Effect of soil composition and dissolved organic matter on pesticide sorption

The effect of the solid and dissolved organic matter fractions, mineral composition and ionic strength of the soil solution on the sorption behaviour of pesticides were studied. A number of soils, chosen so as to have different clay mineral and organic carbon content, were used to study the sorption of the pesticides atrazine (6-chloro-N-2-ethyl-N-4-isopropyl-1,3,5-triazine-2,4-diamine), 2,4-D ((2,4-dichlorophenoxy) acetic acid), isoproturon (3-(4-isopropylphenyl)1,1-dimethylurea) and paraquat (1,1'-dimethyl-4,4'-bipyridinium) in the presence of low and high levels of dissolved organic carbon and different background electrolytes. The sorption behaviour of atrazine, isoproturon and paraquat was dominated by the solid state soil components and the presence of dissolved organic matter had little effect. The sorption of 2,4-D was slightly affected by the soluble organic matter in the soil. However, this effect may be due to competition for adsorption sites between the pesticide and the soluble organic matter rather than due to a positive interaction between the pesticide and the soluble fraction of soil organic matter. It is concluded that the major factor governing the sorption of these pesticides is the solid state organic fraction with the clay mineral content also making a significant contribution. The dissolved organic carbon fraction of the total organic carbon in the soil and the ionic strength of the soil solution appear to have little or no effect on the sorption/transport characteristics of these pesticides over the range of concentrations studied. (C) 2002 Elsevier Science B.V. All rights reserved.

On the volume of 4-cycle trades

A 4-cycle trade of volume t corresponds to a simple graph G without isolated vertices, where the edge set can be partitioned into t 4-cycles in at least two different ways such that the two collections of 4-cycles have no 4-cycles in common. The foundation of the trade is v = \V(G)\. This paper determines for which values oft and a there exists a 4-cycle trade of volume t and foundation v.

Quantitative trait loci for agronomic and seed quality traits in an F-2 and F-4 : 6 soybean population

Molecular breeding is becoming more practical as better technology emerges. The use of molecular markers in plant breeding for indirect selection of important traits can favorably impact breeding efficiency. The purpose of this research is to identify quantitative trait loci (QTL) on molecular linkage groups (MLG) which are associated with seed protein concentration, seed oil concentration, seed size, plant height, lodging, and maturity, in a population from a cross between the soybean cultivars 'Essex' and 'Williams.' DNA was extracted from F-2 generation soybean leaves and amplified via polymerase chain reaction (PCR) using simple sequence repeat (SSR) markers. Markers that were polymorphic between the parents were analyzed against phenotypic trait data from the F-2 and F-4:6 generation. For the F-2 population, significant additive QTL were Satt540 (MLG M, maturity, r(2)=0.11; height, r(2)=0.04, seed size, r(2)=0.061, Satt373 (MLG L, seed size, r(2)=0.04; height, r(2)=0.14), Satt50 (MLG A1, maturity r(2)=0.07), Satt14 (MLG D2, oil, r(2)=0.05), and Satt251 (protein r(2)=0.03, oil, r(2)=0.04). Significant dominant QTL for the F-2 population were Satt540 (MLG M, height, r(2)=0.04; seed size, r(2)=0.06) and Satt14 (MLG D2, oil, r(2)=0.05). In the F-4:6 generation significant additive QTL were Satt239 (MLG I, height, r(2)=0.02 at Knoxville, TN and r(2)=0.03 at Springfield, TN), Satt14 (MLG D2, seed size, r(2)=0.14 at Knoxville, TN), Satt373 (MLG L, protein, r(2)=0.04 at Knoxville, TN) and Satt251 (MLG B I, lodging r(2)=0.04 at Springfield, TN). Averaged over both environments in the F-4:6 generation, significant additive QTL were identified as Satt251 (MLG B 1, protein, r(2)=0.03), and Satt239 (MLG 1, height, r(2)=0.03). The results found in this study indicate that selections based solely on these QTL would produce limited gains (based on low r(2) values). Few QTL were detected to be stable across environments. Further research to identify stable QTL over environments is needed to make marker-assisted approaches more widely adopted by soybean breeders.

