Apparent Aggregation Research Articles

Investigation of the micellar properties of the tocopheryl polyethylene glycol succinate surfactants TPGS 400 and TPGS 1000 by steady state fluorometry

This study has investigated the micellar properties of the d- α-tocopheryl polyethylene glycol succinate esters 400 (TPGS 400) and 1000 (TPGS 1000) in terms of critical micellar concentration (CMC), apparent aggregation number ( N agg ), microviscosity and micropolarity using steady state fluorescence techniques and fluorescent probes. In addition it has compared these properties against those of a Triton-type surfactant such as Triton X-100. The CMC values for TPGS 400, TPGS 1000 and Triton X-100 were 1.51 mM, 0.02 mM and 0.19 mM, respectively. The N agg values for TPGS 1000 and Triton X-100 were, respectively, 10 and 63. Due to the cloudiness of its aqueous solutions, no attempt was made to evaluate the microviscosity and to obtain the N agg for TPGS 400. Microviscosity at the probe site for all three surfactants was high and rather similar in spite of differences among their CMC values. The ability of TPGS 400 and TPGS 1000 to provide an environment for the fluorescence quenching of micelle-solubilized pyrene appears to be associated with their hydrophobic aromatic domains. To our knowledge the present study is the first attempt at systematically studying the micellar properties of the two most widely used TPGS compounds and of comparing these properties against each other and against those of an established nonionic surfactant.

Melanophores in the stripes of adult zebrafish do not have the nature to gather, but disperse when they have the space to move

Animal skin pattern is one of the good model systems used to study the mechanism of pattern formation. Molecular genetic studies with zebrafish have shown that pigment cells play a major role in the mechanism of stripe formation. Among the variety of cellular events that may be involved in the mechanism, aggregation of melanophores has been suggested as an important factor for pattern formation. However, only a few experimental studies detected the migration ability of melanophores in vivo. Here, we tried to determine whether melanophores really have the ability to aggregate in the skin of zebrafish. Melanophores in the adult stripes are packed densely and they rarely move. However, when the neighboring pigment cells are killed, they move and regenerate the stripe pattern, suggesting that melanophores retain the migration ability. To analyze the migration, we ablated a part of the melanophores by laser to give free space to the remaining cells; we then traced the migration. Contrary to our expectation, we found that melanophores repulsed one another and dispersed from the aggregated condition in the absence of xanthophores. Apparent aggregation may be forced by the stronger repulsive effect against the xanthophores, which excludes melanophores from the yellow stripe region.

The chemical neuroanatomy of breathing

The chemical neuroanatomy of breathing must ultimately encompass all the various neuronal elements physiologically identified in brainstem respiratory circuits and their apparent aggregation into "compartments" within the medulla and pons. These functionally defined respiratory compartments in the brainstem provide the major source of input to cranial motoneurons controlling the airways, and to spinal motoneurons activating inspiratory and expiratory pump muscles. This review provides an overview of the neuroanatomy of the major compartments comprising brainstem respiratory circuits, and a synopsis of the transmitters used by their constituent respiratory neurons.

Understanding the toad code: Behavioural responses of cane toad (Chaunus marinus) larvae and metamorphs to chemical cues

Abstract Larvae of many anuran taxa display strong behavioural responses to chemical cues, including alarm signals from injured conspecific tadpoles. We exposed tadpoles and metamorphs from an Australian population of the invasive cane toad (Chaunus[Bufo] marinus) to a range of chemical stimuli and quantified their responses both in the laboratory and in the field. Filtered fluids containing scent cues from crushed conspecifics elicited strong avoidance from tadpoles, whereas other cues (e.g. scent of food, of native‐range fish or urodele predators, and thermal stimuli) did not. Apparent aggregation of tadpoles in response to scent cues proved to be an artifact of tank design, and was an indirect consequence of avoidance of those cues. Field trials confirmed that free‐ranging toad tadpoles and metamorphs avoided chemical cues from crushed conspecifics, suggesting that the chemicals inducing this response might provide an opportunity to develop targeted control methods for this invasive species.

