Binding of protein kinase substrates by fluorescently labeled calmodulin

A synthetic protein kinase substrate, PRO-LEU-SER-ARG-THR-LEU-SER-VAL-SER-SER-NH₂, undergoes calcium-dependent binding by calmodulin. Phosphorylation of the peptide decreases its affinity for calmodulin with the dissociation constant increasing from 2.4 to $\text{ca}$. 7 mM. The results are consistent with the suggestion that calmodulin and the cAMP-dependent protein kinase can act on common recognition sequences.     

Analysis of radioactive and nonradioactive purine bases,nucleosides, and nucleotides by high-speed chromatography on a single column

The concentrations of radioactive and nonradioactive purine bases, purine nucleosides, purine mono-, di-, and trinucleotides in acid extracts of fibroblasts were determined by anion-exchange column chromatography. The concentrations of nonradioactive components were determined by computerized integration of the signal from a double-beam uv-detector. The radioactive metabolites were quantitated by high-efficiency, continuous liquid scintillation counting, employing a discrete sample transport system.     

Structural changes in light- and dark-adapted compound eyes of the australian earwig Labidura riparia truncata (dermaptera)

The apposition acone eye of Labidura is relatively small—550–600 facets—with a thick corneal lens and shallow retina. The retinula cell columns are each formed of six peripheral cells plus two central cells, a partially fused rhabdom, and dense pigment in two or three cell types. Upon adaptation from light to dark, the most striking photomechanical response is a proximal broadening of the cone cells, which results in a 38-fold increase in cross-sectional area of the aperture. While longitudinal rhabdom movement is small, microvillar diameters swell in response to light and contract in the dark. Irregularities of facet pattern and shape, and in ommatidial alignment were found, particularly towards eye margins. Three types of interommatidial sense organs on the eye surface are described, one of which has not been previously reported. An argument is presented to explain how the field of view and sensitivity are both apparently decreased in the acone eye by exposure to light.     

Structural changes during the transformation of bacteriophage T4 polyheads: II. Evidence that a conformational change in the major capsid protein precedes the expansion

The shell of the bacteriophage T4 prehead is transformed after the maturation cleavages from a fragile to a highly chemically resistant structure. A “cleaved but anchored” shell, in which the capsid protein has been cleaved but expansion to the mature structure has not yet occurred, is thought to be an intermediate in the transformation. We have compared native, trypsinized, temperature-sensitive mutant, and cleaved but anchored polyheads for differences and similarities in their capsomeres. Our results show that the altered capsomeres of the cleaved but anchored state must be attributed to a conformational change in the subunits, and not simply to the loss of the amino-terminal peptide by proteolysis.     

Dorsal giant fibre septum of earthworm. Fine structural details and further evidence for gap junctions

The fine structure of the dorsal giant fibre septa of earthworm (Lumbricus terrestris and Eisenia foetida) was studied by thin sectioning. E-PTA, BIUL and ZIO impregnation were carried out to characterize the various membrane specializations found. A septum, which is formed by two axon membranes only ca. 7 nm apart, is a heterogeneous structure showing a number of different specializations (intermediate junctions, dense projection-like humps, septate regions, vesicles quite often associated with a widened intercellular gap and membrane thickening). Septal areas referred to as septal complexes are of particular interest. They comprise up to 20% of septal cross-sections and are characterized by membrane appositions (diameter ca. 25 nm) which bridge the septal gap, protrude 16-25 nm into the respective axoplasms, and form a more or less hexagonal array with a centre-to-centre spacing of ca. 33 nm (ca. 29 nm after E-EPTA treatment) in en face sections. We interpret the septal complexes as gap junctions, i.e. sites of electronic coupling, and emphasize their unusually large dimension. The vesicles found at the septum could not be stained by ZIO treatment.     

