Variation for winter hardiness generated by androgenesis from
Festuca pratensis × Lolium multiflorum amphidiploid cultivars with different winter susceptibility
Androgenic populations produced from three Festuca pratensis × Lolium multiflorum amphidiploid (2n = 4x = 28) cultivars show wide within population variation for winter hardiness. Populations comprising a total of 423 androgenic plants derived from 23 donor plants from 3 Polish F. pratensis × L. multiflorum cultivars Felopa, Sulino, and Rakopan were studied over 3 years (1999–2002) in a field experiment at Lopuszna, Poland (20∘08′E, 49∘28′N, altitude 568 m). The results indicate that despite differences in winter hardiness between the three amphidiploid cultivars, the mean winter hardiness of androgenic progeny from each cultivar was the same. Thus an androgenesis component in a plant breeding programme may provide an opportunity to recover winter hardy genotypes from high yielding cultivars that are themselves adapted poorly to stress conditions. Androgenesis also evoked variation in snow mould resistance. In this case, androgenic plants with the greatest snow mould resistance were recovered from the least winter hardy donor cultivars and plants. The results indicated the low importance of snow mould resistance as a component of winter hardiness under the field conditions used for these experiments.
All-Male Asexuality: Origin and Maintenance of Androgenesis in the Asian Clam Corbicula
Abstract Androgenesis is a rare form of asexual male reproduction found in disparate taxa across the Tree of Life. Phylogenetic analyses of mitochondrial genes suggest that androgenesis has arisen repeatedly in the Asian clam genus Corbicula. Two of these androgenetic species have been introduced to North America. Multiple lines of genetic evidence suggest that although nuclear recombination between these two species is rare, mitochondrial genome capture is a frequent consequence of androgenetic parasitism of heterospecific eggs. Egg parasitism may also rarely result in partial nuclear genome capture between closely related species of Corbicula, which provides a mechanism for the otherwise clonal species to avoid the deleterious effects of asexuality. Egg parasitism among congeners may explain why androgenesis has been maintained in Corbicula after fixation and has not yet led to population extinction. This mechanism also provides an explanation for the apparent multiple origins of androgenesis in Corbicula as seen on the mitochondrial DNA phylogeny. We suggest that a single androgenetic lineage may have repeatedly captured mitochondrial genomes (as well as portions of nuclear genomes) from various sexual species, resulting in several distinct androgenetic species with distantly related mtDNA genomes and divergent morphologies.
Effective adsorption of lead ions using fly ash obtained in the novel circulating fluidized bed combustion technology
Abstract Fly ash was examined for the separation efficiency of Pb2+ ions from water in batch experiments. Fly ash is industrial waste produced from the incineration of sewage sludge by the novel circulating fluidized bed combustion (CFBC) technology and was taken into the experiments. Physical and chemical properties of the material were characterized using several methods, such as fraction analysis, particle size distribution, bulk density, composition, morphology, surface and internal structure by elemental analysis, FT-IR, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis, comprehensive thermal analysis, fly ash texture by BET adsorption isotherms, specific surface area, volume of pores, average pore diameter and pore volume distribution by the BJH method. The influence of pH values on zeta potential of the fly ash surface before and after the adsorption process was conducted. The calculated maximum adsorption capacity of Pb2+ by fly ash reached 51.98 mg/g. The kinetic analysis revealed that the adsorption process is better described by the pseudo-second order equation and it is well fitted to the Freundlich model. In conclusion, fly ash obtained in the CFBC technology is a promising low cost adsorbent for the highly effective recovery of Pb2+ from wastewater.