首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
The biomass of summer forage and their contributions were surveyed to show that litterfall supported a high-density population of sika deer (Cervus nippon Temminck) in summer on Nakanoshima Island, Toya Lake, Japan. In July 1974, the grassland had the highest productivity among understory vegetations (228±55kgha–1: mean±SE). In deciduous forests, palatable plants occupied only 0.1% of the biomass of 0.872±0.366kgha–1, and deciduous leaves within the reach of deer (=220cm at height) produced 0.208±0.070kgha–1. However, litterfall during this period had the highest productivity, 28.7± 5.3kgha–1. The deer consumed litterfall (75.6% in dry weight), short grasses (17.2%), deciduous forest understory (4.1%), deciduous leaves within the reach of deer (3.0%) and conifer plantation under story (0.1%). It is suggested that the high-density deer population would be maintained by litterfall through the year instead of browsing in deciduous forests, which has been overlooked.  相似文献   

2.
Zusammenfassung Ziel der Abhandlung ist die Untersuchung der grundlegenden Prinzipien einer autonombiologischen Kausalität. Wenn die Biologie in autonomer Weise auf ihr gemässe Prinzipien gegründet werden soll —wie das die Physik in ihrer Sphäre auch durchgeführt hat —, dann muss das biologische Denken sich zunächst von einem Idol befreien, das ihr von der klassischen Physik aufgezwungen ist. Das ist der Begriff des Mechanismus, der bei seiner Schaffung gewiss von grossem Werte auch für die Biologie gewesen ist, der aber heute dem biologischen Denken grossen Schaden dadurch zufügt, dass er es in eine ihm völlig fremde Richtung zwängt.Die Organismen und alle ihre Organe von der einfachsten Zellorganelle bis zum komplexesten Organsystem sind aber keine Mechanismen sondern Holismen (Smuts). Es wird versucht, die wesentlichen Kriterien des Holismusprinzips zu bestimmen. Zunächst gilt für sie das Axiom von v.Ehrenfels, demzufolge jeder Holismus mehr ist als die Summe seiner Teile. Das wird im einzelnen genauer analysiert. Weiterhin gilt für Holismen das Kompensationsprinzip vonGoethe. Damit im Zusammenhang stehen die Prinzipien der spezifischen Energie vonJohannes Müller, das Prinzip vonRedi (Omne Vivum ex Vivo), das Prinzip vonVernadsky über die Konstanz der Biosphäre, das Prinzip der phylogenetischen Kompensationen und das Prinzip von der Ektropie der Biosphäre.Alle diese Prinzipien werden im einzelnen diskutiert und analysiert. In engstem Zusammenhang miteinander bilden sie ein autonomes Axiomengefüge für die Biologische Erkenntnis, durch welches wiederum die eigentümlich biologische Kausalität charakterisiert ist. Genau in diesem Sinne sind Holismen verae causae (Smuts).
Contenido El presente ensayo tiene por fin supremo la investigación de los principios basicos de una autónoma causalidad biologica. Si se quiere fundar la Biologia en sus propios principios autónomos —como se lo ha hecho también con la Fisica misma —, entonces será primeramente necesario que la Biologia se delibera de una ideologia completamente extraña para ella, la cual la Fisica clásica le ha transferido. Esto es el concepto del mecanismo, que en su origin ha sido de gran valor también para la Biologia, pero que hoydia produce enorme daño a la Biologia.Los organismos y todos sus órganos de la mas simple organela celular hasta el mas complicado sistema de órganos sin embargo de ninguna manera no son mecanismos sino al contrario holismos (Smuts). Ahora se ensaya de determinar los criterios esenciales del principio del holismo. Primero es valido para los holismos el axioma de v.Ehrenfels que dice que cada Organismo representa más que la suma de sus partes. Además vale para holismos el principio de la compensación deGoethe. Con esto están relacionados los principios de la energia especifica deJuan Müller, el axioma deRedi (Omne Vivum ex Vivo), el principio deVernadsky acerca de la constancia de la biósfera, el principio de las compensaciones filogenéticas y el principio de la ectropia de la biósfera.Todos los mencionados principios y axiomas serán discutidos y analizados en sus particularidades. En su conjunto representan ellos un sistema de axiomas autónomos para el conocimiento biológico, el cual como tal caracteriza también la asi llamada causalidad biologica. Precisamente en tal sentido son los holismos verae causae (Smuts).


