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Pollination syndromes and their predictive power regarding actual plant-animal interactions have been controversially discussed in the past. We investigate pollination syndromes in Balsaminaceae, utilizing quantitative respectively categorical data sets of flower morphometry, signal and reward traits for 86 species to test for the effect of different types of data on the test patterns retrieved. Cluster Analyses of the floral traits are used in combination with independent pollinator observations. Based on quantitative data we retrieve seven clusters, six of them corresponding to plausible pollination syndromes and one additional, well-supported cluster comprising highly divergent floral architectures. This latter cluster represents a non-syndrome of flowers not segregated by the specific data set here used. Conversely, using categorical data we obtained only a rudimentary resolution of pollination syndromes, in line with several earlier studies. The results underscore that the use of functional, exactly quanitified trait data has the power to retrieve pollination syndromes circumscribed by the specific data used. Data quality can, however, not be replaced by sheer data volume. With this caveat, it is possible to identify pollination syndromes from large datasets and to reliably extrapolate them for taxa for which direct observations are unavailable.
Natural products and their semisynthetic derivatives are an important source of drugs for the pharmaceutical industry. Bacteria are prolific producers of natural products and encode a vast diversity of natural product biosynthetic gene clusters. However, much of this diversity is inaccessible to natural product discovery. Here, we use a combination of phylogenomic analysis of the microviridin biosynthetic pathway and chemo-enzymatic synthesis of bioinformatically predicted microviridins to yield new protease inhibitors. Phylogenomic analysis demonstrated that microviridin biosynthetic gene clusters occur across the bacterial domain and encode three distinct subtypes of precursor peptides. Our analysis shed light on the evolution of microviridin biosynthesis and enabled prioritization of their chemo-enzymatic production. Targeted one-pot synthesis of four microviridins encoded by the cyanobacterium Cyanothece sp. PCC 7822 identified a set of novel and potent serine protease inhibitors, the most active of which had an IC50 value of 21.5 nM. This study advances the genome mining techniques available for natural product discovery and obviates the need to culture bacteria.
Vitamin E inhibits the propagation of lipid peroxidation and helps protecting photosystem II from photoinhibition, but little is known about its possible role in plant response to Pi availability. Here, we aimed at examining the effect of vitamin E deficiency in Arabidopsis thaliana vte mutants on phytohormone contents and the expression of transcription factors in plants exposed to contrasting Pi availability. Plants were subjected to two doses of Pi, either unprimed (controls) or previously exposed to low Pi (primed). In the wild type, alpha-tocopherol contents increased significantly in response to repeated periods of low Pi, which was paralleled by increased growth, indicative of a priming effect. This growth-stimulating effect was, however, abolished in vte mutants. Hormonal profiling revealed significant effects of Pi availability, priming and genotype on the contents of jasmonates and salicylates; remarkably, vte mutants showed enhanced accumulation of both hormones under low Pi. Furthermore, expression profiling of 1,880 transcription factors by qRT-PCR revealed a pronounced effect of priming on the transcript levels of 45 transcription factors mainly associated with growth and stress in wild-type plants in response to low Pi availability; while distinct differences in the transcriptional response were detected in vte mutants. We conclude that alpha-tocopherol plays a major role in the response of plants to Pi availability not only by protecting plants from photo-oxidative stress, but also by exerting a control over growth-and defense-related transcriptional reprogramming and hormonal modulation.
Sediment resuspension represents a key process in all natural aquatic systems, owing to its role in nutrient cycling and transport of potential contaminants. Although suspended solids are generally accepted as an important quality parameter, current monitoring programs cover quantitative aspects only. Established methodologies do not provide information on origin, fate, and risks associated with uncontrolled inputs of solids in waters. Here we discuss the analytical approaches to assess the occurrence and ecological relevance of resuspended particulate matter in freshwaters, with a focus on the dynamics of associated contaminants and microorganisms. Triggered by the identification of specific physical-chemical traits and community structure of particle-associated microorganisms, recent findings suggest that a quantitative determination of microorganisms can be reasonably used to trace the origin of particulate matter by means of nucleic acid-based assays in different aquatic systems.
