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1.
Summary Effects of - or -D-glucose on the respiration of germinated spores (only germinated spores not including swollen spores and elongated spores) ofBacillus subtilis andB. megaterium were studied. In our conditions, net amount of oxygen consumed by 1010 germinated spores ofB. subtilis per min after addition of - or -D-glucose was 1.6 g or 6.6 g (/=4.13), while that byB. megaterium was 4.5 g or 6.8 g (/=1.51), respectively. However, the net amounts of oxygen consumed by 1010 vegetative cells per min after addition of - or -D-glucose were identical, forB. subtilis in both cases 443.0 g and forB. megaterium in both cases 604.4 g.  相似文献   

2.
Intraluminal injections (15 l) of either concanavalin A (125 g) or ionophore A 23187 (0.01 mol) induced a decidual cell reaction (DCR) in the uterus of day 4.5 pseudopregnant mice. However, when these agents were administered in different combinations with each other or with CaCl2 (15 mol) and phorbol-12-myristate-13-acetate (1.6 nmol), interacting effects occurred to either enhance or inhibit each of the others' independent deciduogenic capacities. The results suggest that the polyphosphatidylinositol pathway and Ca2+ are involved in the induction of the DCR in mice with complex interactions occurring between the active components of the pathway to modulate the outcome of the transformation process.  相似文献   

3.
Summary Analogues of glutamic acid, -methylglutamic acid and glutamine in which the -or -COOH groups are replaced by PO3H2 or P(O)(OH3)OH functions competitively inhibit rat liver glutamine synthetase. The K1 values are comparable to or lower than KM for L-glutamate.This study was supported by grant R.1.9.  相似文献   

4.
Summary Uptake ofd-glucose anomers by isolated rat retina was studied. After 3 min incubation at 37°C in the presence of or anomer (750 g/ml), a significantly greater uptake (1.32 mg/g wet tissue) of -anomer was observed compared with that of -d-glucose (1.11 mg/g wet tissue). This result and other data suggest that the carrier ford-glucose transport in the retina prefers the -anomer stereospecifically.Acknowledgment. The authors are grateful to Mr S. Suzuki for his technical assistance.  相似文献   

5.
Summary Pubertal development in female deer mice,Peromyscus maniculatus, was stimulated by exposure to light cycles of LD 168, LD 630 or LD 654, but not by exposure to cycles of LD 618 or LD 642. These results support the hypothesis that female deer mice use a circadian rhythm of responsiveness to light to measure photoperiodic time.This investigation was supported in part by National Science Foundation Grant PCM 8116880 and U.S. Environmental Protection Agency Grant CR809428010. H.U. is the recipient of Research Ca-reer Development Award 5 KO4 HD00276-02 from the National Institute of Child Health and Human Development.  相似文献   

6.
Summary In the rabbit jejunum, the elevation of temperature within the range of 25–37°C diminished the sensitivity to noradrenaline (NA) for both the relaxation and amplitude inhibition. The relaxation by NA was mainly mediated via adrenergic -receptors at 25, 30 or 37°C. The amplitude inhibition was mediated via -receptors at 37°C, and both - and -receptors at 30 or 25°C.  相似文献   

7.
The paper reports on the molecular analysis of samples of approximately 5,300-year-old grass found at the alpine archaeological site where the so-called Tyrolean Iceman was discovered. The grass comes from a cloak made of long grass blades and/or the stuffing of the snow footwear worn by the Iceman. The results show that while the largest fraction of the DNA extractable from the grass is of foreign origin, a much smaller part belongs to the original genetic material of the grass itself, and can be used as a valuable taxonomic clue to the plant species utilized by neolithic men to manufacture their equipment. On the other hand, the foreign DNA, or at least a portion of it, comes from microorganisms-mainly filamentous fungi and unicellular algae-which seem to have been associated with the grass since the time the grass was harvested.  相似文献   

