Tree‐ring stable isotopes record the impact of a foliar fungal pathogen on CO2 assimilation and growth in Douglas‐fir

Swiss needle cast (SNC) is a fungal disease of Douglas‐fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree‐rings of Douglas‐fir and a non‐susceptible reference species (western hemlock, Tsuga heterophylla) to evaluate their use as proxies for variation in past SNC infection, particularly in relation to potential explanatory climate factors. We sampled trees from an Oregon site where a fungicide trial took place from 1996 to 2000, which enabled the comparison of stable isotope values between trees with and without disease. Carbon stable isotope discrimination (Δ¹³C) of treated Douglas‐fir tree‐rings was greater than that of untreated Douglas‐fir tree‐rings during the fungicide treatment period. Both annual growth and tree‐ring Δ¹³C increased with treatment such that treated Douglas‐fir had values similar to co‐occurring western hemlock during the treatment period. There was no difference in the tree‐ring oxygen stable isotope ratio between treated and untreated Douglas‐fir. Tree‐ring Δ¹³C of diseased Douglas‐fir was negatively correlated with relative humidity during the two previous summers, consistent with increased leaf colonization by SNC under high humidity conditions that leads to greater disease severity in following years.     

Increased ovarian follicular angiogenesis and dynamic changes of follicular vascular plexuses induced by equine chorionic gonadotropin in the gilt

Follicular angiogenesis and capillary degeneration are crucial ovarian processes in folliculogenesis. The present study was conducted to assess the changes in population of follicular vascular plexuses with different capillary status in prepubertal gilts 72 h after equine chorionic gonadotropin (eCG) (1,250 IU) treatment, using combined vascular corrosion casting and scanning electron microscopy. Follicular fluid concentrations of estradiol, progesterone and vascular endothelial growth factor (VEGF) were determined to confirm the follicular status. Based on the proliferative or degenerative characteristics of their capillaries, follicles were classified into three categories: active angiogenesis, low angiogenesis and degeneration. Irrespective of exogenous gonadotropin treatment in vivo, small follicular vascular plexuses (<4 mm in diameter) exhibited all three conditions in casted ovaries, while medium (4–5 mm) and large (>5 mm) plexuses showed only active angiogenesis or degeneration. eCG treatment significantly increased the population of large, but decreased that of small follicular plexuses. Most large follicular vascular plexuses showed active angiogenesis with higher follicular fluid estradiol:progesterone ratios and VEGF concentration. eCG also increased the percentage of medium follicular plexuses with active angiogenesis. The populations of small follicular plexuses with active angiogenesis were higher in controls, but decreased after eCG treatment. However, treatment of gilts with the gonadotropin increased the percentage of small plexuses (<1.0 mm) with low angiogenesis and those (1–3.9 mm) with extensive capillary degeneration. These findings are consistent with the hypothesis that angiogenesis is involved in selection and growth of small follicles in gilts under the regulation of gonadotropin.This work was supported by grants from the Program for Promotion of Basic Research Activities for Innovative Biosciences and Research for the Future Program, the Japan Society for the Promotion of Science (JSPS-RFTF97L00904) and the Canadian Institutes of Health Research (MOP-15691). J.Y.J. is a recipient of a CIHR-STIRRHS Postdoctoral Fellowship. A preliminary report of this work was presented at the 49th Annual Meeting of the Canadian Fertility and Andrology Society, 5–8 November 2003, Victoria, British Columbia, Canada     

Metabolic dynamics of Desulfovibrio vulgaris biofilm grown on a steel surface

In this study, a comparative metabolomics approach combining gas chromatography–mass spectrometry (GC-MS) and liquid chromatography–mass spectrometry (LC-MS) was applied first between planktonic cells and biofilms and then between pure cultures and biofilms of Desulfovibrio vulgaris. The results revealed that the overall metabolic level of the biofilm cells was down-regulated, especially for metabolites related to the central carbon metabolism, compared to the planktonic cells and the pure culture of D. vulgaris. In addition, pathway enrichment analysis of the 58 metabolites identified by GC-MS showed that fatty acid biosynthesis in the biofilm cells was up-regulated, suggesting that fatty acids may be important for the formation, maintenance and function of D. vulgaris biofilm. This study offers a valuable perspective on the metabolic dynamics of the D. vulgaris biofilm.     

