Effect of monosodium methanarsonate application on cuticle wax content of cocklebur and cotton plants

Leaf cuticle waxes were extracted from monosodium methanearsonate (MSMA)-resistant (R) and -susceptible (S) common cocklebur (Xanthium strumarium L.) and cotton (Gossypium hirsutum L.) plants at 0, 3, 5, and 7 days after treatment (DAT) following 1x and 2x MSMA applications. Wax constituents were analyzed by gas chromatography (GC) with flame ionization detection and compared to alkane and alcohol standards of carbon lengths varying from C21 to C30. Differences in waxes were calculated and reported as change per ng mm2-1. Tricosane (C23) was found to increase following MSMA applications. All other alkanes decreased by 7 DAT, with some showing a linear effect over time in the R-cocklebur. Alcohol constituents were also observed to decrease by 7 DAT. Total arsenic in the extracted wax fraction was determined, with greatest quantities detected in the R-cocklebur. Wax changes are not believed to play a role in cotton tolerance, since changes in cuticle concentrations were minimal. Cocklebur resistance to MSMA is not due to cuticle constituents; the wax changes are a secondary effect in response to herbicide application.     

MSMA Resistance Studies

Abstract

Monosodium methanearsonate (MSMA)-resistant and -susceptible common cocklebur (Xanthium strumarium L.) and cotton (Gossypium hirsutum L.) were treated with MSMA. Plant parameters analyzed were: glutathione synthetase activity, selected amino acid (arginine, glutamic acid, alanine, citrulline, glutamine, and glutathione) content and arsenic content (MSMA, total arsenic, and arsonate). No reduction of arsenic from the parent pentavalent form present in MSMA to the trivalent form was detected. Arginine, glutamic acid, and glutamine content increased in tissue three days after MSMA treatment. Glutathione content decreased during the first three days after treatment; however, five days after treatment the resistant biotype of cocklebur and cotton had elevated glutathione levels (8–20 times greater, respectively). Glutathione Synthetase activity was higher in cotton than in either of the cocklebur biotypes; MSMA did not affect its activity in cotton or either cocklebur biotype. Resistant biotypes have a slightly higher activity than the susceptible biotype. Tolerance of cotton to MSMA may be related to glutathione synthetase activity and possibly to the presence of phytochelatins. Also, increased glutathione levels in the resistant biotype may implicate phytochelatin involvement in the resistance mechanism.     

MSMA resistance studies

Monosodium methanearsonate (MSMA)-resistant and -susceptible common cocklebur (Xanthium strumarium L.) and cotton (Gossypium hirsutum L.) were treated with MSMA. Plant parameters analyzed were: glutathione synthetase activity, selected amino acid (arginine, glutamic acid, alanine, citrulline, glutamine, and glutathione) content and arsenic content (MSMA, total arsenic, and arsonate). No reduction of arsenic from the parent pentavalent form present in MSMA to the trivalent form was detected. Arginine, glutamic acid, and glutamine content increased in tissue three days after MSMA treatment. Glutathione content decreased during the first three days after treatment; however, five days after treatment the resistant biotype of cocklebur and cotton had elevated glutathione levels (8-20 times greater, respectively). Glutathione Synthetase activity was higher in cotton than in either of the cocklebur biotypes; MSMA did not affect its activity in cotton or either cocklebur biotype. Resistant biotypes have a slightly higher activity than the susceptible biotype. Tolerance of cotton to MSMA may be related to glutathione synthetase activity and possibly to the presence of phytochelatins. Also, increased glutathione levels in the resistant biotype may implicate phytochelatin involvement in the resistance mechanism.     

Surface structures and epicuticular wax composition of spruce needles after long-term treatment with ozone and acid mist

Epicuticular wax structures and epicuticular wax composition were studied in needles of Picea abies (L.) Karst. plants after a long-term fumigation experiment. SEM observations showed aggregated as well as undamaged waxes without any relation to treatments. The chemical wax analysis revealed clone specific differences, but only one compound, the nonacosan-10-ol (C(29)-ol), was found enriched in ozone/acid mist treatments.     

