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71.
Examination of Genetic Relatedness of Marine Synechococcus spp. by Using Restriction Fragment Length Polymorphisms 总被引:3,自引:3,他引:0
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The relatedness of several marine Synechococcus spp. was estimated by DNA hybridization. Strains isolated from various geographical locations and representing a diversity of DNA base compositions and phycobiliprotein profiles were compared by restriction fragment length polymorphisms for a number of genes. DNAs from two marine red algae and a cryptomonad alga (which exhibit a phycobiliprotein composition similar to that of the marine Synechococcus spp.) and Synechococcus strain PCC6301 (Anacystis nidulans) were also included in the comparison. Strains WH8008, WH8018, and WH7805 were shown to be very similar to one another, as were strains WH7802 and WH7803. Strains WH8110 and WH5701 were clearly unrelated to any of the other strains, and no marine Synechococcus isolate showed any similarity to the freshwater Synechococcus strain PCC6301 or the eucaryotic algae. The method is relatively straightforward and sensitive and uses a variety of basic molecular biology techniques. Its utility in ascertaining the genetic relatedness and diversity of marine Synechococcus spp. and possible extension to field studies are discussed. 相似文献
72.
Rhizobium trifolii 0403 Is Capable of Growth in the Absence of Combined Nitrogen 总被引:1,自引:1,他引:0
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Rhizobium trifolii 0403 was treated with 16.6 mM succinate and other nutrients and thereby induced to grow in nitrogen-free medium. The organism grew microaerophilically on either semisolid or liquid medium, fixing atmospheric nitrogen to meet metabolic needs. Nitrogen fixation was measured via 15N incorporation (18% 15N enrichment in 1.5 doublings) and acetylene reduction. Nitrogen-fixing cells had a Km for acetylene of 0.07 atm (ca. 7.09 kPa), required about 3% oxygen for optimum growth in liquid medium, and showed a maximal specific activity of 5 nmol of acetylene reduced per min per mg of protein at 0.04 atm (ca. 4.05 kPa) of acetylene. The doubling time on N-free liquid medium ranged from 1 to 5 days, depending on oxygen tension, with an optimum temperature for growth of about 30°C. Nodulation of white clover by the cultures showing in vitro nitrogenase activity indicates that at least part of the population maintained identity with wild-type strain 0403. 相似文献
73.
Philip Skehan James E. Thomas Susan J. Friedman 《In vitro cellular & developmental biology. Plant》1986,22(11):632-636
Summary Sarcoma 180 monolayers spontaneously shed single cells and small multicellular aggregates into the surrounding medium to produce
a dual population of floating and substratum-attached cells. Shedding was a motility-associated event that occurred when cells
attempted to migrate over one another. It resulted from a combination of cell shape change and active motility, which increased
sensitivity to fluid shear dislodgement by reducing a cell's surface area of adhesive contact and increasing strain tension
at its adhesive contact points. Shedding occurred at all phases of the cell cycle. Extracellular matrix but not conditioned
medium enhanced the floating subpopulation by slowing the kinetics of rattachment to plastic and cellular substrata. Although
sarcoma 180 cells are anchorage independent in the sense that they grow readily in single cell suspension, they nevertheless
exhibited anchorage modulation of their cell cycle. Short periods in suspension produced a mild G1 accumulation, whereas longer periods of anchorage deprivation led to a mild G2 accumulation which appeared to result from an interference with cytokinesis.
This work was supported by grants from the Medical Research Council of Canada, The National Cancer Institute of Canada, the
Alberta Heritage Savings and Trust Fund for Applied Cancer Research, and the Alberta Heritage Fund for Medical Research. 相似文献
74.
Effect of Metal-Rich Sewage Sludge Application on the Bacterial Communities of Grasslands 总被引:9,自引:7,他引:2
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The effect of long-term application of heavy metal-laden sewage sludge on the total heterotrophic aerobic and the cadmium-resistant soil bacterial communities was studied. Gram-positive bacteria were completely absent from resistant communities. These findings suggest that this group is highly susceptible to Cd. Shannon's diversity indices estimated for total communities did not reveal negative effects on the communities that developed in the presence of sludge. However, Cd-resistant communities isolated from long-term sludge-amended soils were more diverse than the resistant communities from a control sample, suggesting that adaptation to Cd as a stressor had occurred in the presence of sludge constituents. This higher diversity was attributed to Cd resistance in pseudomonads and gram-negative fermenters. Resistance did not develop by dissemination of Cd resistance plasmids, because these were rarely detected in the genomes of resistant strains. 相似文献
75.
Phylogenetic Survey of Proteins Related to Synapsin I and Biochemical Analysis of Four Such Proteins from Fish Brain 总被引:1,自引:1,他引:0
A phylogenetic survey of proteins immunologically related to Synapsin I, a major synaptic vesicle-associated phosphoprotein in mammals was carried out. Proteins antigenically related to Synapsin I were found by use of radioimmunoassay and other radioimmunochemical techniques in the nervous systems of several vertebrate and invertebrate species, which included birds, reptiles, amphibians, fish, echinoderms, arthropods, and mollusks. Four proteins present in fish brain, antigenically related to Synapsin I, were further studied and found to resemble mammalian Synapsin I in several respects. Like Synapsin I, the fish proteins were present in high amounts in nervous tissue, were enriched in synaptosomal fractions of brain where they were substrates for endogenous protein kinases, were acid extractable, and were sensitive to digestion by collagenase. In addition, two-dimensional peptide-mapping analysis revealed some homology between major phosphopeptide fragments of Synapsin I and the fish proteins. The results indicate that proteins related to Synapsin I are wide-spread in the animal kingdom. 相似文献
76.
