Effects of nutrient enrichment on boreal streams: invertebrates, fungi and leaf-litter breakdown

1. The effect of nutrient enrichment on structural (invertebrate indices) and functional (leaf‐litter breakdown rates) characteristics of stream integrity was studied in nine boreal streams. 2. The results showed predicted changes in biotic indices and leaf‐litter breakdown along a complex (principal component) nutrient gradient. Biotic indices were better correlated with nutrient effects than leaf‐litter breakdown. 3. Fungal biomass and invertebrate densities in the litter bags were positively correlated with leaf‐litter breakdown, and both were also positively related to the nutrient gradient. 4. Invertebrate community composition influenced breakdown rate. High breakdown rates at one site were associated with the high abundance of the detritivore Asellus aquaticus. 5. This study lends support to the importance of invertebrate and fungi as mediators of leaf‐litter decomposition. However, our study also shows that study design (length of incubation) can confound the interpretation of nutrient‐induced effects on decomposition.     

Scientific Independence and Credibility in Sociopolitical Processes

Abstract: Absence of scientific independence can be associated with a lack of impartiality and therefore with a lack of credibility. Yet scientific credibility is essential for effective participation in sociopolitical processes—processes that necessarily involve politics and often result in decisions about land management, conservation, and public policy. All scientists are aware of these processes, many wish to participate, and some wish to advocate for their personal policy preferences. However, scientists who lack impartiality often create the perception of bias, and they can suffer a concomitant loss of credibility. Some policy-makers also have personal preferences for certain policies, and the term normative policies can be used here even though all policies can be viewed as normative in the sense that they involve multiple inputs. Hence, the idea that scientists must provide unbiased information for unbiased application by policy-makers is sometimes wrong. For scientists to be effective participants in sociopolitical processes that lead to conservation policies or related actions, they should inform the public about issues while avoiding direct involvement in policy development and the political considerations this necessarily entails. Scientists should only participate in the decision-making process with impartial information and in their proper role as objective scientists.     

RNA-dependent DNA Polymerase in Human Lymphocytes during Gene Activation by Phytohaemagglutinin

RNA-DEPENDENT. DNA polymerase an activity initially thought to be unique to RNA tumour viruses^1–3, is now known to be present in normal human lymphocytes⁴, which are differentiated and seldom divide in vivo or in culture. The addition of phytohaemagglutinin (PHA) or other mitogens (including appropriate antigens) transforms lymphocytes into actively proliferating cells⁵. Several enzymes which function in gene activation and DNA replication specifically increase in activity during this transformation^6,7. We now report that RNA-dependent DNA polymerase also behaves in this way.     

Relationships between host blood factors and proteases in Glossina morsitans subspecies infected with Trypanosoma congolense

Abstract. Host blood effects on Trypanosoma congolense establishment in Glossina morsitans morsitans and Glossina morsitans centralis were investigated using goat, rabbit, cow and rhinoceros blood. Meals containing goat erythrocytes facilitated infection in G. m. morsitans , whereas meals containing goat plasma facilitated infection in G. m. centralis. Goat blood effects were not observed in the presence of complementary rabbit blood components. N-acetyl-glucosamine (a midguMectin inhibitor) increased infection rates in some, but not all, blood manipulations. Cholesterol increased infection rates in G. m. centralis only. Both compounds together added to cow blood produced superinfection in G. m. centralis , but not in G. m. morsitans. Midgut protease levels did not differ 6 days post-infection in flies maintaining infections versus flies clearing infections. Protease levels were weakly correlated with patterns of infection, but only in G. m. morsitans. These results suggest that physiological mechanisms responsible for variation in infection rates are only superficially similar in these closely-related tsetse.