Showing papers by "Rockefeller University published in 1969"
708 citations
TL;DR: Two procedures for isolating 80 to 85% of the total hexuronic acid from bovine nasal cartilage as proteinpolysaccharide complex are described and compared, and it is suggested that disaggregation is fundamental to the extraction process.
598 citations
TL;DR: Reduction and alkylation of isolated proteoglycan subunit and of the glycoprotein fraction suggest that disulfide bonds in both are required for aggregation, but that those in the former are more sensitive to reduction.
570 citations
TL;DR: The size, number, and rate of formation of mature adipocytes were studied in the epididymal pads and retroperitoneal adipose depots of the Sprague-Dawley rat and the concept of a fixed number of maturity adipocytes in the adult organism may be of central importance in caloric and metabolic equilibrium.
385 citations
TL;DR: It is concluded that, in the blood capillaries of the inintestinal mucosa, the diaphragms of the endothelial fenestrae contain the structural equivalents of the small pore system.
Abstract: Horseradish peroxidase (mol. diam. ≃50 A) and ferritin (mol. diam. ≃110 A) were used as probe molecules for the small and large pore system, respectively, in blood capillaries of the intestinal mucosa of the mouse. Peroxidase distribution was followed in time, after intravenous injection, by applying the Graham-Karnovsky histochemical procedure to aldehyde-fixed specimens. The tracer was found to leave the plasma rapidly and to reach the pericapillary spaces 1 min post injection. Between 1 min and 1 min 30 sec, gradients of peroxidase reaction product could be demonstrated regularly around the capillaries; their highs were located opposite the fenestrated parts of the endothelium. These gradients were replaced by even distribution past 1 min 30 sec. Ferritin, followed directly by electron microscopy, appeared in the pericapillary spaces 3–4 min after i.v. injection. Like peroxidase, it initially produced transient gradients with highs opposite the fenestrated parts of the endothelium. For both tracers, there was no evidence of movement through intercellular junctions, and transport by plasmalemmal vesicles appeared less efficient than outflow through fenestrae. It is concluded that, in the blood capillaries of the inintestinal mucosa, the diaphragms of the endothelial fenestrae contain the structural equivalents of the small pore system. The large pore system seems to be restricted to a fraction of the fenestral population which presumably consists of diaphragm-free or diaphragm-deficient units.
361 citations
TL;DR: The lysosomes were found to have the ability to dephosphorylate phosphatidic acid, α-glycerophosphate, and, although rather slowly, the phosphomonoesters of choline, ethanolamine, and serine, which are clear to accomplish the important digestive functions with which they are credited.
352 citations
TL;DR: The relevance of hormone retention to the function of the hippocampus and septum in behavior and control of ACTH release is discussed and the possible cellular sites of action of corticosterone are considered.
309 citations
TL;DR: It has been suggested that song may subserve territorial advertisement, attracting unmated females and repelling other males and that it may affect other aspects of the integration of breeding behavior.
Abstract: Any intelligent statement about the role of dialects in bird song presupposes a knowledge of the functions of song. It has been suggested that song may subserve territorial advertisement, attracting unmated females and repelling other males. Less speculation has attended the possibility that song may stimulate the female to undergo hormonal changes leading towards ovulation or that it may affect other aspects of the integration of breeding behavior.
305 citations
TL;DR: Estimates of daily synthesis of cholesterol in man are estimated by measuring the excretion of cholesterol and its conversion products during periods of controlled sterol intake (sterol balance method), using isotopic or chromatographic procedures (or a combination of the two).
302 citations
TL;DR: Postnuclear supernates from homogenates of essentially pure rabbit heterophil leukocytes were fractionated by means of zonal differential centrifugation through a discontinuous sucrose gradient at various speeds and three distinct groups of granules were characterized biochemically and morphologically.
Abstract: Postnuclear supernates from homogenates of essentially pure rabbit heterophil leukocytes were fractionated by means of zonal differential centrifugation through a discontinuous sucrose gradient at various speeds. Three distinct groups of granules were characterized biochemically and morphologically. They were, in order of decreasing sedimentation coefficient: (a) Large, relatively dense granules, identified morphologically as the azurophil or primary granules, and containing essentially all of the myeloperoxidase activity of the preparations, about one-third of their lysozyme activity, and between 50 and 80% of their content in five acid hydrolases typically associated with lysosomes in other cells; (b) smaller, less dense granules, with the morphological appearance of the specific or secondary granules, and carrying most of the alkaline phosphatase and the remainder of the lysozyme activity of the preparations; (c) a second group of lysosome-like particles, associated with a morphologically heterogeneous fraction, and containing the remainder of the acid hydrolases, but little or no myeloperoxidase. When p-nitrophenyl phosphate was used instead of beta-glycerophosphate for the assay of acid phosphatase, only small proportions of the total activity accompanied the two main lysosomal bands, and considerable activity was found in a zone slightly retarded with respect to the slowly moving band of acid hydrolases.
