Microwave‐assisted water extraction of green tea polyphenols

Introduction – Green tea, a popular drink with beneficial health properties, is a rich source of specific flavanols (polyphenols). There is a special interest in the water extraction of green tea polyphenols since the composition of the corresponding extracts is expected to reflect the one of green tea infusions consumed worldwide. Objective – To develop a microwave‐assisted water extraction (MWE) of green tea polyphenols. Methodology – MWE of green tea polyphenols has been investigated as an alternative to water extraction under conventional heating (CWE). The experimental conditions were selected after consideration of both temperature and extraction time. The efficiency and selectivity of the process were determined in terms of extraction time, total phenolic content, chemical composition (HPLC‐MS analysis) and antioxidant activity of the extracts. Results – By MWE (80°C, 30 min), the flavanol content of the extract reached 97.46 (± 0.08) mg of catechin equivalent/g of green tea extract, vs. only 83.06 (± 0.08) by CWE (80°C, 45 min). In particular, the concentration of the most bioactive flavanol EGCG was 77.14 (± 0.26) mg of catechin equivalent/g of green tea extract obtained by MWE, vs 64.18 (± 0.26) mg/g by CWE. Conclusion – MWE appears more efficient than CWE at both 80 and 100°C, particularly for the extraction of flavanols and hydroxycinnamic acids. Although MWE at 100°C typically affords higher yields in total phenols, MWE at 80°C appears more convenient for the extraction of the green tea‐specific and chemically sensitive flavanols. Copyright © 2009 John Wiley & Sons, Ltd.     

The so‐called primitive genera of Genisteae (Fabaceae): systematic and phyletic considerations based on karyological data

A karyological analysis of the so‐called primitive genera of Genisteae has shown that they have a relatively homogeneous chromosome complement: all species tend to have a somatic chromosome number 2n = 48, which can increase to 2n = 52, presumably as a result of hyperaneuploidy. Karyological data suggest that Argyrocytisus, Cytisophyllum and Petteria may be considered as distinct genera rather than being assigned to Cytisus, with 2n = 52 for the first of these and 2n = 50 for the other two genera. They may be interpreted as relict monotypic genera as a result of the presence of a stabilized aneuploidy. Karyological characters exclude a recent origin of Genisteae from Thermopsideae. On the contrary, they are consistent with the hypothesis that Genisteae and Thermopsideae are independently derived from a basic papilionoid stock, of which present day Sophoreae are the remainder. At least two lines would lead from Sophoreae to the taxa of the ‘genistoid alliance’, one to Thermopsideae and the other ‘podalyrioid alliances’ (Podalyrieae and Mirbelieae), with the prevailing basic number of x = 9, and the other to Genisteae, with a basic number of x = 12 persisting in some present day genera, including Cytisus s.l. From this lineage, a wide range of secondary basic numbers has been formed, mostly by descending aneuploidy. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 232–248.     

Effects of depth and bottom communities on the distribution of highly territorial reef fish in the northwestern region of Cuba

The main goal of the study was to investigate changes in reef fish species abundance and its correlation with selected environmental variables. Three main questions guided the analyses: (i) Do the analytical methods have a significant influence on the results; (ii) What are the main assemblage variation axes; and (iii) What are the factors correlating best with assemblage composition. Highly territorial fish assemblages of several coral reefs along the northwestern region of Cuba were assessed using a stationary point visual census technique. A total of 39 701 individuals of 26 species from the families Chaetodontidae, Labridae and Pomacentridae were counted in 841 censuses; almost 80% of the fish belonged to just four species: bluehead (Thalassoma bifasciatum), bicolor damselfish (Stegastes partitus), slippery dick (Halichoeres bivittatus) and blue chromis (Chromis cyanea). Several multivariate techniques (cluster analysis, non‐metric multidimensional scaling and canonical correspondence analysis) were used to explore main patterns in assemblage composition variation. It was found that the results did not differ significantly when analyzing the same data set. Furthermore, it was shown that the combined use of different multivariate techniques enhanced the interpretation of fish assemblage composition changes. Depth was the main variable explaining variation in the composition of fish assemblages in the studied reefs. The densities of corals and gorgonians were also strongly associated with depth. Sponge density made an additional significant contribution to the explanatory model. Results of this research could be used as a baseline reference for future analyses of the impact of human actions in the study area. (e.g. oil spills, change in fishing intensity, other pollution events, tourism development).     

