Reactions of Purine Nucleosides with Aqueous Alkalies: The Effect of the C6 Substituent on the Kinetics of the Multistage Pathway

Abstract

Kinetics of the reactions of 6-substituted 9-(β-Q-ribofuranosyl)purines with aqueous alkalies have been studied liquid chromatographicaIly.     

The importance of hunting pressure, habitat preference and life history for population trends of breeding waterbirds in Finland

Populations of migratory species have undergone dramatic changes in recent decades, but little is known about the factors actually driving those changes. Of particular concern are quarry species such as migratory ducks (Anatidae), many of which have an unfavourable conservation status in Europe. By including both quarry and non-quarry species, as well as habitat preference and life history characteristics of the species, we investigated the relative importance of hunting pressure, both in Finland and at the European level, in explaining population changes of 16 species of migratory waterbirds in Finland during 1986–2011. Ban of lead shot in 1996 resulted in considerably lower annual hunting bags in Finland thereafter. Species which had the highest hunting pressure had the most negative slopes in population trends from 1986 up to 1997, suggesting that hunting probably limited those populations. However, in general population trends of the species were not strongly associated with hunting pressure in Finland or in Europe. Nor were basic life history characteristics (body mass and clutch size) associated with population trends of the species. In contrast, recent population declines were associated with habitat preferences of the species: those breeding mainly in eutrophic lakes had more negative population trends than those breeding in oligotrophic lakes or generalist species. Reasons for the relatively poor status of species preferring eutrophic lakes probably include over-eutrophication of nutrient-rich lakes, resulting in less abundant food resources, and increased nest depredation.     

New separation-free assay technique for SNPs using two-photon excitation fluorometry

A new separation-free method for detection of single nucleotide polymorphisms (SNPs) is described. The method is based on the single base extension principle, fluorescently labeled dideoxy nucleotides and two-photon fluorescence excitation technology, known as ArcDia™ TPX technology. In this assay technique, template-directed single base extension is carried out for primers which have been immobilized on polymer microparticles. Depending on the sequence of the template DNA, the primers are extended either with a labeled or with a non-labeled nucleotide. The genotype of the sample is determined on the basis of two-photon excited fluorescence of individual microparticles. The effect of various assay condition parameters on the performance of the assay method is studied. The performance of the new assay method is demonstrated by genotyping the SNPs of human individuals using double-stranded PCR amplicons as samples. The results show that the new SNP assay method provides sensitivity and reliability comparable to the state-of-the-art SNaPshot™ assay method. Applicability of the new method in routine laboratory use is discussed with respect to alternative assay techniques.     

Quantitative detection of cell surface protein expression by time-resolved fluorimetry.

A method is introduced for quantitative detection of cell surface protein expression. The method is based on immunocytochemistry, the use of long decay time europium(III) chelate and platinum(II) porphyrin labels, and detection of photoluminescence emission from adhered cells by time-resolved fluorimetry. After immunocytochemistry, the assay wells are evaporated to dryness and measured in the dry state. This protocol allows repeated and postponed analysis and microscopy imaging. In order to investigate the performance of the method, we chose expression of intercellular adhesion molecule-1 (ICAM-1) of endothelial cell line EAhy926 as a research target. The expression of ICAM-1 on the cells was enhanced by introduction of a cytokine, tumour necrosis factor-alpha (TNFalpha). The method gave signal:background ratios (S:B) of 20 and 9 for europium and platinum labels, respectively, whereas prompt fluorescent FITC label gave a S:B of 3. Screening window coefficients (=Z'-factor) were >0.5 for all the three labels, thus indicating a score for an excellent screening assay. In conclusion, the method appears to be an appropriate choice for protein expression analysis, both in high-throughput screening applications, and for detailed sample investigation by fluorescent microscopy imaging.     

Polluted environment and cold weather induce laying gaps in great tit and pied flycatcher

We studied the occurrence of laying gaps in free-living populations of the pied flycatcher, Ficedula hypoleuca, and the great tit, Parus major, in a pollution gradient of a copper smelter in south-west Finland. Laying gaps were 2.8 times more common in F. hypoleuca than in P. major. The probability of laying gaps was highest in the heavily polluted zone and lowest in the unpolluted zone for both bird species. Cold weather at the time of laying increased the number of laying gaps in both species, but in P. major this effect was most pronounced in the heavily polluted environment. In the most heavily polluted environment the laying gaps were more likely to occur near the beginning of the laying sequence in both species. The laying gap probability increased with increasing laying date in P. major but not in F. hypoleuca. We suggest that the increased number of laying gaps in the polluted environment results from limited Ca availability and the interference of heavy metals with Ca metabolism in laying females.     

