Complete genome sequence of the obligate piezophilic hyperthermophilic archaeon Pyrococcus yayanosii CH1

Pyrococcus yayanosii CH1 is the first obligate piezophilic hyperthermophilic archaeon isolated from the deep-sea hydrothermal site Ashadze on the mid-Atlantic ridge at a depth of 4,100 m. This organism grows within a temperature range of 80 to 108°C and a hydrostatic pressure range of 20 to 120 MPa, with optima at 98°C and 52 MPa, respectively. Here, we report the complete genome sequence (1,716,817 bp, with a G+C content of 51.6%) of the type strain P. yayanosii CH1(T) (= JCM 16557). This genomic information reveals a systematic view of the piezoadaptation strategy and evolution scenario of metabolic pathways in Thermococcales.     

Fluid shear stress‐induced JNK activity leads to actin remodeling for cell alignment

Fluid shear stress (FSS) exerted on endothelial cell (EC) surfaces induces actin cytoskeleton remodeling through mechanotransduction. This study was designed to determine whether FSS activates Jun N‐terminal kinase (JNK), to examine the spatial and temporal distribution of active JNK relative to the actin cytoskeleton in ECs exposed to different FSS conditions, and to evaluate the effects of active JNK on actin realignment. Exposure to 15 and 20 dyn/cm² FSS induced higher activity levels of JNK than the lower 2 and 4 dyn/cm² flow conditions. At the higher FSS treatments, JNK activity increased with increasing exposure time, peaking 30 min after flow onset with an eightfold activity increase compared to cells in static culture. FSS‐induced phospho‐JNK co‐localized with actin filaments at cell peripheries, as well as with stress fibers. Pharmacologically blocking JNK activity altered FSS‐induced actin structure and distribution as a response to FSS. Our results indicate that FSS‐induced actin remodeling occurs in three phases, and that JNK plays a role in at least one, suggesting that this kinase activity is involved in mechanotransduction from the apical surface to the actin cytoskeleton in ECs. J. Cell. Physiol. 226: 110–121, 2010. © 2010 Wiley‐Liss, Inc.     

Dry conditions disrupt terrestrial–aquatic linkages in northern catchments

Aquatic ecosystems depend on terrestrial organic matter (tOM) to regulate many functions, such as food web production and water quality, but an increasing frequency and intensity of drought across northern ecosystems is threatening to disrupt this important connection. Dry conditions reduce tOM export and can also oxidize wetland soils and release stored contaminants into stream flow after rainfall. Here, we test whether these disruptions to terrestrial–aquatic linkages occur during mild summer drought and whether this affects biota across 43 littoral zone sites in 11 lakes. We use copper (Cu) and nickel (Ni) as representative contaminants, and measure abundances of Hyalella azteca, a widespread indicator of ecosystem condition and food web production. We found that tOM concentrations were reduced but correlations with organic soils (wetlands and riparian forests) persisted during mild drought and were sufficient to suppress labile Cu concentrations. Wetlands, however, also became a source of labile Ni to littoral zones, which was linked to reduced abundances of the amphipod H. azteca, on average by up to 70 times across the range of observed Ni concentrations. This reveals a duality in the functional linkage of organic soils to aquatic ecosystems whereby they can help buffer the effects of hydrologic disconnection between catchments and lakes but at the cost of biogeochemical changes that release stored contaminants. As evidence of the toxicity of trace contaminant concentrations and their global dispersion grows, sustaining links among forests, organic soils and aquatic ecosystems in a changing climate will become increasingly important.     

Perfect Terahertz Absorption with Graphene Surface Plasmons in the Modified Otto Configuration

Perfect terahertz (THz) absorption in the modified Otto configuration with the insertion of monolayer graphene sheet has been numerically demonstrated. This perfect absorption originates from the enhancement of the electrical field owing to the excitation of the transverse magnetic (TM) polarized surface plasmons at the interface of two dielectrics with monolayer graphene. It is found that the absorption peak occurs at the specific incident angles, which can be employed for realizing the angular absorbers. We further demonstrate that the angle of the peak absorption and the corresponding wavelength can be manipulated by changing the Fermi energy of monolayer graphene sheet via electrostatic biasing. Moreover, the behaviors of the perfect absorption are strongly dependent on the dielectric constants and thicknesses of the surrounding dielectrics.     

