scholarly journals Bacteria associated with a marine planktonic copepod in culture. I. Bacterial genera in seawater, body surface, intestines and fecal pellets and succession during fecal pellet degradation

1996 ◽  
Vol 18 (2) ◽  
pp. 257-273 ◽  
Author(s):  
Benni Hansen ◽  
Gert Bech
Keyword(s):  
Body Surface ◽  
Fecal Pellet ◽  
Fecal Pellets ◽  
Planktonic Copepod

Peristalsis and propulsion of colonic content can occur after blockade of major neuroneuronal and neuromuscular transmitters in isolated guinea pig colon

2013 ◽  
Vol 305 (12) ◽  
pp. G933-G939 ◽  
Author(s):  
T. C. Sia ◽  
S. J. Brookes ◽  
P. G. Dinning ◽  
D. A. Wattchow ◽  
N. J. Spencer
Keyword(s):  
Guinea Pig ◽  
Nicotinic Receptors ◽  
Fecal Pellet ◽  
Distal Colon ◽  
Fundamental Question ◽  
Fecal Pellets ◽  
Colonic Wall ◽  
Excitatory Neurotransmitters ◽  
Velocity Of Propagation ◽  
Normal Propagation

We recently identified hexamethonium-resistant peristalsis in the guinea pig colon. We showed that, following acute blockade of nicotinic receptors, peristalsis recovers, leading to normal propagation velocities of fecal pellets along the colon. This raises the fundamental question: what mechanisms underlie hexamethonium-resistant peristalsis? We investigated whether blockade of the major receptors that underlie excitatory neuromuscular transmission is required for hexamethonium-resistant peristalsis. Video imaging of colonic wall movements was used to make spatiotemporal maps and determine the velocity of peristalsis. Propagation of artificial fecal pellets in the guinea pig distal colon was studied in hexamethonium, atropine, ω-conotoxin (GVIA), ibodutant (MEN-15596), and TTX. Hexamethonium and ibodutant alone did not retard peristalsis. In contrast, ω-conotoxin abolished peristalsis in some preparations and reduced the velocity of propagation in all remaining specimens. Peristalsis could still occur in some animals in the presence of hexamethonium + atropine + ibodutant + ω-conotoxin. Peristalsis never occurred in the presence of TTX. The major finding of the current study is the unexpected observation that peristalsis can occur after blockade of the major excitatory neuroneuronal and neuromuscular transmitters. Also, the colon retained an intrinsic polarity in the presence of these antagonists and was only able to expel pellets in an aboral direction. The nature of the mechanism(s)/neurotransmitter(s) that generate(s) peristalsis and facilitate(s) natural fecal pellet propulsion, after blockade of major excitatory neurotransmitters, at the neuroneuronal and neuromuscular junction remains to be identified.

scholarly journals Effect of the silica content of diatom prey on the production, decomposition and sinking of fecal pellets of the copepod <i>Calanus sinicus</i>

2016 ◽  
Author(s):  
Hongbin Liu ◽  
Chih-Jung Wu
Keyword(s):  
Biogenic Silica ◽  
Fecal Pellet ◽  
Grazing Rate ◽  
Silica Content ◽  
High Concentration ◽  
Calanus Sinicus ◽  
Fecal Pellets ◽  
Prey Concentration ◽  
Pellet Production ◽  
High Silica

Abstract. The effects of changing the amount of silica in the cell wall of diatom prey, on the production, decomposition rate and sinking velocity of fecal pellets of the calanoid copepod, Calanus sinicus, were examined. Using different light intensities to control the growth of the diatom Thalassiosira weissflogii also led to the accumulation of different amounts of biogenic silica. Copepods were then fed with either low (~ 1600 cells L−1) or high (~ 8000 cells L−1) concentrations of this diatom. Copepods fed on a high concentration of diatoms with high silica content, exhibited a lower grazing rate and lower fecal pellet production rate than those fed on a high concentration of diatoms with low silica content. However, there was no difference in either the grazing or fecal pellet production rates at low prey concentrations with high or low silica content. The size of the fecal pellets produced was only affected by the prey concentration, and not by the silica content of prey. In addition, the degradation rate of the fecal pellets was much higher for copepods fed a low-silica diet than for those fed on a high-silica diet. Significantly lower densities and sinking rates only occurred in the fecal pellets of copepods fed a low-silica diet and a low prey concentration. Calculating the L-ratio (the ratio of degradation rate:sinking rate) for each group indicated that the fecal pellets produced by copepods fed on highly silicified diatoms are likely to transport both biogenic silica and organic carbon to the deep layer; whereas those produced following the consumption of low-silica diatoms are likely to decompose in the mixing layer.