The effects of iron-containing superoxide dismutases on haemodynamic parameters in spontaneously hypertensive rats

The product of FeSOD activity is hydrogen peroxide (H2O2). Furthermore, FeSOD can modify the chemical versatility of NO into its redox-active forms: nitrosonium cation (NO+) and nitroxyl anion (NO-). All of these low molecular weight species are vasoactive and, in particular, NO- induces calcitonin gene-related peptide (CGRP) synthesis (known to be the most potent relaxation-promoting peptide). In this study the effects of bolus infusions of iron-containing superoxide dismutase (FeSOD) and of superoxide dismutase containing both iron and manganese (FeMnSOD) on the arterial blood pressure (MAP), the arterial blood pressure (CO) and the total vascular resistance (TVR) in spontaneously hypertensive (SH) rats were determined. Bolus infusion of FeSOD induced a biphasic response in the MAP (an initial increase was followed by a significant decrease). At the end of the experiment the MAP returned to its basal value. FeMnSOD (the enzymatically inactive form of FeSOD) had no effect on the MAP in these experiments. Bolus infusions of FeSOD and of FeMnSOD had no effect either on the both the CO or on the TVR in SH rats. Our results indicate that arterial relaxation changes mediated by NO- may be important for regulation of blood pressure in SH rats.     

A Simple and Efficient DNA Isolation Method for Salvia officinalis

We report an efficient, simple, and cost-effective protocol for the isolation of genomic DNA from an aromatic medicinal plant, common sage (Salvia officinalis L.). Our modification of the standard CTAB protocol includes two polyphenol adsorbents (PVP 10 and activated charcoal), high NaCl concentrations (4?M) for removing polysaccharides, and repeated Sevag treatment to remove proteins and other carbohydrate contaminants. The mean DNA yield obtained with our Protocol 2 was 330.6?μg DNA g^?1 of dry leaf tissue, and the absorbance ratios 260/280 and 260/230?nm averaged 1.909 and 1.894, respectively, revealing lack of contamination. PCR amplifications of one nuclear (26S rDNA) and one chloroplast (rps16-trnK) locus indicated that our DNA isolation protocol may be used in common sage and other aromatic and medicinal plants containing essential oil for molecular biologic and biotechnological studies and for population genetics, phylogeographic, and conservation surveys in which nuclear or chloroplast genomes would be studied in large numbers of individuals.     

Selection on laying date is connected to breeding density in the pied flycatcher

Timing of reproduction and clutch size are important determinants of breeding success, especially in seasonal environments. Several recent bird population studies have shown changes in breeding time and in natural selection on it. These changes have often been linked with climate change, but few studies have investigated how the traits or natural selection are actually connected with climatic factors. Furthermore, the effect of population density on selection has been rarely considered, despite the potential importance of density in demographic processes. We studied variation in natural selection on laying date and on clutch size in relation to measures of spring phenology and population density in a long-term study of pied flycatchers in SW Finland. The phenological stage of the environment at mean egg-laying did not affect the direction of selection on either laying date or on clutch size. There was, however, stronger selection for earlier laying date when the breeding density of the population was high, suggesting that early breeding is not necessarily beneficial as such, but that its importance is emphasized when high population density increases competition. In addition, early breeding was favoured when the pre-breeding period was cool, which may indicate an increased advantage for the fittest individuals in harsher conditions. In the middle of the twentieth century, there was selection for large clutch size, which subsequently ceased, along with an overall decrease in recruit production. Our results indicate that attention should be paid to demographic factors such as breeding density when studying natural selection and temporal changes in it.     

Combined UV and Liquid Scintillation Detection in HPLC. Formation and Depurination of Substitution Inert Pt(II) Complexes of Purine Nucleosides

Abstract

Combined UV- and liquid scintillation-HPLC has been applied to study the complexing of purine nucleosides with Pt(II)-diamine ions, and the effect of the complex formation on the acidic depurination.