THE ENTERIC SURFACE COAT ON CAT INTESTINAL MICROVILLI

The enteric microvilli of the cat, bat, and man are coated with a conspicuous layer composed of fine filaments radiating from the outer dense leaflet of the plasma membrane. This surface coat is prominent on the absorptive cells but is not so thick on the goblet and undifferentiated crypt cells. In other species the surface coat is poorly developed or inconsistent, but all intestinal microvilli have traces of such a coating over the tips and sides of the microvilli. Tissues prepared by the ordinary sectioning techniques for electron microscopy usually reveal this component when stained with uranyl acetate followed by lead staining. The surface coat is intensely periodic acid-Schiff (PAS) positive and reacts with Alcian blue or Hale's colloidal iron stain for acid mucopolysaccharide. It is also stained by toluidine blue at low pH. Repeated washings or incubation with various chemical agents have failed to remove or markedly alter the appearance of the coating, but extruded cells undergoing autolysis lose their surface coats. The stability, consistent presence, and intimate association of the mucopolysaccharide coat suggest that it may be an integral part of the plasmalemma rather than an "extraneous coat."     

Experimental Salmonellosis XI. Induction of Cellular Immunity and Formation of Antibody by Transfer Agent of Mouse Mononuclear Phagocytes

When mice were injected intraperitoneally with a ribonucleic acid (RNA) preparation extracted from the peritoneal mononuclear phagocytes (termed monocytes) of immunized mice, these macrophages developed cellular immunity and cellular antibodies. The peritoneal monocytes were obtained from normal mice and maintained in tissue culture bottles in a homogeneous cell population. When they were treated in vitro with an immune RNA preparation, they acquired cellular immunity, and cellular antibodies were detectable in such monocytes. These results suggest that the mononuclear phagocytic cell line constitutes a cell line responsible for antibody formation.     

Brom Cresol Green and Brom Phenol Blue as Indicators of Respiration Deficiency in Yeast

Strains of Saccharomyces which contained cells of respirationally normal (wild-type) and of respiration-deficient (RD) mutants were grown on untrient agar plates containing 20-23 mg/liter of either brom cresol green (BCG) or brom phenol blue (BPB). Glucose content of the media was varied experimentally in the range of 1.5-6%. After 2-4 days of incubation, normal colonies were very palely stained whereas RD colonies were drak green with BCG and dark blue with BPB. Optimum glucose content in the medium was 2-3% for S. cerevisiae, S. carlbergensis and S. chevalieri, but Fleischmann's (baker's) yeast developed the best color contrast with 4-5% glucose.     

Improved Assay Method for Phospholipase C

A lecithin sol dispersed with deoxycholate was found to be attacked by phospholipase C in the presence of calcium ion more rapidly than were any other lecithin sols. The inorganic phosphate could be released quantitatively from the acid soluble phosphate liberated from lecithin by an excess amount of alkaline phosphatase present in phospholipase C reaction mixture. A simple and accurate assay method for phospholipase C was developed with the sol and the alkaline phosphatase.     

Diploid-tetraploid relationship among old-world members of the fish family Cyprinidae

Evidence suggesting that the goldfish and the carp of the family Cyprinidae are tetraploid species in relation to other members of the same family were presented. The two barb species, Barbus tetrazona and Barbus jasciatus, were chosen as representatives of diploid members of the family Cyprinidae. These barbs had the diploid chromosome number of 50 and 52 and the DNA value 20–22% that of placental mammals, while the goldfish (Carassius auratus) and the carp (Cyprinus carpio) had the diploid chromosome number of about 104 and the DNA value 50–52% that of placental mammals.Supported in part by a grant (CA-05138) from the National Cancer Institute, U.S.Public Health Service, and in part by a research fund established in honor of General James H. Doolittle at Duarte, and by the British Empire Cancer Campaign for Research at Northwood. Contribution No. 11-67, Department of Biology, City of Hope Medical Center. Dr. Junichi Muramoto is a fellow of the Institute for Advanced Learning of the City of Hope Medical Center.     

Comparative DNA values and chromosome complements of eight species of fishes

The present study appears to indicate that a series of polyploidization of the original vertebrate genome took place while vertebrates were still aquatic forms. The polyphyletic evolution of terrestrial vertebrates is suggested. The lung fish revealed close kinship to present-day members of the order Caudata of the class Amphibia. The DNA value was 3,540 per cent that of mammals. The trout had the DNA value similar to that of mammals and also to that of members of the orders Crocodylia and Chelonia of the class Reptilia. The DNA value of the gold fish, on the other hand, was very similar to that of birds and of snakes and lizards as well. It was 50 per cent that of mammals. Flat fishes and the swordtail had the undistinguished diploid complement made of 48 acrocentrics and the lowest DNA value merely 20 per cent that of mammals. They were regarded as the retainers of the original vertebrate genome.In Northwood, this work was supported by the British Empire Cancer Campaign. In Duarte, this work was supported in part by grant CA-05138 from the National Cancer Institute, U.S. Public Health Service. Contribution No. 56-65, Department of Biology.     

The cell cycle regulator, human p50weel, is a tyrosine kinase and not a serine/tyrosine kinase.

The human weel protein, a homologue of the yeast weel protein, was expressed in E. coli and purified to homogeneity. The purified weel protein phosphorylated the tyrosine residue of cdc2 kinase in HeLa cell extracts in the presence of human cyclin B1. It also phosphorylated the tyrosine but not the threonine residue in the peptide of the amino-terminal of cdc2 kinase, although both these residues have been shown to be phosphorylated in higher eukaryotes in vivo. Furthermore, serine and tyrosine residues of the yeast weel protein are reportedly autophosphorylated in vitro, however the tyrosine residue of the human weel protein was autophosphorylated whereas the serine and threonine residues were not. These data indicate that human p50weel is tyrosine kinase and that it phosphorylated the tyrosine residue of the amino-terminal of cdc2 kinase in the presence of cyclin B1 and that the threonine residue is phosphorylated by another, unknown kinase.