Effects of oxygen level on metabolism and development of seedlings of Trapa natans and two ecologically related species

Seeds of the water plant Trapa natans L. (water chestnut) can germinate in strict anoxia. The seedlings show seminal roots growing upwards while shoot buds remain quiescent until O₂ becomes available. Trapa seedlings are highly tolerant to anoxia. The rate of ethanol fermentation was 21.2 μmol (g FW)⁻¹ h⁻¹, while production of lactate was negligible and lower than that of succinate. The seminal root of Trapa compares better to the rice coleoptile rather than to the rice root, both functionally and as to the metabolic response to anoxia. The anaerobic germination of Nuphar luteum L. and Scirpus mucronatus L. was also characterized by a limited developmental program.     

Exploitation in the use of human subjects for medical experimentation: a re-examination of basic issues

Relatively subtle forms of exploitation of human subjects may arise from the inefficiency or incompetence of a researcher, from the existence of a power imbalance between principal and subject, or from the uneven distribution of research risks among various segments of the population. A powerful and knowledgeable person (or institution) may perpetrate the exploitation of an unempowered and ignorant individual even without intending to. There is an ethical burden on the former to protect the interests of the vulnerable. Excessive or insufficient compensation may be exploitative. However, genuine economic imperatives motivating needy volunteers have to be considered. These forms of exploitation should be appreciated in the context of social and cultural factors suggesting that the relationship between researcher and subject cannot properly be appraised as a contractual undertaking. While compliance with pertinent codes and regulations minimises the exploitative potential, they cannot be enforced in a way that does not recognize a society's peculiar characteristics. The experience with some Filipino cultural traits illustrates this point.     

Nutritive value of the nuña popping bean

Nuñas (Thaseolus vulgaris, Fabaceae), commonly called popping beans, are traditionally grown in the Andean highlands of South America, and are consumed as a snack food after a quick toasting process. Proximate analysis of their nutritive value revealed that nunas have a higher content of starch, amylose, and copper than four dry bean varieties and a lower mean content of protein, phosphorous, iron, and boron. The unique texture and taste of nuñas may be related to their high starch content. Antinutritional factors such as lectins were higher in raw and boiled nuña samples than in toasted nuñas, while tannin levels did not change from raw to toasted treatments. Overall in-vitro digestibility was slightly lower for toasted nunas than boiled dry bean.     

Nalidixic acid-resistant V79 cells with reduced DNA topoisomerase II activity and amplification prone phenotype.

Spontaneously nalidixic acid-resistant lines (NAr lines) were selected from a V79 Chinese hamster cell line and phenotypically characterized. NAr lines showed an increased doubling time, a higher number of spontaneous SCE, and more interestingly, decreased DNA topoisomerase II activity. These lines were also cross-resistant to the eukaryotic topoisomerase II inhibitors etoposide and adriamycin, but showed the same level of sensitivity as the parental line to the DNA topoisomerase I inhibitor camptothecin. NAr lines were cross-resistant to other drugs, such as PALA, MTX and MPA, resistance to which has been shown to arise by amplification of the target genes. This last feature, together with enhanced cross-resistance to PALA and MTX when employed simultaneously, suggests that NAr lines have an 'amplification prone' phenotype. From these results the decreased activity of topoisomerase II seems to be involved in the generation of amplified sequences possibly by affecting recombinational events underlying gene amplification.     

Human toxoplasmosis acquired by ingestion of goat's milk

Acute toxoplasmosis in three members of the same family was related to drinking unpasteurized goat's milk. The goats were reared, for milk production in a peri-domestic area. Based on indirect immunofluorescent reactions antibody titers greater than 1: 1024 were recorded in eight out of fifteen animals examined and were highest in the five lactating adult females. Toxoplasma was isolated, by inoculation of mice, from the milk of one of these females. Dogs reared in the same house showed no symptoms of acute toxoplasmosis and low antibody titers were detected in these animals. It was also found that the human infections could not have been due to the ingestion of food contaminated with oocysts.     

