Differential uptake and metabolism of sitosterol and cholesterol by Achlya, Pythium, and Phytophthora species.

The relative ability of isolates of Achlya bisexualis and A. ambisexualis and isolates of Pythium and Phytophthora to take up and metabolize sitosterol and cholesterol was studied. Species of Pythium and Phytophthora took up cholesterol and sitosterol efficiently, whereas Achlya species took up booth sterols inefficiently. Species of Pythium and Phytophthora produced a polar metabolite and esters from sitosterol as they did from cholesterol. Achlya species did not produce the polar metabolite from either sterol. In these experiments Achlya species produced esters only from cholesterol; however, their failure to produce esters from sitosterol may have been due to the higher sitosterol than cholesterol concentration.     

In vitro organogenesis and plant regeneration from leaves of Solanum candidum Lindl,S. quitoense Lam. (naranjilla) and S. sessiliflorum Dunal

Adventitious shoots and roots were regenerated from leaf segments of 3 Solanum species: S. candidum Lindl., S. quitoense Lam. and S. sessiliflorum Dunal. Leaf explants differentiated shoots on modified MS medium supplemented with 23–163 M kinetin and 0–5.7 µM indoleacetic acid (IAA). Excised shoots were induced to form roots by transfer to media with benzyladenine (BA) and naphthaleneacetic acid (NAA) at 0.09 and 0.11 µM respectively for S. quitoense and 0.01 µM NAA for S. candidum and S. sessiliflorum. Adventitious roots were produced directly from leaf explants with 0–140 µM kinetin and 0–5.7 µM IAA in combination. Rooted plants were successfully established in the greenhouse.     

Inactivation of Giardia lamblia and Giardia canis cysts by combined and free chlorine

Free chlorine and a combined organic N-chloramine (3-chloro-4,4-dimethyl-2-oxazolidinone, compound 1) were compared for efficacy as disinfectants against an admixture of cysts of Giardia lamblia and Giardia canis in water solution under a variety of test conditions; variables were pH, temperature, and water quality. In general, compound 1 was found to reduce the giardial excystation in the solutions at lower concentration or shorter contact time at a given total chlorine concentration than did free chlorine.     

Consequences of a mixed reproductive system in the hog peanut,Amphicarpaea bracteata, (Fabaceae)

Summary The forest annual, Amphicarpaea bracteata L. can reproduce via aerial chasmogamous, aerial cleistogamous, and subterranean cleistogamous flowers. Both plant size and light intensity influenced the utilization of the three modes of reproduction. chasmogamous and aerial cleistogamous flower number and the ratio of chasmogamous flowers to the total number of aerial flowers increased with plant size. The latter demonstrated a shift to xenogamy and outbreeding in larger plants. Light intensity indirectly influenced reproductive modes through its infuence on plant size. Seed set by both types of aerial flowers was low and unrelated to plant size. Subterranean seed number and the total dry weight of subterranean seeds per plant increased with size. The subterranean seeds of Amphicarpaea bracteata are thirty-four times larger than the aerial seeds (fresh weight). Under field conditions, subterranean seeds had greater germination after one year than acrial seeds. The plants arising from subterranean seeds were significantly larger and more fecund than those from aerial seeds. Seeds produced by aerial cleistogamous, hand selfpollinated chasmogamous, and naturally pollinated chasmogamous flowers had equivalent germination rates and produced plants of equal size and fecundity. This suggests that the outbred progeny from chasmogamous flowers have no advantage over the inbred progeny from aerial cleistogamous flowers.     

Comparison of the roles of Ostracods and Cladocerans in regulating community structure and metabolism in freshwater microcosms

Laboratory microcosms were used to compare the effects of the littoral ostracod Cypridopsis vidua and the planktonic cladoceran Daphnia magna on community structure and metabolism. Filter-feeding by cladocerans, both in the presence and absence of ostracods, greatly reduced the abundance of planktonic algae when D. magna reached peak density around day 50; rotifers and euglenids were then limited to flocculent matter on the container bottom. Both net production and community respiration rates decreased as community composition changed. Microcosms containing ostracods as the only microcrustacean showed little reduction in total algal numbers but the otherwise dominant alga, Scenedesmus spp., was replaced by Ankistrodesmus spp. when peak ostracod density was reached around day 100. Rotifers were completely eliminated but euglenids were able to coexist with ostracods. Ostracods impacted community metabolism less than cladocerans, but depressed respiration slightly more than net production.     

Labeling of fructans in winter wheat stems

Fructans synthesized from newly formed assimilates accumulate in wheat stems as nonstructural carbohydrates. Experiments performed tested the hypothesis that the fructose moiety from translocated sucrose is used preferentially in biosynthesis of these fructans. Results indicated: (a) a large percentage of labeled sucrose was translocated and unloaded in an unaltered state; and (b) sucrose contributed its fructose moiety to fructan synthesis in stems.     

