Minor Alteration Research Articles

Binding of chloroquine–conjugated gold nanoparticles with bovine serum albumin

We have conjugated chloroquine, an anti-malarial, antiviral and anti-tumor drug, with thiol-functionalized gold nanoparticles and studied their binding interaction with bovine serum albumin (BSA) protein. Gold nanoparticles have been synthesized using sodium borohydride as reducing agent and 11-mercaptoundecanoic acid as thiol functionalizing ligand in aqueous medium. The formation of gold nanoparticles was confirmed from the characteristic surface plasmon absorption band at 522 nm and transmission electron microscopy revealed the average particle size to be ∼7 nm. Chloroquine was conjugated to thiolated gold nanoparticles by using EDC/NHS chemistry and the binding was analyzed using optical density measurement and Fourier transform infrared spectroscopy. The chloroquine–conjugated gold nanoparticles (GNP–Chl) were found to interact efficiently with BSA. Thermodynamic parameters suggest that the binding is driven by both enthalpy and entropy, accompanied with only a minor alteration in protein’s structure. Competitive drug binding assay revealed that the GNP–Chl bind at warfarin binding site I in subdomain IIA of BSA and was further supported by Trp212 fluorescence quenching measurements. Unraveling the nature of interactions of GNP–Chl with BSA would pave the way for the design of nanotherapeutic agents with improved functionality, enriching the field of nanomedicine.

Relationship of thyroid function with body mass index and insulin-resistance in euthyroid obese subjects

It is recognized that overt thyroid dysfunction is associated with weight changes, but the influence of a minor alteration of thyroid function remains unclear. This study aimed to further investigate the relationship between obesity and thyroid function and to examine the possible role of insulin resistance on the hypothalamic-pituitary- thyroid axis. Serum TSH and free T4 (FT4) levels, anthropometric and metabolic parameters were evaluated in 581 obese patients. In all patients TSH values progressively increased according to the severity of obesity and were positively correlated with body mass index (p=0.001, r=0.13) and waist circumference (p=0.02, r=0.11). Patients with insulin resistance showed higher TSH (1.8±1.0 vs 1.6±0.9 μUI/l; p=0.03) and lower FT4 levels (13.8±2.3 vs 15.0±2.2 pmol/l; p<0.001), as compared with patients with normal insulin sensitivity. Moreover, TSH was positively correlated with fasting insulin (p<0.001, r=0.152) and homeostasis model assessment of insulin resistance (HOMA-IR; p<0.001, r=0.148), and negatively correlated with Quantitative Insulin Sensitivity Check Index (QUICKI; p<0.001, r=-0.148); FT4 was negatively associated with fasting insulin (p<0.001, r=-0.287) and HOMA-IR (p<0.001, r=-0.295), and positively associated with QUICKI (p<0.001, r=0.295). A relationship between thyroid function and overweight/ obesity condition seems to exist, mainly influenced by insulin resistance. Whether variations in TSH and/or thyroid hormones, within a normal range, can influence body weight or whether obesity per se can alter thyroid function cannot be stated so far. Further studies are needed to assess the link between thyroid function and body weight, by considering not only changes in thyroid hormones, but also body fat distribution, obesity duration and low-grade inflammation.

Dental implant changes following incineration

Non-visual identification of victims utilizes DNA, fingerprint and dental comparison as primary scientific identifiers. In incidents where a victim has been incinerated, there may be loss of fingerprint detail and denaturing of DNA. Although extremely durable, tooth loss will also occur with extreme temperatures and the characteristics of recovered dental implants, if any, may be the only physical identifying data available. Currently, there are no experimental investigations to determine what changes occur to dental implants following high temperature exposure. A selection of dental implants was radiographed, utilizing purpose built apparatus to allow standard methodology. They were then heated in an INFI-TROL™ kiln to a maximum temperature of 1125 °C and the radiographic procedure repeated. Image subtraction evaluation of the radiographs was recorded using Adobe ® Photoshop ®. Both commercially pure titanium and titanium alloy dental implants survived the incineration and there was oxidation of the surface leading to minor alteration of the image. There was, however, no detectable sagging of the implants. The results of this research suggest that dental implants are still recognizable following incineration. In scenarios commonly seen by forensic odontologists, heat will destroy both teeth and conventional dental restorative materials. Implants, however, will resist these conditions and will also retain the features necessary to identify the type of implant.