Responses of spruce seedlings (Picea abies) to exhaust gas under laboratory conditions--II. Ultrastructural changes and stomatal behaviour

This study examines the effects of exhaust gas exposure on the epistomatal wax structure and mesophyll ultrastructure in needles of Norway spruce (Picea abies (L.) Karst.) seedlings. Stomatal diffusive resistance was also measured. Two independent exhaust gas fumigations were performed: 100 and 200 ppb measured as NO(x), for 10 days and 50, 100 and 200 ppb NO(x) for 19 days. The obstructive effect of exhaust gas exposure on epistomatal wax tubules was apparent. The stomata became covered by flat and solid wax resulting from the structural degradation of the wax crystalloids. Increasing the exhaust gas concentration in the chamber atmosphere exacerbated the degradation of the wax structure. Exhaust gas exposure induced aggregation and electron translucence of plastoglobuli, swelling of thylakoids, increase of cytoplasmic lipids and slight increase of vesiculation of cytoplasm in mesophyll cells of current and previous year needles. These changes were exemplified in current year needles. Damage to the epicuticular waxes and mesophyll ultrastructure of spruce needles most likely reflects the NO(x) and volatile hydrocarbon fraction. The alterations in epicuticular waxes and mesophyll ultrastructure can be related to accelerated senescence of the youngest, photosynthetically active, needle generation. The exhaust gas also resulted in decreased diffusive stomatal resistance at night which indicates that the exhaust gas exposure disturbed the gas exchange of spruce seedlings. The results show that even relatively short-term exposure to realistic concentrations of exhaust gas in the atmosphere can induce rather severe injuries to the needle surface structure as well as ultrastructure at the cellular level.     

Inhibition kinetics of acid and alkaline phosphatases by atrazine and methomyl pesticides

The main objective of this work was to investigate the kinetic characteristics of acid and alkaline phosphatases isolated from different sources and to study the effects of the herbicide atrazine and insecticide methomyl on the activity and kinetic properties of the enzymes. Acid phosphatase (ACP) was isolated from the tomato plant (Solanum lycopersicum L. var. lycopersicum); alkaline phosphatase (ALP) was isolated from two sources, including mature earthworms (Aporrectodea caliginosa) and larvae of the Egyptian cotton leafworm (Spodoptera littoralis). The specific activities of the enzymes were 33.31, 5.56 and 0.72 mmol substrate hydrolyzed per minute per milligram protein for plant ACP, earthworms ALP and cotton leafworm ALP, respectively. The inhibition kinetics indicated that atrazine and methomyl caused competitive–non-competitive inhibition of the enzymes. The relationships between estimates of K_m and V_max calculated from the Michaelis–Menten equation have been explored. The extent of the inhibition was different, as estimated by the values of the inhibition constant K_i that were found to be 3.34 × 10^?3, 1.12 × 10^?2 and 1.07 × 10^?2 mM for plant ACP, earthworms ALP and cotton leafworm ALP, respectively, with methomyl. In the case of atrazine, K_i were found to be 8.99 × 10^?3, 3.55 × 10^?2 and 1.36 × 10^?2 mM for plant ACP, earthworms ALP and cotton leafworm ALP, respectively.     

Seasonal changes in the chemical composition and reactivity of dissolved organic matter at the land-ocean interface of a subtropical river

Dissolved organic matter (DOM) is a critical component in aquatic ecosystems, yet its seasonal variability and reactivity remain not well constrained. These were investigated at the land-ocean interface of a subtropical river (Minjiang River, SE China), using absorption and fluorescence spectroscopy. The annual export flux of dissolved organic carbon (DOC) from the Minjiang River (5.48 × 10¹⁰ g year^?1) was highest among the rivers adjacent to the Taiwan Strait, with 72% occurring in spring and summer. The freshwater absorption coefficient a₂₈₀, DOC-specific UV absorbance SUVA₂₅₄ and humification index HIX were higher, while the spectral slope S_275–295 and biological index BIX were lower in summer than in winter. This suggests intensified export of terrestrial aromatic and high molecular weight constituents in the rainy summer season. Six fluorescent components were identified from 428 samples, including humic-like C1–C3, tryptophan-like C4 and C6, and tyrosine-like C5. The freshwater levels of four components (C1, C2, C4, and C6) were lower while that of C5 was higher in the wet season than in the dry season, suggesting contrasting seasonal variations of different constituents. Laboratory experiments were performed to assess the effects of photochemical and microbial degradation on DOM. Photo-degradation removed chromophoric and fluorescent DOM (CDOM and FDOM) effectively, which was stronger (i) for high molecular weight/humic constituents and (ii) during summer under higher solar radiation. Microbial degradation under laboratory controlled conditions generally showed little effect on DOC, and had smaller impact on CDOM and FDOM in winter than in summer. Overall, this study showed notable seasonal changes in the chemical composition and reactivity of DOM at the land-ocean interface, and demonstrated the significant effects of photo-degradation.

