scholarly journals Unusual characteristics of the receptor for the N sex factor-specific filamentous phage IKe

1975 ◽  
Vol 25 (3) ◽  
pp. 275-284 ◽  
Author(s):  
Sheena Dennison ◽  
S. Baumberg
Keyword(s):  
High Speed ◽  
Liquid Culture ◽  
Direct Evidence ◽  
Filamentous Phage ◽  
Limited Extent ◽  
N Transfer ◽  
Incompatibility Group ◽  
Transfer Frequency ◽  
Low Ionic Strength ◽  
Strength Medium

SUMMARYPlasmid-mediated sensitivity to filamentous phage IKe is shown to be a property exclusive to plasmids of the N incompatibility group. As with other sex factor-specific phages, IKe sensitivity results from the provision of a plasmid-encoded receptor. However, direct evidence for IKe adsorption to a sex pilus-like structure is so far lacking.Mutations in an N plasmid were obtained which affected IKe infect-ability and N transfer frequency simultaneously, though to different extents. IKe receptors could be removed to a limited extent by high speed blending, but only under more extreme conditions (higher speed and in low ionic strength medium) than F pili. As with F-specific filamentous phages, IKe adsorption was partially blocked by Zn2+.We tentatively suggest that the results accord with the IKe receptor being a sex pilus rather different from F and I pili (possibly in being much shorter in liquid culture), but other interpretations of these data are possible.

COPPER ALLOY No. C94300

Alloy Digest ◽  
1984 ◽  
Vol 33 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Corrosion Resistance ◽  
Copper Alloy ◽  
High Speed ◽  
Heat Treating ◽  
Lead Alloy ◽  
Good Resistance ◽  
Tin Bronze ◽  
Strength Medium

Abstract Copper Alloy No. C94300 is a cast copper-tin-lead alloy (bronze). It is characterized by low hardness and strength, medium ductility, excellent machinability and good resistance to corrosion. Commercial names formerly used (but not recommended) are (1) Ingot No. 322, (2) Soft Bronze, (3) High-Leaded Tin Bronze and (4) 70-5-25. This alloy is recommended highly for high-speed bearings at light loads. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-470. Producer or source: Copper alloy foundries.

EFFECT OF HUMIC AND FULVIC ACIDS ON MICROBIAL GROWTH

2021 ◽  
Author(s):  
Milanka Radulovic ◽  
◽  
Svetlana Mitrovski
Keyword(s):  
Humic Acid ◽  
Humic Substances ◽  
Minimal Medium ◽  
Microbial Growth ◽  
Growth Curves ◽  
Fulvic Acids ◽  
Humic And Fulvic Acids ◽  
Staphyloccocus Aureus ◽  
Low Ionic Strength ◽  
Strength Medium

Peat is a natural substrate for growth of microorganisms because it is rich in compounds that microorganisms can use as sources of carbon, nitrogen and growth factors. Peat originating from Vlasina lake in Eastern Serbia is especially rich in organic matter. The content of humic substances (humic acid, fulvic acid and humine) is almost twice that found in other peat-rich regions of similar origin and geochemical age. Humic and fluvic acids are known to promote microbial growth. In this work, humic and fulvic acids were first extracted from Vlasina lake peat and then added to minimal medium (synthetic, low ionic strength medium). The humic substances were added separately and combined in a 1:1 ratio by mass to study their individual and combined effect on microbial growth of Escherichia coli ATCC 25922 (Gr–), Staphyloccocus aureus (Gr+) i Aureobasidium pullulans, strain CH-1. The microbial growth was measured microspectrophotometrically over a 24-hour period and growth curves were obtained for a range of acid concentrations between 25 µg cm-3 and 100 µg cm-3. It was found that both humic and fulvic acids promote the growth of all three microorganisms by up to a maximum of 40%-80% the extent of which varied with the concentration of the acid and the identity of the microorganism. In general, humic acid was found to result in higher microbial growth (at highest concentrations, up to ~80% for all three microbial species).