Light Scattering and Luminescence Studies on Self-Aggregation Behavior of Amphiphilic Copolymer Micelles

The self-aggregation behavior of three amphiphilic graft copolymers, oligo(9,9-dihexyl)fluorence-graft-poly(ethylene oxide) (OHF-g-PEO), with different architectures was studied by dynamic and static light scattering (DLS and SLS) in combination with fluorescence spectroscopy and transmission electron microscopy (TEM). The formation of self-assembled polymeric micelles was confirmed by SLS and TEM. DLS and SLS analyses showed that the architecture of graft copolymers has a dramatic effect on critical aggregation concentration (CAC), micelle size distribution, apparent aggregation number (Nagg app), and apparent molecular weight of polymer aggregates (Mw,agg app). An architecture-dependent excimer emission, resulting from the pi-pi stacking of the oligofluorene backbones, was also observed from the photoluminescence spectra of the micelle aqueous solutions, which indicated a strong intermolecular interaction among the polymeric molecules. The excimer emission was further investigated by time-resolved fluorescence spectroscopy.

Nonisothermal kinetic analysis of the effect of protein concentration on BSA aggregation at high concentration by DSC

The effect of protein concentration on bovine serum albumin (BSA) aggregation kinetics at high concentration was studied by differential scanning calorimetry (DSC). The nonisothermal kinetic analysis of this process was carried out using a composite procedure involving the iso-conversional method and the master plots method. The observed aggregation process was characterized by denaturation temperature ( T d max ), apparent activation energy ( E), the apparent order of reaction ( n), and pre-exponential factor ( A) which all increased with the increase of BSA concentration. The results suggested that the apparent aggregation reaction of BSA approximately conformed to the simple order reaction model. The higher BSA concentration, the higher the apparent order of reaction and the more close to 2 was. The difference intrinsic fluorescence of BSA between before and after the thermal denaturation and aggregation provided the evidences of conformation changes of BSA and the substantial impact of BSA concentration on aggregation. This study showed the combination of iso-conversional method and the master plots method could be used to model the aggregation mechanism of the protein.

Pulmonary surfactant adsorption is increased by hyaluronan or polyethylene glycol

In acute lung injuries, inactivating agents may interfere with transfer (adsorption) of pulmonary surfactants to the interface between air and the aqueous layer that coats the interior of alveoli. Some ionic and nonionic polymers reduce surfactant inactivation in vitro and in vivo. In this study, we tested directly whether an ionic polymer, hyaluronan, or a nonionic polymer, polyethylene glycol, enhanced adsorption of a surfactant used clinically. We used three different methods of measuring adsorption in vitro: a modified pulsating bubble surfactometer; a King/Clements device; and a spreading trough. In addition we measured the effects of both polymers on surfactant turbidity, using this assay as a nonspecific index of aggregation. We found that both hyaluronan and polyethylene glycol significantly increased the rate and degree of surfactant material adsorbed to the surface in all three assays. Hyaluronan was effective in lower concentrations (20-fold) than polyethylene glycol and, unlike polyethylene glycol, hyaluronan did not increase apparent aggregation of surfactant. Surfactant adsorption in the presence of serum was also enhanced by both polymers regardless of whether hyaluronan or polyethylene glycol was included with serum in the subphase or added to the surfactant applied to the surface. Therefore, endogenous polymers in the alveolar subphase, or exogenous polymers added to surfactant used as therapy, may both be important for reducing inactivation of surfactant that occurs with various lung injuries.

Cdk5 Regulates STAT3 Activation and Cell Proliferation in Medullary Thyroid Carcinoma Cells

The biological behaviors of thyroid cancer are varied, and the pathological mechanisms remain unclear. Some reports indicated an apparent aggregation of amyloid accompanying medullary thyroid carcinoma (MTC). Amyloid aggregation in neurodegeneration leads to hyperactivation of Cdk5 and subsequent neuronal death. Based on the connection with amyloid, the role of Cdk5 in MTC is worthy of investigation. Initially, the expression of Cdk5 and its activator, p35, in MTC cell lines was identified. Cdk5 inhibition by specific inhibitors or short interfering RNA decreased the proliferation of MTC cell lines, which reveals the importance of Cdk5 in MTC cell growth. Although p35 cleavage has been considered as an important element in neurodegeneration, it seems that p35 cleavage was not a major cause in Cdk5 activity-dependent MTC cell proliferation because neither Cdk5 activity nor cell growth was affected by the inhibition of p35 cleavage. Clearance of amyloid by antibody neutralization indicated that MTC cell proliferation was supported by calcitonin-derived extracellular amyloid and subsequent Her2 and Cdk5 activation. Significantly, the STAT3 pathway was involved in Cdk5-dependent proliferation of MTC cells through Ser-727 phosphorylation. In addition, Cdk5 inhibition reduced nuclear distributions of both the Cdk5-p35 complex and phospho-STAT3 in MTC cells. Finally, Cdk5 inhibition retarded tumor formation in vivo accompanying the reduction of phospho-STAT3. Our findings suggest the first demonstration of a novel and specific role for Cdk5 kinase in supporting the proliferation of the medullary thyroid carcinoma cells and could shed light on a new field for diagnosis and therapy of thyroid cancer.

