Inoculation with native soil improves seedling survival and reduces non-native reinvasion in a grassland restoration

Losses of grasslands have been largely attributed to widespread land-use changes, such as conversion to row-crop agriculture. The remaining tallgrass prairie faces further losses due to biological invasions by non-native plant species, often with resultant ecosystem degradation. Of critical concern for conservation, restoration of native grasslands has been met with little success following eradication of non-native plants. In addition to the direct and indirect effects of non-native invasive plants on beneficial soil microbes, management practices targeting invasive species may also negatively affect subsequent restoration efforts. To assess mechanisms limiting germination and survival of native species and to improve native species establishment, we established six replicate plots of each of the following four treatments: (1) inoculated with freshly collected prairie soil with native seeds; (2) inoculated with steam-pasteurized soil with native seeds; (3) noninoculated with native seeds; or (4) noninoculated/nonseeded control. Inoculation with whole soil did not improve seed germination; however, addition of whole soil significantly improved native species survival, compared to pasteurized soil or noninoculated treatments. Inoculation with whole soil significantly decreased reestablishment of non-native invasive Bothriochloa bladhii (Caucasian bluestem); at the end of the growing season, plots receiving whole soil consisted of approximately 30% B. bladhii cover, compared to approximately 80% in plots receiving no soil inoculum. Our results suggest invasion and eradication efforts negatively affect arbuscular mycorrhizal hyphal and spore abundances and soil aggregate stability, and inoculation with locally adapted soil microbial communities can improve metrics of restoration success, including plant species richness and diversity, while decreasing reinvasion by non-native species.     

Canadian outpatients and advance directives: poor knowledge and little experience but positive attitudes.

OBJECTIVE: To examine the knowledge of, previous experience with, attitudes toward and perceived barriers to completing advance directives among outpatients at two general medicine clinics. DESIGN: Cross-sectional questionnaire administered in face-to-face structured interviews. SETTING: General internal-medicine outpatient clinics at a university teaching hospital. PATIENTS: One hundred and five adult outpatients who could communicate in spoken English and who consented to be interviewed. RESULTS: Of 167 patients approached, 58 were excluded because they could not communicate in spoken English, and 4 refused to participate. Of the remaining 105 patients, 17 (16%) knew about living wills, 12 (11%) about durable powers of attorney for health care and 4 (4%) about advance directives. Twenty-three (22%) had thought about their preferences for life-sustaining treatment, 20 (19%) had discussed them, none had written them down, and 45 (43%) had thought about choosing a proxy. Sixty-one (58%) wanted to think about their preferences for treatment, 65 (62%) wanted to discuss them, 32 (30%) wanted to write them down, and 80 (76%) wanted to choose a proxy. The perceived barriers to completing an advance directive were inability to write, the belief that an advance directive was unnecessary, a fatalistic attitude, previous discussion of preferences, a desire to leave the decision to doctors, uncertainty about preferences, a desire to discuss preferences rather than document them, a desire to wait until the situation arose, a desire to write down preferences in the future and a desire to avoid thinking about preferences or advance directives. Respondents with more knowledge of life-sustaining treatments were more likely to want to complete an advance directive. CONCLUSIONS: Outpatients have positive attitudes toward advance directives, but their knowledge and experience are limited. These data underscore the need for patient education and for policies to eliminate the barriers to completing advance directives that patients face.     

Expression of p21ras-related protein in the plasma and tissue of patients with adenomas and carcinomas of the colon

Over-expression of p21 ras-related protein was determined in the plasma by immunoblotting and in the tissue by immuno-histochemistry in a cohort of patients undergoing colonoscopy. In the plasma samples, p21 ras over-expression was detected in: 9% (4/47) of normal controls; 21% (13/61) of individuals with normal colonoscopies but with a prior history of colonic neoplasia; 12% (4/33) of small adenoma patients, 29% (6/21) of large adenoma patients; 63% (5/8) of carcinoma-in-adenoma patients; 50% (2/4) of Dukes' A carcinoma patients; and 20% (2/10) of Dukes' B-D carcinoma patients. In the tissue samples, p21 ras over-expression was detected in: 25% (2/8) of small adenoma patients; 44% (4/9) of large adenoma patients; 100% (4/4) of carcinoma-in-adenoma patients; and 33% (1/3) of Dukes' B-C carcinoma patients. For matched plasma-tissue pairs, there was a statistically significant correlation for p21 ras over-expression (R = 0.47, p = 0.02).     

