Trophic flexibility and opportunism in pike Esox lucius

The first comprehensive investigation of pike Esox lucius trophic ecology in a region (Ireland) where they have long been thought to be a non‐native species is presented. Diet was investigated across habitat types (lake, river and canal) through the combined methods of stable‐isotope and stomach content analyses. Variations in niche size, specialization and the timing of the ontogenetic dietary switch were examined, revealing pronounced opportunism and feeding plasticity in E. lucius, along with a high occurrence of invertivory (up to 60 cm fork length, L_F) and a concomitant delayed switch to piscivory. Furthermore, E. lucius were found to primarily prey upon the highly available non‐native roach Rutilus rutilus, which may alleviate predation pressure on brown trout Salmo trutta, highlighting the complexity of dynamic systems and the essential role of research in informing effective management.     

Ecological indicators of fruit and vegetable consumption (EIFVCs): A case study

Food and drink consumption was found to be responsible for around 20–30% of environmental impacts. Environmental impacts occur during all stages of the food production chain. However, households influence these impacts with through their choice of diet and habits, thus directly affecting the environment through food-related energy consumption and waste generation. With the multiplication of local policies for sustainable consumption, it has become increasingly useful to gather information on the evolution of the ecological impacts associated with household food consumption. Dealing with the indicators of household consumption of fruits and vegetables will enable changes in the population's lifestyles and the effectiveness of local policies to be monitored.The aims of this article are twofold: to provide a conceptual framework on the purposes of ecological indicators of fruit and vegetable consumption (EIFVCs) and to provide a methodological approach for selecting and measuring the most relevant EIFVCs at a local scale. Considering the great diversity of ecological impacts, the large number of potential EIFVCs must be reduced to obtain fewer EIFVCs, but that are relevant at local scale. To be relevant, the EIFVCs must provide information on the three phases of consumption (acquisition, use, and disposal) and on the upstream and downstream phases of the consumption process; they should evaluate the more problematic ecological impacts at the local scale (level of concern); and they have to only point out the ecological impacts that households can significantly reduce through their consumption rates. To measure relevant EIFVCs, three approaches must be combined: monitoring the ecological impacts, measuring the material and energy fluxes associated with household consumption, and analysing the consumer behaviours that result in the observed ecological impacts.As an illustration, the methodology is applied to the Bordeaux Metropolitan Area (France). In this area, eleven EIFVCs seem relevant. The use of surveys characterises all eleven of the EIFVCs, despite the difficulty of establishing quantified relationships between household behaviours and measured ecological impacts. The measuring of fluxes is possible for eight of them, whereas the monitoring of ecological impacts is only feasible for two of them.     

Local hopping mobile DNA implicated in pseudogene formation and reductive evolution in an obligate cyanobacteria-plant symbiosis

Background

Insertion sequences (ISs) are approximately 1 kbp long “jumping” genes found in prokaryotes. ISs encode the protein Transposase, which facilitates the excision and reinsertion of ISs in genomes, making these sequences a type of class I (“cut-and-paste”) Mobile Genetic Elements. ISs are proposed to be involved in the reductive evolution of symbiotic prokaryotes. Our previous sequencing of the genome of the cyanobacterium ‘Nostoc azollae’ 0708, living in a tight perpetual symbiotic association with a plant (the water fern Azolla), revealed the presence of an eroding genome, with a high number of insertion sequences (ISs) together with an unprecedented large proportion of pseudogenes. To investigate the role of ISs in the reductive evolution of ‘Nostoc azollae’ 0708, and potentially in the formation of pseudogenes, a bioinformatic investigation of the IS identities and positions in 47 cyanobacterial genomes was conducted. To widen the scope, the IS contents were analysed qualitatively and quantitatively in 20 other genomes representing both free-living and symbiotic bacteria.

Results

Insertion Sequences were not randomly distributed in the bacterial genomes and were found to transpose short distances from their original location (“local hopping”) and pseudogenes were enriched in the vicinity of IS elements. In general, symbiotic organisms showed higher densities of IS elements and pseudogenes than non-symbiotic bacteria. A total of 1108 distinct repeated sequences over 500 bp were identified in the 67 genomes investigated. In the genome of ‘Nostoc azollae’ 0708, IS elements were apparent at 970 locations (14.3%), with 428 being full-length. Morphologically complex cyanobacteria with large genomes showed higher frequencies of IS elements, irrespective of life style.

Conclusions

The apparent co-location of IS elements and pseudogenes found in prokaryotic genomes implies earlier IS transpositions into genes. As transpositions tend to be local rather than genome wide this likely explains the proximity between IS elements and pseudogenes. These findings suggest that ISs facilitate the reductive evolution in for instance in the symbiotic cyanobacterium ‘Nostoc azollae’ 0708 and in other obligate prokaryotic symbionts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1386-7) contains supplementary material, which is available to authorized users.     

Allometric variation among juvenile, adult male and female eastern bearded dragons Pogona barbata (Cuvier, 1829), with comments on the behavioural implications

The functional significance of allometric change in reptiles has received limited attention and the reason for such changes has been regarded as ‘obscure’. In this paper we report data on the Australian Pogona barbata, the eastern bearded dragon, from across their range and review changes in allometric growth among juveniles, and adult males and females and consider the functional relevance of these changes. There were significant differences in the population for mass, tail length, tail width, rear leg length and jaw length. These differences were consistent with differences required in locomotor performance and thus habitat use, together with access to different preferred dietary components.     