Effects of hydrogen peroxide on the content of major volatile halogenated compounds in the red alga <Emphasis Type="Italic">Asparagopsis taxiformis</Emphasis> (Bonnemaisoniaceae)

The genus Asparagopsis is a prolific source of halogenated metabolites. Due to its commercial applications, it has been intensively cultivated in southern Portugal. In the present study, we assess if the internal levels of the major halogenated metabolites (bromoform and dibromoacetic acid) in Asparagopsis taxiformis can be increased with hydrogen peroxide (H₂O₂) addition. Previous studies with red algae showed that the production/release of bromoform can be enhanced by exogenously supplying H₂O₂. However, no study has assessed if H₂O₂ supply enhances the content of secondary metabolites within the biomass. This detail is important as the objective of the proposed research is to enhance the content of these valuable metabolites in the produced biomass. Both the activity of the haloperoxidase enzyme and the metabolite content were assessed on short-term and long-term incubation periods to H₂O₂. To determine the susceptibility of A. taxiformis photosynthetic performance to the imposed oxidative stress, the in vivo fluorescence of photosystem II was monitored. A. taxiformis was shown to be physiologically vulnerable to H₂O₂, given the observed decrease of the maximum quantum yield of photosynthesis (F _v/F _m). Contrary to what was expected, the presence of H₂O₂ inhibited the activity of the iodoperoxidase enzyme. Nevertheless, the extracted halogenated metabolites were higher over the first hours of exposure to H₂O₂, decreasing after 48 h. These results are probably related to the prosthetic group of the halogenated enzyme in A. taxiformis and the long-term oxidative stress damage of H₂O₂ exposure. Considering the objective of the proposed research, addition of H₂O₂ to the cultures, prior (3 h) to biomass harvesting, increases the metabolite content.     

Turnover and trends in butterfly communities on two British tidal islands: stochastic influences and deterministic factors

Aim Community trends were investigated for two small islands and two local mainland butterfly communities within the UK over a period of 20–30 years. Location Hilbre Island off the Wirral Peninsula at 53.33° N, 3.10° W; Lindisfarne, an island off the Northumberland coast at 56.41° N, 1.48° W; Leighton Moss at 54.08° N, 2.26° W; Wyre Forest at 52.23° N, 2.14° W, UK. Methods Butterfly species data were collected on Hilbre and two mainland sites (Leighton Moss and Wyre Forest) from 1983 to 2006, and on Lindisfarne from 1977 to 2006, as part of the National Habitat Survey, the UK Butterfly Monitoring Scheme and ‘Butterflies for the New Millennium Atlas’ recording. Matrices of associations (Sokal and Michener’s matching coefficient S_SM; resemblance coefficient) were computed between years and subject to non‐metric multidimensional scaling (NMDS) and Mantel tests. The pattern of extinctions and colonizations at sites were examined, their heterogeneity tested by applying a Friedman test to fractional incidences for the same years. Regression analysis (multiple regression and logit regression) was used to relate butterfly numbers and incidences to climate variables, time and previous records. Results Significant community trends based on population counts and species’ incidences were found for all four sites. There was a significant climatic signal for Hilbre; although this was not apparent for the remaining sites, significant associations occurred between records for a number of species and climatic variables at all sites. Substantial turnover of species on the islands was inversely related to numbers of records for species but not to their conspicuousness to recorders. Main conclusions We argue that time trends are widespread in butterfly communities, even for relatively short periods; they are largely generated by stochastic influences rather than by more substantive factors such as climate change. Potential biases in surveying and recording history are shown to be unlikely. A clear climate signal was found only for the small Hilbre Island, for which there was also evidence for the significant influence of colonization capability of individual source species. We conclude that for many species, small islands will be sinks or pseudosinks and their ‘populations’ vulnerable to small changes in source–sink dynamics.