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111.
Human placental alkaline phosphatase was chromatographed on Sepharose derivatives of d- and l-phenylalanine, l-leucine, glycine, aniline and p-aminobenzoic acid in high concentrations of (NH(4))(2)SO(4). Retention on these columns was greatest at the highest concentrations of (NH(4))(2)SO(4). By using decreasing concentrations and changing the types of salts, elution was effected from each of the columns. The (NH(4))(2)SO(4)-mediated retention appeared to be related to the hydrophobic character of the substituted Sepharose, rather than to any specific binding site of the enzyme. It is suggested that this provides a way of controlling hydrophobic affinity chromatography. By use of chromatography on l-phenylalanine-Sepharose and of DEAE-Sephadex chromatography in the presence of Triton X-100 detergent, a preparation of highly purified (1000-fold) human placental alkaline phosphatase was obtained in 22% yield.  相似文献   
112.
The ability to survive of a phytophagous insect, as illustrated by the genus Pieris, is a quantitative phenomenon, not an all or none reaction. This has been shown by various tests involving Pieris rapae and P. protodice on each of six different larval food plants. There are significant genetic differences between these species with regard to survival, growth rate and size differences. Strains of P. rapae have been induced to prefer one or another host-plant by prior conditioning on that plant. Prior conditioning is effective during the life of the larva (1 st to 5th instars), or the individual (larva to adult) or subsequent generations. Hybridization between conditioned strains gives (1) the effect of hybrid vigor and (2) multiple factor differentiation of F1 and F2 progeny. Testing of conditioned strains indicates that the larvae select not only different plants but also different concentrations of mustard oil. The F1 larvae select a concentration intermediate between parental strains. The F2 select a wider range. Similar tests on oviposition selection by adult females derived from conditioned strains indicate that the females follow the larval conditioning pattern, with similar results on inheritance. Conditioned strains have been shown to be alterable; that is, a strain conditioned to one plant can be reconditioned to another and vice versa. The process is constantly reversable as long as there are individuals which survive the changes.
Zusammenfassung Wie an der Gattung Pieris gezeigt wird, ist die Fähigkeit eines phytophagen Insekts, zu überleben, ein quantitatives Phänomen, keine Alles-oder-Nichts-Reaktion. Dies hat sich bei verschiedenen Untersuchungen mit Pieris rapae und P. protodice an jeder von 6 verschiedenen Larven-Futterpflanzen gezeigt. Im Hinblick auf Überlebensdauer, Wachstumsrate und Größenunterschiede bestehen zwischen diesen Arten signifikante genetische Unterschiede. Stämme von P. rapae können durch vorangehende Gewöhnung (conditioning) an eine oder die andere Wirtspflanze zur Bevorzugung der betreffenden Fraßpflanze gebracht werden. Anpassung durch vorangehende Gewöhnung ist während des Larvenlebens (vom 1. bis 5. Stadium) oder während der einzelnen Entwicklung (Larve bis Imago) oder während aufeinanderfolgender Generationen wirksam. Kreuzungen zwischen so angepaßten Stämmen ergaben 1. den Effekt der Hybridsteigerung und 2. die Vielfach-Faktoren-Trennung in der F1-und F2-Nachkommenschaft. Prüfung der angepaßten Stämme zeigten, daß die Larven nicht nur verschiedene Pflanzen, sondern auch verschiedene Konzentrationen von Senföl wählen. Die F1-Larven wählen eine Konzentration, die intermediär zu den von den Ausgangsstämmen bevorzugten liegt. Die F2 wählt einen weiteren Bereich. Entsprechende Untersuchungen über die Wahl der Eiablage-Pflanzen durch reife Weibchen aus angepaßten Stämmen erwiesen, daß die Weibchen den larvalen Gewöhnungsmustern folgen, mit entsprechenden Konsequenzen für die Vererbung. Es ließ sich zeigen, daß angepaßte Stämme abgeändert werden können, d.h. daß ein an eine Wirtspflanzenart gewöhnter Stamm auf eine andere umgestimmt werden kann und umgekehrt. Dieser Vorgang ist konstant umkehrbar, solange nur einzelne Individuen die Veränderungen überleben.


