A simulation study of subterranean termites' territory formation

The process through which the Formosan subterranean termite, Coptotermes formosanus Shiraki, establishes territory was simulated using a lattice model in order to understand how such territories are formed from their seeds-founding pairs that fall to the ground every year. The model incorporated, summer–winter cycles, and fourteen years were simulated. Simulated pairs fell to random sites within the lattice space at the beginning of every summer, and their territories grew during the summer season, and shrunk during the winter season. Fourteen years were sufficient for territory size and shape to become stable over time. The simulation revealed that only pairs introduced at t = 0 had established large territories by the end of the simulation (t = 14). Pairs that were introduced later expanded their territory a little at first, but ultimately shrunk back into a single-cell-sized or small-sized territory. This means that stable-state territory size is mostly determined by when that territory was initially established.     

Effects of tunnel structures of two termite species on territorial competition and territory size

The foraging territories of 2 subterranean termites, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar), were simulated using a model to explore how territorial intraspecific competition changes with 4 variables characterizing the formation of territory: the number of primary tunnels, N₀; the branching probability, P_branch; the number of territories, N; and the blocking probability, P_block. The blocking probability P_block quantitatively describes the probability that a tunnel will be terminated when another tunnel is encountered; higher P_block values indicate more likely termination. Higher tunnel-tunnel encounters led to denser tunnel networks. We defined a territory as a convex polygon containing a tunnel pattern and explored the effects of competition among termite colonies on territory size distribution at steady state attained after sufficient simulation time. At the beginning of the simulation, N = 10, 20,…, 100 initial territory seeds were randomly distributed within a square area. In our previous study, we introduced an interference coefficient γ to characterize territorial competition. Higher γ values imply higher limitations on network growth. We theoretically derived γ as a function of P_block and N. In this study, we considered the constants in γ as functions of N₀ and P_branch so as to quantitatively examine the effect of tunnel structure on territorial competition. By applying statistical regression to the simulation data, we determined the generalized γ functions for both species. Under competitive conditions, territory size is most strongly affected by N₀, while the outcome of territorial competition is most strongly affected by N, followed by P_block and N₀.     

A maze-lover's dream: Burrow architecture,natural history and habitat characteristics of Ansell's mole-rat (Fukomys anselli)

The Ansell's mole-rat (Fukomys anselli, Bathyergidae) is a small-sized social subterranean rodent whose distribution is confined to the Lusaka area in Zambia. It is an established model species for various laboratory studies, but until now the knowledge of its biology under natural conditions has been limited. Here, we provide the first comprehensive natural history and ecological data on a free living population from Miombo woodland. The Ansell's mole-rat lives in groups of up to 13 individuals (mean 9.7 ± 2.5; N = 9 complete, fully established family groups) with a single breeding pair per group. The family groups occupy very large and complex burrow systems consisting of 0.5–2.8 km of tunnels (mean = 1.2 ± 0.6 km, N = 15), which are densely branched and reticulated especially around nests. Burrow systems of neighbouring family groups were often interconnected by a freely passable tunnel, which has never before been documented in any African mole-rats. Mole-rat food density in the study area was relatively low (10.0 ± 8.4 m^?2) but its biomass was large (457 ± 889 g m^?2). This, together with a relatively workable soil (cone resistance = 529 ± 26 N cm^?2 at the end of June, with 10% soil humidity), indicates moderate ecological conditions, which disagrees with the aridity food-distribution hypothesis (AFDH) considering small body size and sociality in bathyergids adaptations to harsh environments.     

