N for AsN – O for StrOcture? A strand–loop–strand motif for prokaryotic O‐glycosylation

So far, it has not been possible to identify a general sequence motif for O-glycosylation in bacteria. In this issue, Charbonneau et al. (2012) demonstrate why O-glycosylation is mediated by a 13-residue strand-loop-strand motif which is part of a 19-residue imperfect repeat in the passenger domain of bacterial autotransporters. This motif provides a convenient 'glycosylation cassette' and raises intriguing questions about the structural regulation of the glycosylation pathway.     

Fadenwürmer – fade Würmer?

Nematodes – there is more to it … Nematodes play a central role – not only in a negative way as dreaded parasites of humans, animals and plants, where they may be harmful in terms of health and economy. The majority of nematodes turn out to be highly beneficial: Firstly, they are a vital part of the food web and by this indispensably involved in nutrient cycles. On the other hand, we increasingly make use of nematodes in biological control of pest organisms, in the ecotoxicological assessment of soils and sediments and as excellent model organisms in a broad range of different research fields.     

Aquakultur – quo vadis?!

Aquaculture – quo vadis? Aquaculture is more than just fish production; it is a globally active sector of the food production industry. The production methods interact in different degrees with the environment, resulting in possible negative impact. Through enhancement of the production systems as well as utilized resources, such influence can be controlled and minimized. This includes the amount of water consumption, nutrient efficiency and thus nutrient excretion from the production systems. An optimization of the culture conditions has direct benefits for animal welfare, diseases resistance, product quality and consequently supporting the productivity of the aquaculture enterprises. Further support and networking of the stakeholders involved in education, research and private companies within the respective fields is required to reach the overall goal of an ecologically and economically sustainable aquaculture.     

Adipositas – eine Bürde der Evolution?

Obesity – a consequence of evolution? The high obesity rates are the result of a dramatic mismatch between current environment and a human body evolved in the environment of our evolutionary adaptedness. Various evolutionary hypotheses try to explain this relationship. Natural and sexual selection shaped our gene pool towards an optimal adaptation to these environments and life circumstances. Our recent obesogenic environment differs dramatically from that in which we evolved.     

Biodiversitätsforschung – wohin geht die Reise?

Biodiversity and biodiversity politics Extrapolations for a range of indicators suggest that based on current trends, pressures on biodiversity will continue to increase (Global Biodiversity Outlook 4, 2014). Since services of nature, like fertile soil, clear water and clean air are achieved by consortia of organisms rather than by individual species, they are already endangered. This holds, in spite of the fact, that only 10% of the earth's organisms are known to science and that therefore the loss caused by global change cannot be reliably quantified. Today, science develops new methods for recording consortia of coexisting organisms in a habitat. With the Convention on Biological Diversity, biodiversity has become a matter of politics which is welcome with respect to species and habitat conservation, but the concern of biopiracy creates bureaucratic hurdles hindering research. The most recent achievement is IPBES (Intergovernmental Platform on Biodiversity and Ecosystem Services, Bonn), which strives to bring more science into biodiversity politics.     

Gliotoxin – bane or boon?

Gliotoxin (GT) is the most important epidithiodioxopiperazine (ETP)‐type fungal toxin. GT was originally isolated from Trichoderma species as an antibiotic substance involved in biological control of plant pathogenic fungi. A few isolates of GT‐producing Trichoderma virens are commercially marketed for biological control and widely used in agriculture. Furthermore, GT is long known as an immunosuppressive agent and also reported to have anti‐tumour properties. However, recent publications suggest that GT is a virulence determinant of the human pathogen Aspergillus fumigatus. This compound is thus important on several counts – it has medicinal properties, is a pathogenicity determinant, is a potential diagnostic marker and is important in biological crop protection. The present article addresses this paradox and the ecological role of GT. We discuss the function of GT as defence molecule, the role in aspergillosis and suggest solutions for safe application of Trichoderma‐based biofungicides.     

Dinoflagellaten – ein Dauerexperiment der Evolution?

