Sorption of antimony species by humic acid

The retention of antimony (a potential toxin) in polluted soils or waterway sediments can involve interaction with several component phases. One of these, humic acid, has been found to adsorb antimony (III) from solutions of Sb(OH)₃ or potassium antimonyl tartrate (C₈H₄K₂Sb₂O₁₂) in accordance with Langmuir type isotherms. Using Sb(OH)₃ solutions (initial Sb levels < 10 μM) the bonding constant value (at pH 4) was 6 × 10⁵, with a calculated saturation capacity of 23 μmol g^?1. In the antimonyl tartrate systems (initial Sb levels 0.5 to 75 μM) the bonding constant value for the sorbed species was 1.6 × 10⁵ and the saturation capacity 53 μmol g^?1. Addition of small amounts of HCl or NaOH (to vary the pH between 3.1 and 5.4) had little effect on the amount sorbed from KSbT solutions but with Sb(OH)₃ solutions uptake was reduced (by about 15%). In the presence of NaCl (0.5 or 0.05M) Sb uptake increased (by about 15%). Antimony (V) (introduced as KSb (OH)₆) was not sorbed from solutions < 10 μM in this salt. Using more concentrated solutions, uptake gradually increased, reaching a plateau value of around 8 μmol g^?1 with solutions initially 50 or 75 μM.     

Mulch type and moisture level affect pupation depth of <Emphasis Type="Italic">Rhagoletis mendax</Emphasis> Curran (Diptera: Tephritidae) in the laboratory

Mulching can be beneficial for organic highbush blueberry production, but its effects on insect pests have received little attention. For pests that pupate in soil, depth may affect pupation success due to differences in temperature and moisture, mortality factors such as predation, or efficacy of controls such as insecticidal soil drenches. We examined how mulch type and moisture affect pupation depth for Rhagoletis mendax Curran (blueberry maggot), an important pest of blueberries. In laboratory studies, pupation depth was measured in wood waste compost, uncomposted pine needles, soil and sand, each at dry, field moisture levels and wet, 99% water holding capacity conditions. Pupation occurred more deeply but with greater variability in pine needle mulch compared to compost mulch, soil, or sand. Approximately 50% of maggots pupated on the surface of wet soil, however, maggots burrowed more deeply in wet than in dry pine needles. Moisture level did not significantly affect pupation depth in compost or sand. Some larvae unexpectedly escaped the stacks of cups used to assess pupation depth or died before forming a puparium. Less than 70% of stacks with dry pine needles contained pupae, and fewer pupae were recovered from wet than dry compost and soil. These results suggest that mulch material and/or moisture levels can have significant impacts on R. mendax pupation depth with potential implications for its management.     

Identification of roots from grass swards using PCR-RFLP and FFLP of the plastid <Emphasis Type="Italic">trn</Emphasis> L (UAA) intron

Background  

The specific associations between plant roots and the soil microbial community are key to understanding nutrient cycling in grasslands, but grass roots can be difficult to identify using morphology alone. A molecular technique to identify plant species from root DNA would greatly facilitate investigations of the root rhizosphere.     

Developing new markers and QTL mapping for greenbug resistance in sorghum [Sorghum bicolor (L.) Moench]

Greenbug is a major damaging insect to sorghum production in the United States. Among various virulent greenbug biotypes, biotype I is the most predominant and severe for sorghum. To combat with the damaging pest, greenbug resistant sources were obtained from screening sorghum germplasm collection. This experiment was conducted to identify the genomic regions contributing resistance to greenbug biotype I in a sorghum accession, PI 607900. An F₂ mapping population consisting of 371 individuals developed from a cross of the resistant line with an elite cultivar, BTx623 (susceptible) were tested and scored for their response to greenbug feeding in the greenhouse. Significant differences in resistance were observed between the two parental lines and among their F₂ progeny in response to greenbug feeding at 7, 10, 14 and 21 days after infestation. A linkage map spanning a total length of 729.5 cM across the genome was constructed with 102 polymorphic SSR markers (69 genomic and 33 EST SSRs). Of those microsatellite markers, 48 were newly developed during this study, which are a useful addition for sorghum genotyping and genome mapping. Single marker analysis revealed 29 markers to be significantly associated with the plant response to greenbug feeding damage. The results from interval mapping, composite interval mapping and multiple interval mapping analyses identified four major QTLs for greenbug resistance on chromosome 9. These QTLs collectively accounted for 34–82 % of the phenotypic variance in greenbug resistance. Minor QTLs located on chromosome 3 explained 1 % of the phenotypic variance in greenbug resistance. The major allele for greenbug resistance was on chromosome 9 close to receptor-like kinase Xa21-binding protein 3. These markers are useful to screen more resistant genotypes. Furthermore, the markers tagged to QTL regions can be used to enhance the sorghum breeding program for greenbug resistance through marker-assisted selection and map-based cloning.     

