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31.
R. S. Singh S. K. Jain 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1971,41(2):79-84
Summary Surveys for polymorphisms in natural populations of A. barbata sampled in California grasslands had provided evidence for widespread monomorphism and rather localized polymorphic areas in the north coastal and San Francisco regions, based on a set of morphological and isoenzymatic marker loci. Since this species, like many other annuals, was introduced from the Mediterranean region during the Spanish mission period, a comparative study of the Canadian-Welsh collections of Avena species from the Mediterranean region was undertaken using various plant characters and starch gel electrophoresis to analyze variants for esterase, phosphatase and peroxidase systems. A total of 96 samples including 73 of A. barbata and 23 of A. hirtula were studied and the results were scored to compute the polymorphism indices. In both species, only 10 to 15 percent sites showed any significant degree of polymorphism of which a majority seemed to originate from localized regions in Italy and Turkey; a part of this observed lack of within-sample variation might be the result of small sample size. In general, the patterns of variation in A. barbata from the California surveys and the present analyses seemed to be very similar and raised some interesting questions on (a) the colonizing history of introduced materials (b) the factors underlying such marked patterns of geographical variation, and (c) the current evolutionary changes occurring in these two broad, disjunct areas of species distribution.
This work was supported in part by a grant from the National Science Foundation (GB 8627). 相似文献
Zusammenfassung Untersuchungen der Polymorphismen in natürlichen Populationen von A. barbata im kalifornischen Weideland hatten einerseits zum Nachweis eines weit verbreiteten Monomorphismus und andererseits streng lokalisierter polymorpher Bereiche in der nördlichen Küsten- und San Francisco-Region geführt, wobei eine Anzahl morphologischer und isoenzymatischer Markerloci zugrunde gelegt wurde. Da diese Art, wie viele andere Annuelle auch, während der spanischen Missionsperiode aus der Mittelmeerregion eingeführt wurde, wurde eine vergleichende Untersuchung der Canadian-Welsh-Sammlungen von Avena-Arten aus der Mittelmeerregion anhand verschiedener Merkmale der Pflanzen und der Stärkegelelektrophorese-Untersuchung auf Esterase-, Phosphatase- und Peroxydase-Systeme durchgeführt. Es wurde eine Gesamtheit von 96 Stichproben, bestehend aus 73 A. barbata und 23 A. hirtula, untersucht und die Ergebnisse zur Berechnung von Polymorphismus-Indices verwendet. In beiden Arten zeigten nur 10 bis 15% der Herkünfte einen signifikanten Polymorphismusgrad. Von ihnen scheint die Mehrzahl von lokalisierten Regionen in Italien und Griechenland abzustammen. Ein Teil des beobachteten Fehlens einer Variation innerhalb der Stichproben könnte eine Folge des geringen Stichprobenumfangs sein. Im allgemeinen scheinen die Variationsmuster der kalifornischen Untersuchungen und die der vorliegenden Analysen von A. barbata sehr ähnlich zu sein. Das führt zu einigen interessanten Fragen nach a) der Besiedelungsgeschichte des eingeführten Materials, b) den Faktoren, die derart auffallenden Mustern der geographischen Variation unterliegen und c) den laufenden evolutionären Änderungen, die in diesen beiden großen, voneinander getrennten Gebieten der Artverteilung auftreten.
This work was supported in part by a grant from the National Science Foundation (GB 8627). 相似文献
32.
Lung growth induced by hypoxia 总被引:3,自引:0,他引:3
33.
34.
B. C. Raychaudhuri S. P. Jain K. G. Yadva 《International journal of biometeorology》1964,8(2):137-145
Evidence is given that the thermal time-constant (ratio of heat stored to heat transmitted) is an effective and simple criterion for the assessment of thermal performance of building fabrics subjected to unsteady heat flow and brings out an optimum value of 20 hr for efficient and economic design. Further, it discusses the mutual interactions between the internal surface temperatures of an enclosure suggesting the inadequacy of the time-lag property concept of any building element taken individually.
