Showing papers by "Rockefeller University published in 1970"

Embryonic vertebrate central nervous system: Revised terminology

Abstract: The layers and cells of the early developing central nervous system lack direct counterparts in the adult and must be designated by a special terminology. The inconsistent and inaccurate language now in use leads to misunderstanding and a revision is proposed in which the four fundamental zones are termed the ventricular, subventricular, intermediate, and marginal zones. Each is defined according to the form, behavior, and fate of its constituent cells. All neurons and macroglia of the central nervous system can be derived from these developmental zones.

Ontogeny of bird song.

Abstract: Fernando Nottebohm locomotion or feeding. Consequently, a study of vocal development involves control over only a small number of variables. This does not mean that the operation of the vocal system is free from constraints. The characteristics of its innervation (7), musculature (8), membranes and resonators (9) impose a limit on what can be done, and its functioning must incorporate the prior' ity of respiratory needs. Also, vocal patterns may be programmed by properties of the nervous system.

Multiple Antibiotic Resistance in a Bacterium with Suppressed Autolytic System

Abstract: Suppression of the activity of the cellular autolytic system of pneumococci causes simultaneous resistance against penicillin, D-cycloserine and phosphonomycin. This phenomenon represents a novel type of drug resistance mechanism in bacteria.

Controlled proteolysis of nascent polypeptides in rat liver cell fractions. I. Location of the polypeptides within ribosomes.

Abstract: Rough microsomes were incubated in an in vitro amino acid-incorporating system for labeling the nascent polypeptide chains on the membrane-bound ribosomes. Sucrose density gradient analysis showed that ribosomes did not detach from the membranes during incorporation in vitro. Trypsin and chymotrypsin treatment of microsomes at 0° led to the detachment of ribosomes from the membranes; furthermore, trypsin produced the dissociation of released, messenger RNA-free ribosomes into subunits. Electron microscopic observations indicated that the membranes remained as closed vesicles. In contrast to the situation with free polysomes, nascent chains contained in rough microsomes were extensively protected from proteolytic attach. By separating the microsomal membranes from the released subunits after proteolysis, it was found that nascent chains are split into two size classes of fragments when the ribosomes are detached. These were shown by column chromatography on Sephadex G-50 to be: (a) small (39 amino acid residues) ribosome-associated fragments and (b) a mixture of larger membrane-associated fragments excluded from the column. The small fragments correspond to the carboxy-terminal segments which are protected by the large subunits of free polysomes. The larger fragments associated with the microsomal membranes depend for their protection on membrane integrity. These fragments are completely digested if the microsomes are subjected to proteolysis in the presence of detergents. These results indicate that when the nascent polypeptides growing in the large subunits of membrane-bound ribosomes emerge from the ribosomes they enter directly into a close association with the microsomal membrane.

Subthreshold behavior and phenomenological impedance of the squid giant axon.

Abstract: The oscillatory behavior of the cephalopod giant axons in response to an applied current has been established by previous investigators. In the study reported here the relationship between the familiar "RC" electrotonic response and the oscillatory behavior is examined experimentally and shown to be dependent on the membrane potential. Computations based on the three-current system which was inferred from electrical measurements by Hodgkin and Huxley yield subthreshold responses in good agreement with experimental data. The point which is developed explicitly is that since the three currents, in general, have nonzero resting values and two currents, the "Na" system and the "K" system, are controlled by voltage-dependent time-variant conductances, the subthreshold behavior of the squid axon in the small-signal range can be looked upon as arising from phenomenological inductance or capacitance. The total phenomenological impedance as a function of membrane potential is derived by linearizing the empirically fitted equations which describe the time-variant conductances. At the resting potential the impedance consists of three structures in parallel, namely, two series RL elements and one series RC element. The true membrane capacitance acts in parallel with the phenomenological elements, to give a total impedance which is, in effect, a parallel R, L, C system with a "natural frequency" of oscillation. At relatively hyperpolarized levels the impedance "degenerates" to an RC system.

Fluids with Several Phase Transitions

Abstract: For a fluid in which the interaction potential has a hard core plus a negative part, softening of the hard core can produce a second transition if a first already exists. We give a general argument for the occurrence of the second transition in the lattice gas, plus explicit results for one-dimensional fluid models with two first-order transitions. One such model also provides an example of the breakdown of the law of rectilinear diameters.

Association of lactoferrin with specific granules in rabbit heterophil leukocytes

Abstract: Lactoferrin has been identified in rabbit heterophil leukocytes on the basis of its immunological reactivity, electrophoretic mobility, acid-resistant iron-binding properties, and spectral characteristics. Leukocyte lactoferrin was found to be exclusively localized in the specific (secondary) granules, which have been resolved from other subcellular components by zonal differential centrifugation and by isopycnic equilibration.