Aided by the National Science Foundation, Washington, D.C., the California Arboretum Foundation, Inc. and the California State College, Los Angeles.  相似文献   
113.
A simple and safe procedure has been described for the preparation of short-chain aliphatic hydroxamic acids in quantities as large as 1 mole and as small as 0.01 mole. The procedure is equally suitable for the preparation of isotopically labeled hydroxamates, as has been demonstrated in the case of 1-14C-acetohydroxamic acid and 3H-acetohydroxamic acid. Some physical and chemical characteristics, including infrared spectra of formo-, aceto-, propiono-, and isobutyro-hydroxamic acids prepared by this method have been described.  相似文献   
114.
Samanea saman has rapid phytochrome-regulated nyctinasty: red light preceding darkness causes pinnules to close while far-rod light allows opening- Not only the initial angle of the pinnules, but the degree of control by phytochrome depends on the “subjective time of day” at which the tissue is exposed. Excised pairs of pinnules close rapidly when submerged in water; such closure is prevented by bubbling oxygen through the water. However, if submergence closure were due solely to low oxygen levels, then nonsubmerged pinnules in a pure nitrogen atmosphere should also close. Instead, they neither close nor respond to light, but they do respond when air is readmitted, indicating that oxygen is necessary for movement rather than for photoreception. The closure of submerged pinnules remains unexplained. Attempts to detect effects of red or far-red on oxygen uptake by pulvinus tissue were unsuccessful. The following method has been used to test the effects of various inhibitors and other substances: pinnules are excised at the first hour of the day, trimmed, submerged in a sealed chamber, given far-red light, and left in darkness while oxygen is bubbled through the medium. Concentrated test solutions are injected either initially or when the red and far-red exposures are given. Thus far, the substances tested have had little or no effect on the phytochrome response.  相似文献   
115.
Capsella embryogenesis: The suspensor and the basal cell   总被引:1,自引:1,他引:0  
Summary The suspensor and basal cell ofCapsella were examined with the electron microscope and analyzed by histochemical procedures. The suspensor cells are more vacuolate and contain more ER and dictyosomes, but fewer ribosomes and stain less intensely for protein and nucleic acids than the cells of the embryo. The end walls of the suspensor cells contain numerous plasmodesmata but there are no plasmodesmata in the walls separating the suspensor from the embryo sac. The lower suspensor cells fuse with the embryo sac wall and the lateral walls of the lower and middle suspensor cells produce finger-like projections into the endosperm. At the heart stage the suspensor cells begin to degenerate and gradually lose their ability to stain for protein and nucleic acids.The basal cell is highly vacuolate and enlarges to a size of 150 X 70. An extensive network of wall projections develops on the micropylar end wall and adjacent lateral wall. The nucleus becomes deeply lobed and suspended in a strand of cytoplasm traversing the large vacuole. The cytoplasmic matrix darkens at the late globular stage and histochemical staining for protein becomes very intense. The basal cell remains active after the suspensor cytoplasm has degenerated. It is proposed that the suspensor and basal cell function as an embryonic root in the absorption and translocation of nutriments from the integuments to the developing embryo.Research supported by NSF grant GB 3460 and NIH grant 5-RO 1-CA-03656-09.  相似文献   
116.
Three experiments were conducted to determine the effect of ultraviolet (UV) radiation on poliovirus-contaminated seawater. In two of the experiments, the effectiveness of the Kelly-Purdy UV Seawater Treatment Unit to inactivate poliovirus type 1 (T(1)) suspended in continuously flowing seawater was determined. In experiment 1, the observed survival ratio of poliovirus T(1) was 2.3 x 10(-4) (99.98% reduction) in 15.7 sec. No virus was detected (<0.2 plaque-forming unit/ml) in 20.6 seconds. The calculated half-life value was 1.29 sec. In experiment 2, the observed survival ratio of poliovirus T(1) was 5.9 x 10(-4) (99.94% reduction) in 11.7 sec. No virus was detected in 15.7 sec. The calculated half-life value was 1.37 sec. In experiment 3, a laboratory-controlled UV experiment designed to closely simulate the geometry of the continuously flowing seawater system, the observed survival ratios of poliovirus T(1) were 9.7 x 10(-3) (99.03% reduction) and 3.6 x 10(-4) (99.96% reduction) in 15 and 30 sec, respectively; the calculated half-life value was 2.38 sec. A statistically significant difference was found between the inactivation rates of poliovirus T(1) in the two test systems. This rate difference was attributed primarily to UV dosage and stirring effects. The data indicated that UV radiation effectively inactivated poliovirus T(1) in flowing seawater. These results validate the efficacy of the Kelly-Purdy UV Seawater Treatment Unit for use in commercial depuration systems.  相似文献   
117.
