Selenium and zinc levels in volatile substance abusers

Plasma and erythrocyte levels of selenium (Se) and zinc (Zn) have not been investigated in volatile (inhalant) substance abusers previously, although changes in the activities of antioxidant enzymes resulting from oxidative damage caused by various constituents of volatile substances have been shown in a few animal and human studies. Concentrations of these two elements in erythrocytes and plasma of 37 adolescents with inhalant abuse were measured by atomic absorption spectrophotometry and compared with those of 37 age-matched healthy controls. Erythrocyte and plasma levels of Se and plasma level of Zn were significantly lower in the study group when compared to the control group. Chronic inhalation of volatile substances can decrease the plasma levels of Se and Zn and, thus, may lead to a decrease in the activity of antioxidant enzyme systems in adolescent abusers. The role of Se and Zn supplementation in children with inhalant abuse remains to be determined considering the reduced antioxidant activity resulting from deficiency of these trace elements.     

Simulation on long-term operation of an anaerobic bioreactor for Korean food wastes

A mathematical model was formulated to simulate the long-term performance of an anaerobic bioreactor designed to digest Korean food wastes. The system variables of various decomposition steps were built into the model, which predicts the temporal characters of solid waste, and volatile fatty acid (VFA) in the reactor, and gas production in response to various input loadings and temperatures. The predicted values of VFA and gas production were found to be in good agreement with experimental observations in batch and repeated-input systems. Finally, long-term reactor performance was simulated with respect to the seasonal temperature changes from 5°C in winter to 25°C in summer at different food waste input loadings. The simulation results provided us with information concerning the success or failure of a process during long-term operation.     

On the specificity of lipid hydroperoxide fragmentation by fatty acid hydroperoxide lyase from Arabidopsis thaliana

Fatty acid hydroperoxide lyase (HPL) is a membrane associated P450 enzyme that cleaves fatty acid hydroperoxides into aldehydes and omega-oxo fatty acids. One of the major products of this reaction is (3Z)-hexenal. It is a constituent of many fresh smelling fruit aromas. For its biotechnological production and because of the lack of structural data on the HPL enzyme family, we investigated the mechanistic reasons for the substrate specificity of HPL by using various structural analogues of HPL substrates. To approach this 13-HPL from Arabidopsis thaliana was cloned and expressed in E. coli utilising a His-Tag expression vector. The fusion protein was purified by affinity chromatography from the E. coli membrane fractions and its pH optimum was detected to be pH 7.2. Then, HPL activity against the respective (9S)- and (13S)-hydroperoxides derived either from linoleic, alpha-linolenic or gamma-linolenic acid, respectively, as well as that against the corresponding methyl esters was analysed. Highest enzyme activity was observed with the (13S)-hydroperoxide of alpha-linolenic acid (13alpha-HPOT) followed by that with its methyl ester. Most interestingly, when the hydroperoxy isomers of gamma-linolenic acid were tested as substrates, 9gamma-HPOT and not 13gamma-HPOT was found to be a better substrate of the enzyme. Taken together from these studies on the substrate specificity it is concluded that At13HPL may not recognise the absolute position of the hydroperoxy group within the substrate, but shows highest activities against substrates with a (1Z4S,5E,7Z)-4-hydroperoxy-1,5,7-triene motif. Thus, At13HPL may not only be used for the production of C6-derived volatiles, but depending on the substrate may be further used for the production of Cg-derived volatiles as well.     

Composition of volatiles of banana cultivars from Madeira Island

The composition of the volatiles of banana fruit from various cultivars grown on Madeira Island has been determined. Using GC-MS, the volatiles were shown to be complex mixtures of several classes of components, mainly esters, alcohols, aldehydes, ketones and acids. The average contents of the total volatiles from cultivars "Dwarf Cavendish", "Giant Cavendish", "Robusta" and "Williams" were 93.0, 116.5, 157.3 and 157.0 mg/kg, respectively. The ester and alcoholic fractions appear to play a decisive role in the organoleptic characteristics of banana fruit, presenting a substantial content ranging from 57.2 to 89.8 mg/ kg and 19.0 to 47.7 mg/kg, respectively, in all cultivars from Madeira Island studied. 3-Methyl butyl butanoate ester was the major constituent.     

An Arabidopsis thaliana gene for methylsalicylate biosynthesis, identified by a biochemical genomics approach, has a role in defense

Emission of methylsalicylate (MeSA), and occasionally of methylbenzoate (MeBA), from Arabidopsis thaliana leaves was detected following the application of some forms of both biotic and abiotic stresses to the plant. Maximal emission of MeSA was observed following alamethicin treatment of leaves. A gene (AtBSMT1) encoding a protein with both benzoic acid (BA) and salicylic acid (SA) carboxyl methyltransferase activities was identified using a biochemical genomics approach. Its ortholog (AlBSMT1) in A. lyrata, a close relative of A. thaliana, was also isolated. The AtBSMT1 protein utilizes SA more efficiently than BA, whereas AlBSMT1 catalyzes the methylation of SA less effectively than that of BA. The AtBSMT1 and AlBSMT1 genes showed expression in leaves under normal growth conditions and were more highly expressed in the flowers. In A. thaliana leaves, the expression of AtBSMT1 was induced by alamethicin, Plutella xylostella herbivory, uprooting, physical wounding, and methyl jasmonate. SA was not an effective inducer. Using a beta-glucuronidase (GUS) reporter approach, the promoter activity of AtBSMT1 was localized to the sepals of flowers, and also to leaf trichomes and hydathodes. Upon thrip damage to leaves, AtBSMT1 promoter activity was induced specifically around the lesions.     

