Surface Forces in the Tracheal System of Insects

1953 ◽  
Vol s3-94 (28) ◽  
pp. 507-522
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Salt Water ◽  
Swelling Pressure ◽  
Secretory Activity ◽  
Ion Concentration ◽  
Mosquito Larvae ◽  
Tracheal System ◽  
Hydrogen Ion Concentration ◽  
A Cell ◽  
Physical Forces ◽  
Anal Papillae

The mechanism by which the tracheal system becomes filled with air is reviewed. It is concluded that the fluid contents are actively absorbed by the walls of the system. The air often enters from the atmosphere through the spiracles. In some insects the system fills while the insect is submerged in water or while the spiracles are closed. It is shown by means of simple models how the tanning of the lining of the larger tracheae or the secretion of wax over the walls will bring about the liberation of gas from solution when the fluid is subjected to a very slight negative pressure. The movements of fluid in the tracheole endings of insects are also reviewed. The removal of fluid which takes place during activity, particularly under conditions of deficient oxygen supply, is not caused by secretory activity but by the physical forces produced by the products of metabolism. The evidence supports the view that the fluid in the tracheoles is a cell sap whose passage up the tracheole under the action of capillarity is opposed by the elasticity or swelling pressure of the cytoplasmic sheath of the tracheoles. It is shown by means of a simple gelatin model how osmotic changes in the surrounding fluid, acting by way of a cytoplasmic sheath, will bring about the absorption of such a cell sap. A more exact model, illustrating the greater permeability of the inner wall of the tracheole which the proposed mechanism requires, is provided by the anal papillae of mosquito larvae. These structures show the same adaptation to a saline medium as is postulated in the tracheoles of mosquito larvae from salt water. Alternative mechanisms are discussed. It is suggested that the capillary forces in the tracheoles are probably small. The effects of probable contamination of the tracheole fluid by an oily film (Beament) and the effects of changes in hydrogen-ion concentration on interfacial tensions are illustrated by reference to further models.

Cadmium in the aquatic environment: a review of ecological, physiological, and toxicological effects on biota

1994 ◽  
Vol 2 (2) ◽  
pp. 187-214 ◽  
Author(s):  
D. A. Wright ◽  
P. M. Welbourn
Keyword(s):  
Metal Binding ◽  
Chronic Toxicity ◽  
Field Experiments ◽  
Salt Water ◽  
Global Scale ◽  
Ion Concentration ◽  
Toxicity Tests ◽  
Aquatic Biota ◽  
Cadmium Ion ◽  
Hydrogen Ion Concentration

Cadmium is a nonessential element that can be toxic and carcinogenic. On a global scale, the ratio anthropogenic to natural emissions of cadmium is approximately 7:1. Sources of cadmium for freshwater and salt water include atmospheric deposition, direct and via runoff, as well as direct discharges into water or watersheds. Thirty percent of the atmospheric emissions fall onto water. In freshwater, the cadmium ion is the predominant dissolved form, while in seawater, chloride dominates. Much of the cadmium added to aquatic systems accumulates in sediments where it presents a risk to benthic biota and under certain conditions may reenter the water column. The cadmium ion is the most bioavailable to aquatic biota; factors affecting availability include salinity, dissolved organic matter, and hydrogen ion concentration, which affect the chemical forms of cadmium. Hydrogen and other ions, most notably calcium, also affect cadmium uptake and toxicity, through competition and physiological effects. The concentrations of cadmium that result in acute or chronic toxicity vary over several orders of magnitude, with certain freshwater fish and invertebrates being the most sensitive. Long-term field experiments and chronic toxicity tests on invertebrates suggest that the present Canadian guideline of 200 ng Cd∙L−1 for the protection of freshwater biota may be too high. Aquatic animals and plants, like most organisms, produce metal binding proteins, called metallothioneins, in response to cadmium. Some species or varieties within a species of aquatic biota are tolerant to cadmium. The relationship between cadmium tolerance and metallothionein is still incompletely resolved.Key words: cadmium, seawater, freshwater, availability, toxicity, metallothionein, tolerance, food chain.

scholarly journals The Influence of the Hydrogen-Ion Concentration in the Development of Mosquito Larvae. Preliminary Contribution

Parasitology ◽  
1921 ◽  
Vol 13 (4) ◽  
pp. 348-351 ◽  
Author(s):  
Malcolm E. MacGregor
Keyword(s):  
High Mortality ◽  
Food Supply ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Mosquito Larvae ◽  
Hydrogen Ion Concentration ◽  
Common Experience ◽  
Long Time ◽  
State Of Affairs ◽  
General Opinion

It is a common experience that mosquito larvae when they are brought into a laboratory to undergo their development, often fail to develop normally. At times a high mortality takes place, or the larvae lapse into a condition of suspended development continuing as larvae for months. The latter phase usually ends in death before pupation can take place. I have been puzzled to account for these manifestations for a very long time, and have conducted various experiments in the hope of discovering the cause. The general opinion on the matter, I think, is that there is “something wrong with the food supply,” but as a matter of fact larvae supplied with an ample diet often show the same state of affairs.

scholarly journals ELECTRIFICATION OF WATER AND OSMOTIC PRESSURE

1919 ◽  
Vol 2 (1) ◽  
pp. 87-106 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Osmotic Pressure ◽  
Salt Water ◽  
Pure Water ◽  
Preceding Paper ◽  
Ion Concentration ◽  
Hydrogen Ions ◽  
Hydrogen Ion Concentration ◽  
Positively Charged ◽  
As If ◽  
Charged Water