Peristalsis and fecal pellet propulsion do not require nicotinic, purinergic, 5-HT3, or NK3 receptors in isolated guinea pig distal colon

2010 ◽  
Vol 298 (6) ◽  
pp. G952-G961 ◽  
Author(s):  
Sarah Nicholas ◽  
Nick J. Spencer
Keyword(s):  
Guinea Pig ◽  
Propagation Velocity ◽  
Fecal Pellet ◽  
Distal Colon ◽  
Inhibitory Effect ◽  
Propulsive Force ◽  
Fecal Pellets ◽  
Spatiotemporal Mapping ◽  
Direct Contrast ◽  
Mapping Techniques

The neuronal mechanism by which distension of the colon triggers peristalsis and the propulsion of colonic contents is incompletely understood. In this study, we used video imaging and spatiotemporal mapping techniques to investigate the neuroneuronal mechanisms underlying peristalsis in isolated guinea pig distal colon. In direct contrast to previous studies, we found that hexamethonium (100 μM–1 mM) or mecamylamine (20 μM) never abolished peristalsis or fecal pellet propulsion, although a temporary blockade of peristalsis was common, giving the impression perhaps that peristalsis was blocked permanently. During the initiation of peristalsis, the intraluminal propulsive force applied to an inserted fecal pellet was significantly reduced by hexamethonium 100 μM, even though, once initiated, the propagation velocity of fecal pellets was never reduced by nicotinic antagonists. In the presence of hexamethonium or mecamylamine, further addition of PPADS (10 μM), ondansetron (1 μM), and SR 142801 (300 nM) had no inhibitory effect on the propagation velocity of fecal pellets. In these preparations, antagonists for nicotinic, purinergic (P2), serotonergic (5-HT3), or tachykinergic (NK3) receptors always abolished responses to the agonists for these receptors, confirming that when peristalsis occurred, nicotinic, P2, 5-HT3, and NK3 receptors were blocked. Tetrodotoxin abolished nonnicotinic peristalsis. In summary, nicotinic transmission contributes to excitatory neuroneuronal transmission underlying peristalsis and fecal pellet propulsion but is not required for peristalsis, nor fecal pellet propulsion, as once thought. These observations could be explained by an excitatory nonnicotinic neuroneuronal pathway that can generate peristalsis and induce normal fecal pellet propagation velocities but does not require nicotinic, P2, 5-HT3, or NK3 receptors.

Microbiological Survey of Selected Imported Spices and Associated Fecal Pellet Specimens

1989 ◽  
Vol 72 (4) ◽  
pp. 632-637 ◽  
Author(s):  
Felicia B Satchell ◽  
Verneal R Bruce ◽  
Geraldine Allen ◽  
Wallace H Andrews ◽  
Harriet R Gerber
Keyword(s):  
Fecal Pellet ◽  
Test Sample ◽  
Plate Count ◽  
Most Probable Number ◽  
Fecal Pellets ◽  
Probable Number ◽  
E Coli ◽  
Black And White ◽  
Apparent Relationship ◽  
Aerobic Plate Count

Abstract A microbiological survey was performed on 4 selected imported spices: black peppercorns, white peppercorns, coriander, and fennel seed. Aerobic plate count values ranged from 104 to 107 colonyforming units (CFU)/g for black and white peppercorns and from 103 to 105 CFU/g for coriander and fennel seed. Combined results of the 3-tube most probable number procedure and the API 20E kit indicated the presence of Escherichia coli in 4 test samples of black peppercorns, 1 test sample of white peppercorns, and 1 test sample of coriander. Two test samples of black peppercorns were positive for Salmonella contamination. Among the various Enterobacteriaceae isolated from the spices, Enterobacter cloacae and Klebsiella pneumoniae were found most frequently in all spice types. Of 18 mammalian and avian fecal pellets removed from the spices and analyzed microbiologically, E. coli was found in only 2 pellet specimens. There was no apparent relationship between the enteric microflora found in spices and those found in the fecal pellets.

Herbivore Diet Affects Fecal Pellet Settling

1980 ◽  
Vol 37 (9) ◽  
pp. 1352-1357 ◽  
Author(s):  
P. K. Bienfang
Keyword(s):  
Transfer Rate ◽  
Unit Area ◽  
Fecal Pellet ◽  
Mathematical Treatment ◽  
Zooplankton Grazing ◽  
Rate Model ◽  
Fecal Pellets ◽  
Sinking Rate ◽  
Herbivorous Zooplankton ◽  
Excess Density

