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1.
Yeast colonizing the intestine of rainbow trout (Salmo gairdneri) and turbot (Scophtalmus maximus) 总被引:1,自引:0,他引:1
Yeast were isolated from the intestine of farmed rainbow trout (Salmo gairdneri), turbot (Scophtalmus maximus), and free-living flat-fish (Pleuronectes platessa and P. flesus). The average number of viable yeasts recovered from farmed rainbow trout was 3.0 × 103 and 0.5 × 102 cells per gram homogenized intestine for white and red-pigmented yeasts, respectively. The dominant species were Debaryomyces hansenii, Saccharomyces cerevisiae, Rhodotorula rubra, and R. glutinis. In 5 of 10 free-lving marine fish, > 100 viable yeast cells per gram intestinal mucus were recovered. Red-pigmented yeasts dominated and composed >90% of the isolates. Colonization experiments were performed by inoculating rainbow trout and turbot with fish-specific, isolated yeast strains and by examining the microbial intestinal colonization at intervals. Inoculation of experimental fish with pure cultures of R. glutinis and D. hansenii HF1 yielded colonization at a level several orders of magnitude higher than before the inoculation. Up to 3.8 × 104, 3.1 × 106, and 2.3 × 109 viable yeast cells per gram intestine or feces were recovered in three separate colonization experiments. The high level of colonizing yeasts persisted for several weeks. The concentrations of yeasts in the tank water never exceeded 103 viable cells per milliliter. No traces of fish sickness as a result of high yeast colonization were recorded during any of the colonization experiments. For periods of the experiments, the concentration of aerobic bacteria in the fish intestine was lower than the intestinal yeast concentration. Scanning electron microscopy studies demonstrated a close association of the yeasts with the intestinal mucosa. The mucosal colonization was further demonstrated by separating intestinal content, mucus, and tissue. All compartments were colonized by >103 viable yeast cells per gram. No bacteria were detected on the micrographs, indicating that their affinity for the intestinal mucosa was less than that of the yeasts.
Correspondence to: Thomas Andtid 相似文献
2.
LYMPHOCYTE POPULATIONS IN MOUSE BONE MARROW: QUANTITATIVE KINETIC STUDIES IN YOUNG, PUBERTAL AND ADULT C3H MICE 总被引:6,自引:0,他引:6
Continuous 3H-thymidine infusion was used to characterize two kinetic subpopula-tions of small lymphocytes in mouse bone marrow during normal growth and development. Young (4 wk), pubertal (8 wk) and mature (16 wk) C3H mice were infused subcutaneously with 3H-thymidine for periods up to 10 days. Femoral marrow was then examined in radioautographic smears. During the first 3 days the proportion of marrow small lymphocytes labelled by 3H-thymidine showed a rapid exponential increase to 93%, 81% and 72% in 4 wk, 8 wk and 16 wk mice respectively. The rate of appearance of labelled small lymphocytes then declined markedly but remained higher in younger than in older animals. The labelling curves were found to represent the summation of two exponential curves from which the proportions and renewal rate of corresponding cell populations were calculated. Most marrow small lymphocytes comprised a rapidly renewing population but in mice of increasing age the relative incidence of these cells fell (93-3% at 4 wk; 88-0% at 8 wk; 78-5% at 16 wk) and their half-renewal time (T½) lengthened (14 hr at 4 wk; 18 hr at 8 wk; 24 hr at 16 wk). The remaining small lymphocytes were slowly renewing with mean T½ of 4, 7 and 14 days in 4, 8 and 16 wk mice, respectively. Some heavily labelled small lymphocytes persisted in the marrow up to 10 wk after fourteen daily 3H-thymidine injections in 10–12 wk mice. The numbers of rapidly renewing cells decreased from 604 times 103 to 228 times 103 per mm3 of marrow from 4 wk to 16 wk, respectively, while slowly renewing cells increased from 44 times 103 to 61 times 103 per mm3. The total number of nucleated marrow cells per femur increased from 4 wk to 16 wk but the rapidly renewing small lymphocytes per femur fell in numbers by 36% and in renewal rate by 63%. The results demonstrate a selective change in bone marrow small lymphocytes with age; rapidly renewing cells decline in number and renewal rate while the number of slowly renewing cells increases. The concept of bone marrow as a primary lymphoid organ is discussed. 相似文献
3.
