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61.
Rats were injected subcutaneously for 147 consecutive days with large volumes of urine from control subjects and from patients with Huntington's chorea (HC) in an effort to test for presence of a possible neurotoxic substance in HC. No evidence of illness was observed in animals treated with HC urine, and their behavior did not differ from animals treated with control urine. After rats were sacrificed, striatum was examined for the biochemical and neuropathological changes seen in human striatum in HC. No deficiency of γ-aminobutyric acid content, nor reduction in activities of glutamic acid decarboxylase and choline acetyltransferase, was found in striatum of rats chronically treated with HC urine. Also, no significant differences were found between striatum of control and experimental rats by light or electron microscopy. These results neither support for exclude the possibility of a neurotoxic mechanism for the neuronal loss characteristic of HC. 相似文献
62.
The polysaccharide of P. hymantophora has been shown to be composed of (1→4)-linked galactopyranosyl, (1→3)-linked galactopyranosyl, (1→3)-linked galactopyranosyl 2- and 4-sulphate and 2,6-disulphate residues. The (1→3)- and (1→4)-linked units are present in approximately equal amounts. The polysaccharide of P. hieroglyphica has been shown to possess (1→4)-linked galactopyranosyl, (1→3)-linked galactopyranosyl, and (1→3)-linked galactopyranosyl 2- and 4-sulphate residues. The (1→3)- and (1→4)-linked units are present in a 4:1 ratio. Both polysaccharides contain small proportions of non-reducing xylosyl end-groups. 相似文献
63.
64.
Lois K. Miller Scott G. Franzblau Hugh W. Homan Leslie P. Kish 《Journal of invertebrate pathology》1980,36(2):159-165
A variant of the baculovirus, Autographa californica nuclear polyhedrosis virus, has been isolated in Idaho during an epizootic disease in a field population of A. californica. Genotypic characterization indicates that the virus is distinct from variants previously characterized. Analysis of five clones, derived by plaque purification in cell culture, indicates relative homogeneity of the original virus isolate. Further exploration of the factors involved in natural genetic variability of baculoviruses is appropriate. 相似文献
65.
Shirley A. Crawford 《Hydrobiologia》1979,62(1):17-31
Four aged Madison County, New York farm ponds were selected to see if various treatments could be used to restore the water quality. One pond was untreated and used as a control; another pond was partially drained and exposed to the drying and oxidizing effects of the air over the fall and winter; the other two ponds were drained and the accumulated sediment removed by bulldozing. In these latter two ponds, Chara vulgaris vegetation was inoculated following the restoration process. C. vulgaris growth rapidly became the dominant producer where this inoculation was accomplished in the fall of 1976, and it is expected that the other pond will also become a C. vulgaris pond in 1978 — after its oogonia have undergone the requisite winter dormancy period.Early C. vulgaris growth was found to be associated with clear water conditions and lessened phytoplankton growth; short, bushy, light-inhibited growth by the algae stabilized the bottom against wind-caused turbidity because of its rhizoidal growth within the substrate. Pioneer C. vulgaris growth was also found to be highly productive, significantly lowering the pond's CO2 readings.Investigators of aquatic systems are cautioned to be cognizant of the effect of epiphytic growth on successional events in such environments. Such epiphytes are surely important, if not prime, causes of the demise of various aquatic macrophytes.The partial draining and exposing of a pond over the fall and winter did not yield significantly improved water conditions. 相似文献
66.
Summary The swim bladder of the cyprinid Carassius auratus (goldfish) is a two-chambered organ connected to the esophagus by a pneumatic duct. The anterior chamber is lined by a single type of squamous epithelial cell. Two types of epithelial cells are present in the posterior chamber. Flattened cells with differences in the electron density of the cytoplasm line most of the chamber. Darker cells generally contain large amounts of glycogen. Cuboidal epithelial cells also occur in the posterior chamber. A glandular layer external to the muscularis in the posterior chamber is composed of large cells containing little glycogen, an extensive Golgi apparatus, and numerous mitochondria with single large granules. Capillaries and nerves are present in large numbers in this layer. Blood vessels form micro-retia mirabilia in the submuscular layer external to the glandular layer. Vessels are of two distinct types with wide lumina and flattened endothelium characterizing the venous vessels. Arterial vessels have smaller lumina, thick endothelial cells with prominent pinocytotic vesicles, and surrounding pericytes. Collagen is present in three forms in this swim bladder — large tactoids in the tunica externa of the anterior chamber, smaller tactoids in the lamina propria of the posterior chamber, and small fibrils in all other areas.Supported by a Young Investigator Pulmonary Research Grant # 1 R23 HL 19593-01 and by HL 23338-01 from the National Institutes of Health 相似文献
67.
Shirley H. Kovacs Paul F. Agris 《In vitro cellular & developmental biology. Plant》1979,15(5):329-341
Summary The melanoma of Sinclair swine exhibits several characteristics similar to human melanoma but demonstrates an unusually high
incidence of spontaneous regression. A total of 66 finite cell lines derived from 21 swine melanotic lesions, both cutaneous
and visceral, were studied in vitro over their life spans of up to 14 months. The growth characteristics of the cultures varied
with the age of the swine from which the tumors were obtained. Cell cultures of tumors obtained from swine aged less than
2 months grew steadily in culture with a population-doubling time of 120 to 180 hr until growth and division ceased after
a maximum of 25 to 35 population doublings (6 to 8 passages). Cell culture of tumors obtained from swine aged 3 months or
older showed a biphasic growth pattern with an early slow growth rate (population-doubling time 120 to 160 hr), which shifted
after 3 to 6 passages to a faster rate (80 to 110 hr population-doubling time) until termination of growth and division after
a maximum of 75 to 85 population doublings (18 to 20 passages). The cultures were morphologically heterogeneous including
cuboidal, spindle and dendritic cell types. Electron microscopy showed classic melanosomes only in the primary and passage
1 cultures although vesicular inclusions were numerous in later-passage cells. However, continued melanin synthesis was indicated
by the spectroscopic characteristics of material obtained from medium of passage 8 cultures and by DOPA staining of cultures
as advanced as passage 18.
This work was supported by a grant from the NIH, NCI (2 P01 CA 08023-11A1). 相似文献
68.
69.
Shirley E. Hawkins 《Journal of theoretical biology》1976,62(2):299-313
Progress on various aspects of nucleic acids and protein synthesis in amoebae has been reviewed. The RNA molecules involved in the character changes seen after micro-injection of non-homologous cytoplasmic fractions have been isolated after polyacrylamide gel electrophoresis, and their approximate molecular weights calculated. Injection of these RNA molecules was shown to alter the response of recipient cells to growth in streptomycin and neomycin.The relative molecular weights of cytoplasmic ribosomal RNAs have been estimated using both aqueous and formamide gel electrophoresis. Some attempts to characterize the nuclear RNAs seen on aqueous polyacrylamide gels, and to evaluate this data with that published by other workers have been made. Results from assays of DNA- and RNA-directed DNA polymerase activity are considered in relation to those from other eukaryotes.Problems arising after attempts to use rabbit globin messenger RNA to direct globin synthesis in amoebae, and the possibilities of using minature gel systems and small cell numbers to identify proteins and RNAs after various experimental treatments are discussed. 相似文献
70.