1. Amphoteric electrolytes form salts with both acids and alkalies. It is shown for two amphoteric electrolytes, Al(OH)3 and gelatin, that in the presence of an acid salt water diffuses through a collodion membrane into a solution of these substances as if its particles were negatively charged, while water diffuses into solutions of these electrolytes, when they exist as monovalent or bivalent metal salts, as if the particles of water were positively charged. The turning point for the sign of the electrification of water seems to be near or to coincide with the isoelectric point of these two ampholytes which is a hydrogen ion concentration of about 2 x 10–5 N for gelatin and about 10–7 for Al(OH)3. 2. In conformity with the rules given in a preceding paper the apparently positively charged water diffuses with less rapidity through a collodion membrane into a solution of Ca and Ba gelatinate than into a solution of Li, Na, K, or NH4 gelatinate of the same concentration of gelatin and of hydrogen ions. Apparently negatively charged water diffuses also with less rapidity through a collodion membrane into a solution of gelatin sulfate than into a solution of gelatin chloride or nitrate of the same concentration of gelatin and of hydrogen ions. 3. If we define osmotic pressure as that additional pressure upon the solution required to cause as many molecules of water to diffuse from solution to the pure water as diffuse simultaneously in the opposite direction through the membrane, it follows that the osmotic pressure cannot depend only on the concentration of the solute but must depend also on the electrostatic effects of the ions present and that the influence of ions on the osmotic pressure must be the same as that on the initial velocity of diffusion. This assumption was put to a test in experiments with gelatin salts for which a collodion membrane is strictly semipermeable and the tests confirmed the expectation.

INVESTIGATION OF BEE BREAD AND DEVELOPMENT OF ITS DOSAGE FORMS

2014 ◽  
Vol 21 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Ilze Barene ◽  
Irena Daberte ◽  
Sanita Siksna
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Potato Starch ◽  
Microscopic Analysis ◽  
Stability Study ◽  
Ion Concentration ◽  
Wet Granulation ◽  
Hydrogen Ion Concentration ◽  
Bee Bread ◽  
Layer Chromatography

The aim of the study. The objective of this study was to investigate microscopic, physical and chemical properties of bee bread collected in three regions of Latvia in order to compare the quality and to investigate the possibility of producing granules containing bee bread. Material and methods. Microscopic analysis of bee bread samples was performed. Plant herbaria, special literature and internet sources were used for identification of pollen. Thin layer chromatography was used for identification of carotenoids and flavonoids. Granules were prepared by wet granulation method. Lactose, calcium lactate, calcium carbonate, potato starch and purified water were used as excipients. Appearance, loss on drying, pH of aqueous solution and content of carotenes were estimated. Results. Microscopic analysis showed mostly native pollen identified as willow pollen. Beta-carotene identified and 2 carotenoids found by thin layer chromatography. Two zones of flavonoids found on chromatograms at day light and 6 zones at ultra violet light. The comparison of bee bread samples of 3 regions of Latvia showed insignificant differences in appearance and consistency, hydrogen ion concentration 3.93–4.23, loss on drying 7.72–11.07 %; content of carotenes calculated to bcarotene 6.77–9.35 mg%. Stability study of bee bread samples showed greater changes after storage at 40ºC temperature. All compositions of granules showed appropriate appearance and flowability. Quality of granules: loss on drying 5.48–13.5%, content of carotenes calculated to b-carotene 5.77–6.75 mg%. Conclusions. Pollen of willow can be considered as an indicator of the origin of bee bread in Latvia. Bee bread samples of three regions of Latvia have insignificant differences in physical, chemical parameters.

Hydro-geochemical properties with respect to landuse in the southernmost river of Kerala

2018 ◽  
Vol 6 (1) ◽  
Author(s):  
Badusha M. ◽  
Santhosh S
Keyword(s):  
Organic Carbon ◽  
Drainage Basin ◽  
Anthropogenic Activities ◽  
Oxygen Demand ◽  
Ion Concentration ◽  
Total Hardness ◽  
Hydrogen Ion Concentration ◽  
Geochemical Properties ◽  
Quality Of Water

The hydro geochemical features of Neyyar River for a period of one year from May 2015 to April 2016 were analyzed. Six sampling sites were fixed considering physiography and present landuse pattern of the river basin. The residents in the drainage basin are primarily responsible for framing a better landuse and thereby maintain a good water and sediment regime. Geospatial pattern of the present landuse of the study area indicated that the sustainability of this river ecosystem is in danger due to unscientific landuse practices, which is reflected in the river quality as well. The parameters such as hydrogen ion concentration, electrical conductivity, chloride, Biological Oxygen Demand, total hardness and sulphate of river water and Organic Carbon of river bed sediments were analyzed in this study. The overall analysis shows that the highland areas are characterized by better quality of water together with low organic carbon, which is mainly due to better landuse and minimal reclamation. The midland and lowland areas are characterized by poor quality of water with high organic carbon, which is due to high anthropogenic activities and maximum pollutants associated with the region together with the alteration in landuse from a traditional eco-friendly pattern to a severely polluted current pattern.

EFFECTS OF SOIL ACIDITY ON RHIZOBIA NUMBERS, NODULATION AND NITROGEN FIXATION BY ALFALFA AND RED CLOVER

1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Soil Acidity ◽  
Field Experiments ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Red Clover ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Greenhouse Experiments

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.

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