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1.
Kitty J. A. van Spreekens 《Antonie van Leeuwenhoek》1977,43(3-4):283-303
The classification of some important groups of bacteria involved in fish and shrimp spoilage was studied.
Trimethylamine is produced byPseudomonas putrefaciens, a “non-defined” group resemblingPs. putrefaciens, Photobacterium spp. and someMoraxella-like bacteria.
Hypoxanthine is produced by the same groups of bacteria except the last named and also by the “typical shrimp spoilers” (presumptiveAlteromonas).
Strong off-odours are produced on fresh fish byPs. putrefaciens, dextroseoxidativePseudomonas spp. (Groups I and 11 according to Shewan, Hobbs and Hodgkiss, 1960), the above mentioned “non-defined” group and by only
some of the “typical shrimp spoilers”, whereasMoraxella-like bacteria andPhotobacterium spp. failed to produce strong odours.
Strong off-odours are produced on boiled shrimp by the “typical shrimp spoilers” (presumptiveAltermonas),Ps. putrefaciens, the dextrose-oxidativePseudomonas spp. and the “non-defined” group;Moraxella-like bacteria produced less offensive odours or none, nor didPhotobacterium. 相似文献
2.
We propose a simple experiment to study delocalization and extinction in inhomogeneous biological systems. The nonlinear
steady state for, say, a bacteria colony living on and near a patch of nutrient or favorable illumination (“oasis”) in the
presence of a drift term (“wind”) is computed. The bacteria, described by a simple generalization of the Fisher equation,
diffuse, divide A→A + A, die A→ 0, and annihilate A + A→ 0. At high wind velocities all bacteria are blown into an unfavorable region (“desert”), and the colony dies out. At low
velocity a steady state concentration survives near the oasis. In between these two regimes there is a critical velocity at
which bacteria first survive. If the “desert” supports a small nonzero population, this extinction transition is replaced
by a delocalization transition with increasing velocity. Predictions for the behavior as a function of wind velocity are made
for one and two dimensions.
Received: 3 August 1998 / Revised version: 17 July 1999 / Published online: 4 July 2000 相似文献
3.
C. Brahmi A. Meibom D. C. Smith J. Stolarski S. Auzoux-Bordenave J. Nouet D. Doumenc C. Djediat I. Domart-Coulon 《Coral reefs (Online)》2010,29(1):175-189
The biomineralization process and skeletal growth dynamics of azooxanthellate corals are poorly known. Here, the growth rate
of the shallow-water dendrophyllid scleractinian coral Balanophyllia regia was evaluated with calcein-labeling experiments that showed higher lateral than vertical extension. The structure, mineralogy
and trace element composition of the skeleton were characterized at high spatial resolution. The epitheca and basal floor
had the same ultrastructural organization as septa, indicating a common biological control over their formation. In all of
these aragonitic skeletal structures, two main ultrastructural components were present: “centers of calcification” (COC) also
called rapid accretion deposits (RAD) and “fibers” (thickening deposits, TD). Heterogeneity in the trace element composition,
i.e., the Sr/Ca and Mg/Ca ratios, was correlated with the ultrastructural organization: magnesium was enriched by a factor
three in the rapid accretion deposits compared with the thickening deposits. At the interface with the skeleton, the skeletogenic
tissue (calicoblastic epithelium) was characterized by heterogeneity of cell types, with chromophile cells distributed in
clusters regularly spaced between calicoblasts. Cytoplasmic extensions at the apical surface of the calicoblastic epithelium
created a three-dimensional organization that could be related to the skeletal surface microarchitecture. Combined measurements
of growth rate and skeletal ultrastructural increments suggest that azooxanthellate shallow-water corals produce well-defined
daily growth steps. 相似文献
4.
A novel technique (“bioshrouding”) for safeguarding highly reactive sulfidic mineral tailings deposits is proposed. In this,
freshly milled wastes are colonised with ferric iron-reducing heterotrophic acidophilic bacteria that form biofilms on reactive
mineral surfaces, thereby preventing or minimising colonisation by iron sulfide-oxidising chemolithotrophs such as Acidithiobacillus ferrooxidans and Leptospirillum spp. Data from initial experiments showed that dissolution of pyrite could be reduced by between 57 and 75% by “bioshrouding”
the mineral with three different species of heterotrophic acidophiles (Acidiphilium, Acidocella and Acidobacterium spp.), under conditions that were conducive to microbial oxidative dissolution of the iron sulfide. 相似文献
5.