Zusammenfassung Es wird nachgewiesen, dass die thermische Zeitkonstante (d.i. das VerhÄltnis von WÄrmespeicherung zu WÄrmedurchfluss) ein ausreichendes und einfaches Kriterium für die AbschÄtzung der thermischen Vollkommenheit von GebÄuden ist, die einem unstetigen WÄrmeeinfluss ausgesetzt sind und einen optimalen Wert von 20 Stunden als ausreichend und ökonomisch aufweisen. Ferner interpretiert diese Grösse die wechselseitige Beziehung zwischen den OberflÄchentemperaturen im geschlossenen Raum und weist darauf hin, dass die Summe der Zeitkonstanten eines jeden einzelnen Bauelementes für sich nicht als Gesamtmass brauchbar ist.
Resume I1 est prouvé ici que la constante thermique de temps (rapport entre la chaleur emmagasinée et la chaleur transmise) est un critère simple et suffisant pour définir les propriétés thermiques des éléments constitutifs d'immeubles. Ce rapport correspond à un flux de chaleur non-uniforme et atteint son optimum au voisinage de 20 heures comme valeur d'efficacité en tenant compte de facteurs économiques. On discute en outre l'action réciproque de la température des surfaces intérieures d'une pièce. On démontre enfin que la somme des constantes de temps de chaque élément de l'immeuble pris individuellement n'est pas propre à définir l'ensemble.相似文献
35.
Saroj Sanan Geeta Sharma Rakesh Malhotra Devindar P. Sanan Parveen Jain Prem Vadhera 《Free radical research》1989,6(1):29-38
Haemorrhagic shock was produced in anaesthetized dogs, by rapid arterial bleeding to mean arterial blood pressure 35 mmHg, and maintained oligaemic for 4 h followed by return of withdrawn blood(R0WB). Dogs were observed for 72 h after ROWB for survival and recovery, and, for histopathological (HP) studies on liver, dogs were sacrificed 2 h after ROWB in non-survival experiments. Desferrioxamine mesylate (25mg/kg) was administered intra-muscularly at 2,3 and 4h after blood loss in survival experiments and for HP studies the drug was given at 4 h in one group and at 2 h plus 4 h after blood loss in the second group. With the drug given at 3 or 4h, survival was 70% and 100% while in the 2h and the untreated groups it was 50%. Recovery was rapid in all the drug treated survivors, few became conscious within 30min. showed slight activity by 4-6 h, all were almost normally active by 24 and fully so by 72 h after ROWB. All the 5 control survivors remained unconscious/drowsy upto 24 h; 3 were sluggish at 72 h. By group analysis, serum iron elevation during the oligaemic and at the end of the post-oligaemic phase was less in the drug-treated animals. HP changes of shock in the liver studied by light microscopy, were markedly reduced in severity and were less prevalent in the drug-treated dogs. The salutory effects of desferrioxamine may be due to inhibition of iron catalyzed free-radical production and tissue damage, through its strong iron chelating action. It may have a therapeutic advantage in this emergency condition without the disadvantages of toxicity inherent in prolonged use. 相似文献
36.
D. K. Jain L. M. Bordeleau 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,80(6):795-800
Summary Mutagenesis provoked by exposure at elevated temperature of the cold-adapted, arctic Rhizobium strain N31 resulted in the generation of five deletion mutants, which exhibited loss of their smaller plasmid (200 kb), whereas the larger plasmid (> 500 kb) was still present in all mutants. Deletion mutants did not show differences from the wild type in the antibiotic resistance pattern, the carbohydrates and organic acids utilization, and the growth rate at low temperature. However, deletion mutants differed from the wild type and among themselves in the ex planta nitrogenase activity, the nodulation index, and the symbiotic effectiveness. The deletion mutant N31.6rif
r showed higher nodulation index and exhibited higher nitrogenase activity and symbiotic efficiency than the other deletion mutants and the wild type. The process of deletion mutation resulted in the improvement of an arctic Rhizobium strain having an earlier and higher symbiotic nitrogen fixation efficiency than the wild type. 相似文献
37.
