Relative Importance of Microbes versus Macroinvertebrate Shredders in the Process of Leaf Decay in Lakes of Differing pH

1993 ◽  
Vol 50 (12) ◽  
pp. 2707-2712 ◽  
Author(s):  
Nancy C. Tuchman
Keyword(s):  
Low Ph ◽  
Decay Rates ◽  
Relative Importance ◽  
Alkaline Lakes ◽  
Acid Lakes ◽  
Leaf Decay ◽  
Effects Of Ph ◽  
Mesh Bags ◽  
Decreasing Ph ◽  
Physical And Chemical

Four nonhumic lakes in northern Michigan, ranging in pH from 4.0 to 8.0, were selected to assess the effects of pH on leaf decay rates, leaf-associated macroinvertebrate assemblages, and the relative importance of microbes and shredders to the leaf decay process. Except for pH (and covariates of pH) these lakes were similar in physical and chemical parameters which directly affect metabolism. Preweighed leaves were placed in all four lakes for 8 wk; half of the leaves were confined in mesh bags to exclude shredders, while the others were not confined. Decay rates of confined leaves were not different among lakes, yet were lower than non-confined leaves in the alkaline lakes, suggesting shredders were important vectors of leaf decay in the alkaline lakes, but not in the acid lakes. Shredders comprised 65.9% of all invertebrates in Douglas Lake (pH = 8.0) and decreased in abundance (to 1.1%) with decreasing pH. Crustaceans and molluscs were few or absent in the acid lakes probably because of low pH and Ca2+ levels. Although microbial biomass on leaves appeared to be highest in acid lakes, estimates of microbial activity were significantly lower in the acid lakes, suggesting microbial metabolic inhibition at low pH.

Low pH affects the fertilization and development of Rana pipiens eggs

1981 ◽  
Vol 59 (9) ◽  
pp. 1693-1699 ◽  
Author(s):  
L. C. Schlichter
Keyword(s):  
Early Development ◽  
Sperm Motility ◽  
Rana Pipiens ◽  
Low Ph ◽  
Leopard Frog ◽  
Stages Of Development ◽  
Northern Leopard Frog ◽  
Early Stages ◽  
Effects Of Ph ◽  
Decreasing Ph

Effects of pH on fertilization and the early stages of development of the northern leopard frog, Rana pipiens, were investigated in the laboratory. Sperm motility decreased with decreasing pH below 6.5 in unbuffered solutions acidified with H2SO4 or HNO3, and below 5.5 in buffered solutions acidified with HCl. Motility was lower in the presence of HNO3 than in the presence of H2SO4. No eggs developed at pH 4.8 or below and this failure could not be attributed to low sperm motility. When eggs were inseminated in buffered solutions fertilization, activation, and cleavage decreased with decreasing pH below 6.3, falling to 50% of maximum at about pH 5.8. Fertilizing the eggs at pH 7.3, then transferring them to buffered solutions of lower pH, significantly improved the rate of survival in the first 24 h. Marked decreases in survival occurred at pH 5.8 or below, falling to 50% of maximum at about pH 5.5. By 48 h the embryos at pH 5.5 and 5.8 had stopped developing. Fertilization was more susceptible to low pH than was activation or cleavage. Provided eggs were fertilized, they continued developing at pH 6.0 to 7.5. Below pH 5.8, most fertilized eggs were activated but stopped developing before first cleavage. I concluded that waters more alkaline than pH 6.0 are optimal for fertilization and early development in R. pipiens.

The effects of pH on force and stiffness development in mouse muscles

1987 ◽  
Vol 65 (8) ◽  
pp. 1798-1801 ◽  
Author(s):  
J. M. Renaud ◽  
R. B. Stein ◽  
T. Gordon
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Force Production ◽  
Muscle Length ◽  
Low Ph ◽  
Muscle Stiffness ◽  
Average Force ◽  
Cross Bridge ◽  
Effects Of Ph ◽  
Cross Bridges

Changes in force and stiffness during contractions of mouse extensor digitorum longus and soleus muscles were measured over a range of extracellular pH from 6.4 to 7.4. Muscle stiffness was measured using small amplitude (<0.1% of muscle length), high frequency (1.5 kHz) oscillations in length. Twitch force was not significantly affected by changes in pH, but the peak force during repetitive stimulation (2, 3, and 20 pulses) was decreased significantly as the pH was reduced. Changes in muscle stiffness with pH were in the same direction, but smaller in extent. If the number of attached cross-bridges in the muscle can be determined from the measurement of small amplitude, high frequency muscle stiffness, then these findings suggest that (a) the number of cross-bridges between thick and thin filaments declines in low pH and (b) the average force per cross-bridge also declines in low pH. The decline in force per cross-bridge could arise from a reduction in the ability of cross-bridges to generate force during their state of active force production and (or) in an increased percentage of bonds in a low force, "rigor" state.