MICROMORPHOGENESIS DURING DIATOM WALL FORMATION PRODUCES SILICEOUS NANOSTRUCTURES WITH DIFFERENT PROPERTIES1

Micromorphogenesis within the silica deposition vesicle (SDV) of the diatom Pinnularia viridis (Nitzsh) Ehrenb. resulted in distinct silica nanostructures and layers within forming valves and girdle bands. These siliceous components were similarly disclosed following alkaline etching of mature valves/girdle bands, where their different susceptibilities to dissolution over time resulted from apparent differences in silica density and/or chemistry. The bulk of silica appeared to be deposited at the interface of the forming valve or girdle band with the silicalemma and occurred by the outward expansion of microfibrils of silica that aligned perpendicularly to the silicalemma. Microfibrils originated from both sides of the “silica lamella,” the first nanostructure formed within the SDV, and several silica species of distinct nanostructure and density resulted, including distinctive inner and outermost silica “coverings” of mature valves/girdle bands and the central and terminal nodules. Not all silica deposition and micromorphogenesis occurred in contact with the expanding silicalemma, but was somehow directed within the SDV cavity, and resulted in the distinct silica layers that lined the raphe fissures and poroids. Following alkaline etching, the inner surfaces of valves/girdle bands, as well as the silica layers lining the raphes, poroids, and slits, were determined to be significantly more resistant to alkaline etching than the exterior surfaces, while the outer silica coating and the nodules were quickly dissolved. The processes of micromorphogenesis must have exerted precise control over the chemical nature of the silica formed at different positions within the SDV and affected the overall structure and function of the diatom wall.     

What shapes Eurasian lynx distribution in human dominated landscapes: selecting prey or avoiding people?

In the multi-use landscape of southern Norway, the distribution of lynx is likely to be determined both by the abundance of their favoured prey – the roe deer – and the risk associated with the presence of humans because most lynx mortalities are caused by humans (recreational harvest, poaching, vehicle collisions). We described the distribution of the reproductive portion of the lynx population based on snow-track observations of females with dependent kittens collected over 10  yr (1997–2006) in southern Norway. We used the ecological-niche factor analysis to examine how lynx distribution was influenced by roe deer, human activity, habitat type, environmental productivity and elevation. Our first prediction that lynx should be found in areas of relatively high roe deer abundance was supported. However, our second prediction that lynx should avoid human activity was rejected, and lynx instead occupied areas more disturbed in average than those available (with the exception of the most densely occupied areas). Lynx, however, avoided the most disturbed areas and our third prediction of a trade-off between abundance of prey and avoidance of human activity was supported. On the one hand, roe deer in the most disturbed areas benefit to a large extent from current human land use practices, potentially allowing them to escape predation from lynx. On the other hand, the situation is not so favourable for the predators who are restricted in competition refuges with medium to low prey densities. The consequence is that lynx conservation will have to be achieved in a human modifed environment where the potential for a range of conflicts and high human-caused mortality will remain a constant threat.     

Target cell contact suppresses neurite outgrowth from soma–soma paired Lymnaea neurons

