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1.
The relationship between protein synthesis and the incorporation of [3H]gibberellin A1 ([3H]GA1) into a 2,000xg pelletable (2KP) fraction from lettuce (Lactuca sativa L.) hypocotyl sections has been investigated. Concentrations of D-2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide (MDMP) between 10-7 M and 10-4 M caused increasing inhibition of growth, 2KP labelling and incorporation of [14C]leucine into soluble protein. Growth and 2KP radioactivity were highly correlated (r=0.996). Transfer to MDMP early or late in the course of GA response caused reductions in both growth and incorporation into the 2KP fraction. Exposure to the inhibitor had more effect at 4 h than at 20 h. The proportions of alkali-soluble and insoluble radioactivity in the 2KP fraction were also altered by this treatment. The implications of these findings are discussed.Abbreviations GA1
gibberellin A1
- MDMP
D-2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide
- 2KP
a2,000xg pelletable fraction 相似文献
2.
Summary The pathogenesis ofPseudomonas aeruginosa for the respiratory tract has been examined using hamster tracheal organ cultures. Tracheal rings prepared from male Syrian
hamsters, strain LSH/LAK, were infected withP. aeruginosa for 4 h and processed at 4-h intervals for 24 h for examination by light- and electron microscopy. Tissue destruction was
observed within 8 h after infection with 108 colony-forming units (cfu)/ml and within 12 h after infection with 104 or 106 cfu/ml. Ciliated cells that contained abnormal subcellular organelles were expelled from the epithelium. By 20 h the epithelial
borders were composed primarily of nonciliated cells. Transmission- and scanning electron microscopy revealed details of the
cellular destruction and attachment ofP. aeruginosa to the ciliated epithelium.Pseudomonas aeruginosa causes a rapid destruction of the epithelium of hamster trachea in cultures. Hamster tracheal organ cultures have been shown
to be useful in studying the pathogenesis ofP. aeruginosa for the respiratory tract.
This work was supported by Grants G-430B and G-431B from the Cystic Fibrosis Foundation. 相似文献
3.
Inclusion of IAA in the vase water had little effect on leaf yellowing in cut flowering branches of Alstroemeria pelegrina L. while kinetin delayed leaf yellowing at 10-4M (continuous treatment). Chlorophyll was effectively retained by 10-7M gibberellic acid (GA) in the vase water or by a 20h pulse at 5°C with 10-5/10-4M GA. After 16h of 14C-GA, uptake at 20°C relatively high levels of 14C were found in leaves and low levels in stems and flowers. After this treatment about half of the 14C-GA, in leaves was metabolized into unknown compounds.
Corrigendum. Owing to an error in the proofreading process, the article was published incorrectly. The article as it should have been published is presented here. 相似文献
4.
C. Wacher A. Cañas P. E. Cook E. Barzana J. D. Owens 《World journal of microbiology & biotechnology》1993,9(2):269-274
Freshly prepared pozol, a traditional Mexican fermented maize dough, contained (c.f.u./g wet wt): lactic acid bacteria, 104 to 106; aerobic mesophiles, 104 to 105; Enterobacteriaceae, 102 to 103; yeasts, 102 to 104; and mould propagules, <103. After 30 h at 28°C the numbers were, respectively: 109, 7×106, 5×105, 106 and 104. Soaking alkali-treated grains overnight allowed lactic acid bacteria, aerobic mesophiles and Enterobacteriaceae to grow and these then constituted the primary microbial flora of the pozol dough. Grinding in a commercial mill inoculated the dough with lactic acid bacteria, aerobic mesophiles, Enterobacteriaceae and yeasts. Other processing stages, including the nature of the surface upon which the balls were made, handling of the dough, and air, contributed only minor numbers of microbes compared with the two major sources, soaking and grinding. The pH of pozol fell from an initial value of 7.3 to 4.6 after 30 h incubation at 28°C. The numbers of Enterobacteriaceae and other aerobic mesophilic bacteria remained constant between 11 and 30 h incubation and there was no evidence of the acidic conditions having any lethal effects on these organisms. 相似文献
5.