Effects of metaldehyde and acetaldehyde on specific membrane currents in neurones of the pond snail Lymnaea stagnalis

Bath application of metaldehyde or acetaldehyde led to tonic depolarization and bursting activity in identified neurones in the isolated central nervous system of Lymnaea stagnalis. This activity was sometimes accompanied by paroxysmal depolarizing shifts in membrane potential. Those neurones which possessed type 2 action potentials showed marked spike broadening in response to metaldehyde, but little increase in action potential duration in the presence of acetaldehyde. Under voltage clamp, metaldehyde caused a reduction in the delayed rectifier and A-currents, both of which are outward potassium currents. Acetaldehyde also reduced the delayed rectifier but had no effect on the A-current. In type 2 neurones, voltage-dependent calcium current appeared to increase in the presence of metaldehyde, but was decreased by acetaldehyde. The action of metaldehyde and acetaldehyde on firing activity, as well as their differential effects on action potential duration, may be partly explained by alterations in these specific membrane currents.     

Forest Grabbing Through Forest Concession Practices: The Case of Guyana

Colonial governments asserted sovereignty and property rights gradually over the territory of Guyana, disregarding preexisting Indigenous Rights. Although a Forest Department modeled on the Indian Forest Service was established, there was no equivalent settlement process to determine the rights of forest peoples. State Forest area is declared by administrative fiat. These two elements have enabled State-endorsed forestland grabbing. Logging was scattered and selective until the early 1980s. A neoliberal economic program from the 1980s has allowed Asian companies to gain control over at least 80% of large-scale forestry concessions, equivalent to one-third of the 15.8 million hectares (Mha) of State-administered public forests. The relative success of the Asian companies can be understood in terms of available capital, willingness to invest, knowledge of markets, and willingness to corrupt. The relative failure of the preexisting Guyanese-owned businesses can be understood in terms of lack of capital, inability to save and unwillingness to invest, lack of knowledge of marketing, and lack of cooperation within the sector. Some conclusions from the Guyana story are relevant to other countries related to resource-hungry transnational enterprises.     

The effect of topical pimecrolimus on keratoconjunctivitis sicca and chronic superficial keratitis in dogs: results from an exploratory study

OBJECTIVE: Pimecrolimus is an ascomycin derivative that interferes selectively with the activation of T cells and mast cells and inhibits the production of inflammatory cytokines. This study evaluated the efficacy of an experimental ophthalmic formulation of pimecrolimus in treating keratoconjunctivitis sicca (KCS) and chronic superficial keratitis (CSK) in dogs. ANIMALS AND PROCEDURES: Eight dogs with KCS and six with CSK were included. The dogs were of various breeds, suffered from chronic conditions, and had been pretreated unsuccessfully. The affected eyes were treated with 1 drop of an experimental, corn oil-based pimecrolimus 1% formulation three times a day. Parameters evaluated included Schirmer tear test (STT), ocular discharge, conjunctival inflammation, corneal inflammatory cell infiltrate and scarring, and comfort level. RESULTS: The effect of pimecrolimus 1% was pronounced (increase in STT values to higher than 4 mm/min, no signs of inflammation) or moderate (increase in STT values of 3-4 mm/min, mild signs of corneal/conjunctival inflammation) in a total of 6/8 animals with KCS. In 4/6 animals with CSK, the effect was either pronounced (total regression of fibrovascular infiltration into the cornea, no corneal scarring) or moderate (distinct regression of pannus, mild corneal scarring). The response to treatment was unsatisfactory in four of 14 animals. CONCLUSION: Results of this exploratory study suggest that topical 1% pimecrolimus may be a new effective treatment for keratoconjunctivitis sicca and chronic superficial keratitis in dogs.     

Lichtmikroskopische Untersuchungen über das Glaukom der Katze

In the paper presented, the histological findings in four cats with glaucoma are reported by means of HE-stained paraffin embedded sections. To each case a clinical anamnesis is given. The authors describe primary glaucomas as well as secondary glaucomas of different aetiology. A dysplastic pectinate ligament can be identified for the first time in a cat. Clinical and histological findings are discussed and compared to the findings in dogs.     

Effects of metaldehyde and acetaldehyde on feeding responses and neuronal activity in the snail,lymnaea stagnalis

The pond snail Lymnaea stagnalis was fed on maize pellets containing metaldehyde. With increasing concentration of metaldehyde there was a decrease in the meal length, number of bites per meal and amount of pellet eaten. The irregularity of biting and the amount of time spent pausing during the meal increased. Meals on maize pellets in the presence of acetaldehyde (one of the metabolites of metaldehyde) were shorter than control meals on maize pellets alone. The symptoms of poisoning after ingestion of metaldehyde or in the presence of acetaldehyde were similar. There was an increase in mucus secretion. Animals showed muscular spasms, undirected mouthing movements and uncoordinated locomotion. This was followed by a period of immobility. The isolated central nervous system of L. stagnalis was used to study the effects of metaldehyde and acetaldehyde on the neural activity underlying feeding. Application of metaldehyde or acetaldehyde led to an increase in firing activity and development of paroxysmal depolarising shifts in buccal motoneurons. It is argued that this type of activity could explain some of the symptoms of poisoning seen in the whole animal after ingestion of metaldehyde, and that acetaldehyde may be responsible for some of the toxic effects of metaldehyde. These results suggest that the CNS of L. stagnalis provides a useful model for screening molluscicides for their effects on a functional neuronal network.