The murine sublingual and submandibular mucins. Their isolation and characterization.

From the mouse sublingual and submandibular glands high-molecular weight glycoproteins (mucins) were isolated. These mucins appeared to be homogeneous in polyacrylamide gel electrophoresis and in the analytical ultracentrifuge. S20,W values of 10.9 and 5.5 were found for the sublingual and submandibular mucin respectively. With sodium dodecyl sulfate or N-acetylcysteine no subunits could be detected. Both mucins consisted for about 1/3 of protein and 2/3 carbohydrate. Their mucin character was also denoted by the high content of serine plus threonine. Respectively 42 mol% and 34 mol% of the protein core of the sublingual and submandibular mucins consisted of these amino acids. The main sugars in these mucins were sialic acid, galactosamine, galactose, glucosamine and mannose. The molar ratio for the sublingual and submandibular mucin being 1.00 : 1.03 : 1.08 : 0.26 : 0.23 and 1.00 : 0.71 : 1.10 : 0.65 : 0.53, respectively. The sialic acid content of both mucins was about 25%. Fucose and sulfate, on the other hand, were less than 1%. The presence of sulfate was also indicated by preliminary studies in vivo on the incorporation of [35SO4] sulfate.     

The surface potential of and double-layer interaction force between surfaces characterized by multiple ionizable groups.

At the beginning of cleavage, a cell develops the form of a short central cylinder capped at the ends with ellipsoids. The strain pattern produced by this shape, with the application of constricting forces, guides the cell either to divide into two spherical cells or to take the shape of a long, thin cell which may remain a single cell or divide into two thin cells.     

The centrifugal horizontal cells in the lobula plate of the blowfly, Phaenicia sericata

Intracellular recordings combined with iontophoretic injection of Procion Yellow M4RAN were used to study the anatomy and physiology of the centrifugal horizontal cells (CH-cells) in the lobula plate of the blowfly, Phaenicia sericata.Anatomy: The CH-cells comprise a set of two homolateral, giant visual interneurones (DCH, VCH) at the rostral surface of each lobula plate. Their extensive arborizations in the lobula plate possess bulbous swellings (boutons terminaux). The arborization of one cell (DCH) covers the dorsal, and the arborization of the other cell (VCH) the ventral half of the lobula plate. Their axons run jointly with those of the horizontal cells through the chiasma internum and the optic peduncle. Their protocerebral arborization possesses spines; they form a dense network together with the axonal arborization of the horizontal cells, a second type of giant homolateral cell most sensitive to horizontal motion. The protocerebral arborization of the CH-cells gives rise to a cell body fibre which traverses the protocerebrum dorsally to the oesophageal canal. The cell body lies on the contralateral side laterally and slightly dorsally to the oesophageal canal in the frontal cell body layer.Physiology: The CH-cells respond with graded potentials to rotatory movements of their surround. Cells in the right lobula plate respond with excitation (excitatory postsynaptic potentials, membrane depolarization) to clockwise motion (contralateral regressive, ipsilateral progressive), and with inhibition (inhibitory postsynaptic potentials, membrane hyperpolarization) to counterclockwise motion in either or both receptive fields; CH-cells respond to motion presented to the ipsilateral and/or contralateral eye. Cells of the left lobula plate respond correspondingly to the reverse directions of motion. Vertical pattern motion and stationary patterns are ineffective.The heterolateral H1-neurone elicits excitatory postsynaptic potentials in the DCH-cell; these postsynaptic potentials are tightly correlated 1:1 to the preceding H1-action potentíal. The delay between the peak of the action potential and the beginning of the DCH-postsynaptic potential is 1.15 msec, agreeing very well with the value reported previously for the blowfly, Calliphora (Hausen, 1976a). The synaptic input and output connections of the CH-cells are discussed.     

The structure of steady-state enzyme kinetic equations: a graph-theoretical algorithm for obtaining conditions for reduction in degree by common-factor cancellation

Many enzyme kinetic steady-state equations are so complicated that analysis of their predictions, preferably by graph-theoretical methods, without deriving the equations is desirable. An example of such a method is given here. It is a graph-theoretical algorithm for determining non-trivial relations between the rate constants of a mechanism that cause the numerator and denominator of its rate expression have a common factor so permitting the degree of the expression to be reduced. An algorithm for writing the several different forms of the reduced rate equation is also given. The algorithm is applied to some standard simple enzymic mechanisms that give relatively complicated rate equations.In the case of a 2:2 equation, the sign of curvature in a double reciprocal plot depends on the sign of the expression in the common-factor condition.     

An evaluation of the mutagenic, carcinogenic and teratogenic potential of microwaves

A notable proportion of the population is exposed to an increasing number of devices emitting microwaves, a form of non-ionizing electromagnetic radiation in the range 300-30000 mHz. The activation energy of microwave radiations is too small to directly modify any chemical bonds in the irradiated matter. At microwave frequencies the macroscopic dielectric properties of tissues are strongly determined by their water content. Tissues like muscle, brain, skin, with a high water content, have higher permittivity and conductivity values than bone or fat with low water contents. Owing to the energy transfer, to living tissues, by a dipolar relaxation mechanism of water molecules, the penetration of microwaves is limited and one observes a fast and very efficient heat-loss production. A review of the available literature shows that most results on the mutagenicity of microwaves are negative or can often be explained by a temperature enhancement. If microwaves are apparently unable to damage DNA at sub-thermal exposure levels, some results indicate, however, that they might easily potentiate the damaging action of other DNA antagonist agents such as UV or chemicals.     

