A glycogen storage disease in rats. Morphological and biochemical investigations

Liver and heart from a substrain of the NZR/Gd rat in which there is an inherited deficiency of liver phosphorylase b kinase was examined by light and electron microscopy and compared to material from a related, but normal substrain. Hepatic tissue differed markedly from that of control animals. Hepatocytes contained more than twice as much free glycogen and visible lipid. Glycogen particles had an abnormal appearance and some glycogen was sequestered within large, membrane-bound vesicles. Hepatocyte lysosomes were increased by a third and mean cell volume by more than half. Lobular architecture was distorted by the presence of enlarged, irregularly-shaped hepatocytes. Free glycogen was present in the space of Disse and sinusoids and within lysosomes in Kupffer cells. There were increased amounts of collagen in the space of Disse. The changes resemble those described in human glycogen storage disease IXa. A study of hepatic tissue from fasted rats showed that affected animals have an impaired ability to mobilise their liver glycogen stores. An increase in visible lipid also occurred in affected, fasted animals. Cardiac tissue appeared to be normal.     

Fulminating necrotizing amebic colitis with perforation: case report and review.

A seriously ill patient with diffuse abdominal tenderness of unknown cause is described. The diagnosis proved to be fulminating necrotizing amebic colitis with perforation. This case report serves as a reminder that amebiasis may occur in patients who have not been outside Canada, that it may readily be confused with other types of inflammatory bowel disease, and that particular care should be taken in obtaining a history of exposure. Before inflammatory bowel disease is diagnosed not only should the usual diagnostic tests such as stool examination and mucosal biopsy be done, but also serologic testing for amebiasis should be carried out.     

The acoustic repertoire of the Southern right whale,a quantitative analysis

Some 1274 southern right whale sounds were randomly selected and each sound was described by 10 acoustic variables. Two hundred and fifty of these sounds were also ‘labelled’ by the activity, size and sexual composition o the group producing them. Principal components analysis was performed on all the sounds' variables (1274×10) and on the variables for a subset of 823 sounds referred to as calls. Results of the principal components analyses indicate that the sounds can be divided into three major classes: blow sounds, slaps, and calls; and that the repertoire of calls is a continuum with certain types more common than others. The distribution of the ‘labelled’ sounds in the principal components analyses patterns revealed general associations between whale activities and the types of sounds produced.     

Determinants for cleavage of the chlorophyll a/b binding protein precursor: a requirement for a basic residue that is not universal for chloroplast imported proteins

We demonstrate that the precursor of the major light-harvesting chlorophyll a/b binding protein (LHCP of Photosystem II), encoded by a Type I gene, contains distinct determinants for processing at two sites during in vitro import into the chloroplast. Using precursors from both pea and wheat, it is shown that primary site processing, and release of a approximately 26-kD peptide, depends on an amino-proximal basic residue. Substitution of an arginine at position -4 resulted in an 80% reduction in processing, with the concomitant accumulation of a high molecular weight intermediate. Cleavage occurred normally when arginine was changed to lysine. The hypothesis that a basic residue is a general requirement for transit peptide removal was tested. We find that the precursors for the small subunit of Rubisco and Rubisco activase do not require a basic residue within seven amino acids of the cleavage site for maturation. In the wheat LHCP precursor, determinants for efficient cleavage at a secondary site were identified carboxy to the primary site, beyond what is traditionally called the transit peptide, within the sequence ala-lys-ala-lys (residues 38-41). Introduction of this sequence into the pea precursor, which has the residues thr-thr-lys-lys in the corresponding position, converted it to a substrate with an efficiently recognized secondary site. Our results indicate that two different forms of LHCP can be produced with distinct NH2-termini by selective cleavage of a single precursor polypeptide.     

Antiserum to a novel peptide sequence reacts selectively with epithelial subpopulations

A synthetic peptide corresponding to a novel protein sequence isolated from bovine kidney was used to immunize rabbits. When applied to Western blots of bovine kidney extracts, antiserum to this peptide recognizes proteins with molecular weights of 23 and 18 KD. Immunohistochemical examination of a variety of bovine and rat tissues with this antiserum revealed a unique distribution of immunoreactivity with the intermediate layers of a variety of stratified epithelia, in addition to renal glomeruli. The pattern of reactivity differed from previously described epithelial markers such as cytokeratins. These results indicate that this antiserum may be useful as a tool for the identification of cells of the intermediate layer of stratified epithelia and, as such, may aid in the study of this differentiating/proliferating tissue compartment.     

An embryo-specific protein of barley (Hordeum vulgare).

An immunological approach has been used to identify embryo-specific products that can be used as molecular markers of embryogenesis. Immunoadsorption of antisera to remove antigens common to embryos, meristematic cells and callus, revealed one major embryo-specific antigen, a polypeptide of 17 kDa. The antigen appeared at mid-stages of zygotic embryo formation and remained at similar levels up to six days post-germination of the seedling. The polypeptide could not be detected by protein staining, suggesting it is a non-abundant product. Appearance of the antigen could be induced by culture of zygotic embryos in vitro on abscisic acid (1 microM) or mannitol (9% mass/vol.). Cross-reactive products of near-identical molecular mass were observed in embryos of wheat, rye and oats but not distantly related cereals, nor embryos from dicotyledonous species. The timing of the appearance of the antigen was different in embryos formed from microspores during anther culture in vitro. In the cultured material, the 17-kDa polypeptide preceded the appearance of morphologically distinct embryonic structure.     

Binding of truncated peptides to the MHC molecule IA (d).

A peptide comprising amino acids 323-339 of chicken ovalbumin is known to bind to two heterodimeric conformations of the MHC molecule IA(d), and to each of its separate alpha- and beta-chains. We report that minor C- and N-terminal truncations of the parent peptide do not alter the binding pattern. A decrease in binding activity was observed upon deletion of the histidine residues of the already truncated peptides. Peptides as short as 4 amino acids associate weakly with all four proteins.     

Functional differentiation and primary metabolism of mouse mammary epithelial cells in extended-batch and hollow-fiber culture

Growth, expression of functional differentiation (as characterized by synthesis and secretion of milk proteins), and primary metabolism were studied for a mouse mammary epithelial cell line, COMMA-1D, in extended-batch and hollow-fiber reactor cultures. Batch cultures were performed on Costar polycarbonate membrane inserts, allowing basal and apical exposure to medium. Protein production was induced in both batch and hollow-fiber cultures in hormonesupplemented medium. In batch cultures, high levels of protein production and secretion were maintained for 18 days. Once differentiation was induced, the rate of deinduction was low, even in medium containing epidermal growth factor (EGF) and serum; cells continued to express and secrete proteins for at least 12 days after prolactin and hydrocortisone were removed. Cells in both batch and hollow-fiber cultures were highly glycolytic and exhibited low rates of glutaminolysis. In batch culture on membrane inserts, cells showed polarized metabolism between the apical and basal side, maintaining significant gradients of glucose and lactate. Medium hormonal composition and subsequent differentiation affected both glucose uptake and lactate yield for COMMA-1D in batch culture. (c) 1992 John Wiley & Sons, Inc.