THE WORLD WAR II PLUTONIUM EXPERIMENTS: CONTESTED STORIES AND THEIR LESSONS FOR MEDICAL RESEARCH AND INFORMED CONSENT

During the Second World War medical researchers around the USAinjected 18 hospital patients with radioactive plutonium in orderto learn its effects on the body. Two documents, a newspaperaccount and a university committee report, tell divergent storiesof the scientists and patients involved in that experiment. Thisarticle uses those documents – plutonium narratives– as a catalyst for exploring the problematicrepresentation of past human experimentation, assumptions of moralprogress in medical research, and the nature of informed consenttoday. Informed consent is shown to be an evolving process anddiscursive practice that cannot be understood apart from itshistorical and cultural embeddedness.     

Gel electrophoresis studies of proteins from leaves of photoperiodically induced and vegetative cocklebur plants

Comparisons of proteins synthesized in photoperiodically-sensitiveleaves of induced and vegetative cocklebur plants were made.Fifteen or more protein bands could be separated by polyacrylamidegel electrophoresis when polyvinylpyrrolidone was used in theextracting buffer to remove phenolics. As contrasted to resultsof others with Pharbilis nil, no differences in stained bandingpatterns could be detected in vegetative and induced plants.Radioactive leucine, lysine and phenylalanine were incorporatedinto similar leaf proteins during the last half of an inductivedark period. These experiments and dual-labeling studies with³H- and ¹⁴C-phenylalanine indicated no consistent differencesin the types of extracted proteins synthesized by leaves ofvegetative and induced plants. ¹Present address: Plant Science Dept., Utah State University,Logan 84321, U.S.A. (Received October 26, 1970; )     

Hydroperiod,predators and the distribution of physid snails across the freshwater habitat gradient

1. Studies of species distributions across environmental gradients further our understanding of mechanisms regulating species diversity at the landscape scale. For some freshwater taxa the habitat gradient from small, shallow and temporary ponds to large, deep and permanent lakes has been shown to be an important environmental axis. Freshwater snails are key players in freshwater ecosystems, but there are no comprehensive studies of their distributions across the entire freshwater habitat gradient. Here we test the hypothesis that snail species in the family Physidae are distributed in a non‐random manner across the habitat gradient. We sampled the snails, their predators and the abiotic environment of 61 ponds and lakes, spanning a wide range in depth and hydroperiod. 2. Temporary habitats had the lowest biomass of predators. Shallow permanent ponds had the highest biomass of invertebrate predators but an intermediate fish biomass. Deep ponds and lakes had the highest fish biomass and intermediate invertebrate biomass. Five species of physids occurred in the regional species pool and 60 of the 61 ponds and lakes surveyed contained physid snails. Each pond and lake contained an average of just 1.2 physid species, illustrating limited membership in local communities and substantial among‐site heterogeneity in species composition. 3. Physids showed strong sorting along the habitat gradient, with Physa vernalis found in the shortest hydroperiod ponds and Aplexa elongata, P. gyrina, P. acuta and P. ancillaria found in habitats of successively greater permanence. When organised into a site‐by‐species incidence matrix with sites ordered according to their hydroperiods, we found the pattern of incidence to be highly coherent, showing that much of the heterogeneity in species composition from one pond to another is explained by hydroperiod. We also found that the number of species replacements along this gradient was higher than random, showing that replacement is more important than nesting in describing species composition in ponds of different hydroperiod. 4. Discriminant analysis showed that pond depth, invertebrate biomass and fish biomass were the best predictors of species composition. Analysis of these niche dimensions showed that P. vernalis and A. elongata were most successful in shallow, temporary ponds with few predators. P. gyrina and P. acuta were typically found in ponds of intermediate depth and high predator abundance. P. ancillaria was found in the deepest lakes, which had abundant fish predators but few invertebrate predators. Of the five species considered, P. ancillaria, P. vernalis and A. elongata were relatively specialised with regard to key habitat characteristics, P. gyrina was moderately generalised and P. acuta was remarkably generalised, since it alone occurred across the entire freshwater habitat gradient. The exceptional habitat breadth of P. acuta stands in contrast to distributional studies of other freshwater taxa and deserves further attention.     

Immediate Struggles: People, Power, and Place in Rural Spain

Immediate Struggles: People, Power, and Place in Rural Spain . Susana Narotzky and Gavin Smith. Berkeley: University of California Press, 2006. 250 pp.     

