Isoflavonoids in non-leguminous taxa: a rarity or a rule?

Isoflavonoids are characteristic metabolites in legumes and an overwhelming number of reports concerning them come from the Leguminosae. Nevertheless, the spectrum of isoflavonoid producing taxa includes the representatives of four classes of multicellular plants, namely the Bryopsida, the Pinopsida, the Magnoliopsida and the Liliopsida. At least 59 non-leguminous families have been reported to produce isoflavones sensu lato; coumestans have been reported in 3 families, coumaronochromones in 3, pterocarpans in 9 and rotenoids in 8 families. Prenylated isoflavones have been found in 15 non-leguminous families and isoflavone dimers, heterodimers or oligomers in three families. More than two hundred different isoflavonoid aglycones have been reported in non-legumes altogether. The number of individual structures is even greater if the variety of glycosides are considered. Enzymology and genetics of isoflavonoid biosynthesis have been studied almost exclusively in legumes, with the exception of a few model plants (i.e. Beta vulgaris, Arabidopsis thaliana, Nicotiana tabacum and Zea mays). The key step at the very beginning of the isoflavonoid metabolic pathway is the oxidation of flavanone connected with the migration of aryl moiety from C2 to C3 mediated by a CYP450 enzyme isoflavone synthase (IFS), which has been identified and cloned in multiple legumes and in sugar beet (Beta vulgaris, Chenopodiaceae). No information is available about the enzyme(s) responsible for the biosynthesis of isoflavonoid core in other taxa. Experimental data demonstrates the capability of numerous enzymes of non-legume origin to metabolize isoflavones as alternative substrates to other phenolics.     

Understanding global patterns in amphibian geographic range size: does Rapoport rule?

Aim Species geographic ranges are the ‘fundamental units’ of macroecology. Range size is a major correlate of extinction risk in many groups, and is also critical in studies of biotic responses to climate change. Despite this, there is a lack of studies exploring the role of environmental, historical and anthropogenic processes in determining large‐scale patterns in range size. We perform the first global analysis of putative drivers of range size variation in any group, choosing amphibians as our study taxon. Our aims are to disentangle the many hypothesized causes of range size variation and evaluate support for ‘Rapoport's rule’, the observation that range size correlates with latitude. Location Global. Methods We develop a global map of gridded median range size using the International Union for Conservation of Nature (IUCN) distribution maps. From this we perform spatial and non‐spatial regressions to explore relationships between range size and nine hypothesized variables in six biogeographic realms. We use information‐theoretic model selection to compare multiple competing variables, simultaneously evaluating the relative support for each one. Results Current climate – environmental water and energy, and temperature seasonality – is consistently highly ranked in spatial and non‐spatial analyses. Human impacts and other environmental measures (topographic and landscape complexity, effective area, climate extremes) show mixed support, and glacial history is consistently unimportant. Our findings add further evidence to the view that Rapoport's rule is a regional, not global, phenomenon. Main conclusions The primary importance of temperature seasonality may explain why Rapoport's rule is largely restricted to northern latitudes, as this is where seasonality is most pronounced. More generally, the dominance of contemporary climate in our analyses (even when accounting for space) has stark implications for the future status of amphibians. Changes in climate will almost certainly interact with the anthropogenic processes already threatening a third of amphibians globally, with the effects being most keenly felt by species with a restricted range.     

Which provenance and where? Seed sourcing strategies for revegetation in a changing environment

Revegetation is one practical application of science that should ideally aim to combine ecology with evolution to maximise biodiversity and ecosystem outcomes. The strict use of locally sourced seed in revegetation programs is widespread and is based on the expectation that populations are locally adapted. This practice does not fully integrate two global drivers of ecosystem change and biodiversity loss: habitat fragmentation and climate change. Here, we suggest amendments to existing strategies combined with a review of alternative seed-sourcing strategies that propose to mitigate against these drivers. We present a provenancing selection guide based on confidence surrounding climate change distribution modelling and data on population genetic and/or environmental differences between populations. Revegetation practices will benefit from greater integration of current scientific developments and establishment of more long-term experiments is key to improving the long-term success. The rapid growth in carbon and biodiversity markets creates a favourable economic climate to achieve these outcomes.     

Phenols in reproductive and somatic structures of lichens: a case of optimal defence?

