Mass Transfer Performance of a Marine Zooplankton Olfactometer

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Ahmed A. Alkhafaji ◽  
Osama M. Selim ◽  
Ryoichi S. Amano ◽  
J. R. Strickler ◽  
P. Hinow ◽  
...  
Keyword(s):  
Host Finding ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
3 Dimensional ◽  
Marine Zooplankton ◽  
Chemical Gradients ◽  
Fluid Physics ◽  
Flow Domain ◽  
Chemical Distribution ◽  
Gnathiid Isopod

Abstract By adopting different methods to the inlet of a zooplankton olfactometer, the current study investigates the effect of the energy of chemical flow on the Gnathiid isopod crustaceans predicted behavior. These are mobile external parasites of fishes that have a significant impact on the health of their hosts. They rely at least in part on olfactory cues to find the host fish. To better understand host-finding dynamics in these parasites, a study was conducted with the simulations as a blueprint for developing a 3-dimensional test apparatus similar to what has been used for studying olfactory orientation in insects. The simulated olfactometer has four legs, each leg forming an inlet where fluids are introduced into the flow domain. There is one outlet at the center of the device. A mixture of water and chemicals is presented by applying a multi-component system. The shear and chemical concentration distribution were conducted to see how fluid physics plays a role in creating a chemical landscape. Computational results show distinct regions separated by high chemical concentration gradients when introducing chemicals from one leg. Changing the fluid inflow from one common inlet to three inlets shows that the chemical distribution exhibits steeper gradients than the typical inlet case, depicting that the gradual chemical concentrations can drive the animal toward the target faster. The best behavior that gives higher chemical gradients is obtained through the study when using three sub-inlets and Schmidt number between 3 and 10.

scholarly journals Distinct nitrogen cycling and steep chemical gradients in Trichodesmium colonies

2019 ◽  
Vol 14 (2) ◽  
pp. 399-412 ◽  
Author(s):  
Isabell Klawonn ◽  
Meri J. Eichner ◽  
Samuel T. Wilson ◽  
Nasrollah Moradi ◽  
Bo Thamdrup ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Nitrate Concentration ◽  
Concentration Gradients ◽  
Ambient Seawater ◽  
N Transformations ◽  
Isotope Tracer ◽  
Chemical Gradients ◽  
Nitrate Consumption ◽  
N Compounds ◽  
Numeric Modelling

Abstract Trichodesmium is an important dinitrogen (N2)-fixing cyanobacterium in marine ecosystems. Recent nucleic acid analyses indicate that Trichodesmium colonies with their diverse epibionts support various nitrogen (N) transformations beyond N2 fixation. However, rates of these transformations and concentration gradients of N compounds in Trichodesmium colonies remain largely unresolved. We combined isotope-tracer incubations, micro-profiling and numeric modelling to explore carbon fixation, N cycling processes as well as oxygen, ammonium and nitrate concentration gradients in individual field-sampled Trichodesmium colonies. Colonies were net-autotrophic, with carbon and N2 fixation occurring mostly during the day. Ten percent of the fixed N was released as ammonium after 12-h incubations. Nitrification was not detectable but nitrate consumption was high when nitrate was added. The consumed nitrate was partly reduced to ammonium, while denitrification was insignificant. Thus, the potential N transformation network was characterised by fixed N gain and recycling processes rather than denitrification. Oxygen concentrations within colonies were ~60–200% air-saturation. Moreover, our modelling predicted steep concentration gradients, with up to 6-fold higher ammonium concentrations, and nitrate depletion in the colony centre compared to the ambient seawater. These gradients created a chemically heterogeneous microenvironment, presumably facilitating diverse microbial metabolisms in millimetre-sized Trichodesmium colonies.

scholarly journals Electrolyte Metabolism in HeLa Cells

1963 ◽  
Vol 46 (6) ◽  
pp. 1303-1315 ◽  
Author(s):  
Margaret Wickson-ginzburg ◽  
A. K. Solomon
Keyword(s):  
Transport System ◽  
Hela Cells ◽  
Generation Time ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
K Uptake ◽  
Initial Value ◽  
Electrolyte Metabolism ◽  
K Cells ◽  
Low K

Methods have been developed to study cellular Na, K, and Cl concentrations in HeLa cells. Cell [Na] and [K] are functions of the age of the culture. As the culture grows [K], expressed in mmols/liter cell H2O, rises from an initial value of 121 to a peak of 206 at about 4 days, and thereafter falls until it has almost returned to the initial value by the 9th day. [Na] falls as [K] rises, but there is no fixed relationship between the cellular concentrations of the two cations. There is, however, a correlation between generation time and cellular [K]. Measurements of net K uptake and net Na extrusion were carried out during 1 hour incubation at 37°C of low K cells. Both net K uptake and net Na extrusion took place against chemical concentration gradients, so that at least one transport system must be active; if the Cl distribution is passive both net K uptake and net Na extrusion are active. Studies with inhibitors of respiration and glycolysis lead to the conclusion that respiration is not required for these net transports, which appear to derive their energy from glycolytic sources.