Neurite extension from developing and/or regenerating neurons is terminated on contact with their specific synaptic partner cells. However, a direct relationship between the effects of target cell contact on neurite outgrowth suppression and synapse formation has not yet been demonstrated. To determine whether physical/synaptic contacts affect neurite extension from cultured cells, we utilized soma–soma synapses between the identified Lymnaea neurons. A presynaptic cell (right pedal dorsal 1, RPeD1) was paired either with its postsynaptic partner cells (visceral dorsal 4, VD4, and Visceral dorsal 2, VD2) or with a non‐target cell (visceral dorsal 1, VD1), and the interactions between their neurite outgrowth patterns and synapse formation were examined. Specifically, when cultured in brain conditioned medium (CM, contains growth‐promoting factors), RPeD1, VD4, and VD2 exhibited robust neurite outgrowth within 12–24 h of their isolation. Synapses, similar to those seen in vivo, developed between the neurites of these cells. RPeD1 did not, however, synapse with its non–target cell VD1, despite extensive neuritic overlap between the cells. When placed in a soma–soma configuration (somata juxtaposed against each other), appropriate synapses developed between the somata of RPeD1 and VD4 (inhibitory) and between RPeD1 and VD2 (excitatory). Interestingly, pairing RPeD1 with either of its synaptic partner (VD4 or VD2) resulted in a complete suppression of neurite outgrowth from both pre‐ and postsynaptic neurons, even though the cells were cultured in CM. A single cell in the same dish, however, extended elaborate neurites. Similarly, a postsynaptic cell (VD4) contact suppressed the rate of neurite extension from a previously sprouted RPeD1. This suppression of the presynaptic growth cone motility was also target cell contact specific. The neurite suppression from soma–soma paired cells was transient, and neuronal sprouting began after a delay of 48–72 h. In contrast, when paired with VD1, both RPeD1 and this non‐target cell exhibited robust neurite outgrowth. We demonstrate that this neurite suppression from soma–soma paired cells was target cell contact/synapse specific and Ca²⁺ dependent. Specifically, soma–soma pairing in CM containing either lower external Ca²⁺ concentration (50% of its control level) or Cd²⁺ resulted in robust neurite outgrowth from both cells; however, the incidence of synapse formation between the paired cells was significantly reduced. Taken together, our data show that contact (physical and/or synaptic) between synaptic partners strongly influence neurite outgrowth patterns of both pre‐ and postsynaptic neurons in a time‐dependent and cell‐specific manner. Moreover, our data also suggest that neurite outgrowth and synapse formation are differentially regulated by external Ca²⁺ concentration. © 2000 John Wiley & Sons, Inc. J Neurobiol 42: 357–369, 2000     

Bayesian Estimation Using Ranked Set Sampling

Bayesian Estimation of the parameter of a distribution is considered using Ranked set sampling (RSS). It is shown that for at least one RSS plan, the Bayes estimator has smaller Bayes risk than the Bayes estimator using simple random sampling (SRS). Furthermore, for exponential family with conjugate prior, the Bayes estimator of the mean using balanced RSS dominates, in terms of its Bayes risk, the Bayes estimator of the mean using SRS. This procedure is used to estimate the average Milk yield of four hundreds and two sheep. The empirical efficiency supports the theoretical findings.     

Global patterns in the shape of species geographical ranges reveal range determinants

Aim Do species range shapes follow general patterns? If so, what mechanisms underlie those patterns? We show for 11,582 species from a variety of taxa across the world that most species have similar latitudinal and longitudinal ranges. We then seek to disentangle the roles of climate, extrinsic dispersal limitation (e.g. barriers) and intrinsic dispersal limitation (reflecting a species’ ability to disperse) as constraints of species range shape. We also assess the relationship between range size and shape. Location Global. Methods Range shape patterns were measured as the slope of the regression of latitudinal species ranges against longitudinal ranges for each taxon and continent, and as the coefficient of determination measuring the degree of scattering of species ranges from the 1:1 line (i.e. latitudinal range = longitudinal range). Two major competing hypotheses explaining species distributions (i.e. dispersal or climatic determinism) were explored. To this end, we compared the observed slopes and coefficients of determination with those predicted by a climatic null model that estimates the potential range shapes in the absence of dispersal limitation. The predictions compared were that species distribution shapes are determined purely by (1) intrinsic dispersal limitation, (2) extrinsic dispersal limitations such as topographic barriers, and (3) climate. Results  Using this methodology, we show for a wide variety of taxa across the globe that species generally have very similar latitudinal and longitudinal ranges. However, neither neutral models assuming random but spatially constrained dispersal, nor models assuming climatic control of species distributions describe range shapes adequately. The empirical relationship between the latitudinal and longitudinal ranges of species falls between the predictions of these competing models. Main conclusions We propose that this pattern arises from the combined effect of macroclimate and intrinsic dispersal limitation, the latter being the major determinant among restricted‐range species. Hence, accurately projecting the impact of climate change onto species ranges will require a solid understanding of how climate and dispersal jointly control species ranges.