Diese Abhandlung ist Herrn Prof. Dr. v.Buddenbrock in Verehrung zum 70. Geburtstag dargebracht.  相似文献   

3.
The mangrove killifish Rivulus marmoratus was reared at 25°±1°C and 17ppt salinity from 0 to 100 days after hatching (DAH), and its early development was described by examining growth and morphometric parameters, meristic characters (vertebral and fin-ray counts), bone-cartilage development, and pigmentation. Growth was isometric for preanal length, head length, snout length, body depth, pectoral-fin length, dorsal-fin length, anal-fin length, and caudal-peduncle depth. Negative allometric growth was observed in eye diameter and gape size. Meristic counts (mean±SD) for vertebrae (34.2±0.4) and dorsal- (8.6±0.5), anal- (11.4±0.5), and caudal-fin rays (30.2±0.8) were complete at 0 DAH (n=5), whereas pectoral-fin rays and pelvic-fin rays were complete by 30 DAH (14.5±0.4, n=5) and 60 DAH (4.2±0.8, n=5). Full ossification of meristic elements proceeded in the following sequence: vertebrae (by 30 DAH), caudal-, dorsal-, and anal-fin rays (by 60 DAH), pectoral-fin rays (between 60 DAH and 100 DAH), and pelvic-fin rays (by 100 DAH). Both morphological characters and meristic counts indicate that this species can be considered to be a juvenile after 9.8mm in standard length (20 DAH).  相似文献   

4.
Summary The peroxidase-antiperoxidase immunocytochemical technique was used to identify the ACTH/endorphin cells in the porcine pituitary at the ultrastructural level and to determine the precise subcellular localization of the pro-ACTH/endorphin fragments. The cells display different aspects: 1) large, regular shapes with numerous and large secretory granules; 2) small, irregular and angular shapes with small granules aligned along the periphery of the cell; and 3) intermediate forms. The presence of and -endorphin not only in the same cells but also in the same secretory granules that contain ACTH and -LPH clearly indicates that both the precursor or its fragments and the abovementioned peptides are stored in the same granules and released simultaneously by the corticotropic cells. The presence of FSH in some corticotropic cells is also discussed.Abbreviations used in this Article ACTH corticotropin - -MSH -melanotropin (ACTH I–I3) - CLIP corticotropin-like intermediate lobe peptide (ACTH 18–39) - -LPH -lipotropin - -MSH -melanotropin (-LPH 41–58); -endorphin (-LPH 61–91); -endorphin (-LPH 61–76)  相似文献   

5.
Endo--galactosidase (EC 3.2.1.103) ofBacteroides fragilis, at 250 mU ml–1, did not cleave the internal galactosidic linkage of the linear radiolabelled trisaccharide GlcNAc1-6Gal1-4GlcNAc, or those of the tetrasaccharides Gal1-4GlcNAc1-6Gal1-4GlcNAc and Gal1-4GlcNAc1-6Gal1-4Glc. The isomeric glycans which contained the GlcNAc1-3Gal1-4GlcNAc/Glc sequence were readily cleaved.Abbreviations GlcNAc 2-acetamido-2-deoxy-d-glucose - Lact lactose - MT maltotriose - MTet maltotetraose - R MTet chromatographic migration rate in relation to that of maltotetraose  相似文献   