scholarly journals Efficient Heterogeneous Activation of Persulfate by Iron-Modified Biochar for Removal of Antibiotic from Aqueous Solution: A Case Study of Tetracycline Removal

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 49 ◽  
Author(s):  
Van-Truc Nguyen ◽  
Chang-Mao Hung ◽  
Thanh-Binh Nguyen ◽  
Jih-Hsing Chang ◽  
Tsing-Hai Wang ◽  
...  
Keyword(s):  
Organic Contaminants ◽  
Low Ph ◽  
Spent Coffee Grounds ◽  
Modified Biochar ◽  
Batch System ◽  
Coffee Grounds ◽  
Emerging Organic Contaminants ◽  
Effects Of Ph ◽  
Science Community

Waste reutilization is always highly desired in the environmental engineering and science community. In this study, Fe-SCG biochar was functionalized by modifying spent coffee grounds (SCG) with magnetite (Fe3+) at 700 °C and applied for the oxidative removal of tetracycline (TC) with the presence of persulfate (PS). The effects of pH, dosage of biochar and sodium persulfate and initial TC concentration on TC degradation were investigated in a batch system. Our results show that higher TC degradation efficiency was obtained at low pH, low initial TC concentration, and at high dosages of PS and biochar. The highest removal efficiency (96%) was achieved by Fe-SCG/PS under the conditions of pH = 2.0, [Fe-SCG] = 2.5 g/L, [PS] = 60 mM and [TC] = 1 mM. The proposed Fe-SCG catalyst could be a promising effective biochar for the remediation of other emerging organic contaminants.

Interaction between effects of low pH and low ion concentration on mortality during early development of medaka, Oryzias latipes

1989 ◽  
Vol 67 (9) ◽  
pp. 2158-2168 ◽  
Author(s):  
Weerawan Chulakasem ◽  
Jay A. Nelson ◽  
John J. Magnuson
Keyword(s):  
Ionic Strength ◽  
Oryzias Latipes ◽  
Calcium Content ◽  
Explanatory Models ◽  
Low Ph ◽  
Ion Concentration ◽  
Physiological Mechanisms ◽  
Effects Of Ph ◽  
Independent Effects ◽  
Patterns Of Interaction

Eggs and fry of medaka, Oryzias latipes, were incubated continuously from shortly after fertilization until 7 days after hatching using a factorial design with four water conductivities (9, 16, 28, and 49 μS/cm) and four pH levels (4.2, 4.5, 5.6, or 6.6). Results on survival suggest that only during hatching can independent effects of pH and ionic strength be statistically separated. Mortalities of encapsulated embryos and fry were determined by interactions between pH and ionic strength. Sensitivity to dilute, low pH water was greatest in freshly fertilized eggs and 1- to 4-day-old fry. Egg mortality occurred within a day after water hardening, whereas fry mortality occurred more gradually over the 3 days following hatching. Dilute, low pH water did not influence oxygen consumption or calcium content of eggs, yet impeded normal developmental increases in both calcium content and metabolic rate in fry. Results are discussed mechanistically with respect to causes of the mortality, and two explanatory models are proposed. Speculation that patterns of interaction in multivariate analyses can be indicative of physiological mechanisms also is entertained.

Effects of pH on the early development and growth and otolith microstructure of chinook salmon, Oncorhynchus tshawytscha

1985 ◽  
Vol 63 (1) ◽  
pp. 22-27 ◽  
Author(s):  
G. H. Geen ◽  
J. D. Neilson ◽  
M. Bradford
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Growth Increment ◽  
Low Ph ◽  
Acidic Water ◽  
Daily Growth ◽  
Stage Of Development ◽  
Growth Increments ◽  
Effects Of Ph ◽  
Daily Growth Increment

Chinook salmon (Oncorhynchus tshawytscha) eggs, alevins, and fry were reared in pH 4.5, 5.0. 5.5, 6.2 (control), and 7.0 water from the eyed stage of development. Survival through hatching was >90% in all instances. Alevin mortality was high at pH 4.5 and 5.0. Fry were more tolerant of low pH than alevins. Growth rates of alevins and fry held at or above pH 5.0 and 4.5, respectively, were not affected by pH, nor did exposure to acidic water retard otolith development or result in their resorption. One otolith daily growth increment was formed every 24 h in alevins and fry irrespective of pH. Widths of otolith daily growth increments decreased when fry were transferred to pH 4.5 water and increased on their return to higher pH indicating changes in growth rate. Transfer of fry from pH 6.2 to pH 5.0 or 5.5 had no effect on increment widths.