This communication reports the DNA level identification of class I and class II sequences associated with 20 RT1 haplotypes which have been assigned previously to eight RT1 groups. Sixteen to 22 bands in genomic blots hybridized with the mouse pH-2III class I cDNA probe. Only the three RT1
khaplotypes associated with identical class I restriction fragment patterns. Differences in restriction bands between putatively identical RT1 haplotypes were either less than or equal to 6%, or greater than 50%, suggesting a relatively high level of recombination between serologically identified RT1.A genes and the majority of class I sequences. Restriction fragment patterns associated with three RT1
uhaplotypes differed by less than 6%. However, intra-RT1
a,intra-RT1
b,and intra-RT1
lrestriction fragment differences were between 50 and 64%. In specific cases, different RT1 haplotypes associated with identical class I restriction patterns, e.g., RT1
m(MNR) and RT1
d(MR); higher resolution confirmed the difference (two bands) between RT1
mand RT1
d.Results of hybridization with the human DC1
probe confirmed that the AVN RT1
aand NSD RT1
bhaplotypes were generated by recombinations within the vicinity of the RT1.B : RT1.D regions. These results demonstrate that a previous classification of RT1 haplotypes was incomplete and did not include the majority of class I and class II sequences which distinguish RT1 haplotypes. 相似文献
77.
Philip Skehan Susan J. Friedman 《In vitro cellular & developmental biology. Plant》1985,21(5):288-290
Summary A rapid method has been developed for measuring the cellular protein content of mono- and multilayered anchorage cultures.
Fixed or air dried cultures are stained for 30 min with 0.2% Naphthol Yellow S (NYS) dissolved in 1% acetic acid. Unbound
dye is removed by a series of four 2.5 min washes in 1% acetic acid, and protein-bound dye extracted with 10 mM unbuffered Tris base for spectrophotometric optical density determination at 433 nm. The NYS method exhibited a least-squares
correlation coefficient of 0.99997 with the Oyama-Eagle Lowry method. 相似文献
78.
Dr. Edward B. Blanchard James Jaccard Frank Andrasik Patricia Guarnieri Susan E. Jurish 《Applied psychophysiology and biofeedback》1985,10(1):63-68
Comparisons are made of self-reported medical costs from a sample of headache patients who underwent various combinations of relaxation training and biofeedback training. The average costs for the 2 years prior to self-regulatory treatment were $955±480 (3 SEM) for 45 patients; for the 2 years after completing treatment the average costs were $52±28 (3 SEM) for patients. Within the limitations of the study, medical costs do seem to have been markedly reduced.This research was supported by a grant from NINCDS, NS-15235. 相似文献
79.
M inney , S.F., P arkes , R.J. & B ull , A.T. 1985. A note on the characterization of an estuarine microbial community enriched with the herbicide Fenuron. Journal of Applied Bacteriology 59 , 17—22.
A stable, five-membered estuarine microbial community was enriched in the presence of 1,1 dimethyl-3-phenylurea (Fenuron), phenylurea and aniline. At a dilution rate of 0μD01/h in the chemostat, partial aniline utilization occurred and the rate increased with dilution rate. At the higher dilution rates the phenylurea component was also utilized. At a dilution rate of mD015/h in a fluidized bed system, complete removal of both aniline and phenylurea occurred. There was no evidence of Fenuron degradation under any of the conditions examined. The importance of the use of heterogeneous culture conditions in the laboratory is discussed. 相似文献
A stable, five-membered estuarine microbial community was enriched in the presence of 1,1 dimethyl-3-phenylurea (Fenuron), phenylurea and aniline. At a dilution rate of 0μD01/h in the chemostat, partial aniline utilization occurred and the rate increased with dilution rate. At the higher dilution rates the phenylurea component was also utilized. At a dilution rate of mD015/h in a fluidized bed system, complete removal of both aniline and phenylurea occurred. There was no evidence of Fenuron degradation under any of the conditions examined. The importance of the use of heterogeneous culture conditions in the laboratory is discussed. 相似文献
80.
We estimated age at attainment of sexual maturity and examined reproductive seasonality for male spotted dolphins, Stenella attenuata , from the eastern tropical Pacific Ocean. Maturity was determined by histological examination of testes. Average age at sexual maturation was 14.7 yr (the mean of two readers' age estimates). Testis and epididymis weight and seminiferous tubule diameters were reliable indicators of maturity, whereas age, length and color phase were less reliable. Seasonality was determined by changes in testis and epididymis weight, relative quantity of spermatids and spermatozoa, and lumen diameter, as well as an index of testis development (weight of the right testis and epididymis divided by length of the right testis). Testis and epididymis weights and index values peaked in July and August, midway between two predicted mating seasons for the northern offshore stock, but spermatozoa levels were elevated during the predicted breeding seasons. 相似文献