287 citations
TL;DR: The method of sorting is used to study how lexical information might be organized and stored in memory and an argument is made that the conceptual features used by most judges derive from presuppositions and assertions contained in the definitions of the nouns.
TL;DR: It is demonstrated that feedback control by dietary cholesterol does occur in man and there are important differences between man and various laboratory animals in regard to the interaction of absorption and synthesis as factors controlling the size of tissue pools of cholesterol.
TL;DR: The data strongly support the hypothesis that two systems of electric current exist in the membranes of Limulus as the sum of a dark current and a light-induced current.
Abstract: In the dark, the ventral photoreceptor of Limulus exhibits time-variant currents under voltage-clamp conditions; that is, if the membrane potential of the cell is clamped to a depolarized value there is an initial large outward current which slowly declines to a steady level. The current-voltage relation of the cell in the dark is nonlinear. The only ion tested which has any effect on the current-voltage relation is potassium; high potassium shifts the reversal potential towards zero and introduces a negative slope-conductance region. When the cell is illuminated under voltage-clamp conditions, an additional current, the light-induced current, flows across the cell membrane. The time course of this current mimics the time course of the light response (receptor potential) in the unclamped cell; namely, an initial transient phase is followed by a steady-state phase. The amplitude of the peak transient current can be as large as 60 times the amplitude of the steady-state current, while in the unclamped cell the amplitude of the peak transient voltage never exceeds 4 times the amplitude of the steady-state voltage. The current-voltage relations of the additional light-induced current obtained for different instants of time are also nonlinear, but differ from the current-voltage relations of the dark current. The ions tested which have the greatest effect on the light-induced current are sodium and calcium; low sodium decreases the current, while low calcium increases the current. The data strongly support the hypothesis that two systems of electric current exist in the membrane. Thus the total ionic current which flows in the membrane is accounted for as the sum of a dark current and a light-induced current.
TL;DR: Adenovirus type 12 infects baby hamster kidney cells (BHK21), but does not multiply in these cells, and replication of Ad 12 DNA cannot be detected by equilibrium sedimentation in CsCl density gradients or by DNA-DNA hybridization on membrane filters.
TL;DR: Ferritin-conjugated, type-specific antibodies localize on homologous M+ cells in a pattern suggestive of several M antigenic sites along the length of individual surface fimbria, suggesting the following hypothesis: M antigen is secreted by the cell, is partially excreted through the otherwise intact cell wall, and is bound by the wall so that M protein occupies a peripheral, exposed position on the surfaces of the streptococcal cell wall.
Abstract: The presence of M antigens on group A streptococci is associated with hairlike fimbriae that cover the surface of the streptococcal cell wall and are demonstrable by electron microscopy. These fimbriae also may be associated with R antigen. Like M protein, the surface fimbriae are destroyed by trypsin treatment and reappear when "trypsinized" streptococci are reincubated in fresh, trypsin-free broth.
Ferritin-conjugated, type-specific antibodies localize on homologous M+ cells in a pattern suggestive of several M antigenic sites along the length of individual surface fimbria. The M-associated fimbriae remain on the residual cell wall after removal of the bulk of group-specific polysaccharide through nitrous acid extraction. This suggests attachment of the fimbriae to the mucopeptide and minor polysaccharide components remaining in the nitrous acid-extracted wall.
The pattern of localization of ferritin-conjugated antibodies on homologous streptococci before and after trypsin exposure and upon reincubation of the trypsinized cells in fresh medium suggests the following hypothesis: M antigen is secreted by the cell, is partially excreted through the otherwise intact cell wall, and is bound by the wall so that M protein occupies a peripheral, exposed position on the surfaces of the streptococcal cell wall.
TL;DR: Reductions in both expulsion and removal rates of TCu because of medical reasons constituted the principal factors accounting for the continuation rate of 77.6 as compared with 65.6 for loop D at the end of 2 years of use.