J J Grabowski C R Bertozzi J R Jacobsen A Jain E M Marzluff A Y Suh 《Analytical biochemistry》1992,207(2):214-226
Photoacoustic calorimetry is shown to be a simple, precise, and accurate method for the quantification of the photophysics of a fluorescence probe, e.g., dansylamide, in a variety of solvents. This technique, which is described in detail, provides a direct measurement of the energy that is released nonradiatively following photostimulation, and can therefore be used to indirectly determine the amount of energy released via luminescent pathways. Photoacoustic calorimetry combined with established absorption and fluorescence methodologies provides a complete arsenal for characterizing the photophysical properties of many systems. Comparison of the photoacoustic signal for dansylamide versus standard compounds (ferrocene, tetraphenylethylene, 8-anilinonaphthalene-1-sulfonate, and/or 5,5'-dithiobis(2-nitrobenzoic acid) in 12 different solvents gave fh values (fraction of each absorbed 337.1-nm photon returned as heat) from a low of 0.530 in 1,4-dioxane to a high of 0.973 in water. The trend noted with solvent polarity is different and more revealing than that determined by the more classical approach of examining either the wavelength of the emission maximum or the fluorescence quantum yield. 相似文献
38.
Optimization of biolistic method for transient gene expression and production of agronomically useful transgenic Basmati rice plants 总被引:4,自引:0,他引:4
We have developed a reproducible biolistic procedure for the efficient transformation of embryogenic suspension cells of an improved aromatic Indica rice variety, Pusa Basmati 1. The -glucuronidase gene was used to assay transient transformation; other plasmids carrying either a potato protease inhibitor 2 (Pin2) gene, or a late embryogenesis-abundant protein (LEA3) gene from barley, were used for the optimization of biolistic process and transgenic plant production. After optimization of the procedure, over 600 transient transformants and at least five fertile plants showing integrative transformation were obtained per bombarded filter. At least 30% of the plants were derived from independent transformation events. The new improved procedure involves the use of a reporter gene or other useful genes driven by the strong rice actin 1 gene (Act1) promoter, osmotic pre-conditioning of cells for 24 h on medium supplemented with 0.25 M mannitol prior to bombardment, use of gold particles for DNA delivery, and use of plant regeneration medium with high (1.0%) agarose concentration. 相似文献
39.
Forest density expressing the stocking status constitutes the major stand physiognomic parameter of Indian forest. Density
and age are often taken as surrogate to structural and compositional changes that occur with the forest succession. Satellite
remote sensing spectral response is reported to provide information on structure and composition of forest stands. The various
vegetation indices are also correlated with forest canopy closure. The paper presents a three way crown density model utilizing
the vegetation indices viz., advanced vegetation index, bare soil index and canopy shadow index for classification of forest
crown density. The crop and water classes which could not be delineated by the model were finally masked from normalized difference
vegetation index and TM band 7 respectively. The rule based approach has been implemented for land use and forest density
classification. The broad land cover classification accuracy has been found to be 91.5%. In the higher forest density classes
the classification accuracy ranged between 93 and 95%, whereas in the lower density classes it was found to be between 82
and 85%. 相似文献
40.
Perturbation of syntrophic isobutyrate and butyrate degradation with formate and hydrogen 总被引:1,自引:0,他引:1
The effect of formate and hydrogen on isomerization and syntrophic degradation of butyrate and isobutyrate was investigated using a defined methanogenic culture, consisting of syntrophic isobutyrate-butyrate degrader strain IB, Methanobacterium formicicum strain T1N, and Methanosarcina mazeii strain T18. Formate and hydrogen were used to perturb syntrophic butyrate and isobutyrate degradation by the culture. The reversible isomerization between isobutyrate and butyrate was inhibited by the addition of either formate or hydrogen, indicating that the isomerization was coupled with syntrophic butyrate degradation for the culture studied. Energetic analysis indicates that the direction of isomerization between isobutyrate and butyrate is controlled by the ratio between the two acids, and the most thermodynamically favorable condition for the degradation of butyrate or isobutyrate in conjunction with the isomerization is at almost equal concentrations of isobutyrate and butyrate. The degradation of isobutyrate and butyrate was completely inhibited in the presence of a high hydrogen partial pressure (>2000 Pa) or a measurable level of formate (10 muM or higher). Significant formate (more than 1 mM) was detected during the perturbation with hydrogen (17 to 40 kPa). Resumption of butyrate and isobutyrate degradation was related to the removal of formate. Energetic analysis supported that formate was another electron carrier, besides hydrogen, during syntrophic isobutyrate-butyrate degradation by this culture. (c) 1996 John Wiley & Sons, Inc. 相似文献