6.
Summary Determinations of current-voltage relationships are widely employed in the characterization of epithelial sodium transport. In order to determine the protocol dependence of transport parameters in the toad urinary bladder, studies were carried out in the presence and absence of amiloride, an inhibitor of active sodium transport. With symmetric positive and negative perturbations of the transepithelial electrical potential difference (0±100 mV) for 30 sec, the amiloride-sensitive current-voltage (i a -) relationship was near linear over the range –75+100 mV, indicating constancy of the conductance a and the apparent electromotive force E Na, lumped parameters of the standard electrical equivalent circuit model of the active transport system. With a reverse protocol (±1000 mV) or 15 min perturbations thei a - relationships were highly nonlinear. Nonlinearity reflected voltage dependence of parameters: perturbations that increased active transport decreased E Na and increased a, as evaluated from 10 sec perturbations of ; slowing of active transport produced the converse changes. These effects are usefully analyzed in both quasi-steady states and true steady states by means of a detailed equivalent circuit incorporating the significant ionic currents across each plasma membrane. Precise understanding of the significance of a and E Na will require characterization of the partial ionic conductances on perturbation of .  相似文献   

7.
Conclusiones Se efectúa el estudio de 5 observaciones del llamado Micetoma maduromicósico de pulmón en sus aspectos, histopatológico, micológico y clínico.Todas ellas pertenecen a mujeres y configuraron el cuadro de cavidad bronquial empastada, anotando el predominio de su localización en el lóbulo superior izquierdo.Se señala la uniformidad de los caracteres morfológicos que presenta la masa miceliana llamada grano en todos los casos estudiados, en los cuales no fué posible individualizar la existencia de órganos de fructificación que permitiéran una clasificación, cuando más no fuera, genérica del hongo observado.Se critica la aplicación del término Micetoma para éstos casos con igual criterio que el clásico, que supone una enfermedad micótica primitiva, razón por la cual se prefiere hablar de cavidad con contenido micótico o maduromicótico.En el único caso que se logró cultivar al hongo parásito, el estudio micológico del mismo permitió aislar una especie del GéneroAspergillua con caracteres morfológicos sumamente atípicos.
Summary The author presents the study of five observations of the so-called Maduromycosis-mycetoma of the lungs in their clinical, histopathologic and mycologic aspects.The pathologic features in all these cases have been found in bronchial cavities of women, situated in the upper lobe of the lung. A compact mycelial mass, the grain, filled up these cavities.In one of the five cases a fungus was cultivated which was classified as belonging to the GenusAspergillus Michelii, with abnormal and atypical features.Short criticism is presented about the concept Maduromycosis mycetoma of the lung, applied by authors designating this process.
  相似文献   

8.
Wen  Zhao  Shuang-Lin  Dong 《Hydrobiologia》2003,492(1-3):181-190
Primary productivity, biomass and chlorophyll-a of size fractionated phytoplankton (<0.22 m, <3 m, <8 m, <10 m, <40 m, <64 m, <112 m and <200 m) were estimated in 6 ponds and 5 experimental enclosures. The results showed that the planktonic algae less than 10 m are important in the biomass and production of phytoplankton in saline–alkaline ponds. The production of size fractionated phytoplankton corresponding to <112 m, <10 m and <3 m in saline–alkaline ponds were 10.5 ± 6.6 , 8.6 ± 5.4 and 0.33 ± 0.1 mgC l–1 d–1, respectively. Mean community respiration rate was 1.80 ± 0.73, 1.69 ± 0.90 and 1.38 ± 1.12 mgC l–1 d–1, respectively. The average production of phytoplankton corresponding to micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) were 1.61, 8.30 and 0.33 mgC l–1 d–1, respectively. The ratio of those to the total phytoplankton production was 15%, 79% and 3%, respectively. The mean respiration rate of the different size groups was 0.11, 0.31 and 1.38 mgC l–1 d–1; the ratio of those to total respiration of phytoplankton was 6%, 17% and 77%, respectively. The production of size-fractionated phytoplankton corresponding to <200 m, <10 m and <3 m in enclosures was 2.19 ± 1.63, 2.08 ± 1.75 and 0.22 ± 0.08 mgC l–1 d-1, respectively. Mean community respiration rates were 1.25 ± 1.55, 1.17 ± 1.42 and 0.47 ± 0.32 mgC l–1 d–1, respectively. The average production of phytoplankton corresponding to micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton was 0.11, 1.86 and 0.22 mgC l–1 d–1, respectively. The ratio of those to the total production of phytoplankton was 5%, 85% and 10%, respectively. The mean respiration rate of different size groups were 0.08, 0.72 and 0.46 mgC l–1 d–1, the ratio of those to total respiration of phytoplankton was 6%, 57% and 37%, respectively. The concentrations of chlorophyll-a of the phytoplankton in the corresponding size of micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) plankton in the experimental ponds were 19.3, 98.2 and 11. 9 g l–1, respectively. The ratio of those to the total chlorophyll-a was 15%, 76% and 9%, respectively. The concentrations of chlorophyll-a of phytoplankton micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton in enclosures were 1.7, 34.3 and 3.0 g l–1, respectively. The ratio of those to the total chlorophyll-a was 4%, 88% and 8%, respectively.  相似文献   