The effect of osmolarity on metabolism and morphology in adhesion and suspension chinese hamster ovary cells producing tissue plasminogen activator

The effects of constant osmolarity, between 300 and500 mOsm/kg, on the metabolism of Chinese HamsterOvary (CHO) cells producing tissue plasminogenactivator (tPA) were compared between adhesion andsuspension cultures. In both suspension and adhesionculture, the specific rates of glucose consumption(_G), lactate production (q_L), and tPAproduction (q_tPA) increased as osmolarityincreased, while these rates decreased when osmolaritywas higher than the respective critical levels. However, specific growth rate () decreased withincrease in osmolarity and this slope grew steeper inthe osmolarity range higher than the critical level. The decrease in in the adhesion culture was morerapid than that in the suspension culture. Thecritical osmolarity for adhesion culture (400 mOsm/kg)was lower than that for suspension culture (450 mOsm/kg). These results indicated that the adhesionculture was more sensitive to increase of osmolaritythan the suspension culture, while the specific ratesobtained from the adhesion cultures were in general1.5- to 3-fold higher than those obtained from thesuspension cultures. Cell volume increased asosmolarity increased in both the suspension andadhesion cultures, as reported previously forsuspension culture of hybridoma cells, but there wasno morphological change in the suspension culture. Incontrast, cell height decreased and cell adhesion areamarkedly increased as osmolarity increased in theadhesion culture. This morphological change inadhesion cultures may be one reason for the highersensitivity of adherent cells to the increase ofosmolarity than suspended cells.     

Anaerobic utilization of essential oils bydenitrifying bacteria

Plant volatile organic compounds are a major carbonsource in nature. We studied the degradability ofthese substances by anaerobic microorganisms inenrichment cultures with representative essential oilsas organic substrates and nitrate as electronacceptor. Lemon and pine needle oil supportedmicrobial growth in the presence of pure oil, whereasparsley seed, camphor, sage, fennel, and mint oilsupported growth only when the essential oils weredissolved in an overlying phase of2,2,4,4,6,8,8-heptamethylnonane. Thyme oil did notsupport denitrification. Analyses of the microbiallydegraded oils revealed the disappearance ofmonoterpenes, of several monoterpenoids, and ofmethoxy-propenyl-benzenes, including apiole andmyristicin. Most-probable-number determinations fordenitrifying communities in sewage sludge and forestsoil yielded 10⁶ to 10⁷monoterpene-utilizing cells ml^-1, representing0.7 to 100% of the total cultivablenitrate-reducing microorganisms. The utilization ofessential oils together with the common occurrence ofthis metabolic trait are indications for anenvironmentally important, but currently unexploredanaerobic turnover of plant volatile organic compoundsin soil.     

Tracing mangrove carbon in suspended matter and aquatic fauna of the Gautami–Godavari Delta,Bay of Bengal (India)

Stable carbon isotopic composition and C/N ratio were used to trace the input of carbon associated with mangrove litter into the estuary of the Godavari–Gautami delta system and Kakinada bay (Andhra Pradesh, India). Suspended organic matter in the mangrove channels was more depleted in ¹³C (average ¹³C = –24.5) than in Kakinada bay which showed ¹³C values for suspended matter (average ¹³C = –22.7) closer to those expected for marine phytoplankton. Suspended organic matter from mangrove channels was enriched in nitrogen (average C/N atom ratio 12.7) and ¹³C (average ¹³C = –24.5) relative to mangrove leaf litter, which had a C/N ratio of 75 and a ¹³C value of –28. Lowest C/N ratios for suspended matter were observed during southwest monsoon when rainfall was highest. Although in general, mangrove litter fall was also lower during this period, no clear correlation was observed between litter fall and C/N ratio of suspended matter. In general, the composition of suspended matter pointed towards phytoplankton as a major component. Isotopic composition of zooplankton suggested selective feeding on ¹³C-enriched, marine phytoplankton in open Kakinada bay and on ¹³C-depleted organic matter, such as estuarine phytoplankton and mangrove litter, in the mangrove channels. From the ¹³C signature, it appeared that mangrove carbon was present to some extent in zooplankton and macrofauna from the mangrove mudflats and channels, but the signal rapidly decreased in Kakinada bay. Nitrogen isotopic composition of zooplankton and macrofauna indicated a progressive enrichment of ¹⁵N away from the mangrove forest towards the northern part of Kakinada bay, in approach of Kakinada city. This is thought to reflect input of anthropogenic nitrogen enriched in ¹⁵N and subsequent uptake of this enriched nitrogen into the aquatic food chain.     

Effect of urban sewage treatment on total and methyl mercury concentrations in effluents

The purpose of this study was to investigate the effect of sewage treatment on total mercury (THg) and methylmercury (MeHg) concentrations in domestic effluents and the contribution of urban sewage treatment facilities to THg and MeHg in rivers. We determined the concentrations of THg and MeHg in unfiltered samples of untreated and treated domestic sewage from the three treatment facilities and receiving river water within the City of Winnipeg. The concentrations of THg in the Red and Assiniboine rivers ranged from 3–31 ng/L. THg was related positively to suspended sediment concentrations in the rivers. The concentrations of MeHg in these rivers were usually 0.2–0.3 ng/L. THg concentrations in raw sewage varied widely, from 2–150 ng/L. Treatment removed an average of 88% of this mercury. MeHg concentrations in raw sewage were 0.5–4.3 ng/L, however, after treatment at two treatment facilities, MeHg was greatly reduced, usually to 0.1–0.4 ng/L. Most treated sewage, therefore, had MeHg concentrations that were similar to levels in the receiving rivers and the effect of discharged effluent was usually a change of about 2% or less on concentrations in the rivers. However, one of the facilities (the West End plant) was discharging higher concentrations of MeHg, up to 2 ng/L, causing calculated increases of up to 11% in the concentration of MeHg in the Assiniboine River.