scholarly journals Navigation within host tissues: cues for orientation of Diplostomum spathaceum (Trematoda) in fish towards veins, head and eye

Parasitology ◽  
2007 ◽  
Vol 134 (7) ◽  
pp. 1013-1023 ◽  
Author(s):  
W. HAAS ◽  
C. WULFF ◽  
K. GRABE ◽  
V. MEYER ◽  
S. HAEBERLEIN
Keyword(s):  
Blood Vessels ◽  
Skin Surface ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
Diplostomum Spathaceum ◽  
Preliminary Model ◽  
Molecular Fraction ◽  
Arginine Residues ◽  
Fish Fins ◽  
Host Tissues

SUMMARYCercariae of Diplostomum spathaceum penetrate the skin of fish, and then migrate along blood vessels and tissues towards the head and the eye-lens. We studied their orientation behaviour in tail fins of guppies and in chemical concentration gradients within agar-filled choice chambers. In fins, they entered veins and orientated cranially, independent of the blood flow and living cells. In choice chambers, they were attracted by a small molecular fraction of fish serum, D-glucose (at 1, 10, and 1000 μm), D-mannose, D-maltotriose and Cl-ions, whereas D-glucosamine repelled them (even at 1·0 nm). Amino acids were not attractive, but arginine in tetrapeptides attracted at concentrations as low as 1 μm and melatonin at 0·4–4·3 pm. We suggest a preliminary model for the behaviour of diplostomula in fish fins and attracting (+) or repelling (−) host cues: (1) migration towards deeper skin layers and avoidance of skin surface, cues: Cl-ions (+ and −), glucose (+), glucosamine (−), light radiation (−); (2) orientation in cranial direction, cue: Cl-ions (+); (3) localization of blood vessels, cues: glucose (+), arginine-residues (+); (4) localization of the retina, cue: melatonin (+). A comparison with the navigation mechanisms of tissue-migrating schistosomules and hookworm larvae reveals an enormous diversity of strategies.

scholarly journals Application of an online ion-chromatography-based instrument for gradient flux measurements of speciated nitrogen and sulfur

2016 ◽  
Vol 9 (6) ◽  
pp. 2581-2592 ◽  
Author(s):  
Ian C. Rumsey ◽  
John T. Walker
Keyword(s):  
Ion Chromatography ◽  
Concentration Gradient ◽  
Sampling Site ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Chemical Concentration ◽  
Concentration Gradients ◽  
Transfer Velocity ◽  
Surface Exchange ◽  
Chemical Concentration Gradient

Abstract. The dry component of total nitrogen and sulfur atmospheric deposition remains uncertain. The lack of measurements of sufficient chemical speciation and temporal extent make it difficult to develop accurate mass budgets and sufficient process level detail is not available to improve current air–surface exchange models. Over the past decade, significant advances have been made in the development of continuous air sampling measurement techniques, resulting with instruments of sufficient sensitivity and temporal resolution to directly quantify air–surface exchange of nitrogen and sulfur compounds. However, their applicability is generally restricted to only one or a few of the compounds within the deposition budget. Here, the performance of the Monitor for AeRosols and GAses in ambient air (MARGA 2S), a commercially available online ion-chromatography-based analyzer is characterized for the first time as applied for air–surface exchange measurements of HNO3, NH3, NH4+, NO3−, SO2 and SO42−. Analytical accuracy and precision are assessed under field conditions. Chemical concentrations gradient precision are determined at the same sampling site. Flux uncertainty measured by the aerodynamic gradient method is determined for a representative 3-week period in fall 2012 over a grass field. Analytical precision and chemical concentration gradient precision were found to compare favorably in comparison to previous studies. During the 3-week period, percentages of hourly chemical concentration gradients greater than the corresponding chemical concentration gradient detection limit were 86, 42, 82, 73, 74 and 69 % for NH3, NH4+, HNO3, NO3−, SO2 and SO42−, respectively. As expected, percentages were lowest for aerosol species, owing to their relatively low deposition velocities and correspondingly smaller gradients relative to gas phase species. Relative hourly median flux uncertainties were 31, 121, 42, 43, 67 and 56 % for NH3, NH4+, HNO3, NO3−, SO2 and SO42−, respectively. Flux uncertainty is dominated by uncertainty in the chemical concentrations gradients during the day but uncertainty in the chemical concentration gradients and transfer velocity are of the same order at night. Results show the instrument is sufficiently precise for flux gradient applications.

Ring closure dynamics for a chemically active polymer

Soft Matter ◽  
2014 ◽  
Vol 10 (47) ◽  
pp. 9577-9584 ◽  
Author(s):  
Debarati Sarkar ◽  
Snigdha Thakur ◽  
Yu-Guo Tao ◽  
Raymond Kapral
Keyword(s):  
Long Range ◽  
Chemical Reaction ◽  
Polymer Chains ◽  
Ring Closure ◽  
Chemical Concentration ◽  
Loop Formation ◽  
Concentration Gradients

Our studies on ring closure of polymer showed how the long-range nature of the chemical concentration gradients, self-generated by the presence of a catalytic bead on which a chemical reaction occurs, could cause a distant bead to chemotactically move towards to the source of the gradient. Such chemically-active polymers hence undergo ring closure or loop formation more rapidly than inactive polymer chains.