Charlene L. Forest 《Experimental cell research》1982,139(2)
The flagella of Chlamydomonas reinhardi are required for the initiation of mating between opposite mating type gametes. It has been suggested that flagellar length is a crucial factor in a cell's ability to transmit and receive the sexual signals necessary for fusion. Mating type + (mt+) cells of gam-5, a mutant which is characterized by variable length, paralyzed flagella, were mated with wild-type, mt− cells. Activation of the mating structures of the gam-5 gametes, and therefore successful signalling, was demonstrated for cells with flagella as short as 1.5 μm (less than 1/6 normal length). Because this mutant displays aberrant axonemal structures, and because various mutants with other defects in axonemal structure are also able to mate, it seems likely that the flagellar membrane may provide the main conduit for gametic sexual signals. 相似文献
4.
Surface-associated algivorous ciliated protozoa are common in the benthos of streams, but little is known about the feeding ecology of these organisms. We compared the functional responses of two algivorous ciliated protozoa, Oxytricha fallax (a filter feeder) and Trithigmostoma cucullulus (an encounter feeder). The ciliates were fed 14C-labeled Navicula cryptocephala in laboratory feeding experiments to determine their potential to consume significant amounts of algal prey. Logistic regression, and plots of the proportion of N. cryptocephala ingested vs. the total number offered, indicated functional responses of a typical rectangular hyperbolic (type II) form for both ciliates. Ingestion rates were estimated from regressions of the number of 14C-labeled N. cryptocephala cells ingested per ciliate vs. time. Maximum feeding rates and half-saturation concentrations were estimated by fitting the observed ingestion rates and experimental algal densities to a function of the Michaelis-Menten enzyme kinetics form using nonlinear regression. For O. fallax, the maximum feeding rate was estimated to be 1.07 N. cryptocephala cells per minute, and the half-saturation concentration was 3.9 × 102 N. cryptocephala per square centimeter. For T. cucullulus the maximum feeding rate was estimated to be 0.2 N. cryptocephala per minute, and the half-saturation concentration was 5.4 × 103
N. cryptocephala per square centimeter. The data were also fitted using only the number of cells ingested at 60 and 120 min, by converting the endpoint consumption to rates. For O. fallax, the estimated maximum feeding rates were 1.3 and 1.0 N. cryptocephala per minute for 60 and 120 min, respectively, and estimated half-saturation concentrations were 5.1 × 102 and 3.5 × 102
N. cryptocephala per square centimeter. For T. cucullulus, estimated maximum feeding rates were 0.6 and 0.4 N. cryptocephala per minute for 60 and 120 min, respectively, and estimated half-saturation concentrations were 1.5 × 104 and 1.1 × 104 N. cryptocephala per square centimeter. These results suggest that kinetic methods for estimating ingestion rates are more accurate than endpoint determinations. Based on field observations of periphyton densities, these ciliates potentially are consuming 4.8% of the total available standing crop of diatom biomass per day and this could represent up to 16% of total available daily primary production. 相似文献
5.
Protein production capabilities ofTrichpolusia ni (TN 368) cells andSpodoptera frugiperda (Sf9) cells were compared in GTC100 medium in suspension culture using as a vector a genetically engineeredAutographa californica nuclear polyhedrosis virus. TN 368 produces more -galactosidase than Sf9, on a per cell basis (2.2×105 and 1.7×105 units/ 106 cells1 respectively). In growth experiments serum-free medium supported a higher maximum Sf9 cell density (4±1×106 cells/ml) than the serum- based media (1.5±5×106 cells/ml in GTC100 and 2±1×106 cells/ml in TNM-FH). However, using a cell density of 5×05 cells/ml, the productivity per cell varied, from a low of 4.5×104 units in EX-CELL-400 medium to a high of 7.6×104 units in TNM-FH. The TN 368 cells were twice a large as Sf9 cells and appeared to be more shear sensitive than Sf9 cells. 相似文献
6.
