Feeding of the Bat,Sturnira lilium,on Fruits of Solanum riparium Influences Dispersal of this Pioneer Tree in Forests of Northwestern Argentina

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.     

Enhanced unscheduled DNA synthesis in the cotyledons of Gossypium,barbadense L. by ethyl methanesulfonate (EMS)

When cotyledonary tissue of $\text{G.}\text{,}\text{barbadense}$ 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.     

Evaluation of acute and chronic toxicity of selected compounds in higher plants using cell culture

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.     

Cross-linking of DNA in liver and testes of rats fed 1,3-propanediol

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.     

Influence of ionic strength and pH on the interaction between high-affinity heparin and antithrombin

Binding constants for the binding of high-affinity heparin to antithrombin at different ionic strengths were determined by fluorescence titrations and were also estimated from dissociation curves of the heparin-antithrombin complex. These curves were monitored by near-ultraviolet circular dichroism or fluorescence. The dependence of the binding constant on the activity of NaCl suggested that maximally 5–6 charged groups are directly involved in the interaction between the two macromolecules. Major pH-dependent changes of the interaction, as evident by changes of the spectroscopic properties of the complex between the molecules, were found to occur below pH 5.5 and above pH 8.5. The acid change, which was irreversible, was most likely caused by an irreversible conformational change of antithrombin. At alkaline pH, however, the gross conformation of antithrombin was stable up to pH 12, while the affinity of high-affinity heparin for antithrombin began to decrease markedly at pH 8.5. The dissociation curve, which was reversible, had a midpoint around pH 9.5. This is compatible with the loss of affinity being caused by either a local conformational change, by ionization of tyrosine or by titration of one or more amino groups.     

Pathogenicity for Chickens of a Paramyxovirus Type 1, Isolated from Racing Pigeons in Sweden

Strains of paramyxovirus type 1 (PMV-1) have been isolated from diseased racing pigeons in Sweden. One of these isolates was selected for studies of the pathogenicity and contagiousness in chickens. The same isolate was previously found to have a high intravenous pathogenicity index (IVPI) in 6 weeks old chickens. In three experiments it was found that the PMV-1 isolate was very pathogenic for 1 week old chickens but not pathogenic for 120 day old pullets inoculated intranasally and ocularly. Symptoms in the young chickens were similar to those seen in the neurotropic form of Newcastle disease. The mortality was high and the incubation period 5–11 days. The disease easily spread to young chickens kept in contact with diseased birds. The microscopic examination revealed an interstitial nonpurulent pneumonia and a nonpurulent encephalitis in the young chickens. In the pullets the only finding was a mild encephalitis. PMV-1 was recovered from all young chickens but not from the pullets. Both the chickens and the inoculated pullets developed antibodies to PMV-1.     

Rabbit small intestine does not contain an annexin II/caveolin 1 complex as a target for 2-azetidinone cholesterol absorption inhibitors

Intestinal cholesterol absorption is specifically inhibited by the 2-azetidinone cholesterol absorption inhibitor ezetimibe. Photoreactive ezetimibe analogues specifically label a 145-kDa protein in the brush border membrane of enterocytes from rabbit small intestine identified as aminopeptidase N (CD13). In zebrafish and mouse small intestinal cytosol, a heterocomplex of M_r 52 kDa between annexin II and caveolin 1 was suggested as a target of ezetimibe. In contrast, in the cytosol and brush border membrane vesicles (BBMV) from rabbit small intestine of control animals or rabbits treated with the nonabsorbable cholesterol absorption inhibitor AVE 5530, both annexin II and caveolin 1 were exclusively present as monomers without any heterocomplex formation. Upon immunoprecipitation with annexin II a 52-kDa band was observed after immunostaining with annexin II antibodies, whereas no staining of a 52-kDa band occurred with anti-caveolin 1 antibodies. Vice versa, a 52-kDa band obtained by immunoprecipitation with caveolin 1 antibodies did not stain with annexin II-antibodies. The intensity of the 52-kDa band was dependent on the amount of antibody and was also observed with anti-actin or anti-APN antibodies suggesting that the 52-kDa band is a biochemical artefact. After incubation of cytosol or BBMV with radioactively labelled ezetimibe analogues, no significant amounts of the ezetimibe analogues could be detected in the immunoprecipitate with caveolin-1 or annexin II antibodies. Photoaffinity labelling of rabbit small intestinal BBMV with ezetimibe analogues did not result in labelling of proteins being immunoreactive with annexin II, caveolin 1 or a 52-kDa heterocomplex. These findings indicate that the rabbit small intestine does not contain an annexin II/caveolin 1 heterocomplex as a target for ezetimibe.