Enhanced vector competence of Aedes aegypti (Diptera : Culicidae) from the torres strait compared with mainland Australia for dengue 2 and 4 viruses

Australian Aedes aegypti (L.) mosquitoes colonized from the Torres Strait and three mainland localities (Charters Towers, Townsville, and Cairns) were fed on blood suspensions containing dengue virus type 2 (DEN-2) or dengue virus type 4 (DEN-4). Variation was found in oral susceptibility to DEN-2 (59-99% infection) and DEN-4 (28-79% infection) among Ae. aegypti assayed for virus at 8, 12, 16, or 20 d after ingestion of infected blood. Torres Strait Ae. aegypti were the most susceptible to DEN-2 and were significantly more efficient in transmission to capillary tube at 16 d (76% transmission) than mainland Ae. aegypti populations (20-28% transmission). Torres Strait Ae. aegypti were also the most susceptible to DEN-4, although transmission did not vary significantly from mainland populations at 16 d (12% compared with 0-4%) or 20 d (16% compared with 4-16%). Disseminated infection (i.e., leg infection) with either DEN-2 or DEN-4 was not an accurate predictor of transmission potential. This study demonstrates differences among Australian Ae. aegypti populations in vector competence for DEN-2 and DEN-4. Torres Strait Ae. aegypti were more frequently infected and able to transmit DEN-2 at higher rates than mainland populations. These data indicate that the Torres Strait region is potentially more receptive to dengue transmission than mainland localities, a finding discussed with respect to past outbreaks.

4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes from the cane beetle Antitrogus parvulus - Cuticular hydrocarbons with unprecedented structure and stereochemistry

[GRAPHICS] The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16-pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b.

Provision of 4-1BB ligand enhances effector and memory CTL responses generated by immunization with dendritic cells expressing a human tumor-associated antigen

Up-regulation of receptor-ligand pairs during interaction of an MHC-presented epitope on dendritic cells (DCs) with cognate TCR may amplify, sustain, and drive diversity in the ensuing T cell immune response. Members of the TNF ligand superfamily and the TNFR superfamily contribute to this costimulatory molecule signaling. In this study, we used replication deficient adenoviruses to introduce a model tumor-associated Ag (the E7 oncoprotein of human papillomavirus 16) and the T cell costimulatory molecule 4-IBBL into murine DCs, and monitored the ability of these recombinant DO to elicit E7-directed T cell responses following immunization. Splenocytes from mice immunized with DCs expressing E7 alone elicited E7-directed effector and memory CTL responses. Coexpression of 4-1BBL in these E7-expressing DO increased effector and memory CTL responses when they were used for immunization. 4-1BBL expression up-regulated CD80 and CD86 second signaling molecules in DO. We also report an additive effect of 4-IBBL and receptor activator of NF-kappaB/receptor activator of NF-kappaB ligand coexpression in E7-transduced DC inummogens on E7-directed effector and memory CTL responses and on MHC class II and CD80/86 expression in DCs. Additionally, expression of 4-1BBL in E7-transduced DCs reduced nonspecific T cell activation characteristic of adenovirus vector-associated immunization. The results have generic implications for improved or tumor Ag-expressing DC vaccines by incorporation of exogenous 4-1BBL. There are also specific implications for an improved DC-based vaccine for human papillomavirus 16-associated cervical carcinoma.

