S-100 protein synthesis by isolated polyribosomes from rat brain

The radioactive proteins synthesized in a cell-free system and released from polyribosomes from rat brain were analyzed for the presence of a protein found only in the nervous system. Polyribosomes from rat liver were also studied to demonstrate the organ specificity of the radioactive product synthesized in vitro. The S-100 protein constituted 0.15 percent of the radioactive proteins released from brain polyribosomes.     

Uptake of isolated chloroplasts by mammalian cells

Mouse fibroblasts (L cells) in suspension culture incorporated isolated chloroplasts of spinach and African violets and isolated mitochondria of chicken liver. The organelles resided in the cell cytoplasm and were not contained in vacuoles or digestion vesicles. Green cells divided like normal cells. Green chloroplasts were followed for five cell generations or 5 days, at which time hybrid cells were greatly outnumbered by nongreen progeny cells. The ingested chloroplasts retained their structural integrity as determined by electron microscopy of organelles and hybrid cells and by analysis of photochemical activity and DNA in chloroplasts reisolated from cells after 1 or 2 days in culture.     

Fossil evidence on origin of the mammalian brain

Many hypotheses have been postulated regarding the early evolution of the mammalian brain. Here, x-ray tomography of the Early Jurassic mammaliaforms Morganucodon and Hadrocodium sheds light on this history. We found that relative brain size expanded to mammalian levels, with enlarged olfactory bulbs, neocortex, olfactory (pyriform) cortex, and cerebellum, in two evolutionary pulses. The initial pulse was probably driven by increased resolution in olfaction and improvements in tactile sensitivity (from body hair) and neuromuscular coordination. A second pulse of olfactory enhancement then enlarged the brain to mammalian levels. The origin of crown Mammalia saw a third pulse of olfactory enhancement, with ossified ethmoid turbinals supporting an expansive olfactory epithelium in the nasal cavity, allowing full expression of a huge odorant receptor genome.     

Adenosine 3',5'-monophosphate-dependent protein kinase from brain

Adenosine 3',5'-monophosphate at a concentration of 5 x 10(-7) mole per liter causes a 400 percent increase in the rate of phosphorylation of histone catalyzed by a partially purified enzyme preparation from rabbit brain. The data provide the first direct evidence of a biochemical action of adenosine 3',5'-monophosphate in the brain.     

Cytosolic calcium during contraction of isolated mammalian gastric muscle cells

During activation of visceral smooth muscle there is an increase in cytosolic-free calcium, but the source (intracellular calcium release or calcium influx), kinetics, and stoichiometry of this increase have not been determined. Here, the fluorescent indicator, quin2-acetoxymethyl ester, was used to measure directly cytosolic-free calcium during contraction of isolated stomach muscle cells induced by the two neuropeptides cholecystokinin-octapeptide and Met-enkephalin as well as acetylcholine. An increase in cytosolic-free calcium was seen that was (i) dependent on the concentration of contractile agonist, (ii) derived from intracellular sources (that is, not significantly affected by removal of ambient calcium or addition of a calcium channel blocker), and (iii) kinetically and stoichiometrically related to net calcium efflux and contraction. In contrast, the increase in cytosolic-free calcium induced by depolarizing concentrations of potassium was caused by influx of calcium through voltage-dependent calcium channels.     

Partial characterization of 21.5K myelin basic protein from sheep brain

The 21,500 molecular weight (21.5K) variant of myelin basic protein (MBP) was isolated from sheep brain and partially characterized. Digestion with cyanogen bromide and trypsin yielded peptides which showed that approximately 30 additional amino acids were inserted at the equivalent of the amino acid at position 57 in the bovine 18.5K MBP sequence. An unusually hydrophobic peptide Pro, Val, Leu, Trp, Lys was present in this region. Ornithine was present in hydrolyzates of 21.5K MBP, but it was not detected in any of the peptides.     

The primary structure and heterogeneity of tau protein from mouse brain

Tau protein is a family of microtubule binding proteins, heterogeneous in molecular weight, that are induced during neurite outgrowth and are found prominently in neurofibrillary tangles in Alzheimer's disease. The predicted amino acid sequences of two forms of tau protein from mouse brain were determined from complementary DNA clones. These forms are identical in their amino-terminal sequences but differ in their carboxyl-terminal domains. Both proteins contain repeated sequences that may be tubulin binding sites. The sequence suggests that tau is an elongated molecule with no extensive alpha-helical or beta-sheet domains. These complementary DNAs should enable the study of various functional domains of tau and the study of tau expression in normal and pathological states.     

Glutamate uptake by the isolated toad brain

The isolated toad brain accumulates L-glutamate against strong concentration gradients until a tissue-to-medium concentration ratio of about 3000 : 1 is attained. The accumulated glutamate does not equilibrate with most of the endogenous tissue glutamate but is converted rapidly to glutamine and released into the medium. This mechanism may be involved in the preservation of low extracellular levels of cerebral glutamate.     