Supramolecular Assembled Nanostructure Containing Cubic Silsesquioxane in Aqueous Solution

Micellization and aggregation behavior of amphiphilic cubic silsesquioxane-poly(ethylene oxide) (CSSQ-PEO) in aqueous solution was studied by Dynamic and Static Light Scattering (DLS and SLS), and Transmission Electron Microscopy (TEM). The effects of CSSQ-PEO concentration and temperature on particle size were also investigated. Above the critical aggregation concentration (CAC), a combination of unassociated single micelle and micellar aggregates is observed up to a certain level of CSSQ-PEO concentration as determined by DLS and TEM studies. The size of unassociated single micelles are found to be independent of CSSQ-PEO concentration while that of the micellar aggregates become larger at higher concentration due to the aggregation growth. Both studies revealed that a small CSSQ core is surrounded by PEO corona and found self-assembled nanostructure of CSSQ-PEO in aqueous solution. The molecular weight of micellar aggregates (Mw,agg), radius of gyration (Rg), and apparent aggregation number (Nagg) were evaluated by SLS measurement. The decrease in the particle size (described by hydrodynamic diameter: Dh) upon increasing temperature was observed because of the diminishing hydrophilicity of PEO. Surprisingly, Rg is also decreased at higher temperature assuming the dissociation of micellar aggregates by repulsive forces due to the crowding effect. The encapsulation property of CSSQ-PEO to model drug has also been studied. Our preliminary results from DLS and TEM studies showed the formation of CSSQ-PEO nanospheres containing drug in aqueous solution. The size of the drug loaded CSSQ-PEO nanospheres are found to be larger (250-300 nm) than that of the core-corona CSSQ-PEO micellar aggregates (approximatly 180 nm) in dilute aqueous solution.

Folding and Assembly of Hemoglobin Monitored by Electrospray Mass Spectrometry Using an On-line Dialysis System

The native structure of hemoglobin (Hb) comprises two alpha- and two beta-subunits, each of which carries a heme group. There appear to be no previous studies that report the in vitro folding and assembly of Hb from highly unfolded alpha- and beta-globin in a "one-pot" reaction. One difficulty that has to be overcome for studies of this kind is the tendency of Hb to aggregate during refolding. This work demonstrates that denaturation of Hb in 40% acetonitrile at pH 10.0 is reversible. A dialysis-mediated solvent change to a purely aqueous environment of pH 8.0 results in Hb refolding without any apparent aggregation. Fluorescence, Soret absorption, circular dichroism, and ESI mass spectra of the protein recorded before unfolding and after refolding are almost identical. By employing an externally pressurized dialysis cell that is coupled on-line to an ESI mass spectrometer, changes in heme binding behavior, protein conformation, and quaternary structure can be monitored as a function of time. The process occurs in a stepwise sequential manner, leading from monomeric alpha- and beta-globin to heterodimeric species, which then assemble into tetramers. Overall, this mechanism is consistent with previous studies employing the mixing of folded alpha- and beta-globin. However, some unexpected features are observed, e.g., a heme-deficient beta-globin dimer that represents an off-pathway intermediate. Monomeric beta-globin is capable of binding heme before forming a complex with an alpha-subunit. This observation suggests that holo-alpha-apo-beta globin does not represent an obligatory intermediate during Hb assembly, as had been proposed previously. The on-line dialysis/ESI-MS approach developed for this work represents a widely applicable tool for studying the folding and self-assembly of noncovalent biological complexes.

