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91.
Microtubules Orient the Mitotic Spindle in Yeast through Dynein-dependent Interactions with the Cell Cortex 总被引:31,自引:9,他引:22
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Proper orientation of the mitotic spindle is critical for successful cell division in budding yeast. To investigate the mechanism of spindle orientation, we used a green fluorescent protein (GFP)–tubulin fusion protein to observe microtubules in living yeast cells. GFP–tubulin is incorporated into microtubules, allowing visualization of both cytoplasmic and spindle microtubules, and does not interfere with normal microtubule function. Microtubules in yeast cells exhibit dynamic instability, although they grow and shrink more slowly than microtubules in animal cells. The dynamic properties of yeast microtubules are modulated during the cell cycle. The behavior of cytoplasmic microtubules revealed distinct interactions with the cell cortex that result in associated spindle movement and orientation. Dynein-mutant cells had defects in these cortical interactions, resulting in misoriented spindles. In addition, microtubule dynamics were altered in the absence of dynein. These results indicate that microtubules and dynein interact to produce dynamic cortical interactions, and that these interactions result in the force driving spindle orientation. 相似文献
92.
The complete nucleotide sequence of the chloroplast genome of the red algaPorphyra purpurea has been determined (accession number=U38804). The circular genome is 191,028 bp in length and encodes approximately 250
genes. 相似文献
93.
94.
Soft rot Erwinia bacteria in surface and underground waters in southern Scotland and in Colorado, United States 总被引:7,自引:6,他引:1
Nancy J. McCarter-Zorner G.D. Franc M.D. Harrison Janet E. Michaud C.E. Quinn I. Ann Sells D.C. Graham 《Journal of applied microbiology》1984,57(1):95-105
An anaerobic liquid enrichment method followed by plating on a selective medium revealed that the soft rot coliform bacterium Erwinia carotovora subsp. carotovora was generally present in water from drains, ditches, streams, rivers and lakes (including reservoirs) in southern Scotland and in Colorado, United States, in mountainous, upland and arable areas through the year. Many sites were remote from susceptible or diseased crops. Erwinia carotovora subsp. atroseptica was isolated much less frequently and no Erwinia bacteria were isolated from underground waters. Erwinia bacteria were also found in rain-water in Scotland, in winter snow from mountain passes in Colorado, and in sea water from the west and east coasts of Scotland and from the coasts of Oregon, California, Texas, Louisiana and Florida. The significance of the occurrence of these bacteria in water is discussed in relation to the control of blackleg and soft rot diseases of potato by production of Erwinia -free stocks. 相似文献
95.
96.
Janet Silnutzer David W. Barnes 《Biochemical and biophysical research communications》1984,118(1):339-343
Purified human serum spreading factor preparations consisting of two immunologically-related, biologically-active proteins of molecular weights approximately 65,000 and 75,000 were incubated with purified hydrolytic enzymes: papain, neuraminidase and thrombin. Biologically active products of the enzymatic digestions were obtained in each case. Digestion of serum spreading factor preparations with thrombin produced a single active form of molecular weight approximately 57,000. Generation of a single molecular weight form of serum spreading factor by thrombin cleavage of the two higher molecular weight forms should simplify studies of the biochemistry and biology of this protein, and may represent a reaction of physiological significance. 相似文献
97.
Nutrient cycling and biomass characteristics of a tropical palm forest dominated byOrbignya cohune were found to be different from thsoe of hardwood dominated forests. The cohune palm forest had a high proportion of biomass in leaves (5%), a reduced sapling layer, a large amount of standing forest litter and an exceptionally low decomposition rate factor (0.1 year–1). Mineral concentrations in palm leaves were generally lower than in hardwood species with the exception of Na, which was exceptionally high inOrbignya cohune. Biomass was estimated at 226 tons ha–1 containing 1173 kg ha–1 N; 126 kg ha–1 P; 437 kg ha–1 K; 1869 kg ha–1 Mg; 125 kg ha–1 Ca, and 2177 kg ha–1 Na. Soils of cohune association did not differ significantly from those of neighbouring hardwood dominated associations with the exception of Na which occurred in higher concentration because of bioaccumulation in the dominant. The results suggest that the growth habits and physiology of a dominant can strongly influence some of the ecological parameters used to describe aforest association. 相似文献
98.