     

Organic Matter of the Troposphere—II.: Natural Background of biogenic lipid matter in aerosols over the rural western United States

Higher plant waxes are the predominant natural components in the lipid fractions (> C₁₅) of aerosols sampled over rural and oceanic regions. Hydrocarbon, fatty acid, ketone and fatty alcohol fractions of the lipids were characterized in terms of their contents of homologous compound series and specific biogenic molecular markers. Particulate samples from the rural western United States have been analyzed and compared with samples from urban Los Angeles and remote areas over the Atlantic Ocean. The samples from rural sites contained predominantly vascular plant wax and lesser amounts of higher plant sterols and resin residues. Urban samples and, to varying degrees, some rural samples contained primarily higher weight residues of petroleum products. The loadings of hydrocarbons derived from higher plant waxes ranged approximately from 10 to 160 ng m⁻³ of air (for fatty acids, 10–100 ng m⁻³ and for fatty alcohols, 10–200 ng m⁻³). Higher molecular weight lipids (i.e. plant epicuticular wax, terpenes, etc.) from flora comprise a significant component of the organic carbon in rural aerosols. Primary biogenic residues are major components of aerosols in all areas and they are important components in the global cycling of organic carbon.     

Leaching of S-metolachlor,terbuthylazine, desethyl-terbuthylazine,mesotrione, flufenacet,isoxaflutole, and diketonitrile in field lysimeters as affected by the time elapsed between spraying and first leaching event

The effect of elapsed time between spraying and first leaching event on the leaching behavior of five herbicides (terbuthylazine, S-metolachlor, mesotrione, flufenacet, and isoxaflutole) and two metabolites (desethyl-terbuthylazine and diketonitrile) was evaluated in a 2011–2012 study in northwest Italy. A battery of 12 lysimeters (8.4 m² long with a depth of 1.8 m) were used in the study, each filled with silty-loam soil and treated during pre-emergence with the selected herbicides by applying a mixture of commercial products Lumax (4 L ha^?1) and Merlin Gold (1 L ha^?1). During treatment periods, no gravity water was present in lysimeters. Irrigation events capable of producing leaching (40 mm) were conducted on independent groups of three lysimeters on 1 day after treatment (1 DAT), 7 DAT, 14 DAT, and 28 DAT. The series was then repeated 14 days later. Leachate samples were collected a few days after irrigation; compounds were extracted by solid phase extraction and analyzed by high-performance liquid chromatography and gas chromatography–mass spectrometry. Under study conditions, terbuthylazine and S-metolachlor showed the highest leaching potentials. Specifically, S-metolachlor concentrations were always found above 0.25 µg L^?1. Desethyl-terbuthylazine was often detected in leached waters, in most cases at concentrations above 0.1 µg L^?1. Flufenacet leached only when irrigation occurred close to the time of herbicide spraying. Isoxaflutole and mesotrione were not measured (<0.1 µg L^?1), while diketonitrile was detected in concentrations above 0.1 µg L^?1 on 1 DAT in 2011 only.     

Uptake,distribution and elimination of monosodium methanearsonate following long term oral administration of the herbicide to sheep and goats

Abstract

The rate and extent of accumulation and washout of arsenic, during daily oral administration of the herbicide monosodium methanearsonate (MSMA) were evaluated in Iranian dairy sheep and goats. Subjects received a dose of 10 mg of MSMA as arsenic per kg of body weight daily for 28 consecutive days. The total arsenic concentration in blood and milk was measured during and after the period of MSMA administration while arsenic in urine and feces was measured for 10 days following administration of last dosage of MSMA.

