Soil amidase activity in polyacrylamide-treated soils and potential activity toward common amide-containing pesticides

 Polyacrylamide (PAM) is currently used as an irrigation water additive to significantly reduce the amount of soil erosion that occurs during furrow irrigation of crops. Elevated soil amidase activity specific toward the large PAM polymer has been reported in PAM-treated field soils; the substrate specificity of the induced amidase is uncertain. PAM-treated and untreated soils were assayed for their capacity to hydrolyze the amide bond in carbaryl (Sevin), diphenamid (Dymid), and naphthalene acetamide. Based on results obtained with a soil amidase assay, there was no difference between PAM-treated and untreated soils with respect to the rate of amide bond hydrolysis of any of the agrochemicals tested. It appears that under these assay conditions the PAM-induced soil amidase is not active toward the amide bonds within these molecules. However, carbaryl was hydrolyzed by a different soil amidase. To our knowledge, this is the first soil enzyme assay-based demonstration of the hydrolysis of carbaryl by a soil amidase. Received: 23 June 1999     

The bionomics ofLiriomyza Trifolii on Gypsophila and Bean Leaves

A study was carried out to determine the distribution of feeding and oviposition punctures made byLiriomyza trifolii Burgess on gypsophila(Gypsophila paniculata ) and bean(Phaseolus vulgaris) leaves, and the development times of the immature stages on these plants. The absolute number of punctures per leaf area was much greater on bean leaves than on gypsophila leaves. The number of mines per leaf was also higher on beans than on gypsophila, but the ratio of mines/punctures was higher on gypsophila. Gypsophila leaves were punctured on both sides, but most of the punctures were on the distal third of the upper leaf side. On beans the punctures were dispersed uniformly on the upper side of the leaf. The larval period (±SE) at temperatures of 20, 25 and 30°C was 9.9±0.2, 4.4±0.1 and 3.7±0.1, and 5.5±O. l, 3.7±0.1 and 2.4±0.1 days, on gypsophila and bean, respectively. The pupal period at 17, 20, 25 and 30°C lasted 19.9±0.2, 14.7±0.1, 10.4±0.1 and 7.8±0.1 days, respectively.     

Patterns of Variation in Alkamides and Cichoric Acid in Roots and Aboveground Parts of Echinacea purpurea (L.) Moench

We investigated patterns of variation in alkamides and cichoric acid accumulation in the roots and aboveground parts of Echinacea purpurea (L.) Moench. These phytochemicals were extracted from fresh plant parts with 60% ethanol and quantified by high performance liquid chromatography (HPLC) analysis. Concentrations of alkamides and cichoric acid were measured on a dry-weight basis (mg·g(-1)). For total alkamides, concentrations among individual plants varied from 5.02 to 27.67 (mean = 14.4%) in roots, from 0.62 to 3.42 (mean = 1.54) in nearly matured seed heads (NMSH), and 0.22 to 5.25 (mean = 0.77) in young tops (about ? flower heads, ? leaves, and ? stems). For cichoric acid, concentrations among individual plants varied from 2.65 to 37.52 (mean = 8.95), from 2.03 to 31.58 (mean = 10.9), and from 4.79 to 38.55 (mean = 18.88) in the roots, the NMSH, and the tops, respectively. Dodeca-2E, 4E, 8Z, 10E-tetraenoic acid isobutylamide and dodeca-2E, 4E, 8Z, 10Z-tetraenoic acid isobutylamide (alkamides 8/9) accounted for only 9.4% of the total alkamides in roots, but comprised 87.9% in the NMSH, and 76.6% in the young tops. Correlations of concentrations of alkamides or cichoric acid between those of roots and those of the NMSH were not statistically significant, and either within the roots, the NMSH, and the young tops. However, a significant negative correlation was observed between the concentration of cichoric acid in the roots and in young tops, and a significant positive correlation was observed between total alkamide concentration in the roots and cichoric acid concentration in the young tops. These results may be useful in the genetic improvement of E. purpurea for medicinal use.     