In vivo growth stimulation of collagen gel embedded normal human and mouse primary mammary epithelial cells

A new system for studying growth of normal human mammary epithelial cells in an in vivo environment using athymic nude mice is described. Human mammary epithelial cells dissociated from reduction mammoplasty specimens were embedded within collagen gels and subsequently transplanted subcutaneously into nude mice. Histological sections of recovered collagen gels showed epithelial cells arranged as short tubules with some branching. Proliferation of mammary epithelial cells was quantitated in vivo by 3 days' continuous infusion with 5 bromo-2′-deoxy-uridine followed by immunostaining of sections from recovered gels. Ovarian steroids administered to the host animals, resulting in blood serum levels normally found in the human female, had little or no effect on the proliferation of human mammary epithelial cells. Collagen gel embedded mouse mammary epithelial cells, mouse mammary explants, and host mammary glands all responded similarly to ovarian steroids, suggesting that the unresponsiveness of the human mammary epithelial cells under these conditions was not due to dissociation per se. However, an increased dose of 17β-estradiol or a growth factor combination containing epidermal growth factor, cholera toxin, and cortisol significantly stimulated the proliferation of human outgrowths. The growth factor response was dependent on the location of the cells, with the greatest response seen in the part of the gel proximal to the osmotic pump delivering the growth factors and the effect gradually waning in area more distal to the pump. The effect was especially striking since the mitotic figures could be easily identified and the labeling index was as high as 75%. The host mouse mammary gland also responded to growth factors, resulting in ductal hyperplasia. The proliferative and morphogenetic effects of various agents on normal human mammary epithelial cells embedded in collagen gel can be studied in vivo in nude mice. © 1995 Wiley-Liss, Inc.     

β-Actin Messenger RNA Localization and Protein Synthesis Augment Cell Motility

In chicken embryo fibroblasts (CEFs), β-actin mRNA localizes near an actin-rich region of cytoplasm specialized for motility, the lamellipodia. This localization is mediated by isoform-specific 3′-untranslated sequences (zipcodes) and can be inhibited by antizipcode oligodeoxynucleotides (ODNs) (Kislauskis, E.H., X.-C. Zhu, and R.H. Singer. 1994. J. Cell Biol. 127: 441–451). This inhibition of β-actin mRNA localization resulted in the disruption of fibroblast polarity and, presumably, cell motility. To investigate the role of β-actin mRNA in motility, we correlated time-lapse images of moving CEFs with the distribution of β-actin mRNA in these cells. CEFs with localized β-actin mRNA moved significantly further over the same time period than did CEFs with nonlocalized mRNA. Antizipcode ODN treatment reduced this cell translocation while control ODN treatments showed no effect. The temporal relationship of β-actin mRNA localization to cell translocation was investigated using serum addition to serum-deprived cultures. β-actin mRNA was not localized in serum-deprived cells but became localized within minutes after serum addition (Latham, V.M., E.H. Kislauskis, R.H. Singer, and A.F. Ross. 1994. J. Cell Biol. 126:1211–1219). Cell translocation increased over the next 90 min, and actin synthesis likewise increased. Puromycin reduced this cell translocation and blocked this induction in cytosolic actin content. The serum induction of cell movement was also inhibited by antizipcode ODNs. These observations support the hypothesis that β-actin mRNA localization and consequent protein synthesis augment cell motility.     

Community participation in health care decision making: is it feasible?

Health care reform strategies proposed by provincial governments include decentralized funding and increased public participation in decision making. These proposals do not give details as to the public participation process, and a number of questions have been raised by the experience of some communities. Which citizens should form the decision-making group? What information do they need? What kinds of decisions should they make? What level of participation should they have? The results of a survey by Abelson and associates (see pages 403 to 412 of this issue) challenge the assumption that "communities" are willing to participate in health-care and social-service decision making. Willingness varied according to the composition of the groups polled, and participants'' support for traditional decision makers increased after the complexities of the decision-making process were discussed. However, whereas their study measured willingness to participate at one point in time only, experience gained from Ontario''s Better Beginnings, Better Futures project indicates that, given sufficient time, "ordinary" citizens are willing and can acquire the skills needed to decide how resources should be allocated for social services.     

An examination of the thresholds of enrichment: a resource-based growth model

A model of single-species growth in the chemostat on two non-reproducing, growth-limiting, noninhibitory, perfectly substitutable resources is considered. The medium in the growth vessel is enriched by increasing the input concentration of one of the resources. Analytical methods are used to determine the effects of enrichment on the asymptotic behaviour of the model for different dilution rates. It is shown that there exists a threshold value for the dilution rate which depends on the maximal growth rate of the species on each of the resources. Provided the dilution rate is below the threshold, enrichment is beneficial in the sense that the carrying capacity of the environment is increased, regardless of which resource is used to enrich the environment. When the dilution rate is increased beyond the threshold, it becomes important to consider which resource is used for enrichment. For one of the resources it is shown that, while moderate enrichment can be beneficial, sufficient enrichment leads to the extinction of the microbial population. For the other resource, enrichment leads from washout or initial condition dependent outcomes to survival, and is thus beneficial. There are important implications of these results to the management of natural aquatic ecosystems. For example, while enrichment may be beneficial to the microbial species during the summer months, it can lead to their decimation during spring run-off, when the natural dilution rate is higher.Research partially supported by an Ontario Graduate Scholarship. This author's contribution was motivated by results in her Ph.D. thesis at McMaster UniversityResearch supported by the National Sciences and Engineering Research Council of Canada.