Evaluation and optimization of nucleic acid extraction methods for the molecular analysis of bacterial communities associated with corroded carbon steel

Different DNA and RNA extraction approaches were evaluated and protocols optimized on in situ corrosion products from carbon steel in marine environments. Protocols adapted from the PowerSoil DNA/RNA Isolation methods resulted in the best nucleic acid (NA) extraction performances (ie combining high NA yield, quality, purity, representativeness of microbial community and processing time efficiency). The PowerSoil RNA Isolation Kit was the only method which resulted in amplifiable RNA of good quality (ie intact 16S/23S rRNA). Sample homogenization and hot chemical (SDS) cell lysis combined with mechanical (bead-beating) lysis in presence of a DNA competitor (skim milk) contributed to improving substantially (around 23 times) the DNA yield of the PowerSoil DNA Isolation Kit. Apart from presenting NA extraction strategies for optimizing extraction parameters with corrosion samples from carbon steel, this study proposes DNA and RNA extraction procedures suited for comparative molecular analysis of total and active fractions of bacterial communities associated with carbon steel corrosion events, thereby contributing to improved MIC diagnosis and control.     

The effect of long-term nitrate treatment on SRB activity,corrosion rate and bacterial community composition in offshore water injection systems

Biogenic production of hydrogen sulphide (H₂S) is a problem for the oil industry as it leads to corrosion and reservoir souring. Continuous injection of a low nitrate concentration (0.25–0.33 mM) replaced glutaraldehyde as corrosion and souring control at the Veslefrikk and Gullfaks oil field (North Sea) in 1999. The response to nitrate treatment was a rapid reduction in number and activity of sulphate-reducing bacteria (SRB) in the water injection system biofilm at both fields. The present long-term study shows that SRB activity has remained low at ≤0.3 and ≤0.9 μg H₂S/cm²/day at Veslefrikk and Gullfaks respectively, during the 7–8 years with continuous nitrate injection. At Veslefrikk, 16S rRNA gene based community analysis by PCR–DGGE showed that bacteria affiliated to nitrate-reducing sulphide-oxidizing Sulfurimonas (NR–SOB) formed major populations at the injection well head throughout the treatment period. Downstream of deaerator the presence of Sulfurimonas like bacteria was less pronounced, and were no longer observed 40 months into the treatment period. The biofilm community during nitrate treatment was highly diverse and relative stable for long periods of time. At the Gullfaks field, a reduction in corrosion of up to 40% was observed after switch to nitrate treatment. The present study show that nitrate injection may provide a stable long-term inhibition of SRB in sea water injection systems, and that corrosion may be significantly reduced when compared to traditional biocide treatment.     

Self‐Assembled 2D Perovskite Layers for Efficient Printable Solar Cells

2D organic–inorganic hybrid Ruddlesden–Popper perovskites have emerged recently as candidates for the light‐absorbing layer in solar cell technology due largely to their impressive operational stability compared with their 3D‐perovskite counterparts. The methods reported to date for the preparation of efficient 2D perovksite layers for solar cells involve a nonscalable spin‐coating step. In this work, a facile, spin‐coating‐free, directly scalable drop‐cast method is reported for depositing precursor solutions that self‐assemble into highly oriented, uniform 2D‐perovskite films in air, yielding perovskite solar cells with power conversion efficiencies (PCE) of up to 14.9% (certified PCE of 14.33% ± 0.34 at 0.078 cm²). This is the highest PCE to date for a solar cell with 2D‐perovskite layers fabricated by nonspin‐coating method. The PCEs of the cells display no evidence of degradation after storage in a nitrogen glovebox for more than 5 months. 2D‐perovskite layer deposition using a slot‐die process is also investigated for the first time. Perovskite solar cells fabricated using batch slot‐die coating on a glass substrate or R2R slot‐die coating on a flexible substrate produced PCEs of 12.5% and 8.0%, respectively.     

A study by scanning (SEM) and transmission (TEM) electron microscopy of the glomerular capillaries in developing rat kidney

Summary Kidneys of 2 to 10 day-old rats of Wistar and Sprague-Dawley strains were fixed with glutaraldehyde by retrograde vascular perfusion and then prepared for observation in TEM and SEM. In addition methacrylate casts of differentiating glomerular capillaries were examined by SEM. Although the glomerular vascular pattern differs from one glomerulus to another, its differentiation proceeds according to the following general plan. First the glomerular capillary splits longitudinally, finally to form 3 to 5 lobules consisting of a capillary network, sustained centrally by the mesangium.In the present study the differentiation of glomerular capillaries is described in five successive arbitrarily selected stages. At Stage I a capillary loop penetrates between the lower limb and the middle segment of the S-shaped body, the rudimentary nephron. At Stage II the capillary undergoes a first subdivision, establishing the primitive lobulation of the glomerulus. At Stage III the vascular and urinary poles differentiate. At Stage IV the glomerulus assumes the aspect of a spherical body, and the capillaries in each lobule undergo subdivision. In Stage V the glomerular vascular pattern approaches its adult appearance, although the maturation processes continue for an extended period of time. Hence in the 10 day-old rat the best-differentiated glomeruli are half the size of adult glomeruli, and their capillary loops are proportionally less well-developed. The capillaries of adjacent lobules may communicate with each other, but a direct vascular shunt between the afferent and efferent vessels cannot be demonstrated.Presented in part at the 60ème Congrés de l'Association des Anatomistes in Nice (27–30 May 1976) and the 73. Versammlung der Anatomischen Gesellschaft in Innsbruck (12–15 September 1978)The author thanks Miss Morena Ghisletta for excellent technical assistance     