Histone and DNA in isolated nuclei from chicken brain,liver, and erythrocytes

In isolated brain and liver nuclei the ratio of histone to deoxyribonucleic acid is lower than in nuclei from erthrocytes. Deoxyribonucleoproteins from brain and liver, in contrast to deoxyribonucleoproteins from erythrocytes, are more soluble in isotonic sodium chloride.     

A gustotopic map of taste qualities in the mammalian brain

The taste system is one of our fundamental senses, responsible for detecting and responding to sweet, bitter, umami, salty, and sour stimuli. In the tongue, the five basic tastes are mediated by separate classes of taste receptor cells each finely tuned to a single taste quality. We explored the logic of taste coding in the brain by examining how sweet, bitter, umami, and salty qualities are represented in the primary taste cortex of mice. We used in vivo two-photon calcium imaging to demonstrate topographic segregation in the functional architecture of the gustatory cortex. Each taste quality is represented in its own separate cortical field, revealing the existence of a gustotopic map in the brain. These results expose the basic logic for the central representation of taste.     

Epinephrine metabolism in mammalian brain after intravenous and intraventricular administration

Epinephrine given intravenously or intraventricularly has a half-life in the brain of the rat of 2 to 2.5 hours. After intravenous administration of the drug the principal route of metabolism is O-methylation, whereas after intraventricular administration the principal route is conjugation.     

Pinealocyte projections into the mammalian brain revealed with S-antigen antiserum

Neural processes from mammalian pinealocytes have been discovered in several brain areas. These processes were visualized immunocytochemically in the Djungarian hamster, Phodopus sungorus, with an antiserum against bovine retinal S-antigen and traced as far as the region of the posterior commissure and habenular nuclei. This result indicates that pineal-to-brain connections exist in the mammal, and that the mammalian pineal gland, currently thought of only as a neuroendocrine organ, may communicate directly with select brain regions by way of these projections. The existence of mammalian pinealocyte projections is consistent with the view that these cells are not of glial origin but are derivatives of photoreceptor cells of the pineal complex of lower vertebrates that transmit signals to the brain by neural projections.     

State of dynamic equilibrium in protein of mammalian cells

Labeled strain L cells in suspension tissue culture showed no degradation of protein when maintained in logarithmic growth. Although the protein of these cells was not in dynamic equilibrium, the conclusions cannot be transferred to the intact mammalian organism.     

Synthesis of RNA-polyadenylic acid by isolated brain nuclei

Nuclei, isolated from mouse brain tissue at various stages of postnatal development and incubated under cell-free conditions, synthesized RNA molecules that were associated with polyadenylic acid [poly(A)]. The RNA synthesized by these nuclei was similar to the poly(A)-associated products described for intact eukaryotic cells. The brain nuclei synthesized a similar proportion of RNA-poly(A) in the presence either of Mg(2+) or of Mn(2+) with (NH(4))(2)So(4). The RNA from neonatal brain nuclei appeared to have a greater proportion of poly(A)-containing RNA than nuclear products obtained from more mature neural tissue.     

A G protein directly regulates mammalian cardiac calcium channels

A possible direct effect of guanine nucleotide binding (G) proteins on calcium channels was examined in membrane patches excised from guinea pig cardiac myocytes and bovine cardiac sarcolemmal vesicles incorporated into planar lipid bilayers. The guanosine triphosphate analog, GTP gamma S, prolonged the survival of excised calcium channels independently of the presence of adenosine 3',5'-monophosphate (cAMP), adenosine triphosphate, cAMP-activated protein kinase, and the protein kinase C activator tetradecanoyl phorbol acetate. A specific G protein, activated Gs, or its alpha subunit, purified from the plasma membranes of human erythrocytes, prolonged the survival of excised channels and stimulated the activity of incorporated channels. Thus, in addition to regulating calcium channels indirectly through activation of cytoplasmic kinases, G proteins can regulate calcium channels directly. Since they also directly regulate a subset of potassium channels, G proteins are now known to directly gate two classes of membrane ion channels.     

Estrogen formation by the isolated perfused rhesus monkey brain

Perfusion of two isolated brains from immature male rhesus monkeys with [(3)H]androstenedione resulted in the identification of free and conjugated [(3)H]estrone and free [(3)H]estradiol from the perfusates. In the dissected cerebral tissues, estrogens were recovered only from the hypothalamus and limbic system. The production of estrogens from androstenedione during the 40-minute perfusions in these two experiments totaled 1.58 and 2.83 nanograms.     

Neuronal perikarya of rat brain isolated by zonal centrifugation

Cerebral cortex and hippocampus of rat were disrupted in a specially designed tissue-press and prepared as a 2 percent suspension in 10 percent buffered Ficoll medium and fractionated by density-gradient centrifugation in the B XIV zonal rotor. The suspension was injected into a buffered 30 percent Ficoll, 58 percent sucrose discontinuous gradient previously loaded in the B XlV zonal rotor spinning at 3500 revolutions per minute. Intact neuronal perikarya were recovered as a discrete band in the dense sucrose zone of the gradient after centrifugation at 35,000 revolutions per minute for 45 minutes.