The sinking rates of fecal pellets produced by herbivorous zooplankton grazing upon phytoplankton stocks composed primarily of diatoms and flagellates were studied and found to be significantly (P < 0.01) different. Under diatom diet, fecal pellets of Calanus sp. showed ranges of volume and sinking rate of 0.38–2.51∙106 μm3 and 70–171 m∙d−1, respectively; under flagellate-based diet the pellet volumes and sinking rates ranged from 0.42 to 3.52∙106 μm3 and 51 to 152 m∙d−1, respectively. Sinking rates for the two sets of fecal pellets were related to compositional density, and significantly (P < 0.01) correlated with the excess density (Δρ = ρp − ρsw) between the particle and the fluid. No significant (P < 0.05) correlation was found between the sinking rates and volumes of fecal pellets examined in these two sets. Calculated pellet densities (ρp) under diatom and flagellate-based nutrition averaged 1.174 and 1.114 g∙cm−3, and conferred average sinking rates of 123.3 and 87.9 m∙d−1, respectively. A mathematical treatment of the functional parameters relevant to the vertical flux of excretory materials is presented, and by application of steady-state turnover theory, provides a framework to estimate the downward transfer rate per unit area of any given pellet constituent considered.Key words: fecal pellets, herbivorous zooplankton, Calanus, nutrition, sinking rate, model

scholarly journals Effect of the silica content of diatom prey on the production, decomposition and sinking of fecal pellets of the copepod <i>Calanus sinicus</i>

2016 ◽  
Vol 13 (16) ◽  
pp. 4767-4775 ◽  
Author(s):  
Hongbin Liu ◽  
Chih-Jung Wu
Keyword(s):  
Biogenic Silica ◽  
Fecal Pellet ◽  
Grazing Rate ◽  
Silica Content ◽  
High Concentration ◽  
Calanus Sinicus ◽  
Fecal Pellets ◽  
Prey Concentration ◽  
Pellet Production ◽  
High Silica

Abstract. The effects of changing the amount of silica in the cell wall of diatom prey, on the production, decomposition rate and sinking velocity of fecal pellets of the calanoid copepod, Calanus sinicus, were examined. Using different light intensities to control the growth of the diatom Thalassiosira weissflogii also led to the accumulation of different amounts of biogenic silica. Copepods were then fed either low ( ∼  1600 cells L−1) or high ( ∼  8000 cells L−1) concentrations of this diatom. Copepods fed a high concentration of diatoms with high-silica content exhibited a lower grazing rate and lower fecal pellet production rate than those fed a high concentration of diatoms with low-silica content. However, there was no difference in either the grazing or fecal pellet production rates at low prey concentrations with high- or low-silica content. The size of the fecal pellets produced was only affected by the prey concentration, and not by the silica content of prey. In addition, the degradation rate of the fecal pellets was much higher for copepods fed a low-silica diet than for those fed a high-silica diet. Significantly lower densities and sinking rates only occurred in the fecal pellets of copepods fed a low-silica diet and a low prey concentration. Calculating the L ratio (the ratio of degradation rate : sinking rate) for each group indicated that the fecal pellets produced by copepods fed highly silicified diatoms are likely to transport both biogenic silica and organic carbon to the deep layer, whereas those produced following the consumption of low-silica diatoms are likely to decompose in the mixing layer.

Three-Dimensional Reconstruction of Native Androctonus Australis Hemocyanin

1990 ◽  
Vol 48 (1) ◽  
pp. 452-453
Author(s):  
Nicolas Boisset ◽  
Jean-Christophe Taveau ◽  
Jean Lamy ◽  
Terence Wagenknecht ◽  
Michael Radermacher ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Body ◽  
Body Surface ◽  
Three Dimensional ◽  
Staining Technique ◽  
Three Dimensional Reconstruction ◽  
Dimensional Reconstruction ◽  
View Reconstruction ◽  
Surface Representations ◽  
Top View

Hemocyanin, the respiratory pigment of the scorpion Androctonus australis is composed of 24 kidney shaped subunits. A model of architecture supported by many indirect arguments has been deduced from electron microscopy (EM) and immuno-EM. To ascertain, the disposition of the subunits within the oligomer, the 24mer was submitted to three-dimensional reconstruction by the method of single-exposure random-conical tilt series.A sample of native hemocyanin, prepared with the double layer negative staining technique, was observed by transmisson electron microscopy under low-dose conditions. Six 3D-reconstructions were carried out indenpendently from top, side and 45°views. The results are composed of solid-body surface representations, and slices extracted from the reconstruction volume.The main two characters of the molecule previously reported by Van Heel and Frank, were constantly found in the solid-body surface representations. These features are the presence of two different faces called flip and flop and a rocking of the molecule around an axis passing through diagonnally opposed hexamers. Furthermore, in the solid-body surface of the top view reconstruction, the positions and orientations of the bridges connecting the half molecules were found in excellent agreement with those predicted by the model.

Sign in / Sign up

Export Citation Format

Share Document