8.
Hotspots of homologous recombination   总被引:9,自引:0,他引:9  
Homologous recombination occurs at higher than average frequency at and near hotspots. Hotspots are special nucleotide sequences recognized by proteins that promote, directly or indirectly, a rate limiting step of recombination. This review focuses on two well-studied examples, the Chi sites of the bacteriumEscherichia coli and the M26 site of the fission yeastSchizosaccharomyces pombe. Chi, 5 G-C-T-G-G-T-G-G 3, is recognized by the RecBCD enzyme, which nicks the DNA near Chi and produces a 3-ended single-stranded DNA tail; this tail is a potent substrate for homologous pairing by RecA and single-stranded DNA binding proteins. M26, 5 A-T-G-A-C-G-T 3, is recognized by a heterodimeric protein and stimulates, by an as-yet-unknown mechanism, meiotic recombination at and near theade6 gene. Additional hotspots in bacteria, fungi, and mammals enhance recombination directly or indirectly via a variety of mechanisms. Although hotspots are widespread among organisms, the biological role of their localized enhancement of recombination remains a matter of speculation.  相似文献   

9.
Summary In the oocytes ofAplysia depilans it has been observed electronmicroscopically that gemmae or daughter-nucleoli separate from the nucleolus. These gemmae after having overcome the nuclear membrane, would aggregate together, even after transformation, into yolk globules. These observations seem to give plausibility to the hypothesis that there is a close relationship between production of ribonucleoproteic material by the nucleolus and yolk production.  相似文献   

10.
Summary The new methods for the production of 19-norsteroids described involve the conversion of 5-halogen-6-hydroxy-steroids into the corresponding 5-halogen-6:19-ethers either with lead tetraacetate or by the hypoiodite reaction8,10. The 6:19-oxygen bridge is then opened reductively either directly or after oxidation of the 6:19-ethers to lactones or preferably after introduction of a 4,6-3-oxo grouping. Acylolytic cleavage of the 4-3-oxo-6:19-ethers followed by alkaline hydrolysis gives 4,6-3-oxo-19-hydroxy-steroids. The 19-hydroxycompounds formed are easily converted into 19-norsteroids by known methods.

Über Steroide, 189. (vorläufige) Mitteilung; 188. Mitt. vgl.J. Kalvoda, J. Schmidlin, G. Anner undA. Wettstein, Exper.18, 398 (1962).  相似文献   

11.
Summary The influence of somatostatin on tumor cell growth was studied in vivo in mice (sarcoma 180 ascites tumor and Lewis lung tumor) and in vitro on nontransformed and polyoma-transformed cell lines. 4 or 20 g/100 g of cyclic somatostatin and 4 g/100 g of linear protamin Zn-bound somatostatin were injected s.c. twice daily in the in vivo study. Cyclic somatostatin (1, 4 or 10 g/ml) was added twice daily to the cell cultures. Somatostatin administration influenced neither the survival of animals nor the growth rate of cultured cell lines. *** DIRECT SUPPORT *** A2025117 00011  相似文献   

12.
Summary The colchicin-induced nuclear inclusions are a postmitotic phenomena. Fusing chromosome vesicles often include a portion of cytoplasm, surrounded by persisting parts of the vesicle membranes (indirect or membraned n.i.). This membrane sometimes degenerates; the n.i. then lies free in the karyoplasm (secondarily direct or free n.i.).  相似文献   

13.
Summary Axillary 5-androst-16-en-3-one (5-androstenone) levels were found to be significantly higher in men than in women but do not vary between left and right axillae, are not related to age, handedness or degree of hirsutism (in women) nor to anosmia to this steroid. In men (but not in women), levels are related linearly to axillary cholesterol concentrations but not to squalene. Olfactory thresholds for 5-androstenone varied widely, the lowest recorded being 0.2 ppb, but there was no difference in thresholds between men and women. Women (70%) found the smell repellant but anosmia did not differ greatly between men and women (9–20%). Anosmia to the smell of 5-androst-16-en-3-ol was most marked in women (90%) rather than in men (45%). Axillary 5-androstenone values were generally consistent with the musky or strong smells of male axillary extracts, compared with the sweet smell of those from female subjects.Supported by the Herbert Dunhill Trust.  相似文献   

14.
Summary The free radical oxidation of 1 and 6-tetrahydrocannabinol has been examined by spin trapping techniques and intermediates that would lead to cannabinol have been trapped. The 1st step in the oxidation of 1-THC involves the removal of 3-H, while for 6-THC, either 2-H or 5-H. Intermediates were isolated which could be pyrolysed to the diene and cannabinol.  相似文献   

