PubMed · 720577
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T V Koval'chuk, A Ia Kobzar. [Rapid method for checking dimethyl sulfoxide solutions].. https://pubmed.ncbi.nlm.nih.gov/720577/
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Dimethylsulfoxide (DMSO) is known to protect isolated enzymes during freezing while destabilizing proteins at high temperatures. This apparent paradox is the subject of a review by Arakawa et al. ((1990) Cryobiology 27, 401-415), who present evidence for a temperature-dependent, hydrophobic interaction between DMSO and non-polar moieties of proteins. The present study investigates the interaction of DMSO with phospholipid bilayers. Phospholipid vesicles containing carboxyfluorescein were exposed to several concentrations of DMSO at various temperatures. Leakage rates increased with DMSO concentration and temperature. This effect was not reduced in the presence of solutes that have been shown to neutralize DMSO toxicity in tissues. The increased leakage rates correlate well with the increased partitioning of DMSO from water to octanol at higher temperatures. Additionally, reductions in the CH2 vibrations of the bilayer are also shown to depend on DMSO concentration and temperature. A similar reduction in CH2 vibrations was observed in solutions of octanol and DMSO, suggesting that this effect is not mediated through an interaction with water. Furthermore, investigation of sulfoxide vibrations indicate that DMSO is not hydrogen bonded to the alcohol moiety of octanol, and therefore the interaction between DMSO and octanol is most likely due to a hydrophobic association. These results are consistent with a destabilization of phospholipid membranes at higher temperatures due to a hydrophobic association between DMSO and the bilayer.
The effects of the organic osmolyte beta-dimethylsulfoniopropionate (DMSP) on the structural stability of three model proteins were examined to determine whether DMSP, like the structurally similar solute dimethyl sulfoxide (DMSO), is compatible with native protein structure at low, but not elevated, temperatures. DMSP stabilized phosphofructokinase under conditions of cold-induced denaturation. Thus, DMSP, like DMSO, may be an effective protein cryoprotectant. However, DMSP was not an effective stabilizer of protein structure under conditions of heat denaturation. Whereas low (0.2 M) concentrations of DMSP stabilized lactate dehydrogenase against inactivation at 50 degrees C, higher DMSP concentrations were ineffective. DMSP favored the denaturation of glutamate dehydrogenase at all DMSP concentrations tested. DMSP may be a compatible osmotic solute only under conditions of moderate temperature and low, yet physiological, concentrations. The mechanistic basis of DMSP's temperature- and concentration-dependent effects and the possible roles played by adaptation temperature and severity of osmotic stress in the evolutionary selection of organic osmolytes are discussed.
The ultrastructure of the follicle-oocyte complex in rodents and humans was revealed by high resolution scanning electron microscopy (SEM) following the Osmium-DMSO-Osmium maceration method (TANAKA and NAGURO, 1981). In primary follicles, the majority of oocyte organelles such as mitochondria and Golgi complex components are concentrated in a juxtanuclear area. In particular, many spherical mitochondria are oriented all around the nucleus. After maceration of the ooplasm matrix, most of these mitochondria appear intermingled with numerous microtubules (MT) and associated with many Golgi vesicles. Such a nuclear polarization of organelles, essential to the oocyte metabolism, might depend upon a MT activity. MT might guide mitochondria to gather in the perinuclear region and further maintain their close associated to the nuclear envelope. A similar relationship among microtubules, vesicular Golgi complex and mitochondria has been also observed when, in maturing oocytes, these organelles migrate and gather in other areas of the ooplasm. A pattern common only to human developing follicles appears in the occurrence of long microvilli projected from follicle cells deep into the oocyte. These unusual microvilli running within the ooplasm are surrounded by several vesicles of the Golgi complex and endoplasmic reticulum, and often end close to the nucleus. In the antral follicle, the microvilli of corona cells, directed toward the oocyte (after their full exposure through the chemical dissolution of the zona pellucida matrix) are extremely numerous (up to 70/cell), long (up to 7/10 microns) and tortuous. They resemble epididymal stereocilia, may be ramified and possess bulbous tips. In contrast, oocyte microvilli are thin and short.(ABSTRACT TRUNCATED AT 250 WORDS)