Wild gathered food plants in the European mediterranean: A comparative analysis

The Mediterranean basin has a long and multifaceted cultural history and harbors a high biodiversity. Epidemiological studies have drawn attention to certain traditional Mediterranean diets. However, wild gathered food species, which are an important, but fast disappearing element of these diets, so far have been largely neglected in scientific studies. In this study we compare ethnobotanical data obtained from field studies conducted in Southern Italy, Southern Spain, mainland Greece, and Crete resulting in the identification of a core group of 18 culinary used wild gathered plant species. This group comprises species likePapaver rhoeas L.,Sonchus asper L.,S. oleraceus L., andSilene vulgaris L. We argue that the culinary use of wild gathered weedy greens evolved together with the neolithization process, since this offered the necessary ecological niches for them to thrive, thereby enriching and securing the diets of European agriculturalists. Especially wild gathered Asteraceae species seem to form a sort of proto-nutraceutical, which accounts for a significant input of biologically active compounds in the diet.     

Evaluating the Effect of Disturbed Ensemble Distributions on SCFG Based Statistical Sampling of RNA Secondary Structures

ABSTRACT: BACKGROUND: Over the past years, statistical and Bayesian approaches have become increasingly appreciated to address the long-standing problem of computational RNA structure prediction. Recently, a novel probabilistic method for the prediction of RNA secondary structures from a single sequence has been studied which is based on generating statistically representative and reproducible samples of the entire ensemble of feasible structures for a particular input sequence. This method samples the possible foldings from a distribution implied by a sophisticated (traditional or length- dependent) stochastic context-free grammar (SCFG) that mirrors the standard thermodynamic model applied in modern physics-based prediction algorithms. Specifically, that grammar represents an exact probabilistic counterpart to the energy model underlying the Sfold software, which employs a sampling extension of the partition function (PF) approach to produce statistically representative subsets of the Boltzmann-weighted ensemble. Although both sampling approaches have the same worst-case time and space complexities, it has been indicated that they differ in performance (both with respect to prediction accuracy and quality of generated samples), where neither of these two competing approaches generally outperforms the other. RESULTS: In this work, we will consider the SCFG based approach in order to perform an analysis on how the quality of generated sample sets and the corresponding prediction accuracy changes when different degrees of disturbances are incorporated into the needed sampling probabilities. This is motivated by the fact that if the results prove to be resistant to large errors on the distinct sampling probabilities (compared to the exact ones), then it will be an indication that these probabilities do not need to be computed exactly, but it may be sufficient and more efficient to approximate them. Thus, it might then be possible to decrease the worst-case time requirements of such an SCFG based sampling method without significant accuracy losses. If, on the other hand, the quality of sampled structures can be observed to strongly react to slight disturbances, there is little hope for improving the complexity by heuristic procedures. We hence provide a reliable test for the hypothesis that a heuristic method could be implemented to improve the time scaling of RNA secondary structure prediction in the worst-case -- without sacrificing much of the accuracy of the results. CONCLUSIONS: Our experiments indicate that absolute errors generally lead to the generation of useless sample sets, whereas relative errors seem to have only small negative impact on both the predictive accuracy and the overall quality of resulting structure samples. Based on these observations, we present some useful ideas for developing a time-reduced sampling method guaranteeing an acceptable predictive accuracy. We also discuss some inherent drawbacks that arise in the context of approximation. The key results of this paper are crucial for the design of an efficient and competitive heuristic prediction method based on the increasingly accepted and attractive statistical sampling approach. This has indeed been indicated by the construction of prototype algorithms (see [25]).     

Lipid metabolism in cancer

Lipids form a diverse group of water-insoluble molecules that include triacylglycerides, phosphoglycerides, sterols and sphingolipids. They play several important roles at cellular and organismal levels. Fatty acids are the major building blocks for the synthesis of triacylglycerides, which are mainly used for energy storage. Phosphoglycerides, together with sterols and sphingolipids, represent the major structural components of biological membranes. Lipids can also have important roles in signalling, functioning as second messengers and as hormones. There is increasing evidence that cancer cells show specific alterations in different aspects of lipid metabolism. These alterations can affect the availability of structural lipids for the synthesis of membranes, the synthesis and degradation of lipids that contribute to energy homeostasis and the abundance of lipids with signalling functions. Changes in lipid metabolism can affect numerous cellular processes, including cell growth, proliferation, differentiation and motility. This review will examine some of the alterations in lipid metabolism that have been reported in cancer, at both cellular and organismal levels, and discuss how they contribute to different aspects of tumourigenesis.     

Visual ecology of Indian carpenter bees I: Light intensities and flight activity

Bees are mostly active during the daytime, but nocturnality has been reported in some bee families. We studied temporal flight activity in three species of carpenter bees (genus Xylocopa) in relation to light intensities. X. leucothorax is diurnal, X. tenuiscapa is largely diurnal being only occasionally crepuscular, while X. tranquebarica is truly nocturnal. Occasional forays into dim light by X. tenuiscapa are likely to be due to the availability of richly rewarding Heterophragma quadriloculare (Bignoniaceae) flowers, which open at night. X. tranquebarica can fly even during the moonless parts of nights when light intensities were lower than 10⁻⁵ cd m⁻², which makes this species the only truly nocturnal bee known so far. Other known dim-light species fly during crepuscular or moonlit periods. We compare eye and body sizes with other known diurnal and dim-light bees. We conclude that while extremely large ocellar diameters, large eye size:body size ratio, large number of ommatidia and large ommatidial diameters are all adaptations to dim-light foraging, these alone do not sufficiently explain the flights of X. tranquebarica in extremely dim light. We hypothesise that additional adaptations must confer extreme nocturnality in X. tranquebarica.     