Egg-laying behaviour and nest-site selection of domestic hens kept in small floor-pens

The development of egg-laying behaviour and nest-site choice is described in seven flocks of White Leghorn hens housed in small floor-pens. Special interest was directed towards social dominance and the effect of the presence of a cock on the hen's nest-site choice. In the weeks before the hens came into lay, they frequently examined the nests. Nest-entries only occurred some days before, or in the hours preceding, the first oviposition. Some hens were very conservative in their nest-site choice within clutches as well as between clutches. A number of hens only persevered in their nest-site choice within clutches, while a third category did not show any consistency in their choices. Individual hens were consistent in using either the floor or a nest-box as a nesting site.No relationship was found between social status and nest-site choice, nor between social status and floor-laying. Some evidence was provided that the presence of a cock could reduce the number of floor-eggs in a flock provided with roll-away boxes.It is postulated that the nest-examinations in the weeks before laying may serve for the selection of a suitable nest-site.     

Discussion on the state of water in the myofilament lattice and other biological systems, based on the fact that the usual concepts of colloid stability can not explain the stability of the myofilament lattice

Application of the usual concepts of colloid stability shows that the in vivo spacings between the myofilaments, making up the contractile part of the muscle myofibrils, correspond to energies of 10(-4) to 10(-1) kT. Refinements in the calculations of the electrostatic and Van der Waals-London energies do not significantly modify these values. Therefore, theory does not predict the observed stability of the myofilament lattice. It is shown that the interfilament water very likely plays an active role in the myofilament lattice. More generally, the structure of water in living cells is probably different from that of bulk water.     

Characterization of a rat yolk sac carcinoma cell line

A continuous cell line was established from an experimentally induced rat yolk sac carcinoma. In the early passages both visceral and parietal yolk sac carcinoma were present (designated L1). When the cell line was reestablished in culture after serial transplantations in rats, only parietal yolk sac carcinoma could be identified (designated L2). This cell line expresses parietal yolk sac endoderm characteristics in that it synthesizes basement membrane components, in particular, laminin, but also entactin, collagen IV, and heparan sulfate proteoglycan. In addition, a noncartilage chondrotin sulfate proteoglycan is synthesized. This rat yolk sac carcinoma cell line L2 will be a valuable model for the study of basement membrane components.     

On Zeeman's equations for the nerve impulse

A model for the nerve impulse due to Zeeman (1972) and based on catastrophe theory is compared with alternative models and criticisms of Zeeman's model by Sussmann and Zahler (1977, 1978) are assessed. The criticisms of Zeeman's motivation for his model are found to carry some weight. Sussmann and Zahler (1977, 1978) list numerous features of Zeeman's model which, they state, are not in agreement with experiment. These statements as they stand are largely erroneous, and the model still remains to be tested by a critical series of experiments. However, a detailed analysis reveals defects in Zeeman's model, not among those claimed by Sussmann and Zahler, showing that the explicit equations of the model cannot be correct. The possibility of a modified approach along similar lines and its ultimate adoption remains open.     

Fiber optic mapping of the Xenopus visual system: shift in the retinotectal projection during development

Two new techniques for assaying the retina to tectum connections in the lower vertebrate visual system are presented. These techniques allow defined regions of the retina to be stimulated, thus circumventing some of the difficulties of the more conventional retinotectal mapping techniques. Applying these techniques to the Xenopus visual system demonstrates that the retina-to-tectum projection shifts during development. The central part of the retinotectal projection moves medially and caudally about 150 microns (10% of the size of the tectum) in two weeks. The presence of such plasticity in a normal developing animal indicates that the plasticity previously observed in experimentally altered animals probably reflects a normal developmental process.     

Local energized proton hypotheses of mitochondrial oxidative phosphorylation

Two hypotheses are compared each interpreting mitochondrial energy transduction in terms of a localized form of proton activity. Their differences are seen to be profound and far-reaching. It is concluded that the "chemiosmotic/local energized proton dialogue" as conducted hitherto has offered a very incomplete and restricted analysis of the problems of mitochondrial oxidative phosphorylation.     