The effect of solution pH and external calcium concentration on the early growth and nodulation of several annual Medicago species

1990 ◽  
Vol 41 (5) ◽  
pp. 933 ◽  
Author(s):  
MA Ewing ◽  
AD Robson
Keyword(s):  
Calcium Concentration ◽  
Acid Soils ◽  
Early Growth ◽  
Low Ph ◽  
Solution Ph ◽  
Nodule Number ◽  
Low Calcium ◽  
Wide Range ◽  
Effects Of Ph ◽  
Annual Medics

The study tested the hypothesis that annual medic species which nodulate well in acid soils in the field (M. murex Willd. and M. polymorpha L.) will nodulate better in acid solutions with low calcium concentrations than annual medics which nodulate poorly in acid soils (M, truncatula Gaertn.). Effects of pH (5.5 and 6.5) and calcium concentration (0.2, 0.5, 1 and 2 mM) on the early growth and nodulation of three annual medic species (M. truncatula, M. polymorpha and M. murex) were investigated. Increasing pH or calcium concentration did not increase plant growth for any of the species. However, nodulation was generally depressed by low pH for all species. Increasing calcium concentration in solution increased nodulation in all species. Effects of low pH and low calcium concentration in decreasing nodule number were much greater for M. truncatula than for M. polymorpha and M. murex. At pH 5.5, M. truncatula failed to nodulate at any calcium concentration, whereas a large proportion of M. murex plants nodulated at 1 mM calcium and some M. polymorpha plants nodulated at 2 mM calcium. At pH 6.5, M. polymorpha required 1 mM calcium in solution for maximum nodule number, and M. murex only 0.5 mM calcium, whereas nodule number for M. truncatula increased up to 2 mM calcium, the highest concentration used. The results provide the basis for a simple screening system to distinguish differences among annual medics in nodulation tolerance to acidity. The maintenance of ranking among species with respect to nodulation over a wide range of stresses induced by combinations of low pH and calcium concentration suggest that screening using a single stress combining these two components would be adequate. Nodulation differences between species can be simply and effectively assessed using a scoring system combining number size and location of nodules.

scholarly journals Binding of active and inactive forms of lipoprotein lipase to heparin. Effects of pH

1985 ◽  
Vol 226 (2) ◽  
pp. 409-413 ◽  
Author(s):  
G Bengtsson-Olivecrona ◽  
T Olivecrona
Keyword(s):  
Catalytic Activity ◽  
Lipoprotein Lipase ◽  
Low Ph ◽  
Cell Surface Receptor ◽  
Physiological Conditions ◽  
Enzyme Binding ◽  
Cell Compartments ◽  
Effects Of Ph ◽  
Surface Receptor ◽  
Active Lipase

Lipoprotein lipase has been shown to bind to, be internalized by, and perhaps be transferred through, a variety of cells. These processes may involve a heparin-like cell-surface receptor and passage through acidified cell compartments. We have therefore studied effects of low pH on the binding of the lipase to heparin and on its catalytic activity. The rate of inactivation of the lipase in solution was found to increase as the pH was lowered. Addition of heparin stabilized the enzyme. Binding of active lipoprotein lipase to heparin-Sepharose could be demonstrated at pH down to 6.5. At pH below 6, binding could not be studied directly because the lipase was too unstable in solution. Lipase bound to heparin-Sepharose could, however, be exposed to pH 4.5 at 10 degrees C with little loss of activity. Binding to heparin-Sepharose also stabilized under physiological conditions (37 degrees C, 0.15 M-NaCl, pH 5.5-7.4). Catalytically inactive lipoprotein lipase retained the ability to bind to heparin-Sepharose. Higher concentrations of salt were needed to displace both active and inactive lipase from heparin-Sepharose at lower pH, indicating that the affinity increased as pH was lowered. The inactive lipase was, however, displaced by lower concentrations of salt than was active lipase.

Effect of pH on the Luminescent Properties of the Green Fluorescent Ink-Jet Ink

2011 ◽  
Vol 380 ◽  
pp. 107-111 ◽  
Author(s):  
Shao Hong Gao ◽  
Xian Fu Wei ◽  
Bei Qing Huang ◽  
Chun Yan Lu
Keyword(s):  
Quantum Yield ◽  
Ph Value ◽  
Luminescent Properties ◽  
Low Ph ◽  
Luminous Intensity ◽  
Ink Jet ◽  
Effects Of Ph ◽  
Deep Ultraviolet ◽  
Fluorescent Quantum Yield ◽  
Green Fluorescent

pH value of fluorescent ink-jet ink has an obvious influence on fluorescent powder, high or low pH value could cause some problems, such as fluorescence quenches, fluorescent quantum yield decreased, and so on. And these factors make against fluorescent ink-jet ink luminous properties reach the best result. This article is to design fluorescent ink-jet ink formula when it is exposured to deep Ultraviolet light to display green, and a series of ink samples were prepared. pH regulator was used to regulate pH value of green fluorescent ink-jet ink system. This paper discusses the effects of pH value on luminous intensity, fluorescent quantum yield. The results indicated that triethanolamine can regulate pH value of fluorescent ink-jet ink, when pH value increases from 8.70 to 11.20, luminous intensity, fluorescent quantum yield have a decrease tendency.