Commercial Seed Lots Exhibit Reduced Seed Dormancy in Comparison to Wild Seed Lots of Echinacea purpurea

Seed germination patterns were studied in E. purpurea (L.) Moench grouped by seed source, one group of seven lots from commercially cultivated populations and a second group of nine lots regenerated from ex situ conserved wild populations. Germination tests were conducted in a growth chamber in light (40 μmol·m(-2)·s(-1)) or darkness at 25 °C for 20 days after soaking the seeds in water for 10 minutes. Except for two seed lots from wild populations, better germination was observed for commercially cultivated populations in light (90% mean among seed lots, ranging from 82% to 95%) and in darkness (88% mean among seed lots, ranging from 82% to 97%) than for wild populations in light (56% mean among seed lots, ranging from 9% to 92%) or in darkness (37% mean among seed lots, ranging from 4% to 78%). No germination difference was measured between treatments in light and darkness in the commercially cultivated populations, but significant differences were noted for treatments among wild populations. These results suggest that repeated cycles of sowing seeds during cultivation without treatments for dormancy release resulted in reduced seed dormancy in E. purpurea.     

Resident lymphocytes in the epidermis and adnexal epithelia of normal dorsolateral thorax of alpacas

A small population of resident T-lymphocytes is present in the normal epidermis of skin from humans, mice, sheep, and cattle. The objective of this study was to determine the prevalence of lymphocytes, CD3+ cells (T-lymphocytes) and CD79a+ cells (B-lymphocytes and plasma cells), in the epidermis and adnexal epithelia of alpacas. Skin-biopsy specimens from the normal skin of the dorsolateral thorax of 31 alpacas were examined histologically and immunohistochemically for the presence of CD3+ cells and CD79a+ cells in the epidermis and adnexal epithelia. CD3+ T-lymphocytes, but not CD79a+ cells, were present in the epidermis and adnexal epithelia. Therefore, in the absence of other signs of inflammation, the presence of lymphocytes in these structures in skin-biopsy specimens should be considered normal.     

Modulation of hepatic drug metabolizing enzymes and oxidative status by rooibos (Aspalathus linearis) and Honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas in rats

Rooibos and honeybush teas significantly (P < 0.05) enhanced the activity of cytosolic glutathione S-transferase alpha. A significant (P < 0.05) to marginal (P < 0.1) increase in the activity of the microsomal UDP-glucuronosyl transferase was obtained with unprocessed rooibos and honeybush teas, respectively. Oxidized glutathione (GSSG) levels were significantly (P < 0.05) reduced in the liver of all tea treated rats while reduced glutathione (GSH) was markedly increased in the liver of the herbal tea treated rats. These changes resulted in a significant (P < 0.05) increase in the GSH/GSSG ratio by the unprocessed, processed rooibos and unprocessed honeybush teas. Green and black teas markedly to significantly decreased the oxygen radical absorbance capacity in liver homogenates, respectively. Modulation of phase II drug metabolizing enzymes and oxidative status in the liver may be important events in the protection against adverse effects related to mutagenesis and oxidative damage.     

Mechanisms of arsenite elimination by Thiomonas sp. isolated from Carnoulès acid mine drainage

Weathering of the arsenopyrite-rich tailings of the Carnoulès abandoned mining site (Gard, France) results in the formation of acid mine waters heavily loaded with arsenic. Dissolved arsenic present in the seepage waters is precipitated within a few meters from the bottom of the tailing dam by microorganisms. From these effluents, we have isolated and characterized a Gram negative bacterium involved in this bioremediation process. This bacterium, which belongs to the Thiomonas genus, is very efficient in removing arsenite from contaminated acidic waters by oxidizing it to arsenate, which precipitates.     

RESEARCH ON REARING TURBOT (Scophthalmus maximus): RESULTS AND PERSPECTIVES

At the Centre Océanologique de Bretagne, a research program on turbot rearing has been in progress for several years. The life cycle is now under control. Up to 10,000 3-month-old juveniles can be produced per natural or shifted spawning season. Attention is now focused on the first week stages. Obtaining an average survival of 10% from hatching up to 3 months is still difficult. Weaning generally starts in 30-day-old larvae (75 mg wet weight) and the gross mortality during weaning is near 50%. Three-month-old juveniles weigh about 2 g. In Brittany, culture necessarily begins in a nursery using heated water. The grow-out period begins between 5 and 20 g: 5 g when winter is over, 20 g when winter is coming. At this stage they can grow either in tanks or in floating sea-cages and they may be fed dry pellets. After 20 g, moist foods containing at least 25%, on dry basis, of trashed fish are more efficient. Pure trashed fish also gives good results. The food conversion ratio is about 1 (dry food weight/wet weight fish gain). The first data on turbot growth in intensive conditions are encouraging. In our area, annual temperature of the open sea ranges from 7 to 18°C allowing an average weight gain of 1 kg at 2 years and 2 kg (3 kg in the best case) at 3 years of age. Control of spawning season is still necessary to obtain a good market size of about 2 kg of body weight in less than 3 years.