Toxicokinetics, recovery, and metabolism of metamitron in goat

Toxicokinetic behavior and metabolism studies of metamitron and its effect on the cytochrome P(450) content of liver microsomal pellet were carried out in black Bengal goats after a single oral administration at 278 mg kg(-1) and consecutive oral administration of 30 mg kg(-1) for 7 days. Metamitron was detected in the blood sample at 0.08 h (12.0 +/- 0.87 microg mL(-1)), maximum at 4 h (84.3 +/- 8.60 microg mL(-1)) and minimum (14.6 +/- 1.67 microg mL(-1)) at 36 h blood sample after a single oral administration. The absorption rate constant was 0.69 +/- 0.09 h(-1). The Vd(area) (2.00 +/- 0.08 L kg(-1)) and t(1/2)beta (8.98 +/- 0.70 h) values suggested wide distribution and long persistence of the compound in the body. The values of T approximately B (0.80 +/- 0.04), F(c) (0.55 +/- 0.01), Cl(B) (0.15 +/- 0.00 L kg(-1) h(-1)), and K(21) (0.41 +/- 0.03 h(-1)) suggested that metamitron retained in the blood compared to that in the tissue. Maximum concentration of metamitron residue was found in the adrenal gland followed by bile on day 4 of single oral administration. The higher Cl(R) compared to Cl(H) value indicated the excretion of the major portion (34-40%) through urine compared to feces (20-26%). Maximum concentrations of metamitron and its metabolite, deaminometamitron, were excreted through urine and feces at 48 and 24 h samples, respectively. The recovery of metamitron including its metabolite in terms of parent compound varied from 69.3 to 80.1%, of which contribution of metabolite in terms of parent compound varied from 53.1 to 63.0%. Repeated oral administration of metamitron at 30 mg kg(-1) for 7 days caused induction of the cytochrome P(450) content of liver microsomal pellet of goat, suggesting oxidative deamination of metamitron.     

Toxico-kinetics, recovery, and metabolism of napropamide in goats following a single high-dose oral administration

Toxicokinetic behavior, recovery and metabolism of napropamide (a pre-emergent herbicide) and its effect on Cytochrome P(450) of liver microsomal pellet were studied following a single high-dose oral administration of 2.5 g kg(-1) and continuous (7 days) oral administration of 500 mg kg(-1) in black Bengal goat. Napropamide was detected in blood at 15 min and the maximum quantity was recovered at 3 h after administration. The absorption rate constant (Ka) value was low indicating poor absorption from the gastrointestinal tract. High elimination half-life (t(1/2) beta) and low body clearance (Cl(B)) values coupled with higher transfer of compound from tissue to central compartment (K(21)) suggest that napropamide persisted in the blood for a long time, i.e., after 72 h of oral administration. The recovery percentage of napropamide, including metabolites, from goats varied from 75.94 to 80.08 and excretion of the parent compound through feces varied from 18.86 to 21.59%, indicating that a major portion of the orally administered napropamide was absorbed from the gastrointestinal tract of goat. Napropamide significantly increased the Cytochrome P(450) content of liver microsomal pellet. The recovery of metabolites from feces, urine, and tissues ranged from 4.2--6.2, 40.81--49.42, and 2.7--11.6%, respectively, during a 4--7 day period. The material balance of napropamide (including metabolites) following a single high-dose oral administration at 2.5 g kg(-1) during 4--7 days after dosing was found to be in the range of 75--80%.     

Tissue distribution, elimination, and metabolism of sodium [36Cl]perchlorate in lactating goats

Perchlorate has contaminated water sources throughout the United States but particularly in the arid Southwest, an area containing large numbers of people and few water sources. Recent studies have demonstrated that perchlorate is present in alfalfa and that perchlorate is secreted into the milk of cows. Studies in lactating cows have indicated that only a small portion of a perchlorate dose could be accounted for by elimination in milk, feces, or urine. It was hypothesized that the remainder of the perchlorate dose was excreted as chloride ion. The purpose of this study was to determine the fate and disposition of (36)Cl-perchlorate in lactating dairy goats. Two goats (60 kg) were each orally administered 3.5 mg (16.5 muCi) of (36)Cl-perchlorate, a dose selected to approximate environmental perchlorate exposure but that would allow for adequate detection of radioactive residues after a 72 h withdrawal period. Blood, milk, urine, and feces were collected incrementally until slaughter at 72 h. Total radioactive residue (TRR) and perchlorate concentrations were measured using radiochemical techniques and liquid chromatography mass spectrometry (LC-MS-MS). Peak blood levels of TRR occurred at 12 h ( approximately 195 ppb) postdose; peak levels of parent perchlorate, however, occurred after only 2 h, suggesting that perchlorate metabolism occurred rapidly in the rumen. The serum half-life of perchlorate was estimated to be 2.3 h. After 24 h, perchlorate was not detectable in blood serum but TRR remained elevated (160 ppb) through 72 h. Milk perchlorate levels peaked at 12 h (155 ppb) and were no longer detectable by 36 h, even though TRRs were readily detected through 72 h. Perchlorate was not detectable in skeletal muscle or liver at slaughter (72 h). Chlorite and chlorate were not detected in any matrix. The only radioactive residues observed were perchlorate and chloride ion. Bioavailability of perchlorate was poor in lactating goats, but the perchlorate that was absorbed intact was rapidly eliminated in milk and urine.     