Six densities (0.5 × 106, 1.0 × 106, 1.5 × 106, 2.0 × 106, 3.0 × 106, and 4.0 × 106 cells ml–1) of the micro-alga Scenedesmus acuminatus, were fed to the cladoceran, Moina micrura, in 40-litre glass aquaria. Moina population increased with increasing cell densities of Scenedesmus only up to treatment 3 (i.e. 1.5 × 106 cells ml–1) where a peak population of 11303 individuals per litre was obtained. Moinapopulation growth was inhibited at higher algal densities. The percentage of egg-bearing females and the number of eggs per egg-bearing females, followed a similar pattern. Comparatively, the peak production density of approximately 11000 Moina per litre, is interesting from a mass production point of view and indicates that S. acuminatus is a satisfactory micro-alga food for M. micrura. 相似文献
7.
Effect of yeast inoculation rate on the metabolism of contaminating lactobacilli during fermentation of corn mash 总被引:1,自引:0,他引:1
Two separate 4 (bacterial concentrations)×6 (yeast concentrations) full factorial experiments were conducted in an attempt to identify a novel approach to minimize the effects caused by bacterial contamination during industrial production of ethanol from corn. Lactobacillus plantarum and Lactobacillus paracasei, commonly occurring bacterial contaminants in ethanol plants, were used in separate fermentation experiments conducted in duplicate using an industrial strain of Saccharomyces cerevisiae, Allyeast Superstart. Bacterial concentrations were 0, 1×106, 1×107 and 1×108 cells/ml mash. Yeast concentrations were 0, 1×106, 1×107, 2×107, 3×107, and 4×107 cells/ml mash. An increased yeast inoculation rate of 3×107 cells/ml resulted in a greater than 80% decrease (P<0.001) and a greater than 55% decrease (P<0.001) in lactic acid production by L. plantarum and L. paracasei, respectively, when mash was infected with 1×108 lactobacilli/ml. No differences (P>0.25) were observed in the final ethanol concentration produced by yeast at any of the inoculation rates studied, in the absence of lactobacilli. However, when the mash was infected with 1×107 or 1×108 lactobacilli/ml, a reduction of 0.7–0.9% v/v (P<0.005) and a reduction of 0.4–0.6% v/v (P<0.005) in the final ethanol produced was observed in mashes inoculated with 1×106 and 1×107 yeast cells/ml, respectively. At higher yeast inoculation rates of 3×107 or 4×107 cells/ml, no differences (P>0.35) were observed in the final ethanol produced even when the mash was infected with 1×108 lactobacilli/ml. The increase in ethanol corresponded to the reduction in lactic acid production by lactobacilli. This suggests that using an inoculation rate of 3×107 yeast cells/ml reduces the growth and metabolism of contaminating lactic bacteria significantly, which results in reduced lactic acid production and a concomitant increase in ethanol production by yeast. 相似文献
8.
Summary In exponentially growing cultures of the blue-green alga Microcystis aeruginosa the number of gas vacuoles per cell decreases and reaches a value of 4.5×103 at 1.2×107 cells per ml. The assembly of gas vacuoles with respect to number and length was followed after the organelles were caused to collapse by a pulse of ultrasound. The change in the number N of gas vacuoles per cell is N=224.8×t
0.757, 0<t<24 h. After 24 h 50% of the value of non-sonicated cultures is reached. The changes in the length L of the organelles is expressed by L=87.06 ×t
0.4084, 0<t<24 h. After 24 h 85% of the control value is reached.Abbreviations used EDTA
ethylene diamine tetraacetate
- BSA
bovine serum albumine
-
P
probability
-
N
number of gas vacuoles
-
L
length of gas vacuoles in nm
-
t
time in hours 相似文献
9.
Strains of Staphylococcus aureus, an opportunistic pathogen commonly found on human skin, were exposed to sunlight and UV C radiation, and the lethal and mutational effects measured. Sunlight killed cells with an inactivation constant of 3×10-5 per joule per square metre; UV C was much more lethal, giving an inactivation constant of approximately 0.1 per joule per square metre. Some strains tested showed a sensitivity to sunlight that was dependent on the growth phase of the cells, exponentially growing cells showing a greater sensitivity. Mutational effects of irradiation were measured by the appearance of mutants sensitive to methicillin following irradiation of a multiresistant strain. Mutants appeared at a frequency of 10-3; this high frequency of mutation in the region of the mec gene has also been observed when multiresistant strains are subjected to nutritional or thermal stress. Mutants showed the same chromosomal alteration (seen in pulse-field gel electrophoresis of Smal-digested DNA) whether induced by solar or UV C irradiation. 相似文献
10.
