A ligand-receptor model for the cohesive behaviour of Dictyostelium discoideum axenic cells

Axenically grown cells of D. discoideum Ax-2 harvested in the log phase of growth, cohere rapidly when shaken in phosphate buffer. After 3.5 days in the stationary phase of growth, cells become completely non-cohesive. Although they do not stick to each other, stationary phase cells do stick to both log phase cells and aggregation-competent cells. The cohesion of stationary phase cells with these other 2 cell types is inhibited by both EDTA and the low-molecular-weight factor which we have previously demonstrated in stationary-phase growth medium. There is a decline in the sensitivity of slime mould cell cohesion to the low-molecular-weight inhibitory factor as the cells become aggregation-competent. This effect parallels the developmentally-regulated decline in sensitivity to EDTA. The low-molecular-weight inhibitor is not a chelating agent, however. The effect of the inhibitor seems to be specifically against contact sites-B mediated cohesion. We suggest that the simplest cohesive mechanism which can explain our results, is that the EDTA-sensitive cohesion of log phase cells could be dependent on a ligand-receptor system.

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Effect of Organic Modifier on the Retention of Low-Molecular-Weight Organic Compounds in Low-Temperature HPLC Using a Liquid CO2 Mobile Phase and an Octadecyl Stationary Phase

Chromatography ◽

10.15583/jpchrom.2020.025 ◽

2021 ◽

Author(s):

Kohei MATSUO ◽

Mina OTSUBO ◽

Tomohiro MOTONO ◽

Shinya KITAGAWA ◽

Yoshinori IIGUNI ◽

...

Keyword(s):

Molecular Weight ◽

Low Temperature ◽

Stationary Phase ◽

Organic Compounds ◽

Mobile Phase ◽

Low Molecular Weight ◽

Organic Modifier

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The nature of conditioning nutrients for human malignant melanoma cultures

Journal of Cell Science ◽

10.1242/jcs.62.1.249 ◽

1983 ◽

Vol 62 (1) ◽

pp. 249-266

Author(s):

K.A. Ellem ◽

G.F. Kay

Keyword(s):

Molecular Weight ◽

Cell Density ◽

Cell Attachment ◽

Cell Types ◽

Fresh Medium ◽

Low Molecular Weight ◽

High Concentration ◽

Cell Content ◽

Human Malignant Melanoma ◽

Serum Factors

From a human melanoma line (MM96), showing some dependence of its rate of growth and cell attachment on serum concentration, sublines were selected for even greater dependence on serum factors. These sublines were used to identify the production of substances by other melanoma cells in culture that would supplement or replace the requirement for serum. Most of the sublines showed higher colony-forming efficiency in medium conditioned by one of several cell types in the presence of a low concentration of serum (2.5%) compared with fresh medium containing a high concentration of serum (10%). The conditioning factor(s) were found to be moderately heat-stable, nonlipophilic, and to be of low molecular weight (less than or greater than 400). Screening of a variety of non-essential low molecular weight nutrients, which have been reported to potentiate the growth of a variety of cell types in low-density culture, was positive for the MM96 sublines only for pyruvate. In particular, L-alanine, L-serine, putrescine and alpha MSH (melanocyte-stimulating hormone) were ineffective. Despite the problems of comparing conditioned media with fresh medium, a reasonable correlation between the stimulatory effect and the cell content of added 2-oxocarboxylates was apparent. As would be anticipated, MM96 cultures showed a population density-dependent enhancement of growth up to a cell density of 2 to 4 × 10(4) cells cm-2. Further increase in the initial cell density of these cultures led to a decline in growth rate. An important additional observation was that simple dilution of the ingredients of RPMI1640 with phosphate-buffered saline or Hanks' balanced salt solution led to a reversal of growth inhibition accompanying a serum shift-down.