Trimming Nanostructured Walls While Fluorinating their Surfaces: A Route to Making and Widening Pores of Nanoporous Materials and Efficient Catalysts

We report on the synthesis and characterization of highly ordered mesoporous fluorosilicas (OMFs) and nanoporous and corrugated fluorosilica nanospheres which contain 2.4−7.0 wt % F, corresponding to a loading of 1.3−3.7 mmol/g. Synthesis of these materials is carried out from parent mesoporous silicas (MCM-41 and SBA-15) and silica nanospheres under ambient conditions using dilute nonaqueous solutions of triethyloxonium tetrafluoroborate (Et3OBF4). As evidenced by nitrogen physisorption measurements, small angle powder X-ray diffraction (XRD), and transmission electron microscopy (TEM), fluorination of the mesostructures is accomplished with only minor alteration of the materials’ overall order. Detailed compositional analyses before and after fluorination are carried out with the aid of FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) as well as elemental analysis proving the existence of silicon oxyfluoride species. FTIR studies show the appearance of new absorptions (730−750 cm−1) upon fluorination corresponding to [F6−nSi(OH)n]2−, O4/2SiF species or Si−O−Si stretches altered by the presence of nearby Si−F species as well as general broadening of the Si−O−Si asymmetric stretching region (1000−1200 cm−1). XPS analyses exhibit two distinct F species observed at 690.5 and 687.6 eV corresponding to silicon oxyfluoride (SiOF) and silicon fluoride (SiF), respectively. Surface silanol content is evaluated by 29Si HP-MAS NMR spectroscopy, which shows significant reductions in (Q2+Q3)/Q4 ratios from 1.26, 0.61, and 1.07 to 0.22, 0.38, and 0.61 for SBA-15, trimethylsilyl-capped SBA-15, and MCM-41 mesoporous silicas, respectively, because of the formation of (SiO3)SiF or pentacoordinated (SiO4)SiF species. The as-described synthetic procedure is also applied to sulfonic acid (−SO3H)-functionalized SBA-15. Enhancement of the acid-catalyzed ring opening of styrene oxide by aniline to produce the corresponding β-aminoalcohol by the fluorinated materials is presented. Ring opening of styrene oxide by aniline at room temperature after 4 h using −SO3H functionalized SBA-15 result in 77% conversion, whereas the as-synthesized OMF and OMF-SO3H materials exhibit 79% and 87% conversions, respectively. Fluorination of silica nanospheres with Et3OBF4 under similar conditions also produces etched nanoporous fluorosilica nanospheres with different degrees of exfoliation depending on the fluorination temperature.

The role of kinetic effects, including plasma rotation and energetic particles, in resistive wall mode stability

The resistive wall mode (RWM) instability in high-beta tokamaks is stabilized by energy dissipation mechanisms that depend on plasma rotation and kinetic effects. Kinetic modification of ideal stability calculated with the “MISK” code [B. Hu et al., Phys. Plasmas 12, 057301 (2005)] is outlined. For an advanced scenario ITER [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)] plasma, the present calculation finds that alpha particles are required for RWM stability at presently expected levels of plasma rotation. Kinetic stabilization theory is tested in an experiment in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] that produced marginally stable plasmas with various energetic particle contents. Plasmas with the highest and lowest energetic particle content agree with calculations predicting that increased energetic particle pressure is stabilizing but does not alter the nonmonotonic dependence of stability on plasma rotation due to thermal particle resonances. Presently, the full MISK model, including thermal particles and an isotropic slowing-down distribution function for energetic particles, overpredicts stability in NSTX experiments. Minor alteration of either effect in the theory may yield agreement; several possibilities are discussed.

