16 research outputs found
Phytochelatins are bioindicators of atmospheric metal exposure via direct foliar uptake in trees near Sudbury, Ontario, Canada
Plants produce phytochelatins in response to copper and nickel, the primary metal pollutants emitted by the dominant smelting operation in Sudbury. Copper and nickel concentrations in soils decline sharply with distance from this facility, primarily as a result of early smelting practices. Phytochelatin concentrations in Sudbury-area trees, however, do not correlate with metal levels in soils. Rather, phytochelatin production in tree leaves is driven by metals currently released to the atmosphere through the 381 m emissions stack. Phytochelatin concentrations in the foliage of three tree species growing in situ are highest 20-30 km from the stack, correlated with maximum acid-leachable concentrations of deposited copper and nickel. Similar results observed in potted trees placed adjacent to indigenous trees confirm that aerially deposited metals are the source of current metal stress patterns. The addition of peat moss filters to potted soils did not alter this response, indicating that direct foliar metal uptake is responsible
Brain stem auditory evoked potentials in patients with multiple system atrophy with progressive autonomic failure (Shy-Drager syndrome).
Effectiveness and Safety of Rizatriptan Benzoate 10 mg in the Treatment of Migraine Headaches
Spatial distribution of benthic cysts of Alexandrium catenella in surface sediments of Puget Sound, Washington, USA
Evolutionary origin of whiteflies (Hemiptera: Sternorrhyncha: Aleyrodidae) inferred from 18S rDNA sequences
Genetic diversity of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations and presence of the B biotype and a non-B biotype that can induce silverleaf symptoms in squash, in Uganda
The extent of genetic variability and host-plant distribution of Bemisia tabaci (Gennadius) genotypes colonising cultivated and uncultivated plant species occurring adjacent to cassava fields in selected cassava-producing areas of Uganda in 2003/04 were investigated using the mitochondrial cytochrome oxidase I (mtCOI) gene as the molecular marker. Eight genotype clusters, Ug1–Ug8, which are supported by high bootstrap values (80), at 3–18% nt divergence, were revealed among the collective Ugandan B. tabaci populations. Ug1 and Ug2 (both cassava-associated) and Ug8 (sweetpotato-associated) have been
reported previously in Uganda. Ug3 was genetically dissimilar to B. tabaci described elsewhere and colonised a single species, Ocimum gratissimum. Ug4–Ug7 formed four closely related subclusters (93–97% nt identity) and diverged by 15–18% from Ug1, Ug2, Ug3 and Ug8, respectively. Ug4 had as its closest relatives (at 97–99% nt identity) the Ivory Coast okra biotype, whereas genotypes Ug5 and Ug6 had as their closest relatives (at 95–99% and 99% nt identity, respectively) the Mediterranean–North Africa–Middle East (MEDNAFR-ME) biotypes, which also include the well-studied B and Q biotypes. Ug7 was closely related (at 98–99% nt identity) to biotype Ms from the
Reunion Island in the Indian Ocean. Ug4 colonised Cucurbita pepo, Cucurbita sativus, Leonotis nepetifolia and Pavonia urens, while Ug7 colonised Commelina benghalensis, Gossypium hirsutum and Phaseolus vulgaris. Ug6, the B-biotype-like genotype colonised Abelmoschus esculentus and C. benghalensis only. None of Ug4–Ug7 genotypes was found associated with, or colonising, cassava or sweetpotato
plants. In addition to colonising sweetpotato, the Ug8 genotypes colonised Lycopersicon esculentum and L. nepetifolia. Ug6 and Ug7, both members of the B biotype/B-like cluster, induced silverleaf symptoms on Cucurbita sp. The discovery of five previously identified B. tabaci genotype clusters, Ug3–Ug7, in Uganda, among which are some of the world’s most economically important biotypes, namely B and Q, is particularly significant in the spread of gemini-viruses with devastating effects to crop production in Africa