Influence of extremely low-frequency electric fields on the growth of Vigna radiata seedlings

The biological effects of extremely low-frequency electric fields (ELF) on living organisms have been explored in many studies, but the results are controversial and only a few studies investigated the influence of the intensity of the applied field on seedling growth. Here we assess the effects of a 50 Hz sinusoidal electric field on the early growth of Vigna radiata seedlings while varying the field intensity. Experiments performed in a dark, constant-climate chamber on several thousands of seedlings show that the field produces an inhibitory effect at a low field intensity and an enhancing one at a higher intensity. The maximum negative effect occurs at about 450 V/m, which is an intensity much lower than the exposure limits currently in force in the safety regulations.     

Application of computer to monitoring and control of fermentation process: Microbial conversion of ML-236B Na to pravastatin

An automatic feeding process for microbial hydroxylation of ML236B sodium salt (ML-236B Na; compactin) by Streptomyces carbophilus SANK 62585 was developed. The hydroxylated product, pravastatin sodium salt (pravastatin; trade name Mevalotin), is an inhibitor of 3-hydroxy-3-methyglutaryl-coenzyme A reductase (HMG-CoA reductase) used as cholesterol-lowering drug. The hydroxylation activity of S. carbophilus was induced by the addition of ML236B Na to culture broth but inhibited by high concentration of ML236B Na. In order to obtain high conversion yield, it was necessary to maintain optimum ML236B Na concentration throughout the fermentation by continuous feeding. For this purpose, we developed an on-line monitoring method, which mainly consisted of a cross-flow filtration module, high-performance liquid chromatography (HPLC) analyzer, feed pump, and microcomputer for regulation of ML236B Na concentration. An algorithm for control of ML236B Na feed rate based on feedback and feed-forward control where conversion rate after Deltat was estimated by using regression analysis of the five latest values of conversion rate. In a fed-batch culture employing this system, the concentration of ML236B Na was maintained at optimum level during the fermentation and the productivity of pravastatin was increased threefold over that obtained in manual control culture. (c) 1993 John Wiley & Sons, Inc.     

Alginate embedding and subsequent sporulation of in vitro-produced Conidiobolus thromboides hyphae using a pressurised air-extrusion method

Conidiobolus thromboides is an entomophthoralean fungus with potential as a biological control agent of aphids. However, its application in biological control is limited due to its formulation requirements. The objective of this study was to develop and optimise a novel air-extrusion method to embed C. thromboides hyphae at high density in alginate pellets. An orthogonal experimental design was used to investigate selected combinations of parameters known to affect hyphal density within pellets. The diameter of pellets produced, and the calculated density of hyphae within them, ranged from 0.18 ± 0.09 to 3.17 ± 0.06 mm and from 0.02 to 350.56 mg/mm³ respectively. These data were used to predict the optimal parameter combination to deliver the greatest density of hyphae of C. thromboides per pellet: 1% sodium alginate, a 1:2 ratio of hyphae to sodium alginate, an orifice diameter of 0.232 mm and an air pressure of 0.05 MPa. Pellets made under the optimal conditions predicted produced a mean total of 4.3 ± 0.6 × 10⁵ conidia per pellet at 100% relative humidity which was significantly greater than the mean total number of conidia produced from infected aphid cadavers of comparable size (9.35 ± 0.85 × 10⁴) (p < 0.001). In conclusion, air-extrusion embedding appears to be a promising method for formulating in vitro-produced hyphae of C. thromboides for use in biological control.     

Synthesis and analytics of 2,2,3,4,4-d5-19-nor-5alpha-androsterone--an internal standard in doping analysis

A short and efficient synthesis of pentadeuterated 2,2,3,4,4-d5-19-nor-5alpha-androsterone 7 starting from 19-norandrost-4-ene-3,17-dione 1 by a d1-L-Selectride mediated stereo- and regioselective reduction of the 3-keto group is presented. The use of compound 7 as internal standard for the detection of anabolic steroids via mass spectrometric techniques such as gas chromatography-mass spectrometry (GC-MS) is discussed.     