Evaluation of drying methods and toxicity of rayless goldenrod ( Isocoma pluriflora ) and white snakeroot ( Ageratina altissima ) in goats

White snakeroot and rayless goldenrod cause "trembles" and "milk sickness" in livestock and humans, respectively. The toxin in white snakeroot and rayless goldenrod was identified in 1927 and 1930, respectively, as tremetol. It was reported that the toxin in white snakeroot disappears as it is dried and that completely dried plants were incapable of producing trembles or milk sickness. Conversely, it has been reported that the rayless goldenrod toxin was not destroyed by drying and that the plant is toxic either fresh or dry. In this study the concentrations of tremetone, dehydrotremetone, and structurally similar compounds were determined in white snakeroot and rayless goldenrod before and after various drying conditions. Tremetone, dehydrotremetone, and structurally similar compounds in rayless goldenrod and white snakeroot are most stable upon freeze-drying, followed by air-drying, and least stable upon oven-drying (60 °C). Also demonstrated is that tremetone is stable and that dried white snakeroot and rayless goldenrod are capable of inducing toxicosis in livestock.     

Metabolism and distribution of [2,3-(14)C]acrolein in lactating goats

The metabolism and distribution of [2,3-(14)C]acrolein were studied in a lactating goat orally administered 0.82 mg/kg of body weight/day for 5 days. Milk, urine, feces, and expired air were collected. The goat was killed 12 h after the last dose, and edible tissues were collected. The nature of the radioactive residues was determined in milk and tissues. All of the identified metabolites were the result of the incorporation of acrolein into the normal, natural products of intermediary metabolism. There was evidence that the three-carbon unit of acrolein was incorporated intact into glucose, and subsequently lactose, and into glycerol. In the case of other natural products, the incorporation of radioactivity appeared to result from the metabolism of acrolein to smaller molecules followed by incorporation of these metabolites into the normal biosynthetic pathways.     

Modelling mammalian extinction and forecasting recovery: koalas at Iluka (NSW, Australia)

This study investigated the recent demise of a koala population at Iluka in eastern Australia and demonstrates the potential role of population viability analysis (PVA) in the recovery and management of similar small populations. Information about the Iluka population was reconstructed from various sources, including community knowledge, wildlife carer data, and from a radiotracking program. Modelling scenarios were constructed to identify which factors may be critical to the survival of the Iluka population and which management options could provide the most effective means of its recovery. The model suggested that even substantial improvements in mortality and fertility alone do not prevent the modelled population declining towards extinction. Rebuilding of the koala population is likely to require guaranteed regular immigration of animals of both sexes in conjunction with considerable improvements in population mortality and fertility. This highlights the importance of the metapopulation for recruitment, an outcome that was not expected prior to modelling. These modelling outcomes suggest that the management of small, local populations of koalas will need a concerted management effort focusing on multiple causes of population change. Local management actions, such as reducing road deaths and managing habitat and fire, must be accompanied by knowledge of the larger geographical population.     

Enantiomeric synthesis of (S)-2-methylbutanoic acid methyl ester, apple flavor, using lipases in organic solvent

Enantiomeric selective synthesis of (S)-2-methylbutanoic acid methyl ester, which is known as a major apple and strawberry flavor, was performed from racemic 2-methylbutanoic acid using lipases in organic solvent. Among 20 lipases, lipase IM 20 (immobilized lipase of Rhizomucor miehei), lipase AP (Aspergillus niger), and lipase FAP-15 (Aspergillus javanicus) exhibited higher enzymatic activities and enantioselectivities and were selected for the synthesis of (S)-2-methylbutanoic acid methyl ester. Using these enzymes, the reaction conditions such as temperature and lyophilizing pH were optimized, and kinetic parameters were determined. All of the reactions were performed in isooctane, which was identified as the best reaction media for nonaqueous systems. At 20 degrees C maximum enantiomeric excess was observed, while synthetic activity increased as the temperature increased. Only lipases lyophilized at pH 5.5, 6. 0, 6.5, and 7.0 showed synthetic activity. In this pH range, enantioselectivities were not influenced by the lyophilizing pH. The K(M,S) and K(M,R) values for ester synthetic activity of lipase were 1120 and 1240 mM, respectively. Enzyme activity was inhibited by (S)-2-methylbutanoic amide, and its K(i) was calculated as 84 mM. (S)-2-Methylbutanoic amide acted as a competitive inhibitor.     