The influence of Ceratocystis polonica inoculation and methyl jasmonate application on terpene chemistry of Norway spruce, Picea abies

Constitutive and inducible terpene production is involved in conifer resistance against bark beetles and their associated fungi. In this study 72 Norway spruce ( Picea abies) were randomly assigned to methyl jasmonate (MJ) application, inoculation with the bluestain fungus Ceratocystis polonica, or no-treatment control. We investigated terpene levels in the stem bark of the trees before treatment, 30 days and one year after treatment using GC–MS and two-dimensional GC (2D-GC) with a chiral column, and monitored landing and attack rates of the spruce bark beetle, Ips typographus, on the trees by sticky traps and visual inspection. Thirty days after fungal inoculation the absolute amount and relative proportion of (+)-3-carene, sabinene, and terpinolene increased and (+)-α-pinene decreased. Spraying the stems with MJ tended to generally increase the concentration of most major terpenes with minor alteration to their relative proportions, but significant increases were only observed for (−)-β-pinene and (−)-limonene. Fungal inoculation significantly increased the enantiomeric ratio of (−)-α-pinene and (−)-limonene 1 month after treatment, whereas MJ only increased that of (−)-limonene. One year after treatment, both MJ and fungal inoculation increased the concentration of most terpenes relative to undisturbed control trees, with significant changes in (−)-β-pinene, (−)-β-phellandrene and some other compounds. Terpene levels did not change in untreated stem sections after treatment, and chemical induction by MJ and C. polonica thus seemed to be restricted to the treated stem section. The enantiomeric ratio of (−)-α-pinene was significantly higher and the relative proportions of (−)-limonene were significantly lower in trees that were attractive to bark beetles compared to unattractive trees. One month after fungal inoculation, the total amount of diterpenes was significantly higher in putative resistant trees with shorter lesion lengths than in putative susceptible trees with longer lesions. Thus, terpene composition in the stem bark may be related to resistance of Norway spruce against I. typographus and C. polonica.

Proteomic analysis of common bean seed with storage protein deficiency reveals up-regulation of sulfur-rich proteins and starch and raffinose metabolic enzymes, and down-regulation of the secretory pathway

A deficiency in major seed storage proteins is associated with a nearly two-fold increase in sulfur amino acid content in genetically related lines of common bean (Phaseolus vulgaris). Their mature seed proteome was compared by an approach combining label-free quantification by spectral counting, 2-DE, and analysis of selective extracts. Lack of phaseolin, phytohemagglutinin and arcelin was mainly compensated by increases in legumin, alpha-amylase inhibitors and mannose lectin FRIL. Along with legumin, albumin-2, defensin and albumin-1 were major contributors to the elevated sulfur amino acid content. Coordinate induction of granule-bound starch synthase I, starch synthase II-2 and starch branching enzyme were associated with minor alteration of starch composition, whereas increased levels of UDP-glucose 4-epimerase were correlated with a 30% increase in raffinose content. Induction of cell division cycle protein 48 and ubiquitin suggested enhanced ER-associated degradation. This was not associated with a classical unfolded protein response as the levels of ER HSC70-cognate binding protein were actually reduced in the mutant. Repression of rab1 GTPase was consistent with decreased traffic through the secretory pathway. Collectively, these results have implications for the nutritional quality of common bean, and provide information on the pleiotropic phenotype associated with storage protein deficiency in a dicotyledonous seed.