Structure and magnetic properties of a trinuclear nickel(II) complex with benzenetricarboxylate bridge

Novel trinuclear Ni(II) complex [Ni₃(pmdien)₃(btc)(H₂O)₃](ClO₄)₃ · 4H₂O, 1 where pmdien = N,N,N′,N′,N″-pentamethyldiethylenetriamine, H₃btc = 1,3,5-benzenetricarboxylic (trimesic) acid, has been prepared and structurally characterized. Three nickel atoms are bridged by btc trianion and their coordination sphere is completed by three N atoms of pmdien and O atom of the water molecule. The three nickel(II) magnetic centers are equivalent and their coordination spheres are completed to deformed octahedrons. Magnetic susceptibility was measured over the temperature range 1.8–300 K and zJ′ = ?0.19 cm^?1, D = 3.79 cm^?1, g = 2.18 parameters were calculated.     

Population structure and genetic diversity of Dysosma versipellis (Berberidaceae), a rare endemic from China

Dysosma versipellis (Berberidaceae) is an endangered and endemic species in China. To provide scientific foundation for formulating conservation strategies, we sampled six extant populations of this species and assessed the levels and patterns of genetic diversity using ISSR markers (11 primers). Of 144 bands detected 57.64% were polymorphic, but on average only 20.72% were polymorphic within populations. Our results revealed a low level of intraspecific genetic diversity (at population level: H_pop = 0.082, H_B = 0.177, SI = 0.1194; at species level: H_pop = 0.207, H_B = 0.378, SI = 0.3069). A high level of genetic differentiations among populations was detected based on Nei's genetic diversity analysis (60%), AMOVA analysis (65%), and Bayesian analysis (53%). The low levels of heterozygosity and high genetic differentiation observed in D. versipellis may be the consequence of low rate of natural recruitment, clonal growth, gene drift, and habitat fragmentation. Based on this, we suggest that in situ conservation be an important and practical measure for maintaining the genetic diversity of this species. Ex situ conservation should sample from different populations across the distribution range of the species to conserve high genetic diversity.     

Genetic structure of expanding wolf (Canis lupus) populations in Italy and Croatia,and the early steps of the recolonization of the Eastern Alps

After centuries of range contraction and demographic declines wolves are now expanding in Europe, colonizing regions from where they have been absent for centuries. Wolf colonizing the western Alps originate by the expansion of the Italian population. Vagrant wolves of Italian and Dinaric-Balkan origins have been recently observed in the Eastern Alps. In this study we compared the genetic structure of wolf populations in Italy and Croatia, aiming to identify the sources of the ongoing recolonization of the Eastern Alps. DNA samples, extracted from 282 Italian and 152 Croatian wolves, were genotyped at 12 autosomal microsatellites (STR), four Y-linked STR and at the hypervariable part of the mitochondrial DNA control-region (mtDNA CR1). Wolves in Croatia and Italy underwent recent demographic bottlenecks, but they differ in genetic diversity and population structure. Wolves in Croatia were more variable at STR loci (N_A = 7.4, H_O = 0.66, H_E = 0.72; n = 152) than wolves in Italy (N_A = 5.3, H_O = 0.57, H_E = 0.58; n = 282). We found four mitochondrial DNA (mtDNA CR1) and 11 Y-STR haplotypes in Croatian wolves, but only one mtDNA CR1 and three Y-STR haplotypes in Italy. Wolves in Croatia were subdivided into three genetically distinct subpopulations (in Dalmatia, Gorski kotar and Lika regions), while Italian wolves were not sub-structured. Assignment testing shows that the eastern and central Alps are recolonized by wolves dispersing from both the Italian and Dinaric populations. The recolonization of the Alps will predictably continue in the future and the new population will be genetically admixed and very variable with greater opportunities for local adaptations and survival.     