PPP protein phosphatases are an important enzyme family involved in a variety of aspects of cellular signalling and metabolism.
PPPs are ubiquitous in eukaryotes, and are also present in many bacteria. Canonical eukaryotic PPP phosphotases are represented
by five major subfamilies (PP1, PP2A, calcineurin, PP5 and PPEF/PP7). We previously reported that three “bacterial-like” PPP
groups span the prokaryote–eukaryote boundary, including “Shewanella-like” phosphatases (Shelphs), which are in the focus of this study. Here we predict possible biological functions and functional
partners of Shelphs by examining composition of bacterial operons and expression data for eukaryotes available in public databases.
In Arabidopsis thaliana, the predicted possible roles include light-dependent regulation of chloroplast functions, signalling between the nucleus
and the chloroplast, and defence responses. In Plasmodium falciparum, Shelphs are predicted to be associated with host cell invasion. One isoform has been located in the apical complex, essential
for the interaction with the host cell. This makes P. falciparum Shelphs obvious potential candidates for therapeutic targets. Shelphs are also present in bacteria that constitute a considerable
proportion of symbiotic microflora in humans. The predicted involvement of bacterial Shelphs in sensing and import of nutrients
and extrusion of toxins may be relevant to the links between physiology of humans and our symbionts. Thus, despite the absence
of Shelphs in animals, including humans, they may have a direct relationship to human health. Some predicted biological processes
and potential functional partners of Shelphs are common between different bacterial and/or eukaryotic lineages, suggesting
evolutionary conservation of some Shelph regulatory modules. 相似文献
6.
Microrheological properties (aggregation and deformability) of erythrocytes separated by centrifugation at 30000×g density gradient into “young” and “old” (the upper and lower fractions, respectively) were studied. The erythrocytes were
taken from physically active persons (PAP) and from those with elevated arterial pressure (EAP). A significant difference
in microrheological properties of the “young” and “old” erythrocytes was found. The aggregation degree of “old” cells was
nearly twice that of “young” cells. The deformability of the erythrocyte subpopulations was significantly different, though
the difference was not so pronounced as in the case of aggregation. The aggregation of “young” and “old” erythrocytes in the
PAP group was the least (28% lower than in the control). Note, that “old” erythrocytes in the PAP group had better microrheological
properties than in the other groups. All erythrocyte populations in the EAP group were characterized by higher aggregation,
decreased deformability, and decreased capacity for oxygen transport. 相似文献
7.
The present study has been carried out in an organic winery established in 2003 in the Denomination of Origin “Sierras de
Málaga” (Southern Spain) region during the 2007 vintage. The aim of this work was to ascertain the yeast microflora present
in the winery and during the vinifications and to obtain a collection of autochthonous S. cerevisiae strains from this area. Yeast populations from three vats containing fermenting musts from different grape varieties were
analysed. Two of them were inoculated with a natural “pied de cuve” while the third one was sown with a rehydrated commercial
yeast strain. A total of 382 yeasts were isolated and identified, initially by restriction analysis of ribosomal DNA and further
by sequencing of this region. Non-Saccharomyces yeasts were found in all three musts but they practically disappeared as the fermentations progressed. Analysis of mitochondrial
DNA RFLP revealed 13 different restriction patterns of Saccharomyces cerevisiae strains, five of them similar to those of commercial strains used in the winery. Commercial strains were found even in vats
inoculated with a “pied de cuve” generated by spontaneous fermentation of a must sample. The analysis of samples recovered
from different winery surfaces and equipments demonstrated that non-Saccharomyces and both commercial and autochthonous Saccharomyces strains were part of the resident microflora in the winery. Biodiversity of autochthonous S. cerevisiae in fermentation vats was low but two of them were able to compete with the commercial ones and they were isolated even at
the end of the fermentation. 相似文献
8.
Ganitskaya Yu. V. Dinh The Dung Coi Tran Huu Khasanov B. F. Feoktistova N. Yu. Surov A. V. 《Biology Bulletin》2022,49(1):29-35
Biology Bulletin - In dogs of native breeds (“Hmong,” “Phu Quoc,” and “Zang Soi”), the features of behavior pre-adapted to interaction with humans and formed in... 相似文献
9.
Colicins are toxic exoproteins produced by bacteria of colicinogenic strains ofEscherichia coli and some related species ofEnterobacteriaceae, during the growth of their cultures. They inhibit sensitive bacteria of the same family. About 35%E. coli strains appearing in human intestinal tract are colicinogenic. Synthesis of colicins is coded by genes located on Col plasmids.