Dinoflagellates play important roles in marine food webs, both as primary producers and as heterotrophic consumers. They produce spectacular phenomena like marine bioluminescence and red tides, and are major components of coral reefs. Members of the group can also synthesize some of the most toxic biogenic compounds currently known. Dinoflagellate's nuclei are extremely large and biochemically unique, while mitochondrial genomes are very small. The plastid diversity of dinoflagellates is also unique: only about half of the species in the group are photosynthetic, but the origin of their plastids is often different. As a consequence dinoflagellate plastids have very diverse physiological and biochemical characteristics. Some of the most complex morphological constructs known in unicellular organisms are found in this group. These include ?harpoons“, used to capture prey, and ?eyes“, that contain substructures reminiscent of lenses, corneas and retinas.     

Brachiopod caeca – a respiratory role?

Recently the author presented data which supported the suggestion (Owen & Williams 1969) that the brachiopod caeca can inhibit boring organisms and store excess nutrients (Curry 1983). In the light of this work it is appropriate to describe and discuss an additional function which has been proposed for the caeca, especially as the data appear in a zoological journal which may not otherwise come to the attention of brachiopod palaeontologists.     

Cambrian lobopodians–ancestors of extant onychophorans?

This paper is a review of published information on fossil lobopodians, with addition of observations and ideas based on new material. It is also an analysis of the phytogeny of the group, and presents a new classification. A character shared by three or four families, yet not seen before, is a pair of enlarged sclerites covering the head. This forms an argument for re-orienting Hallucigenia once again. This genus no longer being enigmatic, a corner-stone in Stephen Jay Gould's evidence for extinct phyla is therefore gone. It is suggested that the lobopodians, phylum Lobopodia, are arranged in two classes, the extinct Xenusia for marine forms, and the Onychophora for terrestrial forms. The marine lobopodians are morphologically much more diverse than the extant onychophorans, a condition expressed in the classification. New taxa are: Hallucigenia fortis sp. nov., the families Luolishaniidae, Cardiodictyidae and Onychodictyidae, and the new orders Archonychophora, Scleronychophora and Paronychophora.     

Behavioural synchronization of large‐scale animal movements – disperse alone,but migrate together?

Dispersal and migration are superficially similar large‐scale movements, but which appear to differ in terms of inter‐individual behavioural synchronization. Seasonal migration is a striking example of coordinated behaviour, enabling animal populations to track spatio‐temporal variation in ecological conditions. By contrast, for dispersal, while social context may influence an individual's emigration and settlement decisions, transience is believed to be mostly a solitary behaviour. Here, we review differences in drivers that may explain why migration appears to be more synchronized than dispersal. We derive the prediction that the contrast in the importance of behavioural synchronization between dispersal and migration is linked to differences in the selection pressures that drive their respective evolution. Although documented examples of collective dispersal are rare, this behaviour may be more common than currently believed, with important consequences for eco‐evolutionary dynamics. Crucially, to date, there is little available theory for predicting when we should expect collective dispersal to evolve, and we also lack empirical data to test predictions across species. By reviewing the state of the art in research on migration and collective movements, we identify how we can harness these advances, both in terms of theory and data collection, to broaden our understanding of synchronized dispersal and its importance in the context of global change.     

How does winter pruning affect peach tree–Myzus persicae interactions?

Winter tree pruning is a cultural practice known to modify vegetative growth, which is likely to affect the development of pests. However, it has been poorly addressed as a cultural control method for diminishing the population levels of the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae), in peach [ Prunus persica (L.) Batsch (Rosaceae)] orchards. In this study, we conducted a 2-year, on-station experiment to evaluate how winter pruning affects peach– M. persicae interactions, by examining tree vegetative growth, aphid population dynamics, and crop yield and fruit quality. We collected data under an insect-proof shelter on adult peach trees submitted to various levels of pruning and artificially infested with aphids. Our results showed that pruning enhanced shoot growth due to the proportion of growing shoots, which increased exponentially (10–60%), whereas the growth rate of growing shoots was not affected. The degree of infestation of peach trees increased with increasing pruning intensity. This effect was mainly due to the increase of the proportion of growing shoots, on which aphids developed better than on rosettes. In turn, the higher the aphid infestation, the higher the aphid-induced shoot-tip damage, leaf curling, and leaf fall that disturbed the growth of growing shoots. However, aphids did not considerably reduce fruit quality at harvest. They did not affect fresh fruit weight, and the refractometric index (indicator of sugar content) was reduced by only 3–4%. The relevance of winter pruning as a cultural method for pest control in orchards conducted under integrated fruit production guidelines is discussed.     