δ18O composition of conodont apatite indicates climatic cooling during the Middle Pridoli

Phosphatic microfossils, such as conodonts and fish microremains (dermal scales) from the upper Silurian (Pridoli) of Lithuania have been studied for their oxygen isotope composition. The conodont colour alteration index of the biogenic apatite did not exceed 1.5 reflecting only a minor thermal alteration. Conodont δ 18O apatite values range from 17.7 to 19.2‰ V-SMOW, with the average values around 18.3‰. Fossil apatite of fish exoskeleton microremains from the same samples have lower δ 18O apatite values ranging from 15.2 to 17.4‰ V-SMOW, with the average values around 16.3‰ V-SMOW. Palaeoseawater temperatures calculated from conodont apatite δ 18O range from 24.8–31.5 °C, those derived from fish δ 18O give approximately 10 °C higher temperatures ranging from 32.6 to 38.1 °C. The lower δ 18O apatite values of fish apatite and thus the unrealistic high palaeotemperatures are interpreted as a result of diagenetic alteration. A significant positive shift in conodont apatite δ 18O of + 1.1‰ at the boundary between the Vievis and Lapės formations is observed, coinciding with a major facies change. It is interpreted as a mid-Pridoli event within the O zarkodina eosteinhornensis Bizone, or the O zarkodina remscheidensis Biozone reflecting a major cooling event, which may have resulted in the formation of an ice sheet in high latitudes and a glacio-eustatic sea-level fall.

Crystal Structures of Trypanosoma brucei Sterol 14α-Demethylase and Implications for Selective Treatment of Human Infections

Sterol 14alpha-demethylase (14DM, the CYP51 family of cytochrome P450) is an essential enzyme in sterol biosynthesis in eukaryotes. It serves as a major drug target for fungal diseases and can potentially become a target for treatment of human infections with protozoa. Here we present 1.9 A resolution crystal structures of 14DM from the protozoan pathogen Trypanosoma brucei, ligand-free and complexed with a strong chemically selected inhibitor N-1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethyl)-4-(5-phenyl-1,3,4-oxadi-azol-2-yl)benzamide that we previously found to produce potent antiparasitic effects in Trypanosomatidae. This is the first structure of a eukaryotic microsomal 14DM that acts on sterol biosynthesis, and it differs profoundly from that of the water-soluble CYP51 family member from Mycobacterium tuberculosis, both in organization of the active site cavity and in the substrate access channel location. Inhibitor binding does not cause large scale conformational rearrangements, yet induces unanticipated local alterations in the active site, including formation of a hydrogen bond network that connects, via the inhibitor amide group fragment, two remote functionally essential protein segments and alters the heme environment. The inhibitor binding mode provides a possible explanation for both its functionally irreversible effect on the enzyme activity and its selectivity toward the 14DM from human pathogens versus the human 14DM ortholog. The structures shed new light on 14DM functional conservation and open an excellent opportunity for directed design of novel antiparasitic drugs.

Advanced structures for heat transfer studies on diaphragms

Suspended diaphragm devices were designed for heat transfer studies of the diaphragm material and optionally added thin films. The diaphragm embeds a thin-film heating resistor and two thin-film thermistors to measure temperature drops along a rectangular diaphragm section. Custom design of interconnection limbs and thin-film devices enables a nearly uniform lateral temperature distribution and minor alteration of the temperature field by the thermistors. The device dimensions allow the simultaneous determination of thermal conductivity λ and emissivity ε from a single temperature transient experiment. For the stratified SiO2/SiNx diaphragm, λ=0.938W/Km and ε=32.8% was deduced. Applied to a 130 nm Cr film embedded between the dielectric layers, λCr=12.26W/Km was obtained. The embedded chromium layer changes the observed emissivity to 44.3%.

Modeling experimental results of diffusion of alkaline solutions through a compacted bentonite barrier

The interaction between concrete/cement and swelling clay (bentonite) has been modeled in the context of engineered barrier systems for deep geological disposal of high-level radioactive waste. The geochemical transformations observed in laboratory diffusion experiments at 60 and 90 °C between bentonite and different high-pH solutions (K–Na–OH and Ca(OH) 2-saturated) were reconciled with the reactive transport code CrunchFlow. For K–Na–OH solutions (pH = 13.5 at 25 °C) partial dissolution of montmorillonite and precipitation of Mg-silicates (talc-like), hydrotalcite and brucite at the interface are predicted at 60 °C, while at 90 °C the alteration is wider. Alkaline cations diffused beyond the mineralogical alteration zone by means of exchange with Mg 2+ in the interlayer region of montmorillonite. Very slow reactivity and minor alteration of the clay are predicted in the Ca(OH) 2-bentonite system. The model is a reasonable description of the experiments but also demonstrates the difficulties in modeling processes operating at a small scale under a diffusive regime.

