Egg protein insolubility inLymantria dispar versus other forest Lepidoptera

Summary A standard buffer (5 mM phosphate at pH 7) which is used to extract protein from insect eggs provided complete protein solubility for eggs from three of four tree-feeding lepidopteran species: obliquebanded leaf roller (Choristoneura rosaceana), forest tent caterpillar (Malacosoma disstria), and the eastern tent caterpillar (Malacosoma americanum). Under the same extraction protocol, egg proteins from the gypsy moth (Lymantria dispar), remained nearly insoluble. An array of methods typically used to solubilize insect egg proteins were tried and all but the most denaturing (2% SDS) were ineffective. Extraction buffers with typically high pH values were then evaluated. The results indicated that 1) solubility of gypsy moth egg proteins was pH dependent, and full solubility of most egg proteins required the extraction buffer to have a pH of 12 or more prior to the addition of eggs. We also determined that 2) the gypsy moth egg has a buffering capacity which must be surpassed for complete protein extraction, 3) low salt/high pH buffers gave slightly higher total protein values than did high salt/high pH buffers, 4) parental nutritional history (host species utilized) and egg developmental state (pre-embryonatedvs postembryonated/pre-hatch) were unrelated to the requirements for complete egg protein solubilization, and 5) the presence of soluble phenolics, compounds that have the potential to bind to protein and cause insolubility, was confirmed for the gypsy moth egg with 2-D paper chromatography and several other tests. Based on these results, we present a hypothesis about the cause of egg protein insolubility in the gypsy moth.     

Abstracts to forthcoming papers

Soil and sediments collected at a former chlor‐alkali plant in coastal Georgia (United States), revealed the presence of PCDF concentrations as great as 82.3 ng/g, dry wt. PCDF congener profile in soil was typical of “chlorine pattern”; with elevated proportions of OCDF and HpCDF. Concentrations of PCDFs declined gradually by 44‐fold at a distance of about 500 m along the contamination gradient. Of PCDDs/DFs, 2,3,7,8‐substituted PCDFs accounted for 94–98% of the TCDD‐like activity, which declined by 25‐fold, corresponding with the reduction of total PCDF concentrations. Concentrations of PCDDs in sediments were as great as 17 ng/g, with an elevated contribution from OCDD. The magnitude of decline in PCDD concentrations with distance from the source was less pronounced than that for PCDFs. PBDDs and PBDFs were not detected. Polybrominated biphenyl ether (PBBE) and monobromo‐heptachloro dibenzo‐p‐dioxins and dibenzofurans (PXDDs/DFs) were found, though, at low concentrations. Their spatial distribution was similar to those of PCDDs.     

Feasibility of using metals to remediate water containing TCE

The feasibility of treating underground water contaminated by a chlorinated organic compound with bimetallics Fe/Ni, Zn/Ni and Zn single metal was studied. Column tests to simulate a reactive permeable wall in a funnel-and-gate system were used. Research results indicated that bimetallic Fe⁰/Ni⁰ and Zn⁰/Ni⁰ all had a very strong degraded power to trichloroethylene (TCE ) at concentration up to 25 mg/l under different flow rates (27 cm/day–20 m/day). Furthermore, the concentrations of TCE and various ions in the treated effluent were nearly lower than the values specified in related standards for drinking water in Taiwan. These results showed that this technique could be effectively and safely used as an underground water remediation process.     

Enhanced catalytic complete oxidation of 1,2-dichloroethane over mesoporous transition metal-doped γ-Al2O3

High-surface-area mesoprous powders of γ-Al₂O₃ doped with Cu²⁺, Cr³⁺, and V³⁺ ions were prepared via a modified sol-gel method and were investigated as catalysts for the oxidation of chlorinated organic compounds. The composites retained high surface areas and pore volumes comparable with those of undoped γ-Al₂O₃ and the presence of the transition metal ions enhanced their surface acidic properties. The catalytic activity of the prepared catalysts in the oxidation of 1,2-dichloroethane (DCE) was studied in the temperature range of 250-400℃. The catalytic activity and product selectivity were strongly dependent on the presence and the type of dopant ion. While Cu²⁺- and Cr³⁺-containing catalysts showed 100% conversion at 300℃ and 350℃, V³⁺-containing catalyst showed considerably lower conversion. Furthermore, while the major products of the reactions over γ-alumina were vinyl chloride (C₂H₃Cl) and hydrogen chloride (HCl) at all temperatures, Cu- and Cr-doped catalysts showed significantly stronger capability for deep oxidation to CO₂.     

Aerobic biodegradation of vinyl chloride and cis-1,2-dichloroethylene in aquifer sediments

Laboratory batch experiments have been performed with sediment and groundwater obtained from two sites in Denmark to study the aerobic biodegradation of vinyl chloride (VC) and cis-1,2-dichloroethylene (c-1,2-DCE) to assess the natural aerobic biodegradation potential at two sites. The experiments revealed that VC was degraded to below the detection limit within 204 and 57 days at the two sites. c-1,2-DCE was also degraded in the experiments but not completely. At the two sites 50% and 35% was removed by the end of the experimental period of 204 and 274 days. The removal of c-1,2-DCE seems to occur concomitantly with VC indicating that the biodegradation of c-1,2-DCE may depend on the biodegradation of VC. However, in both cases natural groundwater was mixed with sediment and consequently there may be other compounds (e.g. ammonium, natural organic compound etc.) that serves as primary substrates for the co-metabolic biodegradation of c-1,2-DCE. At one of the sites methane was supplied to try to enhance the biodegradation of VC and c-1,2-DCE. That was successful since the time for complete biodegradation of VC decreased from 204 days in the absence of methane to 84 days in the presence of methane. For c-1,2-DCE the amount that was biodegraded after 204 days increased from 50% to 90% as a result of the addition of methane. It seems like a potential for natural biodegradation exists at least for VC at these two sites and also to some degree for c-1,2-DCE.     

