine, which has a positively charged side chain, erythrocyte 2,3-DPG was higher, and P50 was higher, than when beta 2 = glutamine which has a neutral side chain.

Animals↗
PubMed1978

The scaling of maximal oxygen consumption and pulmonary dimensions in small mammals.

This report has reexamined the relationship between standard and maximal rates of oxygen consumption (VO2std and VO2max) and pulmonary surface area in mammals whose weights extend over the lower half of the total log weight range in mammals. For combined groups of wild and laboratory animals with body weights of 2--3700 g, the following equations pertain: VO2std (ml . min-1) = 0.0602 . W0.727; VO2std, or the factorial aerobic scope, is nearly constant over this weight range at approximately 6.6 (range 5.8--7.1). In view of this finding, earlier studies relating SA or pulmonary diffusion capacity to VO2std are still appropriate models for pulmonary constraints on metabolic rate. The data summarized here suggest that, at least for wild species of mammals, pulmonary diffusion capacity may limit VO2max.

Animals↗
PubMed1979

Multiple sites for the initiation of microtubule assembly in mammalian cells.

The pattern of microtubule regrowth in mammalian fibroblast and epithelial cells has been examined by immunofluorescence of cytoskeletal preparations with antibody to tubulin. After reversal of treatment with colcemid, vinblastine or low temperature, microtubules appear to grow simultaneously from several distinct initiation sites located within 5 microns of the nucleus of mouse and human fibroblasts. Each site initiates the growth of 10-30 microtubules. More than 70% of the mouse fibroblasts have between 5 and 10 initiation sites with an average of 8. The human fibroblasts have an average of 5 sites per cell. The average number and numerical distribution of sites per fibroblast cell are not affected by time of exposure to colcemid or the concentration of colcemid applied to the cells. Multiple microtubule initiation sites are also observed during the process of microtubule depolymerization. In addition to growth from these complex initiation sites, microtubules appear to grow singly from the perinuclear region of human fibroblasts. The regrowth of individual microtubules from the perinuclear growth is especially prominent in epithelial cell lines from rat kangaroo and pig. These epithelial lines have only a single complex initiation site per cell. Two classes of complex initiation sites can be distinguished in microtubule regrowth experiments in human and mouse fibroblasts after exposure to griseofulvin. Microtubules first grow extensively from a single distinct site, which has approximately 20 microtubules growing from it and may be the centriole or centriolar pair. Subsequently, microtubules regrow from other perinuclear complex initiation sites. It thus appears that at least three distinct classes of initiation sites can be observed in mammalian cells: primary sites, which regrow microtubules first after griseofulvin treatment; secondary sites, which are distinct perinuclear sites and recover from griseofulvin treatment more slowly than the primary sites; and tertiary sites or sites of growth of single microtubules, also located near the cell nucleus.

Animals↗
PubMedDate not supplied

Genetic toxicology of lysergic acid diethylamide (LSD-25).

The acute and the chronic psychotomimetic potentials of the hallucinogen lysergic acid diethylamide (LSD-25) have been recognized for almost 40 years. That additional types of the biological effects should have come under scrutiny was directly attributable to widespread use and abuse of this drug on a world-wide basis. Although "genetic toxicology" encompasses a broad spectrum of disciplines, including many areas of highly specialized research, perhaps the most germane, and those on which this review has concentrated, are Clastogenicity, Mutagenicity, Teratogenicity and Oncogenicity. Based on our current understanding and interpretation of the available data, the genetic toxicology of LSD provides an excellent example of Newton's "third law of motion", e.g., to every force there is an equal and opposite reaction force. From the published material it is impossible to draw clear cut conclusions regarding any of the above "problem areas" in spite of the considerable scientific effort invested. Most of the in vitro studies performed on the clastogenicity of LSD indicate either suppression of mitosis or enhanced chromosome damage. However, extrapolation of such results to the in vivo situation is very difficult. With regard to in vivo human use of the drug, no concensus is attainable as to chromosome breakage and the inconsistencies within and between studies remain inexplicable. However, several of the "controlled" investigations assessing the in vivo effect of chemically pure LSD suggest a transient increase in lymphocyte chromosome breakage. On the other hand, the results of cytogenetic studies on experimental animals are contradictory. Although human studies are nonexistent, in those experimental organisms tested, using accepted techniques, LSD proved to be, at best, a weak mutagen, if mutagenic at all. Teratogenicity studies in animals are confusing due to the multitude of organisms and plethora of discriminant parameters studied. However, with regard to man there has been ample opportunity and one can conclude that LSD is not teratogenic. As to the drug's oncogenic potential, the 3 reported cases of leukemia in LSD users are most likely the result of coincidence.

Animals↗
PubMed1978

Reaction of tonofilament-like intermediate-sized filaments with antibodies raised against isolated defined polypeptides of bovine hoof prekeratin.

Total purified and reconstituted bovine hoof prekeratin, containing several polypeptides, as well as individual polypeptide size classes isolated therefrom were used as antigens in guinea pigs. The antibodies raised against these protein preparations were found to decorate the system of wavy arrays of tonofilament-like, intermediate-sized filaments present in various epithelial and epithelia-derived cells. Strong cross-reaction between different vertebrate species was noted, including amphibia. Positive results were obtained with original sera as well as with IgG fractions and antibodies made monospecific by chromatography on total bovine prekeratin covalently bound to Sepharose. Among the antisera raised against the different polypeptide size classes the most intense decoration of fibrillar arrays was obtained with antibodies against fraction 4 which contained polypeptides VI and VII.

Animals↗