TL;DR: The findings indicate that the rates of synthesis and degradation of the NADPH-cytochrome c reductase vary conversely in the induction process, and the relevance of these findings to the control of the turnover of membrane enzymes is discussed.
TL;DR: The work reported in this monograph has clearly established the presence of peroxisome-like particles in lower and higher representatives of both major biological kingdoms, and invites speculation on the phylogenetic history of these particles.
Abstract: The work reported in this monograph has clearly established the presence of peroxisome-like particles in lower and higher representatives of both major biological kingdoms. Such findings invite speculation on the phylogenetic history of these particles, especially since some of the characters of peroxisomes label them as “primitive”, in both the literal and the figurative sense of the word. Some thoughts on the origin and evolutionary fate of peroxisomes were set forth briefly in earlier publications.4,5J0 They will be developed in a more systematic fashion in the present paper, in the hope that they may contribute to our understanding of the biological significance of peroxisomes, and perhaps provide some sort of guide for fruitful experimentation.
TL;DR: Morphologic and metabolic changes occurring in the retinal ganglion cells of goldfish after optic tract section and during the regeneration of new axons are described and it is concluded that the morphologic changes are indicative of an increased rate of protein synthesis by cells which are actively regenerating new axon.
TL;DR: The availability of a method for preparation of intact bile canaliculi should prove useful for studying the biochemical events associated with the transport of bile constituents into Canaliculi.
Abstract: A method is described for the rapid isolation of a plasma membrane fraction containing a high concentration of intact bile canaliculi from the rat liver. Isolated bile canaliculi retain most of the ultrastructural features exhibited in the intact liver cell. The final fraction contains 5'-nucleotidase activity at approximately the same concentration as that in previous preparations of plasma membranes. In the presence of 0.01 M Mg++, 5'-nucleotidase exhibits a double pH optimum at pH values of 7.5 and 9.5. The activities of glucose-6-phosphatase and alkaline phosphatase are present in low amounts. Cytochrome P-450 is not detectable. Na+-K+-activation of ATPase is observed to the extent of 20–36% in about half of the assays. The availability of a method for preparation of intact bile canaliculi should prove useful for studying the biochemical events associated with the transport of bile constituents into canaliculi.
TL;DR: The tryptophan hydroxylase activity in the rat midbrain decreases after adrenalectomy and is restored by treatment with cortic testosterone, an indication that the enzyme has a rapid turnover even in the absence of corticosterone.
Abstract: The tryptophan hydroxylase activity in the rat midbrain decreases after adrenalectomy and is restored by treatment with corticosterone. Cycloheximide, adminiistered intracisternally, prevents the restoration of the enzyme activity by corticosterone. Cycloheximide administration to adrenalectomized rats resutlts in a further decrease in the enzyme activity. an indication that the enzyme has a rapid turnover even in the absence of corticosterone.
TL;DR: The ventral photoreceptor cell has many properties in common with a variety of retinular cells and therefore should serve as a convenient model of the primary receptor cell in many invertebrate eyes.
Abstract: The ventral photoreceptors of Limulus polyphemus are unipolar cells with large, ellipsoidal somas located long both "lateral olfactory nerves." As a consequence of their size and location, the cells are easily impaled with microelectrodes. The cells have an average resting potential of -48 mv. The resting potential is a function of the external concentration of K. When the cell is illuminated, it gives rise to the typical "receptor potential" seen in most invertebrate photoreceptors which consists of a transient phase followed by a maintained phase of depolarization. The amplitude of the transient phase depends on both the state of adaptation of the cell and the intensity of the illumination, while the amplitude of the maintained phase depends only on the intensity of the illumination. The over-all size of the receptor potential depends on the external concentration of Na, e.g. in sodium-free seawater the receptor potential is markedly reduced, but not abolished. On the other hand lowering the Ca concentration produces a marked enhancement of both components of the response, but predominantly of the steady-state component. Slow potential fluctuations are seen in the dark-adapted cell when it is illuminated with a low intensity light. A spike-like regenerative process can be evoked by either the receptor potential or a current applied via a microelectrode. No evidence of impulse activity has been found in the axons of these cells. The ventral photoreceptor cell has many properties in common with a variety of retinular cells and therefore should serve as a convenient model of the primary receptor cell in many invertebrate eyes.