Chemical determinants of resistance in winter-dormant seedlings of European white birch (Betula pendula) to browsing by the mountain hare

Summary A sample of one-year-old seedlings of European white birch (Betula pendula) was analyzed to determine the content of sugars, phenolics and terpenoid compounds. Two vertical segments of each seedling were analyzed separately. The number of resin droplets, which correlates strongly and negatively with feeding by the mountain hare, was also counted on the bark of experimental seedlings. The variation in the palatability of birch seedlings to mountain hare was determined primarily by the most abundant terpenoid, papyriferic acid. On the other hand, the resistance to hare feeding at the seedling bases, which are frequently attacked by voles, appeared to be dependent on other components, apparently phenolic substances. Sugars did not affect the resistance of the tested seedlings. The variation among experimental seedlings was much greater for secondary substances, especially terpenoid compounds, than for sugars. It is suggested that this high variation in protective compounds may be an adaptive trait selected for by the feeding of generalist herbivores.     

Ranking of individual mountain birch trees in terms of leaf chemistry: seasonal and annual variation

Summary. The quality of tree leaves as food for herbivores changes rapidly especially during the spring and early summer. However, whether the quality of an individual tree in relation to other trees in the population changes during the growing season and between years is less clear. We studied the seasonal and annual stability of chemical and physical traits affecting leaf quality for herbivores. Rankings of trees in terms of the contents of two major groups of phenolics in their leaves, hydrolyzable tannins and proanthocyanidins (condensed tannins), were very stable from the early spring to the end of the growing season. There were also strong positive within-season correlations in the levels of some other groups of phenolics in the leaves (kaempferol glycosides, myricetin glycosides and p-coumaroylquinic acid derivatives). The contents of individual sugars and the sum content of protein-bound amino acids showed patterns of seasonal consistency in mature leaves, but not in young developing leaves. The seasonal correlations in leaf water content and toughness were also strongest in mature leaves. The correlations between two years at corresponding times of the growing season were strongly positive for the major groups of phenolics throughout the season, but were more variable for the contents of proteins and some sugars. Leaf toughness and water content showed strong positive correlations in mature leaves. Despite the consistency of tree ranking in terms of leaf phenolics, the relative resistance status of trees may, however, change during a growing season because there was a negative correlation between the content of hydrolyzable tannins (early-season resistance compounds) in leaves early in the season and the content of proanthocyanidins (late-season resistance compounds) late in the season, and vice versa. Thus, assuming that phenolics affect herbivore preference and performance, different plants may suffer damage at different times of the growing season, and the overall variation between trees in the fitness consequences may be low. In addition, the adaptation of herbivorous insects to mountain birch foliage in general, as well as to specific tree individuals, may be constrained by variation in the relative resistance status of the trees.     

Experimental design of Fenton and photo-Fenton reactions for the treatment of cellulose bleaching effluents

Multivariate experimental design was applied to the treatment of a cellulose conventional bleaching effluent in order to evaluate the use of the Fenton reagent under solar light irradiation. The effluent was characterised by the general parameters total organic carbon (TOC), chemical oxygen demand and color, and it was analysed for chlorinated low molecular weight compounds using GC–MS. The main parameters that govern the complex reactive system: Fe(II) and H₂O₂ initial concentration, and temperature were simultaneously studied. Factorial experimental design allowed to assign the weight of each variable in the TOC removal after 15 min of reaction. Temperature had an important effect in the organic matter degradation, especially when the ratio of Fenton reagents was not properly chosen. Fenton reagent under solar irradiation proved to be highly effective for these types of wastewaters. A 90% TOC reduction was achieved in only 15 min of treatment. In addition, the GC–MS analysis showed the elimination of the chlorinated organic compounds initially detected in the studied bleaching effluents.     

The Danish incinerator dioxin study. Part 1

During the last two years an extensive series of dioxin measurements has been conducted on Danish municipal and hospital solid waste incinerators. The study was directed toward finding the total annual dioxin emissions from MSWI in Denmark, now estimated to be 3 kg. of dioxines and furanes. This sum is equivalent to 50 g. of 2,3,7,8-TCDD according to the Nordic Equivalents. Measurements were carried out according to a statistical design following a plan of pre-randomized sampling. This procedure allowed causal interpretation of the correlations found between the dioxin emissions and certain operating parameters. The statistical model obtained describes the emissions by variations between incinerators, by variation in time, and by changes in the load, the excess air and the HCl concentration in the flue gas.     

Preliminary report: Dioxins and furans in prescribed burns

The Ontario Ministry of Environment (MOE) recently participated in a joint Canadian/U.S. program to monitor the behavior and environmental impact of prescribed fires. Air, soil and ash samples were collected at the burn sites and analyzed for chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF). Preliminary results indicated that larger air sample volumes were required.