Effect of the degree of deacetylation and the substitution of carboxymethyl chitosan on its aggregation behavior

AbstractThe aggregation behavior of carboxymethyl chitosan (CM‐chitosan) with various degrees of deacetylation (DD) and substitution (DS) was characterized with viscometry, gel permeation chromatography (GPC), and GPC coupled with laser light scattering (GPC‐LLS). The results indicate that CM‐chitosan has a strong tendency to form aggregates in aqueous solution and the aggregation behavior depends on DD and DS values. The apparent aggregation number (Nap), the gyration radius (Rg), and the weight fraction of the aggregates (Fa) reached maximum at a DD value of 50%, then decreased, with the DD value deviating from 50%. A higher DS value helped to form aggregates; when the DS value increased from 0.65 to above 1.0, Nap and Rg increased sharply. The dependence of the refractive index increment (dn/dc) on the DD and DS values was related to variation of the charge density and the hydrophobic interaction along the molecular chains. The conformations of CM‐chitosan aggregates were studied by the LLS method. The aggregates showed a spherical shape, and the chain stiffness increased with introduction of the acetyl groups. The DS value had no clear influence on the chain conformation that was observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 296–305, 2005

Effect of Hydrophobically Modified Polymer on Salt-Induced Structural Transition in Microemulsions

The phase boundaries of the middle-phase microemulsion for NaCl/SDS/H2O/1-heptane/1-pentanol systems in the absence of polymer and in the presence of unmodified poly(acrylamide) (PAM) and hydrophobically modified poly(acrylamide) (HMPAM) have been determined at varying salt concentrations. These three middle-phase microemulsions (with HMPAM, with PAM, and without polymer) were studied using interfacial tension measurement, steady-state fluorescence, and time-resolved fluorescence quenching. Compared to the polymer-free system and the system with PAM, the addition of HMPAM significantly enlarges the range of the salt concentrations for the formation of the middle-phase microemulison and causes both the excess oil and aqueous phases to increase in volume at the expense of the middle-phase microemulsion. For the middle-phase microemulsion with HMPAM, the interfacial tensions of the microemulsion phase with the excess oil phase and with the excess aqueous phase are all ultralow and exhibit higher values than those with PAM and without polymer. At the same salt concentration, the apparent surfactant aggregation number in the middle-phase microemulsion with HMPAM has the smallest value among these three systems. All results indicate that the strong interaction of surfactant with hydrophobically modified polymer has a large effect on the formation and properties of the middle-phase microemulsion.

Aggregation behavior of 3,6‐O‐carboxymethylated chitin in aqueous solutions

AbstractThe aggregation behavior of 3,6‐O‐carboxymethylated chitin (3,6‐O‐CM‐chitin) in aqueous solutions was investigated by viscometry, gel permeation chromatography (GPC), and GPC combined with laser light scattering (GPC‐LLS) techniques. 3,6‐O‐CM‐chitin has a strong tendency to form aggregates in NaCl aqueous solutions with the apparent aggregation number (Nap) of about 27. There were three kinds of aggregates corresponding to different cohesive energies, the aggregates with low cohesive energy were first dissociated at 60°C, the aggregates with middle cohesive energy were then dissociated at 80 to 90°C, and the aggregates with high cohesive energy were difficult to be disrupted by heating. Decreasing polysaccharide concentration (cp) or increasing NaCl concentration (cs) reduced the content of the aggregates. At the critical cp of 2.5 × 10−5 g/mL, the aggregates were dissociated into single chains completely. The change of aggregation and disaggregation of 3,6‐O‐CM‐chitin in water–cadoxen mixtures occurred from 0.1 to 0.4 of vcad, and were irreversible. Intermolecular hydrogen bonding can be ascribed as main driving force for aggregation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1838–1843, 2002

Amphiphilic diblock, triblock, and star block copolymers by living radical polymerization: Synthesis and aggregation behavior