9.
Summary In these experiments, a considerable range of hydroxysteroid dehydrogenases were demonstrated in vertebrate hepatic tissue; 3, 3, 6, 11, 16, 16, 17 and 20 were consistently present.3 hydroxysteroid dehydrogenase was fairly active in mammalian liver, but consistently greater activity was seen with the 3 dehydrogenases which are probably concerned with steroid detoxication and excretion. 6 and 11 hydroxysteroids were only moderately well used, and both these were noticeably better used in male tissue, as were also 3, 3, 16 and 16 hydroxysteroids. All mammalian liver utilised 16, 16 and 17 compounds fairly well, and 20 was consistently but poorly used.This histochemical evidence agrees with biochemical and clinical evidence for the significance and nature of steroid metabolism in the liver. Many of the enzymes showing activity in the liver have known function in the detoxication and elimination of steroids; and 3-hydroxysteroid dehydrogenase is concerned in cholesterol biosynthesis as well as the biosynthesis of progesterane. To have shown contrasting patterns of activity between liver and steroid producing endocrine tissues is further evidence for the specificity of these techniques in the study of dehydrogenase distribution.  相似文献   

10.
The study deals with a comparative analysis of the relative abundances of the carbon isotopes 12C and 13C in the metabolites and biomass of the Burkholderia sp. BS3702 and Pseudomonas putida BS202-p strains capable of utilizing aliphatic (n-hexadecane) and aromatic (naphthalene) hydrocarbons as sources of carbon and energy. The isotope compositions of the carbon dioxide, biomass, and exometabolites produced during the growth of Burkholderia sp. BS3702 on n-hexadecane (13C = –44.6 ± 0.2) were characterized by the values of 13CCO 2 = –50.2 ± 0.4, 13Cbiom = –46.6 ± 0.4, and 13Cexo = –41.5 ± 0.4, respectively. The isotope compositions of the carbon dioxide, biomass, and exometabolites produced during the growth of the same bacterial strain on naphthalene (13C = –21 ± 0.4) were characterized by the isotope effects 13CCO 2 = –24.1 ± 0.4, 13Cbiom = –19.2 ± 0.4, and 13Cexo = –19.1 ± 0.4, respectively. The possibility of using the isotope composition of metabolic carbon dioxide for the rapid monitoring of the microbial degradation of petroleum hydrocarbons in the environment is discussed.  相似文献   