TL;DR: The hypothesis that during the maturation of the virion by budding from the cell surface, the lipids of the plasma membrane are incorporated quantitatively into the viral envelope is supported.
TL;DR: Rat liver peroxisomes isolated by density gradient centrifugation were disrupted at pH 9, and subdivided into a soluble fraction containing 90% of their total proteins and virtually all of their catalase, D-amino acid oxidase, L-α-hydroxy acid oxidases and isocitrate dehydrogenase activities, and a core fraction containing urate oxidase and 10% of the total proteins.
Abstract: Rat liver peroxisomes isolated by density gradient centrifugation were disrupted at pH 9, and subdivided into a soluble fraction containing 90% of their total proteins and virtually all of their catalase, D-amino acid oxidase, L-α-hydroxy acid oxidase and isocitrate dehydrogenase activities, and a core fraction containing urate oxidase and 10% of the total proteins. The soluble proteins were chromatographed on Sephadex G-200, diethylaminoethyl (DEAE)-cellulose, hydroxylapatite, and sulfoethyl (SE)-Sephadex. None of these methods provided complete separation of the protein components, but these could be distributed into peaks in which the specific activities of different enzymes were substantially increased. Catalase, D-amino acid oxidase, and L-α-hydroxy acid oxidase contribute a maximum of 16, 2, and 4%, respectively, of the protein of the peroxisome. The contribution of isocitrate dehydrogenase could be as much as 25%, but is probably much less. After dissolution of the cores at pH 11 , no separation between their urate oxidase activity and their protein was achieved by Sephadex G-200 chromatography.
TL;DR: After the optic tract was cut in goldfish, transport of protein in the intact optic nerve segment attached to the eye was increased and the rate remained elevated for several weeks after the optic fibers had connected with the tectum.
TL;DR: The exposure of cultivated mouse macrophages to sucrose leads to the formation of large phase- and electron-lucent, acid phosphatase-positive vacuoles in the perinuclear region, and the uptake of sucrose by pinocytosis and its subsequent segregation and storage in secondary lysosomes are suggested.
Abstract: The exposure of cultivated mouse macrophages to sucrose (0.009–0.03 M) leads to the formation of large phase- and electron-lucent, acid phosphatase-positive vacuoles in the perinuclear region. The vacuolization process and the uptake of sucrose-14C is blocked by inhibitors of pinocytosis and stimulated by calf serum in the medium. These results suggest the uptake of sucrose by pinocytosis and its subsequent segregation and storage in secondary lysosomes. The addition of sucrose also increases the total content of three macrophage lysosomal hydrolases. The addition of invertase to the environment of sucrose-laden macrophages leads to the prompt shrinkage of the sucrose-containing lysosomes. This is accompanied by the intracellular hydrolysis of sucrose to fructose and glucose residues which are promptly excreted into the medium. The uptake of invertase, as indicated by the shrinkage of sucrose-containing vacuoles, is blocked by inhibitors of pinocytosis. No effect was noted when invertase was added to macrophages laden with Ficoll, a polysucrose which is not hydrolyzed by the enzyme. The influence of other carbohydrates was then investigated. Monosaccharides with molecular weights up to 220 did not produce vacuolization. However, a certain number of di-, tri-, and tetrasaccharides produced vacuolization identical with that of sucrose. Each of the disaccharides which produced vacuolization was resistant to the complement of macrophage hexosidases, whereas those that were ineffective were degraded by either macrophage or serum enzymes. The addition of β-glucosidase to cellobiose-laden macrophages resulted in the shrinkage of vacuoles but did not alter the vacuoles of sucrose containing cells. The ability of small, neutral carbohydrates to produce lysosomal swelling is dependent upon both molecular weight and their resistance to lysosomal hydrolases.
TL;DR: Single units in the medial forebrain bundle and elsewhere in the preoptic area of anesthetized male rats responded to electrical shocks of the olfactory bulb and to odors and changes in firing rates in the mesencephalic reticular formation were closely associated with changes in the EEG.
TL;DR: Results show strong support for the hypothesis that a specifically adrenergic hypothalamic system is involved in the eating behavior of the rat, and the reverse sequence of these drugs did not elicit eating.
TL;DR: Preparations of bovine pancreatic deoxyribonuclease obtained by the ammonium sulfate precipitation procedure of Kunitz can be further purified by chromatography on sulfoethyl-Sephadex at pH 4.70 and show that the enzyme contains glucosamine and mannose and establish DNase as a glycoprotein.