Interactive effects of ozone and powdery mildew (Sphaerotheca fuliginea) on bottle gourd (Lagenaria siceraria)

Interacting effects of ozone at 0.05, 0.1 and 0.2 ppm and powdery mildew infection were studied with respect to the growth, flowering and fruit-setting of bottle gourd, and ozone injury, fungal colonization, conidia size and germination. Intermittent exposure in closed-top chambers to ozone at 0.1 or 0.2 ppm, and infection by Sphaerotheca fulginea, each caused significant suppressions of plant growth, flowering and fruit-setting. Fungal colonization was increased by exposures to 0.05 ppm ozone, but decreased by 0.2 ppm ozone. Less browning and necrosis (symptoms of ozone phytotoxicity) appeared on the leaves of mildew-inoculated plants exposed to ozone at 0.1 and 0.2 ppm. Conidia collected from plants exposed to 0.1 and 0.2 ppm were smaller, contained fewer fibrosin bodies and showed poor germination in-vitro. Fumigations with ozone at 0.05 ppm increased the germination of conidia collected from the exposed plants or of the conidia directly exposed to ozone on glass slides in microgas exposure cabinets. Distortion and wall rupturing of the conidia were induced by exposure to ozone at 0.2 ppm for 12 h. Ozone at 0.05 ppm and S. fuliginea jointly suppressed the root and shoot growth of bottle gourd significantly more than the sum of individual effects (synergistic interaction). The fungus infection partially protected the plants from injury by ozone at 0.2 ppm, and exposure to ozone at 0.2 ppm inhibited fungal development. Antagonistic reductions of damage to bottle gourd growth by simultaneous mildew infection and ozone at 0.2 ppm were observed. The study revealed that powdery mildew infection may become severe on bottle gourd grown in areas polluted with mild level of ozone (0.05 ppm) whereas, at 0.1 ppm O₃ or more, the disease will be suppressed.     

Climate impact from peat utilisation in Sweden

The climate impact from the useof peat for energy production in Sweden hasbeen evaluated in terms of contribution toatmospheric radiative forcing. This wasdone by attempting to answer the question`What will be the climate impact if onewould use 1 m<sup>2</sup> of mire for peatextraction during 20 years?'. Two differentmethods of after-treatment were studied:afforestation and restoration of wetland.The climate impact from a peatland –wetland scenario and a peatland –forestation – bioenergy scenario wascompared to the climate impact from coal,natural gas and forest residues.Sensitivity analyses were performed toevaluate which parameters that areimportant to take into consideration inorder to minimize the climate impact frompeat utilisation. In a `multiple generationscenario' we investigate the climate impactif 1 Mega Joule (MJ) of energy is produced every yearfor 300 years from peat compared to otherenergy sources.The main conclusions from the study are:?The accumulated radiative forcing from the peatland – forestation – bioenergy scenario over a long time perspective (300 years) is estimated to be 1.35 mJ/m²/m² extraction area assuming a medium-high forest growth rate and medium original methane emissions from the virgin mire. This is below the corresponding values for coal 3.13 mJ/ m²/ m² extraction area and natural gas, 1.71 mJ/ m²/ m² extraction area, but higher than the value for forest residues, 0.42 mJ/ m²/ m² extraction area. A `best-best-case' scenario, i.e. with high forest growth rate combined with high `avoided' methane (CH₄) emissions, will generate accumulated radiative forcing comparable to using forest residues for energy production. A `worst-worst-case' scenario, with low growth rate and low `avoided' CH₄ emissions, will generate radiative forcing somewhere in between natural gas and coal.?The accumulated radiative forcing from the peatland – wetland scenario over a 300-year perspective is estimated to be 0.73 –1.80 mJ/ m²/ m² extraction area depending on the assumed carbon (C) uptake rates for the wetland and assuming a medium-high methane emissions from a restored wetland. The corresponding values for coal is 1.88 mJ/ m²/ m² extraction area, for natural gas 1.06 mJ/ m²/ m² extraction area and for forest residues 0.10 mJ/ m²/ m² extraction area. A `best-best-case' scenario (i.e. with high carbon dioxide CO<sub>2</sub>-uptake combined with high `avoided' CH₄ emissions and low methane emissions from the restored wetland) will generate accumulated radiative forcing that decreases and reaches zero after 240 years. A `worst-worst-case' (i.e. with low CO<sub>2</sub>-uptake combined with low `avoided' CH₄ emissions and high methane emissions from the restored wetland) will generate radiative forcing higher than coal over the entire time period.?The accumulated radiative forcing in the `multiple generations' – scenarios over a 300-year perspective producing 1 MJ/year is estimated to be 0.089 mJ/ m<sup>2</sup> for the scenario `Peat forestation – bioenergy', 0.097 mJ/ m² for the scenario `Peat wetland with high CO<sub>2</sub>-uptake' and 0.140 mJ/ m<sup>2</sup> for the scenario `Peat wetland with low CO₂-uptake'. Corresponding values for coal is 0.160 mJ/ m², for natural gas 0.083 mJ/ m² and for forest residues 0.015 mJ/ m². Using a longer time perspective than 300 years will result in lower accumulated radiative forcing from the scenario `Peat wetland with high CO₂-uptake'. This is due to the negative instantaneous forcing that occurs after 200 years for each added generation.?It is important to consider CH₄ emissions from the virgin mire when choosing mires for utilization. Low original methane emissions give significantly higher total climate impact than high original emissions do.?Afforestation on areas previously used for peat extraction should be performed in a way that gives a high forest growth rate, both for the extraction area and the surrounding area. A high forest growth rate gives lower climate impact than a low forest growth rate.?There are great uncertainties related to the data used for emissions and uptake of greenhouse gases in restored wetlands. The mechanisms affecting these emissions and uptake should be studied further.     

Structural chromosomal mosaicism and prenatal diagnosis

True structural chromosomal mosaicism are rare events in prenatal cytogenetics practice and may lead to diagnostic and prognostic problems. Here is described the case of a fetus carrying an abnormal chromosome 15 made of a whole chromosome 2p translocated on its short arm in 10% of the cells, in association with a normal cell line. The fetal karyotype was 46,XX,add(15)(p10).ish t(2;15)(p10;q10)(WCP2+)[3]/46,XX[27]. Pregnancy was terminated and fetus examination revealed a growth retardation associated with a dysmorphism including dolichocephaly, hypertelorism, high forehead, low-set ears with prominent anthelix and a small nose, which were characteristic of partial trisomy 2p. Possible aetiologies for prenatal mosaicism involving a chromosomal structural abnormality are discussed. Copyright © 2004 John Wiley & Sons, Ltd.