Insulin secretion and (pro)insulin biosynthesis of cultured mice islets after glibenclamide loading in vitro

Summary Isolated islets from C57B1/6J mice exposed to 10 mmoles/1 glucose supplemented with 5 g/ml glibenclamide for 48 h released significantly less insulin in the subsequent short-time incubation thanuntreated controls (without glibenclamide), whereas insulin biosynthesis was not suppressed by glibenclamide treatment.Investigations were carried out as a part of the ForschungsprojektDiabetes mellitus und Fettstoffwechselstörungen, supported by the Ministry of Health of the GDR.     

Perennial water ice identified in the south polar cap of Mars

The inventory of water and carbon dioxide reservoirs on Mars are important clues for understanding the geological, climatic and potentially exobiological evolution of the planet. From the early mapping observation of the permanent ice caps on the martian poles, the northern cap was believed to be mainly composed of water ice, whereas the southern cap was thought to be constituted of carbon dioxide ice. However, recent missions (NASA missions Mars Global Surveyor and Odyssey) have revealed surface structures, altimetry profiles, underlying buried hydrogen, and temperatures of the south polar regions that are thermodynamically consistent with a mixture of surface water ice and carbon dioxide. Here we present the first direct identification and mapping of both carbon dioxide and water ice in the martian high southern latitudes, at a resolution of 2 km, during the local summer, when the extent of the polar ice is at its minimum. We observe that this south polar cap contains perennial water ice in extended areas: as a small admixture to carbon dioxide in the bright regions; associated with dust, without carbon dioxide, at the edges of this bright cap; and, unexpectedly, in large areas tens of kilometres away from the bright cap.     

Taxonomy Based Models for Reasoning: Making Inferences from Electronic Road Sign Information

Taxonomy Based modeling was applied to describe drivers’ mental models of variable message signs (VMS’s) displayed on expressways. Progress in road telematics has made it possible to introduce variable message signs (VMS’s). Sensors embedded in the carriageway every 500m record certain variables (speed, flow rate, etc.) that are transformed in real time into “driving times” to a given destination if road conditions do not change. VMS systems are auto-regulative Man-Machine (AMMI) systems which incorporate a model of the user: if the traffic flow is too high, then drivers should choose alternative routes. In so doing, the traffic flow should decrease. The model of the user is based on suppositions such as: people do not like to waste time, they fully understand the displayed messages, they trust the displayed values, they know of alternative routes. However, people also have a model of the way the system functions. And if they do not believe the contents of the message, they will not act as expected. We collected data through interviews with drivers using the critical incidents technique (Flanagan, 1985). Results show that the mental models that drivers have of the way the VMS system works are various but not numerous and that most of them differ from the“ideal expert” mental model. It is clear that users don’t have an adequate model of how the VMS system works and that VMS planners have a model of user behaviour that does not correspond to the behaviour of the drivers we interviewed. Finally, Taxonomy Based Modeling is discussed as a tool for mental model remediation.     

Mutations in RNF135, a gene within the NF1 microdeletion region, cause phenotypic abnormalities including overgrowth

17q11 microdeletions that encompass NF1 cause 5%-10% of cases of neurofibromatosis type 1, and individuals with microdeletions are typically taller than individuals with intragenic NF1 mutations, suggesting that deletion of a neighboring gene might promote human growth. We identified mutations in RNF135, which is within the NF1 microdeletion region, in six families characterized by overgrowth, learning disability, dysmorphic features and variable additional features. These data identify RNF135 as causative of a new overgrowth syndrome and demonstrate that RNF135 haploinsufficiency contributes to the phenotype of NF1 microdeletion cases.     

Ancient co-speciation of simian foamy viruses and primates

Although parasite-host co-speciation is a long-held hypothesis, convincing evidence for long-term co-speciation remains elusive, largely because of small numbers of hosts and parasites studied and uncertainty over rates of evolutionary change. Co-speciation is especially rare in RNA viruses, in which cross-species transfer is the dominant mode of evolution. Simian foamy viruses (SFVs) are ubiquitous, non-pathogenic retroviruses that infect all primates. Here we test the co-speciation hypothesis in SFVs and their primate hosts by comparing the phylogenies of SFV polymerase and mitochondrial cytochrome oxidase subunit II from African and Asian monkeys and apes. The phylogenetic trees were remarkably congruent in both branching order and divergence times, strongly supporting co-speciation. Molecular clock calibrations revealed an extremely low rate of SFV evolution, 1.7 x 10(-8) substitutions per site per year, making it the slowest-evolving RNA virus documented so far. These results indicate that SFVs might have co-speciated with Old World primates for at least 30 million years, making them the oldest known vertebrate RNA viruses.     

A young source for the Hawaiian plume

Recycling of oceanic crust through subduction, mantle upwelling, and remelting in mantle plumes is a widely accepted mechanism to explain ocean island volcanism. The timescale of this recycling is important to our understanding of mantle circulation rates. Correlations of uranogenic lead isotopes in lavas from ocean islands such as Hawaii or Iceland, when interpreted as model isochrons, have yielded source differentiation ages between 1 and 2.5?billion years (Gyr). However, if such correlations are produced by mixing of unrelated mantle components they will have no direct age significance. Re-Os decay model ages take into account the mixing of sources with different histories, but they depend on the assumed initial Re/Os ratio of the subducted crust, which is poorly constrained because of the high mobility of rhenium during subduction. Here we report the first data on (87)Sr/(86)Sr ratios for 138 melt inclusions in olivine phenocrysts from lavas of Mauna Loa shield volcano, Hawaii, indicating enormous mantle source heterogeneity. We show that highly radiogenic strontium in severely rubidium-depleted melt inclusions matches the isotopic composition of 200-650-Myr-old sea water. We infer that such sea water must have contaminated the Mauna Loa source rock, before subduction, imparting a unique 'time stamp' on this source. Small amounts of seawater-derived strontium in plume sources may be common but can be identified clearly only in ultra-depleted melts originating from generally highly (incompatible-element) depleted source components. The presence of 200-650-Myr-old oceanic crust in the source of Hawaiian lavas implies a timescale of general mantle circulation with an average rate of about 2 (±1)?cm?yr(-1), much faster than previously thought.