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排序方式: 共有746条查询结果,搜索用时 15 毫秒
1.
Summary Optimised procedures for the production and recovery of lipase at 25 litre scale by submerged fermentation using aRhizopus species isolated from petroleum-soaked soil are developed. These lipase preparations are characterized by dual pH optima (4.0 and 8.0), wide temperature optima (over 80% activity between 40–57°C), broad specificity for substrates, high degree of tolerance for common salts and excellent stability during usage as well as storage. 相似文献
2.
G Singh M M Singh S C Maitra W Elger V Kalra S N Upadhyay S R Chowdhury V P Kamboj 《Journal of reproduction and fertility》1988,83(1):73-83
RU-38486 or ZK-98734 treatment (3 mg/day, s.c.) to intact or hysterectomized adult female rats on Days 5-7 post coitum induced changes characteristic of luteolysis. Ultrastructurally, the luteal cells exhibited an extensive vacuolization of the cytoplasm and perinuclear areas, degeneration of mitochondrial cristae, massive accumulation of lipid droplets, increase in number of lysosome like granules and heterochromatinization of the nucleus. In general, RU-38486 induced more marked degeneration of the luteal cells than did ZK-98734. There was also a significant decrease in peripheral plasma progesterone concentrations in treated rats. We suggest that these antiprogestagens act via inhibition of luteal function in addition to their antagonism at the uterine progesterone receptor level. 相似文献
3.
Changes in activity levels of important enzymes of carbohydratemetabolism (and ß-amylases, sucrose synthetase, acidinvertase, acid phosphatase, glucose phosphate isomerase, aldolase,phosphofructokinase and pyruvate kinase) during seed developmentwere determined. Changes in the activities of these enzymesand their functional significance in developing seeds are described.A close correlation was found between the stage of maximum carbohydrateoxidation and the accumulation of reserve materials in the developingseeds.
1Present address: School of Agriculture and Forestry, Universityof Melbourne, Parkvilie 3052, Victoria, Australia.
2Present address: School of Botany, University of Melbourne,Parkville 3052, Victoria, Australia. (Received October 8, 1982; Accepted January 10, 1983) 相似文献
4.
Summary Gibberellins A3, A4+7 and A13 and (–)-kaurene delay floral-bud initiation and flowering and decrease the number of floral-buds and flowers in Impatiens balsamina under 4-hr photoperiods. They do not have any marked effect under 8-hr photoperiods. Under 16- and 24-hr photoperiods they hasten floral-bud initiation and flowering and increase the number of flowers, the effect being greater under 16- than under 24-hr days and the order of effectiveness being GA4+7>GA3>GA13>(–)-kaurene.While GA3 and GA4+7 promote extension growth, the effect being greater with the former, GA13 and (–)-kaurene do not promote it under any photoperiod. The magnitude of stem elongation in different treatments prior to floral-bud initiation increases from 4- to 8-hr photoperiods but decreases under 16- and 24-hr periods, the effect being more under 24-hr although both 16-and 24-hr photoperiods are noninductive for flowering. 相似文献
5.
6.
Fred J. Genthner Janeshwar Upadhyay Robert P. Campbell Barbara R. Sharak Genthner 《Microbial ecology》1990,20(1):283-288
Culturable counts of antibiotic resistant, genetically engineeredPseudomonas fluorescens were determined on antibiotic-containing plate count agar during starvation in water. Prior to starvation, colony counts
obtained on all media separated into two groups. The mean of the colony counts on plate count agar with or without tetracycline
(4.9 × 106 ml−1) was significantly higher than the mean colony counts on plate count agar containing either nalidixic acid or nalidixic acid
plus tetraclycline (2.5×106 ml−1). After 20 days of starvation the highest mean colony counts continued to be obtained on plate count agar (7.2 × 106 ml−1) with slightly, but significantly, lower counts obtained on plate count agar containing either nalidixic acid (5.6 × 106 ml−1) or tetraclycline (1.5×106 ml−1). A combination of nalidixic acid and tetracycline in plate count agar, however, dramatically reduced colony counts (8.3
× 102 ml−1) after this starvation period. The addition of catalase to plate count agar containing nalidixic acid and tetracycline negated
the effect caused by this combination of antibiotics. When colony counts obtained over the entire 20 day incubation were considered,
the addition of MgSO4 to plate count agar containing nalidixic acid and tetracycline resulted in a significant increase in colony counts. Other
combinations of antibiotics, nalidixic acid+carbenicillin, nalidixic acid+kanamycin, streptomycin+tetracycline, streptomycin+carbenicillin,
rifampicin+tetracycline, rifampicin+carbenicillin, and rifampicin+kanamycin, did not inhibit colony formation of starved cells.