Optimal defence theory (ODT) attempts to explain variation in plant secondary compounds between different species, different growth conditions and different parts of individual plants. The theory is widely applied to vascular plants and more recently also to seaweeds. Surprisingly, ODT has gained little attention as potential explanation on the distribution of lichen secondary metabolites. In the present study, we analysed intrathalline variation in total phenol content and phenol spectra between reproductive and somatic structures of three foliose lichens, Xanthoria parietina , Vulpicida pinastri and Hypogymnia physodes . The results showed that the concentration of phenolic compounds is higher in sorediate than in non-sorediate lobe ends of V. pinastri and H. physodes as well as in apothecia of X. parietina compared to other parts of the thallus. These results were in accordance with ODT predicting higher allocation of phenols in structures that are most important for the fitness of an individual genet or ramet. This pattern was parallel in all species regardless whether the compounds originate from either acetate-mevalonate or shikimic acid pathways. Moreover, both sexual ( X. parietina apothecia) and asexual (soralia of V. pinastri and H. physodes ) reproductive structures were higher in phenols compared to somatic tissue.     

When is it optimal to exhaust a resource in a finite time?

Exhaustion of a natural resource stock may be a rational choice for an individual and/or a community, even if a sustainable use for the resource is feasible and the resource users are farsighted and well informed on the ecosystem. We identify conditions under which it is optimal not to sustain resource use. These conditions concern the discounting of future benefits, instability of a social system or ecosystem, nonconvexity of natural growth function, socio-psychological value of employment, and strategic interaction among resource users. The identification of these conditions can help design policies to prevent unsustainable patterns of resource use.      

Assessment of unloaded and loaded squat jump performance with a force platform: Which jump starting threshold provides more reliable outcomes?

This study aimed to explore the influence of different onset thresholds on the between-session reliability and magnitude of squat jump (SJ) performance. Twenty men were tested on two sessions separated by 48 h against external loads of 0.5, 30 and 60 kg. The initiation of the jump was defined as the first instant in which the vertical ground reaction force exceeded system weight by 10 N (10 N), 50 N (50 N), 1% of system weight (1%SW), 10% of system weight (10%SW) and five standard deviation of system weight minus 30 ms (5SDSW). The following variables were calculated from the force-time signal collected on a force platform: mean, peak and time to peak values of force, power and velocity, average rate of force development, peak rate of force development, rate of force development index, impulse, jump height, and push-off time. The 50 N, 10%SW and 5SDSW thresholds generally revealed a higher reliability than the 10 N and 1%SW thresholds (97 and 21 out of 252 comparisons for the coefficient of variation and intraclass correlation coefficient, respectively). The magnitude of most of the variables calculated using the 50 N and 10%SW thresholds significantly differed with respect to the 10 N, 1%SW and 5SDSW thresholds (P < 0.05). These results suggest that both the reliability and magnitude of SJ performance variables are influenced by the jump starting threshold. The 50 N, 10%SW and 5SDSW thresholds maximise the reliability of SJ performance variables, while the 5SDSW should be recommended since it considers more force signal than the 50 N and 10%SW thresholds.     

Do protein molecules unfold in a simple shear flow?

Protein molecules typically unfold (denature) when subjected to extremes of heat, cold, pH, solvent composition, or mechanical stress. One might expect that shearing forces induced by a nonuniform fluid flow would also destabilize proteins, as when a protein solution flows rapidly through a narrow channel. However, although the protein literature contains many references to shear denaturation, we find little quantitative evidence for the phenomenon. We have investigated whether a high shear can destabilize a small globular protein to any measurable extent. We study a protein (horse cytochrome c, 104 amino acids) whose fluorescence increases sharply upon unfolding. By forcing the sample through a silica capillary (inner diameter 150-180 microm) at speeds approaching 10 m/s, we subject the protein to shear rates dv(z)/dr as large as approximately 2 x 10(5) s(-1) while illuminating it with an ultraviolet laser. We can readily detect fluorescence changes of <1%, corresponding to shifts of < approximately 0.01 kJ/mol in the stability of the folded state. We find no evidence that even our highest shear rates significantly destabilize the folded protein. A simple model suggests that extraordinary shear rates, approximately 10(7) s(-1), would be required to denature typical small, globular proteins in water.     

Which seed origin provides better tolerance to flooding and drought when restoring to face climate change?

