Production and Purification of d-Aminoacylase from Alcaligenes denitrificans and Taxonomic Study of the Strain

A d-aminoacylase-producing microorganism, strain DA181, isolated from soil was identified as Alcaligenes denitrificans subsp. denitrificans. This strain produced about 29,300 units (micromoles of product formed per hour) of d-aminoacylase and 2,300 units of l-aminoacylase per gram of cells (wet weight) when cultivated in a medium containing 1% N-acetyl-dl-leucine as the carbon source. The d-aminoacylase was purified 345-fold. The specific activity of the purified enzyme was 108,600 units per mg of protein when N-acetyl-d-methionine was used as a substrate. The apparent molecular weight was 58,000, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N-Acetyl-d-methionine was the favored substrate, followed by N-acetyl-d-phenylalanine. This enzyme had a high stereospecificity, and its hydrolysis of N-acetyl-l-amino acids was almost negligible.     

Discrimination of alfalfa weevil strains by allozyme analysis

Allozyme profiles of eastern weevils (Beltsville, Maryland; Washington Co., Illinois), western weevils (Logan and St. George, Utah), and Egyptian weevils (Yuma, Arizona; Westmorland, California) were compiled by acrylamide gel electrophoresis. Twenty-two gene loci from 12 enzymes (ACPH, ADH, AMY, AO, EST, GOT, G-6PDH, MDH, ME, SOD, TYR, XDH) were analyzed. Mean heterozygosity of these populations was 0.231, with an average proportion of polymorphic loci of 0.536. The mean genetic distance of all weevil populations was 0.033 and the fixation index was 0.024. Diagnostic loci were found which could distinguish western weevils from eastern and Egyptian weevils. The small genetic distance between the eastern and Egyptian weevils suggests that they may be the same strain and are certainly different from the western weevil strain. Based on this and other evidence, we conclude that all weevil strains in the United States are Hypera postica (Gyllenhal), and that the use of H. brunneipennis (Boheman) for the Egyptian alfalfa weevil of North America should be discontinued.

---

Résumé Les allozymes d'Hypera de l'est des USA (Beltsville, Maryland; Washington Co., Illinois), de l'ouest des USA (Logan et St Georges, Utah) et égyptiens (Yuma, Arizona; Westmorland, Californie) ont été analysés par électrophorèse sur gel d'acrylamide. L'étude a porté sur 22 loci de 12 enzymes (ACPH, ADH, AMY, AO, EST, GOT, G-6PDH, MDH, ME, SOD, TYR, XDH). L'hétérozygotie moyenne de la population était 0.231, avec une moyenne de loci polymorphes de 0.536. La distance génétique moyenne de l'ensemble des populations était de 0.033 et l'indice de fixation de 0.024. Des loci caractéristiques ont été trouvés qui pourraient permettre de distinguer les Hypera occidentaux des orientaux et des égyptiens. La faible distance génétique entre les Hypera orientaux et égyptiens suggère qu'ils appartiennent à la même souche et sont certainement différents des occidentaux. A partir de cela et d'autres éléments, nous concluons que tous les Hypera des USA sont H. postica Gyllenhal et que l'utilisation d'H. brunneipennis Boheman pour désigner les Hypera égyptiens d'Amérique du Nord doit être abandonnée.

     

Inheritance of a vestigial wing mutation in the alfalfa weevil, Hypera postica

Alfalfa weevils (Hypera postica (Gyllenhal)) with vestigial hind wings were discovered in a population from Wageningen, the Netherlands, and two populations from the United States—an eastern weevil strain from Beltsville, Maryland and an Egyptian weevil strain from Atascadero, California. Such a mutant was absent from 23 other populations surveyed in the United States—three from eastern, seven from western, and 13 from Egyptian weevil strains. This mutation is due to a dominant autosomal gene with normal-wing individuals as recessive. The mutant gene can be transferred from eastern weevil to the western weevil strain. The short-wing trait may be useful for genetic manipulation to control the alfalfa weevil.

---

Résumé Des H. postica aux ailes postérieures vestigiales ont été découverts dans une population de Wageningen (Pays Bas) et deux des USA—une lignée orientale de Beltsville (Maryland) et une lignée de H. brunneipennis d'Atascadero (Californie). Ce mutant était absent de 23 autres populations examinées aux USA: 3 de l'est, 7 de l'ouest et 13 de H. brunneipennis. Cette mutation est due à un gène dominant antosomal avec aile normale comme récessif. Le gêne mutant peut être transféré des lignées orientales aux lignées occidentales. Le caractère aile courte peut être pratique pour les manipulations génétiques destinées à maîtriser les populations d'H. postica.

     

Temperature control of germination and its possible role in the survival of a non-dormant population of Avena fatua

Germination of freshly harvested seeds of a non-dormant (ND) line (Stonehouse 319) of wild oats ( Avena fatua L.) was inhibited by incubation of the seeds at relatively high temperatures of 25 and 30°C. The germination inhibition in these seeds appeared to be a case of thermo-inhibition which was the direct effect of hightemperature treatment (HIT), since it did not persist after transferring the seeds to an optimum germination temperature of 20°C. Even a prolonged HTT of 30°C for over 5 weeks did not prevent germination of about 80% of the seeds transferred to 20°C. However, in a significant proportion of the seeds, thermo-dormancy was induced by 10 days of HTT at 30°C if the seeds were then incubated at sub-optimal temperatures of 5 to 15°C. This thermo-dormancy would appear to be 'restrictive' in form, since its expression was restricted to very specific conditions. Relatively low inclubation temperaturs of 5 and 10°C markedly slowed germination whether HTT was applied or not. The results suggest that thermo-inhibition and thermo-dormancy, induced during seasonal temperature fluctuations, may provide a survival mechanism for seeds of such ND lines as Stonehouse 319.     

