Effects of nutritional status on cyanobacterial buoyancy, blooms, and dominance, with special reference to inorganic carbon

1991 ◽  
Vol 69 (5) ◽  
pp. 1133-1138 ◽  
Author(s):  
Andrew R. Klemer
Keyword(s):  
Nutritional Status ◽  
Laboratory Experiments ◽  
Inorganic Carbon ◽  
Nutrient Deficiency ◽  
Gas Vesicles ◽  
Surface Layers ◽  
Key Words Cyanobacteria ◽  
Water Columns ◽  
Different Types ◽  
Correlative Studies

Evidence from correlative studies suggesting that nutrient deficiency is responsible for cyanobacterial surface blooms is contrasted with evidence from lake and laboratory experiments suggesting that the ability of cyanobacterial populations to monopolize light in the surface layers of stratified water columns depends on the availability of nutrients required for gas-vesicle synthesis as well as for growth. A resolution of the paradoxical roles of inorganic carbon in cyanobacterial buoyancy regulation is advanced and is used to explain the success of different types of cyanobacteria in environments that differ greatly in bicarbonate content. Key words: cyanobacteria, gas vesicles, buoyancy, blooms, dominance, bicarbonate.

scholarly journals Autophagy Modulators in Cancer Therapy

2021 ◽  
Vol 22 (11) ◽  
pp. 5804
Author(s):  
Kamila Buzun ◽  
Agnieszka Gornowicz ◽  
Roman Lesyk ◽  
Krzysztof Bielawski ◽  
Anna Bielawska
Keyword(s):  
Cancer Research ◽  
Cancer Therapy ◽  
Adverse Effects ◽  
Nutrient Deficiency ◽  
Molecular Regulation ◽  
Regulatory Pathways ◽  
Selective Autophagy ◽  
Atg Proteins ◽  
Different Types ◽  
The Relationship

Autophagy is a process of self-degradation that plays an important role in removing damaged proteins, organelles or cellular fragments from the cell. Under stressful conditions such as hypoxia, nutrient deficiency or chemotherapy, this process can also become the strategy for cell survival. Autophagy can be nonselective or selective in removing specific organelles, ribosomes, and protein aggregates, although the complete mechanisms that regulate aspects of selective autophagy are not fully understood. This review summarizes the most recent research into understanding the different types and mechanisms of autophagy. The relationship between apoptosis and autophagy on the level of molecular regulation of the expression of selected proteins such as p53, Bcl-2/Beclin 1, p62, Atg proteins, and caspases was discussed. Intensive studies have revealed a whole range of novel compounds with an anticancer activity that inhibit or activate regulatory pathways involved in autophagy. We focused on the presentation of compounds strongly affecting the autophagy process, with particular emphasis on those that are undergoing clinical and preclinical cancer research. Moreover, the target points, adverse effects and therapeutic schemes of autophagy inhibitors and activators are presented.

scholarly journals Some chemical and bacterial characteristics of bottom deposits from lakes and estuaries

1953 ◽  
Vol 51 (2) ◽  
pp. 185-194 ◽  
Author(s):  
L. A. Allen ◽  
J. Grindley ◽  
Eileen Brooks
Keyword(s):  
Bacteriological Examination ◽  
Surface Layers ◽  
Digested Sludge ◽  
Faecal Pollution ◽  
Bottom Deposits ◽  
Low Concentrations ◽  
Different Types ◽  
Different Depths ◽  
Micro Organisms ◽  
Reducing Bacteria

Chemical and bacteriological examination of muds from sources differing widely in the degree of pollution to which they were subject showed great differences in the contents of carbon, nitrogen and sulphide. These differences were not correlated with differences in the severity of faecal pollution. The amount of organic matter available for growth of micro-organisms in the mud of different depths was not reflected in the figures for organic carbon. A convenient index of this factor was obtained by measuring the volume of gas evolved during anaerobic digestion over a prolonged period of incubation. The rate of evolution was increased by the addition of an inoculum of digested sludge from a sewage works.Sulphate-reducing bacteria appeared to be of two different types. In samples of mud from fresh-water lakes much higher counts were usually obtained in a medium containing comparatively low concentrations of inorganic salts and of lactate than in a medium containing much higher concentrations of these constituents. In samples from locations where conditions were more saline the reverse was usually true.Counts of Bact. coli and of Strep, faecalis together probably constitute the best index of faecal pollution in the examination of samples of mud. These organisms are, however, largely confined to the surface layers.

scholarly journals Competitive interactions between species of freshwater snails: I. Laboratory: Ia. General methodology

1983 ◽  
Vol 78 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Frederico Simões Barbosa ◽  
Dirceu P. Pereira da Costa ◽  
Francisco Arruda
Keyword(s):  
Laboratory Experiments ◽  
Freshwater Snail ◽  
Current Paper ◽  
Competitive Interactions ◽  
Laboratory Work ◽  
Freshwater Snails ◽  
Technical Advance ◽  
General Methodology ◽  
Different Types ◽  
Set Up

For the development of laboratory experiments on the competitive interacitons between freshwater snail populations, special snail rooms were set up in the main building of the Research Center "Aggeu Magalhães". In the current paper, the first of a series on this subject, the general methodology of the laboratory work is described in detail. Using indoor cement channels in which a uniform seminatural environment was created, interactions of freshwater snail populations can be studied with minimal interference of the usual variables. Controlled indoor environmental techniques, as described in the current paper, may also be utilized in different types of experiments in malacology, and represent a substantial technical advance in malacological work.