Increased Sensitivity of Tests for the Detection of Blood Group Antigens in Stains Using a Low Ionic Strength Medium

1978 ◽  
Vol 18 (1) ◽  
pp. 16-23 ◽  
Author(s):  
M. J. McDowall ◽  
P. J. Lincoln ◽  
B. E. Dodd
Keyword(s):  
Ionic Strength ◽  
Blood Group ◽  
Red Cells ◽  
Blood Group Antigens ◽  
Additional Advantage ◽  
Suspension Medium ◽  
Increased Sensitivity ◽  
Low Ionic Strength ◽  
Strength Medium

The incorporation of a low ionic strength solution (LISS) in the micro-elution technique used for the detection of blood group antigens in stains markedly improves the test's sensitivity. This is because LISS increases the amount of antibody taken up by the antigen in the stain which results in a greater yield of antibody recovered from the slain by elution. LISS also enhances the activity of the eluted antibody if it is introduced as a suspension medium for the red cells used to detect the antibody. The introduction of suitably diluted AB serum as diluent when testing the eluates is an additional advantage. The improvement in the sensitivity of the micro-elution technique is great enough in some instances to allow the detection of an antigen in a stain which is undetectable in the absence of LISS. Moreover some doubtful positive reactions are enhanced sufficiently for the presence of an antigen to be definitely established.

scholarly journals The human complement system: assembly of the classical pathway C3 convertase

1980 ◽  
Vol 189 (1) ◽  
pp. 173-181 ◽  
Author(s):  
M A Kerr
Keyword(s):  
Direct Evidence ◽  
Gel Filtration ◽  
Fluid Phase ◽  
Classical Pathway ◽  
Human Complement ◽  
Stabilizing Effect ◽  
Excess Substrate ◽  
High Concentrations ◽  
Low Ionic Strength

The assembly of the classical pathway C3 convertase in the fluid phase has been studied. The enzyme is assembled from C2 and C4 on cleavage of these proteins by C1s. Once assembled, the enzyme activity decays rapidly. Kinetic evidence has been obtained that this decay is even more rapid than previously suggested (kdecay is 2.0 min-1 at 37 degrees C). As a result, optimal C3 convertase activity is only observed with high C1s levels, which result in rapid rates of cleavage of C2 and increased rates of formation of the C3 convertase. Using high concentrations of C1s at lower temperatures (22 degrees C) in the presence of excess substrate we have demonstrated kinetically that the enzyme comprises an equimolar complex of C4b and cleaved C2. We have obtained direct evidence from gel-filtration experiments for the role of C2a as the catalytic subunit of the enzyme. C2b appears to mediate the interaction between C4 (or C4b) and C2 at pH 8.5 and at low ionic strength where the interactions can easily be detected. It may therefore be important in the assembly of the enzyme, though it is not involved in the catalytic activity. The decay of the C3 convertase reflects the release of C2a from the C4b x (C2b) x C2a complex, and the stabilizing effect of iodine on the C3 convertase is therefore apparently one of stabilizing the C4b-C2z interaction, which is otherwise weak. C1s is not a part of the C3 convertase enzyme.

scholarly journals Direct measurement of TRPV4 and PIEZO1 activity reveals multiple mechanotransduction pathways in chondrocytes

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
M Rocio Servin-Vences ◽  
Mirko Moroni ◽  
Gary R Lewin ◽  
Kate Poole
Keyword(s):  
High Speed ◽  
Direct Evidence ◽  
Mechanical Stimuli ◽  
Functional Importance ◽  
Mechanical Loads ◽  
Mechanoelectrical Transduction ◽  
Cartilage Homeostasis ◽  
Cell Substrate ◽  
Pillar Arrays ◽  
Current Activation

The joints of mammals are lined with cartilage, comprised of individual chondrocytes embedded in a specialized extracellular matrix. Chondrocytes experience a complex mechanical environment and respond to changing mechanical loads in order to maintain cartilage homeostasis. It has been proposed that mechanically gated ion channels are of functional importance in chondrocyte mechanotransduction; however, direct evidence of mechanical current activation in these cells has been lacking. We have used high-speed pressure clamp and elastomeric pillar arrays to apply distinct mechanical stimuli to primary murine chondrocytes, stretch of the membrane and deflection of cell-substrate contacts points, respectively. Both TRPV4 and PIEZO1 channels contribute to currents activated by stimuli applied at cell-substrate contacts but only PIEZO1 mediates stretch-activated currents. These data demonstrate that there are separate, but overlapping, mechanoelectrical transduction pathways in chondrocytes.

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