Cadmium Tolerance and Accumulation in Indian Mustard Is Enhanced by Overexpressing γ-Glutamylcysteine Synthetase

To investigate rate-limiting factors for glutathione and phytochelatin (PC) production and the importance of these compounds for heavy metal tolerance, Indian mustard (Brassica juncea) was genetically engineered to overexpress the Escherichia coli gshI gene encoding γ-glutamylcysteine synthetase (γ-ECS), targeted to the plastids. The γ-ECS transgenic seedlings showed increased tolerance to Cd and had higher concentrations of PCs, γ-GluCys, glutathione, and total non-protein thiols compared with wild-type (WT) seedlings. When tested in a hydroponic system, γ-ECS mature plants accumulated more Cd than WT plants: shoot Cd concentrations were 40% to 90% higher. In spite of their higher tissue Cd concentration, the γ-ECS plants grew better in the presence of Cd than WT. We conclude that overexpression of γ-ECS increases biosynthesis of glutathione and PCs, which in turn enhances Cd tolerance and accumulation. Thus, overexpression of γ-ECS appears to be a promising strategy for the production of plants with superior heavy metal phytoremediation capacity.     

The influence of climatic seasonality on the diversity of different tropical pollinator groups

Tropical South America is rich in different groups of pollinators, but the biotic and abiotic factors determining the geographical distribution of their species richness are poorly understood. We analyzed the species richness of three groups of pollinators (bees and wasps, butterflies, hummingbirds) in six tropical forests in the Bolivian lowlands along a gradient of climatic seasonality and precipitation ranging from 410 mm to 6250 mm. At each site, we sampled the three pollinator groups and their food plants twice for 16 days in both the dry and rainy seasons. The richness of the pollinator groups was related to climatic factors by linear regressions. Differences in species numbers between pollinator groups were analyzed by Wilcoxon tests for matched pairs and the proportion in species numbers between pollinator groups by correlation analyses. Species richness of hummingbirds was most closely correlated to the continuous availability of food, that of bees and wasps to the number of food plant species and flowers, and that of butterflies to air temperature. Only the species number of butterflies differed significantly between seasons. We were not able to find shifts in the proportion of species numbers of the different groups of pollinators along the study gradient. Thus, we conclude that the diversity of pollinator guilds is determined by group-specific factors and that the constant proportions in species numbers of the different pollinator groups constitute a general pattern.     

The MIPS mammalian protein-protein interaction database

SUMMARY: The MIPS mammalian protein-protein interaction database (MPPI) is a new resource of high-quality experimental protein interaction data in mammals. The content is based on published experimental evidence that has been processed by human expert curators. We provide the full dataset for download and a flexible and powerful web interface for users with various requirements.     

Minos as a genetic and genomic tool in Drosophila melanogaster

Much of the information about the function of D. melanogaster genes has come from P-element mutagenesis. The major drawback of the P element, however, is its strong bias for insertion into some genes (hotspots) and against insertion into others (coldspots). Within genes, 5′-UTRs are preferential targets. For the successful completion of the Drosophila Genome Disruption Project, the use of transposon vectors other than P will be necessary. We examined here the suitability of the Minos element from Drosophila hydei as a tool for Drosophila genomics. Previous work has shown that Minos, a member of the Tc1/mariner family of transposable elements, is active in diverse organisms and cultured cells; it produces stable integrants in the germ line of several insect species, in the mouse, and in human cells. We generated and analyzed 96 Minos integrations into the Drosophila genome and devised an efficient “jump-starting” scheme for production of single insertions. The ratio of insertions into genes vs. intergenic DNA is consistent with a random distribution. Within genes, there is a statistically significant preference for insertion into introns rather than into exons. About 30% of all insertions were in introns and ~55% of insertions were into or next to genes that have so far not been hit by the P element. The insertion sites exhibit, in contrast to other transposons, little sequence requirement beyond the TA dinucleotide insertion target. We further demonstrate that induced remobilization of Minos insertions can delete nearby sequences. Our results suggest that Minos is a useful tool complementing the P element for insertional mutagenesis and genomic analysis in Drosophila.     

Association of protein biogenesis factors at the yeast ribosomal tunnel exit is affected by the translational status and nascent polypeptide sequence

Ribosome-associated protein biogenesis factors (RPBs) act during a short but critical period of protein biogenesis. The action of RPBs starts as soon as a nascent polypeptide becomes accessible from the outside of the ribosome and ends upon termination of translation. In yeast, RPBs include the chaperones Ssb1/2 and ribosome-associated complex, signal recognition particle, nascent polypeptide-associated complex (NAC), the aminopeptidases Map1 and Map2, and the Nalpha-terminal acetyltransferase NatA. Here, we provide the first comprehensive analysis of RPB binding at the yeast ribosomal tunnel exit as a function of translational status and polypeptide sequence. We measured the ratios of RPBs to ribosomes in yeast cells and determined RPB occupation of translating and non-translating ribosomes. The combined results imply a requirement for dynamic and coordinated interactions at the tunnel exit. Exclusively, NAC was associated with the majority of ribosomes regardless of their translational status. All other RPBs occupied only ribosomal subpopulations, binding with increased apparent affinity to randomly translating ribosomes as compared with non-translating ones. Analysis of RPB interaction with homogenous ribosome populations engaged in the translation of specific nascent polypeptides revealed that the affinities of Ssb1/2, NAC, and, as expected, signal recognition particle, were influenced by the amino acid sequence of the nascent polypeptide. Complementary cross-linking data suggest that not only affinity of RPBs to the ribosome but also positioning can be influenced in a nascent polypeptide-dependent manner.     

Governance options for science–policy interfaces on biodiversity and ecosystem services: comparing a network versus a platform approach

Science–policy-interfaces (SPIs) are expected to go beyond the linear model of scientific policy advice through creating spaces for exchange and dialogue between ‘policy’ and ‘knowledge’. Given that most environmental issues require inter- and transdisciplinary approaches, SPIs must take into account a variety of knowledge types, views and interests of scientists, policymakers and other decision makers. Moreover, acceptance and durability of SPIs depend largely on their perceived legitimacy and the credibility of their knowledge-gathering processes, providing additional challenges for their internal organisation. As the interplay between different knowledge types and decision making is far from neutral, a reflexive approach is required in the design of an SPI so that it is capable of learning from past experiences. The aim of this article is to discuss which governance arrangements could best support the development of an effective and legitimate SPI for European biodiversity politics. We analyse different options for facilitating the implementation of a ‘Network of Knowledge’ approach. This approach has been developed to improve the interface between diverse knowledge-holder communities and decision making processes for biodiversity and ecosystem services—a field where multi-scalar and multi-dimensional problems arise. In this article, we develop and discuss two stylized extreme governance models as our starting point: an `informal network model´, which almost entirely depends on the dedication of individuals, versus a more formalized `platform model´, predominantly based on the needs and interests of the organisations involved. We discuss the pros and cons of each of these models in reaching their objectives and in developing sound governing processes for a ‘Network of Knowledge’. From this discussion, we derive a recommended design for the reflexive governance of such a network in the context of the European Union and finish by discussing some more general lessons learnt.