Absorption, disposition, metabolism, and excretion of [3-(14)C]caffeic acid in rats

Male Sprague-Dawley rats ingested 140 × 10(6) dpm of [3-(14)C]trans-caffeic acid, and over the ensuing 72 h period, body tissues, plasma, urine, and feces were collected and the overall levels of radioactivity determined. Where sufficient radioactivity had accumulated, samples were analyzed by HPLC with online radioactivity and tandem mass spectrometric detection. Nine labeled compounds were identified, the substrate and its cis isomer, 3'-O- and 4'-O-sulfates and glucuronides of caffeic acid, 4'-O-sulfates and glucuronides of ferulic acid, and isoferulic acid-4'-O-sulfate. Four unidentified metabolites were also detected. After passing down the gastrointestinal tract, the majority of the radiolabeled metabolites were excreted in urine with minimal accumulation in plasma. Only relatively small amounts of an unidentified (14)C-labeled metabolite were expelled in feces. There was little or no accumulation of radioactivity in body tissues, including the brain. The overall recovery of radioactivity 72 h after ingestion of [3-(14)C]caffeic acid was ～80% of intake.     

Population recovery of the threatened endemic Rodrigues fody (Foudia flavicans) (Aves, Ploceidae) following reforestation

In 1999, we intensively surveyed all suitable habitat on the Mascarene Island of Rodrigues and mapped 334 territories of the threatened endemic Rodrigues fody (Foudia flavicans). In addition, we recorded 58 unpaired males, 85 juveniles, and 100 grey-brown-plumaged birds, for a minimum estimated population size of 911 birds. This represents a near 100-fold increase in population size since 1968, which has been achieved in the absence of translocation or taxon-specific management. Birds were generally distributed in direct proportion to the availability of various forest types, but relatively more birds were found in mature, dense forests. Fody density at 10 selected sites, where vegetation surveys were carried out, increased significantly with increasing tree height, canopy cover and tree species diversity. This suggests that habitat management aimed at enhancing Rodrigues fody populations should focus on the protection of existing wooded valleys to allow forest maturation and expansion of afforested areas.     

The effects of feral goats (Capra hircus) on island ecosystems

Feral goats (Capra hircus) are implicated in habitat destruction, and alteration of species composition on sensitive insular ecosystems. In the absence of population control, goats have become the ecologically dominant species on many islands with the results that numerous endemic plant species have been extirpated, or are threatened by excessive grazing. It is demonstrated that removal of goats can lead to rapid recovery of suppressed vegetation. The problems associated with excessive numbers of feral goats have rarely been studied or formally recognised. Extensive and intensive research is critically needed if affected island ecosystem are to be preserved or restored.     

Misidentification of soil bacteria by fatty acid methyl ester (FAME) and BIOLOG analyses

 Fatty acid methyl ester (FAME) analysis is commonly used by soil scientists as a sole method for identifying soil bacteria. We observed discrepancies with this method for identifying certain species of bacteria. Therefore, we used carbon substrate oxidation patterns (BIOLOG) and some simple physical and chemical tests to determine the extent of these discrepancies. Identification with FAME profiles gave false positives for Arthrobacter globiformis, Micrococcus kristinae, and M. luteus, and identification with BIOLOG patterns gave a false positive identification for A. globiformis. A visual check and Gram stain are recommended when FAME analysis identifies soil isolates as M. kristinae or M. luteus, and an additional spore formation test is recommended when FAME and BIOLOG analyses identify isolates as A. globiformis. Received: 14 January 2000     

Land use changes the soil carbon stocks,microbial biomass and fatty acid methyl ester (FAME) in Brazilian semiarid area

Land use affect soil C and microbial structure, especially in tropical dry areas. The objective of this study was to evaluate the effects of the land use on physical, chemical, and microbiological attributes of soils from Brazilian semiarid. We analyzed soil physical, chemical, total carbon stocks (TCS), water-soluble carbon (WSC), microbial biomass carbon (MBC) and microbial structure of soil from forest, no irrigation maize, succession areas (Anadenanthera falcate and Tabebuia alba) and secondary shrubby vegetation. The use of soil influences C stock. The forest soil showed higher TCS and MBC. The conversion in T. alba reduced in 9% soil total bacteria. The multivariate analysis showed that TCS, MBC and FAMEs contributed to separation of natural forest and other areas in the superficial layer. This study indicates that the conversion of forest into successional areas can decrease by up to 44% TCS and 68% MBC. The present study provided alarming data concerning the impact of land use on quality of soil in a tropical dry region in Northeastern Brazil. Our results provide an alternative tool for the management of deforested dry areas that could serve as guideline for management plan to sustainability for agricultural impacted dry areas.     