Influence of pH,temperature, and concentration on stabilization of aqueous hornet silk solution and fabrication of salt‐free materials

We found that an aqueous solution of silk from cocoons produced by hornet larvae (hornet silk) can be obtained when the solution is adjusted to basic conditions of pH > 9.2. It is known that native hornet cocoons can be dissolved in concentrated aqueous solution of salts, such as lithium bromide (LiBr) and calcium chloride (CaCl₂). Upon the removal of these salts from solution by dialysis, solidification, gelation, or sedimentation of hornet silk is known to occur. In the present study, under basic conditions, however, no such solidification occurred, even after salt removal. In this study, ammonia was used for alkalization of solution because it is volatilized during the casting process and pure hornet silk materials can be obtained after drying. The effects of the concentrations of hornet silk and ammonia, as well as dialysis temperature, on preventing gelation during dialysis were investigated. Dialysis conditions that limit the degradation of hornet silk by hydrolysis in alkali solution were identified. Moreover, casting conditions to prepare flexible and transparent hornet silk film from aqueous ammonia solution were optimized. Molecular structural analysis of hornet silk in aqueous ammonia solution and cast film indicated the formation of α‐helix conformations. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 41–52, 2015.     

Thymic vascular system of the European common frog,Rana temporaria: a scanning electron-microscopic study of vascular casts

Vascular corrosion casts of the thymus of adult individuals of the European common frog, Rana temporaria, were analysed by scanning electron microscopy. The main arterial vessel, which is derived either from the temporal artery or from the auricular ramus, approaches the central territory of the gland and branches into twigs that, on penetrating the parenchyma, give rise to capillaries. Most of these capillaries run vertically towards the surface of the gland; they either join the superficial capillary plexus or follow this plexus for a variable distance and then run back towards the medulla, forming capillary loops. The former capillaries link with the extensive venous plexus composed of irregular meshes, whereas the latter capillaries join the venules at the cortico-medullary boundary and finally escape into collecting veins on the gland surface. The venous twigs, which join together near the gland, form the main thymic vein, which empties into the external jugular vein. The details of the thymic vasculature of the anuran amphibian, R. temporaria, are compared with those described in mammalian species, viz. the mouse, rat and guinea pig.     

Vascularization of the pars distalis of the hypophysis in the toad,Bufo bufo (L.) (Amphibia,Anura)

Summary The vascularization of the pars distalis of the hypophysis of the toad, Bufo bufo (L.), was studied by the traditional method of injecting a mixture of India-ink and gelatine into the circulatory system of the head via the arteria carotis communis. Further, methyl-methacrylate corrosion casts of the brains were made; the hypothalamo-adenohypophysial region of these corrosion casts was studied with the scanning electron microscope. The results showed that the portal vessels which arise from the median eminence do not supply distinct areas in the pars distalis as is supposed by the point-to-point-hypothesis. The portal vessels enter the ventro-median region of the pars distalis and branch off into a three-dimensional network of the secondary capillary plexus of the pars distalis. The plexus is made up mostly by four- to six-sided meshes. This angioarchitecture guarantees an optimal supply of the glandular cells of the pars distalis with nutritional factors and releasing hormones, on the one hand, and facilitates the removal of the hormones which are released by these cells, on the other hand. The venous drainage of the pars distalis is exerted mainly by two large veins, which bilaterally leave the dorso-lateral region (venous pole) of the pars distalis and by a few small veins, which drain into the wide, sinus-like vessel, which curves around the dorso-caudal region of the pars distalis and joins bilaterally the vena hypophysea transversa.This work was supported by the Fonds zur Förderung der wissenschaftlichen Forschung (Projekt Nr. 2183/N 39) and by the Stiftungs- und Förderungsgesellschaft der Paris-Lodron-Universität SalzburgThe authors wish to thank Mag. Ursula Albrecht for excellent technical assistance and Mr. Gerhard Sulzer for photographic work