Kettle holes are small inland waters formed from glacially-created depressions often situated in agricultural landscapes. Due to their high perimeter-to-area ratio facilitating a high aquatic-terrestrial coupling, kettle holes can accumulate high concentrations of organic carbon and nutrients, fueling microbial activities and turnover rates. Thus, they represent hotspots of carbon turnover in the landscape, but their bacterial activities and controlling factors have not been well investigated. Therefore, we aimed to assess the relative importance of various environmental factors on bacterial and biogeochemical processes in the water column of kettle holes and to disentangle their variations. In the water body of ten kettle holes in north-eastern Germany, we measured several physico-chemical and biological parameters such as carbon quantity and quality, as well as bacterial protein production (BP) and community respiration (CR) in spring, early summer and autumn 2014. Particulate organic matter served as an indicator of autochthonous production and represented an important parameter to explain variations in BP and CR. This notion is supported by qualitative absorbance indices of dissolved molecules in water samples and C: N ratios of the sediments, which demonstrate high fractions of autochthonous organic matter (OM) in the studied kettle holes. In contrast, dissolved chemical parameters were less important for bacterial activities although they revealed strong differences throughout the growing season. Pelagic bacterial activities and dynamics might thus be regulated by autochthonous OM in kettle holes implying a control of important biogeochemical processes by internal primary production rather than facilitated exchange with the terrestrial surrounding due to a high perimeter-to-area ratio.
The ecological benefits of polyploidy are intensely debated. Some authors argue that plants with duplicated chromosome sets (polyploids) are more stress- resistant and superior colonizers and may thus outnumber their low ploidy conspecifics in more extreme habitats. Brachypodium distachyon (sensu lato), for example, a common annual grass in Israel and the entire Mediterranean basin, comprises three cytotypes of differing chromosome numbers that were recently proposed as distinct species. It was suggested that increased aridity increases the occurrence of its polyploid cytotype. Here, we tested at two spatial scales whether polyploid plants of B. distachyon s. l. are more frequently found in drier habitats in Israel. We collected a total of 430 specimens (i) along a largescale climatic gradient with 15 thoroughly selected sites (spanning 114- 954 mm annual rainfall), and (ii) from corresponding Northern (more mesic) and Southern (more arid) hill slopes to assess the micro- climatic difference between contrasting exposures. Cytotypes were then determined via flow cytometry. Polyploid plants comprised 90% of all specimens and their proportion ranged between 0% and 100% per site. However, this proportion was not correlated with aridity along the large- scale gradient, nor were polyploids more frequently found on Southern exposures. Our results show for both spatial scales that increasing aridity is not the principal driver for the distribution of polyploids in B. distachyon s. l. in Israel. Notably, though, diploid plants were restricted essentially to four intermediate sites, while polyploids dominated the most arid and the most mesic sites. This, to some degree, clustered pattern suggests that the distribution of cytotypes is not entirely random and calls for future studies to assess further potential drivers.
Inhibition of MAP kinase pathways by selective BRAF inhibitors, such as vemurafenib and dabrafenib, have evolved as key therapies of BRAF-mutated melanoma. However, tumor relapse and therapy resistance have remained as major problems, which may be addressed by combination with other pathway inhibitors. Here we identified the potassium channel inhibitor TRAM-34 as highly effective in combination with vemurafenib. Thus apoptosis was significantly enhanced and cell viability was decreased. The combination vemurafenib/TRAM-34 was also effective in vemurafenib-resistant cells, suggesting that acquired resistance may be overcome. Vemurafenib decreased ERK phosphorylation, suppressed antiapoptotic Mcl-1 and enhanced proapoptotic Puma and Bim. The combination resulted in enhancement of proapoptotic pathways as caspase-3 and loss of mitochondrial membrane potential. Indicating a special mechanism of vemurafenib-induced apoptosis, we found strong enhancement of intracellular ROS levels already at 1 h of treatment. The critical role of ROS was demonstrated by the antioxidant vitamin E (alpha-tocopherol), which decreased intracellular ROS as well as apoptosis. Also caspase activation and loss of mitochondrial membrane potential were suppressed, proving ROS as an upstream effect. Thus ROS represents an initial and independent apoptosis pathway in melanoma cells that is of particular importance for vemurafenib and its combination with TRAM-34.