Arsenic was accumulated slowly during 28 days of MSMA administration and steady states were essentially complete in sheep after 20 days and in goats following 25 days of MSMA administration. Blood arsenic concentration decreased rapidly after termination of MSMA administration. In both test animals, the half‐lives of washout were smaller than accumulation. The concentration of arsenic in the urine and feces of both species did not increase significantly over controls and animals were free of arsenic relatively shortly after administration stopped.

These data indicate that arsenic from MSMA is mainly absorbed from gastrointestinal tract and is not significantly accumulated in the body. Arsenic is eliminated from body by way of urine and feces with urinary excretion being the most important route.     

Protective role of antioxidants capacity of Hyrtios aff. Erectus sponge extract against mixture of persistent organic pollutants (POPs)-induced hepatic toxicity in mice liver: biomarkers and ultrastructural study

The current study investigates the hepatoprotective effect of Hyrtios aff. Erectus sponge extract against POPs intoxication on endogenous antioxidant enzymes and lipid peroxidation in mice liver tissue. In the present study, the mice BALB/C were assigned into four groups: group I: received saline subcutaneously for 7 days and served as negative control; group II: received subcutaneously for 7 days, 130.6 mg/100 g/b. w/day POPs mixture(mixture of PCB 28, PCB 52,, PCB 101, PCB 118, PCB 153, PCB 138 and PCB 180, alpha-Hexachlorocyclohexane, beta-Hexachloro-cyclohexane, gamma-hexachlorocyclohexane, Aldrin, O,P′-DDE, Dieldrin, P,p DDE, O,P DDD, Endrin, P,p DDD and P,pDDT were extracted from sediments collected from Lake Mariout), and served as induced group; group III: pretreated with Hyrtios aff. Erectus sponge extract for 7 days, as a protection dose and then treated with POPs as group II and served as protective group; and group IV: received i.p Hyrtios aff. Erectus sponge extract of dose 0.7 mg/100 g b.wt/day for 7 days and served as positive control. After 7 days (experimental period), mice were scarified and the liver was harvested for biochemical estimation. Significant reduction in lipid peroxidation (p < 0.002) was noticed compared to POPs-protected group. The antioxidant biomarkers levels were significantly increase as the hepatic GSH and GST increased by 69.9 and 89.9%, respectively. Such increase was accompanied by a decrease in tyrosine kinase activity by 59.82%, additionally remarkable histopathological changes in liver tissue indicate the protective effect of Hyrtios aff. Erectus sponge extract. The results of this study revealed that the Hyrtios aff. Erectus sponge extract has the potential to diminish the destructive effect of POPs intoxication through enhancement of the endogenous antioxidant status. The hepatoprotective activity of Hyrtios aff. Erectus sponge extract is mediated, by the antioxidant effect of its active constituents. The active constituents of Hyrtios aff. Erectus sponge extract were identified by LC-MS/MS.

     

Distribution and toxicity of monosodium methanearsonate following oral administration of the herbicide to dairy sheep and goats

Abstract

Iranian fat‐tailed sheep and dairy goats were administered the herbicide monosodium methanearsonate orally at a dose of 10 mg. MSMA (as arsenic) per kg. of body weight. The concentration time curves of MSMA in the blood of sheep and goats followed a first order composite exponential equation of the form: ^Cb(t) = Ae^‐ αt + B_e ^‐βt ‐ C°be^‐kat.

Absorption, distribution and elimination of MSMA, therefore, corresponds to an open two‐compartment model.

Arsenic from MSMA was readily absorbed from gastrointestinal tract and distributed in the body fluids and the various tissues. Approximately 90% of the arsenic was excreted in the urine within 120 hrs and small amounts were also recovered in feces. Arsenic accumulation in the tissues was low and urinary excretion was the most important exit route. Arsenic concentrations in milk were low when compared to the controls, which indicates that arsenic is not excreted in the milk to significant levels.

The absorption, distribution and overall elimination rate constants for the two animal species studied were statistically different at the 0.95 level of confidence which indicates that there are apparently differences in MSMA metabolism by sheep and goats.     