11.
1,3-Fucosyltransferase solubilized from human liver has been purified 40 000-fold to apparent homogeneity by a multistage process involving cation exchange chromatography on CM-Sephadex, hydrophobic interaction chromatography on Phenyl Sepharose, affinity chromatography on GDP-hexanolamine Sepharose and HPLC gel exclusion chromatography. The final step gave a major protein peak that co-chromatographed with 1,3-fucosyltransferase activity and had a specific activity of 5–6 µmol min–1 mg–1 and anM r 44 000 deduced from SDS-PAGE and HPLC analysis. The purified enzyme readily utilized Gal1-4GlcNAc, NeuAc2-3Gal1-4GlcNAc and Fuc1-2Gal1-4GlcNAc, with a preference for sialylated and fucosylated Type 2 acceptors. Fuc1-2Gal1-4Glc and the Type 1 compound Gal1-3GlcNAc were very poor acceptors and no incorporation was observed with NeuAc2-6Gal1-4GlcNAc. A polyclonal antibody raised against the liver preparation reacted with the homologous enzyme and also with the blood group Lewis gene-associated 1,3/1,4-fucosyltransferase purified from the human A431 epidermoid carcinoma cell line. No cross reactivity was found with 1,3-fucosyltransferase(s) isolated from myeloid cells. Examination by Northern blot analysis of mRNA from normal liver and from the HepG2 cell line, together with a comparison of the specificity pattern of the purified enzyme with that reported for the enzyme expressed in mammalian cells transfected with theFuc-TVI cDNA, suggests a provisional identification ofFuc-TVI as the major 1,3-fucosyltransferase gene expressed in human liver.Died June, 1991  相似文献   

12.
Euphorbia characias is a Mediterranean spurge with a diplochorous dispersal system: after a ballistic dispersal that scatters the seeds, some ant species find and retrieve the seeds to their nest (myrmecochorous dispersal). The seed dispersal curve generated by ants in an abandoned field was described and partitioned according to ant size and to the distance to nest entrance from where seeds fell after ballistic dispersal. Both variables (ant size, distance to nest) affected dispersal distance. The seed dispersal curve showed a peak at short distance (median=1m) and a tail extending to 9.4m. The peak and the tail are explained differently. Short distances are usually generated by small ants (Pheidole pallidula and Tapinoma nigerrimum; 0.56±0.41m [n=48]) both from the nearest or farther nest entrances. The tail of the curve is generated disproportionately by big ants (Aphaenogaster senilis and Messor barbarus; 2.09±1.71m [n=61]) from farther nests. Seeds have a much greater probability (P=0.734) of being transported to nests which are not the nearest. This effect is largely due to transportation by big ants.  相似文献   

13.
Summary The basal swellings on the processes of the cone cells of Pteronemobius include conspicuous bodies consisting of a double unit membrane as well as of many granules (-glycogen?). These membranes are infoldings of the cell membrane.According to their site these structures seem to be a continuation of the rhabdome to which they lie very close distally. These bodies probably could—like the rhabdome-act as light guides, and together with pigment prevent an intrusion of light into deeper regions of the head.  相似文献   

14.
UDP-GlcNAc: Man1-6R (1-2)-N-acetylglucosaminyltransferase II (GlcNAc-T II; EC 2.4.1.143) is a key enzyme in the synthesis of complexN-glycans. We have tested a series of synthetic analogues of the substrate Man1-6(GlcNAc1-2Man1-3)Man-O-octyl as substrates and inhibitors for rat liver GlcNAc-T II. The enzyme attachesN-acetylglucosamine in 1-2 linkage to the 2-OH of the Man1-6 residue. The 2-deoxy analogue is a competitive inhibitor (K i=0.13mm). The 2-O-methyl compound does not bind to the enzyme presumably due to steric hindrance. The 3-, 4- and 6-OH groups are not essential for binding or catalysis since the 3-, 4- and 6-deoxy and -O-methyl derivatives are all good substrates. Increasing the size of the substituent at the 3-position to pentyl and substituted pentyl groups causes competitive inhibition (K i=1.0–2.5mm). We have taken advantage of this effect to synthesize two potentially irreversible GlcNAc-T II inhibitors containing a photolabile 3-O-(4,4-azo)pentyl group and a 3-O-(5-iodoacetamido)pentyl group respectively. The data indicate that none of the hydroxyls of the Man1-6 residue are essential for binding although the 2- and 3-OH face the catalytic site of the enzyme. The 4-OH group of the Man-O-octyl residue is not essential for binding or catalysis since the 4-deoxy derivative is a good substrate; the 4-O-methyl derivative does not bind. This contrasts with GlcNAc-T I which cannot bind to the 4-deoxy-Man- substrate analogue. The data are compatible with our previous observations that a bisectingN-acetylglucosamine at the 4-OH position prevents both GlcNAc-T I and GlcNAc-T II catalysis. However, in the case of GlcNAc-T II, the bisectingN-acetylglucosamine prevents binding due to steric hindrance rather than to removal of an essential OH group. The 3-OH of the Man1-3 is an essential group for GlcNAc-T II since the 3-deoxy derivative does not bind to the enzyme. The trisaccharide GlcNAc1-2Man1-3Man-O-octyl is a good inhibitor (K i=0.9mm). The above data together with previous studies indicate that binding of the GlcNAc1-2Man1-3Man- arm of the branched substrate to the enzyme is essential for catalysis. Abbreviations: GlcNAc-T I, UDP-GlcNAc:Man1-3R (1-2)-N-acetylglucosaminyltransferase I (EC 2.4.1.101); GlcNAc-T II, UDP-GlcNAc:Man1-6R (1-2)-N-acetylglucosaminyltransferase II (EC 2.4.1.143); MES, 2-(N-morpholino)ethane sulfonic acid monohydrate.  相似文献   