CONCENTRATIONS OF ENERGY METABOLITES AND CYCLIC NUCLEOTIDES DURING AND AFTER BILATERAL ISCHEMIA IN THE GERBIL CEREBRAL CORTEX 总被引:2,自引:0,他引:2
Abstract— The concentrations of metabolites which reflect energy production or use ( P -creatine, ATP. ADP. 5'AMP, glucose, glycogen and lactate) and cyclic nucleotides (cyclic AMP and cyclic GMP) were measured in gerbil cortex during ischemia and recirculation. Bilateral ischemia of the gerbil brain was chosen as a model to ensure the assessment of short periods of ischemia without ambiguity. The metabolites and cyclic nucleotides were measured after, 1, 5. 20. 30 and 60 min of ischemia; and 1, 5, 30, 60 and 360 min after circulation was reestablished. The greatest changes in metabolites and cyclic nucleotides due to ischemia occurred during the 1st min; ischemia of longer duration had little further effect. However, the restoration of the metabolic profile was altered by the duration of the ischemic period. In general, the longer the period of ischemia, the slower the replenishment of high-energy phosphate compounds and energy sources. Cyclic AMP increased 5- to 13-fold during ischemia; cyclic GMP decreased to as little as one-fifth control values 60min after occlusion. During recirculation, cyclic AMP increased as much as 100-fold, while cyclic GMP increased up to 6-fold. The temporal derangements in cyclic nucleotide concentrations coincide with the loss and restoration of cortical activity; a possible mechanism has been suggested. 相似文献
99.
Summary A patient with acute lymphoblastic leukemia (ALL) whose cells had L3 (Burkitt-type) morphology was found to have a variant translocation t(2;8)(p13;q24), that has been reported only in Burkitt lymphomas. This observation provides additional evidence for a close association of particular karyotypic abnormalities with both Burkitt-type ALL and Burkitt lymphoma. 相似文献
100.
Summary Reticulum cell sarcoma (RCS) cells of SJL/J (H-2s) mice have been shown to express antigens that are cross-reactive with allogeneic cells of the H-2d and H-2b haplotypes by cell-mediated cytotoxicity, antibody-mediated cytotoxicity, immunofluorescence, and quantitative absorption assays. These alien antigens have been detected on both spontaneous and in vivo- and in vitro-passaged RCS cells to varying degrees.The in vitro cell lines were able to stimulate a syngeneic cytotoxic T cell response detected in a 4-h 51Cr release assay. The cytotoxic cells reacted with in vitro RCS tumor targets but not with in vivo or spontaneous RCS tumors. Furthermore, the cytotoxic cells lysed H-2d and to a lesser extent H-2b target cells, but not H-2k, H-2p, or H-2r cells. The cross-reactivity was also observed with SJL/J anti-BALB/c cytotoxic cells, which can lyse in vitro RCS targets effectively. The in vivo tumors were not stimulatory in cytotoxic responses and did not serve as targets.H-2d specificities were also detected in cultured RCS tumor cells by cytotoxic antibody. Both allogeneic SJL/J anti-BALB/c, C57B1/6 anti-BALB/c sera reacted with RCS tumor cells and not normal SJL/J cells. Furthermore, monospecific Dd sera were also cytotoxic against RCS lines. The cytotoxic activity could be absorbed by BALB/c cells and RCS cells but not with normal SJL/J cells. The H-2d specificities were also detected on the in vivo lines by indirect immunofluorescence. The majority (60%) of spontaneously arising tumors expressed either H-2d or H-2b allospecificities in the immunofluorescence assays. Although these antigens may not be inappropriate for the SJL/J strain, their differential expression on tumor cells may be significant in the etiology of the tumor. 相似文献