(2R*, 3S*)-1-[18F]fluoro-2,3-bis(4-hydroxyphenyl)pentane [( 18F]fluoronor-hexestrol), a positron-emitting estrogen that shows highly-selective, receptor-mediated uptake by target tissues in vivo

The positron-emitting, non-steroidal estrogen (2R*, 3S*)-1-[18F]fluoro-2,3-bis(4-hydroxyphenyl)pentane [( 18F]-fluoronor-hexestrol), has been prepared by fluoride ion displacement on a labile trifluoromethanesulfonate (triflate) derivative of a suitably protected precursor, followed by removal of the aryl triflate groups with lithium aluminum hydride and purification by HPLC. In immature female rats, this compound is taken up selectively by the uterus and is retained for prolonged periods, due to its binding to the estrogen receptor. This compound and related 18F-labeled estrogens thus appear to be promising agents for imaging estrogen receptor-positive breast tumors in humans.     

Increasing the sensitivity of the anthrone method for carbohydrate.

The colour yield from glucose and the anthrone reagent is more than doubled in the presence of hydrochloric and formic acids. By using a suitable heating time, approximately equal colour yields can be obtained from glucose and fructose.     

Morphine reduces cerebellar guanosine-3',5'-cyclic monophosphate content and elevates cerebrospinal fluid guanosine-3',5'-cyclic monophosphate content in rhesus monkey.

Morphine administration (20 mg/kg) to awake rhesus monkeys which had been chronically implanted with catheters for aspiration of cerebrospinal fluid (CSF) produced a significant elevation in the CSF level of guanosine-3′, 5′-cyclic monophosphate (cGMP). Additionally, biopsies of cerebral and cerebellar cortex were taken from anesthetized monkeys given 20 mg/kg of morphine sulfate. Only cerebellar cGMP levels changed significantly, showing a 35% decrease relative to anesthetized controls. Although the controlling factors of brain tissue and CSF cGMP levels are poorly understood, the possibility of a reciprocal relationship between cGMP levels in certain brain regions and in CSF under some conditions is discussed.     

Rapid group separations of nucleotides and related compounds on silica columns

Nucleosides, bases, and nucleotides can be separated from one another rapidly (10–15 min) on 1-ml silica cartridges. Samples adjusted to 4 mm ammonium borate, 90% acetonitrile are loaded onto 1-ml columns equilibrated with the same solvent. Bases do not absorb to the silica under these conditions. Nucleosides are eluted with 16 ml of 0.5 m acetic acid in 90% acetonitrile. Nucleotides are then eluted with water. The 1-ml silica columns have performed well with samples up to 10 ml in volume. We have found the procedure to be quantitative and the gels to have high capacity (61 μmol Cyd/ml silica). Acid extracts from a large number of cells (10⁸) have been processed on a single cartridge.     

Improved sensitivity of iodinated histamine-prostaglandin radioimmunoassay by prostaglandin methyl esters

Use of (¹²⁵I)-labeled histamine-prostaglandin tracer increases the sensitivity of the radioimmunoassays of prostaglandin derivatives. Six different antisera were produced for prostaglandins and their derivatives (prostaglandins E₁, E₂, F_1α, F_2α, 13,14-dihydro-15-ketoprostaglandin E₂, and 13,14-dihydro-15-ketoprostaglandin F_2α) and were investigated with the corresponding tritiated and lodinated tracers. Displacement of iodinated tracers by the methyl esters of the prostaglandin compounds resulted, in most cases, in a three- to fivefold increase in sensitivity compared to unesterified inhibitors. Esterification also caused some alteration in the specificities observed. Our results suggest that conformational changes in the esterified prostaglandins (tracer and inhibitor) could explain these charges.     

Effects of chronic administration of delta-9-tetrahydrocannabinol and cannabidiol on rat testicular esterase isozymes

The effects of Δ⁹-tetrahydrocannabinol and cannabidiol on the esterase isozymes of rat testicular tissue were examined using acrylamide gel electrophoretic techniques followed by staining for non-specific esterase activity. Both Δ⁹-tetrahydrocannabinol and cannabidiol caused a specific depression of an esterase isozyme located in the interstitial tissue of the testis.     

