Innervation of the synovial membrane of the cats joint capsule

Summary Results of investigations on the occurrence of nerve fibres and endings in the synovial membrane of the knee and elbow joint in the cat are reported. The stratum synoviale contains only autonomic fibres, running in the adventitia of arteries.Free nerve endings are lacking in the stratum synoviale. Simple Pacinian corpuscles with an inner core are occasionally observed in the border zone between the stratum synoviale and fibrosum. The ultrastructure of these endorgans resembles that of Pacinian corpuscles in the hairless and hairy skin of the cat.     

The involvement of the anticodon adjacent modified nucleoside N-(9-(BETA-D-ribofuranosyl) purine-6-ylcarbamoyl)-threonine in the biological function of E. coli tRNAile.

tRNAile was isolated from E. coli Cp 79 (leu-, arg-, thr-, his-, thiamin-, RCrel) which had been grown on a sub-optimal concentration of thr and was found to contain an average of 50% less N-[9-(beta-D-ribofuranosyl)- purin-6-ylcarbamoyl]threonine, t6Ado, than tRNAile from cells grown on an optimum concentration of thr and containing a normal complement of t6Ado. The two tRNA's were identical in their ability to be aminoacylated, to accept the 3'-terminal dinucleotide, and to form an ile-tRNAile-Tu-GTP complex. In contrast, the t6Ado-deficient-tRNA was significantly less efficient in binding to ribosomes compared to the normal tRNA. This difference was seen in the binding of deacylated tRNA and in the nonenzymatic and enzymatic binding of ile-tRNA, all in response to poly AUC. The t6Ado-deficient ile-tRNA demonstrated no binding at Mg2+ concentrations less than or equal to 10 mM, while the normal ile-tRNA bound at low Mg2+ concentrations. Tetracycline had the same effect on the normal as on the t6Ado-deficient ile-tRNA binding. As a control, the binding of phe-tRNA (which does not contain t6Ado) from normal and thr-starved cells in response to poly U was identical. It was concluded that t6Ado is required for proper codon-anticodon interaction.     

Conformation of RNA in situ as studied by acridine orange staining and automated cytofluorometry.

Human erythroblasts which are prereticulocyte maturation stages of red blood cells were studied by light microscopic cytochemistry and electron microscopy to provide more information on the ultrastructure of the micronucleoli which are terminal stages of nucleolar changes found during maturation of these cells. As indicated by light microscopy of smeared cells, micronucleoli were virtually the only types of nucleoli present in the last stages of maturing erythroblasts, i.e., polychromatic and orthochromatic (late polychromatic) erythroblasts. Accordingly, they were not portions of the periphery of other nucleoli. Inasmuch as most of the micronucleoli exhibited characteristic segregation of nucleolar fibrillar and granular components they presumably are producing little if any preribosomal RNA, since such segregation generally reflects inhibition of nucleolar RNA synthesis.     

Acetylcholine receptors in normal and denervated rat diaphragm muscle. I. Purification and interaction with [125I]-alpha-bungarotoxin.

Acetylcholine receptors have been purified from junctional regions of normal rat diaphragm muscle and from extrajunctional regions of denervated diaphragm. The reaction of purified receptors with [122I]-alpha-bungarotoxin has been investigated by kinetic methods. The toxin-receptor complexes dissociated in a biphasic manner at 35 degrees with a rapidly dissociating component (t1/2 = 4 hr) and a slowly dissociating component (t1/2 is greater than or equal to 100 hr). The association reaction between toxin and receptor did not obey simple second-order kinetics but could be analyzed in terms of two classes of binding sites corresponding to the two rates of dissociation. This treatment of the data allowed derivation of association rate constants for the two sites. Value obtained for the dissociation constants were 3.7 times 10(-10) and less than or equal to 0.4 times 10(-10) M for the junctional receptor and 1.7 times 10(-10) and is less than or equal to 0.2 times 10(-10) M for the extrajunctional receptor. In each case it is the more tightly binding component that associates and dissociates more slowly. Receptors present in crude preparations were comparable to purified receptors in their reaction with [125I-alpha-bungarotoxin. The validity of the two site model is discussed in relation to the kinetic studies.     

Acetylcholine receptors in normal and denervated rat diaphragm muscle. II. Comparison of junctional and extrajunctional receptors.

