Mapping QTLs for Witches' Broom (Crinipellis Perniciosa) Resistance in Cacao (Theobroma Cacao L.)

Molecular markers (RAPD, AFLP and microsatellites) were used to generate a linkage map and to identify QTLs associated to witches' broom (Crinipellis perniciosa) resistance in cacao (Theobroma cacao), using 82 individuals of an F₂ population derived from the clones ICS-1 (susceptible) and Scavina-6 (resistant). Fifteen evaluations of the number of brooms have been carried out in six years (1997–2002). In order to increase the precision and accuracy in the measures of resistance, each F₂ plant was cloned in three replications in a randomized block design with single-tree plots and evaluated over 2 years. Three hundred and forty-two markers were obtained, being 33 microsatellites, 77 AFLPs and 232 RAPDs. The distribution of the number of brooms in the F₂ population was skewed to resistance, suggesting the involvement of major genes controlling resistance and the repeatability estimated for resistance was 44%. A strong putative QTL was detected as being related to witches' broom resistance. Associated to this QTL, the microsatellite mTcCIR35 explained 35.5% of the phenotypic variation in resistance. This marker is being used for marker-assisted selection in Scavina-6 progenies, including those selected in private plantations, as an auxiliary tool to the phenotypic selection.     

Influence of soil moisture on sulphur oxidation in brown earth soils exposed to atmospheric pollution

Summary Laboratory studies were conducted to determine the influence of soil moisture on S oxidation in atmospheric-polluted brown earth soils. Elemental S was oxidized to sulphate over a wide range of soil moisture treatments (10%–60% w/w), but occurred optimally at around 40%–50% soil moisture content (0.08 MPa). Thiosulphate and tetrathionate were found only in soils incubated at low moisture contents. S-oxidation generally acidified the soils, but an increase in soil pH occurred at high moisture levels, where soils were waterlogged. The S oxidative ability of soil samples collected at monthly intervals and incubated with elemental S in the field-moist state was also strongly influenced by soil moisture content. The rate of sulphate production was greatest in the brown earth soil exposed to heavy atmospheric pollution from a coking works.     

A Comparison of Cadmium in Ecosystems on Metalliferous Mine Tailings in Wales and Ireland

A comparative study of the concentrations of cadmium in ecosystems developed on tailings from lead/zinc mines was undertaken. Mine soils, vegetation, ground-dwelling invertebrates and Apodemus sylvaticus from nine historic and abandoned mines in Wales and a modern Irish mine site were sampled in order to evaluate and compare exposure risks to wildlife. There were three high soil cadmium sites (155–300 mg kg^-1) all from north-east Wales sites, one intermediate site (21 mg kg^-1) the Irish mine tailings, with the other sites having low (background) cadmium levels. The cadmium levels reflected differencesin ore minerology and in particular the presence of the zinc ore, sphalerite. The highest plant and invertebrate cadmium levels generally occurred in the three high soil cadmium sites. However, occasional high levels were found in plant and invertebrate samples from one or more of the low cadmium sites. Of particular significance was, despite the relatively high soil cadmium, the very low cadmium concentrations in the plants and invertebrates from the Irish tailings. Evidence of food-chain transfer and even biomagnification in invertebrates did not lead to high cadmium levels in kidneys of A. sylvaticus. Onlyat one high site were the kidney cadmium residues significantly higher than the reference site.     

Changes in the free amino acid content of soil following treatment with fungicides

Both quantitative and qualitative changes in the free amino acid content of soil followed treatment with the fungicides Benomyl, Thiram and Verdasan. The amounts of amino acid-N extracted following the additions of high concentrations of the fungicides were in general lower than the controls over the 28-day incubation period. Low rates of application however, resulted in marked increase in the amounts of amino acid-N extracted. A total of nine different amino acids were extracted seven of which were found consistently in the control soils. Glycine and threonine were markedly favoured by all treatments, whereas the frequency of extraction of the other seven amino acids was dependent upon the fungicide used and its concentration. The results are discussed in relation to the changes in the microbiology of soils which are known to be brought about following partial sterilization with fungicides.     

Microbial S-oxidation in soils exposed to heavy atmospheric pollution

Soils exposed to atmospheric pollution (> 125 SO₂μg m^?3). contained significantly greater numbers of thiobacilli and sulphur-oxidizing fungi than did similar but unpolluted soils. S-Oxidizing heterotrophic bacteria and actinomycetes were, however, infrequently isolated from either polluted or unpolluted soils. Polluted soils contained more fungi (total count) than unpolluted soils but contained fewer heterotrophic bacteria (total count).The distribution of S-oxidizing micro-organisms was closely associated in polluted soils with total S, S₂O^2?₃, S₄O³ amd SO^2?₄ concentrations. These ions increased in concentration below the canopy of polluted sycamore, while soil pH was lower.Rhodanese activity was higher in polluted than in unpolluted soils. The results indicate that microbial S-oxidation is actively occurring in soils exposed to heavy atmospheric pollution.     

Closed reduction and blind cross-pinning for repair of a proximal tibial fracture in a foal

A 4-day-old foal underwent repair of a proximal metaphyseal fracture of the tibia. After closed reduction, fixation was achieved by use of blind cross-pinning. Thirty-five days after surgery, radiography demonstrated complete healing. The foal was mildly lame 4 months after repair of the fracture. Blind cross-pinning may be considered as a method of repair for certain long bone fractures in small foals.     

Forest loss and fragmentation can promote the crowding effect in a forest-specialist primate

Landscape Ecology - Forest loss and fragmentation are rapidly expanding across the tropics. Although forest loss is a major driver of the current biodiversity crisis, the effect of fragmentation...     

Just Add Water and Salt: the Optimisation of Petrogenic Hydrocarbon Biodegradation in Soils from Semi-arid Barrow Island, Western Australia

We investigated the potential of soil moisture and nutrient amendments to enhance the biodegradation of oil in the soils from an ecologically unique semi-arid island. This was achieved using a series of controlled laboratory incubations where moisture or nutrient levels were experimentally manipulated. Respired CO₂ increased sharply with moisture amendment reflecting the severe moisture limitation of these porous and semi-arid soils. The greatest levels of CO₂ respiration were generally obtained with a soil pore water saturation of 50?C70%. Biodegradation in these nutrient poor soils was also promoted by the moderate addition of a nitrogen fertiliser. Increased biodegradation was greater at the lowest amendment rate (100 mg N kg^?1 soil) than the higher levels (500 or 1,000 mg N kg^?1 soil), suggesting the higher application rates may introduce N toxicity. Addition of phosphorous alone had little effect, but a combined 500 mg N and 200 mg P kg^?1 soil amendment led to a synergistic increase in CO₂ respiration (3.0×), suggesting P can limit the biodegradation of hydrocarbons following exogenous N amendment.