Inclusion of IAA in the vase water had little effect on leaf yellowing in cut flowering branches of Alstroemeria pelegrina L. while kinetin delayed leaf yellowing at 10–4M (continuous treatment). Chlorophyll was effectively retained by 10–7M gibberellic acid (GA) in the vase water or by a 20h pulse at 5°C with 10–5/10–4M GA. After 16h of 14C-GA3 uptake at 20°C relatively high levels of 14C were found in leaves and low levels in stems and flowers. After this treatment about half of the 14C-GA3 in leaves was metabolized into unknown compounds. 相似文献
6.
Straight-chain saturated fatty acids (C6-C11) and abscisic acid (ABA) accumulate in the leaves of Phaseolus vulgaris L. and Hordeum vulgare L. under water stress. ABA and certain of the fatty acids, particularly decanoic and undecanoic acid, can inhibit stomatal opening and cause stomatal closure in epidermal strips of Commelina communis L. depending on the incubating medium used. 10-4 M (±)-ABA inhibits opening in media containing either high or relatively low concentrations of KCl but causes closure only in the latter medium. The fatty acids (at 10-4 M) prevent opening in both media while significant closure of open stomata was caused only by undecanoic acid in both media and, additionally, by decanoic acid in the low-KCl medium. 10-4 M formic acid also caused stomatal closure and prevented opening to significant extents in the low-KCl medium (it was not tested in the high-KCl medium). The efficacy of undecanoic acid in causing 50% inhibition of opening is about three orders of magnitude lower than that of ABA. At a concentration of 10-3 M, nonanoic, decanoic and particularly undecanoic acid and all-trans-farnesol cause increased cell leakage in Beta vulgaris L. root tissue. Undecanoic acid (10-4 M) also causes some loss of guard cell integrity in C. communis within 1.5 h of treatment. ABA (10-4 M) reduces transpiration rates in barley and C. communis leaves when applied via the transpiration stream but decanoic and undecanoic acids did not have this effect. Transpiration was not affected when ABA or the fatty acids were applied to the leaf surfaces.Abbreviations ABA
abscisic acid
- RWC
relative water content
- SCFA
short-chain fatty acids
Deceased May 1977 相似文献
7.
The occurrence and toxicity of Amphidinium carterae Hulburt is hereby reported for the first time from the North Arabian Sea on the coast of Pakistan. The concentrations of 1.2 × 104 cells ml−1 were found in intertidal pools that were also inhabited by the brown macroalga Sargassum wightii. Both wild and cultured A. carterae cells were tested for ciguatera toxicity through exposure to brine shrimp nauplii (Artemia salina) and albino mice. Although the brine shrimp did not appear to be affected mortalities in mice ranged between 13 and 16% at doses of 7.2 × 104 and 2.5 × 105 cells ml−1, respectively. When mice were affected pharmacological effects such as muscle contraction in lower back area, increased respiration, immobility and paralysis in hind limbs were observed for 2 h. These effects appeared to be reversible and gradually disappeared within 24 h. 相似文献
8.
Susceptibility of Larvae of Galleria mellonella to Infection by Aspergillus fumigatus is Dependent upon Stage of Conidial Germination 总被引:1,自引:0,他引:1
The ability of conidia of the human pathogenic fungus Aspergillus fumigatus to kill larvae of the insect Galleria mellonella was investigated. Conidia at different stages of the germination process displayed variations in their virulence as measured
using the Galleria infection model. Non-germinating (‘resting’) conidia were avirulent except when an inoculation density of 1 × 107 conidia per insect was used. Conidia that had been induced to commence the germination process by pre-culturing in growth
medium for 3 h were capable of killing larvae at densities of 1 × 106 and 1 × 107 per insect. An inoculation density of 1 × 105 conidia per insect remained avirulent. Conidia in the outgrowth phase of germination (characterised as the formation of a
germ tube) were the most virulent and were capable of killing 100% of larvae after 5 or 24 h when 1 × 107 or 1 × 106 conidia, that had been allowed to germinate for 24 h, were used. Examination of the response of insect haemocytes to conidia
at different stages of the germination process established that haemocytes could engulf non-germinating conidia and those
in the early stages of the germination process but that conidia, which had reached the outgrowth stages of germination were
not phagocytosed. The results presented here indicate that haemocytes of G. mellonella are capable of phagocytosing A. fumigatus conidia less than 3.0 μm in diameter but that conidia greater than this are too large to be engulfed. The virulence of A. fumigatus in G. mellonella larvae can be ascertained within 60–90 h if infection densities of 1 × 106 or 1 × 107 activated conidia (pre-incubated for 2–3 h) per insect are employed. 相似文献
9.
