Robert Ernst

Solubilization of membrane proteins by sulfobetaines, novel zwitterionic surfactants

Abstract A homologous series of novel zwitterionic detergents, sulfobestaines (SB n ), was examined for its ability to emulsify a triglyceride model system and to extract proteins from 3T6 mouse fibroblast membranes. In both instances the solubilization efficiency of SB n s was found to improve with increasing alkyl chain length ( n ). The higher alkyl SB n s ( n ≥ 12) were shown to be superior to nonionic detergents of the polyoxyethelene type (e.g., Nonidet P-40) but inferior to the anionic SDS in their ability to solubilize 3T6 cell membrane proteins. However, unlike SDS, SB n s apparently do not denature either water-soluble or membrane proteins, as judged by retention of enzymatic activity.

Effects of thidiazuron on in vitro propagation of Phalaenopsis and Doritaenopsis (Orchidaceae)

Phalaenopsis or Doritaenopsis (Orchidaceae) flower stem sections cultivated in vitro on media containing 0.23–11.35 μM of N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron, TDZ) developed generally multiple shoots with the higher levels producing also protocorm-like bodies (PLB). Shoot and root development were reduced while proliferation increased with increasing concentration of TDZ. Similar effects were observed with Phalaenopsis protocorms at a lower range (0.23–1.14 μM) of TDZ.

Biological effects of surfactants, IV. Effects of non-ionics and amphoterics on HeLa cells

Surfactants, representing 3 non-ionic and 1 amphoteric series of homologs exhibited marked differences in their lethal and non-toxic effects on HeLa cells. Toxicity of non-ionics generally decreased inversely with increasing hydrophilic chain length and increased with increasing size of the lipophile. Lethal levels of the surfactants coincided with surface tension reduction of the media to 45 dynes cm-1 or below. Surface tensions of non-toxic concentrations were substantially higher than those for toxic levels. Non-toxic doses were, therefore, below the critical micelle concentration of the surfactants evaluated. The data suggest that physical properties are a principal cause of the toxic effects of these detergents on HeLa cells.

Biological effects of surfactants: Part 6—effects of anionic, non-ionic and amphoteric surfactants on a green alga (Chlamydomonas)

Abstract The well known algistatic effect of cationic surfactants was not exhibited by homologous series of amphoteric, anionic and non-ionic types assayed with Chlamydomonas reinhardi. Sulphobetaine amphoterics, 3-(octyl-octadecyldimethylammonio)-1-propanesulphonates, caused growth inhibition when the lipophile contained twelve or more carbon atoms, but only at micellar concentrations. Critical micelle concentration (CMC) of sulphobetaines decreases logarithmically with increasing alkyl chain length and derivatives having eight and ten carbons in the lipophile were below the CMC at the highest concentration tested. Despite their pronounced protein-denaturing properties, sodium higher alkylsulphates did not materially inhibit the growth of Chlamydomonas. This may be due to the fact that the Kraft points of these anionics having fourteen or more carbon atoms were above the culture temperatures, thereby reducing their solution properties. Although less inhibiting than the sulphobetains, the non-ionic alcohol ethoxylates decreased growth with increasing hydrophilicity. The most lipophilic non-ionic showed growth-promoting effects.

Biological effects of surfactants, III hydra as a highly sensitive assay animal

Abstract Effects on hydra of five homologous series of surfactants representing nonionic, amphoteric and anionic classes were examined. When concentrations which had no effects were increased tenfold the animal disintegrated within 24 h. Lethal concentrations always coincided with a surface tension of 49 ± 4 dynes/cm. This is probably the level which disrupts the cell membranes. Because the deleterious effects are very rapid and obvious, hydra is a useful organism for monitoring the potential toxicity of detergents in freshwater environments.

Design, synthesis and application of surface-active chemicals for the promotion of electrofusion of plant protoplasts

Abstract To provide milder, and thus less destructive, electrical conditions without reduced fusion rates a combination of chemofusion and electrofusion techniques was successfully applied to isolated plant protoplasts. Chemical adjuvants were employed for pretreatment of the protoplasts, added to the fusion medium during electroapplication and left in the culture medium in order to maintain the most obvious advantage of electrofusion, i.e. direct culture in the fusion medium without the need for washing procedures to remove fusion-promoting substances. Eight chemicals were investigated in the chemostimulated electrofusion and five proved to be positively effective and non-toxic to the cells in culture. Calluses were successfully induced. These chemicals are l -α-lyso(stearoyl/palmitoyl)phosphatidyl cholinium chloride (LLCC), quaternary starch (QS), di-[poly(oxyethylene)ethanol]-stearylammonium chloride (DSC), di-[poly(oxyethylene)ethanol]-stearylamine (DSA) and polyvinylalcohol (PVA). Among these five chemicals, the latter three gave the most promising results. DSC can cause a relative fusion rate of up to 2.15 with a normal (non-reduced) electrical field and 1.94 with a milder less damaging field. DSA gave the highest relative fusion rate under reduced electrofusion conditions (1.72). PVA triggered relative fusion rates as high as 2.21 under normal electrical conditions and 1.26 under milder conditions.