Our goal was to establish the tolerance to flooding and drought of seedlings from a hydric gradient of different seed sources to provide recommendations for forest restoration in the face of climate change. We used Drimys winteri var. chilensis, a tree species that grows from extreme arid zones to wetlands along Chile, as the study subject. We expected that seedlings of xeric origin would perform better in drought conditions than populations from moist environments, and vice versa for flooding tolerance. We collected D. winteri seeds from xeric, mesic and wet environments. Seedlings at two development stages were submitted to an extreme flooding and drought treatment during 2 or 4 months in a common garden. After the flooding and drought assays finished, the number of surviving and damaged seedlings, lenticels and adventitious root presence, height, new leaves and specific leaf area, shoot/root ratio, water potential and/or chlorophyll fluorescence (Fv/Fm), were recorded. We found that flooding and drought affected almost all the parameters studied negatively. The xeric population seedlings, at both development stages studied, were the most tolerant to the drought and, unexpectedly, also to the flooding treatment. We recommend restoring with seedlings of xeric origin especially in arid areas where sudden flooding is frequent, as occurs in the Andes Mountains. In the face of climate change, we recommend carrying out common garden and field studies before advising which population origin should be used for restoration, since they do not always respond in accordance with expected patterns of local adaptation.     

LOX-1, a new marker of risk and prognosis in coronary artery disease?

The development of atherosclerosis is caused by the accumulation of lipid, inflammatory cytokine production, and the large amount of inflammatory cells in the arterial wall. It is now established that the presence of oxidized low-density lipoproteins (ox-LDL) has an important role in the pathogenesis of the disease. There are many scavenger receptors for ox-LDL, among which LOX-1 seems to be important for the induction of endothelial dysfunction and the other subsequent events that lead to the formation of atheromatous plaque. Our findings indicate the presence of a regulatory role induced by the presence of ox-LDL on LOX-1 through the amplification of IL-6 synthesis. This mechanism contributes to the upregulation of the ORL-1 gene expression in presence of risk factors. Many authors have shown the possibility to use LOX-1 as a good marker for the diagnosis and prognosis of coronary artery disease because it is easy to measure and more sensitive than other markers commonly used in the routine of laboratory medicine.     

Orientation and Navigation in Elasmobranchs: Which Way Forward?

Elasmobranchs possess a multiplicity of mechanisms controlling posture and short distance orientation. Visual–vestibular contributions to posture and locomotion are well documented. So too, are the contributions of vision, olfaction and the octavolateralis senses to short distance orientation, particularly orientation to specific environmental stimuli such as those generated by prey. Less well understood are the mechanisms guiding orientation over longer distances. Anecdotal and systematic observations of behaviour show tidal, daily, repeat long distance, and even seasonal movement patterns. True navigation has not been demonstrated in elasmobranchs and the sensory mechanisms underlying the above movement patterns remain largely speculative. However, they are likely to include responses to water currents, and physical parameters such as temperature, pressure, and the geomagnetic field. Of particular interest in elasmobranchs is that geomagnetic orientation could be mediated directly via a magnetite based sensory system, or indirectly via the electrosensory system. Systematic studies of movement patterns and experimental studies of the underlying mechanisms of orientation are required to gain an increased understanding of orientation and navigation in this intriguing group.     

Can zebra mussels change stratification patterns in a small reservoir?

Colonization and proliferation of zebra mussel (Dreissena polymorpha) population in Hargus lake, a small thermally stratified reservoir in Ohio, U.S.A., caused a significant increase in water clarity and a remarkable decrease in phytoplankton biomass during the period from 1993 to 1995. Increased light penetration and reduced organic matter loading to the meta-and hypolimnion were reflected in the lake stratification patterns, particularly in the temperature and oxygen profiles in the metalimnion. The meta- and hypolimnetic water temperature increased significantly over three years, irrespective of variation in surface water temperature. The epilimnion depth (mixing depth) increased by about the same magnitude as did the average Secchi depth. However, the total heat content of the lake did not show a consistent trend to increasing zebra mussel abundance, as it was largely influenced by the temperature of the large water volumes near the surface, which were in turn affected by weather conditions. Concurrent with the thermal structure change, the dissolved oxygen structure also changed over three years, though to a lesser extent. The changes in oxygen stratification pattern were reflected by increased oxygen concentrations in the metalimnion and a lowered depth of 3 mg l^–1 DO isopleth. These observed changes were likely attributed to increased water mixing depth, metalimnion photosynthesis and reduced oxygen consumption by organic matter. With increased epilimnion thickness and improved oxygen conditions in the metalimnion, the habitable space for aquatic macro-organisms (including fish) expanded substantially. Our results suggest that the indirect impacts of zebra mussels on small lake stratification patterns may have much broader implications than do the direct trophic interactions to the whole ecosystem.     

