The in vivo growth and development of micropropagated Elatior begonias (Begonia x hiemalis): I. Study on the effect of lighting and substrate

Micropropagation is an efficient way to produce pathogen-free Elatior begonias. However, certain problems arise when these plants are used in commercial pot plant production. The plants grow too luxuriantly, the root collars remain thin and flowering is delayed. To investigate the impact of the growing method, an experiment with different sources of supplementary light and different substrates was arranged in spring 1987. The following Elatior begonia cultivars were studied: ’Afrodite’, ’Afrodite Special’,'Afrodite Rosa’, ’Mandela’, ’Barbara’, ’Connie’, ’Marja’ and ’Sirene’. Four different lamp types were used: high pressure sodium lamps (Airam SNaKd 330 W), high-pressure mercury lamps (Airam HgLX 400W), high-pressure metal halide lamps (Philips HPI/T 375 W) and, as a control treatment, incandescent lamps of 100W. The plants were potted in B2-peat (Sphagnum peat with moderate fertilization and medium sieving grade), B2-peat (3 parts) plus perlite (1 part) or B2-peat (2 parts) plus perlite (2 parts). The plants lighted with SNaKd or HgLX lamps were the highest, the broadest and the first to reach anthesis and the sale stage. The plants in the control group were the smallest and the last to reach anthesis and the sale stage. The effect of the substrate on the time required to reach anthesis and the sale stage was clear only in the cultivar ’Afrodite Special’; when potted in peat-perlite 2 + 2, its plants flowered 2 weeks later than in other substrate mixtures. The height and the width of the plants were not greatly affected by the substrate. None of the lamp types or substrates clearly increased the number of flower buds or the diameter of the root collar. The proportion of saleable plants varied with the cultivar, lighting and substrate. In most cultivars it was below 50 %. The chief factors reducing saleability were luxuriant growth, weak flowering and oblique growth habit

The effect of cytokinins in vitro on the growth and development of Elatior begonias (Begonia Elatior-hybr.)

Micropropagation involves the risk of somaclonal variation among the regenerated plants. It is possible that the components of the nutrient medium, especially growth substances, increase the frequency of variation. Elatior Begonia 'Barbara' plants were micropropagatedusing four cytokinins (zeatin 0.5—2.0 mg/l, kinetin 0.5—2.0 mg/l, IPA 0.5—2.0 mg/l or BAP 0.05—0.65 mg/l) in vitro. The number of shoots produced per explant and the subsequent quality of full-sized, flowering plants were studied. In general, the number of big (> 1 cm) and medium-sized (0.5 —1.0 cm) shoots decreased and the number of small

Transfer of elements into boreal forest ants at a former uranium mining site

Ants can influence ecological processes, such as the transfer of elements or radionuclides, in several ways. For example, they redistribute materials while foraging and maintaining their nests and have an important role in terrestrial food webs. Quantitative data of the transfer of elements into ants is needed, e.g., for developing improved radioecological models. In this study, samples of red wood ants (genus Formica), nest material, litter and soil were collected from a former uranium mining site in Eastern Finland. Concentrations of 33 elements were analyzed by Inductively Coupled Plasma-Mass Spectroscopy/Optical Emission Spectroscopy. Estimated element concentrations in spruce needles were used as a proxy for studying the transfer of elements into ants via aphids because spruces host the most important aphid farms in boreal forests. Empirically determined organism/medium concentration ratios (CRs) are commonly used in radioecological models. Ant/soil CRs were calculated and the validity of the fundamental assumption behind the of use of CRs (linear transfer) was evaluated. Elements that accumulated in ants in comparison to other compartments were cadmium, potassium, phosphorus, sulfur, and zinc. Ant uranium concentrations were low in comparison to soil, litter, or nest material but slightly elevated in comparison to spruce needles. Ant element concentrations were quite constant regardless of the soil concentrations. Non-linear transfer models could therefore describe the soil-to-ant transfer better than conventional CRs.</p

Transfer of elements relevant to radioactive waste into chironomids and fish in boreal freshwater bodies

Information on transfer of elements and their radionuclides is essential for radioecological modeling. In the present study, we investigated the transfer of Cl, Co, Mo, Ni, Se, Sr, U and Zn in a boreal freshwater food chain. These elements were selected on the basis that they have important radionuclides that might be released into the biosphere from various stages of the nuclear fuel cycle. Water, sediment, chironomid larvae (Chironomus sp.), roach (Rutilus rutilus) and perch (Perca fluviatilis) were sampled from two ponds near a former uranium mine and one reference pond located further away from the mining area. Concentrations measured in water, sediment and the three animal species indicated the importance of sediment as a source of uptake for most of the elements (but not Cl). This should be considered in radioecological models, which conventionally predict concentration in aquatic organisms from concentration in water. The results also show that the assumption of linear transfer (constant concentration ratio) may not be valid for elements into fish. The results of this study show that further basic research is needed to understand the fundamental processes involved in transfer of elements into freshwater organisms in order to develop radioecological models.</div

International study of childhood leukemia in residences near electrical transformer rooms.