Until now more than 34 types of colicins have been described, 21 of them in greater detail,viz. colicins A, B, D, E1–E9, Ia, Ib, JS, K, M, N, U, 5, 10. In general, their interaction with sensitive bacteria includes three steps: (1) binding of the colicin molecule to a specific receptor in the bacterial outer membrane; (2) its translocation through the cell envelope; and (3) its lethal interaction with the specific molecular target in the cell. The classification of colicins is based on differences
in the molecular events of these three steps.
The original version of this review was published in Czech in the journal “Biologické listy”,62, 107–130 (1997). 相似文献
10.
Maria Serena Britti Marianna Roselli Alberto Finamore Nicolò Merendino Elena Mengheri 《Biologia》2006,61(6):735-740
The gut associated lymphoid tissue (GALT) should protect intestinal mucosa against pathogens, but also avoid hypersensitivity
reactions to food proteins, normal bacterial flora and other environmental macromolecules. The interaction between epithelial
cells and microflora is fundamental to establish gut mucosal barrier and GALT development. The normal colonization of intestine
by commensal bacteria is thus crucial for a correct development of mucosal immune system. Probiotic bacteria are normal inhabitants
of microflora and may confer health benefits to the host. The modification of the intestinal microflora towards a healthier
probiotics enriched microflora may generate beneficial mucosal immunomodulatory effects and may represent a new strategy to
cure intestinal and allergic diseases. The health benefits may be specific for different probiotic strains. Ongoing research
is providing new insights into the probiotic beneficial effects and related mechanisms. This review represents an update of
immunomodulatory activity of different probiotics and of the more accredited mechanisms underlying such activities.
Presented at the Second Probiotic Conference, Košice, 15–19 September 2004, Slovakia. 相似文献
11.
Ken Shortman D. Scott Linthicum Frank L. Battye Irving Goldschneider Andre Liabeuf Pierre Golstein Edward A. Clark Phil Lake 《Cell biochemistry and biophysics》1979,1(3):255-270
A number of analytical techniques for distinguishing and separating the “high θ” and “low θ” subpopulations of mouse thymocytes
have been compared. A differential cytotoxic assay was compared to a quantitative immunofluorescent assay on individual cells
using flow cytofluorometry and cell sorting. Conventional anti-Thy-1 antisera were compared with a monoclonal IgM anti-Thy-1.
The monoclonal reagent greatly improved both types of assay, eliminated a number of artifacts and allowed either procedure
to be used to give a clear distinction, based on Thy-1 level, between the two subpopulations. The distribution of Thy-1 on
thymocytes is bimodal, rather than continuous. These separate “high θ” and “low θ” categories each includes a population of
dividing cells. 相似文献
12.
We recently classified 23 bacteria into two types based on their complete genomes; “S-type” as represented by Staphylococcus aureus and “E-type” as represented by Escherichia coli. Classification was characterized by concentrations of Arg, Ala or Lys in the amino acid composition calculated from the
complete genome. Based on these previous classifications, not only prokaryotic but also eukaryotic genome structures were
investigated by amino acid compositions and nucleotide contents. Organisms consisting of 112 bacteria, 15 archaea and 18 eukaryotes
were classified into two major groups by cluster analysis using GC contents at the three codon positions calculated from complete
genomes. The 145 organisms were classified into “AT-type” and “GC-type” represented by high A or T (low G or C) and high G
or C (low A or T) contents, respectively, at every third codon position. Reciprocal changes between G or C and A or T contents
at the third codon position occurred almost synchronously in every codon among the organisms. Correlations between amino acid
concentrations (Ala, Ile and Lys) and the nucleotide contents at the codon position were obtained in both “AT-type” and “GC-type”
organisms, but with different regression coefficients. In certain correlations of amino acid concentrations with GC contents,
eukaryotes, archaea and bacteria showed different behaviors; thus these kingdoms evolved differently. All organisms are basically
classifiable into two groups having characteristic codon patterns; organisms with low GC and high AT contents at the third
codon position and their derivatives, and organisms with an inverse relationship. 相似文献
13.
