Adsorption of HSA, IgG and laminin-1 on model hydroxyapatite surfaces--effects of surface characteristics

Ellipsometry and mechanically assisted sodium dodecyl sulphate elution was utilized to study the adsorption of human serum albumin (HSA), human immunoglobulin G (IgG), and laminin-1, as well as competitive adsorption from a mixture of these proteins on spin-coated and sintered hydroxyapatite (HA) surfaces, respectively. The HA surfaces were characterized with respect to wettability and roughness by means of water contact angles and atomic force microscopy, respectively. Both surface types were hydrophilic, and the average roughness (Sa) and surface enlargement (Sdr) were lower for the sintered compared to the spin-coated HA surfaces. The adsorbed amounts on the sintered HA increased as follows: HSA < laminin-1 < IgG < the protein mixture. For the competitive adsorption experiments, the adsorbed fractions increased accordingly: HSA < laminin-1 < IgG on both types of HA substratum. However, a higher relative amount of HSA and laminin-1 and a lower relative amount of IgG was found on the spin-coated surfaces compared to the sintered surfaces. The effects observed could be ascribed to differences in surface roughness and chemical composition between the two types of HA substratum, and could have an influence on selection of future implant surface coatings.     

Validation of a modified fluorimetric assay for the screening of trichomonacidal drugs

A fluorimetric microassay that uses a redox dye to determine the viability of the flagellate Trichomonas vaginalis has been optimised to provide a more sensitive method to evaluate potential trichomonacidal compounds. Resazurin has been used in recent years to test drugs against different parasites, including trichomonadid protozoa; however, the reproducibility of these resazurin-based methods in our laboratory has been limited because the flagellate culture medium spontaneously reduces the resazurin. The objective of this work was to refine the fluorimetric microassay method previously developed by other research groups to reduce the fluorescence background generated by the media and increase the sensitivity of the screening assay. The experimental conditions, time of incubation, resazurin concentration and media used in the microtitre plates were adjusted. Different drug sensitivity studies against T. vaginalis were developed using the 5-nitroimidazole reference drugs, new 5-nitroindazolinones and 5-nitroindazole synthetic derivatives. Haemocytometer count results were compared with the resazurin assay using a 10% solution of 3 mM resazurin dissolved in phosphate buffered saline with glucose (1 mg/mL). The fluorimetric assay and the haemocytometer counts resulted in similar percentages of trichomonacidal activity in all the experiments, demonstrating that the fluorimetric microtitre assay has the necessary accuracy for high-throughput screening of new drugs against T. vaginalis.     

Connection between rod bivalents and incomplete meiotic association at NORs in Hordeum marinum Huds

The hypothesis of a connection between rod bivalent formation and incomplete meiotic association at NORs of SAT-chromosomes of H. marinum is supported. PMCs of H. marinum ssp. gussoneanum (2x), two diploid ssp. marinum × ssp. gussoneanum (2x) hybrids and two ssp. gussoneanum (4x) × Secale cereale hybrids at metaphase I (M-I) were analyzed by in situ hybridization. The probe pTa71 labelled rDNA sites at NORs of a single pair of homologous or near-homologous SAT-chromosomes of H. marinum in each material. In the three diploids, M-I was regular with ring bivalents and one or a few rods (av.13.52 bound arms cell(-1) ). More rod bivalents than the expected one out of seven, i.e. 30, 67 and 89% included rDNA-carrying chromosomes. Corresponding bound short arm frequencies were 0.89, 0.72 and 0.52, while long arms and arms of other chromosomes presented complete or near- complete association. The two heterogenomic hybrids had a less regular M-I (av. 8.04 bound arms cell(-1) ) including 20% rDNA-carrying rods with bound arm frequencies of 0.29 in short and 0.87 in long arms. Positions of chromosome associations were established in all 150 rDNA-carrying bivalents. In 77 bivalents with short arm associations, 4% of these occurred proximally to, none at, and 96% distally to rDNA sites, i.e. in satellites. In 143 bivalents with long arm associations, 83% occurred at interstitial and 17% at terminal positions. The observations combine increased frequency of rDNA-carrying rods with decreased frequency of association at NOR regions of SAT-chromosomes. The basis for the relationship is discussed.     

Disentangling the paradox of insect phenology: are temporal trends reflecting the response to warming?

The strength and direction of phenological responses to changes in climate have been shown to vary significantly both among species and among populations of a species, with the overall patterns not fully resolved. Here, we studied the temporal and spatial variability associated with the response of several insect species to recent global warming. We use hierarchical models within a model comparison framework to analyze phenological data gathered over 40 years by the Japan Meteorological Agency on the emergence dates of 14 insect species at sites across Japan. Contrary to what has been predicted with global warming, temporal trends of annual emergence showed a later emergence day for some species and sites over time, even though temperatures are warming. However, when emergence data were analyzed as a function of temperature and precipitation, the overall response pointed out an earlier emergence day with warmer conditions. The apparent contradiction between the response to temperature and trends over time indicates that other factors, such as declining populations, may be affecting the date phenological events are being recorded. Overall, the responses by insects were weaker than those found for plants in previous work over the same time period in these ecosystems, suggesting the potential for ecological mismatches with deleterious effects for both suites of species. And although temperature may be the major driver of species phenology, we should be cautious when analyzing phenological datasets as many other factors may also be contributing to the variability in phenology.     

Forecasting phenology: from species variability to community patterns

Shifts in species' phenology in response to climate change have wide-ranging consequences for ecological systems. However, significant variability in species' responses, together with limited data, frustrates efforts to forecast the consequences of ongoing phenological changes. Herein, we use a case study of three North American plant communities to explore the implications of variability across levels of organisation (within and among species, and among communities) for forecasting responses to climate change. We show how despite significant variation among species in sensitivities to climate, comparable patterns emerge at the community level once regional climate drivers are accounted for. However, communities differ with respect to projected patterns of divergence and overlap among their species' phenological distributions in response to climate change. These analyses and a review of hypotheses suggest how explicit consideration of spatial scale and levels of biological organisation may help to understand and forecast phenological responses to climate change.     

KCNE3 mutation V17M identified in a patient with lone atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac rhythm disorder with a lifetime risk for development of 25% for people aged 40 or older. In this study we aim for the functional assessment of a mutation in KCNE3 identified in a proband with early-onset lone AF. METHODS: Screening of genomic DNA from the proband led to identification of a KCNE3 V17M missense mutation. We heterologously expressed the accessory channel subunit in Xenopus laevis oocytes together with its known interacting potassium channel alpha-subunits. Further, we applied RT-PCR on human total RNA from left and right atria and ventricle. RESULTS: Electrophysiological recordings revealed an increased activity of Kv4.3/KCNE3 and Kv11.1/KCNE3 generated currents by the mutation, thereby conferring susceptibility of mutation carriers to faster cardiac action potential repolarization and thus vulnerability to re-entrant wavelets in the atria and thereby AF. CONCLUSION: Here we report a novel mutation in KCNE3 identified in a proband with early-onset lone AF possibly leading to gain-of-function of several cardiac currents. We suggest abnormalities in the KCNE3 gene as a potential genetic risk factor for initiation and/or maintenance of AF.