Biased richness and evenness relationships within Shannon–Wiener index values

The purpose of this analysis was to empirically model and graphically illustrate the numerical relationships between richness (S, 4–35 species) and evenness (E) with respect to Shannon–Wiener index (H′, log_e-based) values. Thirty-two richness-based third-order polynomial regression models (R > 0.99, P < 0.001, n = 28–71) were constructed to characterize these relationships. A composite diagram showed richness varied curvilinearly, with steepness increasing and the spacing between curves decreasing with greater evenness and H′. Maximum H′ values for each richness curve were equal to log_e S (when E = 1), whereas minima were approximated by evenness values of ∼1/S (when H′ = 0). It was concluded from multiple and polynomial regression analyses that: (i) evenness contributed more than richness (E:S ≥3:1) to determining H′, based on standardized partial beta-coefficients; (ii) the differential in E:S ratios increased with greater richness; (iii) the patterns of H′ sample variation between maximum unevenness and perfect evenness was convexo-concave shaped; and (iv) richness as an explanatory variable of H′ was likely an artifact of evenness (0–1 scale) being rescaled according to individual H′ maxima. H′ was redefined as a logarithm-weighted measure of evenness at a given level of richness, which means H′ is either an imperfect index of diversity or a biased measure of evenness. It was also found that the fundamental components of the Shannon–Wiener index measure dominance concentration rather than evenness, with the reversal in emphasis due to multiplication of the H′ equation by −1. H′-derived effective species numbers (exp H′, D) increasingly deviated from those of the diversity model D = S × E in response to increasing richness (up to 69% for 35 species), particularly when evenness was between 0.15 and 0.40. Of two cross-validated H′ prediction methods (P < 0.001, n = 325), the collective use of individual richness-based polynomial regression equations (r = 0.954) was better than a single multiple regression model that incorporated a broad spectrum of richness levels (r = 0.882). A simple graphic model was constructed to illustrate patterns of evenness variation as a function of changing richness and H′ values. Based on the identified biases, particularly E:S ratios, it was recommended that use of H′ be discontinued as a basis for assessing diversity in ecological research or, at the very least, accompanied by independent analyzes of richness and evenness.     

Log-relative growth: A new dendrochronological approach to study diameter growth in Cedrela odorata and Juglans neotropica,Central Forest,Peru

Many studies regarding growth in diameter at breast height (D) in trees suffer from several problems, including heteroscedasticity, temporal autocorrelation and very low statistical adjustments. In growth ring studies, growth models are sometimes omitted, presenting only a mean curve or smoothings, while studies that use models often do not address the above mentioned problems. For these reasons, this paper proposes a new approach to the classical modeling of D = f(t), where t is age (years), using the logarithmic transformation of the relative growth rate ln(1/D)(dD/dt) = ln f(D, A),where A is the asymptote of D based on the differential growth rate model of von Bertalanffy. High statistically significant adjustments for Cedrela odorata (ME = 65%, model efficiency, ME, an analogous to R² but for non-linear regressions), and Juglans neotropica (ME = 78%) were obtained and met all regression assumptions. These equations were integrated to obtain D = f(t) for both species, followed by self and independent validation. Based on these equations, different life history and silviculture traits were calculated for both species. This procedure does not appear to have been previously used in the study of tree growth.     

Sperm cryopreservation in guppies and black mollies—A generalized freezing protocol for livebearers in Poeciliidae

In this study, we evaluated various parameters of sperm cryopreservation in two livebearers, guppies (Poecilia reticulata) and black mollies (P. latipinna). Our results suggested a common freezing protocol for the guppies and mollies: suspend sperm in Hanks’ balanced salt solution (HBSS) at 300 mOsm/kg, use 14% glycerol as cryoprotectant, cool at 25 °C/min, and thaw at 40 °C in a water bath for 7 s. Live young were produced from females inseminated with frozen-thawed sperm in both species. In guppies, percent fertilization (F) and the number of embryos (N) produced with cryopreserved sperm (F = 50%, N = 74, from 26 females) were similar to those of fresh controls (F = 54%, N = 61, from 22 females). Interestingly, this same freezing protocol has been used successfully for sperm cryopreservation in green swordtails Xiphophorus helleri, and platyfish of X. couchianus with post-thaw motility as high as 80%. All these species belong to the family of Poeciliidae, and their sperm are similar in morphology exhibiting the absence of acrosome, elongate sperm head, and the long mitochondrial sheaths. Besides their internal fertilization reproduction mode, these fish are also small in size (2–4 cm) and live in a freshwater environment. Sperm cryopreservation in fish has been generally recognized as species specific, and new protocols are required for new species. However, results presented in this study suggested otherwise. Thus, sperm cryopreservation methods optimized for one species may be applicable to others if they are taxonomical closely related species with similar sperm morphology and reproduction mode. Considering the enormous number of fish species on the planet, development of generalized sperm freezing protocols for species in groups could have additional advantages for genetic conservation.     