Plio-Pleistocene phylogeography of the Southeast Asian Blue Panchax killifish, Aplocheilus panchax
(2017)
MADS-domain transcription factors are well known for their roles in plant development and regulate sets of downstream genes that have been uncovered by high-throughput analyses. A considerable number of these targets are predicted to function in hormone responses or responses to environmental stimuli, suggesting that there is a close link between developmental and environmental regulators of plant growth and development. Here, we show that the Arabidopsis MADS-domain factor FRUITFULL (FUL) executes several functions in addition to its noted role in fruit development. Among the direct targets of FUL, we identified SMALL AUXIN UPREGULATED RNA 10 (SAUR10), a growth regulator that is highly induced by a combination of auxin and brassinosteroids and in response to reduced R:FR light. Interestingly, we discovered that SAUR10 is repressed by FUL in stems and inflorescence branches. SAUR10 is specifically expressed at the abaxial side of these branches and this localized activity is influenced by hormones, light conditions and by FUL, which has an effect on branch angle. Furthermore, we identified a number of other genes involved in hormone pathways and light signalling as direct targets of FUL in the stem, demonstrating a connection between developmentally and environmentally regulated growth programs.
Twenty two species of ectoparasites (Family Nycteribiidae: Nycteribia (Listropoda) schmidlii schmidlii, Nycteribia (Nycteribia) latreillii, Nycteribia (Nycteribia) pedicularia, Penicillidia (Penicillidia) dufourii, and Phthiridium biarticulatum; Family Streblidae: Brachytarsina (Brachytarsina) flavipennis and Raymondia huberi; Order Siphonaptera: Rhinolophopsylla unipectinata arabs, Nycteridopsylla longiceps, Araeopsylla gestroi, Ischnopsyllus intermedius, and Ischnopsyllus octactenus; Order Heteroptera: Cimex pipistrelli, Cimex lectularius, and Cacodmus vicinus; Class Arachnida: Order Mesostigmata: Spinturnix myoti and Eyndhovenia euryalis; Order Ixodida: Family Argasidae: Argas transgariepinus and Argas vespertilionis; Family Ixodidae: Hyalomma dromedarii, Ixodes ricinus, and Ixodes vespertilionis) were recovered from 19 bat species in Algeria. New host records for bats are recorded for the first time: N. schmidlii from Rh. clivosus and R. cystops; N. latreillii from Rh. blasii and P. gaisleri; R. huberi from Rh. clivosus; C. pipistrelli from E. isabellinus and H. savii; C. vicinus from E. isabellinus; S. myoti from P. gaisleri; E. euryalis from P. gaisleri and Rh. blasii; A. vespertilionis from P. gaisleri; I. ricinus from T. teniotis and Rh. hipposideros and H. dromedarii from P. kuhlii. Raymondia huberi is recorded for the first time from Algeria.
Predator-prey oscillations are expected to show a 1/4-phase lag between predator and prey. However, observed dynamics of natural or experimental predator-prey systems are often more complex. A striking but hardly studied example are sudden interruptions of classic 1/4-lag cycles with periods of antiphase oscillations, or periods without any regular predator-prey oscillations. These interruptions occur for a limited time before the system reverts to regular 1/4-lag oscillations, thus yielding intermittent cycles. Reasons for this behaviour are often difficult to reveal in experimental systems. Here we test the hypothesis that such complex dynamical behaviour may result from minor trait variation and trait adaptation in both the prey and predator, causing recurrent small changes in attack rates that may be hard to capture by empirical measurements. Using a model structure where the degree of trait variation in the predator can be explicitly controlled, we show that a very limited amount of adaptation resulting in 10-15% temporal variation in attack rates is already sufficient to generate these intermittent dynamics. Such minor variation may be present in experimental predator-prey systems, and may explain disruptions in regular 1/4-lag oscillations.
Background: We investigated height of Norwegian conscripts in view of the hypothesis of a "community effect on height" using autocorrelation analysis of district heights within a time-span of 20 years at the end of the 19th century and correlations between neighboring districts at this time. Material and methods: After digitalizing available body height data of Norwegian draftees in 1877-1878, 1880 (averaged as 1878), and 1895-1897 (averaged as 1896) we calculated the magnitude of autocorrelation of body height within the same municipality at different time points. Furthermore, we generated three different neighborhood networks, (1) based on Euclidean distances, (2) a minimum spanning tree build on those distances, (3) a network founded on real world road connections. The networks were used to determine the correlation between body height of neighboring districts depending on the number of edges required to connect two municipalities. Results: The autocorrelation value for body heights was around r = 0.5 (for all p < 0.001) in the years 1878 and 1896. The correlation between neighboring districts varied in the Euclidean distance based network between 0.47 and 0.27 approximately for both years in a sorted order, descending from nearest (0-50 km) to farthest (150-200 km, for all p < 0.001). First order neighbors in the minimum spanning tree network correlation was 0.36 in 1878 and 0.42 in 1896 (for all p < 0.001). The values of neighbor correlation in the road connection based network ranged in 1878 from 0.42 (first order neighbors) to 0.17 (forth order neighbors, for all p < 0.01) and in 1896 from 0.46 (first order neighbors) to 0.12 (forth order neighbors, for all p < 0.05). Conclusion: This initial study of Norwegian conscript height data from the 19th century showed significant medium sized effects for the within district autocorrelation between 1878 and 1896 as well as medium neighborhood correlation, slightly lower in comparison to a recent study regarding Swiss conscripts. Digitalizing more data from other years in this and later time spans as well as using older road and ship connections instead of the actual road data might stabilize and improve those findings.