Enhancement of polyphenol recovery from rosemary (Rosmarinus officinalis) and sage (Salvia officinalis) by enzyme-assisted ensiling (ENLAC).

The efficacy of enzyme-assisted ensiling (ENLAC) in the recovery of polyphenols from rosemary and sage was tested. Fresh rosemary and sage were chopped and ensiled in 0.5-L anaerobic jars. Treatments comprised control (no additives), 0.5% glucose and lactic acid bacteria, and 1% cellulase plus 1% hemicellulase plus pectinase. Following storage at room temperature for 45 days (experiment 1) and 26 days (experiment 2), polyphenols were extracted from the silages in ethanol either by direct blending or by cold extraction. The enzyme treatment resulted in silages with the lowest pH values, lowest fiber content, highest water-soluble sugar content, and highest polyphenol recovery; this treatment resulted in increased polyphenol recovery from rosemary and sage, by 100 and 20%, respectively. Comparison between direct blending and cold extraction revealed similar efficiency of polyphenol recovery.     

Microbial metabolism in reduction process of paddy soils (Part 2)

The previous experiences^1-3) with incubation experiments of the soils under submargd condition indicated that the disappearance of molecular oxygen and nitrates occurred shortly after sub-emerging, and then the reduction of ferric iron proceeded, being followed by the reduction of sulfates and the formation of methane which nre caused by the activities of strict anaerobes. It was suggested from the above fact that the reduction process in the submarged soils was affected mainly by two factors: namely, the amount of reducible ferric iron and the soil organic matters which are avaiable as substrate for microbial metabolism.     

Ammonium (15N) metabolism in cotton under salt stress

Plant growth and metabolism is impaired under stress conditions, resulting in decreased crop yields. The purpose of this investigation was to evaluate the NaCl stress effects on NH⁺ ₄ metabolism in cotton plants at vegetative and reproductive stages of growth.

Cotton (Gossypium hirsutum L.) plants grown in normal (control) and NaCl treated Hoagland solutions were analyzed for distribution of N¹⁵ in NH⁺ ₄ plus amide‐N, free α‐amino‐N, total soluble‐N and protein‐N after the plants were provided ¹⁵NH₄NO₃ in nutrient solutions for 6, 12 and 24 h. The concentration of protein‐¹⁵N was enhanced under a low level of NaCl (‐0.4 MPa osmotic potential) at the vegetative growth stage. The difference between the protein‐¹⁵N concentration of the moderately salinized (‐0.8 MPa) plants and the controls was not significant. A high level of NaCl (‐1.2 MPa) significantly decreased protein‐N content of plants compared with the controls and any other level of salinity. The NaCl increased accumulation of NH₄ ⁺ plus amide‐N, free (α‐amino‐N, and total soluble‐N in cotton shoots, at both stages of growth. Low osmotic potential (high osmotic pressure) of the nutrient solution induced by excessive amounts of NaCl in nutrient solution inhibited NH⁺ ₄ metabolism and decreased protein synthesis, thus resulting in accumulation of soluble N‐compounds. The ionic effect probably contributed also to inhibition of protein synthesis.     

Identification of pinnatoxins and discovery of their fatty acid ester metabolites in mussels ( Mytilus edulis ) from eastern Canada

Pinnatoxins are a group of fast-acting cyclic imine toxins previously identified in shellfish from Asia, the southern Pacific, and northern Europe. In this work pinnatoxins were detected in mussels from locations across the eastern coast of Canada. Pinnatoxin G (6) was the major structural variant present, sometimes at levels >80 μg/kg, whereas much lower levels of pinnatoxin A (1) were detected in some samples. Increased concentrations were observed following base hydrolysis of extracts, leading to the discovery by LC-MS of a range of fatty acid esters of 6. Information on the structures of these acylated derivatives was provided through a series of mass spectrometric experiments, supported by partial synthesis, and it is proposed that the compounds are 28-O-acyl esters of 6. Although acyl esters of a range of other phycotoxins are known to form as metabolites in shellfish, this is the first report of their existence for this particular toxin class. The occurrence of pinnatoxins in North American shellfish further highlights the international distribution of these toxins.     

Novel trisaccharide fatty acid ester identified from the fruits of Morinda citrifolia (Noni)

Two known glycosides and a novel trisaccharide fatty acid ester were isolated from the n-butanol-soluble fraction of the fruits of Morinda citrifolia (noni). Structure determination was carried out by spectral techniques such as MS, IR, NMR, and 2D-NMR. The novel trisaccharide fatty acid ester was elucidated as 2, 6-di-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose. The known compounds were identified as rutin and asperulosidic acid.