Structure and activity of acetylcholine.

Abstract: Conformational analysis of several agonists and antagonists can be used as a basis for the definition of structural parameters necessary for the range of activity of acetylcholine.

Morphology and peroxidase cytochemistry of mouse promonocytes, monocytes, and macrophages.

Abstract: Mouse promonocytes have been identified and studied in cultures of bone marrow cells. These cells have a diameter of 14–20 µ, and in stained preparations reveal a large, indented or folded nucleus, and basophilic, finely granular cytoplasm. The living promonocyte viewed by phase contrast shows additional features: nucleoli, small dense bodies, and vesicles in the cytoplasm adjacent to the nuclear hilus, and slight membrane ruffling. Prominent ultrastructural components of promonocytes include a well developed Golgi apparatus, small numbers of centrosomal granules and vacuoles, extensive ribosomal aggregates, and finger-like projections of the cell surface. Promonocytes engage in pinocytosis and phagocytosis, but they are less active in these functions than are peripheral blood monocytes of peritoneal macrophages. Promonocytes are positive for peroxidase, the reaction product being localized to granules most of which are centrally situated in the cell. Monocytes in blood or in inflammatory peritoneal exudates display much smaller numbers of peroxidase-positive granules, and various types of mature mouse macrophages are peroxidase negative.

The search for antibodies with molecular uniformity

Abstract: Publisher Summary This chapter discusses the physical, chemical, and biological aspects of γM antibodies in depth The chapter describes the physical characteristics, chemical composition, and subunit structure of the typical circular γM pentomers and the relationship of these molecules to low molecular weight γM-like proteins The characteristics of the interaction of γM antibodies with antigens—for example, the nature and number of antigen combining sites—and the interaction of γM antibodies with the complement system are compared to the corresponding properties of γG antibodies The biosynthesis and metabolism of γM antibodies and their peculiar role in the immune response are also discussed in the chapter The chapter presents a brief summary related to the hallmarks of immunoglobulin heterogeneity and the criteria that must be used to judge the restricted heterogeneity or molecular uniformity of an antibody preparation The chapter discusses human antibodies to certain selected antigens that appear to possess less heterogeneity than normal γ-globulin

Effects of Black Widow Spider Venom on the Frog Neuromuscular Junction: Effects on End-plate Potential, Miniature End-plate Potential and Nerve Terminal Spike

Abstract: Black widow spider venom causes exhaustion of miniature end-plate activity and depletes the nerve terminal of vesicles.

Vocal Imitation and Individual Recognition of Finch Calls

Abstract: American goldfinch females recognize individual males by their individually distinctive flight calls. Goldfinches and other cardueline finch species are also capable of learning new flight calls by imitation during pair and flock formation. Vocal imitation can occur between members of different species as well as between members of the same species. Learning of new flight calls differs in several respects from typical passerine song learning.

Selective Synthesis of a Nuclear Acidic Protein in Liver Cells stimulated by Cortisol

Abstract: Differential labelling experiments establish that synthesis of a non-histone protein of molecular weight 41,000 is specifically enhanced in response to the injection of cortisol into rats.

Selective retention of oestradiol by cell nuclei in specific brain regions of the ovariectomized rat.

Abstract: —Cell nuclei were isolated from four regions of the brains of ovariectomized female rats 2 hr after the injection of [3H]oestradiol. By light microscopy, the nuclear pellets contained highly purified nuclei of neuronal and glial cells with little cytoplasmic contamination. Tritium was concentrated in cell nuclei from the preoptic-hypothalamic area, to a lesser extent in nuclei from the amygdaloid region and hippocampus, and least of all in cerebral cortical nuclei. In comparison with whole homogenates (= 1-0), the nuclear concentrations of radioactivity were 12·9, 4·7, 1·9 and 0·8, respectively. Approximately 40 per cent of the radioactivity in homogenates of the preoptic-hypothalamic area was present in cell nuclei, and upon TLC more than 85 per cent of the radioactive material in the nuclei exhibited the RF of oestradiol-17β. Pretreatment of ovariectomized females with 1 mg of unlabelled oestradiol 30 min before the injection of labelled hormone abolished the nuclear uptake of [3H]oestradiol in all four regions of the brain. A concurrent injection of 10 μg of unlabelled oestradiol-17β significantly reduced nuclear uptake, while a similar injection of testosterone or oestradiol-17α had no significant effect. One mg of oestradiol-17α, but not testosterone, did reduce nuclear uptake. The retention of [3H]oestradiol by the preoptic-hypothalamic area decreased exponentially in the tissue from 30 min to 4 h after an intraperitoneal injection; however, nuclear binding reached a peak at 1-2 h and still showed high retention at 4 h. These results, together with observations in other laboratories of morphological changes induced by oestrogens, establish that certain regions of the brain are bona fide targets for the action of oestradiol.