A lossless robust data hiding scheme

This paper presents a lossless robust data hiding scheme. The original cover image can be recovered without any distortion after the hidden data have been extracted if the stego-image remains intact, and on the other hand, the hidden data can still be extracted correctly if the stego-image goes through JPEG compression to some extent. The proposed scheme divides a cover image into a number of non-overlapping blocks and calculates the arithmetic difference of each block. Bits are embedded into blocks by shifting the arithmetic difference values. The shift quantity and shifting rule are fixed for all blocks, and reversibility is achieved. Furthermore, owing to the separation of bit-0-zone and bit-1-zone as well as the particularity of arithmetic difference, minor alteration applying to the stego-image generated by non-malicious attacks such as JPEG compression will not cause the bit-0-zone and the bit-1-zone to overlap, and robustness is achieved. Experimental results show that, compared with previous works, the performance of the proposed scheme is significantly improved.

The Millennium Uranium Deposit, Athabasca Basin, Saskatchewan, Canada: An Atypical Basement-Hosted Unconformity-Related Uranium Deposit

The Millennium uranium basement-hosted unconformity-related deposit is one of the most recent discoveries of basement-hosted deposits, and may hold as much as 46.8 million pounds (18,000 metric tonnes U) at an average grade of 4.53 percent U3O8. The alteration zone associated with the deposit is atypical, as it consists predominantly of muscovite rather than the chlorite and muscovite commonly found in the other basement-hosted deposits of the Athabasca basin. The preore stage consists of early minor clinochlore alteration at temperatures of about 275°C, interpreted to result from retrograde metamorphism of the basement rocks prior to the deposition of the Athabasca basin. This clinochlore event is followed by an extensive 1Mc muscovite alteration of the basement rocks by Na-K-Fe-rich basinal brines at temperatures of about 250°C, creating up to 25 percent void space in the basement rocks. Subsequently, a weak chamoisite alteration resulted from Fe-Mg-Ca-rich fluids with temperatures of about 300°C that evolved from reactions between the basinal brines and the basement rocks. Ore stage uraninite has an extrapolated chemical age of 1590 Ma and is contemporaneous with synore 1Mc muscovite and iron oxide deposited at temperatures near 250°C from fluids with similar δ 18O but lower δ D values to preore basinal fluids. The low δ D values indicate postdepositional exchange of H isotopes with Cenozoic fluids. Postore alteration consists of dravite and sudoite precipitated from Mg-Ca rich fluids, from the same evolved basinal brines that precipitated preore chamoisite, at temperatures of about 185°C, filling voids created during the preore stage. Our results indicate that the pre- and synore minerals were formed dominantly by basinal fluids, with no contribution from basement fluids, which differ from some other basement-hosted deposits in the Athabasca basin where basement-derived fluid influx was more significant. Several U-Pb and Ar-Ar resetting events recorded on preore muscovite and on uraninite are coincident with fluid flow induced by distal orogenies, remobilizing radiogenic Pb from the deposit. The radiogenic Pb remobilization events were not widespread as the presence of radiogenic Pb is restricted to basement rocks proximal to the deposit and along the unconformity.