Active HCO3− transport in cyanobacteria

1991 ◽  
Vol 69 (5) ◽  
pp. 936-944 ◽  
Author(s):  
George S. Espie ◽  
Anthony G. Miller ◽  
Ramani A. Kandasamy ◽  
David T. Canvin
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Reaction Medium ◽  
Transport Systems ◽  
Bicarbonate Transport ◽  
Key Words Cyanobacteria ◽  
Sodium Dependent ◽  
Rate Of Photosynthesis ◽  
Low Levels ◽  
In Cells

Cyanobacteria possess systems for the active transport of both CO2 and HCO3−. While the active CO2 transport system seems to be present in cells grown on all levels of CO2 or dissolved inorganic carbon, the bicarbonate transport systems are only present in cells grown on low levels of CO2 or dissolved inorganic carbon (air levels or lower). Active bicarbonate transport can be shown to occur when the rate of photosynthesis exceeds that which could be sustained by the production of CO2 from the dehydration of bicarbonate or when CO2 transport is inhibited with carbon oxysulfide or hydrogen sulfide. Two systems for active bicarbonate transport have been identified: one is dependent on the presence of millimolar concentrations of sodium, and the other is independent of the sodium requirement. Cells grown with air bubbling normally possess the first whereas cells grown in standing culture normally possess the second. The sodium-dependent bicarbonate transport can be inhibited by omitting sodium from the reaction medium or competitively with lithium when sodium is present. Monensin and amiloride also inhibit sodium-dependent bicarbonate transport. It does not appear to be inhibited by ethoxyzolamide. The inhibition of sodium-independent bicarbonate transport is not yet established. Bicarbonate transport appears to have no effect on CO2 transport and CO2 transport appears to have no effect on bicarbonate transport. Hence, the transport systems seems to be independent. Although a number of mechanisms have been proposed for bicarbonate transport, the experimental data are not sufficient to clearly distinguish between them. Key words: cyanobacteria, active CO2 transport, active HCO3− transport, photosynthesis, sodium.

scholarly journals The Role of Gastrolites on Feeding Behavior and Digestive Efficiency in the Rufous-Collared Sparrow

The Condor ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 465-469
Author(s):  
M. Victoria LÓpez-Calleja ◽  
Mauricio Soto-Gamboa ◽  
Enrico L. Rezende
Keyword(s):  
Digestive Tract ◽  
Laboratory Experiments ◽  
Morphological Changes ◽  
Digestive Efficiency ◽  
Accidental Ingestion ◽  
Energy Demands ◽  
Zonotrichia Capensis ◽  
Different Types ◽  
Voluntary Behavior

Abstract We examined grit consumption in the facultative granivorous Rufous-collared Sparrow (Zonotrichia capensis). Grit consumption fluctuated seasonally and was significantly correlated with morphological changes in the digestive tract, and with seed size. The highest values of grit consumption and digestive tract mass were observed during winter. Laboratory experiments suggested that grit consumption was a voluntary behavior rather than the result of accidental ingestion, and favored digestibility. Grit consumption varied considerably when Z. capensis fed on different types of food, but remained constant when food availability varied. We suggest that grit consumption together with morphological changes in the digestive tract allow Z. capensis to increase energy acquisition in response to higher energy demands during wintertime.

Effects of several water quality parameters on arsenic removal by coagulation: laboratory experiments and a pilot-scale study

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
D. Laky ◽  
B. László ◽  
I. Licskó
Keyword(s):  
Potassium Permanganate ◽  
Ferric Chloride ◽  
Laboratory Experiments ◽  
Inorganic Carbon ◽  
Arsenic Removal ◽  
Research Work ◽  
Arsenic Concentration ◽  
Pilot Scale ◽  
Organic Content ◽  
Manganese Concentration

In laboratory experiments a traditional drinking water treatment method, coagulation/flocculation followed by solid/liquid phase separation has been applied in order to decrease arsenic concentration below 10 μg/L (which is the new Hungarian standard for arsenic). The goal of the research work was to examine the transition of the dissolved arsenic to solid form, to determine the factors which have significant effect on arsenic removal efficiency. The organic content of the water highly affected the arsenic removal process. The difference in the required coagulant dosage can be order of one magnitude depending on the organic content of the water. The phosphorous content also increases the required coagulant dose, since ferric phosphate precipitates are formed, decreasing the amount of coagulant available for arsenic removal. pH also proved to have significant influence when experiments were carried out at wide pH range. However, under more realistic conditions (pH is between 7.5 and 8), the effect of pH was not that significant. The inorganic carbon content at some extent favors the liquid/solid transition of arsenate, since it contributes to the buffering capacity of the water, therefore enhances the metal hydroxide formation process. However, the excess inorganic carbon has disadvantageous effect, since it competes with the arsenate ions for the free sites of metal hydroxides. Two oxidants (chlorine and potassium permanganate) and two coagulants (ferric chloride and aluminum sulfate) were studied in pilot scale experiments. The pilot plant was operated at Hajdúbagos, where the arsenic, iron and manganese concentration of the raw water is above the standard. In the experiments it was found the potassium permanganate + ferric chloride combination was the most efficient.

A Programme of Laboratory Experiments to Aid the Teaching of Wave Phenomena to Foundation Year in Engineering Students

1996 ◽  
Vol 33 (1) ◽  
pp. 27-38
Author(s):  
W. Booth
Keyword(s):  
Laboratory Experiments ◽  
Engineering Students ◽  
Physical Optics ◽  
Different Types ◽  
Potential Applications ◽  
Wave Phenomena

A laboratory programme of experiments to assist the teaching of wave phenomena to Engineering Foundation Year students A programme of experiments targeted at Engineering Foundation Year students and aimed at illustrating the important properties and potential applications of different types of waves, including sound, ultrasonics, waves on stretched springs, physical optics and UHF radio transmission is described and discussed.

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