The structure of human ubiquitin in 2-methyl-2,4-pentanediol: a new conformational switch

A new crystal structure of human ubiquitin is reported at 1.8 Å resolution. Compared with the other known crystal structure or the solution NMR structure of monomeric human ubiquitin, this new structure is similar in its overall fold but differs with respect to the conformation of the backbone in a surface‐exposed region. The conformation reported here resembles conformations previously seen in complex with deubiquinating enzymes, wherein the Asp52/Gly53 main chain and Glu24 side chain move. This movement exposes the backbone carbonyl of Asp52 to the exterior of the molecule, making it possible to engage in hydrogen‐bond contacts with neighboring molecules, rather than in an internal hydrogen bond with the backbone of Glu24. This particular crystal form of ubiquitin has been used in a large number of solid state NMR studies. The structure described here elucidates the origin of many of the chemical shift differences comparing solution and solid state studies.     

氨溴索与碳酸氢钠序贯灌洗佐治支气管扩张感染疗效分析

目的探讨氨溴索与碳酸氢钠灌洗治疗支气管扩张反复感染的疗效及意义。方法将支气管扩张反复感染住院患者,分为灌洗组(常规治疗方法 +支气管局部注药灌洗34例)、对照组(常规治疗方法 38例),治疗2周后进行临床评估,随访半年。结果灌洗组总有效率与对照组相比差异有统计学意义(P<0.05),半年急性加重次数与对照组相比差异有统计学意义(P<0.01)。结论在常规治疗基础上局部氨溴索、碳酸氢钠序贯灌洗能提高支气管扩张感染疗效、减少半年急性加重次数、改善生活质量,通过改善微环境来维持菌群平衡值得借鉴、推广。     

Infestation of commercial bumblebee (Bombus impatiens) field colonies by small hive beetles (Aethina tumida)

Abstract.  1. The small hive beetle, Aethina tumida , is a parasite of honeybee ( Apis mellifera ) colonies native to sub-Saharan Africa and has become an invasive species. In North America the beetle is now sympatric with bumblebees, Bombus , not occurring in its native range. Laboratory studies have shown that small hive beetles can reproduce in bumblebee colonies but it was not known whether infestations occur in the field.
2. For the first time, infestation of bumblebee colonies by small hive beetles was investigated in the field. Commercial Bombus impatiens colonies ( n = 10) were installed in proximity to infested apiaries. Within 8 weeks, all colonies that were alive in the 5-week observation period ( n = 9) became naturally infested with adult small hive beetles and successful small hive beetle reproduction occurred in five colonies.
3. In four-square choice tests, the beetles were attracted to both adult bumblebee workers and pollen from bumblebee nests, suggesting that these odours may serve as cues for host finding.
4. The data indicate that bumblebee colonies may serve as alternative hosts for small hive beetles in the field. To foster the conservation of these essential native pollinators, investigations on the actual impact of small hive beetles on wild bumblebee populations are suggested.     

Apartment electrical wiring: a cause of extremely low frequency magnetic field exposure in residential areas

Extremely low frequency (ELF) magnetic fields (MFs) were measured at 696 points in a room of a Japanese apartment building. The building had 124 rooms with layouts and wiring identical to those of the studied room. ELF-MFs exceeded 0.4 microT in 24% of the living space, and the maximum value, 1.8 microT, was detected at floor level. Analysis of the MF distribution revealed that 60 Hz 100 V electrical wiring for room lights within the floor and ceiling had been laid out in large rectangles, equivalent to 1 turn coils. Further plotting of the vertical components every 0.01 m on the floor indicated that the depth of the cable was 0.23 m. Further studies should be conducted in order to confirm that the building investigated in this pilot study is typical of Japanese apartment buildings in terms of ELF-MFs.     

Evolution of extraordinary female-biased sex ratios: the optimal schedule of sex ratio in local mate competition

Female-biased sex ratio in local mate competition has been well studied both theoretically and experimentally. However, some experimental data show more female-biased sex ratios than the theoretical predictions by Hamilton [1967. Science 156, 477-488] and its descendants. Here we consider the following two effects: (1) lethal male-male combat and (2) time-dependent control (or schedule) of sex ratio. The former is denoted by a male mortality being an increasing function of the number of males. The optimal schedule is analytically obtained as an evolutionarily stable strategy (ESS) by using Pontrjagin's maximum principle. As a result, an ESS is a schedule where only males are produced first, then the proportion of females are gradually increased, and finally only females are produced. Total sex ratio (sex ratio averaged over the whole reproduction period) is more female-biased than the Hamilton's result if and only if the two effects work together. The bias is stronger when lethal male combat is severer or a reproduction period is longer. When male-male combat is very severe, the sex ratio can be extraordinary female-biased (less than 5%). The model assumptions and the results generally agree with experimental data on Melittobia wasps in which extraordinary female-biased sex ratio is observed. Our study might provide a new basis for the evolution of female-biased sex ratios in local mate competition.