Granado J Thürig B Kieffer E Petrini L Fliessbach A Tamm L Weibel FP Wyss GS 《Microbial ecology》2008,56(4):720-732
The effects of organic and integrated production systems on the culturable fungal microflora of stored apple fruits from five
matched pairs of certified organic and integrated ‘Golden Delicious’ farms were studied at five representative production
sites in Switzerland. Isolated fungi were identified morphologically. Colonization frequency (percentage of apples colonized),
abundance (colony numbers), and diversity (taxon richness) were assessed for each orchard. The standard quality of the stored
fruits was comparable for both organic and integrated apples and complied with national food hygiene standards. Yeasts (six
taxa) and the yeast-like fungus Aureobasidium pullulans were the dominant epiphytes, filamentous fungi (21 taxa) the dominant endophytes. The most common fungi occurred at all sites
and belonged to the “white” and “pink” yeasts, yeast-like A. pullulans, filamentous fungi Cladosporium spp., Alternaria spp., and sterile filamentous fungi. Canonical correspondence analysis of the total fungal community revealed a clear differentiation
among production systems and sites. Compared to integrated apples, organic apples had significantly higher frequencies of
filamentous fungi, abundance of total fungi, and taxon diversity. The effects of the production system on the fungal microflora
are most likely due to the different plant protection strategies. The incidence of potential mycotoxin producers such as Penicillium and Alternaria species was not different between production systems. We suggest that higher fungal diversity may generally be associated
with organic production and may increase the level of beneficial and antagonistically acting species known for their potential
to suppress apple pathogens, which may be an advantage to organic apples, e.g., in respect to natural disease control. 相似文献
14.
Hitoshi Murata 《Mycoscience》1999,40(1):81-85
A brown blotch bacterium,Pseudomonas tolaasii strain PT814, expresses a high degree of cross-protection against generalized stress imposed by physical/chemical treatment,
H2O2, UV, high temperature, ethanol and NaCl during the interaction withPleurotus ostreatus. Stress resistance was also noted in the bacterium in vitro under limited carbon and nitrogen sources. In addition, changes
in cell morphology from a “metabolically active” rod to an “energy-saving” spherical shape were detected during starvation
and the interaction. All the changes under stress were reversible. A homologue ofrpoS (σ
S), a regulator that controls such physiological status during starvation in other bacteria, was identified inP. tolaasii strain PT814. Data suggest that the bacterium is able to withstand a complex stress environment for its survival through
changes in its metabolic pattern. 相似文献
15.
Natasa Mitik-Dineva James Wang Vi Khanh Truong Paul Stoddart Francois Malherbe Russell J. Crawford Elena P. Ivanova 《Current microbiology》2009,58(3):268-273
Attachment tendencies of Escherichia coli K12, Pseudomonas aeruginosa ATCC 9027, and Staphylococcus aureus CIP 68.5 onto glass surfaces of different degrees of nanometer-scale roughness have been studied. Contact-angle and surface-charge
measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM)
were employed to characterize substrata and bacterial surfaces. Modification of the glass surface resulted in nanometer-scale
changes in the surface topography, whereas the physicochemical characteristics of the surfaces remained almost constant. AFM
analysis indicated that the overall surface roughness parameters were reduced by 60–70%. SEM, CLSM, and AFM analysis clearly
demonstrates that although E. coli, P. aeruginosa and S. aureus present significantly different patterns of attachment, all of the species exhibited a greater propensity for adhesion to
the “nano-smooth” surface. The bacteria responded to the surface modification with a remarkable change in cellular metabolic
activity, as shown by the characteristic cell morphologies, production of extracellular polymeric substances, and an increase
in the number of bacterial cells undergoing attachment. 相似文献
16.
The surface charge of bacterial cells plays an important role in their interfacial physiology and adhesion to substrata mediated
by the electrostatic double-layer interaction. The surface charge or potential of biological cells is generally calculated
from the experimentally measurable electrophoretic velocity of these cells migrating in an external electric field, applying
the well-known Smoluchowski equation which is valid for “hard” particles with a sharp interface. However, bacterial cells
possessing a structured outer membrane of a finite thickness (dependent on the ionic strength and pH of the surrounding liquid
medium) are expected to obey Ohshima's electrophoretic mobility equation derived recently for ‘soft” particles. The electrophoretic
mobility ofThiobacillus ferrooxidans was measured here by the fully automated technique of electrophoretic light scattering, based on the proportionality between
the mobility and the Doppler shift in the frequency of light scattered by electrophoresing cells. Agreement was obtained between
the experimentally determined electrophoretic mobility expressed as a function of low ionic strength (60–6000 μmol/L) at different
pH values and the best-fit theoretical predictions of the “soft” particle electrophoresis theory, which is better than in
the case of applying the Smoluchowski formula. The best-fit surface-charge and softness parameters predict a rather rigid
and low-charge outer membrane of the bacterium examined, as compared to the parameters obtained for other bacteria in media
of high ionic strength. 相似文献
17.