Gender discrimination in undernutrition with mediating factors among Bengalee school children from Eastern India

This study was undertaken to determine age and sex variations in the prevalence of underweight and stunting, and to assess the impact of some socio-economic variables on undernutrition among 6–16 year old school children of Bengalee ethnicity in Chapra, West Bengal, India. The subjects were selected randomly from various schools and madrassas of the Chapra Block. A total of 725 children (342 boys and 383 girls) aged 6–16 years were measured and data on their socio-economic status were collected. Age and sex combined rates of underweight and stunting were 44.40% and 37.20%, respectively. Weight-for-age Z-score (WAZ) showed significant association with per-capita income (PCI) among boys (F = 5.45) and girls (F = 8.14). Height-for-age Z-score (HAZ) has also shown the association with per-capita income among boys (F = 4.43) and girls (F = 9.69). The WAZ was significantly associated with fathers’ educational status (FOS) (t = ?2.95) and the number of living rooms (NLR) (t = ?2.91) among girls. The HAZ showed significant association with number of siblings (NS) among girls (F = 4.25). Linear regression analyses revealed that NLR (t = 2.04) and NS (t = 1.95) had a significant impact on HAZ among boys. Among girls, PCI (t = 3.38), FOS (t = 2.87) and NLR (t = 2.81) had a significant impact on WAZ and also PCI (t = 3.28) and FOS (t = 2.90) had a significant impact on HAZ. NLR had significant associations with underweight (χ² = 3.59) and stunting (χ² = 4.20) among boys. Among girls, PCI had significant associations with underweight (χ² = 11.15) and stunting (χ² = 11.64). FOS also showed significant associations with underweight (χ² = 8.10) as well as stunting (χ² = 8.28) among girls. NLR showed a significant association with underweight (χ² = 7.75). Logistics regression analyses revealed that FOS (Wald = 8.00) and NLR (Wald = 4.09) were significant predictors of stunting among boys. Among girls, PCI was a significant predictor of underweight (Wald = 10.95) as well as stunting (Wald = 10.45). FOS, NLR and NS were also significant predictors of stunting (Wald = 8.16), underweight (Wald = 7.68) and stunting (Wald = 6.97) respectively. The present study revealed that the nutritional status of the children was unsatisfactory and it is of paramount importance not only to increase the amount of food supplementation given but also to promote gender equality.     

Glucopyranosylidene-spiro-iminothiazolidinone,a new bicyclic ring system: Synthesis,derivatization, and evaluation for inhibition of glycogen phosphorylase by enzyme kinetic and crystallographic methods