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Liquid Chromatographic Separations Using Rubber as the Stationary Phase

Rubber Chemistry and Technology ◽

10.5254/1.3539550 ◽

1963 ◽

Vol 36 (1) ◽

pp. 310-312

Author(s):

P. I. Brewer

Keyword(s):

Molecular Weight ◽

Stationary Phase ◽

Mobile Phase ◽

Chromatographic Method ◽

Mineral Oil ◽

Low Molecular Weight ◽

Chromatographic Separations ◽

Liquid Chromatographic Method ◽

Crosslinked Polystyrene ◽

Liquid Chromatographic

Abstract In a previous communication it was reported that certain polymers could be separated from mineral oil by a liquid chromatographic method. n-Heptane was used as the mobile phase and small pieces of thin vulcanized natural latex as the stationary phase. It has now been found that compounds of lower molecular weight can also be separated by this method. The use of rubber for the separation of compounds of low molecular weight was first described by Boldingh; he found it advantageous first to swell the rubber with a different solvent from that used as the mobile phase. The use of a crosslinked dextran (“Sephadex”) for separating compounds in aqueous solution has been described by Gelotte. Vaughan has mentioned the possibility of using crosslinked polystyrene beads for this purpose.

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Low molecular weight nonheme iron and a highly labeled heme pool in the reticulocyte

Blood ◽

10.1182/blood.v56.3.564.564 ◽

1980 ◽

Vol 56 (3) ◽

pp. 564-566 ◽

Cited By ~ 15

Author(s):

S Pollack ◽

T Campana

Keyword(s):

Molecular Weight ◽

Guinea Pig ◽

Specific Activity ◽

Chelating Agent ◽

Nonheme Iron ◽

Low Molecular Weight ◽

Alpha Chain ◽

Molecular Weight Peak ◽

First Time

Abstract The ligands that bind iron and heme in reticulocyte and may regulate their distribution are not known. Guinea pig reticulocyte hemolysates were labeled with 59Fe and filtered through molecular weight sieving columns. 59Fe-containing peaks of ferritin, transferrin, and hemoglobin were identified, as well as a low molecular weight peak containing predominantly nonheme iron, and a 17,000 mol wt heme containing peak with a specific activity (59Fe/heme) 20-fold greater than hemoglobin. We note that the low molecular weight peak, the existence of which has been postulated, has been identified for the first time without the addition of a chelating agent. We speculate that the 17,000 mol wt peak is an alpha-chain pool.

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Photocatalytic reduction of Cr(vi) by graphene oxide materials under sunlight or visible light: the effects of low-molecular-weight chemicals

Environmental Science Nano ◽

10.1039/d0en00329h ◽

2020 ◽

Vol 7 (8) ◽

pp. 2399-2409

Author(s):

Shang-Shing Wu ◽

Wen-Che Hou ◽

David K. Wang

Keyword(s):

Molecular Weight ◽

Graphene Oxide ◽

Visible Light ◽

Electron Donor ◽

Chelating Agent ◽

Photocatalytic Reduction ◽

Low Molecular Weight ◽

Oxide Materials

GO rapidly photocatalyzes the reduction of Cr(vi) utilizing sunlight in the presence of oxalate that acts as an electron donor and chelating agent.

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Low molecular weight nonheme iron and a highly labeled heme pool in the reticulocyte

Blood ◽

10.1182/blood.v56.3.564.bloodjournal563564 ◽

1980 ◽

Vol 56 (3) ◽

pp. 564-566

Author(s):

S Pollack ◽

T Campana

Keyword(s):

Molecular Weight ◽

Guinea Pig ◽

Specific Activity ◽

Chelating Agent ◽

Nonheme Iron ◽

Low Molecular Weight ◽

Alpha Chain ◽

Molecular Weight Peak ◽

First Time

The ligands that bind iron and heme in reticulocyte and may regulate their distribution are not known. Guinea pig reticulocyte hemolysates were labeled with 59Fe and filtered through molecular weight sieving columns. 59Fe-containing peaks of ferritin, transferrin, and hemoglobin were identified, as well as a low molecular weight peak containing predominantly nonheme iron, and a 17,000 mol wt heme containing peak with a specific activity (59Fe/heme) 20-fold greater than hemoglobin. We note that the low molecular weight peak, the existence of which has been postulated, has been identified for the first time without the addition of a chelating agent. We speculate that the 17,000 mol wt peak is an alpha-chain pool.

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