Predicting RNA secondary structures with pseudoknots by MCMC sampling

The most probable secondary structure of an RNA molecule, given the nucleotide sequence, can be computed efficiently if a stochastic context-free grammar (SCFG) is used as the prior distribution of the secondary structure. The structures of some RNA molecules contain so-called pseudoknots. Allowing all possible configurations of pseudoknots is not compatible with context-free grammar models and makes the search for an optimal secondary structure NP-complete. We suggest a probabilistic model for RNA secondary structures with pseudoknots and present a Markov-chain Monte-Carlo Method for sampling RNA structures according to their posterior distribution for a given sequence. We favor Bayesian sampling over optimization methods in this context, because it makes the uncertainty of RNA structure predictions assessable. We demonstrate the benefit of our method in examples with tmRNA and also with simulated data. McQFold, an implementation of our method, is freely available from http://www.cs.uni-frankfurt.de/~metzler/McQFold.     

Comparing and evaluating process-based ecosystem model predictions of carbon and water fluxes in major European forest biomes

Process‐based models can be classified into: (a) terrestrial biogeochemical models (TBMs), which simulate fluxes of carbon, water and nitrogen coupled within terrestrial ecosystems, and (b) dynamic global vegetation models (DGVMs), which further couple these processes interactively with changes in slow ecosystem processes depending on resource competition, establishment, growth and mortality of different vegetation types. In this study, four models – RHESSys, GOTILWA+, LPJ‐GUESS and ORCHIDEE – representing both modelling approaches were compared and evaluated against benchmarks provided by eddy‐covariance measurements of carbon and water fluxes at 15 forest sites within the EUROFLUX project. Overall, model‐measurement agreement varied greatly among sites. Both modelling approaches have somewhat different strengths, but there was no model among those tested that universally performed well on the two variables evaluated. Small biases and errors suggest that ORCHIDEE and GOTILWA+ performed better in simulating carbon fluxes while LPJ‐GUESS and RHESSys did a better job in simulating water fluxes. In general, the models can be considered as useful tools for studies of climate change impacts on carbon and water cycling in forests. However, the various sources of variation among models simulations and between models simulations and observed data described in this study place some constraints on the results and to some extent reduce their reliability. For example, at most sites in the Mediterranean region all models generally performed poorly most likely because of problems in the representation of water stress effects on both carbon uptake by photosynthesis and carbon release by heterotrophic respiration (R_h). The use of flux data as a means of assessing key processes in models of this type is an important approach to improving model performance. Our results show that the models have value but that further model development is necessary with regard to the representation of the some of the key ecosystem processes.     

Responses of aquatic algae and cyanobacteria to solar UV-B

Continuous depletion of the stratospheric ozone layer has resulted in an increase in solar ultraviolet-B (UV-B; 280–315 nm) radiation reaching the Earth's surface. The consequences for aquatic phototrophic organisms of this small change in the solar spectrum are currently uncertain. UV radiation has been shown to adversely affect a number of photochemical and photobiological processes in a wide variety of aquatic organisms, such as cyanobacteria, phytoplankton and macroalgae. However, a number of photosynthetic organisms counteract the damaging effects of UV-B by synthesizing UV protective compounds such as mycosporine-like amino acids (MAAs) and the cyanobacterial sheath pigment, scytonemin. The aim of this contribution is to discuss the responses of algae and cyanobacteria to solar UV-B radiation and the role of photoprotective compounds in mitigating UV-B damage.     

Receptor based models for spontaneous colour choices in flies and butterflies

Colour is one of several stimuli used by herbivorous insects in host choice. Insects have between 2 and 5 different types of photoreceptors to catch quanta of different wavelengths of the spectrum. Many insects have been shown to possess opponent neural interactions between the receptors that enable them to see colour. I present simple models to describe colour choices as functions of the receptor quantum catches and linear interactions of the receptor types. Models are applied to data sets obtained from own experiments and from the literature, on Pieris brassicae and P. rapae (Lepidoptera, Pieridae), Papilio aegeus (Papilionidae), Dacus oleae (Diptera, Tephritidae) and Eristalis tenax (Syrphidae). In fruit flies, detection of green fruit is based on an inhibitory interaction between a green-sensitive receptor type and a blue-sensitive receptor type. This might explain the preference many herbivorous insects have for yellow over green stimuli. Pollen feeding in hoverflies might have evolved from yellow pollen being a super-normal stimulus for herbivorous insects. In butterflies, an additional red-receptor is involved in the colour choice for an oviposition substratum and leads to them choosing green and not yellow. The models introduced in this study open new perspective for a physiological understanding of the design of visual stimuli for monitoring and trapping pest insects.     

Chromosome structure XIII

Summary The history of chromonemata was studied in Dissosteira Carolina L. It was found that each chromosome consists of 2 chromatids at all stages which themselves are again split into half-chromatids or chromonemata proper.Multiplication of threads is believed to occur at metaphase, the cycle being strictly analogous to that of plants with large chromosomes such as Trillium, Tradescantia, Hordeum and Secale, especially the two latter. Four threads per chromosome were observed during the last premeiotic telophase, during diaphase and diakinesis. During leptotene only 2 threads can be seen because the chromosome attenuates so much that half-chromatids can no longer be resolved. The dyad chromosome contains 8 threads which were observed in first telophase and interkinesis. The chromosome of the second anaphase contains four threads again, as the threads do not multiply during the second metaphase.The chromosome threads in Dissosteira Carolina L. are not so easily fixed as those of large plant chromosomes. The resulting images are more diffuse and less obvious, nevertheless the evidence obtainable appears cogent.Approved by the Director of the New York State Agricultural Experiment Station as Journal Paper 160, August 20, 1936.