The localization of acetylcholinesterase activity in the spinal ganglia of the adult fowl studied by electron microscope histochemistry

Summary AChE activity was localized in spinal ganglia of adult fowls at the electron microscope level using Karnovsky’s method. Controls with BW 284 C 51 were carried out. In the neuronal bodies, AChE activity was evident within the rough-surfaced cisternae of the endoplasmic reticulum, including the perinuclear cisterna and the subsurface cisternae, and sometimes in the innermost cisternae of the Golgi complex. AChE activity was also demonstrated along the axolemma and associated with smooth-surfaced vesicles and tubules in the initial segment of the axon, in all the ganglionic myelinated fibers examined by serial section analysis and in more than half of the ganglionic unmyelinated fibers examined by this method. In the myelinated fibers the reaction product appeared more abundant at the level of the nodes of Ranvier than in the internodal segments. Both in the myelinated and unmyelinated fibers a considerable quantitative variability of reaction product was observed among the various sections of the same fiber. These results were compared with those previously obtained in the spinal ganglia of the chick embryo using the same histochemical method. This research was supported by a grant of the National Research Council (C.N.R.), Italy, and of the Deutsche Forschungsgemeinschaft (DFG), Federal Republic of Germany. 1 AChE=acetylcholinesterase (=true or specific cholinesterase); ACh=acetylcholine; ChAc=choline acetylase (=choline acetyltransferase).     

Uptake of peroxidase by calcitonin inhibited osteoclasts

Summary The present electron microscopic histochemical study demonstrates that osteoclasts from calcitonin treated bone are able to take up organic macromolecules even though the ruffled border has disappeared. The absorption occurs around the entire periphery of the osteoclast, but the amount of absorbed peroxidase seems to be reduced in comparison with that of untreated cells. It is concluded that the effect of calcitonin on osteoclasts is primarily a cessation of the exocytosis and the concomitant disappearance of the ruffled border.This research was supported by the Danish Medical Research Council, grant No. 512-7184     

Sequence organization in Xenopus DNA studied by the electron microscope.

Xenopus laevis DNA was extracted from red blood cells and sheared to a mean length of 2780 nucleotides. The DNA was stripped of foldback-containing fragments and incubated to C₀t 10 (mol · s · l⁻¹), allowing most repetitive sequences to form duplex structures. Duplex-containing fragments were eluted from an hydroxylapatite column and visualized for electron microscopy by spreading from 57% formamide according to the modified Kleinschmidt technique of Davis et al. (1971). The mean length of the fragments observed was 2445 nucleotides. A total of 1700 DNA strands were photographed and studied. Less than 5% of the total strand length was in uninterpretable structures. Every molecule falling within the confines of the plates was included in the sample. Over 50% of the total strand length in the sample was found in structures bearing at least one interspersed repetitive sequence duplex terminated by four single-strand regions. The fraction of DNA present in duplex regions was almost exactly that predicted if the duplex regions represent all the interspersed middle repetitive sequence in the Xenopus genome. Direct measurement of visualized duplexes shows that the mean length of interspersed repetitive sequence elements in this genome is 345 nucleotides. Duplex length was shown to be independent of the length of the strands bearing the duplexes. These observations provide direct confirmation of the length of approximately 300 nucleotides indicated for interspersed repetitive sequences by earlier physical-chemical studies 011 Xenopus DNA. In strands carrying two duplexes terminated by single-strand regions the interduplex, or single-copy sequence element length could be measured. Sequence interspersion curves generated from these data are roughly consistent with those derived earlier from measurements of hydroxylapatite binding as a function of fragment length.     

The central region of the synaptonemal complex inBlaps cribrosa studied by electron microscope tomography

The synaptonemal complex (SC) in the beetleBlaps cribrosa contains a highly organized central element (CE), two flanking lateral elements (LEs), and a number of regularly spaced transverse filaments (TFs) crossing the central region. The CE is built like a ladder with two longitudinal components running in parallel and a number of regularly spaced transverse CE components, briding the two longitudinal components. The CE is multi-layered with the ladders of the individual layers more or less in register. Essentially every TF originates in one of the LEs, crosses the CE through a transverse CE component and reaches the opposite LE; every transverse CE component in a given layer corresponds to one, and only one, TF. In a CE layer, short irregular pillars form the junctions between the transverse and longitudinal CE components. Adjacent pillars are connected to each other by fine fibrous bridges: the two pillars in the same transverse CE component are linked, and so are the pillars along each longitudinal component, and also more occasionally adjacent pillars in separate CE layers. It is proposed that a TF with the two associated short pillars represents the structural unit in the central region. The ordered structure of the CE is accomplished by linking adjacent pillars to each other into the well-defined three-dimensional organization of the CE.     