G. K. KINOTI 《African Journal of Ecology》1973,11(2):129-134
Observations are reported on the composition of the blood of a tropical, cave-dwelling bat, Otomops martiensseni. The most remarkable feature of the blood was the very high numbers of erythrocytes, with mean values of 14–42 times 106 and 12–46 times 106 cells per mm3 of blood, for female and male bats respectively. The red cells were spherical, biconcave discs with a mean diameter of 5-3 um, a mean thickness of 1–8 urn and a mean volume of 40-7 μm3. High haemoglobin values were obtained, with means of 20–70 and 18-15 g per 100 ml of blood, for female and male bats respectively. The leucocyte count varied from 1360 to 5200 cells per mm3 of blood and was rather lower than in other mammals. Electrophoresis of serum gave six protein fractions which were identified as albumin and α1α2, β1β2 and γ globulins. 相似文献
11.
E. S. Jensen 《Plant and Soil》1987,97(1):63-70
Summary Selected streptomycin resistant strains ofRhizobium leguminosarum suspended in nutrient broth were added to the planting furrow immediately before the sowing of pea. The nodule occupancy by a strain isolated from Risø soil (Risø la) was increased from 74 to 90%, when the inoculum rate was increased from 3.7×106 to 3.7×108 cells per cm row. The experimental soil contained 103 to 104 cells ofR. leguminosarum per gram. An almost inefficient strain isolated from Risø soil (SV10) was less competitive with respect to nodulation on two pea cultivars than an efficient Risø strain (SV15) and an efficient non-Risø strain (R1045). The nodule occupancy by the introduced strains varied between pea cultivars.Irrespective of the generally high nodulation by the efficient strains introduced to the soil, the pea seed yield, compared to pea nodulated by the indigenous population, was not significantly increased. Neither were two commercial inoculants, applied in rates corresponding to 3 times the recommended rate, able to increase the yield. This suggests that the indigenous populations ofR. leguminosarum were sufficient in number and nitrogen fixing capacity to ensure an optimal pea crop. However, some inoculation treatments slightly increased the seed N concentration and total N accumulation, indicating that it may be possible to select or develop bacterial strains that may increase the yield. 相似文献
12.
Actin cytoskeleton in intact and wounded coenocytic green algae 总被引:5,自引:0,他引:5
J. W. La Claire II 《Planta》1989,177(1):47-57
Summary The subcellular distribution of actin was investigated in two related species of coenocytic green algae, with immunofluorescence microscopy. Either no, or fine punctate fluorescence was detected in intact cells of Ernodesmis verticillata (Kützing) Børgesen and Boergesenia forbesii (Harvey) Feldmann. A reticulate pattern of fluorescence appears throughout the cortical cytoplasm of Ernodesmis cells shortly after wounding; this silhouettes chloroplasts and small vacuoles. Slender, longitudinal bundles of actin become evident in contracting regions of the cell, superimposed over the reticulum. Thicker portions of the bundles were observed in well-contracted regions, and the highly-convoluted appearance of nearby cortical microtubules indicates contraction of the bundles in these thicker areas. Bundles are no longer evident after healing; only the reticulum remains. In Boergesenia, a wider-mesh reticulum of actin develops in the cortex of wounded cells, which widens further as contractions continue. Cells wounded in Ca2+-free medium do not contract, and although the actin reticulum is apparent, no actin bundles were ever observed in these cells. Exogenously applied cytochalasins have no effect on contractions of cut cells or extruded cytoplasm, and normal actin-bundle formation occurs in treated cells. In contrast, erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA) completely inhibits longitudinal contractions in wounded cells, and few uniformly slender actin bundles develop in inhibited cells. These results indicate that wounding stimulates a Ca2+-dependent, hierarchical assembly of actin into bundles, whose assembly and functioning are inhibited by EHNA. Contraction of the bundles and concomitant wound healing are followed by cessation of motility and disassembly of the bundles. The spatial and temporal association of the bundles with regions of cytoplasmic contraction, indicates that the actin bundles are directly involved in wound-induced cytoplasmic motility in these algae.Abbreviations EHNA
erythro-9-[3-(2-hydroxynonyl)]adenine
- MT(s)
microtubule(s) 相似文献
13.