The reaction of thiourea with O-perbenzoylated C-(1-bromo-1-deoxy-β-d-glucopyranosyl)formamide gave the new anomeric spirocycle 1R-1,5-anhydro-d-glucitol-spiro-[1,5]-2-imino-1,3-thiazolidin-4-one. Acylation and sulfonylation with the corresponding acyl chlorides (RCOCl or RSO₂Cl where R = tBu, Ph, 4-Me-C₆H₄, 1- and 2-naphthyl) produced the corresponding 2-acylimino- and 2-sulfonylimino-thiazolidinones, respectively. Alkylation by MeI, allyl-bromide and BnBr produced mixtures of the respective N-alkylimino- and N,N′-dialkyl-imino-thiazolidinones, while reactions with 1,2-dibromoethane and 1,3-dibromopropane furnished spirocyclic 5,6-dihydro-imidazo[2,1-b]thiazolidin-3-one and 6,7-dihydro-5H-thiazolidino[3,2-a]pyrimidin-3-one, respectively. Removal of the O-benzoyl protecting groups by the Zemplén protocol led to test compounds most of which proved micromolar inhibitors of rabbit muscle glycogen phosphorylase b (RMGPb). Best inhibitors were the 2-benzoylimino- (K_i = 9 μM) and the 2-naphthoylimino-thiazolidinones (K_i = 10 μM). Crystallographic studies of the unsubstituted spiro-thiazolidinone and the above most efficient inhibitors in complex with RMGPb confirmed the preference and inhibitory effect that aromatic (and especially 2-naphthyl) derivatives show for the catalytic site promoting the inactive conformation of the enzyme.     

One- and two-dimensional copper benzenedicarboxylate coordination polymers incorporating the flexible tethering diimine N,N′-bis(3-pyridylmethyl)piperazine: Synthesis,structure, and thermal properties

A family of three copper benzenedicarboxylate coordination polymers has been constructed using the conformationally flexible and hydrogen-bonding capable tethering ligand N,N′-bis(3-pyridylmethyl)piperazine (3-bpmp). These three coordination polymers have been characterized via single crystal X-ray diffraction, infrared spectroscopy and elemental and thermogravimetric analysis. {[Cu(ph)(Hph)(H3-bpmp)(H₂O)] · 3H₂O} (1, ph = phthalate) manifests a 1-D chain motif held into a pseudo 3-D supramolecular structure through hydrogen bonding. While both {[Cu(ip)(3-bpmp)(H₂O)] · 2H₂O} (2, ip = isophthalate) and [Cu(tp)(3-bpmp)] (3, tp = terephthalate) exhibit 2-D (4,4) rhomboid grid-like layers, they possess different layer stacking patterns and supramolecular interactions due to coordination geometry variances.     

72/74As-labeling of HPMA based polymers for long-term in vivo PET imaging

In the context of molecular imaging, various polymers based on the clinically approved N-(2-hydroxypropyl)-methacrylamide (HPMA) have been radio-labeled using longer-living positron emitters ⁷²As t_1/2 = 26 h or ⁷⁴As t_1/2 = 17.8 d. This approach may lead to non-invasive determination of the long-term in vivo fate of polymers by PET (positron emission tomography). Presumably, the radio label itself will not strongly influence the polymer structure due to the fact that the used nuclide binds to already existing thiol moieties within the polymer structure. Thus, the use of additional charges or bulky groups can be avoided.     

Synthesis,EPR, electrochemistry and EXAFS studies of ruthenium(III) complexes with a symmetrical tetradentate N2O2 Schiff base

A series of new hexa-coordinated ruthenium(III) complexes of the type [RuX(Nap-o-phd)(EPh₃)] (where, H₂-Nap-o-phd = N,N′-bis(2-hydroxy-1-naphthaldehyde) o-phenylene diamine; X = Cl or Br; E = P or As) have been prepared by reacting [RuX₃(EPh₃)₃] and [RuBr₃(PPh₃)₂(MeOH)] (where X = Cl or Br; E = P or As) with tetradentate Schiff base ligand (H₂-Nap-o-phd) in 1:1 molar ratio. The complexes have been characterized by elemental analyses, infra red, electronic, electron paramagnetic resonance spectroscopy and cyclic voltammetry. The coordination geometry and structure of the complexes have been investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy and an octahedral structure has been proposed.     