Fusion of two F-prime factors inEscherichia coli studied by electron microscope heteroduplex analysis

Summary A fused F prime factor was obtained from a mating of arecA donor carrying an F' factor containing the genesmetBJF, ppc andargECBH (KLF5) with arecA recipient carrying an F' factor containingatt80, trp andlac (F155). Lysogenization of this fused F-prime factor with cI⁸⁵⁷ h80 phage followed by thermoinduction produced the transducing phages 80dmetBJF and 80dppcargECBH. This kind of fusion provides a general procedure for the construction of transducing phages carrying genes from different regions of theE. coli genome. To understand the mechanism of this fusion, the parental F prime factors (F155 and KLF5) were analyzed by the electron microscope heteroduplex technique.F155 has a length of 176±3 kilobases including two substitutions. The F sequence 0 F-2.8 F has been substituted by 53 kb of chromosomal DNA including thelac operon and the F sequences 8.5 F-16.3 F has been substituted by 27 kb of a chromosomal sequence includingatt80 and thetrp operon.KLF5 contains 221±4 kilobases of DNA (molecular weight, 148 megadaltons). It contains complete F and the segment of theE. coli chromosome frompolA torif. The F sequence 2.8 F-8.5 F known to be involved in F specific recombination inrecA ⁺ andRecA backgrounds occurs twice on KLF5, once at each of the junctions of F DNA with chromosomal DNA. The population of closed circular plasmid molecules extracted from KLF5-containing strains is heterogeneous. It is proposed that this heterogeneity is due to intramolecular recombination events occurring in KLF5 between the duplicated 2.8 F-8.5 F sequences. Such recombination can account for the genetic instability of KLF5 observed in bothrecA ⁺ andrecA hosts. The F sequence 2.8 F-8.5 F (also called ) is one of the characterized integration sequences on F.A model for the fusion of the parental F prime factors is proposed in which recombination between sequences bringsatt80 close to themetBJF genes. This is followed by a deletion of an F'lac factor. The resulting fused F' factor still carries two sequences and is therefore expected to be unstable. The closed circular molecules isolated from the fused F' containing strains show two different sizes of molecules. Genetic and physical analyses of these molecules are in agreement with the predicted instability of the fused F' factor and the existance of the sequence in the 80dmet phages isolated from fused F' and previously analyzed by the electron microscope heteroduplex technique.     

Some features ofNitella chloroplasts as revealed by the electron microscope

Summary Nitella chloroplasts when extruded from the large internodal cells and examined with the electron microscope often show daughter plastids in various stages of division as well as occasional external plastid protuberances. In the individual plastids the main mass of the chloroplast material appears to be concentrated in the outer portion of the plastid leaving a somewhat spongy interior. The extruded contents of ruptured plastids often contain particles of around 500 Å in diameter.Deceased, March 14, 1953     

Identification of osteoclasts and their differentiation from mononuclear phagocytes by enzyme histochemistry

A double staining method is presented which allows the enzyme histochemical differentiation between osteoclasts (mono- and multinucleated forms) and mononuclear phagocytes (macrophages, multinucleated inflammatory giant cells). Osteoclasts are characterized by a strong acid phosphatase activity whereas macrophages and inflammatory giant cells show a variable non-specific esterase activity. The described method may be useful in studying the osteoclast origin and the extraosseous distribution of these cells.     

Identification of osteoclasts and their differentiation from mononuclear phagocytes by enzyme histochemistry

Summary A double staining method is presented which allows the enzyme histochemical differentiation between osteoclasts (mono- and multinucleated forms) and mononuclear phagocytes (macrophages, multinucleated inflammatory giant cells). Osteoclasts are characterized by a strong acid phosphatase activity whereas macrophages and inflammatory giant cells show a variable non-specific esterase activity. The described method may be useful in studying the osteoclast origin and the extraosseus distribution of these cells.Supported by Deutsche Forschungsgemeinschaft, SFB 244,A1