The Effects of Tail Biopsy for Genotyping on Behavioral Responses to Nociceptive Stimuli

Removal of a small segment of tail at weaning is a common method used to obtain tissue for the isolation of genomic DNA to identify genetically modified mice. When genetically manipulated mice are used for pain research, this practice could result in confounding changes to the animals' responses to noxious stimuli. In this study, we sought to systematically investigate whether tail biopsy representative of that used in standard genotyping methods affects behavioral responses to a battery of tests of nociception. Wild-type littermate C57BL/6J and 129S6 female and male mice received either tail biopsies or control procedural handling at Day 21 after birth and were then tested at 6–9 weeks for mechanical and thermal sensitivity. C57BL/6J mice were also tested in the formalin model of inflammatory pain. In all tests performed (von Frey, Hargreaves, modified Randall Selitto, and formalin), C57BL/6J tail-biopsied animals' behavioral responses were not significantly different from control animals. In 129S6 animals, tail biopsy did not have a significant effect on behavioral responses in either sex to the von Frey and the modified Randall-Selitto tests of mechanical sensitivity. Interestingly, however, both sexes exhibited small but significant differences between tail biopsied and control responses to a radiant heat stimulus. These results indicate that tail biopsy for genotyping purposes has no effect on nocifensive behavioral responses of C57BL/6J mice, and in 129S6 mice, causes only a minor alteration in response to a radiant heat stimulus while other nocifensive behavioral responses are unchanged. The small effect seen is modality- and strain-specific.

Inhibition of rice bran lipase by azadirachtin from Azadirachta indica

AbstractBACKGROUND: Chemical constituents of the neem tree are extensively explored; the major component present in the tree is azadirachtin. Azadirachtin, a tetranortriterpenoid, is remarkable for its chemical complexity and for its biological activity. This study, for the first time, has provided information on the interaction and inhibition of rice bran lipase (RBL) by azadirachtin. RBL, an esterase, is a versatile enzyme that catalyzes the hydrolysis of ester linkages, primarily in neutral lipids such as triglycerides.RESULTS: The catalytic activity of RBL in the presence of azadirachtin has been investigated. There was a decrease in enzyme activity relative to the control at all concentrations tested. At 1 mmol L−1 concentration of azadirachtin the enzyme loses 84% of its activity. The kinetics of inhibition of RBL by azadirachtin are competitive in nature. From analysis of the kinetic data the inhibition constant Ki is found to be 0.14 mmol. Fluorescence measurements showed a gradual decrease in emission intensity; a red shift in emission maximum may be attributed to perturbation of the aromatic residues. Far‐ultraviolet circular dichroism results showed minor conformational changes.CONCLUSION: The results suggest that azadirachtin specifically inhibits and binds to RBL in bringing about inhibition with minor structural alteration. This inactivation of RBL by azadirachtin can be utilized to prevent oxidation of RBL with an ultimate goal of exploiting the potential of the plant source for producing edible‐grade oil from rice bran using a natural molecule at very low concentration. Copyright © 2009 Society of Chemical Industry

High primary productivity and nitrogen cycling after the Paleoproterozoic phosphogenic event in the Aravalli Supergroup, India