Diurnal fluctuations in cotton leaf carbon export, carbohydrate content, and sucrose synthesizing enzymes

In fully expanded leaves of greenhouse-grown cotton (Gossypium hirsutum L., cv Coker 100) plants, carbon export, starch accumulation rate, and carbon exchange rate exhibited different behavior during the light period. Starch accumulation rates were relatively constant during the light period, whereas carbon export rate was greater in the afternoon than in the morning even though the carbon exchange rate peaked about noon. Sucrose levels increased throughout the light period and dropped sharply with the onset of darkness; hexose levels were relatively constant except for a slight peak in the early morning. Sucrose synthase, usually thought to be a degradative enzyme, was found in unusually high activities in cotton leaf. Both sucrose synthase and sucrose phosphate synthetase activities were found to fluctuate diurnally in cotton leaves but with different rhythms. Diurnal fluctuations in the rate of sucrose export were generally aligned with sucrose phosphate synthase activity during the light period but not with sucrose synthase activity; neither enzyme activity correlated with carbon export during the dark. Cotton leaf sucrose phosphate synthase activity was sufficient to account for the observed carbon export rates; there is no need to invoke sucrose synthase as a synthetic enzyme in mature cotton leaves. During the dark a significant correlation was found between starch degradation rate and leaf carbon export. These results indicate that carbon partitioning in cotton leaf is somewhat independent of the carbon exchange rate and that leaf carbon export rate may be linked to sucrose formation and content during the light period and to starch breakdown in the dark.     

Lymphatic endothelial celline (CH3) from a recurrent retroperitoneal lymphangioma

Summary An endothelial cell line derived from a massive recurrent chyle-containing retroperitoneal lymphangioma was isolated in monolayer culture. Scanning and transmission electron microscopy and immunohistochemistry confirmed a close resemblance to blood vascular endothelium with typical cobblestone morphology, positive immunofluorescence staining for endothelial marker Factor VIII-associated antigen and fibronectin, and prominent Weibel-Palade bodies. The endothelial cells also exhibited other ultrastructural features characteristic of lymphatic endothelium, including sparse microvillous surface projections, overlapping intercellular junctions, and abundant intermediate filaments. This endothelial cell line represents a new source of proliferating lymphatic endothelium for future study, including structural and functional comparison to blood vascular endothelium. Supported in part by Arizona Disease Control Research Commission contracts 8277-000000-1-1-AT-6625 and ZB-7492. Presented in part at the 10th International Congress of Lymphology in Adelaide, Australia, August 1985.     

Genethics: project accountability via evaluation of teacher and student growth.

Accountability through demonstrated learning is increasingly being demanded by agencies funding science education projects. For example, the National Science Foundation requires evidence of the educational impact of programs designed to increase the scientific understanding and competencies of teachers and their students. The purpose of this paper is to share our human genetics educational experiences and accountability model with colleagues interested in serving the genetics educational needs of in-service secondary school science teachers and their students. Our accountability model is facilitated through (1) identifying the educational needs of the population of teachers to be served, (2) articulating goals and measurable objectives to meet these needs, and (3) then designing and implementing pretest/posttest questions to measure whether the objectives have been achieved. Comparison of entry and exit levels of performance on a 50-item test showed that teacher-participants learned a statistically significant amount of genetics content in our NSF-funded workshops. Teachers, in turn, administered a 25-item pretest/posttest to their secondary school students, and collective data from 121 classrooms across the United States revealed statistically significant increases in student knowledge of genetics content. Methods describing our attempts to evaluate teachers' use of pedagogical techniques and bioethical decision-making skills are briefly addressed.     

Antioxidants in sun and shade leaves of sour orange trees (Citrus aurantium) after long-term acclimation to elevated CO2

Antioxidative systems and the contents of pigments, malondialdehyde,soluble protein, and carbohydrate were investigated in sun-and shade-acclimated leaves of sour orange (Citrus aurantium)trees that had been grown for 7.5 years under ambient and elevated(+300 µmol mol^–1) atmospheric CO₂ concentrations.Sunacclimated leaves contained higher ascorbate, glutathioneand soluble carbohydrate contents and higher catalase activitiesthan shade-acclimated leaves. The activities of superoxide dismutases,which belonged to the family of Cu/Zn-isozymes, were similarin sunand shade-acclimated leaves and decreased in responseto enhanced CO₂. In shade-acclimated leaves, none of the otherparameters studied was affected by elevated CO₂. In sun-acclimatedleaves elevated CO₂ caused increases in carbohydrate and ascorbatecontents. There was no evidence for enhanced lipid peroxidationas assessed from the determination of the malondialdehyde contentsunder either conditions. Key words: Ascorbate, catalase, CO₂ enrichment, global change, glutathione, superoxide dismutase