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1.
The influence of fruit ingestion by the bat, Sturnira lilium, on germination of the seeds of the tree Solanum riparium was studied in a secondary rain forest in northwestern Argentina. Bat frequencies in disturbed areas were analyzed by mist net captures. Germination rates were determined for seeds collected from trees and bat feces. S. lilium was the most abundant fruit bat in the study area. Fruit digestion and the passage of seeds through the intestine did not significantly affect germination in S. riparium. In this case the fruit bats, therefore, probably provide only seed dispersal. 相似文献
2.
Vernon Shattuck Frank R. Katterman 《Biochemical and biophysical research communications》1982,109(3):1017-1025
When cotyledonary tissue of cotton are treated with the mutagen ethyl methanesulfonate and then germinated, an enhanced, unscheduled DNA synthesis response is observed, along with a concomitant increase in the thymidine triphosphate precursor pool size. The implications of these results are discussed in this paper. 相似文献
3.
G J Moore 《International journal of peptide and protein research》1985,26(5):469-481
The possible existence of intramolecular interactions involving the tyrosine and histidine residues in angiotensin II has been investigated by measuring the reactivities of the functional groups in the molecule. Angiotensin II catalyzed the hydrolysis of p-nitrophenylacetate in the pH range 6.6-8.2 at higher rates than were consistent with the reactivities of the free constituent functional groups, and had 2-4% of the activity of chymotrypsin between pH 6.6 and 7.5. Treatment of angiotensin II with acetic anhydride demonstrated that the tyrosine hydroxyl and the imidazole side-chain in angiotensin II acetylated and deacetylated at markedly higher rates than for the free amino acids, indicating increased nucleophilicities and the presence of intrinsic deacetylation mechanisms for these residues in angiotensin II. These findings are consistent with the presence of tyrosine hydroxyl-histidine-carboxylate charge relay system in ANG II in aqueous environments, and suggest that ANG II may act at membrane receptors by a mechanism which is analogous to that operating in serine proteases. 相似文献
4.
Frank J. Turano Kenneth Glade Wilson 《In vitro cellular & developmental biology. Plant》1985,21(3):135-139
Summary The feasibility of using plant cell culture to measure toxicity was determined by investigating the toxicological effects
of three chemical compounds, allyl alcohol, propargylglycine, and cadmium chloride, on cell cultures ofCatharanthus roseus G. Don (Madagascar periwinkle). Suspension cultures ofC. roseus were maintained in modified B5 medium and transferred every 5 d. Five-day-old cell cultures were exposed to various concentrations
(10,3,1,0.3,0.1,0.03,0.01,0.003,0.001,0.0003,0.0001, 0.00003, and 0.0 mM) of the toxicants in both acute and chronic toxicity tests.
In the acute test, cells were exposed to the toxicant for 24 h, washed three times with sterile medium, and plated in petri
plates with an equal volume of 1.4% agar medium. Cells in the chronic test were plated with an equal volume of 1.4% agar medium
containing various concentrations of the toxicant. Cells were incubated 28 d at 30°C in the dark. The colonies were counted
and the results plotted as percent survival versus toxicant concentration. The results indicate, at the concentrations tested,
thatC. roseus assay may be feasible in that it fulfills the criteria for a practical assay (e.g., rapid, simple, quantifiable, and reproducible).
This work was submitted to the faculty of Miami University in partial fulfillment of the requirements for the degree of Master
of Environmental Science, Institute of Environmental Sciences. 相似文献
5.
6.
Mignon Moore 《Ethnic and racial studies》2013,36(6):988-1005
William Julius Wilson’s model of adult joblessness, community disorganization and their effects on youth problem behaviour de-emphasizes the range in children’s outcomes across socially disorganized communities, and says little about the factors that influence this variation. It also does not address the processes by which family structure and relationships affect the well-being of African-American and poor youth. My work is part of a larger research agenda that has begun to address these issues by focusing on the differential rates of sexual activity among youth living in disadvantaged environments, and developing models to explain this variation. This work suggests that units of socially cohesive, stable adults exist among the social networks of successful children and families in poor neighbourhoods. It also points to the existence and functioning of alternative two-parent family structures and offers hypotheses for how family environment interacts with neighbourhood context to influence youth behaviour. 相似文献
7.
Sylvester J. T.; Harabin A. L.; Peake M. D.; Frank R. S. 《Journal of applied physiology》1980,49(5):820-825
8.
1,3-Propanediol (PAD) was fed to rats for 15 weeks, and its effects on hepatic and testicular DNA were studied. The control rats were fed a casein-based diet that contained 10% tocopherol-stripped corn oil with 30 IU of d,l-α-tocopherol acetate/kg; the experimental rats were fed the same diet with 500 ppm of PAD. Homogenates prepared from the livers of each group of rats converted 1,3-propanediol to malondialdehyde (MDA) with equal efficacy, but homogenates of testes did not catalyze this conversion. After 10–15 weeks of feeding the diets, the hepatic DNA of the rats fed PAD had less template activity, more bound tryptophan and more DNA-protein and interstrand DNA cross-links than that of the control rats. As measured by template activity and bound tryptophan, testicular DNA of the experimental rats was not different from that of the control rats; however, there was slightly more cross-linking in the testicular DNA of experimental rats than in that of control rats. Testes of the experimental rats contained more lipid-soluble fluorophores than did those of the control rats. The results are consistent with the conclusion that PAD was converted to MDA in vivo and that MDA is the reactive species that caused the observed biological damage. 相似文献
9.
10.
S M Goyal S A Schaub F M Wellings D Berman J S Glass C J Hurst D A Brashear C A Sorber B E Moore G Bitton 《Applied and environmental microbiology》1984,48(3):531-538
To select a tentative standard method for detection of viruses in sludge the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group initiated round robin comparative testing of two procedures that, after initial screening of several methodologies, were found to meet the basic criteria considered essential by the task group. Eight task group member laboratories agreed to perform round robin testing of the two candidate methods, namely, The Environmental Protection Agency or low pH-AlCl3 method and the Glass or sonication-extraction method. Five different types of sludge were tested. For each particular type of sludge, a single laboratory was designated to collect the sludge in a single sampling, make samples, and ship it to the participating laboratories. In most cases, participating laboratories completed all the tests within 48 h of sample arrival. To establish the reproducibility of the methods, each laboratory tested each sludge sample in triplicate for the two candidate virus methods. Each processed sludge sample was quantitatively assayed for viruses by the procedures of each individual round robin laboratory. To attain a more uniform standard of comparison, a sample of each processed sample from all laboratories was reassayed with one cell line and passage number by a single laboratory (Environmental Protection Agency Environmental Monitoring and Support Laboratory, Cincinnati, Ohio). When the data were statistically analyzed, the Environmental Protection Agency method was found to yield slightly higher virus recoveries for all sludge types, except the dewatered sludge. The precisions of both methods were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献