FtsK – a bacterial cell division checkpoint?

FtsK is a multifunctional, multidomain protein that acts to co-ordinate chromosome unlinking, segregation and cell division. In this issue of Molecular Microbiology, the report by Dubarry et al. reveals new insight into the surprisingly complex relationship between the different activities of FtsK. The new study makes extensive use of fusion proteins to highlight the role of the FtsK 'linker' domain in helping to co-ordinate these processes. This, taken together with previous studies, suggests that FtsK is intimately involved in septum constriction, physically contacting several other divisome proteins. Further, it is attractive to speculate that FtsK can regulate the late stages of septation to act as a checkpoint to ensure DNA is fully cleared from the septum before it is allowed to close, as well as being the driving force to unlink the chromosomes and segregate the DNA away from the septum.     

Can stochastic geographical evolution re‐create macroecological richness–environment correlations?

Aim Richness gradients are frequently correlated with environmental characteristics at broad geographic scales. In particular, richness is often associated with energy and climate, while environmental heterogeneity is rarely its best correlate. These correlations have been interpreted as evidence in favour of environmental determinants of diversity gradients, particularly energy and climate. This interpretation assumes that the expected‐by‐random correlation between richness and environment is zero, and that this is equally true for all environmental characteristics. However, these expectations might be unrealistic. We investigated to what degree basic evolutionary/biogeographical processes occurring independently of environment could lead to richness gradients that correlate with environmental characteristics by chance alone. Location Africa, Australia, Eurasia and the New World. Methods We produced artificial richness gradients based on a stochastic simulation model of geographic diversification of clades. In these simulations, species speciate, go extinct and expand or shift their distributions independently of any environmental characteristic. One thousand two hundred repetitions of this model were run, and the resulting stochastic richness gradients were regressed against real‐world environmental variables. Stochastic species–environment relationships were then compared among continents and among three environmental characteristics: energy, environmental heterogeneity and climate seasonality. Results Simulations suggested that a significant degree of correlation between richness gradients and environment is expected even when clades diversify and species distribute stochastically. These correlations vary considerably in strength; but in the best cases, environment can spuriously account for almost 80% of variation in stochastic richness. Additionally, expected‐by‐chance relationships were different among continents and environmental characteristics, producing stronger spurious relationships with energy and climate than with heterogeneity. Main conclusions We conclude that some features of empirical species–environment relationships can be reproduced just by chance when taking into account evolutionary/biogeographical processes underlying the construction of species richness gradients. Future tests of environmental effects on richness should consider structure in richness–environment correlations that can be produced by simple evolutionary null models. Research should move away from the naive non‐biological null hypotheses that are implicit in traditional statistical tests.     

Death by transposition – the enemy within?

Here we present and develop the hypothesis that the derepression of endogenous retrotransposable elements (RTEs) – “genomic parasites” – is an important and hitherto under‐unexplored molecular aging process that can potentially occur in most tissues. We further envision that the activation and continued presence of retrotransposition contribute to age‐associated tissue degeneration and pathology. Chromatin is a complex and dynamic structure that needs to be maintained in a functional state throughout our lifetime. Studies of diverse species have revealed that chromatin undergoes extensive rearrangements during aging. Cellular senescence, an important component of mammalian aging, has recently been associated with decreased heterochromatinization of normally silenced regions of the genome. These changes lead to the expression of RTEs, culminating in their transposition. RTEs are common in all kingdoms of life, and comprise close to 50% of mammalian genomes. They are tightly controlled, as their activity is highly destabilizing and mutagenic to their resident genomes.