Horseradish peroxidase. XXV. An electron spin resonance study of the low temperature photochemical reaction of compound I.

The insoluble acrosome granule content of sea urchin sperm consists of a single 30,500 dalton protein named bindin. Bindin mediates species-specific recognition and adhesion of sperm to the egg surface. Bindin from $\text{Strongylocentrotus purpuratus}$ (Sp) and $\text{Strongylocentrotus franciscanus}$ (Sf) have tyrosine as their single N-terminal amino acid. The pI of Sp bindin is 6.62 and of Sf 6.59. Amino acid analysis reveals almost identical composition between the two species for 16 amino acids. Only two (or three) amino acids, Pro and Asx, show large species differences. Tryptic peptide maps of the two species of bindin show very similar patterns with 24 spots of identical correspondence.     

Nonuniform distribution of fibronectin during avian limb development

Using indirect immunofluorescence we have examined the distribution of the cell surface and extracellular matrix glycoprotein fibronectin at the epithelial-mesenchymal interface and in the mesenchyme of developing chick and duck wing buds. At all stages examined, in both species, staining for fibronectin is greatly enhanced in the basement membrane subjacent to the apical ectodermal ridge (AER), a site of inductive tissue interaction, relative to the epithelial basement membranes in the noninductive dorsal and ventral limb epithelial-mesenchymal interfaces. In stage 23, 25, and 28 chick limb buds, staining for fibronectin is uniform in the least mature distal mesenchyme, retained between more proximal cells undergoing precartilage condensation and lost in those regions undergoing myogenesis, and persistent in all but the most mature cartilage present at the latest stage examined. These results are consistent with a role for fibronectin in AER-induced limb outgrowth, and with a transient role for the glycoprotein in the formation of the skeletal pattern of the limb.     

Tumor cell killing by macrophages activated in vitro with lymphocyte mediators. II. Inhibition by inhibitors of protein synthesis.

The effect of inhibitors of protein synthesis on the killing of tumor cells by in vitro activated macrophages was determined. Cytotoxicity was inhibited by concentrations of puromycin, pactamycin, and actinomycin D that almost completely inhibited protein synthesis by guinea pig macrophages, but not by concentrations of drug that inhibited protein synthesis by only ± 50%. Cytotoxicity was inhibited when the effector macrophages were pretreated with the metabolic inhibitors, but not when the drugs were added 30 to 60 min after the initiation of the reaction. Pretreatment with puromycin or pactamycin also markedly inhibited the binding of tumor cells by mediator activated macrophages. These results are consistent with the hypothesis that one possible mechanism by which inhibitors of protein synthesis inhibit macrophage mediated cytotoxicity is by inhibiting close contact between effector and target cells. The finding that pretreatment of activated macrophages with trypsin also inhibits tumor cell killing suggests that protein synthesis may be necessary to maintain an adequate number of “recognition structures” on the macrophage membrane, structures that mediate the initial contact between the activated macrophage and the target tumor.     

Synthetic studies on amino-alpha-glycosides of aminocyclitols. Synthesis of kanamycin analogues

A diastereoisomer of Kanamycin C has been synthesized by a modified Koenigs—Knorr reaction of 3,4,6-tri-O-acetyl-2-(2,4-dinitroanilino)-2-deoxy-α-D-glucopyranosyl bromide with 4-O-(3-acetamido-2,4,6-tri-O-benzyl-3-deoxy-α-D-glucopyranosyl)-N,N′-di[(benzyloxy)carbonyl]-2-deoxystreptamine. Several Kanamycin analogues were synthesized by a similar condensation reaction. Each of the condensed products was isolated as its crystalline tetra-N-acetyl derivative and was proved by n.m.r. spectroscopy in D₂O to have the α-configuration.