Related Experiment Videos
Chemical and ultrastructural differences in endotoxic glycolipids from Salmonella minnesota Re mutant extracted with
Abstract:
Endotoxic glycolipids ( ReGl ) extracted from the whole cells (WC) and cell walls of heptose-less Re mutant of Salmonella minnesota with hot phenol-water (PW), phenol-chloroform-petroleum ether (PCP), and chloroform-methanol (CM) were analyzed chemically and examined with an electron microscope. ReGl -PW-(WC) contained mannose and proteins as contaminants, ReGl -PCP(WC) consisted of an excess amount of amino compound (cadaverine), and ReGl -PCP(WC) consisted of proteins and cadaverine, in addition to the ReGl constituents. The ultrastructure of ReGl -PW(WC) resembled onions when stained with uranyl formate, and was spherical when stained with uranyl acetate, sodium phosphotungstate and ammonium molybdate, whereas those of ReGl -PCP(WC) and ReGl -CM(WC) were shaped like ribbons. However, the shadowed ultrastructures of ReGl -PCP(WC) and ReGl -CM(WC) showed small pieces of flat and wide sheets, respectively. ReGl -PCP(WC) re-extracted by the PW method was found to be converted into the onion-like structure which was similar to that of ReGl -PW(WC), while an intermediate form (fingerprint-like) was observed after re-extraction of ReGl -PW(WC) with PCP. It was strongly suggested that the ultrastructural arrangement of ReGl was dependent on the solvent systems used for extraction.
Insights
The extraction solvent significantly impacts the ultrastructure of endotoxic glycolipids from Salmonella minnesota. Different solvents yield distinct structural forms, influencing their appearance under electron microscopy.
Area of Science:
- Microbiology
- Biochemistry
- Structural Biology
Background:
- Endotoxic glycolipids (ReGl) are crucial components of Gram-negative bacteria.
- The structure of ReGl can influence its biological activity and interactions.
- Salmonella minnesota is a model organism for studying lipopolysaccharides.
Purpose of the Study:
- To investigate the chemical composition and ultrastructure of ReGl.
- To determine the effect of different extraction solvents on ReGl morphology.
- To analyze the structural transformation of ReGl upon re-extraction.
Main Methods:
- Extraction of ReGl from Salmonella minnesota using phenol-water (PW), phenol-chloroform-petroleum ether (PCP), and chloroform-methanol (CM).
- Chemical analysis to identify contaminants and constituents.
- Electron microscopy (including shadowing) to examine ultrastructure.
Main Results:
- ReGl extracted with PW contained mannose and proteins; PCP and CM extracts had amino compounds (cadaverine) and proteins.
- PW-extracted ReGl showed onion-like or spherical structures, while PCP and CM extracts formed ribbon-like structures.
- Re-extraction experiments demonstrated solvent-dependent structural conversions, including fingerprint-like intermediate forms.
Conclusions:
- The ultrastructural arrangement of ReGl is highly dependent on the solvent systems employed during extraction.
- Different extraction methods lead to distinct ReGl morphologies, potentially affecting their properties.
- Understanding these solvent-induced structural changes is vital for accurate ReGl characterization.