An information-theoretical approach to phylogeography

Data analysis in phylogeographic investigations is typically conducted in either a qualitative manner, or alternatively via the testing of null hypotheses. The former, where inferences about population processes are derived from geographical patterns of genetic variation, may be subject to confirmation bias and prone to overinterpretation. Testing the predictions of null hypotheses is arguably less prone to bias than qualitative approaches, but only if the tested hypotheses are biologically meaningful. As it is difficult to know a priori if this is the case, there is the general need for additional methodological approaches in phylogeographic research. Here, we explore an alternative method for analysing phylogeographic data that utilizes information theory to quantify the probability of multiple hypotheses given the data. We accomplish this by augmenting the model‐selection procedure implemented in ima with calculations of Akaike Information Criterion scores and model probabilities. We generate a ranking of 17 models each representing a set of historical evolutionary processes that may have contributed to the evolution of Plethodon idahoensis, and then quantify the relative strength of support for each hypothesis given the data using metrics borrowed from information theory. Our results suggest that two models have high probability given the data. Each of these models includes population divergence and estimates of ancestral θ that differ from estimates of descendent θ, inferences consistent with prior work in this system. However, the models disagree in that one includes migration as a parameter and one does not, suggesting that there are two regions of parameter space that produce model likelihoods that are similar in magnitude given our data. Results of a simulation study suggest that when data are simulated with migration, most of the optimal models include migration as a parameter, and further that when all of the shared polymorphism results from incomplete lineage sorting, most of the optimal models do not. The results could also indicate a lack of precision, which may be a product of the amount of data that we have collected. In any case, the information‐theoretic metrics that we have applied to the analysis of our data are statistically rigorous, as are hypothesis‐testing approaches, but move beyond the ‘reject/fail to reject’ dichotomy of conventional hypothesis testing in a manner that provides considerably more flexibility to researchers.     

Maintenance of genetic variation in plants and pathogens involves complex networks of gene-for-gene interactions

The RPP13 [recognition of Hyaloperonospora arabidopsidis (previously known as Peronospora parasitica )] resistance ( R ) gene in Arabidopsis thaliana exhibits the highest reported level of sequence diversity among known R genes. Consistent with a co-evolutionary model, the matching effector protein ATR13 ( A. thaliana -recognized) from H. arabidopsidis reveals extreme levels of allelic diversity. We isolated 23 new RPP13 sequences from a UK metapopulation, giving a total of 47 when combined with previous studies. We used these in functional studies of the A. thaliana accessions for their resistance response to 16 isolates of H. arabidopsidis . We characterized the molecular basis of recognition by the expression of the corresponding ATR13 genes from these 16 isolates in these host accessions. This allowed the determination of which alleles of RPP13 were responsible for pathogen recognition and whether recognition was dependent on the RPP13/ATR13 combination. Linking our functional studies with phylogenetic analysis, we determined that: (i) the recognition of ATR13 is mediated by alleles in just a single RPP13 clade; (ii) RPP13 alleles in other clades have evolved the ability to detect other pathogen ATR protein(s); and (iii) at least one gene, unlinked to RPP13 in A. thaliana, detects a different subgroup of ATR13 alleles.     

Accumulation of DNA damage in Antarctic mosses: correlations with ultraviolet-B radiation, temperature and turf water content vary among species

The susceptibility of three East Antarctic moss species to UV-B radiation was examined by measuring accumulation of cyclobutane pyrimidine dimers under natural sunlight during the austral summer season of 2002/03. The 2002/03 season was characterized by unusually low springtime ozone depletion and as such our results likely underestimate the DNA damage possible in a more typical UV-B radiation season. Despite this all three species accumulated significant DNA photoproducts. We also found a positive association between photoproduct accumulation and incident UV-B radiation in the two cosmopolitan species, Bryum pseudotriquetrum and Ceratodon purpureus , with more DNA damage in samples collected early in the season compared with later in the summer. For B. pseudotriquetrum , negative associations were also observed between photoproduct accumulation and both turf water content and the 10-day mean air temperature. Photoproduct accumulation in the endemic species Schistidium antarctici was similarly high across the season and no significant association with environmental variables was found. Our results are consistent with the two cosmopolitan species having somewhat higher UV-B-screening capabilities and possibly more efficient mechanisms for repairing DNA damage than the endemic S. antarctici .