Pelagostrobilidium liui n. sp. (Ciliophora,Choreotrichida) from the Coastal Waters of Northeastern Taiwan and an Improved Description of Pelagostrobilidium minutum Liu et al., 2012

The number of somatic kineties in Pelagostrobilidium ranges from 4 to 6 according to the present state of knowledge. This study investigates Pelagostrobilidium liui n. sp. using live observation, protargol stain, and small subunit rDNA data sequencing. Pelagostrobilidium liui n. sp. is characterized by having a spherical‐shaped body, four somatic kineties, with kinety 2 spiraled around the left side of body, about six elongated external membranelles, and invariably no buccal membranelle. It differs from its most similar congener, Pelagostrobilidium minutum Liu et al., 2012 , in (i) cell shape; (ii) macronucleus width; (iii) oral apparatus; (iv) anterior orientation of kinety 2; (v) location where kinety 2 commences; (vi) arrangement of kinety 1; (vii) distance between the anterior cell end and the locations where kineties commence; and (viii) the presence of 12 different bases (including two deletions) in the small subunit rDNA sequences. The diagnosis of P. minutum Liu et al., 2012 is also improved to include the following new characteristics: invariably four somatic kineties; kineties 2 and 4 alone commence at the same level; kinety 2 originates from right anterior cell half on ventral side, extends sinistrally posteriorly, over kinety 1, around left posterior region, terminates near posterior cell end on dorsal side; kinety 1 commences below anterior third of kinety 2.     

Fitness consequences of altering floral circadian oscillations for Nicotiana attenuata

Ecological interactions between flowers and pollinators are all about timing.Flower opening/closing and scent emissions are largely synchronized with pollinator activity,and a circadian clock regulates these rhythms.However,whether the circadian clock increases a plant's reproductive success by regulating these floral rhythms remains untested.Flowers of Nicotiana attenuata,a wild tobacco,diurnally and rhythmically open,emit scent and move vertically through a 140° arc to interact with nocturnal hawkmoths.We tethered flowers to evaluate the importance of flower positions for Manduca sexta-mediated pollinations;flower position dramatically influenced pollination.We examined the pollination success of phase-shifted flowers,silenced in circadian clock genes,NaZTL,NaLHY,and NaTOCi,by RNAi.Circadian rhythms in N.attenuata flowers are responsible for altered seed set from outcrossed pollen.     

Insecticide resistance,associated mechanisms and fitness aspects in two Brazilian Stegomyia aegypti (= Aedes aegypti) populations

In Brazil, insecticide resistance in Stegomyia aegypti (= Aedes aegypti) (Diptera: Culicidae) populations to pyrethroids and to the organophosphate (OP) temephos is disseminated. Currently, insect growth regulators (IGRs) and the OP malathion are employed against larvae and adults, respectively. Bioassays with mosquitoes from two northeast municipalities, Crato and Aracaju, revealed, in both populations, susceptibility to IGRs and malathion (RR₉₅ ≤ 2.0), confirming the effectiveness of these compounds. By contrast, temephos and deltamethrin (pyrethroid) resistance levels were high (RR₉₅ > 10), which is consistent with the use of intense chemical control. In Crato, RR₉₅ values were > 50 for both compounds. Knock‐down‐resistant (kdr) mutants in the voltage‐gated sodium channel, the pyrethroid target site, were found in 43 and 32%, respectively, of Aracaju and Crato mosquitoes. Biochemical assays revealed higher metabolic resistance activity (esterases, mixed function oxidases and glutathione‐S‐transferases) at Aracaju. With respect to fitness aspects, mating effectiveness was equivalently impaired in both populations, but Aracaju mosquitoes showed more damaging effects in terms of longer larval development, decreased bloodmeal acceptance, reduced engorgement and lower numbers of eggs laid per female. Compared with mosquitoes in Crato, Aracaju mosquitoes exhibited lower OP and pyrethroid RR₉₅, increased activity of detoxifying enzymes and greater effect on fitness. The potential relationship between insecticide resistance mechanisms and mosquito viability is discussed.     

Functional flower traits and their diversity drive pollinator visitation

Recent studies have shown that the diversity of flowering plants can enhance pollinator richness and visitation frequency and thereby increase the resilience of pollination. It is assumed that flower traits explain these effects, but it is still unclear which flower traits are responsible, and knowing that, if pollinator richness and visitation frequency are more driven by mass‐ratio effects (mean trait values) or by trait diversity. Here, we analyse a three‐year data set of pollinator observations collected in a European grassland plant diversity experiment (The Jena experiment). The data entail comprehensive flower trait measurements, including reward traits (nectar and pollen amount), morphological traits (height, symmetry, area, colour spectra) and chemical traits (nectar‐amino acid and nectar‐sugar concentration). We test if pollinator species richness and visitation frequency of flower communities depend on overall functional diversity combining all flower traits within a community, single trait diversities (within trait variation) and community‐weighted means of the single traits, using Bayesian inference. Overall functional diversity did not affect pollinator species richness, but reduced visitation frequency. When looking at individual flower traits separately, we found that single trait diversity of flower reflectance and flower morphology were important predictors of pollinator visitation frequency. Moreover, independent of total flower abundance, community‐weighted means of flower height, area, reflectance, nectar‐sugar concentration and nectar‐amino acid concentration strongly affected both pollinator species richness and visitation frequency. Our results, challenge the idea that functional diversity always positively affects ecosystem functions. Nonetheless, we demonstrate that both single trait diversity and mass‐ratio effects of flower traits play an important role for diverse and frequent flower visits, which underlines the functionality of flower traits for pollination services.