Water and solute transport along developing maize roots

Hydraulic and osmotic properties were measured along developing maize (Zea mays L.) roots at distances between 15 and 465 mm from the root tip to quantify the effects of changes in root structure on the radial and longitudinal movement of water and solutes (ions). Root development generated regions of different hydraulic and osmotic properties. Close to the root tip, passive solute permeability (root permeability coefficient, P_sr) was high and selectivity (root reflection coefficient, _sr) low, indicative of an imperfect semipermeable root structure. Within the apical 100–150 mm, P_sr decreased by an order of magnitude and _sr increased significantly. Root hydraulic conductivity (Lp_r) depended on the nature of the force (hydrostatic and osmotic). Osmotic Lp_r was smaller by an order of magnitude than hydrostatic Lp_r and decreased with increasing distance from the root tip. Throughout the root, responses in turgor of cortical cells and late metaxylem to step changes in xylem pressure applied to the base of excised roots were measured at high spatial resolution. The resulting profiles of radial and longitudinal propagation of pressure showed that the endodermis had become the major hydraulic barrier in older parts of the root, i.e. at distances from the apex ä 150 mm. Other than at the endodermis, no significant radial hydraulic resistance could be detected. The results permit a detailed analysis of the root's composite structure which is important for its function in collecting and translocating water and nutrients.Abbreviations and Symbols CPP cell pressure probe - IT root segments with intact tips; - Lp_r root hydraulic conductivity - Lp_rh hydrostatic hydraulic conductivity of root - Lp_ro osmotic hydraulic conductivity of root - P_app hydrostatic pressure applied to cut end of root - P_c cell turgor - P_{c, cor} turgor of cortical cell - P_c,xyl turgor of late metaxylem vessel - P_ro stationary root pressure - P_r0,seal stationary root pressure of sealed root segment - P_sr solute permeability coefficient of root - RPP root pressure probe - TR root segments with tip removed - _sr reflection coefficient of root Dedicated to Professor Andreas Sievers on the occasion of his retirement     

Water reuse in the L-lysine fermentation process

L-Lysine is produced commercially by fermentation. As is typical for fermentation processes, a large amount of liquid waste is generated. To minimize the waste, which is mostly the broth effluent from the cation exchange column used for l-lysine recovery, we investigated a strategy of recycling a large fraction of this broth effluent to the subsequent fermentation. This was done on a labscale process with Corynebacterium glutamicum ATCC 21253 as the l-lysine-producing organism. Broth effluent from a fermentation in a defined medium was able to replace 75% of the water for the subsequent batch; this recycle ratio was maintained for three sequential batches without affecting cell mass and l-lysine production. Broth effluent was recycled at 50% recycle ratio in a fermentation in a complex medium containing beet molasses. The first recycle batch had an 8% lower final l-lysine level, but 8% higher maximum cell mass. In addition to reducing the volume of liquid waste, this recycle strategy has the additional advantage of utilizing the ammonium desorbed from the ion-exchange column as a nitrogen source in the recycle fermentation. The major problem of recycling the effluent from the complex medium was in the cation-exchange operation, where column capacity was 17% lower for the recycle batch. The loss of column capacity probably results from the buildup of cations competing with l-lysine for binding. (c) 1996 John Wiley & Sons, Inc.     

Compliance of chest wall in obese subjects

Whereas studies in awake subjects have demonstrated that chest wall compliance (Ccw) is low in obese subjects, the one study performed on paralyzed obese subject found Ccw to be normal. The purpose of this study was to measure Ccw in awake obese subjects with the pulse-flow technique, a method which appears to detect respiratory muscle relaxation. Seven normal males, 14 obese males, and 8 obese females [body mass index (BMI) varied from 20 to 83 kg/m2] were studied in the seated position. Ccw was measured by blowing air at a constant flow into the mouth and lungs for approximately 2 s and calculated by dividing airflow in liters per second by the change in esophageal minus body surface pressure in centimeters of water per second. In normal and obese subjects we found no correlation between BMI and Ccw. We conclude that obesity does not decrease Ccw.     

Simultaneous determination of molting and juvenile hormone titers of the greater wax moth

A simple and rapid extraction procedure was developed to determine simultaneously the molting hormone (MH) and juvenile hormone (JH) activity in a single insect tissue sample. From the onset of the last larval stage to adult eclosion of the greater wax moth, Galleria mellonella, three JH peaks were noted: at the time of the sixth larval ecdysis, 1 day before the seventh larval ecdysis, and at the time of adult eclosion. Three MH peaks were recorded for the male: at 1 day before the sixth larval ecdysis, 1 day before the seventh larval ecdysis, and 2 days after pupation. In the female, a fourth peak was shown at the time of adult eclosion. This fourth peak exhibits the highest molting hormone activity of all samples, 1600 Musca units/g of fresh tissue or an equivalent of 5.6 μg/g of ecdysterone. Eighty per cent of this MH accumulated in the ovary. The significance of MH and JH titers as related to the endocrine regulation of development is discussed in the light of this finding.