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71.
Christian W. B. Bachem Zsofia Banfalvi Eva Kondorosi Jeff Schell Adam Kondorosi 《Molecular & general genetics : MGG》1986,203(1):42-48
Summary
R. meliloti primarily nodulates Medicago sativa but cannot nodulate Macroptilium atropurpureum. By introducing an 11.4 kb region into R. meliloti from the Symplasmid of Rhizobium strain MPIK3030, the host range of the R. meliloti transconjugants were shown to be extended to M. atropurpureum, one of the hosts of MPIK3030 but not normally nodulated by R. meliloti. The region responsible for host range extension was isolated by mass conjugating a clone bank from MPIK3030 into the R. meliloti wild type, and subsequent screening for nodulation on M. atropurpureum. Using deleted derivatives of a plasmid reisolated from endosymbiotic bacteria, the host range region was further narrowed down to three EcoRI fragments. Tn5 mutagenesis allowed the isolation of three discrete regions on an 11.4 kb section, which are involved in the extension of host range to M. atropurpureum. Finally, complementation experiments performed with R. meliloti common nod and hsn mutants indicated that none of the genes involved in the early steps of nodulation, including host-range functions, can be complemented by genes carried on the 11.4 kb fragment derived from MPIK3030. 相似文献
72.
Daniel Chappard Christian Alexandre Sabine Palle George Riffat 《Biotechnic & histochemistry》1986,61(2):93-96
Polyester fibers are not dissolved by either glycol methacrylate or methyl methacrylate. Commercial polyester wadding is consequently an advantageous material to use in getting precise orientation of tissue specimens during embedding in methacrylate. 相似文献
73.
Daniel Chappard Christian Alexandre Sabine Palle Georges Riffat 《Biotechnic & histochemistry》1986,61(3):145-149
A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method. 相似文献
74.
Metabolism and Solubilization of Cellulose by Clostridium cellulolyticum H10 总被引:9,自引:2,他引:7
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When Clostridium cellulolyticum was grown with cellulose MN300 as the substrate, the rates of growth and metabolite production were found to be lower than those observed with soluble sugars as the substrate. At low cellulose concentrations, the growth yields were equal to those obtained with cellobiose. The main fermentation products from cellulose and soluble sugars were the same. Up to 15 mM of consumed hexose, a change in the metabolic pathway favoring lactate production similar to that observed with soluble sugars was found to occur concomitantly with a decrease in molar growth yield. With cellulose concentrations above 5 g/liter, accumulation of soluble sugars occurred once growth had ceased. Glucose accounted for 30% of these sugars. A kinetic analysis of cellulose solubilization revealed that cellulolysis by C. cellulolyticum involved three stages whatever cellulose concentration was used. Analysis of these kinetics showed three consecutive enzymatic activity levels having the same Km (0.8 g of cellulose per liter, i.e., 5 mM hexose equivalent) but decreasing values of Vmax. The hypothesis is suggested that each step corresponds to differences in cellulose structure. 相似文献
75.
Summary Home ranges of the Galapagos land iguana (Conolophus pallidus) were examined with respect to food availability and the thermal environment. Activity patterns, the amount of space used per day, and time required to use the entire home range were also investigated. The effects of, and the relationships between, these factors vary seasonally, as do home range sizes and preferred body temperatures.Food supplementation experiments resulted in only temporary reductions in use of space. Home range sizes were not different between the seasons with the least (Fall) and the most (Hot) food availalble, but home ranges were significantly smaller in Garua when food supplies were low, but not as low as in Fall. Calculations of metabolic expenditures in each season suggests that food availability alone does not explain seasonal patterns of home range size in this species.The thermal environment within each home range was characterized by microclimatic measurements and measurements of the area of sun, shade, and semi-shade. An index with units of m2h was used to quantify the thermal quality of each home range. Iguanas exploited optimal (with respect to body temperature) conditions more than would be expected from random use of their home ranges. Thermal transients (due to large body size) and optimal conditions were exploited to the largest degree in Fall.During Garua, low metabolic rates and time constraints imposed by an abundance of stressful thermal environments may result in small home ranges. In Fall, increased temperatures cause higher metabolic rates and allow more time for exploitation of the cooler portions of the home range, hence, home range sizes increase. In the Hot season, there is abundant food and optimal thermal conditions, but home ranges remain large. Searching for preferred foods may cause the large home ranges in this season. 相似文献
76.
