Synthesis of α- and

Abstract

An attempt was made to determine the nature, origin, and fate of the membrane material of osmiophilic lamellated bodies, using lung tissue from neonate rats. The cytoplasm of the type II alveolar pneumonocyte contains centrioles, multivesicular bodies, and minute free vesicles similar to those in the multivesicular bodies. Autolysosomes, comprising membrane-bounded cytoplasmic regions and osmiophilic lamellated material, also occur in the type II pneumonocytes. The mitochondria often contain concentric membrane accumulations and membranous whorls. The type II alveolar cells are characterised by an intensive autophagy; this is apparently correlated with glycogenolysis, and with a radical cytodifferentiation by which the cells transform to the type I pneumonocyte. The osmiophilic lamellae of the autolysosomes are probably emptied isolation membranes. The mitochondria possibly serve as repositories for the massive membrane accumulations remaining after cytoplasmic lysis, which may invaginate into the organelles. The osmiophilic lamellated bodies typical of type II alveolar pneumonocytes may be mitochondrial membranes packed with the residual membranous material. Myeloid matter in the alveolar spaces (derived from the osmiophilic lamellated bodies) is best interpreted, not as an organised secretory product, but rather as a residue of cellular autophagy.     

The alveolar epithelium of the newborn rat,and the significance of the osmiophilic lamellated bodies in cellular autophagy

Abstract

An attempt was made to determine the nature, origin, and fate of the membrane material of osmiophilic lamellated bodies, using lung tissue from neonate rats. The cytoplasm of the type II alveolar pneumonocyte contains centrioles, multivesicular bodies, and minute free vesicles similar to those in the multivesicular bodies. Autolysosomes, comprising membrane-bounded cytoplasmic regions and osmiophilic lamellated material, also occur in the type II pneumonocytes. The mitochondria often contain concentric membrane accumulations and membranous whorls. The type II alveolar cells are characterised by an intensive autophagy; this is apparently correlated with glycogenolysis, and with a radical cytodifferentiation by which the cells transform to the type I pneumonocyte. The osmiophilic lamellae of the autolysosomes are probably emptied isolation membranes. The mitochondria possibly serve as repositories for the massive membrane accumulations remaining after cytoplasmic lysis, which may invaginate into the organelles. The osmiophilic lamellated bodies typical of type II alveolar pneumonocytes may be mitochondrial membranes packed with the residual membranous material. Myeloid matter in the alveolar spaces (derived from the osmiophilic lamellated bodies) is best interpreted, not as an organised secretory product, but rather as a residue of cellular autophagy.     

Fine Structure of the Marine Amoeba Vexillifera telmathalassa Collected from a Coastal Site Near Barbados with a Description of Salinity Tolerance, Feeding Behavior and Prey

ABSTRACT. Amoebae cultured from seawater collected at a coastal site near Barbados were largely a lobose amoeba with long tapered subpseudopodia identified as Vexillifera telmathalassa. Vexillifera telmathalassa occurs widely in marine environments and additional information is presented here on its fine structure, salinity tolerance, and feeding behavior toward clarification of its taxonomic characteristics and ecological niche. The amoebae were able to adjust to a gradual decline in salinity from 36‰ to 16‰, but at a salinity of 12‰. They all became immobilized and discoidal. The fine structure showed a centrally located nucleus (2.1 μ m) with a prominent nucleolus. The plasma membrane is coated with glycostyles 17 nm long and 14 nm apart, and may be derived from secretory vesicles with similar glycocalyx lining. Bacteria and occasional eukaryotic remains occur in digestive vacuoles or membrane-enclosed spaces. Some vacuoles (2.0–2.5 μ m) are filled with scattered masses of digested material and resemble the "glanzkörper" previously identified by light microscopy. In addition to bacterial prey, microflagellates were also ingested in laboratory culture as observed by light microscopy. Vexillifera telmathalassa may be more closely linked trophically to the microbial loop than previously recognized.     

In vivo interaction of antibodies with cell surface proteins used as antigens

Antibody interactions with cell membrane glycoproteins in vivo exhibit features of aggregation and capping with resultant shedding similar to those events described in several in vitro isolated cell systems. Requirements for divalent ligand binding and participation of cytoskeletal elements are demonstrated in vivo as well. Persistence of antigen in immune complexes with complement interaction in situ appear to be necessary to induce an inflammatory response in vivo. Abrogation of this response occurs when circumstances permit antigenic modulation with disappearance of the immune complex.     