Development of a competitive immunoassay for the determination of N-(2-hydroxypropyl)valine adducts in human haemoglobin and its application in biological monitoring

Abstract

Propylene oxide (PO) is an important industrial compound and a directly acting mutagen. Human exposure to PO can be monitored by the determination of haemoglobin adducts. An immunoassay that quantifies the N-terminal adduct N-(2-hydroxypropyl)valine in whole haemoglobin was developed and its potential usefulness as a tool for biologically monitoring occupational exposure was demonstrated. Analytical reliability was confirmed in a comparative study with GC-MS (range 3.7–992 nmol g^?1 haemoglobin (Hb), correlation coefficient 0.99, n=10). The assay has been configured as a competitive enzyme-linked immunosorbent assay to facilitate the rapid throughput of samples. The assay employs a whole blood matrix and has a working range of 2–250 pmol g^?1 Hb. It does not appear to be affected by structurally similar metabolites and has been used to determine adducts in human blood samples. The first results in potentially exposed workers indicate the assay's high potential usefulness in routine occupational biomonitoring of exposure to PO.     

Development of a competitive immunoassay for the determination of N-(2-hydroxyethyl)valine adducts in human haemoglobin and its application in biological monitoring

Ethylene oxide (EO) is an important industrial compound and a directly acting mutagen. Human exposure to it can be monitored by the determination of haemoglobin (Hb) adducts. An immunoassay that quantifies the N-terminal adduct N-(2-hydroxyethyl)valine in whole blood was developed and its potential usefulness as a tool for biologically monitoring occupational exposure demonstrated. Analytical reliability was confirmed in a comparative study with gas chromatography-mass spectrometry (range 0.040-589 nmol g^-1 Hb, correlation coefficient 0.98, n=10). The assay was configured as a competitive enzyme-linked immunosorbent assay to facilitate the rapid throughput of samples. The assay uses a whole blood matrix and has a working range of 10-10 000 pmol N-(2-hydroxethyl)valine g^-1 Hb. The assay does not appear to be affected by structurally similar metabolites and has been used to determine adducts in human blood samples. The first results from potentially exposed workers indicate the assay might be a powerful tool for the routine occupational biomonitoring of EO exposure.     

沙棘对中国亚湿润干旱区的杨树人工林养分分布及生物循环影响

通过将沙棘（ＨｉｐｐｏｐｈａｅｒｈａｍｎｏｉｄｅｓＬ．）与三种杨树品种（小黑杨（Ｐｏｐｕｌｕｓ‘Ｘｉａｏｈｅｉ’）昭林６号杨（Ｐ．‘Ｚａｏｌｉｎ０６’）和欧美杨６４号（Ｐ．ｅｕｒａｍｅｒｉｃａｎｅｃｖ．‘Ｎ３０１６’）的人工林分别按株混和行混两种方式进行混交实验,研究了固氮植物沙棘对亚湿润干旱区的杨树人工林养分分布和循环的影响,连续３ａ的观测研究得以下结果,沙棘叶片的氮,磷和钾的元素粪土了高于杨树     

A high incidence of parasitism ofHeliothis SPP. [Lep.: Noctuidae] larvae in cotton in Southeastern Arkansas

During 1981 and 1982, bollworm,Heliothis zea (Boddie), and tobacco budworm,H. virescens (F.), larvae (n=3,666) were collected from 41 cotton fields near Portland, Arkansas (USA) to assess the occurrence of parasitism. Three strategies were employed to controlHeliothis spp. in these fields: (1) release ofTrichogramma pretiosum Riley; (2) insecticidal control; or (3) inaction (check). Insecticide use in nonchemical control fields was reduced, but not eliminated.Heliothis spp. larvae collected in cotton had higher parasitism rates in 1981 (30.9%) and 1982 (50.1%) than had been reported for cotton since the advent of organochlorine insecticide usage. Four species of larval parasites and 1 species of larval-pupal parasite were recorded. The larval parasiteMicroplitis croceipes (Cresson) comprised 90.6% and 94.5% of all parasitic insects reared from field collectedHeliothis spp. in 1981 and 1982, respectively. No difference (P>0.05) in level of parasitism existed betweenH. zea andH. virescens. Differences between treatments occurred only in 1982 whenH. zea larvae were parasitized at a greater (P<0.05) rate in check fields (68.3%) than in insecticidal control fields (44.3%). Higher levels of larval parasitism in cotton fields may be a consequence of reduced insecticide usage and changes in materials applied, particularly the pyrethroids. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Dept. of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.