In vitro adherence of the nosocomial pathogensPseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, andCandida albicans to select radiopaque silicone compounds was lower than that observed for the base silicone (p<0.03). Except forE. coli ATCC 11775 andCandida albicans, all microorganisms showed significantly lower adherence to a silicone compound impregnated with tantalum in comparison with a silicone compound impregnated with barium sulfate (p<0.05). Surface hydrophobicity of the silicone compounds did not show a direct correlation with the concentration of radiopacity additives or with degree of bacterial adherence. Scatchard analyses of data indicated that the number of adherence sites forP. aeruginosa on the base silicone, BaSO4-silicone, and Ta-silicone were 9.2×106 per mm2, 6.1×106 per mm2, and 3.7×106 per mm2 respectively. As determined by the Langmuir adsorption isotherm, the dissociation constants for adheredP. aeruginosa to the base silicone, BaSO4-silicone, and Ta-silicone were 2.50×103 mm4, 1.45×103 mm4, and 6.27×103 mm4 respectively.Pseudomonas aeruginosa demonstrated first order kinetics of adherence to the silicone compounds with a half saturation time of 4.15 h for the base silicone, 1.06 h for the BaSO4-silicone, and 2.14 h for the Ta-silicone. The use of Ta-silicone stents may delay the development of ascending urinary tract infections. 相似文献
14.
A. N. Dzyuban 《Microbiology》2005,74(1):104-110
The cell numbers and ecological characteristics of the distribution of certain species of butyric acid bacteria (BABs) of the genus Clostridium in the bottom sediments of inland basins of different types were studied using the optimal nutrient media. The seasonal dynamics of clostridial vegetative cells and spores in sediments with different ecological conditions were revealed. The cell numbers of the dominant BAB species were shown to depend on the redox potential of the sediments, the amount and composition of Corg, and the trophic state of the basin in general. C. pasteurianum was found to predominate in eutrophic lakes and reservoirs (5–11 × 106 cells/cm3), C. butyricum and C. felsineum predominated in mesotrophic ones (2–11 × 106 cells/cm3), and C. acetobutylicum was predominant in acidic chthonioeutrophic lakes and reservoirs (0.1–0.5 × 106 cells/cm3). The lowest cell numbers of BABs were found in river sediments, whereas the highest numbers were recorded in the sediments of polysaprobic zones (0.1–1.0 × 103 and 0.5–2.0 × 107 cells/cm3 respectively).Translated from Mikrobiologiya, Vol. 74, No. 1, 2005, pp. 119–125.Original Russian Text Copyright © 2005 by Dzyuban. 相似文献
15.
Perfused cell segments dissected from the stalk or from detached cap ray chambers of Acetabularia were used as an experimental system to study the induction of cytoplasmic contractions and concurrent cytoskeletal changes in plant cells. Immunofluorescence microscopy revealed that the actin cytoskeleton quickly rearranges upon induction of contraction by forming bundles oriented circumferentially around the affected area, whereas microtubules were not detected. Contraction is blocked by cytochalasin D or N-ethylmaleimide but is unaffected by microtubule specific inhibitors. Contraction requires external Ca2+ at concentrations of 1 μM or more, but fails to occur below 0.1 μM. Higher concentrations of Ca2+ up to 10 mM have no adverse effect. Contraction is prevented in the presence of micromolar Ca2+ by either 1 mM of the calcium channel blocker LaCl3 or 10 μM of the calmodulin inhibitor fluphenazine. Calcium ionophore A 23187 (1 μM) does not perturb wound contraction per se but causes the entire cytoplasm of wounded or unwounded cells to contract slowly. These data suggest that a localized influx of calcium ions at the wound edge causes major rearrangements in the distribution of cytoskeletal actin prior to contraction in Acetabularia. An involvement of calmodulin in calcium signaling is proposed. 相似文献
16.