Cell surface structure as a taxonomic character in the Thecamoebidae (Protozoa: Gymnamoebia)

Amoebae of the genera Thecamoeba, Platyamoeba , and Vannella , Family Thecamoebidae, have a surface layer which in one or more species of each genus has been found cytochemically to be a glycocalyx or mucoid coating. In six species of Thecamoeba , this is a compact coat, sometimes with a less dense outer region, 16–73 nm thick according to species. 7". proteoides , in other respects intermediate between Thecamoeba and Amoeba , has a filamentous layer up to 78 nm thick, somewhat like those of Amoeba and Chaos. T. granifera has a coating or tegument more than 0.5 Jim thick, differing structurally and cytochemically from the glycocalyces of the other species, and is the type-species of a new genus Dermamoeba. All six species of Platyamoeba investigated, freshwater and marine, had similar glycocalyces, consisting of a thin, dense inner layer and a thicker, lighter, outer layer. Two species of Vannella from North America bear complex structures here called glycostyles, corresponding in structure and size to those of V. simplex from Germany. There is an essential similarity between most species of Thecamoeba and the related Sappinia. Surface structure distinguishes clearly between Platyamoeba and Vannella but does not support fragmentation of the genus Platyamoeba. Although surface structure is of considerable taxonomic value at the generic level in the Thecamoebidae and may assist in confirming identification of some Thecamoeba species, it is less promising for differentiation of species within Platyamoeba and Vannella.     

High-resolution visualization of the microbial glycocalyx with low-voltage scanning electron microscopy: dependence on cationic dyes.

The microbial glycocalyx is composed of a variety of polyanionic exopolysaccharides and plays important roles in microbial attachment to different substrata and to other cells. Here we report the successful use of low-voltage scanning electron microscopy (LVSEM) to visualize the glycocalyx in two microbial models (Klebsiella pneumoniae and Enterococcus faecalis biofilms) at high resolution, and also the dependence on fixation containing polycationic dyes for its visualization. Fixation in a paraformaldehyde-glutaraldehyde cocktail without cationic dyes was inadequate for visualizing the glycocalyx, whereas addition of various dyes (alcian blue, safranin, and ruthenium red) to the aldehyde cocktail appeared necessary for stabilization. The cationic dyes varied in size, shape, and charge density, and these factors appeared responsible for different phenotypic appearances of the glycocalyx with each dye. These results suggest that aldehyde fixation with cationic dyes for high-resolution LVSEM will be a useful tool for investigation of microbial biofilms as well as investigation of the extent and role of the glycocalyx in microbial attachment to surfaces.     

Glycosaminoglycans of the fat globule membrane of cow milk

Membranes of fat globules of cow milk contained 163 μg/100 mg (dry weight) of glycosaminoglycans (expressed as uronic acid); 62.5% of the uronic acids corresponded to hyaluronic acid, the remaining consisted of sulfated glycosaminoglycans (chondroitin-4-(-6) sulfates, and dermatan and heparan sulfates) with different degrees of sulfation.     

Fine structure and cytochemical evidence for the presence of polysaccharide surface coat of Dirofilaria immitis microfilariae

Cherian P. V., Stromberg B. E., Weiner D. J. and Soulsby E. J. L. 1980. Fine structure and cytochemical evidence for the presence of polysaccharide surface coat of Dirofilaria immitis microfilariae. International Journal for Parasitology10: 227–233. Cytochemical staining techniques were employed at the fine structural level using ruthenium red, ruthenium violet and Alcian blue-lanthanum nitrate to demonstrate the polysaccharide rich surface coat of Dirofilaria immitis microfilariae. The coat matrix present at the external surface of the cuticle of microfilariae stained densely with each of the polycationic dyes. The reaction products were restricted to the outer surface of the cuticle suggesting that the polycationic dyes did not penetrate the cuticle. The junctions of the cuticular annulations lacked surface coat matrix and reaction products which might be indicative of the absence of carbohydrate residues or the masking of reactive sugar molecules in these areas. The speciflcity of the reaction was indicated by the absence of reaction products in untreated organisms. These carbohydrate moieties probably represent glycoproteins as structural constituents of the parasite surface. Ultrastructural analysis of the surface of microfilariae is of signiflcance in elucidating both the molecular dynamics of the parasite surface and its immunological function in the host.