The causes of atmospheric oxygenation in the Paleoproterozoic are multifaceted yet poorly understood. An increase in the level of primary productivity however may have been an important factor in producing large amounts of oxygen in the atmosphere. A likely environmental consequence of atmospheric oxygenation is an increased abundance of seawater nitrate, which would have resulted in a fundamental change from the Archean nitrogen cycle. In this study, we investigate these questions using the carbon and nitrogen isotope compositions of carbonaceous shales from the Paleoproterozoic Aravalli Supergroup, India. The shales occur stratigraphically above one of the oldest phosphogenic events that took place around 2.0Ga. Shales in the phosphate domain of the Jhamarkotra Formation from the Lower Aravalli Group have distinct characteristics from coeval shales in the non-phosphate domain. Carbonaceous shales of the phosphate domain contain relatively high V and U/Th, typical of oxygen-deficient environments. These shales also have a high organic content of up to 14wt%, generally homogeneous δ13Corg values around −29‰, C/NWR up to 360 and a large range of δ15N values between −5 and +27‰. Their organic matter has low H/C and O/C and Raman spectra characteristic of lower greenschist to lower amphibolite facies metamorphism, which suggests a moderate alteration of geochemical compositions. Data from these shales also suggest high primary productivity under eutrophic conditions, as well as intense recycling of organic nitrogen through ammonium assimilation and denitrification at the time of sedimentation.In contrast, carbonaceous shales from the non-phosphate domain of the Jhamarkotra Formation contain trace element abundances characteristic of more oxygenated conditions. They contain less than 3wt% organic matter with δ13Corg values often between −13 and −18‰, whole-rock δ15N values between +5 and +12‰ and C/NWR below 56. Acid-insoluble organic matter from these shales has high H/C and O/C, and Raman spectral characteristics typical of lower greenschist facies metamorphism, which suggests only minor alteration of isotope compositions. Data gleaned from carbonaceous shales of the non-phosphate domain are interpreted to indicate high rates of primary productivity as well as the existence of a modern-like nitrogen cycle in this open-marine environment at the mouth of the Udaipur Epicontinental Sea. The interpretation of high primary productivity in carbonaceous shales from both domains of the Jhamarkotra Formation is consistent with stratigraphically underlying 13C-enriched carbonates and with their associated stromatolitic phosphorites. Therefore, increased fluxes of phosphorous in Paleoproterozoic seawater may have played an important role in stimulating increased levels of primary productivity and the rise of atmospheric oxygen.

Analysis of the geochemical variability in lepisosteid scales from the Fontllonga-3 site (early Danian, Tremp Formation, South Central Pyrenees, Spain): Implications for palaeoenvironmental studies

Rare Earth Element (REE), Ba/Ca, Sr/Ca and δ 18O PO4 analyses have been performed on the ganoine and isopedine of different types of isolated scales (anterior, middle, posterior flank scales and dorsal body margin scales) from juvenile lepisosteids from the Fontllonga-3 site (early Danian, Tremp Formation, South-Central Pyrenees, Spain) with the aim of detecting the most suitable kind of scale to be used in palaeoclimate studies. The REE flat-shape patterns obtained in lepisosteid scales from Fontllonga-3 are indicative of the absence of late stage diagenesis and recrystallization and have confirmed the identification of the palaeoenvironment where the Fontllonga-3 lepisosteids inhabited to be that of an estuary. The Ba/Ca palaeothermometer shows that posterior flank scales record on average 4.52 °C (ganoine) and 3.49 °C (isopedine) higher temperatures when compared to middle flank scales, which may be related to the fact that posterior flank scales grow preferentially during the warm season, whilst middle flank scales, which have the greatest number of layers of ganoine per unit of time and grow all year round, record a greater amplitude with respect to palaeoenvironmental and palaeoclimatic variations. Temperature values obtained from anterior flank scales follow a pattern similar to that showed by middle flank scales, whilst temperature values provided by dorsal scales resemble the pattern furnished by posterior flank scales. The same relationship between scale position and temperature but to a lesser degree (1.48 °C) is also evident in the calculated δ 18O PO4 temperatures. The Ba/Ca palaeothermometer was applied by considering Ba/Ca ratios of the water for different types of environments and it has been found out that a ratio similar to that of marine waters yielded the best approximation to δ 18O PO4 temperatures (29.82 ± 3.76 °C). The mean Ba/Ca temperature value obtained from the analysis of all the ganoine samples (26.96 ± 5.72 °C) is also consistent with the temperature of the water in which extant relatives of osteoglossiform fish, whose remains have been found in Fontllonga-3 along with lepisosteid remains, inhabit nowadays (24–40 °C, with mean values of 27 to 32 °C). The mean Ba/Ca temperature values furnished by the isopedine are lower than that obtained on the ganoine which may be due to minor diagenetic alteration. On account of these results, it is recommended that a distinction should be made between different types of scales as this could provide information concerning the summer growth temperature (posterior flank scales) as well as the annual temperature range (middle flank scales). Furthermore, it is recommended that ganoine be used in all studies as it appears to be the most resistant tissue in lepisosteid scales to diagenetic alteration.