Stomatal movement in Zea mays: Shuttle of potassium and chloride between guard cells and subsidiary cells 总被引:2,自引:2,他引:0
Summary When stomates of Zea mays open K and Cl migrate from the subsidiary cells into the guard cells; when the stomates close both elements return to the subsidiary cells. Subsidiary cells function as reservoirs for K and Cl. Import of K and Cl into the guard cells and loss of both elements from the guard cells become observable 1 or 2 min after light is turned on or off, both when histochemical methods and the electron-probe microanalyzer are used for detection. Each stomatal complex of maize contains on the average 10±3×10-13 gram equivalents (eq) of K and 4±1×10-13 eq of Cl. Guard cells accumulate K in the light and CO2-free air at an average rate of 10×10-15 eq K per minute, and Cl at approximately half that rate. 相似文献
17.
Life table demography and population growth of Brachionus variabilis Hempel, 1896 in relation to Chlorella vulgaris densities 总被引:4,自引:0,他引:4
We studied the life history variables and population growth characteristics of Brachionus variabilis, which was recorded for the first time from Mexico. The animals were fed Chlorella, using five concentrations (0.25, 0.5, 1, 2 and 4 × 106 cells ml–1) at 25 °C. Food density was observed to have significant effect on life expectancy, average lifespan, gross reproductive rate, net reproductive rate, generation time and population growth rate. The average lifespan ranged from 3 to 6 days depending on the food density. The net reproductive rate ranged from 2 to 7 neonates female–1 d–1. The rate of population increase per day varied from 0.14 to 0.35. The highest net reproductive rate and average lifespan and life expectancy were recorded at Chlorella concentrations of 1 × 106 and 2 × 106 cells ml–1. 相似文献
18.
Although fibroblastic cultures from the skin of both non-diabetic and diabetic (db/db) mice have specific receptors for insulin, cells from diabetic mice bind only half as much insulin as those from non-diabetic animals. Treatment of cultures from non-diabetic and diabetic mice with trypsin caused an increase in the total number of binding sites from 7.7 × 104 to 11.0 × 104 per cell in nondiabetic and from 2.9 × 104 to 5.1 × 104 per cell in diabetic cells. The increase is reversible and apparently specific for trypsin. Cells cultured from non-diabetic and diabetic animals are flat and fusiform and have microfilaments of various sizes occurring individually in the cytoplasm and in bundles running parallel with the plasma membrane. Trypsin treatment causes rounding of cells, with development of numerous blebs and folds, and depolymerization and disappearance of microfilament bundles in both non-diabetic and diabetic cells. The present study demonstrates that although diabetic fibroblasts have fewer insulin receptors than cells from non-diabetic littermates, the effects of trypsin on insulin receptors, organization of macrofilament bundles, and cell morphology have not been altered by the expression of the diabetic state. 相似文献
19.
Competent cells of Bacillus subtilis were transformed with DNA from gently lysed protoplasts. Significant linkages among markers separated by distances of approximately 2.3% of the total chromosome were found, which have not been detected for conventional transformation. In comparison to previous reports, enhanced plasmid transformation was observed [4.0×107 transformants per g DNA (one transformant per 5×104 molecules added)], when competent cells were transformed with DNA from lysed protoplasts harboring pUB110. 相似文献
20.
The contribution of ciliates as a food source to survival of first-feeding surgeonfish larvae, Paracanthurus hepatus, was examined in rearing experiments. The larvae were exposed to eight treatments; i.e. a tintinnid, Amphorellopsis acuta (1.0 × 104, 5.1 × 103 and 2.2 × 103 cells l–1) and a naked ciliate, Euplotes sp. (1.3 × 104, 8.0 × 103 and 5.0 × 103 cells l–1), plus two controls without ciliates. Highest survival of the larvae over the first 4–8 days was observed in the highest density of A. acuta. Rearing experiments also showed that the survivals of larvae fed with A. acuta were higher than those fed with Euplotes sp. Gut content analyses revealed loricae of A. acuta in the larvae. Although Euplotes sp. (lacking loricae) was never recognized in those larval guts, feeding on Euplotes sp. by larvae was confirmed using the ciliate labeled with fluorescent microspheres, implying that the feeding on naked ciliates by fish larvae has been overlooked. The results strongly suggested that both tintinnid and naked ciliates play important roles as alternative food sources to copepod nauplii by enhancing the survivability of fish larvae, especially those with a smaller mouth. 相似文献