OBJECTIVES New epidemiologic approaches are needed to reduce the scientific uncertainty surrounding the association between extremely low frequency magnetic fields (ELF-MF) and childhood leukemia. While most previous studies focused on power lines, the Transformer Exposure study sought to assess this association using a multi-country study of children who had lived in buildings with built-in electrical transformers. ELF-MF in apartments above built-in transformers can be 5 times higher than in other apartments in the same building. This novel study design aimed to maximize the inclusion of highly exposed children while minimising the potential for selection bias. METHODS We assessed associations between residential proximity to transformers and risk of childhood leukemia using registry based matched case-control data collected in five countries. Exposure was based on the location of the subject's apartment relative to the transformer, coded as high (above or adjacent to transformer), intermediate (same floor as apartments in high category), or unexposed (other apartments). Relative risk (RR) for childhood leukemia was estimated using conditional logistic and mixed logistic regression with a random effect for case-control set. RESULTS Data pooling across countries yielded 16 intermediate and 3 highly exposed cases. RRs were 1.0 (95% CI: 0.5, 1.9) for intermediate and 1.1 (95% CI: 0.3, 3.8) for high exposure in the conditional logistic model. In the mixed logistic model, RRs were 1.4 (95% CI: 0.8, 2.5) for intermediate and 1.3 (95% CI: 0.4, 4.4) for high. Data of the most influential country showed RRs of 1.1 (95% CI: 0.5, 2.4) and 1.7 (95% CI: 0.4, 7.2) for intermediate (8 cases) and high (2 cases) exposure. DISCUSSION Overall, evidence for an elevated risk was weak. However, small numbers and wide confidence intervals preclude strong conclusions and a risk of the magnitude observed in power line studies cannot be excluded

Noninvasive and Quantitative Monitoring of the Distributions and Kinetics of MicroRNA-Targeting Molecules in Vivo by Positron Emission Tomography

MicroRNAs (miRNAs) are endogenous, small, noncoding ribonucleic acids (RNAs) that bind to the 3' untranslated regions of messenger RNAs (mRNAs) and induce translational repression or mRNA degradation. Although numerous studies have reported that miRNAs are of potential use for disease diagnostics and gene therapy, little is known about their fates in vivo. This study elucidated the whole-body distributions and kinetics of intravenously administered miRNA-targeting molecules in vivo by positron emission tomography (PET) imaging. A 22-mer sequence targeting miR-1513 was conjugated with three different chelators and labeled with gallium-68 (Ga-68). These tracers were compared with a scrambled 22-mer sequence; 22-mer with two single base substitutions; anti-miR-34 22-mer; hexathymidylate (T-6), a 6-mer sequence; and an unconjugated chelator. miR-15b was chosen as a target because it is important for bone remodeling. All three Ga-68-labeled anti-miR-15b molecules had similar biodistributions and kinetics, and they all accumulated in the bones, kidneys, and liver. The bone accumulation of these tracers was the highest in the epiphyses of long tubular bones, maxilla, and mandible. By contrast, the scrambled 22-mer sequence, the 6-mer, and the unconjugated chelator did not accumulate in bones. PET imaging successfully elucidated the distributions and kinetics of Ga-68-labeled chelated miRNA-targeting molecules in vivo. This approach is potentially useful to evaluate new miRNA-based drugs

Controlled Monofunctionalization of Molecular Spherical Nucleic Acids on a Buckminster Fullerene Core

An azide-functionalized 12-armed Buckminster fullerene has been monosubstituted in organic media with a substoichiometric amount of cyclooctyne-modified oligonucleo-tides. Exposing the intermediate products then to the same reaction (i. e., strain-promoted alkyne-azide cycloaddition, SPAAC) with an excess of slightly different oligonucleotide constituents in an aqueous medium yields molecularly defined monofunctionalized spherical nucleic acids (SNAs). This procedure offers a controlled synthesis scheme in which one oligonucleotide arm can be functionalized with labels or other conjugate groups (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, DOTA, and Alexa-488 demonstrated), whereas the rest of the 11 arms can be left unmodified or modified by other conjugate groups in order to decorate the SNAs' outer sphere. Extra attention has been paid to the homogeneity and authenticity of the C60-azide scaffold used for the assembly of full-armed SNAs