D'Souza David R. Morgan Richard D. Parashar Vijay Capalash Neena Sharma Prince 《World journal of microbiology & biotechnology》2004,20(6):593-598
A thermophile, isolated from geothermal areas in the northern Himalayan region of India, was identified by partial 16S rDNA
sequence (GenBank accession # AF482430) analysis as Anoxybacillus flavithermus. The isolate produced BflI (REBASE # 4910), a Type II restriction endonuclease, which recognized the sequence 5′-CCNNNNN/NNGG-3′ and was the isoschizomer
of BsiYI. The enzyme was purified to homogeneity by passing through Cibacron Blue F3GA agarose, DEAE-cellulose, heparin-agarose
and MonoQ FPLC. The purified enzyme (MW 36 kDa) worked best at 60 °C in Promega's buffer C and preferentially required Co++(0.4 mM) as cofactor followed by Mg++(10 mM) and Mn++(1 mM). The enzyme showed high specific activity and worked in the presence of high concentrations of β-mercaptoethanol (200
mM), Triton-X-100 (25%), urea (30%), formamide (6%) and guanidine (40 mM) and showed no star activity in the presence of 40%
glycerol. In the absence of any stabilizing agent, BflI retained t
1/2 for at least 96 h at 37 °C, 6 h at 60 °C and 6 months at 4 °C. N-terminal sequencing showed that its first 10 amino acid
residues were DFHEDKTIAR.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Lipopolysaccharide of Escherichia coli, polyamines, and acetic acid stimulate cell proliferation in intestinal epithelial cells 总被引:1,自引:0,他引:1
Jaime Olaya Vadim Neopikhanov Andrés Uribe 《In vitro cellular & developmental biology. Animal》1999,35(1):43-48
Summary Our aim was to examine whether lipopolysaccharide of Escherichia coli, polyamines of dietetic and/or bacterial origin, and products of the bacterial metabolism influence cell proliferation in
epithelial cells from the colon and small intestine. Lipopolysaccharide of Escherichia coli 0111:B4 was incubated with cultures from human colonic mucosa. The mitoses were arrested with Vincristine and the total number
of metaphases per crypt was counted. In addition, lipopolysaccharide was incubated with a human colonic epithelial cell line
from adenocarcinoma (LS-123 cells) and with a nontransformed small intestinal cell line from germ-free rats (IEC-6 cells)
for 24 h. In the last 4 h, the cells were labeled with tritiated thymidine. The cells were incubated with putrescine, cadaverine,
and spermidine at 10−11–10−3
M and with acetic acid (10−5–10−1
M), acetaldehyde (10−10–10−4
M) and ammonium chloride (1–20 mM). Lipopolysaccharide of Escherichia coli increased the number of arrested metaphases in human colonic crypts and DNA synthesis in L-123 and IEC-6 cells (P<0.001). All polyamines increased DNA synthesis in the colonic and small intestinal cell lines, the effects being more marked
for putrescine (P<0.001). The higher concentrations of acetic acid increased DNA synthesis in both epithelial cell lines (P<0.001). Acetaldehyde slightly decreased DNA synthesis in LS-123 cells at cytotoxic concentrations. Ammonium chloride did
not significantly affect DNA synthesis. The final concentration of nonionized ammonia was less than 3%. It is concluded that
lipopolysaccharides of Escherichia coli and intraluminal factors derived from microorganisms increase cell proliferation in human colonic crypts and intestinal epithelial
cell lines. 相似文献
11.