Role of cytoplasmic proteins in cold shock injury of Amoeba

Strains of Amoeba have been used to study the mechanisms of cellular injury induced by rapid cooling (cold shock). Cell viability was found to depend on the time and temperature of cold exposure, on the rate of cooling and on the morphology of the cells prior to chilling. All strains underwent a granuloplasmic contraction following undercooling to ?10 °C, although its extent varied; strains most damaged by cold shock exhibited the most violent cytoplasmic contractions. Cryomicroscopy demonstrated that the cellular contraction occurred upon rewarming, not during cooling. Cells damaged by cold shock were osmotically responsive, demonstrating that irreversible damage to the plasmalemma does not account for the phenomenon.Several compounds protected Amoeba against cold shock injury, glycerol and glucose being the most effective. With glycerol an optimum rate of cooling was observed upon cooling to ?10 °C, at both faster and slower cooling rates damage increased.The state of cellular actin in control cells and following cold shock was monitored by the DNase 1 inhibition assay and by electron microscopy. A comparatively “cold shock resistant” strain of A. proteus was found to contain less total actin per unit cellular protein than the more “sensitive” Amoeba sp. strain Bor. In the Bor strain a cold-induced aggregation of cytoplasmic filaments was evident in electron micrographs, presumably a crosslinking of preexisting F-actin.     

Biosynthesis of cyclopiazonic acids in Penicillium cyclopium: The isolation of dimethylallylpyrophosphate: Cyclo-acetoacetyltryptophanyl dimethylallyltransferase

During the production of β-cyclopiazonic acid (βCA) by Penicillium cyclopium, the following points are noted: (a) Dimethylallylpyrophosphate (DMAPP), which is incorporated into α-cyclopiazonic acid (αCA) in vivo, stimulates overall CA synthesis, whereas tryptophan, although incorporated into αCA, inhibits overall CA synthesis. (b) A previously suggested substrate, γ,γ-dimethylallyltryptophan, is not a precursor of αCA. (c) The accumulation of cyclo-acetoacetyl-l-tryptophanyl (cAATrp) is described in both the culture medium and mycelium with increasing growth. (d) A cell-free extract of mycelium will catalyze the conversion of exogenous cAATrp and exogenous DMAPP into βCA in 1:1 stoichiometry, the βCA being bound to a protein.     

Dictyostelium calmodulin: affinity isolation and characterization

The Ca2+-binding regulatory protein calmodulin (CaM) has been purified from the cellular slime mold, Dictyostelium discoideum. Isolation of homogeneous Dictyostelium CaM was accomplished in high yield by ion-exchange chromatography and Ca2+-dependent affinity chromatography on phenothiazine-Sepharose 4B. This isolate has been demonstrated to possess the following physicochemical and functional properties characteristic of other CaM isolates: (i) a molecular weight ca. 16,000; (ii) an amino acid composition similar to other CaMs--with the notable exception that Dictyostelium CaM, as first determined by Bazari and Clarke [(1981) J. Biol. Chem. 256, 3598-3603] lacks the single trimethylated lysine (Tml) residue identified in nearly all CaMs purified to date; (iii) a CNBr peptide map similar to that of other CaMs; (iv) a Ca2+-dependent shift in migration during native- and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses; (v) ability to form Ca2+-dependent complexes with rabbit skeletal muscle troponin I; and (vi) ability to activate in a Ca2+-dependent manner bovine brain cyclic nucleotide phosphodiesterase.     

Microtubule arrays in the cortex and near the germinal vesicle of immature starfish oocytes

An extensive array of long, crisscrossing microtubules has been discovered in the cortex of oocytes of the starfish Pisaster ochraceus. The microtubules were visualized in cortex preparations by indirect immunofluorescence microscopy using antibodies to tubulin. The cortical array of microtubules is present in all oocytes before and for about 30 min after the application of 1-methyladenine, the hormone that induces oocyte maturation. The presence of microtubules was confirmed by electron microscopy. The microtubules in this array are depolymerized when oocytes are treated with colchicine or nocodozole and are augmented when oocytes are treated with taxol. Dihydrocytochalasin B treatment of the oocytes causes the microtubules to aggregate, presumably by altering a microfilament network also found in the cortex. The distribution of microtubules was also explored in whole oocytes stained with antitubulin. One or two aster-like structures were observed adjacent to the germinal vesicle of each oocyte.     

Ecology of cryptic coral reef communities. IV. Community development and life histories of encrusting cheilostome bryozoa

Life histories of encrusting cheilostome species from the cryptic reef community at Rio Bueno, Jamaica, were studied on fouling panels over 3 yr. Recruitment and growth were generally slow compared with those reported for temperate cheilostomes. Most species that became abundant and persisted throughout the study did so through relatively rapid growth to a large size by a few successful colonies, rather than by accumulating great numbers of small colonies. This pattern, which reflects a striking increase in maximum survival with increasing colony size, is the basis for the extremely patchy distributions of bryozoans under corals. Reproduction in these species is delayed, and only a few long-lived, large colonies ever reproduce. Only one species, Drepanophora tuberculatum (Osburn), approached the characteristic opportunistic pattern of high recruitment, small colony size, and early reproduction.Grazing and nesting activities of one yellowtail damselfish greatly affected distributions of major taxa and cheilostome species on one set of panels. Species more abundant on grazed panels are more heavily calcified and showed other protective features, compared with species more abundant elsewhere. Despite intensive grazing by the fish, overgrowth interactions occurred frequently on both sets of panels. The fish affected what organisms were present, but did not obviously reduce the amount of overgrowth.