Structural polymorphism of the four-repeat Oxytricha nova telomeric DNA sequences

G-quadruplexes are four-stranded nucleic acid complexes that exhibit a great deal of polymorphism. Recently a group described the polymorphism exhibited by the four-repeat of the Oxytricha nova telomeric sequences (Lee, J.Y., Yoon, J., Kihm, H.W., Kim, D.S., Biochemistry 2008, 47, 3389–3396). In this study we evaluated the effects of G-tract and loop lengths on this behaviour using circular dichroism (CD) and gel electrophoresis. The largest changes were detected for oligonucleotides with different numbers of consecutive G residues. Furthermore, decreasing the number of residues between the G runs, the loops, from four to three only results in minor alteration in the polymorphism. However, the shortening of the G-tract from four to three guanine residues led to characteristically anti-parallel G-quadruplex CD spectra. Finally, we show that adenine bases in the loop sequences are less likely to form G-quadruplexes in the presence of Na + cations than those comprised of thymine residues. The results presented here are an addition to the modest information available for predicting the type of G-quadruplex to be formed from G-rich sequences in aqueous solutions containing sodium or potassium ions.

Endothelium‐dependent contractions in SHR: a tale of prostanoid TP and IP receptors

In the aorta of spontaneously hypertensive rats (SHR), the endothelial dysfunction is due to the release of endothelium-derived contracting factors (EDCFs) that counteract the vasodilator effect of nitric oxide, with no or minor alteration of its production. The endothelium-dependent contractions elicited by acetylcholine (ACh) involve an increase in endothelial [Ca(2+)](i), the production of reactive oxygen species, the activation of endothelial cyclooxygenase-1, the diffusion of EDCF and the subsequent stimulation of smooth muscle cell TP receptors. The EDCFs released by ACh have been identified as PGH(2) and paradoxically prostacyclin. Prostacyclin generally acts as an endothelium-derived vasodilator, which, by stimulating IP receptors, produces hyperpolarization and relaxation of the smooth muscle and inhibits platelet aggregation. In the aorta of SHR and Wistar-Kyoto rats, prostacyclin is the principal metabolite of arachidonic acid released by ACh. However, in SHR aorta, prostacyclin does not produce relaxations but activates the TP receptors on vascular smooth muscle cells and produces contraction. The IP receptor is not functional in the aortic smooth muscle cells of SHR as early as 12 weeks of age, but its activity is not reduced in platelets. Therefore, prostacyclin in the rule protects the vascular wall, but in the SHR aorta it can contribute to endothelial dysfunction. Whether or not prostacyclin plays a detrimental role as an EDCF in other animal models or in human remains to be demonstrated. Nevertheless, because EDCFs converge to activate TP receptors, selective antagonists of this receptor, by preventing endothelium-dependent contractions, curtail the endothelial dysfunction in diseases such as hypertension and diabetes.

Fungal diversity and deterioration in mummified woods from the ad Astra Ice Cap region in the Canadian High Arctic

Non-permineralized or mummified ancient wood found within proglacial soil near the ad Astra Ice Cap (81°N, 76°W), Ellesmere Island, Canada was investigated to ascertain the identification of the trees, current morphological and chemical characteristics of the woods and the fungi within them. These woods, identified as Betula, Larix, Picea and Pinus, were found with varying states of physical and chemical degradation. Modern microbial decomposition caused by soft rot fungi was evident and rDNA sequencing of fungi obtained from the samples revealed several species including Cadophora sp., Exophiala sp., Phialocephala sp., as well as others. Analytical 13C-labeled tetramethylammonium hydroxide thermochemolysis showed the lignin from the ancient wood was in a high degree of preservation with minor side chain alteration and little to no demethylation or ring hydroxylation. The exposure of these ancient woods to the young soils, where woody debris is not usually prevalent, provides carbon and nutrients into the polar environment that are captured and utilized by unique decay fungi at this Arctic site.