15.
Summary Candida wickerhamii produces one endocellular and one exocellular -glucosidase. Both enzymes are repressed by glucose in the wild-type strain. In the M7 mutant ofC. wickerhamii, which was previously demonstrated to be derepressed for endocellular -glucosidase biosynthesis, the exocellular -glucosidase is derepressed and hyperproduced when cellodextrins are added to the culture medium. This enzyme, which was produced constitutively in the wildtype, has thus become inducible in the M7 mutant strain. The interest of this strain for industrial production of -glucosidases is discussed.
Resumen Candida wikerhamii produce dos -glucosidasas: una endocelular y otra exocelular. Ambos enzimas son reprimidos por glucosa en la cepa salvaje. Al añadir celodextrina al medio de cultivo del mutante M7 deC. wickerhamii, en el cual se ha demostrado ya la desrepresión de la síntesis de -glucosidasa endocelular, se desreprime la -glucosidasa extracelular obteniéndose una hiperproducción de este enzima. Dicho enzima que era producido de forma constitutiva en el tipo salvaje, se ha convertido en inducible en la cepa mutante M7. Se discute el interés de esta cepa para la producción industrial de -glucosidasas.

Résumé Candida wickerhamii produit deux -glucosidases, l'une endo- et l'autre exocellulaire. Les deux enzymes de la souche sauvage sont réprimées par le glucose. Le mutant M7, chez qui il a été antérieurement constaté que la synthèse de la -glucosidase endocellulaire est déréprimée, l'enzyme exocellulaire est elle aussi déréprimée et hyper-produite lorsque des cellodextrines sont ajoutées au milieu de culture. Cette enzyme, qui est constitutive chez la souche sauvage, est donc devenue inductible chez le mutant M7. Cette souche est intéressante pour la production industrielle de -glucosidases.
  相似文献   

16.
A novel syrup containing neofructo-oligosaccharides was produced from sucrose (Brix 70) by whole cells of Penicillium citrinum. The efficiency of fructo-oligosaccharides production was more than 55% and those of the main carbohydrate components, 1-kestose (Fruf 21Fruf 21 Glc), nystose (Fruf 21Fruf 21 Fruf 21 Glc) and neokestose (Fruf 26 Glc12 Fruf), were 22, 14 and 11%, respectively.  相似文献   

