The histones of some human tissues

1. Histones were examined from five human tissues, namely thymus, liver, placenta, bronchial tumour and peripheral leucocytes. 2. The four main histone fractions [F1, F2(b), F2(a), and F3] were isolated and characterized. 3. The amino acid analyses, N-terminal group analyses and electrophoretic patterns were very similar to those of the corresponding fractions of calf thymus. 4. The yields of fractions F1 and F2(b) were high in human thymus, in human bronchial tumour and in some preparations of normal human leucocytes. 5. It is concluded that the pattern of nuclear histones found in lower forms of life was conserved during the evolutionary process leading to man.     

The determination of the specific activity of picomolar amounts of long-chain acylcarnitine esters

Measurement of the specific activity of cellular pools of long-chain acylcarnitines is complicated by interference of other labeled cellular lipids, especially phosphatidylcholine and sphingomyelin. To overcome these problems the lipid extract from rabbit aorta labeled with [1-¹⁴C]palmitate was treated with phospholipase C. Upon two-dimensional thin-layer chromatography, the long-chain acylcarnitines could be isolated in an area free of interfering radioactivity. Mobility of long-chain carnitines was inversely proportional to the fatty acid chain length. The amount of long-chain acylcarnitine was quantified from their carnitine content after alkaline hydrolysis using carnitine acetyltransferase.     

The measurement of nanogram amounts of piperidine in tissues by gas chromatography.

A gas chromatographic method is presented which allows the determination of piperidine in tissue in nanogram quantities. Reaction of the perchloric acid tissue extracts with 3,5-dinitro-4-chloro-benzotrifluoride followed by extraction with hexane, results in a derivative of piperidine suitable for electron capture detection. The specificity of the procedure is confirmed by combined gas chromatography - mass spectrometry. Using this procedure the mean concentration of piperidine in whole mouse brain was found to be 219 pmoles per gram of tissue. No significant difference between the concentration of piperidine in the brains of active and behavioral sleeping mice could be found.     

The measurement of nanogram amounts of acetylcholine in tissues by pyrolysis gas chromatography

Abstract— A method previously described for measuring ACh in biological effluents has been simplified and extended for use with tissues. The tissue is homogenized in acetonitrile containing propionylcholine as the internal standard and after centrifugation the acetonitrile is removed by shaking with toluene. To the aqueous solution is added a solution of KI-I₂ to precipitate the quaternary compounds. The precipitate is dissolved in aqueous acetonitrile and then drawn through a small column of ion-exchange resin to convert the periodides of the quaternary compounds to chlorides which are then simultaneously pyrolysed and gas chromatographed. On the column the pyrolytic product of choline has a slower retention time than that of acetylcholine; under these circumstances the choline present in tissues does not obscure the measurement of acetylcholine. Specificity was demonstrated by several procedures including mass spectroscopy. The method can measure 25 ng (171 pmoles) of acetylcholine in extracts of brain, simply, and with high reproducibility. With the usual gas chromatograph, 16 samples can be run in a working day. The content of acetylcholine in rat brain was 26.4 nmol/g or almost precisely the values found with other gas chromatographic methods. The pyrolytic method was shown to be applicable to the detection of biologically interesting substances other than choline esters, including betaine, carnitine and the non- quaternary compound, ?-aminobutyric acid, which is readily converted to a volatile compound (probably its methyl ester) when pyrolysed in the presence of tetramethylammonium hydroxide. Of additional general interest is the demonstration of the advantages of acetonitrile as a solvent for extracting water-soluble compounds from tissues.     

The mechanical behaviour of some molluscan hard tissues

Pieces of shell from 19 species of molluscs exhibiting various microstructures were tested for tensile strength, modulus of elasticity in bending and modulus of rupture. In tensile strength most shells with cross-foliated, foliated, homogeneous and crossed-lamellar structures did not exceed 60 MNm ² but prismatic and nacreous structures often exceeded this value. Nacreous structure was generally superior to all others in modulus of rupture tests; that of Turbo being about equal to bone. Values of modulus of elasticity were more uniform between structures. There is a general relation between mechanical properties, microstructure and the life style of each animal. Nacreous structure, which is very strong but not widely used, apparently evolved earlier than the less strong but widely used crossed-lamellar structure.     

The distribution of taurine in the tissues of some species of insects

Taurine concentration was measured in the tissues of Schistocerca americana gregaria, Blatella orientalis and Tenebrio molitor and was found to be present in all those examined. In the locust Schistocerca gregaria it was found in particularly high concentration in active flight muscle (26 μmol/g) to a lesser extent in the eye (7 μmol/g). The thoracic concentration of taurine in developing locusts showed a strong correlation with the development of flight muscle, increasing from 4.4 to 11.3 μmol/g in the thorax during the first 24 days of adult life. Analysis of the thoracic content of taurine in adults of the three species examined confirmed that high taurine concentrations are associated with fully functional flight muscle. The concentration in the thorax of the flightless flour beetle T. molitor was only 1.79 μmol/g compared to 11.33 μmol/g for the locust. Stress due to flying and picrotoxin poisoning caused the release of taurine from the muscles into the haemolymph, causing the concentration to rise from 1.1 to 2.2 and 5.76 μmol/g respectively. Analysis of the distribution of arginine kinase showed that this release was not due to breakdown of the muscle tissue.     

Study of lipase-catalyzed hydrolysis of some monoterpene esters

Studies of the hydrolysis of bornyl, citronellyl, geranyl, and terpenyl acetates by commercially available lipases of Candida rugosa, Rhizopus arrhizus, and Mucor miehei are presented. The hydrolysis of these monoterpene esters is investigated at various temperatures and pHs, and the time dependence of the percentage of esters hydrolysed is studied. The catalytic activities of the lipases in hydrolysing the esters are compared and, overall, it is observed that under the experimental conditions used the nonspecific lipase from C. rugosa produces the highest yields of the monoterpene alcohols in comparison to the primary-ester specific lipases such as R. arrhizus and M. miehei. A rate kinetic model has been used to understand the time dependence of the yield of the product acid.     

Quantitation of muscle glycogen phosphorylase mRNA and enzyme amounts in adult rat tissues

Mammalian glycogen phosphorylases comprise a family of isozymes that are expressed selectively in a variety of cell types. As an initial step towards understanding the molecular processes that regulate the differential expression of the phosphorylase family, we have begun a quantitative examination of isozyme expression in vivo. In this paper, we report quantitative estimates of the amounts of the muscle (M) isozyme and its mRNA in adult rat tissues. Quantitative estimates of the amount of M-phosphorylase were obtained by an analysis involving electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose filters and sequential treatment with M-isozyme specific antibody and radioactively- labeled protein A. M-phosphorylase mRNA amounts were determined by an analysis involving transfer of RNA from agarose gels to nitrocellulose filters and subsequent hybridization with radioactively labelled rat M-phosphorylase cDNA. These studies indicate that M-phosphorylase is present in all tissues tested with the possible exception of liver. These are skeletal muscle, heart, brain, stomach, lung, kidney, spleen and testis. Quantitation of M-phosphorylase amounts indicate that there is a wide spectrum of variation (over 1000-fold range) in the relative amounts of the M-isozymes in these tissues. Relative mRNA levels parallel isozyme levels indicating that the major control of expression of this isozyme is governed by mRNA accumulation.