Finding and recognition of the snail intermediate hosts by 3 species of echinostome cercariae

Parasitology ◽  
1995 ◽  
Vol 110 (2) ◽  
pp. 133-142 ◽  
Author(s):  
W. Haas ◽  
M. Körner ◽  
E. Hutterer ◽  
M. Wegner ◽  
B. Haberl
Keyword(s):  
Viscoelastic Properties ◽  
Organic Molecules ◽  
Host Finding ◽  
Intermediate Hosts ◽  
Amino Groups ◽  
Concentration Gradients ◽  
Small Peptides ◽  
Small Molecular Weight ◽  
First Intermediate Host ◽  
Host Cues

SUMMARYFinding and recognition of snail second intermediate hosts was studied in cercariae of 3 echinostome species. The cercariae of the 3 species accumulated in snail-conditioned water (SCW) with 2 types of orientation mechanisms and responded to different small molecular weight (< 500 Da) components of SCW. Pseudechinoparyphium echinatum and Echinostoma revolutum cercariae returned by swimming an arc, when swimming in decreasing concentration gradients of SCW (turnback swimming). The stimulating cues of SCW were identified as hydrophilic organic molecules, probably posessing amino groups. Amino acids contributed to the attractivity of SCW, at least in P. echinatum, but they could not account for the complete attractivity of SCW. Hypoderaeum conoideum were directed chemotactically and swam along increasing concentration gradients of small peptides within SCW, but in decreasing SCW gradients they showed no turn-back swimming. Chemotactic orientation in H. conoideum only started 1 h after emission, which may assist the cercariae to leave the immediate area of their first intermediate host snails and to disperse. Attachments occurred specifically to snail hosts in the 3 species and were stimulated by macromolecular mucus compounds, probably mainly by viscoelastic properties of the mucus. The results of this study show, that host-finding mechanisms and the stimulating host cues of snail invading echinostome cercariae differ considerably from those of schistosome miracidia.

scholarly journals The fluid physics of signal perception by mate-tracking copepods

1998 ◽  
Vol 353 (1369) ◽  
pp. 787-804 ◽  
Author(s):  
Jeannette Yen ◽  
Marc J. Weissburg ◽  
Michael H. Doall
Keyword(s):  
Molecular Diffusion ◽  
Reaction Times ◽  
Small Scale ◽  
Threshold Detection ◽  
Marine Copepod ◽  
Signal Perception ◽  
Chemical Gradients ◽  
Fluid Physics ◽  
Temora Longicornis ◽  
Order Of Magnitude

Within laboratory–induced swarms of the marine copepod Temora longicornis , the male exhibits chemically mediated trail–following behaviour, concluding with fluid mechanical provocation of the mate–capture response. The location and structure of the invisible trail were determined by examining the specific behaviour of the female copepods creating the signal, the response of the male to her signal, and the fluid physics of signal persistence. Using the distance of the mate–tracking male from the ageing trail of the female, we estimated that the molecular diffusion coefficient of the putative pheromonal stimulant was 2.7 times –5 cm 2 s –1 , or 1000 times slower than the diffusion of momentum. Estimates of signal strength levels, using calculations of diffusive properties of odour trails and attenuation rates of fluid mechanical signals, were compared to the physiological and behavioural threshold detection levels. Males find trails because of strong across–plume chemical gradients; males sometimes go the wrong way because of weak along–plume gradients; males lose the trail when the female hops because of signal dilution; and mate–capture behaviour is elicited by suprathreshold flow signals. The male is stimulated by the female odour to accelerate along the trail to catch up with her, and the boundary layer separating the signal from the chemosensitive receptors along the copepod antennule thins. Diffusion times, and hence reaction times, shorten and behavioural orientation responses can proceed more quickly. While ‘perceptive’ distance to the odour signal in the trail or the fluid mechanical signal from the female remains within 1 to 2 body lengths (< 5 mm), the ‘reactive’ distance between males and females was an order of magnitude larger. Therefore, when nearest–neighbour distances are 5 cm or less, as in swarms of 10 4 copepods m –3 , mating events are facilitated. The strong similarity in the structure of mating trails and vortex tubes (isotropic, millimetre—centimetre scale, 10:1 aspect ratio, 10 s persistence), indicates that these trails are constrained by the same physical forces that influence water motion in a low Reynolds number fluid regime, where viscosity limits forces to the molecular scale. The exploratory reaches of mating trails appear inscribed within Kolmogorov eddies and may represent a measure of eddy size. Biologically formed mating trails, however, are distinct in their flow velocity and chemical composition from common small–scale turbulent features; and mechanoreceptive and chemoreceptive copepods use their senses to discriminate these differences. Zooplankton are not aimless wanderers in a featureless environment. Their ambit is replete with clues that guide them in their efforts for survival in the ocean.

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