AbstractCopper(I)‐mediated living radical polymerization was used to synthesize amphiphilic block copolymers of poly(n‐butyl methacrylate) [P(n‐BMA)] and poly[(2‐dimethylamino)ethyl methacrylate] (PDMAEMA). Functionalized bromo P(n‐BMA) macroinitiators were prepared from monofunctional, difunctional, and trifunctional initiators: 2‐bromo‐2‐methylpropionic acid 4‐methoxyphenyl ester, 1,4‐(2′‐bromo‐2′‐methyl‐propionate)benzene, and 1,3,5‐(2′‐bromo‐2′‐methylpropionato)benzene. The living nature of the polymerizations involved was investigated in each case, leading to narrow‐polydispersity polymers for which the number‐average molecular weight increased fairly linearly with time with good first‐order kinetics in the monomer. These macroinitiators were subsequently used for the polymerization of (2‐dimethylamino)ethyl methacrylate to obtain well‐defined [P(n‐BMA)x‐b‐PDMAEMAy]z diblock (15,900; polydispersity index = 1.60), triblock (23,200; polydispersity index = 1.24), and star block copolymers (50,700; polydispersity index = 1.46). Amphiphilic block copolymers contained between 60 and 80 mol % hydrophilic PDMAEMA blocks to solubilize them in water. The polymers were quaternized with methyl iodide to render them even more hydrophilic. The aggregation behavior of these copolymers was investigated with fluorescence spectroscopy and dynamic light scattering. For blocks of similar comonomer compositions, the apparent critical aggregation concentration (cac = 3.22–7.13 × 10−3 g L−1) and the aggregate size (ca. 65 nm) were both dependent on the copolymer architecture. However, for the same copolymer structure, increasing the hydrophilic PDMAEMA block length had little effect on the cac but resulted in a change in the aggregate size. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 439–450, 2002; DOI 10.1002/pola.10122

Mitotic Golgi is in a dynamic equilibrium between clustered and free vesicles independent of the ER.

Golgi inheritance during cell division involves Golgi disassembly but it remains unclear whether the breakdown product is dispersed vesicles, clusters of vesicles or a fused ER/Golgi network. Evidence against the fused ER/Golgi hypothesis was previously obtained from subcellular fractionation studies, but left concerns about the means used to obtain and disrupt mitotic cells. Here, we performed velocity gradient analysis on otherwise untreated cells shaken from plates 9 h after release from an S-phase block. In addition, we used digitonin and freeze/thaw permeabilization as alternatives to mechanical homogenization. Under each of these conditions, approximately 75% of the Golgi was recovered in a population of small vesicles that lacked detectable ER. We also used multilabel fluorescent microscopy with optical sectioning by deconvolution to compare the 3D metaphase staining pattern of endogenous Golgi and ER markers. Although both ER and Golgi staining were primarily diffuse, only the ER was excluded from the mitotic spindle region. Surprisingly, only 2% of the Golgi fluorescence was present as resolvable structures previously characterized as vesicle clusters. These were not present in the ER pattern. Significantly, a portion of the diffuse Golgi fluorescence, presumably representing dispersed 60-nm vesicles, underwent an apparent rapid aggregation with the larger Golgi structures upon treatments that impaired microtubule integrity. Therefore, mitotic Golgi appears to be in a dynamic equilibrium between clustered and free vesicles, and accurate partitioning may be facilitated by microtubule-based motors acting on the clusters to insure random and uniform distribution of the vesicles.

Ant-nest distribution in a remnant of tropical rainforest in southeastern Brazil

Ant communities are generally extremely interactive, and competition between ant species seems to be widespread. This characteristic of ant communities tends to produce a uniform pattern of nest distribution. In this study, we aimed to test the nest distribution pattern, putting forward hypotheses to explain the pattern. Nest mapping was carried out by delimiting ten one-square-meter quadrats, randomly located in a remnant of tropical rainforest in Vicosa, Brazil. In each quadrat, the nests were surveyed in the litter and surface soil up to 3 cm deep. A total of 295 nests from 41 ant species were collected in the ten quadrats. The pattern of nest distribution in the whole forest was aggregated, while the species showed a random distribution. The pattern of nest distribution inside each quadrat was also aggregated. The presence of species, such as Brachymyrmex sp.1 and Hypoponera sp.4 , with high nest densities suggests the occurrence of nest budding. This may be the reason for the aggregated nest distribution. Another explanation for this apparent aggregation is species specialization in a patchily distributed habitat. The results suggest that competition is not an important process in the regulation of soil and litter ants distribution and, consequently, in the regulation of species richness in the studied area.