E. S. Dias E. F. Araújo W. V. Guimarães R. M. C. Muchovej 《World journal of microbiology & biotechnology》1996,12(6):625-628
Experiments were performed with the mycorrhizal fungus Suillus granulatus to define the parameters for production and regeneration of protoplasts. Protoplasts were released at frequencies between 1 and 3×107/ml from mycelium 3 to 7 days old. The best osmotic stabilizer for protoplast release was MgSO4 (0.7 m). To optimize protoplast release and regeneration an enzyme (Novozym 234) concentration 1.7 mg/ml was chosen, with a digestion time of 1 to 2 h. Regenerated colonies formed mycorrhizae within 60 days after inoculation in Pinus caribaea var. hondurensis seedlings. 相似文献
12.
AxenicTrentepohlia odorata was cultured at three different NH4Cl levels (3.5 × 10–2, 3.5 × 10–3, 3.5 × 10–4 M) and three different light intensities (48, 76, 122 µmol m–2 s–1). Chloride had no effect on growth over this range of concentration. High light intensity and high NH4Cl concentration enhanced the specific growth rate. The carotenoid content increased under a combination of high light intensity and low N concentration. WhenD. bardawil was exposed to the same combination of growth conditions, there was an increase in its carotenoid content. The light saturation and the light inhibition constants (K
s andK
i, respectively) for growth, and the saturation constant (K
m) for NH4Cl were determined. TheK
s andK
i values were higher inT. odorata (66.7 and> 122 mol m–2 s–1, respectively) than inD. bardawil (5.1 and 14.7 µmol m–2 s–1, respectively). TheK
m value determined at 122 µmol m–2 s–1, however, was lower inT. odorata (0.048 µM) than inD. bardawil (0.062 µM).Author for correspondence 相似文献
13.
A milk–soymilk mixture was fermented using Lactobacillus paracasei subsp. paracasei NTU101 and Bifidobacterium longum BCRC11847 at different inoculum ratios (1:1, 1:2, 1:5, 2:1, and 5:1). When the inoculum ratio was 1:2, the cell numbers of both strains were balanced after 12 h of cultivation. The pH and titratable acidity were very similar at the various inoculum ratios of cultivation. The milk–soymilk mixture was supplemented with 5, 10, 15, and 20% Lycium chinense Miller juice and fermented with Lactobacillus paracasei subsp. paracasei NTU101 and B. longum BCRC11847. Sensory evaluation results showed that supplementation with 5% Lycium chinense Miller juice improved the acceptability of the fermented milk–soymilk. The fermented beverage was stored at 4°C for 14 days; variations in pH and titratable acidity were slight. The cell numbers of L. paracasei subsp. paracasei NTU101 and B. longum BCRC11847 in the fermented beverage were maintained at 1.2×109 CFU/ml and 6.3×108 CFU/ml, respectively, after 14 days of storage. 相似文献
14.
R. I. Samuels D. L. A. Coracini C. A. Martins dos Santos C. A. T. Gava 《Biological Control》2002,23(3):269
This study determined the pathogenicity and virulence of Beauveria bassiana and Metarhizium anisopliae to eggs of the chinch bug Blissus antillus (Hemiptera: Lygaeidae). Eggs were inoculated under laboratory conditions by immersion in concentrations of 1 × 104 and 5 × 106 conidia/ml. Inoculated eggs were kept under controlled conditions. Evaluations were carried out daily for 20 days. M. anisopliae isolates were highly virulent to eggs, even at 1 × 104 conidia/ml. All B. bassiana isolates tested were considered to be of low virulence or avirulent. The most virulent isolate tested was ESALQ 818 (M. anisopliae), which caused 96.7% infection, when eggs were immersed in suspensions of 1 × 104 conidia/ml. Conidial production on infected eggs was observed to be highest for M. anisopliae isolate CG144, with a mean value of 11.6 × 105 conidia/ml/egg. Infection of Blissus eggs oviposited on plant stems was greater when M. anisopliae isolate CG144 was formulated in mineral oil (63.5% mortality) than when formulated in Tween 80 (27.1% mortality). 相似文献
15.
