Concentrations and Kinetics of Phosphorus Fractions Along the Trophic Gradient of Lake Memphremagog

1979 ◽  
Vol 36 (8) ◽  
pp. 970-979 ◽  
Author(s):  
Robert Henry Peters
Keyword(s):  
Molecular Weight ◽  
Total Phosphorus ◽  
Gel Filtration ◽  
Soluble Reactive Phosphorus ◽  
Small Molecular Weight ◽  
P Deficiency ◽  
Large Molecular Weight ◽  
Soluble P ◽  
Phosphorus Production ◽  
Total P

Published relationships between chlorophyll and total phosphorus concentrations show that the amount of chlorophyll developed per unit of total P increases as total P increases. If the availability of phosphorus changes with lake trophy, this should be reflected in the proportion of total P found in different analytical fractions. From June 1975 to September 1976, the concentrations of total phosphorus, soluble phosphorus, orthophosphate, large molecular weight phosphorus (> 5000 mol wt) and small molecular weight phosphorus (< 400 mol wt) were measured at six sites along the phosphorus-production gradient of Lake Memphremagog; 32P-PO4 was used to follow short-term exchanges between available orthophosphate and other fractions. Total P declined threefold among sites but the proportion of different fractions remained relatively constant which suggests that any disproportionate loss from one compartment is made good by exchanges with the others. On average, soluble P formed\of total P, soluble reactive phosphorus formed 14%, and PO4 8%; gel filtration showed that ~40% of soluble P was associated with large molecular weight phosphorus and ~40% with small molecular weight phosphorus. Within this basic similarity, was a trend to decreased PO4 concentrations and increased concentrations of soluble P and soluble unreactive phosphorus at more oligotrophic sites. Tracer experiments showed that all fractions exchanged some P with 32P-PO4, although soluble fractions, especially large molecular weight phosphorus, interacted more slowly with orthophosphate than did particulate P. Faster orthophosphate turnover suggested greater P deficiency in more oligotrophic sites. This deficiency may promote the formation of a refractory soluble P which may explain a part of the reduced ratio of chlorophyll to phosphorus when total P is reduced. Key words: orthophosphate, phosphorus, turnover, availability, lakes, gel fitration, soluble organic P

A Comparison of Different Phosphorus Fractions as Predictors of Particulate Pigment Levels in Lake Memphremagog and its Tributaries

1982 ◽  
Vol 39 (5) ◽  
pp. 785-790 ◽  
Author(s):  
Robert Henry Peters ◽  
Martin Bergmann
Keyword(s):  
Molecular Weight ◽  
Soluble Reactive Phosphorus ◽  
Particulate Material ◽  
Phosphorus Fractions ◽  
Particulate Phosphorus ◽  
Small Molecular Weight ◽  
Large Molecular Weight ◽  
Reactive Phosphorus ◽  
Lake Waters ◽  
Total P

The amounts of colored particulate material (measured by reflectance) in surface waters of Lake Memphremagog and its tributaries were regressed against concentrations of total phosphorus and several of its component fractions: soluble phosphorus, particulate phosphorus, soluble reactive phosphorus, orthophosphate, large molecular weight phosphorus (> 5000 mol wt) and small molecular weight phosphorus (< 400 mol wt). The correlations were examined to see if one of these fractions was a better predictor of seston concentration, and presumably of other biologically related lake properties, than total P, and to determine if riverine samples differed from lake waters in the relation between concentrations of P and suspended particulates. Total P correlated with colored particulates in both lotic and lentic samples as well as or better than any other fraction. Although river samples showed greater variation than lake samples, the regression lines describing the relations were similar in both lakes and rivers.Key words: phosphorus fractions, lakes, rivers, empirical models, particulate concentration, seston

Concentrations and Kinetics of Phosphorus Fractions in Water from Streams Entering Lake Memphremagog

1978 ◽  
Vol 35 (3) ◽  
pp. 315-328 ◽  
Author(s):  
Robert Henry Peters
Keyword(s):  
Molecular Weight ◽  
River Water ◽  
Weight Fraction ◽  
Water Soluble ◽  
Organic P ◽  
P Fractions ◽  
P Concentration ◽  
Large Molecular Weight ◽  
Soluble P ◽  
Total P