17.
(2S,1'S,2'R)-2-(Carboxycyclopropyl)glycine (L-CCG III) was a substrate of Na+-dependent glutamate transporters (GluT) in Xenopus laevis oocytes (IC50 13 and 2 M for, respectively, EAAT 1 and EAAT 2) and caused an apparent inhibition of [3H]L-glutamate uptake in mini-slices of guinea pig cerebral cortex (IC50 12 M). In slices (350 M) of guinea pig cerebral cortex, 5 M L-CCG III increased both the flux of label through pyruvate carboxylase and the fractional enrichment of glutamate, GABA, glutamine and lactate, but had no effect on total metabolite pool sizes. At 50 M L-CCG III decreased incorporation of 13C from [3-13C]-pyruvate into glutamate C4, glutamine C4, lactate C3 and alanine C3. The total metabolite pool sizes were also decreased with no change in the fractional enrichment. Furthermore, L-CCG III was accumulated in the tissue, probably via GluT. At lower concentration, L-CCG III would compete with L-glutamate for GluT and the changes probably reflect a compensation for the missing L-glutamate. At 50 M, intracellular L-CCG III could reach > 10 mM and metabolism might be affected directly.  相似文献   

18.
Epinephrine at 10–100 M stimulated somatic embryogenesis from orchardgrass (Dactylis glomerata L.) leaves cultured on SH medium with 30 M of indole-3-acetic acid (IAA). Ethylene emanation was increased at epinephrine concentrations greater than 10 M. Decarboxylation by the leaves of [1-14C]IAA included in the medium was decreased almost 3-fold by 10 M epinephrine. Epinephrine at 10 M enhanced the number of regenerated plants on SH medium with 30 M dicamba (SH-30). Ethylene emanation was increased by epinephrine concentrations of 500 M and greater included in SH-30 but somatic embryogenesis was decreased. Addition of 8 M CoCl2, 6H2O (an ethylene biosynthesis inhibitor) to medium with 500 M epinephrine decreased ethylene emanation to the control level but did not alleviate the decreased embryogenic response.  相似文献   

19.
Summary The time course of binding of the fluorescent stilbene anion exchange inhibitor, DBDS (4,4-dibenzamido-2,2-stilbene disulfonate), to band 3 can be measured by the stopped-flow method. We have previously used the reaction time constant, DBDS, to obtain the kinetic constants for binding and, thus, to report on the conformational state of the band 3 binding site. To validate the method, we have now shown that the ID50 (0.3±0.1 m) for H2-DIDS (4,4-diisothiocyano-2,2-dihydrostilbene disulfonate) inhibition of DBDS is virtually the same as the ID50 (0.47±0.04 m) for H2-DIDS inhibition of red cell Cl flux, thus relating DBDS directly to band 3 anion exchange. The specific glucose transport inhibitor, cytochalasin B, causes significant changes in DBDS, which can be reversed with intracellular, but not extracellular,d-glucose. ID50 for cytochalasin B modulation of DBDS is 0.1±0.2 m in good agreement withK D =0.06±0.005 m for cytochalasin B binding to the glucose transport protein. These experiments suggest that the glucose transport protein is either adjacent to band 3, or linked to it through a mechanism, which can transmit conformational information. Ouabain (0.1 m), the specific inhibitor of red cell Na+,K+-ATPase, increases red cell Cl exchange flux in red cells by a factor of about two. This interaction indicates that the Na+,K+-ATPase, like the glucose transport protein, is either in contact with, or closely linked to, band 3. These results would be consistent with a transport proteincomplex, centered on band 3, and responsible for the entire transport process, not only the provision of metabolic energy, but also the actual carriage of the cations and anions themselves.  相似文献   

20.
The main carotenoid of Flavobacterium strain R1560 has been identified as (3R,3R)-zeaxanthin. Also present were small amounts of 15-cis-phytoene, phytofluene, -carotene (7,8,7,8-tetrahydro-, -carotene plus 7,8,11,12-tetrahydro-, -carotene), neurosporene, lycopene, -zeacarotene, -carotene, -carotene, -cryptoxanthin, rubixanthin, 3-hydroxy--zeacarotene and several apo-carotenals. Zeaxanthin production was inhibited by nicotine (10 mM), and lycopene and rubixanthin accumulated. The biosynthesis of zeaxanthin is discussed in terms of pathways and also of half-molecule reaction sequences. The presence of zeaxanthin may be a characteristic of a group of Flavobacterium species, and may thus be useful in the taxonomic classification of these organisms.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号