15.
The mechanism by which the fertilization envelope (FE) is able to protect the embryo of fish until hatching is almost unknown, except for its function as a physical barrier. FE extract from activated or fertilized eggs of the fishSalmo gairdneri was demonstrated to contain enzyme activities using an agar plate enzyme assay. The enzymes apparently active were carboxymethylcellulase (cellulase; EC 3.2.1.4), laminaranase (endo-1,3(4)--glucanase; EC 3.2.1.6), carboxymethylchitinase (chitinase; EC 3.2.1.14), xylanase (endo-1,4--xylanase; EC 3.2.1.8), mannanase (mannan 1,2-(1,3)--mannosidase; EC 3.2.1.77), dextranase (EC 3.2.1.11), a protease and lysozyme (EC 3.2.1.17). The FE extract exerted an antifungal or fungicidal action on the fungusSaprolegnia parasitica, whereas an extract from the vitelline envelopes (VE) has no apparent enzyme activity nor antifungal or fungicidal action. Enzymes acquired by the FE through the cortical reaction may have an important defensive role, protecting the embryo against invaders or pathogens.  相似文献   

16.
There is considerable evidence suggesting that the switch from to and chain production after birth is due, in part, to silencing of the genes by stage-specific factors which bind to their promoters and to the competition from the adult ( and ) genes for a common enhancer element located in the locus control region. As a consequence one can expect that the increased Hb F production in adults with hereditary persistence of fetal hemoglobin or -thalassemia is directed mainly by -globin genes in cis to the deletion(s) responsible for these conditions. Here we review data on heterozygotes with -, -, or -thalassemia, who also had anAT mutation, in cis or in trans, which was used as a marker of gene expression. The results show that a deletion affecting adult genes favors the expression of genes in cis, while the deletion of a single gene does not affect the expression of the gene in cis but leads to a faster switch postnatally.  相似文献   

17.
Summary Daily administration for 3 days of cortisone (25 g/g b.wt), thyroxine (1 g/g b.wt) or insulin (12.5 mU/g b.wt) to 8-day-old suckling mice does not induce a premature decrease of the phosphohydrolase activity of intestinal glucose-6-phosphatase.Supported by grant MA-5969 from the Medical Research Council of Canada (D.M.). C.M. is a recipient of a studentship from MRC of Canada. D.M. is a chercheur-boursier du Conseil de la recherche en santé du Québec.  相似文献   

18.
Summary Lack of dietary ascorbic acid lowered plasma levels of ascorbic acid but failed to change levels of brain norepinephrine or dopamine.Investigators adhered during the research described in this report to the policy set forth in the Guide for the Care and Use of Laboratory Animals by the Committee on Revision of the Guide for Laboratory Animal Resources, National Research Council.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.  相似文献   

19.
Chemical ecology of oviposition in phytophagous insects   总被引:3,自引:0,他引:3  
Summary Selection of a suitable site for oviposition by phytophagous insects is critical for successful development of the offspring. The behavioral events leading to oviposition are mediated to a large extent by chemical cues associated with potential host plants. Orientation and landing are primarily guided by volatile constituents of a plant, whereas assessment of a leaf surface depends on contact stimuli. Chemical mechanisms that ensure adequate spacing of progeny on limited resources include the production of oviposition-deterring pheromones as well as recognition of plant constituents released as a result of previous damage. Perception of chemical cues that affects oviposition involves receptors on antennae, tarsi, mouthparts or the ovipositor. Complex behavior such as tarsal drumming or stem runs may serve to provide increased receptor contact with chemical stimuli. Abiotic and biotic environmental factors often influence the production or release of behavior-modifying chemicals by a plant, and therefore affect oviposition preferences. Plant chemistry may be involved in associative learning, but may also lead to mistakes. Thus a clear correlation between oviposition preference and offspring success does not always exist.  相似文献   

20.
Summary -MSH, -MSH and ACTH bave been localized in the cells of hypophyseal intermediate lobe by fluoresence histoimmunological technics. Elaboration and excretion of these polypeptides are enhanced after dehydration or adrenalectomy. The most evident variations are seen with -MSH and ACTH after dehydration, with -MSH after adrenalectomy.  相似文献   

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