On the Aggregation Behavior of Pseudoisocyanine Chloride in Aqueous Solution as Probed by UV/vis Spectroscopy and Static Light Scattering

In this work, the aggregation behavior of the cyanine dye, pseudoisocyanine chloride, in aqueous solutions both in the absence and presence of added electrolyte (0.01 M NaCl) was studied by a combination of UV/vis spectroscopy and static light scattering (SLS). In the case of pure aqueous dyestuff solutions, an apparent aggregation number of Napp ∼ 3 was found. A correction of the apparent molecular weights, MW,app, for the amount of the still present residual monomers gave only slightly larger values (N ∼ 4). However, it could be shown that, in the presence of 0.01 M NaCl at low dyestuff concentration (0.75 × 10-3 mol L-1), the absorption spectrum shows the typical features of what is commonly believed to represent a dimer spectrum, whereas the corresponding SLS data unequivocally prove the existence of larger aggregates, consisting of at least 30 molecules. At higher dyestuff concentrations (∼2 × 10-3 mol L-1) and in the presence of salt, apparent aggregation numbers of ∼1000 (uncorrected) and ∼2000 (co...

Side-chain micellization in random copolymers of sodium acrylate and methacrylates substituted with nonionic surfactant moieties: a comparison with sodium 2-(acrylamido)-2-methylpropanesulfonate copolymers

The micelle formation of random copolymers of sodium acrylate (NaAA) and a methacrylate substituted with HO(CH 2CH 2O) m C 12H 25 (C 12E m ) where m=2, 6 or 25 (DE mMA) in 0.1 M NaCl aqueous solutions at pH=10 was investigated in comparison with that of random copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate (NaAMPS) and DE mMA. Apparent critical micelle concentrations and aggregation numbers of the polymer-bound C 12E m moieties in micelles formed from the NaAA-based copolymers of m=2, 6 and 25 were nearly the same as those found for the NaAMPS-based copolymers of m=2, 6 and 25 comparing at the same m. Zero-shear viscosity ( η 0) increased gradually with increasing polymer concentration ( C p) in a dilute regime, followed by a drastic increase at higher C p, which is a common feature for both the copolymers. However, the dependence of η 0 on m for the NaAA copolymers is completely opposite to that for the NaAMPS copolymers. In a semidilute regime, η 0 for the NaAA copolymer of m=2 was ca. 3 and 6 orders of magnitude higher than those of the NaAA copolymers with m=6 and 25, respectively, whereas η 0 for the NaAMPS copolymer of m=2 was ca. 1 and 3 orders of magnitude lower than those of the NaAMPS copolymers with m=6 and 25, respectively. At m=2, η 0 for the NaAA copolymer is ca. 8 orders of magnitude higher than that for the NaAMPS copolymer. This large difference in the viscosity behavior of the NaAA- and NaAMPS-based copolymers was attributed to a much stronger tendency of the NaAA-based copolymer to undergo interpolymer association when m is small.

Analysis of aggregation, a worked example: numbers of ticks on red grouse chicks.

The statistical aggregation of parasites among hosts is often described empirically by the negative binomial (Poisson-gamma) distribution. Alternatively, the Poisson-lognormal model can be used. This has the advantage that it can be fitted as a generalized linear mixed model, thereby quantifying the sources of aggregation in terms of both fixed and random effects. We give a worked example, assigning aggregation in the distribution of sheep ticks Ixodes ricinus on red grouse Lagopus lagopus scoticus chicks to temporal (year), spatial (altitude and location), brood and individual effects. Apparent aggregation among random individuals in random broods fell 8-fold when spatial and temporal effects had been accounted for.

Aggregation and disaggregation of Aeromonas gum in an aqueous solution under different conditions

The aggregation and disaggregation ofAeromonas (A) gum, an acidic heteropolysaccharide, were investigated by viscometry, a fluorescent probe, and gel permeation chromatography combined with laser light scattering techniques in aqueous solutions containing desired NaCl at different temperatures. The A gum had a strong tendency of aggregation and high viscosity in the aqueous solutions. The weight-average molecular weight, z-average radius of gyration, weight-average molar number (w ag ), and apparent aggregation number (N ap ) of the aggregates were investigated and discussed. The results indicated that there were three regions that corresponded to three kinds of aggregates and two transition temperatures at about 35 and 75 °C in the disaggregation course. When the temperature was higher than 75 °C, the w ag hardly changed, and there was still a certain amount of aggregates even at 100 °C, indicating that the aggregates were difficult to disrupt completely. Moreover, the aggregation was thermally irreversible. Decreasing polysaccharide concentration reduced the content of the aggregate. However, N ap remained constant around 20, independent of the polysaccharide concentration in a 0.5 M NaCl aqueous solution at 25 °C. At a salt concentration greater than or equal to 0.05 M, the aggregation was almost independent of the salt concentration used here.