An enzyme-linked immunoassay coupled with a tyrosinase modified enzyme electrode was used for rapid detection of Campylobacter jejuni. The immunomagnetic separation (IMS) method was investigated to achieve optimal isolation of C. jejuni cells. Eight types of beads with three different sizes and function groups were coated with anti-C. jejuni to isolate C. jejuni from the sample solution. Bead size and coating methods were found to be major factors that influenced the capture efficacy. Streptavidin-labeled beads (2.8 μm) provided the greatest capture ability. Three blocking reagents were tested to minimize non-specific binding. Bovine serum albumin (BSA) showed the best blocking capability. Two IMS formats were tested. Competitive immunoassay cut the detection time to 1.5 h, but the detection limit was relatively high (106 CFU/ml). This system was evaluated using C. jejuni pure culture and poultry samples inoculated with C. jejuni. This detection method for C. jejuni could be completed within 2.5 h and had a detection limit of 2.1×104 CFU/ml. No significant difference was found between pure culture samples and poultry samples (P>0.01). A linear relationship was found between C. jejuni cell numbers and the peak current ratio in a range of 102–107 CFU/ml (R2=0.94). 相似文献
16.
Real-time PCR assay for the simultaneous quantification of nitrifying and denitrifying bacteria in activated sludge 总被引:5,自引:0,他引:5
Geets J de Cooman M Wittebolle L Heylen K Vanparys B De Vos P Verstraete W Boon N 《Applied microbiology and biotechnology》2007,75(1):211-221
In order to improve wastewater treatment processes, a need exists for tools that rapidly give detailed insight into the community
structure of activated sludge, supplementary to chemical and physical data. In this study, the advantages of microarrays and
quantitative polymerase chin reaction (PCR) methods were combined into a real-time PCR assay that allows the simultaneous
quantification of phylogenetic and functional genes involved in nitrification and denitrification processes. Simultaneous
quantification was possible along a 5-log dynamic range and with high linear correlation (R
2 > 0.98). The specificity of the assay was confirmed by cloning and sequencing analyses of PCR amplicons obtained from activated
sludge. The real-time assay was validated on mixed liquid samples of different treatment plants, which varied in nitrogen
removal rate. The abundance of ammonia oxidizers was in the order of magnitude of 106 down to 104 ml−1, whereas nitrite oxidizers were less abundant (103–101 order of magnitude). The results were in correspondence with the nitrite oxidation rate in the sludge types. As for the nirS, nirK, and nosZ gene copy numbers, their abundance was generally in the order of magnitude of 108–105. When sludge samples were subjected to lab-scale perturbations, a decrease in nitrification rate was reflected within 18 h
in the copy numbers of nitrifier genes (decrease with 1 to 5 log units), whereas denitrification genes remained rather unaffected.
These results demonstrate that the method is a fast and accurate tool for the analysis of the (de)nitrifying community structure
and size in both natural and engineered environmental samples.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
17.
Biological control of crown rot of bananas with Pichia anomala strain K and Candida oleophila strain O 总被引:1,自引:0,他引:1
The antagonistic activity of two yeast strains (Pichia anomala (E.C. Hansen) Kurtzman, strain K and Candida oleophila Montrocher, strain O) against the parasitic complex responsible for banana crown rot was evaluated. The strains were applied at three different concentrations (106, 107, 108 cfu/ml) and their efficacy tested in vivo on three separate fungi (Colletotrichum musae (Berk. & Curt.) Arx, Fusarium moniliforme Sheldon, and Cephalosporium sp.) and on a parasitic complex formed by association of these three fungi. At the concentrations used C. musae appeared to be the most pathogenic. The complex showed intermediate aggressiveness between C. musae and both other fungi.Statistically significant antagonistic effects were observed on C. musae, F. moniliforme, and the fungal complex. The highest protection level (54.4%) was observed with strain O added at 108 cfu/ml on crowns previously inoculated with the fungal complex. The level was lower when the fungi were inoculated separately.Furthermore, the antagonistic effect was strongly reinforced when strain O at 108 cfu/ml was applied 24 h before fungal complex inoculation (59.9%), as compared to its application 15 min (24.3%) or 3 h (27.3%) after fungal complex inoculation. Bananas showed increased susceptibility to the fungal complex from March to June, and this influenced the level of protection by yeast, which decreased over the same period. A strict negative correlation (R2 = 0.83) was highlighted between susceptibility of banana to crown rot and protection provided by yeast. 相似文献
18.