Methyl-palladium(II) complexes of pyridine-bridged bis(nucleophilic heterocyclic carbene) ligands: Substituent effects on structure,stability, and catalytic performance

A series of discrete, mononuclear palladium(II)–methyl complexes, together with several palladium(II)–chloro analogues, of pyridine-functionalised bis-NHC ligands have been prepared via ligand transmetallation from the silver(I)-NHC complexes. The reported complexes comprise examples with both the methylene-bridged 2,6-bis[(3-R-imidazolin-2-yliden-1-yl)methyl]pyridine (_RC^∧N^∧C; R = Mes, dipp, ^tBu) and planar 2,6-bis(3-R-imidazolin-2-yliden-1-yl)pyridine (_RCNC; R = Mes, dipp) ligands and, when combined with the previously reported _MeC^∧N^∧C/_MeCNC examples, cover a broad spectrum of ligand substituent steric and electronic properties, including the bulky Mes and dipp groups frequently used in catalytic applications. The palladium(II) complexes have been characterised by a variety of methods, including single crystal X-ray crystallography, with the shielding of the Pd–Me groups in the proton NMR spectra of some of the N-aryl substituted examples correlated with the proximity of the aryl rings to the methyl group in the solid state structures. The [PdMe(_RC^∧N^∧C/_RCNC)]⁺ complexes undergo thermal degradation via reductive methyl-NHC coupling to give 2-methyl-3-R-imidazolium-1-yl species with relative stabilities in the order of [PdMe(_MesC^∧N^∧C)]BF₄ > [PdMe(_MeC^∧N^∧C)]BF₄ ≈ [PdMe(_MesCNC)]BF₄ > [PdMe(_MeCNC)]BF₄ > [PdMe(_tBuC^∧N^∧C)]BF₄ ≫ [PdMe(_tBuCNC)]BF₄ (not isolable). A comparison of the activity of the complexes as precatalysts in a model Heck coupling reaction shows greatest activity in those species bearing bulkier N-substituents, with complexes bearing _RC^∧N^∧C ligands generally more efficient precatalysts than those bearing _RCNC ligands.     

Association of urinary 15-F2t-isoprostane level with oxygen desaturation and carotid intima–media thickness in nonobese sleep apnea patients

Obstructive sleep apnea (OSA) is characterized by recurrent apnea during sleep that may unbalance oxidative stress, increasing atherosclerosis. Among oxidative stress markers, 15-F_2t-isoprostane is considered one of the most sensitive and specific metabolites of lipid peroxidation. To explore the relationship between urinary 15-F_2t-isoprostane with sleep apnea severity and carotid modifications in nonobese OSA patients, 31 nonobese sleep apnea patients were studied, along with 10 lean subjects without OSA. Patients were assessed by polysomnography, blood pressure measurement, and ultrasonography to determine the carotid intima–media thickness (IMT). Urinary 15-F_2t-isoprostanes were measured by liquid chromatography–tandem mass spectrometry. Urinary 15-F_2t-isoprostane concentrations were increased in severe OSA patients compared to control subjects (20.2 ± 7.3 vs 12.3 ± 2.8 ng/mmol creatinine; P = 0.020). Mean carotid IMT was correlated with 15-F_2t-isoprostane (r = 0.532; P < 0.001) and with the apnea–hypopnea index (r = 0.345; P = 0.029). 15-F_2t-Isoprostane level was related to the night time spent at SaO₂ < 90% (r = 0.478; P = 0.002), the apnea–hypopnea index (r = 0.465; P = 0.003), and the mean nocturnal SaO₂ (r = ? 0.424; P = 0.007). These results showed a relationship between lipid peroxidation, carotid intima–media thickness, and intermittent hypoxia in nonobese OSA patients, thus reinforcing the hypothesis that oxidative stress could be involved in the early atherosclerotic process.     

