Multiple paternity and mating group size in the European earwig,Forficula auricularia

1. The patterns of multiple paternity among the progeny of females are key properties of genetic mating systems. Female multiple mating should evolve due to direct or indirect benefits, but it may also partly be driven by the encounter rate with different potential mates. 2. In this study this hypothesis was experimentally tested in the European earwig (Forficula auricularia L.) by establishing experimental mating groups that differed in the number of males and females (i.e. density). The number of sires and mean sibling relatedness in each clutch were estimated using microsatellite‐based paternity analysis. 3. As predicted, the mean number of sires per clutch was significantly increased, and sibling relatedness decreased, in the higher density treatment where more potential male mates were available. This change was less than proportional to the number of males in the mating groups, indicating that mechanisms limiting multiple paternity in large mating groups were involved. There were no significant relationships between female reproductive success or male siring success with morphology (body size, weight, and forceps size). 4. The present results show that multiple paternity in F. auricularia clutches is partly determined by the availability of male mates and suggest that this effect is modulated by mechanisms in males and/or females that limit multiple paternity.     

Induction of a metabolic switch in insect cells by substrate-limited fed batch cultures

Insect cell metabolism was studied in substrate-limited fed batch cultures of Spodoptera frugiperda (Sf-9) cells. Results from a glucose-limited culture, a glutamine-limited culture, a culture limited in both glucose and glutamine and a batch culture were compared. A stringent relation between glucose excess and alanine formation was found. In contrast, glucose limitation induced ammonium formation, while, at the same time, alanine formation was completely suppressed. Simultaneous glucose and glutamine limitation suppressed both alanine and ammonium formation. Although the metabolism was influenced by substrate limitation, the specific growth rate was similar in all cultures. Alanine formation must involve incorporation of free ammonium, if ammonium formation is mediated by glutaminase and glutamate dehydrogenase, as our data suggest. On the basis of the results, two possible pathways for the formation of alanine in the intermediary metabolism in insect cells are suggested. The cellular yield on glucose was increased 6.6 times during glucose limitation, independently of the cellular yield on glutamine, which was increased 50–100 times during glutamine limitation. The results indicate that alanine overflow metabolism is energetically wasteful and that glutamine is a dispensable amino acid for cultured Sf-9 cells. Preliminary data confirm that glutamine can be synthesised by the cells themselves in amounts sufficient to support growth.     

Studien über die arbeitsteilung und die teilung des arbeitsgebietes bei der roten waldameise (Formica Rufa L.).

Ohne Zusammenfassung     

The ecological value of Eryngium horridum in maintaining biodiversity in subtropical grasslands

The role of facilitation in the structuring of plant communities has been often demonstrated in environments under high abiotic stress, especially in semi‐arid and arid ecosystems and high elevations. Few studies, however, analysed facilitation in systems that are highly productive and rich in species, which are thought to be theoretically unlikely to demonstrate strong effects of facilitation. Here, we investigate the importance of Eryngium horridum, a rosette species, on the maintenance of plant diversity in subtropical grasslands in southern Brazil. We evaluated facilitation in areas under two different types of management: abandonment and grazing. Plots were established in areas with and without individuals of E. horridum and all species were identified and had their cover estimated. The Relative Neighbour Effect index was calculated in order to verify the presence of competition or facilitation. Our results indicated facilitation in both abandoned and in grazed grasslands, but apparently through different mechanisms. In the first case, the plant's architecture opens the canopy and allows more light to reach small forbs in the grass matrix. In the second case, E. horridum appears to protect more palatable species from herbivores. Otherwise considered an obnoxious species, E. horridum plays an important ecological role in subtropical grasslands in southern Brazil by facilitating other species and consequently, increasing local richness. Areas with this rosette species are important sources of diaspores, which are able to colonize new open sites and thus, maintain biodiversity.     

The fate of phosphate under anoxic conditions in biological nutrient removal activated sludge systems

The nitrogen removal potential of phosphate accumulating organisms under anoxic conditions has been evaluated using a laboratory scale sequencing batch reactor fed with synthetic wastewater and operated in a sequence of anaerobic, anoxic and aerobic periods. The phosphate uptake rate under anoxic conditions was lower than that under aerobic conditions. However, in the presence of an external substrate such as glucose and acetate, the fate of phosphate was dependent on the substrate type; phosphate release occurred in the presence of nitrate as long as acetate was present and glucose did not cause any phosphate release. The nitrate uptake rate was also much lower with glucose than acetate. The results implied that poly-hydroxyalkanoates could be oxidized by nitrate and phosphate uptake during the anoxic phase should be introduced into process modeling. © Rapid Science Ltd. 1998     

Cd, Cu, Ni, Mn and Zn resistance and bioaccumulation by thermophilic bacteria, Geobacillus toebii subsp. decanicus and Geobacillus thermoleovorans subsp. stromboliensis

Bioaccumulation and heavy metal resistance of Cd²⁺, Cu²⁺, Ni²⁺, Zn²⁺ and Mn²⁺ ions by thermophilic Geobacillus toebii subsp. decanicus and Geobacillus thermoleovorans subsp. stromboliensis were investigated. The metal resistance from the most resistant to the most sensitive was found as Mn > Ni > Cu > Zn > Cd for both Geobacillus thermoleovorans subsp. stromboliensis and Geobacillus toebii subsp. decanicus. It was determined that the highest metal bioaccumulation was performed by Geobacillus toebii subsp. decanicus for Zn (36,496 μg/g dry weight cell), and the lowest metal bioaccumulation was performed by Geobacillus toebii subsp. decanicus for Ni (660.3 μg/g dry weight cell). Moreover, the dead cells were found to biosorbe more metal in their membranes compared to the live cells. In the presence of 7.32 mg/l Cd concentration, the levels of Cd absorbed in live and dead cell membranes were found as 17.44 and 46.2 mg/g membrane, respectively.     

Effect of chloroethene concentrations and granular activated carbon on reductive dechlorination rates and growth of Dehalococcoides spp

This study focused on the investigation of (i) the tetrachloroethene (PCE) toxicity threshold of a reductively dechlorinating mixed culture containing Dehalococcoides spp., (ii) the adsorption of PCE on different types of granular activated carbon (GAC), and (iii) the bioavailability and reductive dechlorination in the presence of GAC. The abundance of Dehalococcoides spp. detected by quantitative real-time polymerase chain reaction (qPCR) was found to increase by 2-4 orders of magnitude during degradation of PCE. No degradation occurred at dissolved concentrations beyond 420 μM (70 mg/L). Different adsorption isotherms were determined for thermally and chemically activated carbons. The addition of GAC to biological assays reduced the dissolved PCE concentration below the toxicity threshold. The combination of microbial reductive dechlorination with GAC adsorption proved to be a promising method for remediation of groundwater contaminated by high concentrations of chloroethenes.