Effect of Endotoxin on Serum Zinc Concentrations in the Rat   总被引:3,自引:0,他引:3       下载免费PDF全文
Serum zinc concentrations decreased significantly in a dose-dependent response after endotoxin administration in the rat. The reproducibility and sensitivity of the biological response offer a potential bioassay of endotoxin.  相似文献   
118.
William T. Brown 《CMAJ》1970,102(5):510-511
A controlled study designed to evaluate the hypnotic potentiality of methyprylon (300 mg.), glutethimide (500 mg.) and chloral hydrate (1000 mg.) was carried out on 50 in-patients experiencing long-standing insomina. The patients ranged in age from 21 to 60 years, the sexes were equally represented and the clinical diagnoses were psychoneurosis, reactive depression, or anxiety reaction. An interesting feature of the experimental design allowed for the exclusion of placebo reactors before the initiation of the main trials. No difference in effectiveness of maintaining sleep could be established among the three hypnotic agents, indicating that at the usual levels of statistical significance, all three agents were equally effective as hypnotics. However, a significant trend (P = .05) was found for methyprylon (Noludar) to be the most effective and chloral hydrate to be the least effective of the three drugs in maintaining sleep. Methyprylon was found statistically (P = .05) to be the fastest sleep-inducing agent, whereas glutethimide (Doriden) proved to be the slowest of the three hypnotics with respect to sleep induction time.  相似文献   
119.
The in vivo chemical linkage of Haemophilus parainfluenzae deoxyribonucleic acid (DNA) with the H. influenzae genome has been found to occur at a much higher level than is suggested by the low efficiency of the heterospecific transformation of an antibiotic resistance marker. This linkage, about 60% of the level with homospecific DNA, was found to involve alkali-stable bonding. The amount of host DNA label released (about 60%) was about the same as that released during homospecific transformation. Also, over 60% of the H. influenzae cells adsorbing H. parainfluenzae DNA could not form colonies upon plating. This lethality of the heterospecific transformation was not immediate but followed considerable metabolic activity of the host cells. These data are presented to show that the "limited-pairing" hypothesis may be only a partial explanation for the low efficiency of heterospecific transformation. Another hypothesis is presented which takes into account the lethal effect of this kind of transformation.  相似文献   
120.
Summary The fluorescent antibody technique was used to study antigenic relationships betweenParacoccidioides loboi and other pathogenic fungi. The findings suggest thatP. loboi is more closely related antigenically to certainP. brasiliensis strains than to others and that it has antigens in common with the yeast form ofHistoplasma capsulatum, H. duboisii, Blastomyces dermatitidis, Candida albicans and also the mycelial form ofCoccidioides immitis. Serum globulins from 3 cases of keloidal blastomycosis were labelled with fluorescein isothiocyanate. These conjugates showed slight or no reactivity withP. loboi, the yeast forms ofP. brasiliensis, H. capsulatum, H. duboisii andB. dermatitidis, However, they stained brightlyC. albicans, serotypes A and B, the tissue form ofC. immitis and the yeast form ofSporotrichum schenckii. Adsorption of these reagents withC. albicans eliminated all staining except that forS. schenckii. These patients had no history of clinical sporotrichosis.Deceased. Last address: Fundacão Gonçalo Moniz, Salvador, Bahia, Brazil. Requests for reprints should be sent to Dr.William Kaplan.Dr.Miranda is in private practice in Rio de Janeiro, Brazil.  相似文献   
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