This study examines the possibility that the proportions of different P fractions may vary among rivers, and hence, that the P supplied to lakes may differ in its availability for algae regardless of any similarities in the total P concentration of river waters. Surface water from eight streams and groundwater was collected at roughly monthly intervals from June 1975 to September 1976 and analyzed to determine the concentrations of P fractions and the interrelations between these forms and orthophosphate. Despite differences in total P concentration, (18–64 μg/L) the proportions of P in different fractions were relatively constant seasonally and geographically. Soluble P formed about one third and PO4 < 10% of the total P. These values were not greatly affected by urban drainage but both were increased in small headwater streams during periods of low water. Soluble P was divided into two roughly equal fractions by gel filtration: a large molecular weight fraction (> 5000 mol wt) which eluted at void volume and a small molecular weight fraction (< 400 mol wt) which eluted with 32P-PO4. This latter fraction also included some small organic phosphates. Soluble reactive phosphate consistently overestimated PO4. The exchange of P between PO4 and suspended material was slow in winter and more rapid in summer, although only rivers draining lakes, embayments, or bogs reached the very rapid values reported from lakes. As in lakes, soluble organic P entered into the short-term P dynamics of streams as indicated by the labeling of large molecular weight P during equilibration of river water with radioactive phosphate. This exchange shows that at least a portion of the soluble organic and particulate P is available to the plankton once the river water enters a lake. The uncertainty as to the size of this portion leads to uncertainty in predicting the impact of P loading on lakes. Key words: nutrient budget, P loading, orthophosphate, soluble organic P, drainage basins

Bioactive parathyroid hormone in canine progressive renal insufficiency

1984 ◽  
Vol 247 (4) ◽  
pp. E442-E448
Author(s):  
D. Grunbaum ◽  
M. Wexler ◽  
M. Antos ◽  
M. Gascon-Barre ◽  
D. Goltzman
Keyword(s):  
Molecular Weight ◽  
Renal Failure ◽  
Parathyroid Hormone ◽  
Renal Insufficiency ◽  
Final Stage ◽  
Gel Filtration ◽  
Small Molecular Weight ◽  
Dihydroxyvitamin D ◽  
Severe Renal Disease ◽  
Circulating Levels

Bioactive parathyroid hormone and hormonal actions were monitored as hyperparathyroidism evolved in a model of progressive canine renal failure. Circulating levels of bioactive and immunoreactive parathyroid hormone rose as renal insufficiency worsened, but elevations, especially in bioactivity, were most marked in the final stage of uremia. By gel filtration analysis, the major circulating bioactive moiety was similar to the major glandular form of parathyroid hormone, although a smaller-molecular-weight entity was seen in the final stage of renal failure. Renal phosphate threshold fell, urinary hydroxyproline corrected for glomerular filtration rose, and plasma 1,25-dihydroxyvitamin D fell but remained detectable, as renal function deteriorated. The results demonstrate a progressive rise in bioactive parathyroid hormone, show the appearance of a small-molecular-weight bioactive entity in severe renal disease, and correlate effects of the rising bioactive parathyroid hormone with changes in renal phosphate handling and with skeletal resorption.

Fate of receptor-bound human chorionic gonadotrophin in pseudopregnant rat ovaries perfused in vitro

1985 ◽  
Vol 109 (1) ◽  
pp. 115-121
Author(s):  
Hannu Rajaniemi ◽  
Jan Sogn ◽  
Paul Holmes ◽  
Björn Källfelt ◽  
Per Olof Janson
Keyword(s):  
Molecular Weight ◽  
Histological Examination ◽  
Gel Filtration ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Cell Periphery ◽  
Small Molecular Weight ◽  
Immunohistochemical Studies