Spatial environmental heterogeneity is considered a fundamental factor for the maintenance of plant species richness. However, it still remains unclear whether heterogeneity may also facilitate coexistence at fine grain sizes or whether other processes, like mass effects and source sink dynamics due to dispersal, control species composition and diversity at these scales. In this study, we used two complimentary analyses to identify the role of heterogeneity within 15 m x 15 m plots for the coexistence of species-rich annual communities in a semi-arid environment along a steep precipitation gradient. Specifically, we: (a) analyzed the effect of environmental heterogeneity on species, functional and phylogenetic diversity within microsites (alpha diversity, 0.06 m(2) and 1 m(2)), across microsites (beta diversity), and diversity at the entire plot (gamma diversity); (b) further we used two null models to detect non-random trait and phylogenetic patterns in order to infer assembly processes, i.e. whether co-occurring species tend to share similar traits (trait convergence) or dissimilar traits (trait divergence). In general, our results showed that heterogeneity had a positive effect on community diversity. Specifically, for alpha diversity, the effect was significant for functional diversity, and not significant for either species or phylogenetic diversities. For beta diversity, all three measures of community diversity (species, functional, and phylogenetic) increased significantly, as they also did for gamma diversity, where functional measures were again stronger than for species or phylogenetic measures. In addition, the null model approach consistently detected trait convergence, indicating that species with similar traits tended to co-occur and had high abundances in a given microsite. While null model analysis across the phylogeny partly supported these trait findings, showing phylogenetic underdispersion at the 1m(2) grain size, surprisingly when species abundances in microsites were analyzed they were more evenly distributed across the phylogenetic tress than expected (phylogenetic overdispersion). In conclusion, our results provide compelling support that environmental heterogeneity at a relatively fine scale is an important factor for species co-existence as it positively affects diversity as well as influences species assembly. Our study underlines the need for trait-based approaches conducted at fine grain sizes in order to better understand species coexistence and community assembly. (C) 2017 Elsevier GmbH. All rights reserved.
Intraspecific trait variability plays an important role in species adaptation to climate change. However, it still remains unclear how plants in semi-arid environments respond to increasing aridity. We investigated the intraspecific trait variability of two common Mediterranean annuals (Geropogon hybridus and Crupina crupinastrum) with similar habitat preferences. They were studied along a steep precipitation gradient in Israel similar to the maximum predicted precipitation changes in the eastern Mediterranean basin (i.e. -30% until 2100). We expected a shift from competitive ability to stress tolerance with decreasing precipitation and tested this expectation by measuring key functional traits (canopy and seed release height, specific leaf area, N-and P-leaf content, seed mass). Further, we evaluated generative bet-hedging strategies by different seed traits. Both species showed different responses along the precipitation gradient. C. crupinastrum exhibited only decreased plant height toward saridity, while G. hybridus showed strong trends of generative adaptation to aridity. Different seed trait indices suggest increased bet-hedging of G. hybridus in arid environments. However, no clear trends along the precipitation gradient were observed in leaf traits (specific leaf area and leaf N-/P-content) in both species. Moreover, variance decomposition revealed that most of the observed trait variation (>> 50%) is found within populations. The findings of our study suggest that responses to increased aridity are highly species-specific and local environmental factors may have a stronger effect on intraspecific trait variation than shifts in annual precipitation. We therefore argue that trait-based analyses should focus on precipitation gradients that are comparable to predicted precipitation changes and compare precipitation effects to effects of local environmental factors. (C) 2017 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.