Acetylcholine (ACh) receptors have been purified separately from normal rat diaphragm muscle (junctional receptors) and from extrajunctional regions of denervated diaphragm (extrajunctional receptors) in order to compare their properties. The toxin-receptor complexes of the two receptors were indistinguishable by gel filtration and by zone sedimentation in sucrose gradients, and showed identical precipitation curves with rabbit antiserum to the eel ACh receptor. Both toxin-receptor complexes bind concanavalin A and are therefore probably glycoproteins. Low concentrations of d-tubocuratine (dTC) were more effective in decreasing the rate of toxin binding to junctional than to extrajunctional receptors. The apparent dissociation constant for dTC binding to the junctional receptor was 4.5 X 10 minus 8 M, whereas the value for the extrajunctional receptor was 5.5 X 10 minus 7 M. When the complexes were analyzed by isoelectric focusing, the junctional complex focused at approximately 0.15 pH unit lower than the extrajunctional complex. This result was also found with crude preparations of receptor. We conclude that junctional and extrajunctional receptors are similar but distinct molecules. The properties of receptors present in neonatal diaphragm muscle were also examined and found to be similar to those of receptors in denervated muscle, as shown by dTC inhibition and isoelectric focusing.     

Development of the nephrons of the mesonephros of chicken embryo]

The number of nephron populations in the postinduction period was established in 6- and 8-days chicken embryos and the development of an individual nephron and its parts was studied. The investigation by microdissection method has shownand the number of nephrons is different along the length of the kidney. Only two layers ofthe nephrons were found in the cranial portion, while in the caudal direction their number increased up to 4-6 populations which distinguished from one another by the glomerule position, the length of the nephron and its segments. All the populations of the ventral nephrons enter immediately into the mesonephritic (Wolffian) duct, while the dorsal nephrons have a system ofcollecting tubes by which they are connected with the mesonephric duct. The development of mesonephros was accompained by the increase of the absolute length of the nephrons of all populationsand their segments.Laboratory of Individual Development, Institute of Physiology, Czechoslovakian Academy of Sciences, Prague, and Laboratory of the Evolution of the Kidney and Water-Salt Exchange, Sechenov Institue of Evolutionary Physiologyand Biochemistry, Leningrad.     

Proteolytic activity associated with human erythrocyte membranes. Self-digestion of isolated human erythrocyte membranes.

At least two kinds of enzymes are active in the proteolytic self-digestion of erythrocyte membranes. The specific activities of these enzymes do not decrease with repeated washings of purified stroma. The effects of a variety of inhibitors on the membrane preparation's capacity to digest 125-I-labelled casein, covalently linked to latex beads, have been examined. Pepstatin-inhibitable enzyme, active at low pH, digests the membrane extensively to small polypeptide fragments. Spectrin, located at the internal part of the membrane, is readily degraded. Diisopropylfluorophosphate-inhibitable enzyme, active at pH 8-9, has only limited digestive capacity. Some of the membrane components, such as the small molecular weight glycoproteins, are resistant to digestion. The restricted capacity of digestion is due to the membrane molecular arrangement; increased disaggregation removes the restriction and increases the activity. Spectrin is not digested unless the membrane topography is disrupted by NP-40 neutral detergent. These observations suggest that the enzymes active at basic pH are located external to the cell. Intact cells do possess a limited capacity to degrade 125-I-labelled casein when their surfaces are brought into contact with substrate-coated beads.     

Purification and properties of rabbit liver phosphorylase phosphatase.

A procedure for the purification of rabbit liver phosphorylase phosphatase is described. The specific activity of the preparation is 2,100 units/mg of protein, representing a 25,000-fold purification. During the initial steps of the purification a large activation of enzyme activity was observed. The molecular weight of the purified enzyme was estimated by Sephadex G-75 chromatography to be 35,000, and by sucrose density ultracentrifugation to be 34,000 (2.9 S). On Na dodecyl-SO4 polyacrylamide disc gel electrophoresis a single component with a molecular weight of 34,000 was observed. The pH optimum is 6.9 to 7.4, and the Km for rabbit muscle phosphorylase alpha is 2 muM. The same procedure is also applicable to the extensive purification of phosphorylase phosphatase from rabbit muscle.