Abstract. Pseudopregnant rats were injected with [125I] hCG, anaesthesized 1 h later and after cannulation of the aorta the ovaries were isolated and perfused with Gey & Gey buffer containing 0.2% BSA. The release of radioactivity was monitored for 2 h and analyzed by gel filtration. Five to ten per cent of the radioactivity was released within 2 h and represented small molecular weight peptides and iodotyrosine and [125I]hCG. Analysis of the ovarian radioactivity prior to and after perfusion revealed that virtually all hCG was receptor-bound. Loading the medium with unlabelled hCG displaced [125I]hCG from the receptor but did not enhance its degradation. Histological examination showed that the ovarian tissues were still intact after the 2 h perfusion. Immunohistochemical studies revealed a localization of the hCG at the cell periphery both prior to and after perfusion. These results provide evidence showing that the rate of internalization of receptor-hCG complexes in rat luteal cells is slow in vivo.

scholarly journals PROPERTIES OF COMPOSITE MATERIALS BASED ON MIXTURES OF EPOXY POLYMERS AND OLIGOSULFONES. PART 4. ADHESION PROPERTIES

2020 ◽  
pp. 84-93
Author(s):  
Yuriy Kochergin ◽  
Tatyana Grigorenko ◽  
V. Zolotareva
Keyword(s):  
Molecular Weight ◽  
Epoxy Oligomer ◽  
Carboxyl Groups ◽  
Maximum Effect ◽  
Optimal Range ◽  
Small Molecular Weight ◽  
Adhesion Properties ◽  
Molecular Weights ◽  
Epoxy Polymers ◽  
Large Molecular Weight

The influence of oligosulfons with terminal carboxyl and phenolic groups and a molecular weight from 1200 to 44500 on the adhesion properties of epoxy polymers during the shift and separation of adhesive compounds is studied. It is shown that modification leads to the formation of systems characterized by improved adhesion properties, especially at elevated test temperatures. It is established that there is an optimal range of concentrations and molecular weights of oligosulfons (approximately from 2000 to 20000), which provides the maximum effect of modification. It is assumed that the oligosulfon`s particles formed in the epoxy matrix with a small molecular weight have dimensions and volume that are insufficient to be an effective barrier to the propagation of a possible crack in the polymer. At the same time, an oligosulfon with a large molecular weight is able to include a certain part of the epoxy resin in its volume. This leads to a relative decrease in the composition of the share of the epoxy component, which largely determines the adhesion to the material to be bonded. It is shown that the magnitude of the modification effect practically does not depend on the nature of the end groups. The maximum set of properties is realized for oligosulfones with terminal carboxyl groups and a molecular weight in the range from 2500 to 4700, when the concentration of 3 – 10 mass parts on 100 mass parts epoxy oligomer. For oligosulfone with terminal carboxyl groups and a molecular weight of 4700 at a concentration of 10 mass parts manages to increase adhesive strength at a shear of 1.47 and 3.58 times and tensile strength of 1.39 and 5.08 times, respectively, at test temperatures of 293 and 423 K. The research results allow to recommend epoxy-oligosulfone mix to design of structural adhesives, operable in a wide temperature range.

Fibrin and Fibrinogen Proteolysis Products: Comparison between Gel Filtration and SDS Polyacrylamide Electrophoresis Analysis

1977 ◽  
Vol 38 (02) ◽  
pp. 0524-0535 ◽  
Author(s):  
Norma Alkjaersig ◽  
Andrew Davies ◽  
Anthony Fletcher
Keyword(s):  
Molecular Weight ◽  
Analytical Methods ◽  
Gel Filtration ◽  
Molecular Size ◽  
The Other ◽  
Reaction Products ◽  
Human Fibrinogen ◽  
Polyacrylamide Electrophoresis ◽  
Large Molecular Weight ◽  
Stabilized Fibrin

SummaryThe proteolysis of purified human fibrinogen, stabilized and non-stabilized fibrin by plasmin were investigated by gel filtration analysis and SDS polyacrylamide electrophoresis of the reaction products. Plasmin proteolysis of fibrinogen followed the sequential steps previously reported and the two analytical methods yielded concordant results. Large molecular weight proteolysis products, of substantially greater molecular weight than native fibrinogen, were identified by gel filtration analysis following dissolution of stabilized and non-stabilized fibrin clots; with further incubation with plasmin, these proteolysis products gradually diminished in size. On the other hand, SDS polyacrylamide electrophoresis of these fibrin digests demonstrated that while non-stabilized fibrin yielded breakdown products similar in size to those obtained after proteolysis of fibrinogen, stabilized fibrin digests showed moieties of greater molecular size estimated to be of molecular weight 400,000 to 800,000. The final breakdown products of stabilized fibrin differed from those of fibrinogen and nonstabilized fibrin in that fragment D was present in the “double D” cross-linked form.