Frans B. M. de Waal Jan A. R. A. M. van Hooff Willem J. Netto 《Primates; journal of primatology》1976,17(3):257-290
The primate literature provides many indications not only that the nature of dyadic interactions is to a large extent determined
by the relations of the interacting animals with others and between these others, but also of the existence of polyadic interactions
in which more than two individuals are simultaneously involved.
The objectives of the present study are to obtain a quantitative categorization of the agonistic interaction types of captive
Java-monkeys and an analysis of their dynamics.
After having described the agonistic behaviour patterns of Java-monkeys we shall discuss the categorization of agonistic interaction
types (depending on the number of involvees: “dyads”, “triads” and “polyads”), the way in which these types can be further
differentiated on the basis of the nature and the direction of the behaviours shown (e.g., different types of alliances), and the existence of so-called “sub-directed” behaviours (i.e., non-agonistic behaviours which are shown towards a dominant third animal more or less simultaneously with aggressive behaviour
directed towards an opponent).
The analysis indicates that agonistic behaviour is different both in its form and its regulation in interactions of different
complexity.
This research was supported in part by a government grant (i.e.: Beleidsruimte project: 16-21-06, “Brain and Behaviour”) to
the first author.
The investigation was supported by a grant from the Beleidsruimtemiddelen Hersenen en Gedrag to the first author. 相似文献
18.
Several aerobic metabolic pathways for the degradation of benzene, toluene, ethylbenzene and xylene (BTEX), which are provided
by two enzymic systems (dioxygenases and monooxygenases), have been identified. The monooxygenase attacks methyl or ethyl
substituents of the aromatic ring, which are subsequently transformed by several oxidations to corresponding substituted pyrocatechols
or phenylglyoxal, respectively. Alternatively, one oxygen atom may be first incorporated into aromatic ring while the second
atom of the oxygen molecule is used for oxidation of either aromatic ring or a methyl group to corresponding pyrocatechols
or protocatechuic acid, respectively. The dioxygenase attacks aromatic ring with the formation of 2-hydroxy-substituted compounds.
Intermediates of the “upper” pathway are then mineralized by eitherortho-ormeta-ring cleavage (“lower” pathway). BTEX are relatively water-soluble and there-fore they are often mineralized by indigenous
microflora. Therefore, natural attenuation may be considered as a suitable way for the clean-up of BTEX contaminants from
gasoline-contaminated soil and groundwater. 相似文献
19.
Tahereh Makiabadi Audrey Bouvrée Victor Le Nader Hélène Terrisse Guy Louarn 《Plasmonics (Norwell, Mass.)》2010,5(1):21-29
Generally, the immobilization of two-dimensional nanoparticles in immersion procedures is time-consuming (over 24 h). In this
paper, we report a very effective and simple method to fabricate two-dimensional gold nanoparticle patterns over large areas
with high regularity for surface-enhanced Raman scattering (SERS). We achieved a highly sensitive SERS colloid surface by
optimizing temperature and immersion time. The surfaces were characterized by X-ray photoelectron spectroscopy, UV–Vis, atomic
force microscopy, and scanning electron microscopy. The SERS activity of surfaces was compared by using two techniques: “dip”
and “dip and dry” in an aqueous solution of 10−6 M crystal violet. The influence of the morphology of the surface was investigated with both the dip and dip and dry techniques. 相似文献
20.
Yuzuru Hamada 《Primates; journal of primatology》1984,25(4):485-506
A method based on the Fourier analysis is proposed, which describes and analyzes the contour morphology of carpal bones by
separating morphology into factors of shape and size. Here, “size” refers to the average diameter of the contour. The “shape”
is expressed byshape factors which are derived from the Fourier series and the “shape” of a monkey is expressed by ashape index which is calculated fromshape factors. The age change in the morphology of the lunate and capitate ofMacaca fuscata fuscata was analyzed by this method. The development of “shape” approximately completes by 3 years of age, whereas increase in “size”
begins its spurt at that age as do body weight and anterior trunk length. By applying this method to other macaque species,
it was found thatM. mulatta, M. f. yakui andM. cyclopis exhibit similar patterns of growth and development of carpal bones to those ofM. f. fuscata. Patterns found inM. fascicularis differ in that its bones develop faster than in the other macaques with respect to the “shape,” but remain small with respect
to the “size.” 相似文献