Long-term evaluation of the needle surface wax condition of Pinus sylvestris around different industries in Lithuania

The aim of our study was to evaluate the annual dynamics of needle surface wax erosion and wettability in Scots pines exposed to a gradient of industrial pollutants emitted from the main factories of Lithuania: a nitrogen fertilizer factory, an oil refinery and a cement factory. Decreased emissions (in the case of the oil refinery and the cement factory) were reflected in the increased structural surface area (SSA, i.e. area covered by tubular waxes) on the needles. The nearly constant amount of emissions from the nitrogen fertilizer factory within the 1994-2000 period corresponded to negligible annual differences in SSA. Annual changes in the hydrophobicity of needles on the investigated transects were small. Despite the decreased pollution within the 7-year period, industrial emissions are still causing significantly accelerated wax erosion and increased wettability in needles sampled from the stands most heavily affected by pollutants.     

Retention and rainfastness of mancozeb as affected by physicochemical characteristics of adaxial apple leaf surface after enhanced UV-B radiation

It is not clear so far whether alteration of leaf micromorphology and surface wax chemistry due to the impact of environmental factors, such as UV-B radiation, affects retention and rainfastness of applied pesticide solutions. In this study; UV-B treated and untreated adaxial leaf surfaces of apple seedlings (Malus domestica Borkh.) were characterized in terms of chemical composition, micromorphological fine structure, hydrophobicity, and wettability. Furthermore, the retention and rainfastness of applied fungicide mancozeb were studied. The samples were examined 0, 24 and 48 h after ultraviolet (UV)-B radiation (0.022 kW m^{? 2} for 150 min) The total wax mass, recovered from the adaxial leaf surface, amounted from 0.38 μ g cm^{? 2} (control) up to 0.49 μ g cm^{? 2} (24 h). Chemical composition of surface wax altered, whereas the contact angle of applied water droplets on leaf surface of UV-B treated plants did not change significantly compared to the control. The alteration of surface wax quantity and quality significantly affected retention of a.i.; it increased at a sampling time of 24 h after UV-B irradiation, whereas rainfastness of the fungicide spray solution was not significantly influenced.     

Composition changes in the cuticular surface lipids of the helophytes <Emphasis Type="Italic">Phragmites australis</Emphasis> and <Emphasis Type="Italic">Juncus effusus</Emphasis> as result of pollutant exposure

Aim of the study  

Helophytes like rush and reed are increasingly used for phytoremediation of contaminated water. This study characterises the response of rush and reed plants to chemical stressors such as chlorobenzene, benzene and methyl-tert-butyl ether. The extractable wax layer of the cuticle was chosen for detailed investigations due to its multiple, particularly, protective functions for plants and its easy availability for analysis.     

Single-solute and bi-solute sorption of phenanthrene and pyrene onto pine needle cuticular fractions

To better understand interaction mechanisms of pine needles with persistent organic pollutants, single-solute and bi-solute sorption of phenanthrene and pyrene onto isolated cuticular fractions of pine needle were investigated. The structures of cuticular fractions were characterized by elemental analysis, Fourier transform infrared spectroscopy and solid-state ¹³C NMR. Polymeric lipids (cutin and cutan) exhibited notably higher sorption capabilities than the soluble lipids (waxes), while cellulose showed little affinity with sorbates. With the coexistence of the amorphous cellulose, the sorption of cutan (aromatic core) was completely inhibited, so the cutin components (nonpolar aliphatic moieties) dominated the sorption of bulk needle cuticle. By the consumption of the amorphous cellulose under acid hydrolysis, sorption capacities of the de-sugared fractions were dramatically enhanced, which controlled by the exposed aromatic cores and the aliphatic moieties. Furthermore, the de-sugared fractions demonstrated nonlinear and competitive sorption due to the specific interaction between aromatic cores and polycyclic aromatic hydrocarbon.     

Wheat leaf epicuticular characteristics as rust inhibitors

Abstract

Wheat (Triticum aestivum L.) trichomes influence wheat leaf rust (Puccinia recondita Rob. ex Desm.) germling elongation as a function of the external element (i.e. ‐ Ca, Si, P, CI) concentration. Basal cells of multicellular trichomes have a high Ca content; and, Ca²⁺ has been shown to inhibit elongation of primary roots. Evaluation of epicuticular wax composition in the intracellular areas of epidermal cells might explain the disorganized growth in those locations.     