Increased expression of the SNARE accessory protein Munc18c in lipid-mediated insulin resistance

Fatty acids inhibit insulin-mediated glucose metabolism in skeletal muscle, an effect largely attributed to defects in insulin-mediated glucose transport. Insulin-resistant mice transgenic for the overexpression of lipoprotein lipase (LPL) in skeletal muscle were used to examine the molecular mechanism(s) in more detail. Using DNA gene chip array technology, and confirmation by RT-PCR and Western analysis, increases in the yeast Sec1p homolog Munc18c mRNA and protein were found in the gastrocnemius muscle of transgenic mice, but not other tissues. Munc18c has been previously demonstrated to impair insulin-mediated glucose transport in mammalian cells in vitro. Of interest, stably transfected C2C12 cells overexpressing LPL not only demonstrated increases in Munc18c mRNA and protein but also in transcription rates of the Munc18c gene. jlr To confirm the relevance of fatty acid metabolism and insulin resistance to the expression of Munc18c in vivo, a 2-fold increase in Munc18c protein was demonstrated in mice fed a high-fat diet for 4 weeks. Together, these data are the first to implicate in vivo increases in Munc18c as a potential contributing mechanism to fatty acid-induced insulin resistance.

The t-SNARE syntaxin 4 is regulated during macrophage activation to function in membrane traffic and cytokine secretion

Activation of macrophages with lipopolysaccharide (LPS) induces the rapid synthesis and secretion of proinflammatory cytokines, such as tumor necrosis factor (TNFalpha), for priming the immune response [1, 2]. TNFalpha plays a key role in inflammatory disease [3]; yet, little is known of the intracellular trafficking events leading to its secretion. In order to identify molecules involved in this secretory pathway, we asked whether any of the known trafficking proteins are regulated by LPS. We found that the levels of SNARE proteins were rapidly and significantly up- or downregulated during macrophage activation. A subset of t-SNAREs (Syntaxin 4/SNAP23/Munc18c) known to control regulated exocytosis in other cell types [4, 5] was substantially increased by LPS in a temporal pattern coinciding with peak TNFalpha secretion. Syntaxin 4 formed a complex with Munc18c at the cell surface of macrophages. Functional studies involving the introduction of Syntaxin 4 cDNA or peptides into macrophages implicate this t-SNARE in a rate-limiting step of TNFalpha secretion and in membrane ruffling during macrophage activation. We conclude that in macrophages, SNAREs are regulated in order to accommodate the rapid onset of cytokine secretion and for membrane traffic associated with the phenotypic changes of immune activation. This represents a novel regulatory role for SNAREs in regulated secretion and in macrophage-mediated host defense.

Dietary interactions influence the effects of bovine folate-binding protein on the bioavailability of tetrahydrofolates in rats

The newborns of mammals have a high folate demand, yet obtain adequate folate nutrition solely from their mothers' milk despite its low folate content. Milk folate is entirely bound by an excess of folate-binding protein (FBP), prompting speculation that FBP may affect the bioavailability of the limited folate supply. Previous research has shown that FBP-bound folic acid is more gradually absorbed, thereby reducing the peak plasma folate concentration and preventing loss into the urine. Natural folates are reduced derivatives of folic acid, with milk predominantly containing 5-methyltetrahydrofolate, yet little research has been carried out to determine the role of FBP in the bioavailability of reduced folates. We studied the effect of FBP on folate nutrition of rats in both single-dose and 4-wk feeding experiments. The effect of FBP was influenced by the presence of other milk components. FBP increased bioavailability of dietary folate when it was consumed with other whey proteins or with soluble casein. However, in the presence of acid-precipitated casein or a whey preparation enriched in lipids, bioavailability was decreased. These results highlight the difficulties of extrapolating from experimental results obtained using purified diets alone and of studying interactions among dietary components. They suggest that the addition of FBP-rich foods to folate-rich foods could enhance the bioavailability of natural folates, but that the outcome of such a combination would depend on interactions with other components of the diet.