This study was designed to explore the question of whether the population of morphologically similar smooth muscle cells (SMC) in the vessel wall is functionally homogeneous or heterogeneous with respect to their proliferative response to injury. Using time-lapse video recording we measured interdivision times (IDT) of primary SMC clones, sibling pairs, and mother/daughter pairs. SMC from in vivo undisturbed vessels displayed an interclonal and intraclonal heterogeneity with a wide range in IDT. In vivo balloon injury resulted in a population with homogeneously short IDT. While 80% of IDT of SMC from injured vessels were shorter than 14 h, only slightly more than half of IDT of cells from undisturbed vessels fell into this category. Longitudinal analysis of mother/daughter pairs confirmed the presence of a heterogeneous population of SMC in the undisturbed vessel wall. In vivo balloon injury not only shortened the IDT of the majority of cells, but the shorter IDT persisted much longer than in the case of the undisturbed vessel. We suggest that a morphologically homogeneous SMC population in the aorta can now be subdivided into several groups of functionally different SMC with respect to their proliferative response to injury. 相似文献
77.
78.
Toshihisa Ohshima Christian Wandrey Miyuki Sugiura Kenji Soda 《Biotechnology letters》1985,7(12):871-876
Summary Screening of leucine and alanine dehydrogenases in thermophilicBacillus strains was carried out to develop their utilization for industrial and analytical catalysts. Out of the 28 thermophilic strains tested, four strains,Bacillus sp. DSM 405, 730 and 1521, andB.
sphaericus DSM 462, abundantly produce both the enzymes. Both the enzyme activities in these thermophiles are enhanced by addition of the substrates to a polypeptone medium. 相似文献
79.
Christian Leuckert 《Plant biology (Stuttgart, Germany)》1985,98(1):401-408
Die Kombination (Koppelung) der Stoffe im Chemosyndrom kann gegenseitig oder einseitig obligat oder auch fakultativ sein. Dabei ist die Stellung der beteiligten eng verwandten Produkte im Rahmen der Biosynthese von Fall zu Fall verschieden. — Dem Chemotaxonomen kann die Berücksichrigung dieser Aspekte zumindest tendenziell als Anhaltspunkt dienen. Bei Vorkommen der Komponenten in verschiedenen Verwandtschaftskreisen wird man ein Chemosyndrom - also eine Kornbination biogenetisch eng verwandter Verbindungen - urn so eher als ein einziges Merkmal betrachten können, je seltener die Kombination aufgelöst ist. Zweifellos stellen der solitare Stoff als Einzelmerkmal und die ohne Ausnahme auftretende (obligate) Kombination als Einzelmerkmal nur Extreme einer gleitenden Reihe dar. Herrn Prof. Dr. E. KLUG (Berlin) danke ich für die Durchsicht des Manuskripts und für werrvolle Diskussion, Herrn H. LÜNSER für die sorgfältige Ausführung der Zeichnungen, Frau I. EGGERT, Frau C. MÜLLER und Frau 1. POHL für die Hilfen bei der Vorbereitung des Manuskripts. Herrn Dr. M. SEAWARD (Bradford) bin ich für Beratung und Diskussion in Zusammenhang mit der Form der englischen Zusammenfassung sehr zu Dank verpflichter, 相似文献
80.
Michel Delarue Thierry Darribere Christian Aimar Jean-Claude Boucaut 《Development genes and evolution》1985,194(5):275-280
Summary Most hybrids betweenBufo bufo andB. calamita obtained by nuclear transplantation become arrested at the early gastrula stage. In both parental controls and the hybrid embryos, the presence and distribution of extracellular matrix was analysed with fluorescent wheat germ agglutinin and by immunolabelling with antibodies directed against fibronectin. InB. bufo andB. calamita gastrulae and in the few hybrids that complete gastrulation, the inner surface of the blastocoel roof is covered by a fibronectin-rich fibrillar matrix. In nucleocytoplasmic hybrids whose development was arrested at the gastrula stage, the fibronectin-containing extracellular matrix was either totally absent or poorly developed and disorganized. 相似文献