Mustafa Çelik Fatma Ünal Deniz Yüzbaşıoğlu Serkan Yılmaz Hüseyin Aksoy Şengül Karaman 《Cytotechnology》2006,51(2):99-104
In this investigation, clastogenic effects of Thymus kotschyanus var. glabrescens Boiss. extract (TE) and anticlastogenic effects of this extract against Mitomycin C (MMC) induced chromosome damage have been evaluated in human peripheral blood lymphocytes in vitro. Two series of experiments were conducted. In the first, only 10−5, 10−4, 10−3 and 10−2 μl ml−1 concentrations of TE were used for 48 h to detect potential clastogenicity. In the second, MMC (0.38 μg ml−1) plus 10−5, 10−4, 10−3 and 10−2 μl ml−1 concentrations of TE were used for 48 h to determine anticlastogenic effects. TE did not increase sister chromatid exchanges (SCEs) (except 10−2 μl ml concentration) and chromosome aberrations (CAs) significantly compared with negative and solvent controls. However, it decreased the frequency of MMC induced chromosome aberrations. Decreasing was significant at 10−4, 10−3 and 10−2 μl ml−1 concentrations. On the other hand, TE significantly increased MMC-induced SCEs for all treatment groups compared with positive control. 相似文献
19.
In the first part of this study, four isolates of the fungus Beauveria bassiana (Bals.) Vuillemin (LPP1, LPP2, CG05 and CG24) and one isolate of Metarhizium anisopliae (Metsch.) Sorokin (CG46) were tested against adult foragers of Atta sexdens rubropilosa. Ants were allowed to walk on filter paper discs, inside Petri dishes, previously impregnated with 1 ml of a conidia suspension
(2 × 107 conidia ml−1), maintained at 80% RH and 26°C for 24 h and subsequently, transferred to sterile Petri dishes, maintained at 23°C, 80% RH,
24 h dark. The mean values of LT50 for LPP2, LPP1, CG46, CG24 and CG05 were 3.5, 3.7, 3.8, 4.2 and 4.4 days, respectively. Control insects for all tests in
this study showed less than 10% mortality. Experiments were carried out to test the toxicity of imidacloprid (IMI) to A. sexdens rubropilosa. Mortality was evaluated 10 days following a 24 h exposure to the insecticide. Percent mortality caused by 500, 200, 100
and 10 ppm IMI was 77.8, 56.7, 45.5 and 5.5 respectively. Insects treated with 10 ppm IMI were observed to have reduced locomotor
activity 24 h after exposure to the insecticide. The LC50 of IMI was 154.3 ppm. Subsequent tests were carried out to evaluate the combination of a sub-lethal dose of IMI (10 ppm)
and infection by CG24 (1 × 107 conidia ml−1). Mortality due to fungal infection alone was 43.3%. Mortality of insects treated with IMI followed by exposure to the fungus
was 64.3%. These results indicate that IMI significantly increases the susceptibility of ants to infection by B. bassiana CG24. 相似文献
20.
Feeding rate inhibition in crowded Daphnia pulex 总被引:2,自引:2,他引:0
Judith C. Helgen 《Hydrobiologia》1987,154(1):113-119
Feeding rates of Daphnia pulex fed a range of levels of the alga Chlamydomonas reinhardi of 15 °C are strongly density-dependent. At lower densities, Daphnia (30 1–1) fed at higher rates than crowded (270 1–1) Daphnia which manifest a relatively depressed saturation feeding response. At 30 individuals/liter, Daphnia consumed 8.5 – 15.7 × 104 cells d–1h–1 (on a volume basis, 12.1 – 22.2 × 106 m3), at 270 L–1 3.7 – 3.9 × 104 (5.2 – 5.5 = 106 m3 cells d–1h–1 when feeding on algae at 80 000 cells ml–1 (11.3 × 106 m3 ml–1). The feeding rate data best fit an Ivlev feeding function. An autoallelopath might be causing the repression. Water preconditioned with crowded Daphnia completely repressed feeding in uncrowded Daphnia after six hours. 相似文献