Structure-function relationships in the adipose cell. I. Ultrastructure of the isolated adipose cell

Abstract: A method is described for preparing isolated rat adipose cells for electron microscopy. The ultrastructure of such cells and their production of 14CO2 from U-glucose-14C were studied simultaneously in the presence of insulin or epinephrine. Each adipose cell consists of a large lipid droplet surrounded by a thin rim of cytoplasm. In addition to typical subcellular organelles, a variety of small lipid droplets and an extensive system of membranes characterize the cell's cytoplasm. A fenestrated envelope surrounds the large, central lipid droplet. Similar envelopes surround cytoplasmic lipid droplets occurring individually or as aggregates of very small, amorphous droplets. Groups of individual droplets of smaller size also occur without envelopes. The system of membranes consists of invaginations of the cell membrane, vesicles possibly of pinocytic origin, simple and vesiculated vacuoles, vesicles deeper in the cytoplasm, flattened and vesicular smooth surfaced endoplasmic reticulum, and Golgi complexes. Neither insulin nor epinephrine produced detectable ultrastructural alterations even when cells were incubated under optimal conditions for the stimulation of 14CO2 evolution. Structural responses of the isolated adipose cell to hormones, if such occur, must, therefore, be dynamic rather than qualitative in nature; the extensive system of smooth surfaced membranes is suggestive of compartmentalized transport and metabolism.

In vitro induction of lysosomal enzymes by phagocytosis.

Abstract: The in vitro induction of lysosomal enzymes by phagocytosis was demonstrated in cultivated mouse peritoneal macrophages. The contribution of each of several steps in the endocytic process to enzyme induction was examined. The enzymatic response after the uptake of equal numbers of erythrocytes (RBC) and nondigestible particles were compared. Phagocytosis of RBC produced a marked increase in the levels of acid phosphatase, beta-glucuronidase, and cathepsin D. Puromycin (1 microg/ml) inhibited the enzyme response. In contrast, phagocytosis of polyvinyl toluene, polystyrene, and insoluble starch particles produced no increase in macrophage lysosomal enzymes, although fusion of phagosomes with preexisting lysosomes occurred normally. The endocytic stimulus to synthesis of inducible lysosomal enzymes, therefore, occurred at or beyond the stage of digestion. Purified protein (bovine gamma globulin) aggregates and homopolymer coacervates of poly-l-glutamic acid: poly-l-lysine were effective inducers of lysosomal acid phosphatase, beta-glucuronidase, and cathepsin D, whereas homopolymers of the same D-amino acids were ineffective as inducers. Both the quantity of phagocytized substrate and its rate of enzymatic hydrolysis appear to control the level and persistance of lysosomal hydrolases.

Frequency-specific relation between hippocampal theta rhythm, behavior, and amobarbital action.

Abstract: The frequency of the hippocampal theta rhythm in freely moving rats varies predictably in relation to behavior in a simple learning situation. The theta rhythm may be driven by electrical stimulation of the medial septal area at frequencies within the theta range. The threshold for septal driving is lowest at that frequency which the rat displays in response to frustrative nonreward; the driving threshold is selectively raised at this frequency by sodium amobarbital. It is suggested that the behavioral effects of amobarbital are due to a disruption of the theta frequency normally displayed in response to nonreward.

Somatic translocation of antibody genes.

Abstract: A review of the structural and genetic properties of the immunoglobulins suggests that somatic recombination is fundamental in the selective immune response.

Further biochemical and morphological studies of granule fractions from rabbit heterophil leukocytes

Abstract: Fractionation of rabbit heterophil leukocyte homogenates by isopycnic centrifugation as well as by zonal sedimentation has helped to characterize further the particulate components of these cells. Four classes have been identified: (A) Large (0.5–0.8 µm) and dense (1.26) azurophil or primary granules, containing all the myeloperoxidase, one-third of the lysozyme, and a major proportion of the lysosomal acid hydrolase activities of the cells. (B) Smaller (0.25–0.40 µm) and less dense (1.23) specific or secondary granules, containing 90% of the alkaline phosphatase and the remainder of the lysozyme activities, but very little if any acid hydrolases. (C) Particles of low density (1.20), containing the remainder of the lysosomal acid hydrolases. This fraction was heterogeneous, but showed abundant small rod- or dumbbell-shaped particles of moderate electron opacity, surrounded by a single membrane (tertiary granules?). The possible origin of these lysosomes from contaminating macrophages could not be ruled out but appeared unlikely. (D) Slowly sedimenting material of very low density (1.14), made up of large, empty vesicular membrane structures, and containing 10% of the alkaline phosphatase, and all of a thiol-dependent acid p-nitrophenyl phosphatase, an enzyme clearly different from the lysosomal acid phosphatase.