Chemical modification of montan resin by peracetic acid and agricultural application of its modified products

ABSTRACT

Montan resin (MR) is a by-product produced during the refinement process of montan wax extracted from lignite and has no usage yet. Chemical modification is an effective method to change the material property for expanding or converting the application area of the material itself. Our previous study found that the high hydrophobicity of MR is the primary limiting factor for its utilization in agriculture. Based on this point, this study attempted to chemically modify MR using the oxidation of peracetic acid, resulting that the MR hydrophilicity was significantly improved, and a water-soluble product (WSP) was obtained. The optimized oxidation conditions of MR, including the reaction temperature (X₁), reaction time (X₂), weight ratio of oxidant and montan resin (X₃), and oxidant concentration (X₄), were determined using single-factor experiments and response surface analysis. The modification degree was evaluated using elemental and oil-water partition coefficient analyses, infrared (IR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS), revealing that the oil-water partition coefficient of the modified product decreased and that the number of chemical constituents with oxygen-containing functional groups clearly increased after modification. Furthermore, the WSP was tested its effects on germination and seedling growth of the wheat seed. Compared with the control group, the WSP showed a promoting effect on the growth and germination of wheat. The WSP concentrations of 600 mg·L^?1 and 300 mg·L^?1 had the most substantial effect on the root and seedling growth of wheat, respectively.

Implications: Montan resin, a useless by-product produced from crude montan wax, was chemically modified via oxidation of peracetic acid. Its hydrophilicity was significantly improved, and a water-soluble product was obtained after the chemical modification. The optimized oxidation conditions of montan resin were determined using single-factor experiments and response surface analysis. The amount of chemical constituents with oxygen-containing functional groups increased in the modified products after modification, as determined by IR and GC-MS analysis, among other methods. The water-soluble modified product showed an obvious effect in promoting growth and germination of wheat at 600 mg·L-1 and 300 mg·L-1, respectively.     

Monitoring of pesticide residues in a cotton crop soil

Abstract

This paper reports on the residues of methyl parathion (O,O‐dimethyl O‐4‐nitrophenyl phosphorothioate), trifluralin (α, α, α‐trifluoro‐2, 6‐dinitro‐N, N‐dipropyl‐p‐toluidine), endosulfan [(1, 4, 5, 6, 7, 7‐hexachloro‐8, 9, 10‐trinorborn‐5‐en‐2, 3‐ylenebismethylene) sulfite] and dimethoate (O, O‐dimethyl S‐methylcarbamoylmethyl phosphorodithioate) in a cotton crop soil. Soil samples (0–15 cm) were collected at different periods from the cotton crop farm and subjected to Soxhlet extraction. The extracted material was analysed after clean‐up by a HP5890 II gas Chromatograph equipped with a ⁶³Ni electron‐capture detector (ECD‐⁶³Ni) and fitted with a 25m x 0,2mm i.d. fused silica capillary column [Ultra‐2 (5% phenylmethyl polysiloxane)]. The recoveries of the pesticide residues from the spiked control soil were determined after Soxhlet extraction and C₁₈ cartridges clean‐up by using radiotracer techniques with the corresponding ¹⁴C‐pesticides. The results show that in the cotton crop soil the pesticide residues under study were present in the range of 0.1 to 0.4 mg ? kg^‐1. Endosulfan was found to be rapidly degraded in the soil and formed a sulfate metabolite.     

Urbanization-related changes in European aspen (Populus tremula L.): Leaf traits and litter decomposition

We investigated foliar and litter responses of European aspen (Populus tremula L.) to urbanization, including factors such as increased temperature, moisture stress and nitrogen (N) deposition. Leaf samples were collected in 2006-2008 from three urban and three rural forest stands in the Helsinki Metropolitan Area, southern Finland, and reciprocal litter transplantations were established between urban and rural sites. Urban leaves exhibited a higher amount of epicuticular waxes and N concentration, and a lower C:N ratio than rural ones, but there was no difference in specific leaf area. Urban litter had a slightly higher N concentration, lower concentrations of lignin and total phenolics, and was more palatable to a macrofaunal decomposer. Moreover, litter decay was faster at the urban site and for urban litter. Urbanization thus resulted in foliar acclimatization in terms of increased amount of epicuticular waxes, as well as in accelerated decomposition of the N-richer leaf litter.