Low-mass molecular dynamics simulation for configurational sampling enhancement: More evidence and theoretical explanation

It has been reported recently that classical, isothermal–isobaric molecular dynamics (NTP MD) simulations at a time step of 1.00 fs of the standard-mass time (Δt=1.00 fs^smt) and a temperature of ≤340 K using uniformly reduced atomic masses by tenfold offers better configurational sampling than standard-mass NTP MD simulations at the same time step. However, it has long been reported that atomic masses can also be increased to improve configurational sampling because higher atomic masses permit the use of a longer time step. It is worth investigating whether standard-mass NTP MD simulations at Δt=2.00 or 3.16 fs^smt can offer better or comparable configurational sampling than low-mass NTP MD simulations at Δt=1.00 fs^smt. This article reports folding simulations of two β-hairpins showing that the configurational sampling efficiency of NTP MD simulations using atomic masses uniformly reduced by tenfold at Δt=1.00 fs^smt is statistically equivalent to and better than those using standard masses at Δt=3.16 and 2.00 fs^smt, respectively. The results confirm that, relative to those using standard masses at routine Δt=2.00 fs^smt, the low-mass NTP MD simulations at Δt=1.00 fs^smt are a simple and generic technique to enhance configurational sampling at temperatures of ≤340 K.     

5-((1-Aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones as potential anticancer agents with anti-inflammatory properties

A series of novel 5-((1-aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones (3a–z) have been evaluated for in vitro cytotoxicity against a panel of 60 human tumor cell lines. Compound 3k exhibited the most potent growth inhibition against melanoma MDA-MB-435 cells (GI₅₀ = 850 nM), against leukemia SR cancer cells (GI₅₀ = 1.45 μM), and OVCAR-3 (GI₅₀ = 1.26 μM) ovarian cancer cell lines. The structurally related compound 3s had a GI₅₀ value of 1.77 μM against MDA-MB-435 cells. The N-naphthoyl analogue 3t had GI₅₀ values of 1.30 and 1.91 μM against HOP-92 non-small cell lung cancer and MDA-MB-435 melanoma cell lines, respectively. The related analogue 3w had GI₅₀ values of 1.09 μM against HOP-92 non-small cell lung cancer cell lines. Interestingly, docking of the two active molecules 3k and 3w into the active site of COX-2 indicates that these compounds are COX-2 ligands with strong hydrophobic and hydrogen bonding interactions. Thus, compounds 3k, 3t, 3s, and 3w constitute a new class of anticancer/anti-inflammatory agents that may have unique potential for cancer therapy.     

Altitude modifies species richness–nutrient indicator value relationships in a country-wide survey of grassland vegetation

Nutrient enrichment is a threat to botanical diversity in Europe, and its assessment is part of biodiversity monitoring schemes. In Switzerland, this is done by calculating the average nutrient (N) indicator value of the vegetation based on a country-wide systematic vegetation survey. However, it is questionable whether N values indicate eutrophication and resulting species loss equally well across an entire country, which includes wide topographic gradients and distinct biogeographic regions. Here we analyze vascular plant species lists from 415 grassland plots (10 m²) between 365 and 2770 m a.s.l. throughout Switzerland to investigate how the relationship between N value and species richness differs with altitude and among regions. The N value strongly decreased with altitude (piecewise regression: r² = 0.77), particularly between 800 and 2000 m a.s.l., where this decrease was related to a decreasing proportion of fertilized grasslands. In the alpine belt, lower N values were associated with a greater frequency of acidic soils and a restricted species pool. Vascular plant species richness was maximal at intermediate altitude (piecewise regression: r² = 0.33) and intermediate N value (polynomial regression: r² = 0.46). When analyzed separately by altitudinal belt, the relationship between species richness and N value was negative in the lowlands and montane belt but unimodal in the subalpine belt. In the alpine belt, soil pH (R indicator values) explained most of the variation in species richness. Two indices of between-plot diversity (floristic dissimilarity and the contribution of individual plots to total species richness) were negatively related to N values from the lowlands to the subalpine belt but not in the alpine belt. All relationships differed little among the biogeographic regions of Switzerland, but they might be modified by changes in management and by the expansion of common lowland species into mountain grasslands.