Big ANF: large-molecular-weight ANF in plasma. I. Gel filtration and affinity chromatography studies

1991 ◽  
Vol 261 (4) ◽  
pp. E516-E524
Author(s):  
N. Wilson ◽  
V. Yakoleff ◽  
R. Keeler
Keyword(s):  
Molecular Weight ◽  
Affinity Chromatography ◽  
Gel Electrophoresis ◽  
Atrial Natriuretic Factor ◽  
Molecular Form ◽  
Gel Filtration ◽  
Gel Chromatography ◽  
Natriuretic Factor ◽  
Large Molecular Weight ◽  
High Concentrations

A large molecular form of immunoreactive atrial natriuretic factor (irANF) was demonstrated in plasma of rabbit and rat on the basis of gel filtration experiments. This big ANF was not retained by octadecylsilane cartridges and cross-reacted with four anti-ANF antisera of different specificities. Gel filtration in acid, but not in 8 M urea, resulted in material with elution characteristics of irANF. Affinity chromatography and gel electrophoresis of big ANF suggested that the material was similar to albumin. However, high concentrations of big ANF were found in analbuminemic rats, with characteristics similar to those seen in rabbit and normal rats (affinity and gel chromatography and gel electrophoresis). We thus conclude that big ANF represents a bound form of ANF in circulation and that the carrier is similar to but not identical with albumin.

THE EFFECT OF DIFFERENT EXTRACTION PROCEDURES ON TWO DIFFERENT MOLECULAR WEIGHT SPECIES OF SERUM NSILA AND ON THE CARRIER PROTEIN OF SMALL MOLECULAR WEIGHT NSILA (NSILA-S)

1979 ◽  
Vol 90 (4) ◽  
pp. 637-647 ◽  
Author(s):  
U. Kaufmann ◽  
J. Zapf ◽  
E. R. Froesch
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Binding Protein ◽  
Extraction Procedure ◽  
Gel Filtration ◽  
Adsorption Chromatography ◽  
Carrier Protein ◽  
List Type ◽  
Small Molecular Weight ◽  
Binding Characteristics

ABSTRACT The influence of Dowex-50 adsorption chromatography on the recovery of two different forms of serum NSILA, large and small mol. wt. NSILA, and on the recovery of the binding protein of the small mol. wt. form was studied and compared with another extraction procedure, gel filtration on Sephadex G-50 in 1 m acetic acid. Partially purified NSILA-S is adsorbed to Dowex-50 at pH 6.8. It can be eluted with 20 mm NH4OH and appears unchanged with regard to its biological activity and molecular weight. Adsorption of 125I-labelled NSILA-S to Dowex-50 does not change its binding characteristics to serum. When serum is chromatographed on Sephadex G-50 in 1 m acetic acid, NSILA is obtained in a large and in a small molecular weight form (NSILA-S). After recombination of the small molecular weight NSILA fraction with the "stripped" serum fraction, which contains large mol. wt. NSILA and a specific carrier protein for NSILA-S, re-chromatography of this mixture on Sephadex G-50 at neutral pH yields NSILA mostly in the void volume. It adsorbs to Dowex-50. After elution from Dowex, acidic gel filtration on Sephadex G-50 results in an elution pattern which is completely different from that of NSILA-S. Adsorption of serum to Dowex-50 results in a dramatic decrease of the NSILA-S binding activity. It is concluded that Dowex-50 adsorption chromatography of serum inactivates most of the serum NSILA-S binding protein leads to the loss of acid dissociable small mol. wt. NSILA (NSILA-S). Therefore, Dowex-50 adsorption chromatography is not suitable for the subsequent determination or further purification of NSILA-S from whole serum.

Sign in / Sign up

Export Citation Format

Share Document