A simple method for determining the sensitivity of micro-organisms to serial dilutions of antibiotics

1. A simple method is described for determining the substrate preferences of Corophium volutator (Pallas) and Corophium arenarium Crawford. 2. If offered a choice of its own substrate with that of the other species each prefers its own. 3. Level of illumination and colour of substrate have little effect on choice. An animal's size and hence its age has little effect on its substrate preferences. 4. C. volutator prefers a substrate previously maintained under anaerobic conditions, C. arenarium vice versa. 5. Treatments which kill, inactivate, or remove micro-organisms render sands unattractive to Corophium. These include boiling, acid-cleaning, drying, and soaking in fixatives or distilled water. Attempts to make these sands attractive again failed. 6. Distilled water, and solutions of the non-electrolytes sucrose and glycerol at the same osmotic pressure as sea water, induce many bacteria to desorb from sand particles; smaller numbers are desorbed in the presence of solutions of electrolytes at the same ionic strength as sea water (NaCl, Na2SO4, KC1, MgSO4, MgCl2, CaCl2). Of all these, only distilled water and solutions of MgCl2 and CaCl2 reduce the attractive properties of sands. Hence the loss of bacteria from the surface of sand grains, though related to the ionic strength and composition of the medium, is not necessarily associated with a substrate becoming unattractive.

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A simple method for the detection of lipolytic activity of micro-organisms and some observations on the influence of the contact between cells and fatty substrates

Antonie van Leeuwenhoek ◽

10.1007/bf02545855 ◽

1957 ◽

Vol 23 (1) ◽

pp. 15-22 ◽

Cited By ~ 443

Author(s):

Gonzalo Sierra

Keyword(s):

Lipolytic Activity ◽

Simple Method ◽

Micro Organisms

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Screening of osmotolerant micro organisms in the dried salted fish sold in kanyakumari district, tamilnadu

Kongunadu Research Journal ◽

10.26524/krj.2020.7 ◽

2020 ◽

Vol 7 (1) ◽

pp. 39-49

Author(s):

Mary Kensa V ◽

Anju M

Keyword(s):

Moisture Content ◽

Pathogenic Bacteria ◽

Nutritive Value ◽

Fungal Species ◽

Human Pathogens ◽

Simple Method ◽

Salted Fish ◽

Fish Samples ◽

Micro Organisms ◽

The Tropics

Fish is one of the most important sources of animal protein available in the tropics and has been widely accepted as a good source of protein and other elements for the maintenance of healthy body. Salting and drying is an ancient and simple method to preserve fish and in India about 17% of the total catch is beingused for salting and drying. The present investigation was aimed to analyse the presence of osmotolerant microbes in the dry fishes. The commercially important marine edible salted dry fishes were collected from the study area Pallam. Four common edible dry fishes like (Nethili, Sardines, Ribbon fish and Prawn) wereselected for the screening of microbial population. The highest TFC value was reported in Sardine and Ribbon fish (5103) than the other fishes like Netthili and Prawn (4103 and 2103). The moisture content was higher (45%) in Prawn followed by Ribbon fish (40%), Sardines (29%), Netthili (26%). In this study,Prawn had high moisture content (45%) and high microbial load (5.3104 cfu/g). Total five fungal species were isolated from the selected dried fishes. The result of isolation of human pathogens such as Salmonella and Vibrio identified from the selected dry fish samples. The nutritive value of raw fish in found to be good.The sensory characteristics such as colour, odor, texture, insect infestation showed that the Sardine and Prawn was good in quality, while the netthili had decreased the quality. The study showed that salted and sundried fishes sold in study area are contaminated with pathogenic bacteria and fungal agents. Spoilage ofdried fish products was found and this might be due to unhygienic handling of the fisher folks, improper processing and unhygienic vendors and vending areas.

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Review of the Radiation Damage Problem of Organic Specimens in Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072824 ◽

1973 ◽

Vol 31 ◽

pp. 476-477

Author(s):

L. Reimer

Keyword(s):

Electron Microscopy ◽

Radiation Damage ◽

Irradiation Time ◽

Dose Effect ◽

Primary Process ◽

Thin Specimen ◽

Secondary Damage ◽

Small Doses ◽

Micro Organisms ◽

Damage Processes

Most information about a specimen is obtained by elastic scattering of electrons, but one cannot avoid inelastic scattering and therefore radiation damage by ionisation as a primary process of damage. This damage is a dose effect, being proportional to the product of lectron current density j and the irradiation time t in Coul.cm−2 as long as there is a negligible heating of the specimen.Therefore one has to determine the dose needed to produce secondary damage processes, which can be measured quantitatively by a chemical or physical effect in the thin specimen. The survival of micro-organisms or the decrease of photoconductivity and cathodoluminescence are such effects needing very small doses (see table).

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A simple way for producing holographic filters suitable for image improvement

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108271 ◽

1978 ◽

Vol 36 (1) ◽

pp. 226-227

Author(s):

K.-H. Herrmann ◽

E. Reuber ◽

P. Schiske

Keyword(s):

Transfer Functions ◽

Diffraction Order ◽

Lateral Position ◽

Simple Method ◽

Spatial Frequencies ◽

Resolution Electron ◽

Wiener Filters ◽

Image Improvement ◽

Optical Reconstruction ◽

Set Up

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

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Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099192 ◽

1981 ◽

Vol 39 ◽

pp. 550-551

Author(s):

Dean A. Handley ◽

Jack T. Alexander ◽

Shu Chien

Keyword(s):

Cell Growth ◽

Cell Cultures ◽

Molecular Interactions ◽

Convenient Method ◽

Petri Dish ◽

Simple Method ◽

Thin Section Microscopy ◽

Thin Sectioning ◽

Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

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Functional amyloid: widespread in Nature, diverse in purpose

Essays in Biochemistry ◽

10.1042/bse0560207 ◽

2014 ◽

Vol 56 ◽

pp. 207-219 ◽

Cited By ~ 77

Author(s):

Chi L.L. Pham ◽

Ann H. Kwan ◽

Margaret Sunde

Keyword(s):

Spider Silk ◽

Epigenetic Inheritance ◽

Fibrillar Structure ◽

Cytoplasmic Polyadenylation ◽

Functional Amyloid ◽

Interacting Protein ◽

Diverse Range ◽

Element Binding Protein ◽

Functional Amyloids ◽

Micro Organisms

Amyloids are insoluble fibrillar protein deposits with an underlying cross-β structure initially discovered in the context of human diseases. However, it is now clear that the same fibrillar structure is used by many organisms, from bacteria to humans, in order to achieve a diverse range of biological functions. These functions include structure and protection (e.g. curli and chorion proteins, and insect and spider silk proteins), aiding interface transitions and cell–cell recognition (e.g. chaplins, rodlins and hydrophobins), protein control and storage (e.g. Microcin E492, modulins and PMEL), and epigenetic inheritance and memory [e.g. Sup35, Ure2p, HET-s and CPEB (cytoplasmic polyadenylation element-binding protein)]. As more examples of functional amyloid come to light, the list of roles associated with functional amyloids has continued to expand. More recently, amyloids have also been implicated in signal transduction [e.g. RIP1/RIP3 (receptor-interacting protein)] and perhaps in host defence [e.g. aDrs (anionic dermaseptin) peptide]. The present chapter discusses in detail functional amyloids that are used in Nature by micro-organisms, non-mammalian animals and mammals, including the biological roles that they play, their molecular composition and how they assemble, as well as the coping strategies that organisms have evolved to avoid the potential toxicity of functional amyloid.

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