Antibiotic resistant strains ofP. putida andEscherichia coli also displayed sensitivity to the combination of nalidixic acid and tetracycline in plate count agar after starvation. 相似文献
7.
Russell B. Lingham Keith C. Silverman Gerald F. Bills Carmen Cascales Manual Sanchez Rosalind G. Jenkins Suzanne E. Gartner Isabel Martin Maria T. Diez Fernando Peláez Sagrario Mochales Yu-Lin Kong Richard W. Burg Maria S. Meinz Leeyuan Huang Mary Nallin-Omstead Scott D. Mosser Michael D. Schaber Charles A. Omer David L. Pompliano Jackson B. Gibbs Sheo B. Singh 《Applied microbiology and biotechnology》1993,40(2-3):370-374
Chaetomellic acids A and B, isolated from Chaetomella acutiseta, are specific inhibitors of farnesyl-protein transferase that do not inhibit geranylgeranyl transferase type 1 or squalene synthase. Chaetomellic acids A and B are reversible inhibitors, resemble farnesyl diphosphate and probably inhibit FPTase by substituting for farnesyl diphosphate. Chaetomellic acid production appears to be widespread within the genus Chaetomella.
Correspondence to: R. B. Lingham 相似文献
8.
Pulkit Singh Wanyi Lu Zunli Lu Adam B. Jost Kimberly Lau Aviv Bachan Bas van de Schootbrugge Jonathan L. Payne 《Geobiology》2023,21(2):175-192
The end-Triassic biodiversity crisis was one of the most severe mass extinctions in the history of animal life. However, the extent to which the loss of taxonomic diversity was coupled with a reduction in organismal abundance remains to be quantified. Further, the temporal relationship between organismal abundance and local marine redox conditions is lacking in carbonate sections. To address these questions, we measured skeletal grain abundance in shallow-marine limestones by point counting 293 thin sections from four stratigraphic sections across the Triassic/Jurassic boundary in the Lombardy Basin and Apennine Platform of western Tethys. Skeletal abundance decreased abruptly across the Triassic/Jurassic boundary in all stratigraphic sections. The abundance of skeletal organisms remained low throughout the lower-middle Hettangian strata and began to rebound during the late Hettangian and early Sinemurian. A two-way ANOVA indicates that sample age (p < .01, η2 = 0.30) explains more of the variation in skeletal abundance than the depositional environment or paleobathymetry (p < .01, η2 = 0.15). Measured I/Ca ratios, a proxy for local shallow-marine redox conditions, show this same pattern with the lowest I/Ca ratios occurring in the early Hettangian. The close correspondence between oceanic water column oxygen levels and skeletal abundance indicates a connection between redox conditions and benthic organismal abundance across the Triassic/Jurassic boundary. These findings indicate that the end-Triassic mass extinction reduced not only the biodiversity but also the carrying capacity for skeletal organisms in early Hettangian ecosystems, adding to evidence that mass extinction of species generally leads to mass rarity among survivors. 相似文献
9.
Rice seedlings accumulate stainable amounts of the 104 and 90 kDa polypeptides in response to high temperature stress. We have purified and raised highly specific polyclonal antisera against both of these polypeptides. In western blotting experiments, we find that these proteins are accumulated to different extents in rice seedlings subjected to salinity (NaCl), water stress, low-temperature stress and exogenous abscisic acid application. These proteins also accumulated when rice seedlings grown in pots under natural conditions were subjected to water stress by withholding watering. Seedlings of Triticum aestivum, Sorghum bicolor, Pisum sativum, Zea mays, Brassica juncea and mycelium of Neurospora crassa showed accumulation of the immunological homologues of both the 104 and the 90 kDa polypeptides, in response to high-temperature stress. We have earlier shown that shoots of rice seedlings exposed to heat shock accumulate a 110 kDa polypeptide which is an immunological homologue of the yeast HSP 104 (Singla and Grover, Plant Mol Biol 22: 1177–1180, 1993). Employing anti-rice HSP 104 antibodies and anti-yeast HSP 104 antibodies together, we provide evidence that rice HSP 104 is different from the earlier characterized rice HSP 110. 相似文献
10.
The structure of costusoside I and costusoside J have been established as 3-O-{β-d-glucopyranosyl (1 → 2)-α-l-rhamnopyranosyl (1 → 2) [α-l-rhamnopyranosyl (1 → 4)]-β-d-glucopyranosyl}-26-O-(β-d-glucopyranosyl)-22α-methoxy 25 R)-furost-5-en-3β, 26-diol and its 22-hydroxy compound respectively, isolated fron the seeds of Costus speciosus. 相似文献