P-bodies and mitochondria: Which place in RNA interference?

Micro-RNAs (miRNAs) are major actors of RNA interference (RNAi), a regulation pathway which leads to translational repression and/or degradation of specific mRNAs. They provide target specificity by incorporating into the RISC complex and guiding its binding to mRNA. Since the discovery of RNAi, many progresses have been made on the mechanism of action of the RISC complex and on the identification of target mRNAs. However, the regulation of RNAi has been poorly investigated so far. Recently, various studies have revealed physical and functional relationships between RNAi, P-bodies and mitochondria. This review intends to recapitulate these data and discuss their potential importance in cell metabolism.     

Ramadan fasting alters endocrine and neuroendocrine circadian patterns. Meal-time as a synchronizer in humans?

Muslims must refrain from eating, drinking, smoking, and sexual relations from sunrise to sunset during the month of Ramadan. Serum concentrations of melatonin, steroid hormones (cortisol, testosterone), pituitary hormones (prolactin, LH, FSH, GH, TSH) and thyroid hormones (free thyroxin and free triiodothyronine) were documented around the clock at six 4-hourly intervals before Ramadan began and on the twenty-third day of Ramadan (daytime fasting). Time series were analysed with repeated measures ANOVA. Statistically significant differences were found in some variables: the nocturnal peak of melatonin was diminished and may have been delayed; there was a shift in the onset of cortisol and testosterone secretion; the evening peak of prolactin was enhanced, FSH and GH rhythmic patterns were affected little or not at all by Ramadan fasting and only the serum TSH rhythm was blunted over the test time span. These data show that daytime fasting, modifications in sleep schedule and psychological and social habits during Ramadan induce changes in the rhythmic pattern of a number of hormonal variables.     

Do freshwater ecoregions and continental shelf width predict patterns of historical gene flow in the freshwater fish Poecilia butleri?

We examined historical patterns of gene flow in the freshwater fish Poecilia butleri in western Mexico. We tested the hypothesis that the boundaries between four freshwater ecological communities (ecoregions) might have limited the movement of P. butleri because changes in species compositions might restrict establishment between adjacent ecoregions, even in situations where a physical barrier is absent. Hence, we predicted that boundaries between ecoregions should correspond to phylogeographical breaks in P. butleri. We also tested the hypothesis that the width of the continental shelf affected historical gene flow in P. butleri because a broad continental shelf provides a greater opportunity for rivers to coalesce during historical episodes of low sea levels as opposed to a narrow continental shelf that should restrict the potential for gene flow among adjacent rivers. Hence, we predicted greater amounts of historical gene flow among neighbouring river basins in the region of western Mexico where the continental shelf is wider, whereas, in the region where the continental shelf is narrower, we expected to detect limited levels of historical gene flow. We analyzed mitochondrial DNA sequence data (cytochrome b) taken from 264 individuals of P. butleri collected from 34 locations distributed across four different ecoregions in western Mexico. To examine patterns of phylogenetic diversification and historical gene flow in P. butleri, we employed several analytical approaches, including traditional tree‐based phylogenetic analyses (likelihood and parsimony), haplotype network reconstruction, analyses of molecular variance, and spatial analysis of molecular variance. We found genetic breaks coinciding with two out of three different ecoregion boundaries, suggesting limited historical gene flow. In addition to different species compositions between these adjacent ecoregions, geological features such as the Trans‐Mexican Volcanic Belt and the mountainous topography in south‐western Mexico, likely contributed to these observed genetic breaks. By contrast, no genetic break was evident between two other ecoregions, a result that partially rejects our first hypothesis. Several results were consistent with our second hypothesis. Changes in the width of the continental shelf in western Mexico are associated with the observed patterns of historical gene flow. Our results indicate that the interactions among multiple geological and biological factors affect the spatial patterns of genetic diversity of widespread freshwater species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 399–416.