Heat-induced changes in UHT milks - Part 1

Raw milk was stored for 0, 2 and 4 days and processed in a UHT pilot plant by either direct or indirect heating. The unstored raw milk was also pasteurised. The thermally induced changes resulting from these treatments were investigated by examining a number of indices of heat damage. Lactulose, furosine, total and free hydroxymethylfurfural (HMF) and acid-soluble beta-lactoglobulin were analysed by high performance liquid chromatography (HPLC) while soluble tryptophan was examined by fluorescence spectroscopy. The directly heated UHT milk showed less heat damage than the indirectly heated milk, while the pasteurised milk displayed the least heat damage. During storage of the UHT milk for 12 weeks at similar to20degreesC, the levels of lactulose remained constant, while the furosine concentration increased. Both the total HMF and undenatured beta-lactoglobulin contents showed a general decrease during storage; however free HMF values initially rose but then decreased after four weeks' storage. As the age of the milk at the time of UHT processing increased, the levels of some of the indicators decreased. It is concluded that lactulose is the most reliable index of heat treatment, as it is virtually unaffected by refrigerated storage of the milk before or ambient storage after UHT processing. Reliance on other indicators may give misleading information on the heat load that UHT milk has received during processing.

Diagnosing the cause of proteolysis in UHT milk

Proteolysis of UHT milk during storage at room temperature is a major factor limiting its shelf-life through changes in its flavour and texture. The latter is characterised by increases in viscosity leading in some cases to gel formation. The enzymes responsible for the proteolysis are the native milk alkaline proteinase, plasmin, and heat-stable, extracellular bacterial proteinases produced by psychrotrophic bacterial contaminants in the milk prior to heat processing. These proteinases react differently with the milk proteins and produce different peptides in the UHT milk. In order to differentiate these peptide products, reversed-phase HPLC and the fluorescamine method were used to analyse the peptides soluble in 12% trichloroacetic acid (TCA) and those soluble at pH 4.6. The TCA filtrate showed substantial peptide peaks only if the milk was contaminated by bacterial proteinase, while the pH 4.6 filtrate showed peptide peaks when either or both bacterial and native milk proteinases caused the proteolysis. Results from the fluorescamine test were in accordance with the HPLC results whereby the TCA filtrate exhibited significant proteolysis values only when bacterial proteinases were present, but the pH 4.6 filtrates showed significant values when the milk contained either or both types of proteinase. A procedure based on these analyses is proposed as a diagnostic test for determining which type of proteinase-milk plasmin, bacterial proteinase, or both-is responsible for proteolysis in UHT milk. (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.

Geometric isomers of chloro(6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine)cobalt(III) tetrachlorozincate(II)

The crystal structures of a pair of cis and trans isomers of the macrocyclic chloropentaamine title complex, as their tetrachlorozincate(II) salts, [CoCl(C11H27N5)][ZnCl4], are reported. The two distinct isomeric forms lead to significant variations in the Co-N bond lengths and, furthermore, hydrogen bonding between the complex ions is influenced by the folded (cis) or planar (trans) conformations of the coordinated ligand.

G-values for scission and crosslinking on γ-radiolysis of Ultem at 303 K

The radiation chemical yields G(S) and G(X) for H-linking and Y-linking models for Ultem have been calculated from molecular weight analysis by gel permeation chromatography. These G-values have been compared with the G-values obtained from analysis of soluble fractions above the gel dose, Which have been reported in previous works. An analysis of the molecular weight data in terms of H-linking and Y-linking mechanisms yielded values of G(S-H) = 1.0 x 10(-3) and G(H) = 6.0 x 10(-3) and G(S-Y) = 1.3 x 10(-2) and G(Y) = 1.8 x 10(-2). The corresponding values obtained from the solubility data were G(SH) = 0.53 x 10(-2), G(H) = 1.39 x 10(-2), G(S-Y) = 4.2 x 10(-2) and G(Y) - 4.6 x 10(-2). The origin of the disagreement between the molecular weight and solubility values is not clear, but it could arise as a result of observed microgel formation below the reported gel dose of 0.13 MGy. Whether the crosslink mechanism proceeds by an H-linking or Y-linking process is also unclear and will require direct observation of the crosslinking structures.