Use of used vs. fresh cheese brines and the effect of pH and salt concentration on the survival of Listeria monocytogenes

2014 ◽  
Vol 81 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Bjørn C T Schirmer ◽  
Even Heir ◽  
Bjørn-Arne Lindstedt ◽  
Trond Møretrø ◽  
Solveig Langsrud
Keyword(s):  
Listeria Monocytogenes ◽  
Tandem Repeats ◽  
Variable Number ◽  
Low Ph ◽  
Small Scale ◽  
Death Rates ◽  
Effects Of Ph ◽  
Fresh Cheese ◽  
Pathogen Populations ◽  
Variable Number Tandem Repeats

The aim of the study was to investigate how the use of fresh cheese brines compared with used brines and various combinations of pH and NaCl concentrations affected the survival of Listeria monocytogenes. Cheese brines from five Norwegian small scale cheese producers were analysed and showed great variations in pH (4·54–6·01) and NaCl concentrations (14·1–26·9 %). The survival of five strains of List. monocytogenes (two clinical isolates, two food isolates and one animal isolate) in four different cheese brines (three used and one fresh) was investigated. Results showed significant differences in survival both depending on the strains and the brines. Strains of human outbreak listeriosis cases showed greater ability to survive in the brines compared with food isolates and a List. monocytogenes reference strain (1–2 log10 difference after 200 d). All strains showed highest survival in the freshly prepared brine compared with the used brines. Molecular typing by multiple locus variable number tandem repeats analysis (MLVA) showed that there were no detectable alterations in the examined variable number tandem repeats of the genome in five strains after 200 d storage in any of the salt brines. Combined effects of pH (4·5, 5·25 and 6·0) and NaCl (15, 20 and 25 %) in fresh, filter sterilised brines on the survival of List. monocytogenes were examined and results showed that pathogen populations decreased over time in all brines. Death rates at any given NaCl concentration were highest at low pH (4·5) and death rates at any given pH were highest at low NaCl concentrations (15 %). In conclusion, the use of used brines reduced the survival of List. monocytogenes and a combination of low pH (4·5) and low salt concentrations (15 %) decreased the risk of List. monocytogenes survival compared with higher pH (5·25 or 6·0) and higher NaCl concentrations (20 or 25 %).

scholarly journals Identification of the Gene Encoding the Alternative Sigma Factor ςB from Listeria monocytogenesand Its Role in Osmotolerance

1998 ◽  
Vol 180 (17) ◽  
pp. 4547-4554 ◽  
Author(s):  
Lynne A. Becker ◽  
Mehmet Sevket Çetin ◽  
Robert W. Hutkins ◽  
Andrew K. Benson
Keyword(s):  
Sigma Factor ◽  
Low Temperatures ◽  
Low Ph ◽  
Alternative Sigma Factor ◽  
Null Mutation ◽  
Gene Encoding ◽  
Related Bacterium ◽  
Physical Organization ◽  
Physical And Chemical ◽  
Insight Into

ABSTRACT Listeria monocytogenes is well known for its robust physiology, which permits growth at low temperatures under conditions of high osmolarity and low pH. Although studies have provided insight into the mechanisms used by L. monocytogenes to allay the physiological consequences of these adverse environments, little is known about how these responses are coordinated. In the studies presented here, we have cloned the sigB gene and severalrsb genes from L. monocytogenes, encoding homologs of the alternative sigma factor ςB and the RsbUVWX proteins, which govern transcription of a general stress regulon in the related bacterium Bacillus subtilis. TheL. monocytogenes and B. subtilis sigB andrsb genes are similar in sequence and physical organization; however, we observed that the activity of ςB in L. monocytogenes was uniquely responsive to osmotic upshifting, temperature downshifting, and the presence of EDTA in the growth medium. The magnitude of the response was greatest after an osmotic upshift, suggesting a role for ςB in coordinating osmotic responses in L. monocytogenes. A null mutation in the sigB gene led to substantial defects in the ability of L. monocytogenesto use betaine and carnitine as osmoprotectants. Subsequent measurements of betaine transport confirmed that the absence of ςB reduced the ability of the cells to accumulate betaine. Thus, ςB coordinates responses to a variety of physical and chemical signals, and its function facilitates the growth of L. monocytogenes under conditions of high osmotic strength.

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